1Porting Guide 2============= 3 4Introduction 5------------ 6 7Porting Trusted Firmware-A (TF-A) to a new platform involves making some 8mandatory and optional modifications for both the cold and warm boot paths. 9Modifications consist of: 10 11- Implementing a platform-specific function or variable, 12- Setting up the execution context in a certain way, or 13- Defining certain constants (for example #defines). 14 15The platform-specific functions and variables are declared in 16``include/plat/common/platform.h``. The firmware provides a default 17implementation of variables and functions to fulfill the optional requirements 18in order to ease the porting effort. Each platform port can use them as is or 19provide their own implementation if the default implementation is inadequate. 20 21 .. note:: 22 23 TF-A historically provided default implementations of platform interfaces 24 as *weak* functions. This practice is now discouraged and new platform 25 interfaces as they get introduced in the code base should be *strongly* 26 defined. We intend to convert existing weak functions over time. Until 27 then, you will find references to *weak* functions in this document. 28 29Please review the :ref:`Threat Model` documents as part of the porting 30effort. Some platform interfaces play a key role in mitigating against some of 31the threats. Failing to fulfill these expectations could undermine the security 32guarantees offered by TF-A. These platform responsibilities are highlighted in 33the threat assessment section, under the "`Mitigations implemented?`" box for 34each threat. 35 36Some modifications are common to all Boot Loader (BL) stages. Section 2 37discusses these in detail. The subsequent sections discuss the remaining 38modifications for each BL stage in detail. 39 40Please refer to the :ref:`Platform Ports Policy` for the policy regarding 41compatibility and deprecation of these porting interfaces. 42 43Only Arm development platforms (such as FVP and Juno) may use the 44functions/definitions in ``include/plat/arm/common/`` and the corresponding 45source files in ``plat/arm/common/``. This is done so that there are no 46dependencies between platforms maintained by different people/companies. If you 47want to use any of the functionality present in ``plat/arm`` files, please 48propose a patch that moves the code to ``plat/common`` so that it can be 49discussed. 50 51Common modifications 52-------------------- 53 54This section covers the modifications that should be made by the platform for 55each BL stage to correctly port the firmware stack. They are categorized as 56either mandatory or optional. 57 58Common mandatory modifications 59------------------------------ 60 61A platform port must enable the Memory Management Unit (MMU) as well as the 62instruction and data caches for each BL stage. Setting up the translation 63tables is the responsibility of the platform port because memory maps differ 64across platforms. A memory translation library (see ``lib/xlat_tables_v2/``) is 65provided to help in this setup. 66 67Note that although this library supports non-identity mappings, this is intended 68only for re-mapping peripheral physical addresses and allows platforms with high 69I/O addresses to reduce their virtual address space. All other addresses 70corresponding to code and data must currently use an identity mapping. 71 72Also, the only translation granule size supported in TF-A is 4KB, as various 73parts of the code assume that is the case. It is not possible to switch to 7416 KB or 64 KB granule sizes at the moment. 75 76In Arm standard platforms, each BL stage configures the MMU in the 77platform-specific architecture setup function, ``blX_plat_arch_setup()``, and uses 78an identity mapping for all addresses. 79 80If the build option ``USE_COHERENT_MEM`` is enabled, each platform can allocate a 81block of identity mapped secure memory with Device-nGnRE attributes aligned to 82page boundary (4K) for each BL stage. All sections which allocate coherent 83memory are grouped under ``.coherent_ram``. For ex: Bakery locks are placed in a 84section identified by name ``.bakery_lock`` inside ``.coherent_ram`` so that its 85possible for the firmware to place variables in it using the following C code 86directive: 87 88:: 89 90 __section(".bakery_lock") 91 92Or alternatively the following assembler code directive: 93 94:: 95 96 .section .bakery_lock 97 98The ``.coherent_ram`` section is a sum of all sections like ``.bakery_lock`` which are 99used to allocate any data structures that are accessed both when a CPU is 100executing with its MMU and caches enabled, and when it's running with its MMU 101and caches disabled. Examples are given below. 102 103The following variables, functions and constants must be defined by the platform 104for the firmware to work correctly. 105 106.. _platform_def_mandatory: 107 108File : platform_def.h [mandatory] 109~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 110 111Each platform must ensure that a header file of this name is in the system 112include path with the following constants defined. This will require updating 113the list of ``PLAT_INCLUDES`` in the ``platform.mk`` file. 114 115Platform ports may optionally use the file ``include/plat/common/common_def.h``, 116which provides typical values for some of the constants below. These values are 117likely to be suitable for all platform ports. 118 119- **#define : PLATFORM_LINKER_FORMAT** 120 121 Defines the linker format used by the platform, for example 122 ``elf64-littleaarch64``. 123 124- **#define : PLATFORM_LINKER_ARCH** 125 126 Defines the processor architecture for the linker by the platform, for 127 example ``aarch64``. 128 129- **#define : PLATFORM_STACK_SIZE** 130 131 Defines the normal stack memory available to each CPU. This constant is used 132 by ``plat/common/aarch64/platform_mp_stack.S`` and 133 ``plat/common/aarch64/platform_up_stack.S``. 134 135- **#define : CACHE_WRITEBACK_GRANULE** 136 137 Defines the size in bytes of the largest cache line across all the cache 138 levels in the platform. 139 140- **#define : FIRMWARE_WELCOME_STR** 141 142 Defines the character string printed by BL1 upon entry into the ``bl1_main()`` 143 function. 144 145- **#define : PLATFORM_CORE_COUNT** 146 147 Defines the total number of CPUs implemented by the platform across all 148 clusters in the system. 149 150- **#define : PLAT_NUM_PWR_DOMAINS** 151 152 Defines the total number of nodes in the power domain topology 153 tree at all the power domain levels used by the platform. 154 This macro is used by the PSCI implementation to allocate 155 data structures to represent power domain topology. 156 157- **#define : PLAT_MAX_PWR_LVL** 158 159 Defines the maximum power domain level that the power management operations 160 should apply to. More often, but not always, the power domain level 161 corresponds to affinity level. This macro allows the PSCI implementation 162 to know the highest power domain level that it should consider for power 163 management operations in the system that the platform implements. For 164 example, the Base AEM FVP implements two clusters with a configurable 165 number of CPUs and it reports the maximum power domain level as 1. 166 167- **#define : PLAT_MAX_OFF_STATE** 168 169 Defines the local power state corresponding to the deepest power down 170 possible at every power domain level in the platform. The local power 171 states for each level may be sparsely allocated between 0 and this value 172 with 0 being reserved for the RUN state. The PSCI implementation uses this 173 value to initialize the local power states of the power domain nodes and 174 to specify the requested power state for a PSCI_CPU_OFF call. 175 176- **#define : PLAT_MAX_RET_STATE** 177 178 Defines the local power state corresponding to the deepest retention state 179 possible at every power domain level in the platform. This macro should be 180 a value less than PLAT_MAX_OFF_STATE and greater than 0. It is used by the 181 PSCI implementation to distinguish between retention and power down local 182 power states within PSCI_CPU_SUSPEND call. 183 184- **#define : PLAT_MAX_PWR_LVL_STATES** 185 186 Defines the maximum number of local power states per power domain level 187 that the platform supports. The default value of this macro is 2 since 188 most platforms just support a maximum of two local power states at each 189 power domain level (power-down and retention). If the platform needs to 190 account for more local power states, then it must redefine this macro. 191 192 Currently, this macro is used by the Generic PSCI implementation to size 193 the array used for PSCI_STAT_COUNT/RESIDENCY accounting. 194 195- **#define : BL1_RO_BASE** 196 197 Defines the base address in secure ROM where BL1 originally lives. Must be 198 aligned on a page-size boundary. 199 200- **#define : BL1_RO_LIMIT** 201 202 Defines the maximum address in secure ROM that BL1's actual content (i.e. 203 excluding any data section allocated at runtime) can occupy. 204 205- **#define : BL1_RW_BASE** 206 207 Defines the base address in secure RAM where BL1's read-write data will live 208 at runtime. Must be aligned on a page-size boundary. 209 210- **#define : BL1_RW_LIMIT** 211 212 Defines the maximum address in secure RAM that BL1's read-write data can 213 occupy at runtime. 214 215- **#define : BL2_BASE** 216 217 Defines the base address in secure RAM where BL1 loads the BL2 binary image. 218 Must be aligned on a page-size boundary. This constant is not applicable 219 when BL2_IN_XIP_MEM is set to '1'. 220 221- **#define : BL2_LIMIT** 222 223 Defines the maximum address in secure RAM that the BL2 image can occupy. 224 This constant is not applicable when BL2_IN_XIP_MEM is set to '1'. 225 226- **#define : BL2_RO_BASE** 227 228 Defines the base address in secure XIP memory where BL2 RO section originally 229 lives. Must be aligned on a page-size boundary. This constant is only needed 230 when BL2_IN_XIP_MEM is set to '1'. 231 232- **#define : BL2_RO_LIMIT** 233 234 Defines the maximum address in secure XIP memory that BL2's actual content 235 (i.e. excluding any data section allocated at runtime) can occupy. This 236 constant is only needed when BL2_IN_XIP_MEM is set to '1'. 237 238- **#define : BL2_RW_BASE** 239 240 Defines the base address in secure RAM where BL2's read-write data will live 241 at runtime. Must be aligned on a page-size boundary. This constant is only 242 needed when BL2_IN_XIP_MEM is set to '1'. 243 244- **#define : BL2_RW_LIMIT** 245 246 Defines the maximum address in secure RAM that BL2's read-write data can 247 occupy at runtime. This constant is only needed when BL2_IN_XIP_MEM is set 248 to '1'. 249 250- **#define : BL31_BASE** 251 252 Defines the base address in secure RAM where BL2 loads the BL31 binary 253 image. Must be aligned on a page-size boundary. 254 255- **#define : BL31_LIMIT** 256 257 Defines the maximum address in secure RAM that the BL31 image can occupy. 258 259- **#define : PLAT_RSE_COMMS_PAYLOAD_MAX_SIZE** 260 261 Defines the maximum message size between AP and RSE. Need to define if 262 platform supports RSE. 263 264For every image, the platform must define individual identifiers that will be 265used by BL1 or BL2 to load the corresponding image into memory from non-volatile 266storage. For the sake of performance, integer numbers will be used as 267identifiers. The platform will use those identifiers to return the relevant 268information about the image to be loaded (file handler, load address, 269authentication information, etc.). The following image identifiers are 270mandatory: 271 272- **#define : BL2_IMAGE_ID** 273 274 BL2 image identifier, used by BL1 to load BL2. 275 276- **#define : BL31_IMAGE_ID** 277 278 BL31 image identifier, used by BL2 to load BL31. 279 280- **#define : BL33_IMAGE_ID** 281 282 BL33 image identifier, used by BL2 to load BL33. 283 284If Trusted Board Boot is enabled, the following certificate identifiers must 285also be defined: 286 287- **#define : TRUSTED_BOOT_FW_CERT_ID** 288 289 BL2 content certificate identifier, used by BL1 to load the BL2 content 290 certificate. 291 292- **#define : TRUSTED_KEY_CERT_ID** 293 294 Trusted key certificate identifier, used by BL2 to load the trusted key 295 certificate. 296 297- **#define : SOC_FW_KEY_CERT_ID** 298 299 BL31 key certificate identifier, used by BL2 to load the BL31 key 300 certificate. 301 302- **#define : SOC_FW_CONTENT_CERT_ID** 303 304 BL31 content certificate identifier, used by BL2 to load the BL31 content 305 certificate. 306 307- **#define : NON_TRUSTED_FW_KEY_CERT_ID** 308 309 BL33 key certificate identifier, used by BL2 to load the BL33 key 310 certificate. 311 312- **#define : NON_TRUSTED_FW_CONTENT_CERT_ID** 313 314 BL33 content certificate identifier, used by BL2 to load the BL33 content 315 certificate. 316 317- **#define : FWU_CERT_ID** 318 319 Firmware Update (FWU) certificate identifier, used by NS_BL1U to load the 320 FWU content certificate. 321 322If the AP Firmware Updater Configuration image, BL2U is used, the following 323must also be defined: 324 325- **#define : BL2U_BASE** 326 327 Defines the base address in secure memory where BL1 copies the BL2U binary 328 image. Must be aligned on a page-size boundary. 329 330- **#define : BL2U_LIMIT** 331 332 Defines the maximum address in secure memory that the BL2U image can occupy. 333 334- **#define : BL2U_IMAGE_ID** 335 336 BL2U image identifier, used by BL1 to fetch an image descriptor 337 corresponding to BL2U. 338 339If the SCP Firmware Update Configuration Image, SCP_BL2U is used, the following 340must also be defined: 341 342- **#define : SCP_BL2U_IMAGE_ID** 343 344 SCP_BL2U image identifier, used by BL1 to fetch an image descriptor 345 corresponding to SCP_BL2U. 346 347 .. note:: 348 TF-A does not provide source code for this image. 349 350If the Non-Secure Firmware Updater ROM, NS_BL1U is used, the following must 351also be defined: 352 353- **#define : NS_BL1U_BASE** 354 355 Defines the base address in non-secure ROM where NS_BL1U executes. 356 Must be aligned on a page-size boundary. 357 358 .. note:: 359 TF-A does not provide source code for this image. 360 361- **#define : NS_BL1U_IMAGE_ID** 362 363 NS_BL1U image identifier, used by BL1 to fetch an image descriptor 364 corresponding to NS_BL1U. 365 366If the Non-Secure Firmware Updater, NS_BL2U is used, the following must also 367be defined: 368 369- **#define : NS_BL2U_BASE** 370 371 Defines the base address in non-secure memory where NS_BL2U executes. 372 Must be aligned on a page-size boundary. 373 374 .. note:: 375 TF-A does not provide source code for this image. 376 377- **#define : NS_BL2U_IMAGE_ID** 378 379 NS_BL2U image identifier, used by BL1 to fetch an image descriptor 380 corresponding to NS_BL2U. 381 382For the the Firmware update capability of TRUSTED BOARD BOOT, the following 383macros may also be defined: 384 385- **#define : PLAT_FWU_MAX_SIMULTANEOUS_IMAGES** 386 387 Total number of images that can be loaded simultaneously. If the platform 388 doesn't specify any value, it defaults to 10. 389 390If a SCP_BL2 image is supported by the platform, the following constants must 391also be defined: 392 393- **#define : SCP_BL2_IMAGE_ID** 394 395 SCP_BL2 image identifier, used by BL2 to load SCP_BL2 into secure memory 396 from platform storage before being transferred to the SCP. 397 398- **#define : SCP_FW_KEY_CERT_ID** 399 400 SCP_BL2 key certificate identifier, used by BL2 to load the SCP_BL2 key 401 certificate (mandatory when Trusted Board Boot is enabled). 402 403- **#define : SCP_FW_CONTENT_CERT_ID** 404 405 SCP_BL2 content certificate identifier, used by BL2 to load the SCP_BL2 406 content certificate (mandatory when Trusted Board Boot is enabled). 407 408If a BL32 image is supported by the platform, the following constants must 409also be defined: 410 411- **#define : BL32_IMAGE_ID** 412 413 BL32 image identifier, used by BL2 to load BL32. 414 415- **#define : TRUSTED_OS_FW_KEY_CERT_ID** 416 417 BL32 key certificate identifier, used by BL2 to load the BL32 key 418 certificate (mandatory when Trusted Board Boot is enabled). 419 420- **#define : TRUSTED_OS_FW_CONTENT_CERT_ID** 421 422 BL32 content certificate identifier, used by BL2 to load the BL32 content 423 certificate (mandatory when Trusted Board Boot is enabled). 424 425- **#define : BL32_BASE** 426 427 Defines the base address in secure memory where BL2 loads the BL32 binary 428 image. Must be aligned on a page-size boundary. 429 430- **#define : BL32_LIMIT** 431 432 Defines the maximum address that the BL32 image can occupy. 433 434If the Test Secure-EL1 Payload (TSP) instantiation of BL32 is supported by the 435platform, the following constants must also be defined: 436 437- **#define : TSP_SEC_MEM_BASE** 438 439 Defines the base address of the secure memory used by the TSP image on the 440 platform. This must be at the same address or below ``BL32_BASE``. 441 442- **#define : TSP_SEC_MEM_SIZE** 443 444 Defines the size of the secure memory used by the BL32 image on the 445 platform. ``TSP_SEC_MEM_BASE`` and ``TSP_SEC_MEM_SIZE`` must fully 446 accommodate the memory required by the BL32 image, defined by ``BL32_BASE`` 447 and ``BL32_LIMIT``. 448 449- **#define : TSP_IRQ_SEC_PHY_TIMER** 450 451 Defines the ID of the secure physical generic timer interrupt used by the 452 TSP's interrupt handling code. 453 454If the platform port uses the translation table library code, the following 455constants must also be defined: 456 457- **#define : PLAT_XLAT_TABLES_DYNAMIC** 458 459 Optional flag that can be set per-image to enable the dynamic allocation of 460 regions even when the MMU is enabled. If not defined, only static 461 functionality will be available, if defined and set to 1 it will also 462 include the dynamic functionality. 463 464- **#define : MAX_XLAT_TABLES** 465 466 Defines the maximum number of translation tables that are allocated by the 467 translation table library code. To minimize the amount of runtime memory 468 used, choose the smallest value needed to map the required virtual addresses 469 for each BL stage. If ``PLAT_XLAT_TABLES_DYNAMIC`` flag is enabled for a BL 470 image, ``MAX_XLAT_TABLES`` must be defined to accommodate the dynamic regions 471 as well. 472 473- **#define : MAX_MMAP_REGIONS** 474 475 Defines the maximum number of regions that are allocated by the translation 476 table library code. A region consists of physical base address, virtual base 477 address, size and attributes (Device/Memory, RO/RW, Secure/Non-Secure), as 478 defined in the ``mmap_region_t`` structure. The platform defines the regions 479 that should be mapped. Then, the translation table library will create the 480 corresponding tables and descriptors at runtime. To minimize the amount of 481 runtime memory used, choose the smallest value needed to register the 482 required regions for each BL stage. If ``PLAT_XLAT_TABLES_DYNAMIC`` flag is 483 enabled for a BL image, ``MAX_MMAP_REGIONS`` must be defined to accommodate 484 the dynamic regions as well. 485 486- **#define : PLAT_VIRT_ADDR_SPACE_SIZE** 487 488 Defines the total size of the virtual address space in bytes. For example, 489 for a 32 bit virtual address space, this value should be ``(1ULL << 32)``. 490 491- **#define : PLAT_PHY_ADDR_SPACE_SIZE** 492 493 Defines the total size of the physical address space in bytes. For example, 494 for a 32 bit physical address space, this value should be ``(1ULL << 32)``. 495 496If the platform port uses the IO storage framework, the following constants 497must also be defined: 498 499- **#define : MAX_IO_DEVICES** 500 501 Defines the maximum number of registered IO devices. Attempting to register 502 more devices than this value using ``io_register_device()`` will fail with 503 -ENOMEM. 504 505- **#define : MAX_IO_HANDLES** 506 507 Defines the maximum number of open IO handles. Attempting to open more IO 508 entities than this value using ``io_open()`` will fail with -ENOMEM. 509 510- **#define : MAX_IO_BLOCK_DEVICES** 511 512 Defines the maximum number of registered IO block devices. Attempting to 513 register more devices this value using ``io_dev_open()`` will fail 514 with -ENOMEM. MAX_IO_BLOCK_DEVICES should be less than MAX_IO_DEVICES. 515 With this macro, multiple block devices could be supported at the same 516 time. 517 518If the platform needs to allocate data within the per-cpu data framework in 519BL31, it should define the following macro. Currently this is only required if 520the platform decides not to use the coherent memory section by undefining the 521``USE_COHERENT_MEM`` build flag. In this case, the framework allocates the 522required memory within the the per-cpu data to minimize wastage. 523 524- **#define : PLAT_PCPU_DATA_SIZE** 525 526 Defines the memory (in bytes) to be reserved within the per-cpu data 527 structure for use by the platform layer. 528 529The following constants are optional. They should be defined when the platform 530memory layout implies some image overlaying like in Arm standard platforms. 531 532- **#define : BL31_PROGBITS_LIMIT** 533 534 Defines the maximum address in secure RAM that the BL31's progbits sections 535 can occupy. 536 537- **#define : TSP_PROGBITS_LIMIT** 538 539 Defines the maximum address that the TSP's progbits sections can occupy. 540 541If the platform supports OS-initiated mode, i.e. the build option 542``PSCI_OS_INIT_MODE`` is enabled, and if the platform's maximum power domain 543level for PSCI_CPU_SUSPEND differs from ``PLAT_MAX_PWR_LVL``, the following 544constant must be defined. 545 546- **#define : PLAT_MAX_CPU_SUSPEND_PWR_LVL** 547 548 Defines the maximum power domain level that PSCI_CPU_SUSPEND should apply to. 549 550If the platform port uses the PL061 GPIO driver, the following constant may 551optionally be defined: 552 553- **PLAT_PL061_MAX_GPIOS** 554 Maximum number of GPIOs required by the platform. This allows control how 555 much memory is allocated for PL061 GPIO controllers. The default value is 556 557 #. $(eval $(call add_define,PLAT_PL061_MAX_GPIOS)) 558 559If the platform port uses the partition driver, the following constant may 560optionally be defined: 561 562- **PLAT_PARTITION_MAX_ENTRIES** 563 Maximum number of partition entries required by the platform. This allows 564 control how much memory is allocated for partition entries. The default 565 value is 128. 566 For example, define the build flag in ``platform.mk``: 567 PLAT_PARTITION_MAX_ENTRIES := 12 568 $(eval $(call add_define,PLAT_PARTITION_MAX_ENTRIES)) 569 570- **PLAT_PARTITION_BLOCK_SIZE** 571 The size of partition block. It could be either 512 bytes or 4096 bytes. 572 The default value is 512. 573 For example, define the build flag in ``platform.mk``: 574 PLAT_PARTITION_BLOCK_SIZE := 4096 575 $(eval $(call add_define,PLAT_PARTITION_BLOCK_SIZE)) 576 577If the platform port uses the Arm® Ethos™-N NPU driver, the following 578configuration must be performed: 579 580- The NPU SiP service handler must be hooked up. This consists of both the 581 initial setup (``ethosn_smc_setup``) and the handler itself 582 (``ethosn_smc_handler``) 583 584If the platform port uses the Arm® Ethos™-N NPU driver with TZMP1 support 585enabled, the following constants and configuration must also be defined: 586 587- **ETHOSN_NPU_PROT_FW_NSAID** 588 589 Defines the Non-secure Access IDentity (NSAID) that the NPU shall use to 590 access the protected memory that contains the NPU's firmware. 591 592- **ETHOSN_NPU_PROT_DATA_RW_NSAID** 593 594 Defines the Non-secure Access IDentity (NSAID) that the NPU shall use for 595 read/write access to the protected memory that contains inference data. 596 597- **ETHOSN_NPU_PROT_DATA_RO_NSAID** 598 599 Defines the Non-secure Access IDentity (NSAID) that the NPU shall use for 600 read-only access to the protected memory that contains inference data. 601 602- **ETHOSN_NPU_NS_RW_DATA_NSAID** 603 604 Defines the Non-secure Access IDentity (NSAID) that the NPU shall use for 605 read/write access to the non-protected memory. 606 607- **ETHOSN_NPU_NS_RO_DATA_NSAID** 608 609 Defines the Non-secure Access IDentity (NSAID) that the NPU shall use for 610 read-only access to the non-protected memory. 611 612- **ETHOSN_NPU_FW_IMAGE_BASE** and **ETHOSN_NPU_FW_IMAGE_LIMIT** 613 614 Defines the physical address range that the NPU's firmware will be loaded 615 into and executed from. 616 617- Configure the platforms TrustZone Controller (TZC) with appropriate regions 618 of protected memory. At minimum this must include a region for the NPU's 619 firmware code and a region for protected inference data, and these must be 620 accessible using the NSAIDs defined above. 621 622- Include the NPU firmware and certificates in the FIP. 623 624- Provide FCONF entries to configure the image source for the NPU firmware 625 and certificates. 626 627- Add MMU mappings such that: 628 629 - BL2 can write the NPU firmware into the region defined by 630 ``ETHOSN_NPU_FW_IMAGE_BASE`` and ``ETHOSN_NPU_FW_IMAGE_LIMIT`` 631 - BL31 (SiP service) can read the NPU firmware from the same region 632 633- Add the firmware image ID ``ETHOSN_NPU_FW_IMAGE_ID`` to the list of images 634 loaded by BL2. 635 636Please see the reference implementation code for the Juno platform as an example. 637 638 639The following constant is optional. It should be defined to override the default 640behaviour of the ``assert()`` function (for example, to save memory). 641 642- **PLAT_LOG_LEVEL_ASSERT** 643 If ``PLAT_LOG_LEVEL_ASSERT`` is higher or equal than ``LOG_LEVEL_VERBOSE``, 644 ``assert()`` prints the name of the file, the line number and the asserted 645 expression. Else if it is higher than ``LOG_LEVEL_INFO``, it prints the file 646 name and the line number. Else if it is lower than ``LOG_LEVEL_INFO``, it 647 doesn't print anything to the console. If ``PLAT_LOG_LEVEL_ASSERT`` isn't 648 defined, it defaults to ``LOG_LEVEL``. 649 650If the platform port uses the DRTM feature, the following constants must be 651defined: 652 653- **#define : PLAT_DRTM_EVENT_LOG_MAX_SIZE** 654 655 Maximum Event Log size used by the platform. Platform can decide the maximum 656 size of the Event Log buffer, depending upon the highest hash algorithm 657 chosen and the number of components selected to measure during the DRTM 658 execution flow. 659 660- **#define : PLAT_DRTM_MMAP_ENTRIES** 661 662 Number of the MMAP entries used by the DRTM implementation to calculate the 663 size of address map region of the platform. 664 665File : plat_macros.S [mandatory] 666~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 667 668Each platform must ensure a file of this name is in the system include path with 669the following macro defined. In the Arm development platforms, this file is 670found in ``plat/arm/board/<plat_name>/include/plat_macros.S``. 671 672- **Macro : plat_crash_print_regs** 673 674 This macro allows the crash reporting routine to print relevant platform 675 registers in case of an unhandled exception in BL31. This aids in debugging 676 and this macro can be defined to be empty in case register reporting is not 677 desired. 678 679 For instance, GIC or interconnect registers may be helpful for 680 troubleshooting. 681 682Handling Reset 683-------------- 684 685BL1 by default implements the reset vector where execution starts from a cold 686or warm boot. BL31 can be optionally set as a reset vector using the 687``RESET_TO_BL31`` make variable. 688 689For each CPU, the reset vector code is responsible for the following tasks: 690 691#. Distinguishing between a cold boot and a warm boot. 692 693#. In the case of a cold boot and the CPU being a secondary CPU, ensuring that 694 the CPU is placed in a platform-specific state until the primary CPU 695 performs the necessary steps to remove it from this state. 696 697#. In the case of a warm boot, ensuring that the CPU jumps to a platform- 698 specific address in the BL31 image in the same processor mode as it was 699 when released from reset. 700 701The following functions need to be implemented by the platform port to enable 702reset vector code to perform the above tasks. 703 704Function : plat_get_my_entrypoint() [mandatory when PROGRAMMABLE_RESET_ADDRESS == 0] 705~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 706 707:: 708 709 Argument : void 710 Return : uintptr_t 711 712This function is called with the MMU and caches disabled 713(``SCTLR_EL3.M`` = 0 and ``SCTLR_EL3.C`` = 0). The function is responsible for 714distinguishing between a warm and cold reset for the current CPU using 715platform-specific means. If it's a warm reset, then it returns the warm 716reset entrypoint point provided to ``plat_setup_psci_ops()`` during 717BL31 initialization. If it's a cold reset then this function must return zero. 718 719This function does not follow the Procedure Call Standard used by the 720Application Binary Interface for the Arm 64-bit architecture. The caller should 721not assume that callee saved registers are preserved across a call to this 722function. 723 724This function fulfills requirement 1 and 3 listed above. 725 726Note that for platforms that support programming the reset address, it is 727expected that a CPU will start executing code directly at the right address, 728both on a cold and warm reset. In this case, there is no need to identify the 729type of reset nor to query the warm reset entrypoint. Therefore, implementing 730this function is not required on such platforms. 731 732Function : plat_secondary_cold_boot_setup() [mandatory when COLD_BOOT_SINGLE_CPU == 0] 733~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 734 735:: 736 737 Argument : void 738 739This function is called with the MMU and data caches disabled. It is responsible 740for placing the executing secondary CPU in a platform-specific state until the 741primary CPU performs the necessary actions to bring it out of that state and 742allow entry into the OS. This function must not return. 743 744In the Arm FVP port, when using the normal boot flow, each secondary CPU powers 745itself off. The primary CPU is responsible for powering up the secondary CPUs 746when normal world software requires them. When booting an EL3 payload instead, 747they stay powered on and are put in a holding pen until their mailbox gets 748populated. 749 750This function fulfills requirement 2 above. 751 752Note that for platforms that can't release secondary CPUs out of reset, only the 753primary CPU will execute the cold boot code. Therefore, implementing this 754function is not required on such platforms. 755 756Function : plat_is_my_cpu_primary() [mandatory when COLD_BOOT_SINGLE_CPU == 0] 757~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 758 759:: 760 761 Argument : void 762 Return : unsigned int 763 764This function identifies whether the current CPU is the primary CPU or a 765secondary CPU. A return value of zero indicates that the CPU is not the 766primary CPU, while a non-zero return value indicates that the CPU is the 767primary CPU. 768 769Note that for platforms that can't release secondary CPUs out of reset, only the 770primary CPU will execute the cold boot code. Therefore, there is no need to 771distinguish between primary and secondary CPUs and implementing this function is 772not required. 773 774Function : platform_mem_init() [mandatory] 775~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 776 777:: 778 779 Argument : void 780 Return : void 781 782This function is called before any access to data is made by the firmware, in 783order to carry out any essential memory initialization. 784 785Function: plat_get_rotpk_info() 786~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 787 788:: 789 790 Argument : void *, void **, unsigned int *, unsigned int * 791 Return : int 792 793This function is mandatory when Trusted Board Boot is enabled. It returns a 794pointer to the ROTPK stored in the platform (or a hash of it) and its length. 795The ROTPK must be encoded in DER format according to the following ASN.1 796structure: 797 798:: 799 800 AlgorithmIdentifier ::= SEQUENCE { 801 algorithm OBJECT IDENTIFIER, 802 parameters ANY DEFINED BY algorithm OPTIONAL 803 } 804 805 SubjectPublicKeyInfo ::= SEQUENCE { 806 algorithm AlgorithmIdentifier, 807 subjectPublicKey BIT STRING 808 } 809 810In case the function returns a hash of the key: 811 812:: 813 814 DigestInfo ::= SEQUENCE { 815 digestAlgorithm AlgorithmIdentifier, 816 digest OCTET STRING 817 } 818 819The function returns 0 on success. Any other value is treated as error by the 820Trusted Board Boot. The function also reports extra information related 821to the ROTPK in the flags parameter: 822 823:: 824 825 ROTPK_IS_HASH : Indicates that the ROTPK returned by the platform is a 826 hash. 827 ROTPK_NOT_DEPLOYED : This allows the platform to skip certificate ROTPK 828 verification while the platform ROTPK is not deployed. 829 When this flag is set, the function does not need to 830 return a platform ROTPK, and the authentication 831 framework uses the ROTPK in the certificate without 832 verifying it against the platform value. This flag 833 must not be used in a deployed production environment. 834 835Function: plat_get_nv_ctr() 836~~~~~~~~~~~~~~~~~~~~~~~~~~~ 837 838:: 839 840 Argument : void *, unsigned int * 841 Return : int 842 843This function is mandatory when Trusted Board Boot is enabled. It returns the 844non-volatile counter value stored in the platform in the second argument. The 845cookie in the first argument may be used to select the counter in case the 846platform provides more than one (for example, on platforms that use the default 847TBBR CoT, the cookie will correspond to the OID values defined in 848TRUSTED_FW_NVCOUNTER_OID or NON_TRUSTED_FW_NVCOUNTER_OID). 849 850The function returns 0 on success. Any other value means the counter value could 851not be retrieved from the platform. 852 853Function: plat_set_nv_ctr() 854~~~~~~~~~~~~~~~~~~~~~~~~~~~ 855 856:: 857 858 Argument : void *, unsigned int 859 Return : int 860 861This function is mandatory when Trusted Board Boot is enabled. It sets a new 862counter value in the platform. The cookie in the first argument may be used to 863select the counter (as explained in plat_get_nv_ctr()). The second argument is 864the updated counter value to be written to the NV counter. 865 866The function returns 0 on success. Any other value means the counter value could 867not be updated. 868 869Function: plat_set_nv_ctr2() 870~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 871 872:: 873 874 Argument : void *, const auth_img_desc_t *, unsigned int 875 Return : int 876 877This function is optional when Trusted Board Boot is enabled. If this 878interface is defined, then ``plat_set_nv_ctr()`` need not be defined. The 879first argument passed is a cookie and is typically used to 880differentiate between a Non Trusted NV Counter and a Trusted NV 881Counter. The second argument is a pointer to an authentication image 882descriptor and may be used to decide if the counter is allowed to be 883updated or not. The third argument is the updated counter value to 884be written to the NV counter. 885 886The function returns 0 on success. Any other value means the counter value 887either could not be updated or the authentication image descriptor indicates 888that it is not allowed to be updated. 889 890Dynamic Root of Trust for Measurement support (in BL31) 891------------------------------------------------------- 892 893The functions mentioned in this section are mandatory, when platform enables 894DRTM_SUPPORT build flag. 895 896Function : plat_get_addr_mmap() 897~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 898 899:: 900 901 Argument : void 902 Return : const mmap_region_t * 903 904This function is used to return the address of the platform *address-map* table, 905which describes the regions of normal memory, memory mapped I/O 906and non-volatile memory. 907 908Function : plat_has_non_host_platforms() 909~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 910 911:: 912 913 Argument : void 914 Return : bool 915 916This function returns *true* if the platform has any trusted devices capable of 917DMA, otherwise returns *false*. 918 919Function : plat_has_unmanaged_dma_peripherals() 920~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 921 922:: 923 924 Argument : void 925 Return : bool 926 927This function returns *true* if platform uses peripherals whose DMA is not 928managed by an SMMU, otherwise returns *false*. 929 930Note - 931If the platform has peripherals that are not managed by the SMMU, then the 932platform should investigate such peripherals to determine whether they can 933be trusted, and such peripherals should be moved under "Non-host platforms" 934if they can be trusted. 935 936Function : plat_get_total_num_smmus() 937~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 938 939:: 940 941 Argument : void 942 Return : unsigned int 943 944This function returns the total number of SMMUs in the platform. 945 946Function : plat_enumerate_smmus() 947~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 948:: 949 950 951 Argument : void 952 Return : const uintptr_t *, size_t 953 954This function returns an array of SMMU addresses and the actual number of SMMUs 955reported by the platform. 956 957Function : plat_drtm_get_dma_prot_features() 958~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 959 960:: 961 962 Argument : void 963 Return : const plat_drtm_dma_prot_features_t* 964 965This function returns the address of plat_drtm_dma_prot_features_t structure 966containing the maximum number of protected regions and bitmap with the types 967of DMA protection supported by the platform. 968For more details see section 3.3 Table 6 of `DRTM`_ specification. 969 970Function : plat_drtm_dma_prot_get_max_table_bytes() 971~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 972 973:: 974 975 Argument : void 976 Return : uint64_t 977 978This function returns the maximum size of DMA protected regions table in 979bytes. 980 981Function : plat_drtm_get_tpm_features() 982~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 983 984:: 985 986 Argument : void 987 Return : const plat_drtm_tpm_features_t* 988 989This function returns the address of *plat_drtm_tpm_features_t* structure 990containing PCR usage schema, TPM-based hash, and firmware hash algorithm 991supported by the platform. 992 993Function : plat_drtm_get_min_size_normal_world_dce() 994~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 995 996:: 997 998 Argument : void 999 Return : uint64_t 1000 1001This function returns the size normal-world DCE of the platform. 1002 1003Function : plat_drtm_get_imp_def_dlme_region_size() 1004~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1005 1006:: 1007 1008 Argument : void 1009 Return : uint64_t 1010 1011This function returns the size of implementation defined DLME region 1012of the platform. 1013 1014Function : plat_drtm_get_tcb_hash_table_size() 1015~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1016 1017:: 1018 1019 Argument : void 1020 Return : uint64_t 1021 1022This function returns the size of TCB hash table of the platform. 1023 1024Function : plat_drtm_get_tcb_hash_features() 1025~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1026 1027:: 1028 1029 Argument : void 1030 Return : uint64_t 1031 1032This function returns the Maximum number of TCB hashes recorded by the 1033platform. 1034For more details see section 3.3 Table 6 of `DRTM`_ specification. 1035 1036Function : plat_drtm_validate_ns_region() 1037~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1038 1039:: 1040 1041 Argument : uintptr_t, uintptr_t 1042 Return : int 1043 1044This function validates that given region is within the Non-Secure region 1045of DRAM. This function takes a region start address and size an input 1046arguments, and returns 0 on success and -1 on failure. 1047 1048Function : plat_set_drtm_error() 1049~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1050 1051:: 1052 1053 Argument : uint64_t 1054 Return : int 1055 1056This function writes a 64 bit error code received as input into 1057non-volatile storage and returns 0 on success and -1 on failure. 1058 1059Function : plat_get_drtm_error() 1060~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1061 1062:: 1063 1064 Argument : uint64_t* 1065 Return : int 1066 1067This function reads a 64 bit error code from the non-volatile storage 1068into the received address, and returns 0 on success and -1 on failure. 1069 1070Common mandatory function modifications 1071--------------------------------------- 1072 1073The following functions are mandatory functions which need to be implemented 1074by the platform port. 1075 1076Function : plat_my_core_pos() 1077~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1078 1079:: 1080 1081 Argument : void 1082 Return : unsigned int 1083 1084This function returns the index of the calling CPU which is used as a 1085CPU-specific linear index into blocks of memory (for example while allocating 1086per-CPU stacks). This function will be invoked very early in the 1087initialization sequence which mandates that this function should be 1088implemented in assembly and should not rely on the availability of a C 1089runtime environment. This function can clobber x0 - x8 and must preserve 1090x9 - x29. 1091 1092This function plays a crucial role in the power domain topology framework in 1093PSCI and details of this can be found in 1094:ref:`PSCI Power Domain Tree Structure`. 1095 1096Function : plat_core_pos_by_mpidr() 1097~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1098 1099:: 1100 1101 Argument : u_register_t 1102 Return : int 1103 1104This function validates the ``MPIDR`` of a CPU and converts it to an index, 1105which can be used as a CPU-specific linear index into blocks of memory. In 1106case the ``MPIDR`` is invalid, this function returns -1. This function will only 1107be invoked by BL31 after the power domain topology is initialized and can 1108utilize the C runtime environment. For further details about how TF-A 1109represents the power domain topology and how this relates to the linear CPU 1110index, please refer :ref:`PSCI Power Domain Tree Structure`. 1111 1112Function : plat_get_mbedtls_heap() [when TRUSTED_BOARD_BOOT == 1] 1113~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1114 1115:: 1116 1117 Arguments : void **heap_addr, size_t *heap_size 1118 Return : int 1119 1120This function is invoked during Mbed TLS library initialisation to get a heap, 1121by means of a starting address and a size. This heap will then be used 1122internally by the Mbed TLS library. Hence, each BL stage that utilises Mbed TLS 1123must be able to provide a heap to it. 1124 1125A helper function can be found in `drivers/auth/mbedtls/mbedtls_common.c` in 1126which a heap is statically reserved during compile time inside every image 1127(i.e. every BL stage) that utilises Mbed TLS. In this default implementation, 1128the function simply returns the address and size of this "pre-allocated" heap. 1129For a platform to use this default implementation, only a call to the helper 1130from inside plat_get_mbedtls_heap() body is enough and nothing else is needed. 1131 1132However, by writting their own implementation, platforms have the potential to 1133optimise memory usage. For example, on some Arm platforms, the Mbed TLS heap is 1134shared between BL1 and BL2 stages and, thus, the necessary space is not reserved 1135twice. 1136 1137On success the function should return 0 and a negative error code otherwise. 1138 1139Function : plat_get_enc_key_info() [when FW_ENC_STATUS == 0 or 1] 1140~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1141 1142:: 1143 1144 Arguments : enum fw_enc_status_t fw_enc_status, uint8_t *key, 1145 size_t *key_len, unsigned int *flags, const uint8_t *img_id, 1146 size_t img_id_len 1147 Return : int 1148 1149This function provides a symmetric key (either SSK or BSSK depending on 1150fw_enc_status) which is invoked during runtime decryption of encrypted 1151firmware images. `plat/common/plat_bl_common.c` provides a dummy weak 1152implementation for testing purposes which must be overridden by the platform 1153trying to implement a real world firmware encryption use-case. 1154 1155It also allows the platform to pass symmetric key identifier rather than 1156actual symmetric key which is useful in cases where the crypto backend provides 1157secure storage for the symmetric key. So in this case ``ENC_KEY_IS_IDENTIFIER`` 1158flag must be set in ``flags``. 1159 1160In addition to above a platform may also choose to provide an image specific 1161symmetric key/identifier using img_id. 1162 1163On success the function should return 0 and a negative error code otherwise. 1164 1165Note that this API depends on ``DECRYPTION_SUPPORT`` build flag. 1166 1167Function : plat_fwu_set_images_source() [when PSA_FWU_SUPPORT == 1] 1168~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1169 1170:: 1171 1172 Argument : const struct fwu_metadata *metadata 1173 Return : void 1174 1175This function is mandatory when PSA_FWU_SUPPORT is enabled. 1176It provides a means to retrieve image specification (offset in 1177non-volatile storage and length) of active/updated images using the passed 1178FWU metadata, and update I/O policies of active/updated images using retrieved 1179image specification information. 1180Further I/O layer operations such as I/O open, I/O read, etc. on these 1181images rely on this function call. 1182 1183In Arm platforms, this function is used to set an I/O policy of the FIP image, 1184container of all active/updated secure and non-secure images. 1185 1186Function : plat_fwu_set_metadata_image_source() [when PSA_FWU_SUPPORT == 1] 1187~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1188 1189:: 1190 1191 Argument : unsigned int image_id, uintptr_t *dev_handle, 1192 uintptr_t *image_spec 1193 Return : int 1194 1195This function is mandatory when PSA_FWU_SUPPORT is enabled. It is 1196responsible for setting up the platform I/O policy of the requested metadata 1197image (either FWU_METADATA_IMAGE_ID or BKUP_FWU_METADATA_IMAGE_ID) that will 1198be used to load this image from the platform's non-volatile storage. 1199 1200FWU metadata can not be always stored as a raw image in non-volatile storage 1201to define its image specification (offset in non-volatile storage and length) 1202statically in I/O policy. 1203For example, the FWU metadata image is stored as a partition inside the GUID 1204partition table image. Its specification is defined in the partition table 1205that needs to be parsed dynamically. 1206This function provides a means to retrieve such dynamic information to set 1207the I/O policy of the FWU metadata image. 1208Further I/O layer operations such as I/O open, I/O read, etc. on FWU metadata 1209image relies on this function call. 1210 1211It returns '0' on success, otherwise a negative error value on error. 1212Alongside, returns device handle and image specification from the I/O policy 1213of the requested FWU metadata image. 1214 1215Function : plat_fwu_get_boot_idx() [when PSA_FWU_SUPPORT == 1] 1216~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1217 1218:: 1219 1220 Argument : void 1221 Return : uint32_t 1222 1223This function is mandatory when PSA_FWU_SUPPORT is enabled. It provides the 1224means to retrieve the boot index value from the platform. The boot index is the 1225bank from which the platform has booted the firmware images. 1226 1227By default, the platform will read the metadata structure and try to boot from 1228the active bank. If the platform fails to boot from the active bank due to 1229reasons like an Authentication failure, or on crossing a set number of watchdog 1230resets while booting from the active bank, the platform can then switch to boot 1231from a different bank. This function then returns the bank that the platform 1232should boot its images from. 1233 1234Common optional modifications 1235----------------------------- 1236 1237The following are helper functions implemented by the firmware that perform 1238common platform-specific tasks. A platform may choose to override these 1239definitions. 1240 1241Function : plat_set_my_stack() 1242~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1243 1244:: 1245 1246 Argument : void 1247 Return : void 1248 1249This function sets the current stack pointer to the normal memory stack that 1250has been allocated for the current CPU. For BL images that only require a 1251stack for the primary CPU, the UP version of the function is used. The size 1252of the stack allocated to each CPU is specified by the platform defined 1253constant ``PLATFORM_STACK_SIZE``. 1254 1255Common implementations of this function for the UP and MP BL images are 1256provided in ``plat/common/aarch64/platform_up_stack.S`` and 1257``plat/common/aarch64/platform_mp_stack.S`` 1258 1259Function : plat_get_my_stack() 1260~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1261 1262:: 1263 1264 Argument : void 1265 Return : uintptr_t 1266 1267This function returns the base address of the normal memory stack that 1268has been allocated for the current CPU. For BL images that only require a 1269stack for the primary CPU, the UP version of the function is used. The size 1270of the stack allocated to each CPU is specified by the platform defined 1271constant ``PLATFORM_STACK_SIZE``. 1272 1273Common implementations of this function for the UP and MP BL images are 1274provided in ``plat/common/aarch64/platform_up_stack.S`` and 1275``plat/common/aarch64/platform_mp_stack.S`` 1276 1277Function : plat_report_exception() 1278~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1279 1280:: 1281 1282 Argument : unsigned int 1283 Return : void 1284 1285A platform may need to report various information about its status when an 1286exception is taken, for example the current exception level, the CPU security 1287state (secure/non-secure), the exception type, and so on. This function is 1288called in the following circumstances: 1289 1290- In BL1, whenever an exception is taken. 1291- In BL2, whenever an exception is taken. 1292 1293The default implementation doesn't do anything, to avoid making assumptions 1294about the way the platform displays its status information. 1295 1296For AArch64, this function receives the exception type as its argument. 1297Possible values for exceptions types are listed in the 1298``include/common/bl_common.h`` header file. Note that these constants are not 1299related to any architectural exception code; they are just a TF-A convention. 1300 1301For AArch32, this function receives the exception mode as its argument. 1302Possible values for exception modes are listed in the 1303``include/lib/aarch32/arch.h`` header file. 1304 1305Function : plat_reset_handler() 1306~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1307 1308:: 1309 1310 Argument : void 1311 Return : void 1312 1313A platform may need to do additional initialization after reset. This function 1314allows the platform to do the platform specific initializations. Platform 1315specific errata workarounds could also be implemented here. The API should 1316preserve the values of callee saved registers x19 to x29. 1317 1318The default implementation doesn't do anything. If a platform needs to override 1319the default implementation, refer to the :ref:`Firmware Design` for general 1320guidelines. 1321 1322Function : plat_disable_acp() 1323~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1324 1325:: 1326 1327 Argument : void 1328 Return : void 1329 1330This API allows a platform to disable the Accelerator Coherency Port (if 1331present) during a cluster power down sequence. The default weak implementation 1332doesn't do anything. Since this API is called during the power down sequence, 1333it has restrictions for stack usage and it can use the registers x0 - x17 as 1334scratch registers. It should preserve the value in x18 register as it is used 1335by the caller to store the return address. 1336 1337Function : plat_error_handler() 1338~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1339 1340:: 1341 1342 Argument : int 1343 Return : void 1344 1345This API is called when the generic code encounters an error situation from 1346which it cannot continue. It allows the platform to perform error reporting or 1347recovery actions (for example, reset the system). This function must not return. 1348 1349The parameter indicates the type of error using standard codes from ``errno.h``. 1350Possible errors reported by the generic code are: 1351 1352- ``-EAUTH``: a certificate or image could not be authenticated (when Trusted 1353 Board Boot is enabled) 1354- ``-ENOENT``: the requested image or certificate could not be found or an IO 1355 error was detected 1356- ``-ENOMEM``: resources exhausted. TF-A does not use dynamic memory, so this 1357 error is usually an indication of an incorrect array size 1358 1359The default implementation simply spins. 1360 1361Function : plat_panic_handler() 1362~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1363 1364:: 1365 1366 Argument : void 1367 Return : void 1368 1369This API is called when the generic code encounters an unexpected error 1370situation from which it cannot recover. This function must not return, 1371and must be implemented in assembly because it may be called before the C 1372environment is initialized. 1373 1374.. note:: 1375 The address from where it was called is stored in x30 (Link Register). 1376 The default implementation simply spins. 1377 1378Function : plat_system_reset() 1379~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1380 1381:: 1382 1383 Argument : void 1384 Return : void 1385 1386This function is used by the platform to resets the system. It can be used 1387in any specific use-case where system needs to be resetted. For example, 1388in case of DRTM implementation this function reset the system after 1389writing the DRTM error code in the non-volatile storage. This function 1390never returns. Failure in reset results in panic. 1391 1392Function : plat_get_bl_image_load_info() 1393~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1394 1395:: 1396 1397 Argument : void 1398 Return : bl_load_info_t * 1399 1400This function returns pointer to the list of images that the platform has 1401populated to load. This function is invoked in BL2 to load the 1402BL3xx images. 1403 1404Function : plat_get_next_bl_params() 1405~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1406 1407:: 1408 1409 Argument : void 1410 Return : bl_params_t * 1411 1412This function returns a pointer to the shared memory that the platform has 1413kept aside to pass TF-A related information that next BL image needs. This 1414function is invoked in BL2 to pass this information to the next BL 1415image. 1416 1417Function : plat_get_stack_protector_canary() 1418~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1419 1420:: 1421 1422 Argument : void 1423 Return : u_register_t 1424 1425This function returns a random value that is used to initialize the canary used 1426when the stack protector is enabled with ENABLE_STACK_PROTECTOR. A predictable 1427value will weaken the protection as the attacker could easily write the right 1428value as part of the attack most of the time. Therefore, it should return a 1429true random number. 1430 1431.. warning:: 1432 For the protection to be effective, the global data need to be placed at 1433 a lower address than the stack bases. Failure to do so would allow an 1434 attacker to overwrite the canary as part of the stack buffer overflow attack. 1435 1436Function : plat_flush_next_bl_params() 1437~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1438 1439:: 1440 1441 Argument : void 1442 Return : void 1443 1444This function flushes to main memory all the image params that are passed to 1445next image. This function is invoked in BL2 to flush this information 1446to the next BL image. 1447 1448Function : plat_log_get_prefix() 1449~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1450 1451:: 1452 1453 Argument : unsigned int 1454 Return : const char * 1455 1456This function defines the prefix string corresponding to the `log_level` to be 1457prepended to all the log output from TF-A. The `log_level` (argument) will 1458correspond to one of the standard log levels defined in debug.h. The platform 1459can override the common implementation to define a different prefix string for 1460the log output. The implementation should be robust to future changes that 1461increase the number of log levels. 1462 1463Function : plat_get_soc_version() 1464~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1465 1466:: 1467 1468 Argument : void 1469 Return : int32_t 1470 1471This function returns soc version which mainly consist of below fields 1472 1473:: 1474 1475 soc_version[30:24] = JEP-106 continuation code for the SiP 1476 soc_version[23:16] = JEP-106 identification code with parity bit for the SiP 1477 soc_version[15:0] = Implementation defined SoC ID 1478 1479Function : plat_get_soc_revision() 1480~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1481 1482:: 1483 1484 Argument : void 1485 Return : int32_t 1486 1487This function returns soc revision in below format 1488 1489:: 1490 1491 soc_revision[0:30] = SOC revision of specific SOC 1492 1493Function : plat_is_smccc_feature_available() 1494~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1495 1496:: 1497 1498 Argument : u_register_t 1499 Return : int32_t 1500 1501This function returns SMC_ARCH_CALL_SUCCESS if the platform supports 1502the SMCCC function specified in the argument; otherwise returns 1503SMC_ARCH_CALL_NOT_SUPPORTED. 1504 1505Function : plat_can_cmo() 1506~~~~~~~~~~~~~~~~~~~~~~~~~ 1507 1508:: 1509 1510 Argument : void 1511 Return : uint64_t 1512 1513When CONDITIONAL_CMO flag is enabled: 1514 1515- This function indicates whether cache management operations should be 1516 performed. It returns 0 if CMOs should be skipped and non-zero 1517 otherwise. 1518- The function must not clobber x1, x2 and x3. It's also not safe to rely on 1519 stack. Otherwise obey AAPCS. 1520 1521Struct: plat_try_images_ops [optional] 1522~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1523 1524This optional structure holds platform hooks for alternative images load. 1525It has to be defined in platform code and registered by calling 1526plat_setup_try_img_ops() function, passing it the address of the 1527plat_try_images_ops struct. 1528 1529Function : plat_setup_try_img_ops [optional] 1530............................................ 1531 1532:: 1533 1534 Argument : const struct plat_try_images_ops * 1535 Return : void 1536 1537This optional function is called to register platform try images ops, given 1538as argument. 1539 1540Function : plat_try_images_ops.next_instance [optional] 1541....................................................... 1542 1543:: 1544 1545 Argument : unsigned int image_id 1546 Return : int 1547 1548This optional function tries to load images from alternative places. 1549In case PSA FWU is not used, it can be any instance or media. If PSA FWU is 1550used, it is mandatory that the backup image is on the same media. 1551This is required for MTD devices like NAND. 1552The argument is the ID of the image for which we are looking for an alternative 1553place. It returns 0 in case of success and a negative errno value otherwise. 1554 1555Modifications specific to a Boot Loader stage 1556--------------------------------------------- 1557 1558Boot Loader Stage 1 (BL1) 1559------------------------- 1560 1561BL1 implements the reset vector where execution starts from after a cold or 1562warm boot. For each CPU, BL1 is responsible for the following tasks: 1563 1564#. Handling the reset as described in section 2.2 1565 1566#. In the case of a cold boot and the CPU being the primary CPU, ensuring that 1567 only this CPU executes the remaining BL1 code, including loading and passing 1568 control to the BL2 stage. 1569 1570#. Identifying and starting the Firmware Update process (if required). 1571 1572#. Loading the BL2 image from non-volatile storage into secure memory at the 1573 address specified by the platform defined constant ``BL2_BASE``. 1574 1575#. Populating a ``meminfo`` structure with the following information in memory, 1576 accessible by BL2 immediately upon entry. 1577 1578 :: 1579 1580 meminfo.total_base = Base address of secure RAM visible to BL2 1581 meminfo.total_size = Size of secure RAM visible to BL2 1582 1583 By default, BL1 places this ``meminfo`` structure at the end of secure 1584 memory visible to BL2. 1585 1586 It is possible for the platform to decide where it wants to place the 1587 ``meminfo`` structure for BL2 or restrict the amount of memory visible to 1588 BL2 by overriding the weak default implementation of 1589 ``bl1_plat_handle_post_image_load`` API. 1590 1591The following functions need to be implemented by the platform port to enable 1592BL1 to perform the above tasks. 1593 1594Function : bl1_early_platform_setup() [mandatory] 1595~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1596 1597:: 1598 1599 Argument : void 1600 Return : void 1601 1602This function executes with the MMU and data caches disabled. It is only called 1603by the primary CPU. 1604 1605On Arm standard platforms, this function: 1606 1607- Enables a secure instance of SP805 to act as the Trusted Watchdog. 1608 1609- Initializes a UART (PL011 console), which enables access to the ``printf`` 1610 family of functions in BL1. 1611 1612- Enables issuing of snoop and DVM (Distributed Virtual Memory) requests to 1613 the CCI slave interface corresponding to the cluster that includes the 1614 primary CPU. 1615 1616Function : bl1_plat_arch_setup() [mandatory] 1617~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1618 1619:: 1620 1621 Argument : void 1622 Return : void 1623 1624This function performs any platform-specific and architectural setup that the 1625platform requires. Platform-specific setup might include configuration of 1626memory controllers and the interconnect. 1627 1628In Arm standard platforms, this function enables the MMU. 1629 1630This function helps fulfill requirement 2 above. 1631 1632Function : bl1_platform_setup() [mandatory] 1633~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1634 1635:: 1636 1637 Argument : void 1638 Return : void 1639 1640This function executes with the MMU and data caches enabled. It is responsible 1641for performing any remaining platform-specific setup that can occur after the 1642MMU and data cache have been enabled. 1643 1644In Arm standard platforms, this function initializes the storage abstraction 1645layer used to load the next bootloader image. 1646 1647This function helps fulfill requirement 4 above. 1648 1649Function : bl1_plat_sec_mem_layout() [mandatory] 1650~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1651 1652:: 1653 1654 Argument : void 1655 Return : meminfo * 1656 1657This function should only be called on the cold boot path. It executes with the 1658MMU and data caches enabled. The pointer returned by this function must point to 1659a ``meminfo`` structure containing the extents and availability of secure RAM for 1660the BL1 stage. 1661 1662:: 1663 1664 meminfo.total_base = Base address of secure RAM visible to BL1 1665 meminfo.total_size = Size of secure RAM visible to BL1 1666 1667This information is used by BL1 to load the BL2 image in secure RAM. BL1 also 1668populates a similar structure to tell BL2 the extents of memory available for 1669its own use. 1670 1671This function helps fulfill requirements 4 and 5 above. 1672 1673Function : bl1_plat_prepare_exit() [optional] 1674~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1675 1676:: 1677 1678 Argument : entry_point_info_t * 1679 Return : void 1680 1681This function is called prior to exiting BL1 in response to the 1682``BL1_SMC_RUN_IMAGE`` SMC request raised by BL2. It should be used to perform 1683platform specific clean up or bookkeeping operations before transferring 1684control to the next image. It receives the address of the ``entry_point_info_t`` 1685structure passed from BL2. This function runs with MMU disabled. 1686 1687Function : bl1_plat_set_ep_info() [optional] 1688~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1689 1690:: 1691 1692 Argument : unsigned int image_id, entry_point_info_t *ep_info 1693 Return : void 1694 1695This function allows platforms to override ``ep_info`` for the given ``image_id``. 1696 1697The default implementation just returns. 1698 1699Function : bl1_plat_get_next_image_id() [optional] 1700~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1701 1702:: 1703 1704 Argument : void 1705 Return : unsigned int 1706 1707This and the following function must be overridden to enable the FWU feature. 1708 1709BL1 calls this function after platform setup to identify the next image to be 1710loaded and executed. If the platform returns ``BL2_IMAGE_ID`` then BL1 proceeds 1711with the normal boot sequence, which loads and executes BL2. If the platform 1712returns a different image id, BL1 assumes that Firmware Update is required. 1713 1714The default implementation always returns ``BL2_IMAGE_ID``. The Arm development 1715platforms override this function to detect if firmware update is required, and 1716if so, return the first image in the firmware update process. 1717 1718Function : bl1_plat_get_image_desc() [optional] 1719~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1720 1721:: 1722 1723 Argument : unsigned int image_id 1724 Return : image_desc_t * 1725 1726BL1 calls this function to get the image descriptor information ``image_desc_t`` 1727for the provided ``image_id`` from the platform. 1728 1729The default implementation always returns a common BL2 image descriptor. Arm 1730standard platforms return an image descriptor corresponding to BL2 or one of 1731the firmware update images defined in the Trusted Board Boot Requirements 1732specification. 1733 1734Function : bl1_plat_handle_pre_image_load() [optional] 1735~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1736 1737:: 1738 1739 Argument : unsigned int image_id 1740 Return : int 1741 1742This function can be used by the platforms to update/use image information 1743corresponding to ``image_id``. This function is invoked in BL1, both in cold 1744boot and FWU code path, before loading the image. 1745 1746Function : bl1_plat_calc_bl2_layout() [optional] 1747~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1748 1749:: 1750 1751 Argument : const meminfo_t *bl1_mem_layout, meminfo_t *bl2_mem_layout 1752 Return : void 1753 1754This utility function calculates the memory layout of BL2, representing it in a 1755`meminfo_t` structure. The default implementation derives this layout from the 1756positioning of BL1’s RW data at the top of the memory layout. 1757 1758Function : bl1_plat_handle_post_image_load() [optional] 1759~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1760 1761:: 1762 1763 Argument : unsigned int image_id 1764 Return : int 1765 1766This function can be used by the platforms to update/use image information 1767corresponding to ``image_id``. This function is invoked in BL1, both in cold 1768boot and FWU code path, after loading and authenticating the image. 1769 1770The default weak implementation of this function calculates the amount of 1771Trusted SRAM that can be used by BL2 and allocates a ``meminfo_t`` 1772structure at the beginning of this free memory and populates it. The address 1773of ``meminfo_t`` structure is updated in ``arg1`` of the entrypoint 1774information to BL2. 1775 1776Function : bl1_plat_fwu_done() [optional] 1777~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1778 1779:: 1780 1781 Argument : unsigned int image_id, uintptr_t image_src, 1782 unsigned int image_size 1783 Return : void 1784 1785BL1 calls this function when the FWU process is complete. It must not return. 1786The platform may override this function to take platform specific action, for 1787example to initiate the normal boot flow. 1788 1789The default implementation spins forever. 1790 1791Function : bl1_plat_mem_check() [mandatory] 1792~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1793 1794:: 1795 1796 Argument : uintptr_t mem_base, unsigned int mem_size, 1797 unsigned int flags 1798 Return : int 1799 1800BL1 calls this function while handling FWU related SMCs, more specifically when 1801copying or authenticating an image. Its responsibility is to ensure that the 1802region of memory identified by ``mem_base`` and ``mem_size`` is mapped in BL1, and 1803that this memory corresponds to either a secure or non-secure memory region as 1804indicated by the security state of the ``flags`` argument. 1805 1806This function can safely assume that the value resulting from the addition of 1807``mem_base`` and ``mem_size`` fits into a ``uintptr_t`` type variable and does not 1808overflow. 1809 1810This function must return 0 on success, a non-null error code otherwise. 1811 1812The default implementation of this function asserts therefore platforms must 1813override it when using the FWU feature. 1814 1815Boot Loader Stage 2 (BL2) 1816------------------------- 1817 1818The BL2 stage is executed only by the primary CPU, which is determined in BL1 1819using the ``platform_is_primary_cpu()`` function. BL1 passed control to BL2 at 1820``BL2_BASE``. BL2 executes in Secure EL1 and and invokes 1821``plat_get_bl_image_load_info()`` to retrieve the list of images to load from 1822non-volatile storage to secure/non-secure RAM. After all the images are loaded 1823then BL2 invokes ``plat_get_next_bl_params()`` to get the list of executable 1824images to be passed to the next BL image. 1825 1826The following functions must be implemented by the platform port to enable BL2 1827to perform the above tasks. 1828 1829Function : bl2_early_platform_setup2() [mandatory] 1830~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1831 1832:: 1833 1834 Argument : u_register_t, u_register_t, u_register_t, u_register_t 1835 Return : void 1836 1837This function executes with the MMU and data caches disabled. It is only called 1838by the primary CPU. The 4 arguments are passed by BL1 to BL2 and these arguments 1839are platform specific. 1840 1841On Arm standard platforms, the arguments received are : 1842 1843 arg0 - Points to load address of FW_CONFIG 1844 1845 arg1 - ``meminfo`` structure populated by BL1. The platform copies 1846 the contents of ``meminfo`` as it may be subsequently overwritten by BL2. 1847 1848On Arm standard platforms, this function also: 1849 1850- Initializes a UART (PL011 console), which enables access to the ``printf`` 1851 family of functions in BL2. 1852 1853- Initializes the storage abstraction layer used to load further bootloader 1854 images. It is necessary to do this early on platforms with a SCP_BL2 image, 1855 since the later ``bl2_platform_setup`` must be done after SCP_BL2 is loaded. 1856 1857Function : bl2_plat_arch_setup() [mandatory] 1858~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1859 1860:: 1861 1862 Argument : void 1863 Return : void 1864 1865This function executes with the MMU and data caches disabled. It is only called 1866by the primary CPU. 1867 1868The purpose of this function is to perform any architectural initialization 1869that varies across platforms. 1870 1871On Arm standard platforms, this function enables the MMU. 1872 1873Function : bl2_platform_setup() [mandatory] 1874~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1875 1876:: 1877 1878 Argument : void 1879 Return : void 1880 1881This function may execute with the MMU and data caches enabled if the platform 1882port does the necessary initialization in ``bl2_plat_arch_setup()``. It is only 1883called by the primary CPU. 1884 1885The purpose of this function is to perform any platform initialization 1886specific to BL2. 1887 1888In Arm standard platforms, this function performs security setup, including 1889configuration of the TrustZone controller to allow non-secure masters access 1890to most of DRAM. Part of DRAM is reserved for secure world use. 1891 1892Function : bl2_plat_handle_pre_image_load() [optional] 1893~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1894 1895:: 1896 1897 Argument : unsigned int 1898 Return : int 1899 1900This function can be used by the platforms to update/use image information 1901for given ``image_id``. This function is currently invoked in BL2 before 1902loading each image. 1903 1904Function : bl2_plat_handle_post_image_load() [optional] 1905~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1906 1907:: 1908 1909 Argument : unsigned int 1910 Return : int 1911 1912This function can be used by the platforms to update/use image information 1913for given ``image_id``. This function is currently invoked in BL2 after 1914loading each image. 1915 1916Function : bl2_plat_preload_setup [optional] 1917~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1918 1919:: 1920 1921 Argument : void 1922 Return : void 1923 1924This optional function performs any BL2 platform initialization 1925required before image loading, that is not done later in 1926bl2_platform_setup(). 1927 1928Boot Loader Stage 2 (BL2) at EL3 1929-------------------------------- 1930 1931When the platform has a non-TF-A Boot ROM it is desirable to jump 1932directly to BL2 instead of TF-A BL1. In this case BL2 is expected to 1933execute at EL3 instead of executing at EL1. Refer to the :ref:`Firmware Design` 1934document for more information. 1935 1936All mandatory functions of BL2 must be implemented, except the functions 1937bl2_early_platform_setup and bl2_el3_plat_arch_setup, because 1938their work is done now by bl2_el3_early_platform_setup and 1939bl2_el3_plat_arch_setup. These functions should generally implement 1940the bl1_plat_xxx() and bl2_plat_xxx() functionality combined. 1941 1942 1943Function : bl2_el3_early_platform_setup() [mandatory] 1944~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1945 1946:: 1947 1948 Argument : u_register_t, u_register_t, u_register_t, u_register_t 1949 Return : void 1950 1951This function executes with the MMU and data caches disabled. It is only called 1952by the primary CPU. This function receives four parameters which can be used 1953by the platform to pass any needed information from the Boot ROM to BL2. 1954 1955On Arm standard platforms, this function does the following: 1956 1957- Initializes a UART (PL011 console), which enables access to the ``printf`` 1958 family of functions in BL2. 1959 1960- Initializes the storage abstraction layer used to load further bootloader 1961 images. It is necessary to do this early on platforms with a SCP_BL2 image, 1962 since the later ``bl2_platform_setup`` must be done after SCP_BL2 is loaded. 1963 1964- Initializes the private variables that define the memory layout used. 1965 1966Function : bl2_el3_plat_arch_setup() [mandatory] 1967~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1968 1969:: 1970 1971 Argument : void 1972 Return : void 1973 1974This function executes with the MMU and data caches disabled. It is only called 1975by the primary CPU. 1976 1977The purpose of this function is to perform any architectural initialization 1978that varies across platforms. 1979 1980On Arm standard platforms, this function enables the MMU. 1981 1982Function : bl2_el3_plat_prepare_exit() [optional] 1983~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1984 1985:: 1986 1987 Argument : void 1988 Return : void 1989 1990This function is called prior to exiting BL2 and run the next image. 1991It should be used to perform platform specific clean up or bookkeeping 1992operations before transferring control to the next image. This function 1993runs with MMU disabled. 1994 1995FWU Boot Loader Stage 2 (BL2U) 1996------------------------------ 1997 1998The AP Firmware Updater Configuration, BL2U, is an optional part of the FWU 1999process and is executed only by the primary CPU. BL1 passes control to BL2U at 2000``BL2U_BASE``. BL2U executes in Secure-EL1 and is responsible for: 2001 2002#. (Optional) Transferring the optional SCP_BL2U binary image from AP secure 2003 memory to SCP RAM. BL2U uses the SCP_BL2U ``image_info`` passed by BL1. 2004 ``SCP_BL2U_BASE`` defines the address in AP secure memory where SCP_BL2U 2005 should be copied from. Subsequent handling of the SCP_BL2U image is 2006 implemented by the platform specific ``bl2u_plat_handle_scp_bl2u()`` function. 2007 If ``SCP_BL2U_BASE`` is not defined then this step is not performed. 2008 2009#. Any platform specific setup required to perform the FWU process. For 2010 example, Arm standard platforms initialize the TZC controller so that the 2011 normal world can access DDR memory. 2012 2013The following functions must be implemented by the platform port to enable 2014BL2U to perform the tasks mentioned above. 2015 2016Function : bl2u_early_platform_setup() [mandatory] 2017~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2018 2019:: 2020 2021 Argument : meminfo *mem_info, void *plat_info 2022 Return : void 2023 2024This function executes with the MMU and data caches disabled. It is only 2025called by the primary CPU. The arguments to this function is the address 2026of the ``meminfo`` structure and platform specific info provided by BL1. 2027 2028The platform may copy the contents of the ``mem_info`` and ``plat_info`` into 2029private storage as the original memory may be subsequently overwritten by BL2U. 2030 2031On Arm CSS platforms ``plat_info`` is interpreted as an ``image_info_t`` structure, 2032to extract SCP_BL2U image information, which is then copied into a private 2033variable. 2034 2035Function : bl2u_plat_arch_setup() [mandatory] 2036~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2037 2038:: 2039 2040 Argument : void 2041 Return : void 2042 2043This function executes with the MMU and data caches disabled. It is only 2044called by the primary CPU. 2045 2046The purpose of this function is to perform any architectural initialization 2047that varies across platforms, for example enabling the MMU (since the memory 2048map differs across platforms). 2049 2050Function : bl2u_platform_setup() [mandatory] 2051~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2052 2053:: 2054 2055 Argument : void 2056 Return : void 2057 2058This function may execute with the MMU and data caches enabled if the platform 2059port does the necessary initialization in ``bl2u_plat_arch_setup()``. It is only 2060called by the primary CPU. 2061 2062The purpose of this function is to perform any platform initialization 2063specific to BL2U. 2064 2065In Arm standard platforms, this function performs security setup, including 2066configuration of the TrustZone controller to allow non-secure masters access 2067to most of DRAM. Part of DRAM is reserved for secure world use. 2068 2069Function : bl2u_plat_handle_scp_bl2u() [optional] 2070~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2071 2072:: 2073 2074 Argument : void 2075 Return : int 2076 2077This function is used to perform any platform-specific actions required to 2078handle the SCP firmware. Typically it transfers the image into SCP memory using 2079a platform-specific protocol and waits until SCP executes it and signals to the 2080Application Processor (AP) for BL2U execution to continue. 2081 2082This function returns 0 on success, a negative error code otherwise. 2083This function is included if SCP_BL2U_BASE is defined. 2084 2085Boot Loader Stage 3-1 (BL31) 2086---------------------------- 2087 2088During cold boot, the BL31 stage is executed only by the primary CPU. This is 2089determined in BL1 using the ``platform_is_primary_cpu()`` function. BL1 passes 2090control to BL31 at ``BL31_BASE``. During warm boot, BL31 is executed by all 2091CPUs. BL31 executes at EL3 and is responsible for: 2092 2093#. Re-initializing all architectural and platform state. Although BL1 performs 2094 some of this initialization, BL31 remains resident in EL3 and must ensure 2095 that EL3 architectural and platform state is completely initialized. It 2096 should make no assumptions about the system state when it receives control. 2097 2098#. Passing control to a normal world BL image, pre-loaded at a platform- 2099 specific address by BL2. On ARM platforms, BL31 uses the ``bl_params`` list 2100 populated by BL2 in memory to do this. 2101 2102#. Providing runtime firmware services. Currently, BL31 only implements a 2103 subset of the Power State Coordination Interface (PSCI) API as a runtime 2104 service. See :ref:`psci_in_bl31` below for details of porting the PSCI 2105 implementation. 2106 2107#. Optionally passing control to the BL32 image, pre-loaded at a platform- 2108 specific address by BL2. BL31 exports a set of APIs that allow runtime 2109 services to specify the security state in which the next image should be 2110 executed and run the corresponding image. On ARM platforms, BL31 uses the 2111 ``bl_params`` list populated by BL2 in memory to do this. 2112 2113If BL31 is a reset vector, It also needs to handle the reset as specified in 2114section 2.2 before the tasks described above. 2115 2116The following functions must be implemented by the platform port to enable BL31 2117to perform the above tasks. 2118 2119Function : bl31_early_platform_setup2() [mandatory] 2120~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2121 2122:: 2123 2124 Argument : u_register_t, u_register_t, u_register_t, u_register_t 2125 Return : void 2126 2127This function executes with the MMU and data caches disabled. It is only called 2128by the primary CPU. BL2 can pass 4 arguments to BL31 and these arguments are 2129platform specific. 2130 2131In Arm standard platforms, the arguments received are : 2132 2133 arg0 - The pointer to the head of `bl_params_t` list 2134 which is list of executable images following BL31, 2135 2136 arg1 - Points to load address of SOC_FW_CONFIG if present 2137 except in case of Arm FVP and Juno platform. 2138 2139 In case of Arm FVP and Juno platform, points to load address 2140 of FW_CONFIG. 2141 2142 arg2 - Points to load address of HW_CONFIG if present 2143 2144 arg3 - A special value to verify platform parameters from BL2 to BL31. Not 2145 used in release builds. 2146 2147The function runs through the `bl_param_t` list and extracts the entry point 2148information for BL32 and BL33. It also performs the following: 2149 2150- Initialize a UART (PL011 console), which enables access to the ``printf`` 2151 family of functions in BL31. 2152 2153- Enable issuing of snoop and DVM (Distributed Virtual Memory) requests to the 2154 CCI slave interface corresponding to the cluster that includes the primary 2155 CPU. 2156 2157Function : bl31_plat_arch_setup() [mandatory] 2158~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2159 2160:: 2161 2162 Argument : void 2163 Return : void 2164 2165This function executes with the MMU and data caches disabled. It is only called 2166by the primary CPU. 2167 2168The purpose of this function is to perform any architectural initialization 2169that varies across platforms. 2170 2171On Arm standard platforms, this function enables the MMU. 2172 2173Function : bl31_platform_setup() [mandatory] 2174~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2175 2176:: 2177 2178 Argument : void 2179 Return : void 2180 2181This function may execute with the MMU and data caches enabled if the platform 2182port does the necessary initialization in ``bl31_plat_arch_setup()``. It is only 2183called by the primary CPU. 2184 2185The purpose of this function is to complete platform initialization so that both 2186BL31 runtime services and normal world software can function correctly. 2187 2188On Arm standard platforms, this function does the following: 2189 2190- Initialize the generic interrupt controller. 2191 2192 Depending on the GIC driver selected by the platform, the appropriate GICv2 2193 or GICv3 initialization will be done, which mainly consists of: 2194 2195 - Enable secure interrupts in the GIC CPU interface. 2196 - Disable the legacy interrupt bypass mechanism. 2197 - Configure the priority mask register to allow interrupts of all priorities 2198 to be signaled to the CPU interface. 2199 - Mark SGIs 8-15 and the other secure interrupts on the platform as secure. 2200 - Target all secure SPIs to CPU0. 2201 - Enable these secure interrupts in the GIC distributor. 2202 - Configure all other interrupts as non-secure. 2203 - Enable signaling of secure interrupts in the GIC distributor. 2204 2205- Enable system-level implementation of the generic timer counter through the 2206 memory mapped interface. 2207 2208- Grant access to the system counter timer module 2209 2210- Initialize the power controller device. 2211 2212 In particular, initialise the locks that prevent concurrent accesses to the 2213 power controller device. 2214 2215Function : bl31_plat_runtime_setup() [optional] 2216~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2217 2218:: 2219 2220 Argument : void 2221 Return : void 2222 2223The purpose of this function is allow the platform to perform any BL31 runtime 2224setup just prior to BL31 exit during cold boot. The default weak 2225implementation of this function will invoke ``console_switch_state()`` to switch 2226console output to consoles marked for use in the ``runtime`` state. 2227 2228Function : bl31_plat_get_next_image_ep_info() [mandatory] 2229~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2230 2231:: 2232 2233 Argument : uint32_t 2234 Return : entry_point_info * 2235 2236This function may execute with the MMU and data caches enabled if the platform 2237port does the necessary initializations in ``bl31_plat_arch_setup()``. 2238 2239This function is called by ``bl31_main()`` to retrieve information provided by 2240BL2 for the next image in the security state specified by the argument. BL31 2241uses this information to pass control to that image in the specified security 2242state. This function must return a pointer to the ``entry_point_info`` structure 2243(that was copied during ``bl31_early_platform_setup()``) if the image exists. It 2244should return NULL otherwise. 2245 2246Function : plat_rmmd_get_cca_attest_token() [mandatory when ENABLE_RME == 1] 2247~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2248 2249:: 2250 2251 Argument : uintptr_t, size_t *, uintptr_t, size_t, size_t * 2252 Return : int 2253 2254This function returns the Platform attestation token. If the full token does 2255not fit in the buffer, the function will return a hunk of the token and 2256indicate how many bytes were copied and how many are pending. Multiple calls 2257to this function may be needed to retrieve the entire token. 2258 2259The parameters of the function are: 2260 2261 arg0 - A pointer to the buffer where the Platform token should be copied by 2262 this function. If the platform token does not completely fit in the 2263 buffer, the function may return a piece of the token only. 2264 2265 arg1 - Contains the size (in bytes) of the buffer passed in arg0. In 2266 addition, this parameter is used by the function to return the size 2267 of the platform token length hunk copied to the buffer. 2268 2269 arg2 - A pointer to the buffer where the challenge object is stored. 2270 2271 arg3 - The length of the challenge object in bytes. Possible values are 32, 2272 48 and 64. This argument must be zero for subsequent calls to 2273 retrieve the remaining hunks of the token. 2274 2275 arg4 - Returns the remaining length of the token (in bytes) that is yet to 2276 be returned in further calls. 2277 2278The function returns 0 on success, -EINVAL on failure and -EAGAIN if the 2279resource associated with the platform token retrieval is busy. 2280 2281Function : plat_rmmd_get_cca_realm_attest_key() [mandatory when ENABLE_RME == 1] 2282~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2283 2284:: 2285 2286 Argument : uintptr_t, size_t *, unsigned int 2287 Return : int 2288 2289This function returns the delegated realm attestation key which will be used to 2290sign Realm attestation token. The API currently only supports P-384 ECC curve 2291key. 2292 2293The parameters of the function are: 2294 2295 arg0 - A pointer to the buffer where the attestation key should be copied 2296 by this function. The buffer must be big enough to hold the 2297 attestation key. 2298 2299 arg1 - Contains the size (in bytes) of the buffer passed in arg0. The 2300 function returns the attestation key length in this parameter. 2301 2302 arg2 - The type of the elliptic curve to which the requested attestation key 2303 belongs. 2304 2305The function returns 0 on success, -EINVAL on failure. 2306 2307Function : plat_rmmd_get_el3_rmm_shared_mem() [when ENABLE_RME == 1] 2308~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2309 2310:: 2311 2312 Argument : uintptr_t * 2313 Return : size_t 2314 2315This function returns the size of the shared area between EL3 and RMM (or 0 on 2316failure). A pointer to the shared area (or a NULL pointer on failure) is stored 2317in the pointer passed as argument. 2318 2319Function : plat_rmmd_load_manifest() [when ENABLE_RME == 1] 2320~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2321 2322:: 2323 2324 Arguments : rmm_manifest_t *manifest 2325 Return : int 2326 2327When ENABLE_RME is enabled, this function populates a boot manifest for the 2328RMM image and stores it in the area specified by manifest. 2329 2330When ENABLE_RME is disabled, this function is not used. 2331 2332Function : plat_rmmd_el3_token_sign_push_req() [mandatory when RMMD_ENABLE_EL3_TOKEN_SIGN == 1] 2333~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2334 2335:: 2336 2337 Arguments : const struct el3_token_sign_request *req 2338 Return : int 2339 2340Queue realm attestation token signing request from the RMM in EL3. The interface between 2341the RMM and EL3 is modeled as a queue but the underlying implementation may be different, 2342so long as the semantics of queuing and the error codes are used as defined below. 2343 2344See :ref:`el3_token_sign_request_struct` for definition of the request structure. 2345 2346Optional interface from the RMM-EL3 interface v0.4 onwards. 2347 2348The parameters of the functions are: 2349 arg0: Pointer to the token sign request to be pushed to EL3. 2350 The structure must be located in the RMM-EL3 shared 2351 memory buffer and must be locked before use. 2352 2353Return codes: 2354 - E_RMM_OK On Success. 2355 - E_RMM_INVAL If the arguments are invalid. 2356 - E_RMM_AGAIN Indicates that the request was not queued since the 2357 queue in EL3 is full. This may also be returned for any reason 2358 or situation in the system, that prevents accepting the request 2359 from the RMM. 2360 - E_RMM_UNK If the SMC is not implemented or if interface 2361 version is < 0.4. 2362 2363Function : plat_rmmd_el3_token_sign_pull_resp() [mandatory when RMMD_ENABLE_EL3_TOKEN_SIGN == 1] 2364~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2365 2366:: 2367 2368 Arguments : struct el3_token_sign_response *resp 2369 Return : int 2370 2371Populate the attestation signing response in the ``resp`` parameter. The interface between 2372the RMM and EL3 is modeled as a queue for responses but the underlying implementation may 2373be different, so long as the semantics of queuing and the error codes are used as defined 2374below. 2375 2376See :ref:`el3_token_sign_response_struct` for definition of the response structure. 2377 2378Optional interface from the RMM-EL3 interface v0.4 onwards. 2379 2380The parameters of the functions are: 2381 resp: Pointer to the token sign response to get from EL3. 2382 The structure must be located in the RMM-EL3 shared 2383 memory buffer and must be locked before use. 2384 2385Return: 2386 - E_RMM_OK On Success. 2387 - E_RMM_INVAL If the arguments are invalid. 2388 - E_RMM_AGAIN Indicates that a response is not ready yet. 2389 - E_RMM_UNK If the SMC is not implemented or if interface 2390 version is < 0.4. 2391 2392Function : plat_rmmd_el3_token_sign_get_rak_pub() [mandatory when RMMD_ENABLE_EL3_TOKEN_SIGN == 1] 2393~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2394 2395:: 2396 2397 Argument : uintptr_t, size_t *, unsigned int 2398 Return : int 2399 2400This function returns the public portion of the realm attestation key which will be used to 2401sign Realm attestation token. Typically, with delegated attestation, the private key is 2402returned, however, there may be platforms where the private key bits are better protected 2403in a platform specific manner such that the private key is not exposed. In such cases, 2404the RMM will only cache the public key and forward any requests such as signing, that 2405uses the private key to EL3. The API currently only supports P-384 ECC curve key. 2406 2407This is an optional interface from the RMM-EL3 interface v0.4 onwards. 2408 2409The parameters of the function are: 2410 2411 arg0 - A pointer to the buffer where the public key should be copied 2412 by this function. The buffer must be big enough to hold the 2413 attestation key. 2414 2415 arg1 - Contains the size (in bytes) of the buffer passed in arg0. The 2416 function returns the attestation key length in this parameter. 2417 2418 arg2 - The type of the elliptic curve to which the requested attestation key 2419 belongs. 2420 2421The function returns E_RMM_OK on success, RMM_E_INVAL if arguments are invalid and 2422E_RMM_UNK if the SMC is not implemented or if interface version is < 0.4. 2423 2424Function : bl31_plat_enable_mmu [optional] 2425~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2426 2427:: 2428 2429 Argument : uint32_t 2430 Return : void 2431 2432This function enables the MMU. The boot code calls this function with MMU and 2433caches disabled. This function should program necessary registers to enable 2434translation, and upon return, the MMU on the calling PE must be enabled. 2435 2436The function must honor flags passed in the first argument. These flags are 2437defined by the translation library, and can be found in the file 2438``include/lib/xlat_tables/xlat_mmu_helpers.h``. 2439 2440On DynamIQ systems, this function must not use stack while enabling MMU, which 2441is how the function in xlat table library version 2 is implemented. 2442 2443Function : plat_init_apkey [optional] 2444~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2445 2446:: 2447 2448 Argument : void 2449 Return : uint128_t 2450 2451This function returns the 128-bit value which can be used to program ARMv8.3 2452pointer authentication keys. 2453 2454The value should be obtained from a reliable source of randomness. 2455 2456This function is only needed if ARMv8.3 pointer authentication is used in the 2457Trusted Firmware by building with ``BRANCH_PROTECTION`` option set to non-zero. 2458 2459Function : plat_get_syscnt_freq2() [mandatory] 2460~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2461 2462:: 2463 2464 Argument : void 2465 Return : unsigned int 2466 2467This function is used by the architecture setup code to retrieve the counter 2468frequency for the CPU's generic timer. This value will be programmed into the 2469``CNTFRQ_EL0`` register. In Arm standard platforms, it returns the base frequency 2470of the system counter, which is retrieved from the first entry in the frequency 2471modes table. 2472 2473#define : PLAT_PERCPU_BAKERY_LOCK_SIZE [optional] 2474~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2475 2476When ``USE_COHERENT_MEM = 0``, this constant defines the total memory (in 2477bytes) aligned to the cache line boundary that should be allocated per-cpu to 2478accommodate all the bakery locks. 2479 2480If this constant is not defined when ``USE_COHERENT_MEM = 0``, the linker 2481calculates the size of the ``.bakery_lock`` input section, aligns it to the 2482nearest ``CACHE_WRITEBACK_GRANULE``, multiplies it with ``PLATFORM_CORE_COUNT`` 2483and stores the result in a linker symbol. This constant prevents a platform 2484from relying on the linker and provide a more efficient mechanism for 2485accessing per-cpu bakery lock information. 2486 2487If this constant is defined and its value is not equal to the value 2488calculated by the linker then a link time assertion is raised. A compile time 2489assertion is raised if the value of the constant is not aligned to the cache 2490line boundary. 2491 2492.. _porting_guide_sdei_requirements: 2493 2494SDEI porting requirements 2495~~~~~~~~~~~~~~~~~~~~~~~~~ 2496 2497The |SDEI| dispatcher requires the platform to provide the following macros 2498and functions, of which some are optional, and some others mandatory. 2499 2500Macros 2501...... 2502 2503Macro: PLAT_SDEI_NORMAL_PRI [mandatory] 2504^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 2505 2506This macro must be defined to the EL3 exception priority level associated with 2507Normal |SDEI| events on the platform. This must have a higher value 2508(therefore of lower priority) than ``PLAT_SDEI_CRITICAL_PRI``. 2509 2510Macro: PLAT_SDEI_CRITICAL_PRI [mandatory] 2511^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 2512 2513This macro must be defined to the EL3 exception priority level associated with 2514Critical |SDEI| events on the platform. This must have a lower value 2515(therefore of higher priority) than ``PLAT_SDEI_NORMAL_PRI``. 2516 2517**Note**: |SDEI| exception priorities must be the lowest among Secure 2518priorities. Among the |SDEI| exceptions, Critical |SDEI| priority must 2519be higher than Normal |SDEI| priority. 2520 2521Functions 2522......... 2523 2524Function: int plat_sdei_validate_entry_point() [optional] 2525^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 2526 2527:: 2528 2529 Argument: uintptr_t ep, unsigned int client_mode 2530 Return: int 2531 2532This function validates the entry point address of the event handler provided by 2533the client for both event registration and *Complete and Resume* |SDEI| calls. 2534The function ensures that the address is valid in the client translation regime. 2535 2536The second argument is the exception level that the client is executing in. It 2537can be Non-Secure EL1 or Non-Secure EL2. 2538 2539The function must return ``0`` for successful validation, or ``-1`` upon failure. 2540 2541The default implementation always returns ``0``. On Arm platforms, this function 2542translates the entry point address within the client translation regime and 2543further ensures that the resulting physical address is located in Non-secure 2544DRAM. 2545 2546Function: void plat_sdei_handle_masked_trigger(uint64_t mpidr, unsigned int intr) [optional] 2547^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 2548 2549:: 2550 2551 Argument: uint64_t 2552 Argument: unsigned int 2553 Return: void 2554 2555|SDEI| specification requires that a PE comes out of reset with the events 2556masked. The client therefore is expected to call ``PE_UNMASK`` to unmask 2557|SDEI| events on the PE. No |SDEI| events can be dispatched until such 2558time. 2559 2560Should a PE receive an interrupt that was bound to an |SDEI| event while the 2561events are masked on the PE, the dispatcher implementation invokes the function 2562``plat_sdei_handle_masked_trigger``. The MPIDR of the PE that received the 2563interrupt and the interrupt ID are passed as parameters. 2564 2565The default implementation only prints out a warning message. 2566 2567.. _porting_guide_trng_requirements: 2568 2569TRNG porting requirements 2570~~~~~~~~~~~~~~~~~~~~~~~~~ 2571 2572The |TRNG| backend requires the platform to provide the following values 2573and mandatory functions. 2574 2575Values 2576...... 2577 2578value: uuid_t plat_trng_uuid [mandatory] 2579^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 2580 2581This value must be defined to the UUID of the TRNG backend that is specific to 2582the hardware after ``plat_entropy_setup`` function is called. This value must 2583conform to the SMCCC calling convention; The most significant 32 bits of the 2584UUID must not equal ``0xffffffff`` or the signed integer ``-1`` as this value in 2585w0 indicates failure to get a TRNG source. 2586 2587Functions 2588......... 2589 2590Function: void plat_entropy_setup(void) [mandatory] 2591^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 2592 2593:: 2594 2595 Argument: none 2596 Return: none 2597 2598This function is expected to do platform-specific initialization of any TRNG 2599hardware. This may include generating a UUID from a hardware-specific seed. 2600 2601Function: bool plat_get_entropy(uint64_t \*out) [mandatory] 2602^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 2603 2604:: 2605 2606 Argument: uint64_t * 2607 Return: bool 2608 Out : when the return value is true, the entropy has been written into the 2609 storage pointed to 2610 2611This function writes entropy into storage provided by the caller. If no entropy 2612is available, it must return false and the storage must not be written. 2613 2614.. _psci_in_bl31: 2615 2616Power State Coordination Interface (in BL31) 2617-------------------------------------------- 2618 2619The TF-A implementation of the PSCI API is based around the concept of a 2620*power domain*. A *power domain* is a CPU or a logical group of CPUs which 2621share some state on which power management operations can be performed as 2622specified by `PSCI`_. Each CPU in the system is assigned a cpu index which is 2623a unique number between ``0`` and ``PLATFORM_CORE_COUNT - 1``. The 2624*power domains* are arranged in a hierarchical tree structure and each 2625*power domain* can be identified in a system by the cpu index of any CPU that 2626is part of that domain and a *power domain level*. A processing element (for 2627example, a CPU) is at level 0. If the *power domain* node above a CPU is a 2628logical grouping of CPUs that share some state, then level 1 is that group of 2629CPUs (for example, a cluster), and level 2 is a group of clusters (for 2630example, the system). More details on the power domain topology and its 2631organization can be found in :ref:`PSCI Power Domain Tree Structure`. 2632 2633BL31's platform initialization code exports a pointer to the platform-specific 2634power management operations required for the PSCI implementation to function 2635correctly. This information is populated in the ``plat_psci_ops`` structure. The 2636PSCI implementation calls members of the ``plat_psci_ops`` structure for performing 2637power management operations on the power domains. For example, the target 2638CPU is specified by its ``MPIDR`` in a PSCI ``CPU_ON`` call. The ``pwr_domain_on()`` 2639handler (if present) is called for the CPU power domain. 2640 2641The ``power-state`` parameter of a PSCI ``CPU_SUSPEND`` call can be used to 2642describe composite power states specific to a platform. The PSCI implementation 2643defines a generic representation of the power-state parameter, which is an 2644array of local power states where each index corresponds to a power domain 2645level. Each entry contains the local power state the power domain at that power 2646level could enter. It depends on the ``validate_power_state()`` handler to 2647convert the power-state parameter (possibly encoding a composite power state) 2648passed in a PSCI ``CPU_SUSPEND`` call to this representation. 2649 2650The following functions form part of platform port of PSCI functionality. 2651 2652Function : plat_psci_stat_accounting_start() [optional] 2653~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2654 2655:: 2656 2657 Argument : const psci_power_state_t * 2658 Return : void 2659 2660This is an optional hook that platforms can implement for residency statistics 2661accounting before entering a low power state. The ``pwr_domain_state`` field of 2662``state_info`` (first argument) can be inspected if stat accounting is done 2663differently at CPU level versus higher levels. As an example, if the element at 2664index 0 (CPU power level) in the ``pwr_domain_state`` array indicates a power down 2665state, special hardware logic may be programmed in order to keep track of the 2666residency statistics. For higher levels (array indices > 0), the residency 2667statistics could be tracked in software using PMF. If ``ENABLE_PMF`` is set, the 2668default implementation will use PMF to capture timestamps. 2669 2670Function : plat_psci_stat_accounting_stop() [optional] 2671~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2672 2673:: 2674 2675 Argument : const psci_power_state_t * 2676 Return : void 2677 2678This is an optional hook that platforms can implement for residency statistics 2679accounting after exiting from a low power state. The ``pwr_domain_state`` field 2680of ``state_info`` (first argument) can be inspected if stat accounting is done 2681differently at CPU level versus higher levels. As an example, if the element at 2682index 0 (CPU power level) in the ``pwr_domain_state`` array indicates a power down 2683state, special hardware logic may be programmed in order to keep track of the 2684residency statistics. For higher levels (array indices > 0), the residency 2685statistics could be tracked in software using PMF. If ``ENABLE_PMF`` is set, the 2686default implementation will use PMF to capture timestamps. 2687 2688Function : plat_psci_stat_get_residency() [optional] 2689~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2690 2691:: 2692 2693 Argument : unsigned int, const psci_power_state_t *, unsigned int 2694 Return : u_register_t 2695 2696This is an optional interface that is is invoked after resuming from a low power 2697state and provides the time spent resident in that low power state by the power 2698domain at a particular power domain level. When a CPU wakes up from suspend, 2699all its parent power domain levels are also woken up. The generic PSCI code 2700invokes this function for each parent power domain that is resumed and it 2701identified by the ``lvl`` (first argument) parameter. The ``state_info`` (second 2702argument) describes the low power state that the power domain has resumed from. 2703The current CPU is the first CPU in the power domain to resume from the low 2704power state and the ``last_cpu_idx`` (third parameter) is the index of the last 2705CPU in the power domain to suspend and may be needed to calculate the residency 2706for that power domain. 2707 2708Function : plat_get_target_pwr_state() [optional] 2709~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2710 2711:: 2712 2713 Argument : unsigned int, const plat_local_state_t *, unsigned int 2714 Return : plat_local_state_t 2715 2716The PSCI generic code uses this function to let the platform participate in 2717state coordination during a power management operation. The function is passed 2718a pointer to an array of platform specific local power state ``states`` (second 2719argument) which contains the requested power state for each CPU at a particular 2720power domain level ``lvl`` (first argument) within the power domain. The function 2721is expected to traverse this array of upto ``ncpus`` (third argument) and return 2722a coordinated target power state by the comparing all the requested power 2723states. The target power state should not be deeper than any of the requested 2724power states. 2725 2726A weak definition of this API is provided by default wherein it assumes 2727that the platform assigns a local state value in order of increasing depth 2728of the power state i.e. for two power states X & Y, if X < Y 2729then X represents a shallower power state than Y. As a result, the 2730coordinated target local power state for a power domain will be the minimum 2731of the requested local power state values. 2732 2733Function : plat_get_power_domain_tree_desc() [mandatory] 2734~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2735 2736:: 2737 2738 Argument : void 2739 Return : const unsigned char * 2740 2741This function returns a pointer to the byte array containing the power domain 2742topology tree description. The format and method to construct this array are 2743described in :ref:`PSCI Power Domain Tree Structure`. The BL31 PSCI 2744initialization code requires this array to be described by the platform, either 2745statically or dynamically, to initialize the power domain topology tree. In case 2746the array is populated dynamically, then plat_core_pos_by_mpidr() and 2747plat_my_core_pos() should also be implemented suitably so that the topology tree 2748description matches the CPU indices returned by these APIs. These APIs together 2749form the platform interface for the PSCI topology framework. 2750 2751Function : plat_setup_psci_ops() [mandatory] 2752~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2753 2754:: 2755 2756 Argument : uintptr_t, const plat_psci_ops ** 2757 Return : int 2758 2759This function may execute with the MMU and data caches enabled if the platform 2760port does the necessary initializations in ``bl31_plat_arch_setup()``. It is only 2761called by the primary CPU. 2762 2763This function is called by PSCI initialization code. Its purpose is to let 2764the platform layer know about the warm boot entrypoint through the 2765``sec_entrypoint`` (first argument) and to export handler routines for 2766platform-specific psci power management actions by populating the passed 2767pointer with a pointer to BL31's private ``plat_psci_ops`` structure. 2768 2769A description of each member of this structure is given below. Please refer to 2770the Arm FVP specific implementation of these handlers in 2771``plat/arm/board/fvp/fvp_pm.c`` as an example. For each PSCI function that the 2772platform wants to support, the associated operation or operations in this 2773structure must be provided and implemented (Refer section 4 of 2774:ref:`Firmware Design` for the PSCI API supported in TF-A). To disable a PSCI 2775function in a platform port, the operation should be removed from this 2776structure instead of providing an empty implementation. 2777 2778plat_psci_ops.cpu_standby() 2779........................... 2780 2781Perform the platform-specific actions to enter the standby state for a cpu 2782indicated by the passed argument. This provides a fast path for CPU standby 2783wherein overheads of PSCI state management and lock acquisition is avoided. 2784For this handler to be invoked by the PSCI ``CPU_SUSPEND`` API implementation, 2785the suspend state type specified in the ``power-state`` parameter should be 2786STANDBY and the target power domain level specified should be the CPU. The 2787handler should put the CPU into a low power retention state (usually by 2788issuing a wfi instruction) and ensure that it can be woken up from that 2789state by a normal interrupt. The generic code expects the handler to succeed. 2790 2791plat_psci_ops.pwr_domain_on() 2792............................. 2793 2794Perform the platform specific actions to power on a CPU, specified 2795by the ``MPIDR`` (first argument). The generic code expects the platform to 2796return PSCI_E_SUCCESS on success or PSCI_E_INTERN_FAIL for any failure. 2797 2798plat_psci_ops.pwr_domain_off_early() [optional] 2799............................................... 2800 2801This optional function performs the platform specific actions to check if 2802powering off the calling CPU and its higher parent power domain levels as 2803indicated by the ``target_state`` (first argument) is possible or allowed. 2804 2805The ``target_state`` encodes the platform coordinated target local power states 2806for the CPU power domain and its parent power domain levels. 2807 2808For this handler, the local power state for the CPU power domain will be a 2809power down state where as it could be either power down, retention or run state 2810for the higher power domain levels depending on the result of state 2811coordination. The generic code expects PSCI_E_DENIED return code if the 2812platform thinks that CPU_OFF should not proceed on the calling CPU. 2813 2814plat_psci_ops.pwr_domain_off() 2815.............................. 2816 2817Perform the platform specific actions to prepare to power off the calling CPU 2818and its higher parent power domain levels as indicated by the ``target_state`` 2819(first argument). It is called by the PSCI ``CPU_OFF`` API implementation. 2820 2821The ``target_state`` encodes the platform coordinated target local power states 2822for the CPU power domain and its parent power domain levels. The handler 2823needs to perform power management operation corresponding to the local state 2824at each power level. 2825 2826For this handler, the local power state for the CPU power domain will be a 2827power down state where as it could be either power down, retention or run state 2828for the higher power domain levels depending on the result of state 2829coordination. The generic code expects the handler to succeed. 2830 2831plat_psci_ops.pwr_domain_validate_suspend() [optional] 2832...................................................... 2833 2834This is an optional function that is only compiled into the build if the build 2835option ``PSCI_OS_INIT_MODE`` is enabled. 2836 2837If implemented, this function allows the platform to perform platform specific 2838validations based on hardware states. The generic code expects this function to 2839return PSCI_E_SUCCESS on success, or either PSCI_E_DENIED or 2840PSCI_E_INVALID_PARAMS as appropriate for any invalid requests. 2841 2842plat_psci_ops.pwr_domain_suspend_pwrdown_early() [optional] 2843........................................................... 2844 2845This optional function may be used as a performance optimization to replace 2846or complement pwr_domain_suspend() on some platforms. Its calling semantics 2847are identical to pwr_domain_suspend(), except the PSCI implementation only 2848calls this function when suspending to a power down state, and it guarantees 2849that data caches are enabled. 2850 2851When HW_ASSISTED_COHERENCY = 0, the PSCI implementation disables data caches 2852before calling pwr_domain_suspend(). If the target_state corresponds to a 2853power down state and it is safe to perform some or all of the platform 2854specific actions in that function with data caches enabled, it may be more 2855efficient to move those actions to this function. When HW_ASSISTED_COHERENCY 2856= 1, data caches remain enabled throughout, and so there is no advantage to 2857moving platform specific actions to this function. 2858 2859plat_psci_ops.pwr_domain_suspend() 2860.................................. 2861 2862Perform the platform specific actions to prepare to suspend the calling 2863CPU and its higher parent power domain levels as indicated by the 2864``target_state`` (first argument). It is called by the PSCI ``CPU_SUSPEND`` 2865API implementation. 2866 2867The ``target_state`` has a similar meaning as described in 2868the ``pwr_domain_off()`` operation. It encodes the platform coordinated 2869target local power states for the CPU power domain and its parent 2870power domain levels. The handler needs to perform power management operation 2871corresponding to the local state at each power level. The generic code 2872expects the handler to succeed. 2873 2874The difference between turning a power domain off versus suspending it is that 2875in the former case, the power domain is expected to re-initialize its state 2876when it is next powered on (see ``pwr_domain_on_finish()``). In the latter 2877case, the power domain is expected to save enough state so that it can resume 2878execution by restoring this state when its powered on (see 2879``pwr_domain_suspend_finish()``). 2880 2881When suspending a core, the platform can also choose to power off the GICv3 2882Redistributor and ITS through an implementation-defined sequence. To achieve 2883this safely, the ITS context must be saved first. The architectural part is 2884implemented by the ``gicv3_its_save_disable()`` helper, but most of the needed 2885sequence is implementation defined and it is therefore the responsibility of 2886the platform code to implement the necessary sequence. Then the GIC 2887Redistributor context can be saved using the ``gicv3_rdistif_save()`` helper. 2888Powering off the Redistributor requires the implementation to support it and it 2889is the responsibility of the platform code to execute the right implementation 2890defined sequence. 2891 2892When a system suspend is requested, the platform can also make use of the 2893``gicv3_distif_save()`` helper to save the context of the GIC Distributor after 2894it has saved the context of the Redistributors and ITS of all the cores in the 2895system. The context of the Distributor can be large and may require it to be 2896allocated in a special area if it cannot fit in the platform's global static 2897data, for example in DRAM. The Distributor can then be powered down using an 2898implementation-defined sequence. 2899 2900plat_psci_ops.pwr_domain_pwr_down_wfi() 2901....................................... 2902 2903This is an optional function and, if implemented, is expected to perform 2904platform specific actions including the ``wfi`` invocation which allows the 2905CPU to powerdown. Since this function is invoked outside the PSCI locks, 2906the actions performed in this hook must be local to the CPU or the platform 2907must ensure that races between multiple CPUs cannot occur. 2908 2909The ``target_state`` has a similar meaning as described in the ``pwr_domain_off()`` 2910operation and it encodes the platform coordinated target local power states for 2911the CPU power domain and its parent power domain levels. This function must 2912not return back to the caller (by calling wfi in an infinite loop to ensure 2913some CPUs power down mitigations work properly). 2914 2915If this function is not implemented by the platform, PSCI generic 2916implementation invokes ``psci_power_down_wfi()`` for power down. 2917 2918plat_psci_ops.pwr_domain_on_finish() 2919.................................... 2920 2921This function is called by the PSCI implementation after the calling CPU is 2922powered on and released from reset in response to an earlier PSCI ``CPU_ON`` call. 2923It performs the platform-specific setup required to initialize enough state for 2924this CPU to enter the normal world and also provide secure runtime firmware 2925services. 2926 2927The ``target_state`` (first argument) is the prior state of the power domains 2928immediately before the CPU was turned on. It indicates which power domains 2929above the CPU might require initialization due to having previously been in 2930low power states. The generic code expects the handler to succeed. 2931 2932plat_psci_ops.pwr_domain_on_finish_late() [optional] 2933........................................................... 2934 2935This optional function is called by the PSCI implementation after the calling 2936CPU is fully powered on with respective data caches enabled. The calling CPU and 2937the associated cluster are guaranteed to be participating in coherency. This 2938function gives the flexibility to perform any platform-specific actions safely, 2939such as initialization or modification of shared data structures, without the 2940overhead of explicit cache maintainace operations. 2941 2942The ``target_state`` has a similar meaning as described in the ``pwr_domain_on_finish()`` 2943operation. The generic code expects the handler to succeed. 2944 2945plat_psci_ops.pwr_domain_suspend_finish() 2946......................................... 2947 2948This function is called by the PSCI implementation after the calling CPU is 2949powered on and released from reset in response to an asynchronous wakeup 2950event, for example a timer interrupt that was programmed by the CPU during the 2951``CPU_SUSPEND`` call or ``SYSTEM_SUSPEND`` call. It performs the platform-specific 2952setup required to restore the saved state for this CPU to resume execution 2953in the normal world and also provide secure runtime firmware services. 2954 2955The ``target_state`` (first argument) has a similar meaning as described in 2956the ``pwr_domain_on_finish()`` operation. The generic code expects the platform 2957to succeed. 2958 2959If the Distributor, Redistributors or ITS have been powered off as part of a 2960suspend, their context must be restored in this function in the reverse order 2961to how they were saved during suspend sequence. 2962 2963plat_psci_ops.system_off() 2964.......................... 2965 2966This function is called by PSCI implementation in response to a ``SYSTEM_OFF`` 2967call. It performs the platform-specific system poweroff sequence after 2968notifying the Secure Payload Dispatcher. 2969 2970plat_psci_ops.system_reset() 2971............................ 2972 2973This function is called by PSCI implementation in response to a ``SYSTEM_RESET`` 2974call. It performs the platform-specific system reset sequence after 2975notifying the Secure Payload Dispatcher. 2976 2977plat_psci_ops.validate_power_state() 2978.................................... 2979 2980This function is called by the PSCI implementation during the ``CPU_SUSPEND`` 2981call to validate the ``power_state`` parameter of the PSCI API and if valid, 2982populate it in ``req_state`` (second argument) array as power domain level 2983specific local states. If the ``power_state`` is invalid, the platform must 2984return PSCI_E_INVALID_PARAMS as error, which is propagated back to the 2985normal world PSCI client. 2986 2987plat_psci_ops.validate_ns_entrypoint() 2988...................................... 2989 2990This function is called by the PSCI implementation during the ``CPU_SUSPEND``, 2991``SYSTEM_SUSPEND`` and ``CPU_ON`` calls to validate the non-secure ``entry_point`` 2992parameter passed by the normal world. If the ``entry_point`` is invalid, 2993the platform must return PSCI_E_INVALID_ADDRESS as error, which is 2994propagated back to the normal world PSCI client. 2995 2996plat_psci_ops.get_sys_suspend_power_state() 2997........................................... 2998 2999This function is called by the PSCI implementation during the ``SYSTEM_SUSPEND`` 3000call to get the ``req_state`` parameter from platform which encodes the power 3001domain level specific local states to suspend to system affinity level. The 3002``req_state`` will be utilized to do the PSCI state coordination and 3003``pwr_domain_suspend()`` will be invoked with the coordinated target state to 3004enter system suspend. 3005 3006plat_psci_ops.get_pwr_lvl_state_idx() 3007..................................... 3008 3009This is an optional function and, if implemented, is invoked by the PSCI 3010implementation to convert the ``local_state`` (first argument) at a specified 3011``pwr_lvl`` (second argument) to an index between 0 and 3012``PLAT_MAX_PWR_LVL_STATES`` - 1. This function is only needed if the platform 3013supports more than two local power states at each power domain level, that is 3014``PLAT_MAX_PWR_LVL_STATES`` is greater than 2, and needs to account for these 3015local power states. 3016 3017plat_psci_ops.translate_power_state_by_mpidr() 3018.............................................. 3019 3020This is an optional function and, if implemented, verifies the ``power_state`` 3021(second argument) parameter of the PSCI API corresponding to a target power 3022domain. The target power domain is identified by using both ``MPIDR`` (first 3023argument) and the power domain level encoded in ``power_state``. The power domain 3024level specific local states are to be extracted from ``power_state`` and be 3025populated in the ``output_state`` (third argument) array. The functionality 3026is similar to the ``validate_power_state`` function described above and is 3027envisaged to be used in case the validity of ``power_state`` depend on the 3028targeted power domain. If the ``power_state`` is invalid for the targeted power 3029domain, the platform must return PSCI_E_INVALID_PARAMS as error. If this 3030function is not implemented, then the generic implementation relies on 3031``validate_power_state`` function to translate the ``power_state``. 3032 3033This function can also be used in case the platform wants to support local 3034power state encoding for ``power_state`` parameter of PSCI_STAT_COUNT/RESIDENCY 3035APIs as described in Section 5.18 of `PSCI`_. 3036 3037plat_psci_ops.get_node_hw_state() 3038................................. 3039 3040This is an optional function. If implemented this function is intended to return 3041the power state of a node (identified by the first parameter, the ``MPIDR``) in 3042the power domain topology (identified by the second parameter, ``power_level``), 3043as retrieved from a power controller or equivalent component on the platform. 3044Upon successful completion, the implementation must map and return the final 3045status among ``HW_ON``, ``HW_OFF`` or ``HW_STANDBY``. Upon encountering failures, it 3046must return either ``PSCI_E_INVALID_PARAMS`` or ``PSCI_E_NOT_SUPPORTED`` as 3047appropriate. 3048 3049Implementations are not expected to handle ``power_levels`` greater than 3050``PLAT_MAX_PWR_LVL``. 3051 3052plat_psci_ops.system_reset2() 3053............................. 3054 3055This is an optional function. If implemented this function is 3056called during the ``SYSTEM_RESET2`` call to perform a reset 3057based on the first parameter ``reset_type`` as specified in 3058`PSCI`_. The parameter ``cookie`` can be used to pass additional 3059reset information. If the ``reset_type`` is not supported, the 3060function must return ``PSCI_E_NOT_SUPPORTED``. For architectural 3061resets, all failures must return ``PSCI_E_INVALID_PARAMETERS`` 3062and vendor reset can return other PSCI error codes as defined 3063in `PSCI`_. On success this function will not return. 3064 3065plat_psci_ops.write_mem_protect() 3066................................. 3067 3068This is an optional function. If implemented it enables or disables the 3069``MEM_PROTECT`` functionality based on the value of ``val``. 3070A non-zero value enables ``MEM_PROTECT`` and a value of zero 3071disables it. Upon encountering failures it must return a negative value 3072and on success it must return 0. 3073 3074plat_psci_ops.read_mem_protect() 3075................................ 3076 3077This is an optional function. If implemented it returns the current 3078state of ``MEM_PROTECT`` via the ``val`` parameter. Upon encountering 3079failures it must return a negative value and on success it must 3080return 0. 3081 3082plat_psci_ops.mem_protect_chk() 3083............................... 3084 3085This is an optional function. If implemented it checks if a memory 3086region defined by a base address ``base`` and with a size of ``length`` 3087bytes is protected by ``MEM_PROTECT``. If the region is protected 3088then it must return 0, otherwise it must return a negative number. 3089 3090.. _porting_guide_imf_in_bl31: 3091 3092Interrupt Management framework (in BL31) 3093---------------------------------------- 3094 3095BL31 implements an Interrupt Management Framework (IMF) to manage interrupts 3096generated in either security state and targeted to EL1 or EL2 in the non-secure 3097state or EL3/S-EL1 in the secure state. The design of this framework is 3098described in the :ref:`Interrupt Management Framework` 3099 3100A platform should export the following APIs to support the IMF. The following 3101text briefly describes each API and its implementation in Arm standard 3102platforms. The API implementation depends upon the type of interrupt controller 3103present in the platform. Arm standard platform layer supports both 3104`Arm Generic Interrupt Controller version 2.0 (GICv2)`_ 3105and `3.0 (GICv3)`_. Juno builds the Arm platform layer to use GICv2 and the 3106FVP can be configured to use either GICv2 or GICv3 depending on the build flag 3107``FVP_USE_GIC_DRIVER`` (See :ref:`build_options_arm_fvp_platform` for more 3108details). 3109 3110See also: :ref:`Interrupt Controller Abstraction APIs<Platform Interrupt Controller API>`. 3111 3112Function : plat_interrupt_type_to_line() [mandatory] 3113~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3114 3115:: 3116 3117 Argument : uint32_t, uint32_t 3118 Return : uint32_t 3119 3120The Arm processor signals an interrupt exception either through the IRQ or FIQ 3121interrupt line. The specific line that is signaled depends on how the interrupt 3122controller (IC) reports different interrupt types from an execution context in 3123either security state. The IMF uses this API to determine which interrupt line 3124the platform IC uses to signal each type of interrupt supported by the framework 3125from a given security state. This API must be invoked at EL3. 3126 3127The first parameter will be one of the ``INTR_TYPE_*`` values (see 3128:ref:`Interrupt Management Framework`) indicating the target type of the 3129interrupt, the second parameter is the security state of the originating 3130execution context. The return result is the bit position in the ``SCR_EL3`` 3131register of the respective interrupt trap: IRQ=1, FIQ=2. 3132 3133In the case of Arm standard platforms using GICv2, S-EL1 interrupts are 3134configured as FIQs and Non-secure interrupts as IRQs from either security 3135state. 3136 3137In the case of Arm standard platforms using GICv3, the interrupt line to be 3138configured depends on the security state of the execution context when the 3139interrupt is signalled and are as follows: 3140 3141- The S-EL1 interrupts are signaled as IRQ in S-EL0/1 context and as FIQ in 3142 NS-EL0/1/2 context. 3143- The Non secure interrupts are signaled as FIQ in S-EL0/1 context and as IRQ 3144 in the NS-EL0/1/2 context. 3145- The EL3 interrupts are signaled as FIQ in both S-EL0/1 and NS-EL0/1/2 3146 context. 3147 3148Function : plat_ic_get_pending_interrupt_type() [mandatory] 3149~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3150 3151:: 3152 3153 Argument : void 3154 Return : uint32_t 3155 3156This API returns the type of the highest priority pending interrupt at the 3157platform IC. The IMF uses the interrupt type to retrieve the corresponding 3158handler function. ``INTR_TYPE_INVAL`` is returned when there is no interrupt 3159pending. The valid interrupt types that can be returned are ``INTR_TYPE_EL3``, 3160``INTR_TYPE_S_EL1`` and ``INTR_TYPE_NS``. This API must be invoked at EL3. 3161 3162In the case of Arm standard platforms using GICv2, the *Highest Priority 3163Pending Interrupt Register* (``GICC_HPPIR``) is read to determine the id of 3164the pending interrupt. The type of interrupt depends upon the id value as 3165follows. 3166 3167#. id < 1022 is reported as a S-EL1 interrupt 3168#. id = 1022 is reported as a Non-secure interrupt. 3169#. id = 1023 is reported as an invalid interrupt type. 3170 3171In the case of Arm standard platforms using GICv3, the system register 3172``ICC_HPPIR0_EL1``, *Highest Priority Pending group 0 Interrupt Register*, 3173is read to determine the id of the pending interrupt. The type of interrupt 3174depends upon the id value as follows. 3175 3176#. id = ``PENDING_G1S_INTID`` (1020) is reported as a S-EL1 interrupt 3177#. id = ``PENDING_G1NS_INTID`` (1021) is reported as a Non-secure interrupt. 3178#. id = ``GIC_SPURIOUS_INTERRUPT`` (1023) is reported as an invalid interrupt type. 3179#. All other interrupt id's are reported as EL3 interrupt. 3180 3181Function : plat_ic_get_pending_interrupt_id() [mandatory] 3182~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3183 3184:: 3185 3186 Argument : void 3187 Return : uint32_t 3188 3189This API returns the id of the highest priority pending interrupt at the 3190platform IC. ``INTR_ID_UNAVAILABLE`` is returned when there is no interrupt 3191pending. 3192 3193In the case of Arm standard platforms using GICv2, the *Highest Priority 3194Pending Interrupt Register* (``GICC_HPPIR``) is read to determine the id of the 3195pending interrupt. The id that is returned by API depends upon the value of 3196the id read from the interrupt controller as follows. 3197 3198#. id < 1022. id is returned as is. 3199#. id = 1022. The *Aliased Highest Priority Pending Interrupt Register* 3200 (``GICC_AHPPIR``) is read to determine the id of the non-secure interrupt. 3201 This id is returned by the API. 3202#. id = 1023. ``INTR_ID_UNAVAILABLE`` is returned. 3203 3204In the case of Arm standard platforms using GICv3, if the API is invoked from 3205EL3, the system register ``ICC_HPPIR0_EL1``, *Highest Priority Pending Interrupt 3206group 0 Register*, is read to determine the id of the pending interrupt. The id 3207that is returned by API depends upon the value of the id read from the 3208interrupt controller as follows. 3209 3210#. id < ``PENDING_G1S_INTID`` (1020). id is returned as is. 3211#. id = ``PENDING_G1S_INTID`` (1020) or ``PENDING_G1NS_INTID`` (1021). The system 3212 register ``ICC_HPPIR1_EL1``, *Highest Priority Pending Interrupt group 1 3213 Register* is read to determine the id of the group 1 interrupt. This id 3214 is returned by the API as long as it is a valid interrupt id 3215#. If the id is any of the special interrupt identifiers, 3216 ``INTR_ID_UNAVAILABLE`` is returned. 3217 3218When the API invoked from S-EL1 for GICv3 systems, the id read from system 3219register ``ICC_HPPIR1_EL1``, *Highest Priority Pending group 1 Interrupt 3220Register*, is returned if is not equal to GIC_SPURIOUS_INTERRUPT (1023) else 3221``INTR_ID_UNAVAILABLE`` is returned. 3222 3223Function : plat_ic_acknowledge_interrupt() [mandatory] 3224~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3225 3226:: 3227 3228 Argument : void 3229 Return : uint32_t 3230 3231This API is used by the CPU to indicate to the platform IC that processing of 3232the highest pending interrupt has begun. It should return the raw, unmodified 3233value obtained from the interrupt controller when acknowledging an interrupt. 3234The actual interrupt number shall be extracted from this raw value using the API 3235`plat_ic_get_interrupt_id()<plat_ic_get_interrupt_id>`. 3236 3237This function in Arm standard platforms using GICv2, reads the *Interrupt 3238Acknowledge Register* (``GICC_IAR``). This changes the state of the highest 3239priority pending interrupt from pending to active in the interrupt controller. 3240It returns the value read from the ``GICC_IAR``, unmodified. 3241 3242In the case of Arm standard platforms using GICv3, if the API is invoked 3243from EL3, the function reads the system register ``ICC_IAR0_EL1``, *Interrupt 3244Acknowledge Register group 0*. If the API is invoked from S-EL1, the function 3245reads the system register ``ICC_IAR1_EL1``, *Interrupt Acknowledge Register 3246group 1*. The read changes the state of the highest pending interrupt from 3247pending to active in the interrupt controller. The value read is returned 3248unmodified. 3249 3250The TSP uses this API to start processing of the secure physical timer 3251interrupt. 3252 3253Function : plat_ic_end_of_interrupt() [mandatory] 3254~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3255 3256:: 3257 3258 Argument : uint32_t 3259 Return : void 3260 3261This API is used by the CPU to indicate to the platform IC that processing of 3262the interrupt corresponding to the id (passed as the parameter) has 3263finished. The id should be the same as the id returned by the 3264``plat_ic_acknowledge_interrupt()`` API. 3265 3266Arm standard platforms write the id to the *End of Interrupt Register* 3267(``GICC_EOIR``) in case of GICv2, and to ``ICC_EOIR0_EL1`` or ``ICC_EOIR1_EL1`` 3268system register in case of GICv3 depending on where the API is invoked from, 3269EL3 or S-EL1. This deactivates the corresponding interrupt in the interrupt 3270controller. 3271 3272The TSP uses this API to finish processing of the secure physical timer 3273interrupt. 3274 3275Function : plat_ic_get_interrupt_type() [mandatory] 3276~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3277 3278:: 3279 3280 Argument : uint32_t 3281 Return : uint32_t 3282 3283This API returns the type of the interrupt id passed as the parameter. 3284``INTR_TYPE_INVAL`` is returned if the id is invalid. If the id is valid, a valid 3285interrupt type (one of ``INTR_TYPE_EL3``, ``INTR_TYPE_S_EL1`` and ``INTR_TYPE_NS``) is 3286returned depending upon how the interrupt has been configured by the platform 3287IC. This API must be invoked at EL3. 3288 3289Arm standard platforms using GICv2 configures S-EL1 interrupts as Group0 interrupts 3290and Non-secure interrupts as Group1 interrupts. It reads the group value 3291corresponding to the interrupt id from the relevant *Interrupt Group Register* 3292(``GICD_IGROUPRn``). It uses the group value to determine the type of interrupt. 3293 3294In the case of Arm standard platforms using GICv3, both the *Interrupt Group 3295Register* (``GICD_IGROUPRn``) and *Interrupt Group Modifier Register* 3296(``GICD_IGRPMODRn``) is read to figure out whether the interrupt is configured 3297as Group 0 secure interrupt, Group 1 secure interrupt or Group 1 NS interrupt. 3298 3299Common helper functions 3300----------------------- 3301Function : elx_panic() 3302~~~~~~~~~~~~~~~~~~~~~~ 3303 3304:: 3305 3306 Argument : void 3307 Return : void 3308 3309This API is called from assembly files when reporting a critical failure 3310that has occured in lower EL and is been trapped in EL3. This call 3311**must not** return. 3312 3313Function : el3_panic() 3314~~~~~~~~~~~~~~~~~~~~~~ 3315 3316:: 3317 3318 Argument : void 3319 Return : void 3320 3321This API is called from assembly files when encountering a critical failure that 3322cannot be recovered from. This function assumes that it is invoked from a C 3323runtime environment i.e. valid stack exists. This call **must not** return. 3324 3325Function : panic() 3326~~~~~~~~~~~~~~~~~~ 3327 3328:: 3329 3330 Argument : void 3331 Return : void 3332 3333This API called from C files when encountering a critical failure that cannot 3334be recovered from. This function in turn prints backtrace (if enabled) and calls 3335el3_panic(). This call **must not** return. 3336 3337Crash Reporting mechanism (in BL31) 3338----------------------------------- 3339 3340BL31 implements a crash reporting mechanism which prints the various registers 3341of the CPU to enable quick crash analysis and debugging. This mechanism relies 3342on the platform implementing ``plat_crash_console_init``, 3343``plat_crash_console_putc`` and ``plat_crash_console_flush``. 3344 3345The file ``plat/common/aarch64/crash_console_helpers.S`` contains sample 3346implementation of all of them. Platforms may include this file to their 3347makefiles in order to benefit from them. By default, they will cause the crash 3348output to be routed over the normal console infrastructure and get printed on 3349consoles configured to output in crash state. ``console_set_scope()`` can be 3350used to control whether a console is used for crash output. 3351 3352.. note:: 3353 Platforms are responsible for making sure that they only mark consoles for 3354 use in the crash scope that are able to support this, i.e. that are written 3355 in assembly and conform with the register clobber rules for putc() 3356 (x0-x2, x16-x17) and flush() (x0-x3, x16-x17) crash callbacks. 3357 3358In some cases (such as debugging very early crashes that happen before the 3359normal boot console can be set up), platforms may want to control crash output 3360more explicitly. These platforms may instead provide custom implementations for 3361these. They are executed outside of a C environment and without a stack. Many 3362console drivers provide functions named ``console_xxx_core_init/putc/flush`` 3363that are designed to be used by these functions. See Arm platforms (like juno) 3364for an example of this. 3365 3366Function : plat_crash_console_init [mandatory] 3367~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3368 3369:: 3370 3371 Argument : void 3372 Return : int 3373 3374This API is used by the crash reporting mechanism to initialize the crash 3375console. It must only use the general purpose registers x0 through x7 to do the 3376initialization and returns 1 on success. 3377 3378Function : plat_crash_console_putc [mandatory] 3379~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3380 3381:: 3382 3383 Argument : int 3384 Return : int 3385 3386This API is used by the crash reporting mechanism to print a character on the 3387designated crash console. It must only use general purpose registers x1 and 3388x2 to do its work. The parameter and the return value are in general purpose 3389register x0. 3390 3391Function : plat_crash_console_flush [mandatory] 3392~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3393 3394:: 3395 3396 Argument : void 3397 Return : void 3398 3399This API is used by the crash reporting mechanism to force write of all buffered 3400data on the designated crash console. It should only use general purpose 3401registers x0 through x5 to do its work. 3402 3403Function : plat_setup_early_console [optional] 3404~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3405 3406:: 3407 3408 Argument : void 3409 Return : void 3410 3411This API is used to setup the early console, it is required only if the flag 3412``EARLY_CONSOLE`` is enabled. 3413 3414.. _External Abort handling and RAS Support: 3415 3416External Abort handling and RAS Support 3417--------------------------------------- 3418 3419Function : plat_ea_handler 3420~~~~~~~~~~~~~~~~~~~~~~~~~~ 3421 3422:: 3423 3424 Argument : int 3425 Argument : uint64_t 3426 Argument : void * 3427 Argument : void * 3428 Argument : uint64_t 3429 Return : void 3430 3431This function is invoked by the runtime exception handling framework for the 3432platform to handle an External Abort received at EL3. The intention of the 3433function is to attempt to resolve the cause of External Abort and return; 3434if that's not possible then an orderly shutdown of the system is initiated. 3435 3436The first parameter (``int ea_reason``) indicates the reason for External Abort. 3437Its value is one of ``ERROR_EA_*`` constants defined in ``ea_handle.h``. 3438 3439The second parameter (``uint64_t syndrome``) is the respective syndrome 3440presented to EL3 after having received the External Abort. Depending on the 3441nature of the abort (as can be inferred from the ``ea_reason`` parameter), this 3442can be the content of either ``ESR_EL3`` or ``DISR_EL1``. 3443 3444The third parameter (``void *cookie``) is unused for now. The fourth parameter 3445(``void *handle``) is a pointer to the preempted context. The fifth parameter 3446(``uint64_t flags``) indicates the preempted security state. These parameters 3447are received from the top-level exception handler. 3448 3449This function must be implemented if a platform expects Firmware First handling 3450of External Aborts. 3451 3452Function : plat_handle_uncontainable_ea 3453~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3454 3455:: 3456 3457 Argument : int 3458 Argument : uint64_t 3459 Return : void 3460 3461This function is invoked by the RAS framework when an External Abort of 3462Uncontainable type is received at EL3. Due to the critical nature of 3463Uncontainable errors, the intention of this function is to initiate orderly 3464shutdown of the system, and is not expected to return. 3465 3466This function must be implemented in assembly. 3467 3468The first and second parameters are the same as that of ``plat_ea_handler``. 3469 3470The default implementation of this function calls 3471``report_unhandled_exception``. 3472 3473Function : plat_handle_double_fault 3474~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3475 3476:: 3477 3478 Argument : int 3479 Argument : uint64_t 3480 Return : void 3481 3482This function is invoked by the RAS framework when another External Abort is 3483received at EL3 while one is already being handled. I.e., a call to 3484``plat_ea_handler`` is outstanding. Due to its critical nature, the intention of 3485this function is to initiate orderly shutdown of the system, and is not expected 3486recover or return. 3487 3488This function must be implemented in assembly. 3489 3490The first and second parameters are the same as that of ``plat_ea_handler``. 3491 3492The default implementation of this function calls 3493``report_unhandled_exception``. 3494 3495Function : plat_handle_el3_ea 3496~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3497 3498:: 3499 3500 Return : void 3501 3502This function is invoked when an External Abort is received while executing in 3503EL3. Due to its critical nature, the intention of this function is to initiate 3504orderly shutdown of the system, and is not expected recover or return. 3505 3506This function must be implemented in assembly. 3507 3508The default implementation of this function calls 3509``report_unhandled_exception``. 3510 3511Function : plat_handle_rng_trap 3512~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3513 3514:: 3515 3516 Argument : uint64_t 3517 Argument : cpu_context_t * 3518 Return : int 3519 3520This function is invoked by BL31's exception handler when there is a synchronous 3521system register trap caused by access to the RNDR or RNDRRS registers. It allows 3522platforms implementing ``FEAT_RNG_TRAP`` and enabling ``ENABLE_FEAT_RNG_TRAP`` to 3523emulate those system registers by returing back some entropy to the lower EL. 3524 3525The first parameter (``uint64_t esr_el3``) contains the content of the ESR_EL3 3526syndrome register, which encodes the instruction that was trapped. The interesting 3527information in there is the target register (``get_sysreg_iss_rt()``). 3528 3529The second parameter (``cpu_context_t *ctx``) represents the CPU state in the 3530lower exception level, at the time when the execution of the ``mrs`` instruction 3531was trapped. Its content can be changed, to put the entropy into the target 3532register. 3533 3534The return value indicates how to proceed: 3535 3536- When returning ``TRAP_RET_UNHANDLED`` (-1), the machine will panic. 3537- When returning ``TRAP_RET_REPEAT`` (0), the exception handler will return 3538 to the same instruction, so its execution will be repeated. 3539- When returning ``TRAP_RET_CONTINUE`` (1), the exception handler will return 3540 to the next instruction. 3541 3542This function needs to be implemented by a platform if it enables FEAT_RNG_TRAP. 3543 3544Function : plat_handle_impdef_trap 3545~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3546 3547:: 3548 3549 Argument : uint64_t 3550 Argument : cpu_context_t * 3551 Return : int 3552 3553This function is invoked by BL31's exception handler when there is a synchronous 3554system register trap caused by access to the implementation defined registers. 3555It allows platforms enabling ``IMPDEF_SYSREG_TRAP`` to emulate those system 3556registers choosing to program bits of their choice. 3557 3558The first parameter (``uint64_t esr_el3``) contains the content of the ESR_EL3 3559syndrome register, which encodes the instruction that was trapped. 3560 3561The second parameter (``cpu_context_t *ctx``) represents the CPU state in the 3562lower exception level, at the time when the execution of the ``mrs`` instruction 3563was trapped. 3564 3565The return value indicates how to proceed: 3566 3567- When returning ``TRAP_RET_UNHANDLED`` (-1), the machine will panic. 3568- When returning ``TRAP_RET_REPEAT`` (0), the exception handler will return 3569 to the same instruction, so its execution will be repeated. 3570- When returning ``TRAP_RET_CONTINUE`` (1), the exception handler will return 3571 to the next instruction. 3572 3573This function needs to be implemented by a platform if it enables 3574IMPDEF_SYSREG_TRAP. 3575 3576Build flags 3577----------- 3578 3579There are some build flags which can be defined by the platform to control 3580inclusion or exclusion of certain BL stages from the FIP image. These flags 3581need to be defined in the platform makefile which will get included by the 3582build system. 3583 3584- **NEED_BL33** 3585 By default, this flag is defined ``yes`` by the build system and ``BL33`` 3586 build option should be supplied as a build option. The platform has the 3587 option of excluding the BL33 image in the ``fip`` image by defining this flag 3588 to ``no``. If any of the options ``EL3_PAYLOAD_BASE`` or ``PRELOADED_BL33_BASE`` 3589 are used, this flag will be set to ``no`` automatically. 3590 3591- **ARM_ARCH_MAJOR and ARM_ARCH_MINOR** 3592 By default, ARM_ARCH_MAJOR.ARM_ARCH_MINOR is set to 8.0 in ``defaults.mk``, 3593 if the platform makefile/build defines or uses the correct ARM_ARCH_MAJOR and 3594 ARM_ARCH_MINOR then mandatory Architectural features available for that Arch 3595 version will be enabled by default and any optional Arch feature supported by 3596 the Architecture and available in TF-A can be enabled from platform specific 3597 makefile. Look up to ``arch_features.mk`` for details pertaining to mandatory 3598 and optional Arch specific features. 3599 3600Platform include paths 3601---------------------- 3602 3603Platforms are allowed to add more include paths to be passed to the compiler. 3604The ``PLAT_INCLUDES`` variable is used for this purpose. This is needed in 3605particular for the file ``platform_def.h``. 3606 3607Example: 3608 3609.. code:: c 3610 3611 PLAT_INCLUDES += -Iinclude/plat/myplat/include 3612 3613C Library 3614--------- 3615 3616To avoid subtle toolchain behavioral dependencies, the header files provided 3617by the compiler are not used. The software is built with the ``-nostdinc`` flag 3618to ensure no headers are included from the toolchain inadvertently. Instead the 3619required headers are included in the TF-A source tree. The library only 3620contains those C library definitions required by the local implementation. If 3621more functionality is required, the needed library functions will need to be 3622added to the local implementation. 3623 3624Some C headers have been obtained from `FreeBSD`_ and `SCC`_, while others have 3625been written specifically for TF-A. Some implementation files have been obtained 3626from `FreeBSD`_, others have been written specifically for TF-A as well. The 3627files can be found in ``include/lib/libc`` and ``lib/libc``. 3628 3629SCC can be found in http://www.simple-cc.org/. A copy of the `FreeBSD`_ sources 3630can be obtained from http://github.com/freebsd/freebsd. 3631 3632Storage abstraction layer 3633------------------------- 3634 3635In order to improve platform independence and portability a storage abstraction 3636layer is used to load data from non-volatile platform storage. Currently 3637storage access is only required by BL1 and BL2 phases and performed inside the 3638``load_image()`` function in ``bl_common.c``. 3639 3640.. uml:: resources/diagrams/plantuml/io_framework_usage_overview.puml 3641 3642It is mandatory to implement at least one storage driver. For the Arm 3643development platforms the Firmware Image Package (FIP) driver is provided as 3644the default means to load data from storage (see :ref:`firmware_design_fip`). 3645The storage layer is described in the header file 3646``include/drivers/io/io_storage.h``. The implementation of the common library is 3647in ``drivers/io/io_storage.c`` and the driver files are located in 3648``drivers/io/``. 3649 3650.. uml:: resources/diagrams/plantuml/io_arm_class_diagram.puml 3651 3652Each IO driver must provide ``io_dev_*`` structures, as described in 3653``drivers/io/io_driver.h``. These are returned via a mandatory registration 3654function that is called on platform initialization. The semi-hosting driver 3655implementation in ``io_semihosting.c`` can be used as an example. 3656 3657Each platform should register devices and their drivers via the storage 3658abstraction layer. These drivers then need to be initialized by bootloader 3659phases as required in their respective ``blx_platform_setup()`` functions. 3660 3661.. uml:: resources/diagrams/plantuml/io_dev_registration.puml 3662 3663The storage abstraction layer provides mechanisms (``io_dev_init()``) to 3664initialize storage devices before IO operations are called. 3665 3666.. uml:: resources/diagrams/plantuml/io_dev_init_and_check.puml 3667 3668The basic operations supported by the layer 3669include ``open()``, ``close()``, ``read()``, ``write()``, ``size()`` and ``seek()``. 3670Drivers do not have to implement all operations, but each platform must 3671provide at least one driver for a device capable of supporting generic 3672operations such as loading a bootloader image. 3673 3674The current implementation only allows for known images to be loaded by the 3675firmware. These images are specified by using their identifiers, as defined in 3676``include/plat/common/common_def.h`` (or a separate header file included from 3677there). The platform layer (``plat_get_image_source()``) then returns a reference 3678to a device and a driver-specific ``spec`` which will be understood by the driver 3679to allow access to the image data. 3680 3681The layer is designed in such a way that is it possible to chain drivers with 3682other drivers. For example, file-system drivers may be implemented on top of 3683physical block devices, both represented by IO devices with corresponding 3684drivers. In such a case, the file-system "binding" with the block device may 3685be deferred until the file-system device is initialised. 3686 3687The abstraction currently depends on structures being statically allocated 3688by the drivers and callers, as the system does not yet provide a means of 3689dynamically allocating memory. This may also have the affect of limiting the 3690amount of open resources per driver. 3691 3692Measured Boot Platform Interface 3693-------------------------------- 3694 3695Enabling the MEASURED_BOOT flag adds extra platform requirements. Please refer 3696to :ref:`Measured Boot Design` for more details. 3697 3698-------------- 3699 3700*Copyright (c) 2013-2024, Arm Limited and Contributors. All rights reserved.* 3701 3702.. _PSCI: https://developer.arm.com/documentation/den0022/latest/ 3703.. _Arm Generic Interrupt Controller version 2.0 (GICv2): http://infocenter.arm.com/help/topic/com.arm.doc.ihi0048b/index.html 3704.. _3.0 (GICv3): http://infocenter.arm.com/help/topic/com.arm.doc.ihi0069b/index.html 3705.. _FreeBSD: https://www.freebsd.org 3706.. _SCC: http://www.simple-cc.org/ 3707.. _DRTM: https://developer.arm.com/documentation/den0113/a 3708