1ARM Trusted Firmware Porting Guide 2================================== 3 4 5.. section-numbering:: 6 :suffix: . 7 8.. contents:: 9 10-------------- 11 12Introduction 13------------ 14 15Please note that this document has been updated for the new platform API 16as required by the PSCI v1.0 implementation. Please refer to the 17`Migration Guide`_ for the previous platform API. 18 19Porting the ARM Trusted Firmware to a new platform involves making some 20mandatory and optional modifications for both the cold and warm boot paths. 21Modifications consist of: 22 23- Implementing a platform-specific function or variable, 24- Setting up the execution context in a certain way, or 25- Defining certain constants (for example #defines). 26 27The platform-specific functions and variables are declared in 28`include/plat/common/platform.h`_. The firmware provides a default implementation 29of variables and functions to fulfill the optional requirements. These 30implementations are all weakly defined; they are provided to ease the porting 31effort. Each platform port can override them with its own implementation if the 32default implementation is inadequate. 33 34Platform ports that want to be aligned with standard ARM platforms (for example 35FVP and Juno) may also use `include/plat/arm/common/plat\_arm.h`_ and the 36corresponding source files in ``plat/arm/common/``. These provide standard 37implementations for some of the required platform porting functions. However, 38using these functions requires the platform port to implement additional 39ARM standard platform porting functions. These additional functions are not 40documented here. 41 42Some modifications are common to all Boot Loader (BL) stages. Section 2 43discusses these in detail. The subsequent sections discuss the remaining 44modifications for each BL stage in detail. 45 46This document should be read in conjunction with the ARM Trusted Firmware 47`User Guide`_. 48 49Common modifications 50-------------------- 51 52This section covers the modifications that should be made by the platform for 53each BL stage to correctly port the firmware stack. They are categorized as 54either mandatory or optional. 55 56Common mandatory modifications 57------------------------------ 58 59A platform port must enable the Memory Management Unit (MMU) as well as the 60instruction and data caches for each BL stage. Setting up the translation 61tables is the responsibility of the platform port because memory maps differ 62across platforms. A memory translation library (see ``lib/xlat_tables/``) is 63provided to help in this setup. 64 65Note that although this library supports non-identity mappings, this is intended 66only for re-mapping peripheral physical addresses and allows platforms with high 67I/O addresses to reduce their virtual address space. All other addresses 68corresponding to code and data must currently use an identity mapping. 69 70Also, the only translation granule size supported in Trusted Firmware is 4KB, as 71various parts of the code assume that is the case. It is not possible to switch 72to 16 KB or 64 KB granule sizes at the moment. 73 74In ARM standard platforms, each BL stage configures the MMU in the 75platform-specific architecture setup function, ``blX_plat_arch_setup()``, and uses 76an identity mapping for all addresses. 77 78If the build option ``USE_COHERENT_MEM`` is enabled, each platform can allocate a 79block of identity mapped secure memory with Device-nGnRE attributes aligned to 80page boundary (4K) for each BL stage. All sections which allocate coherent 81memory are grouped under ``coherent_ram``. For ex: Bakery locks are placed in a 82section identified by name ``bakery_lock`` inside ``coherent_ram`` so that its 83possible for the firmware to place variables in it using the following C code 84directive: 85 86:: 87 88 __section("bakery_lock") 89 90Or alternatively the following assembler code directive: 91 92:: 93 94 .section bakery_lock 95 96The ``coherent_ram`` section is a sum of all sections like ``bakery_lock`` which are 97used to allocate any data structures that are accessed both when a CPU is 98executing with its MMU and caches enabled, and when it's running with its MMU 99and caches disabled. Examples are given below. 100 101The following variables, functions and constants must be defined by the platform 102for the firmware to work correctly. 103 104File : platform\_def.h [mandatory] 105~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 106 107Each platform must ensure that a header file of this name is in the system 108include path with the following constants defined. This may require updating the 109list of ``PLAT_INCLUDES`` in the ``platform.mk`` file. In the ARM development 110platforms, this file is found in ``plat/arm/board/<plat_name>/include/``. 111 112Platform ports may optionally use the file `include/plat/common/common\_def.h`_, 113which provides typical values for some of the constants below. These values are 114likely to be suitable for all platform ports. 115 116Platform ports that want to be aligned with standard ARM platforms (for example 117FVP and Juno) may also use `include/plat/arm/common/arm\_def.h`_, which provides 118standard values for some of the constants below. However, this requires the 119platform port to define additional platform porting constants in 120``platform_def.h``. These additional constants are not documented here. 121 122- **#define : PLATFORM\_LINKER\_FORMAT** 123 124 Defines the linker format used by the platform, for example 125 ``elf64-littleaarch64``. 126 127- **#define : PLATFORM\_LINKER\_ARCH** 128 129 Defines the processor architecture for the linker by the platform, for 130 example ``aarch64``. 131 132- **#define : PLATFORM\_STACK\_SIZE** 133 134 Defines the normal stack memory available to each CPU. This constant is used 135 by `plat/common/aarch64/platform\_mp\_stack.S`_ and 136 `plat/common/aarch64/platform\_up\_stack.S`_. 137 138- **define : CACHE\_WRITEBACK\_GRANULE** 139 140 Defines the size in bits of the largest cache line across all the cache 141 levels in the platform. 142 143- **#define : FIRMWARE\_WELCOME\_STR** 144 145 Defines the character string printed by BL1 upon entry into the ``bl1_main()`` 146 function. 147 148- **#define : PLATFORM\_CORE\_COUNT** 149 150 Defines the total number of CPUs implemented by the platform across all 151 clusters in the system. 152 153- **#define : PLAT\_NUM\_PWR\_DOMAINS** 154 155 Defines the total number of nodes in the power domain topology 156 tree at all the power domain levels used by the platform. 157 This macro is used by the PSCI implementation to allocate 158 data structures to represent power domain topology. 159 160- **#define : PLAT\_MAX\_PWR\_LVL** 161 162 Defines the maximum power domain level that the power management operations 163 should apply to. More often, but not always, the power domain level 164 corresponds to affinity level. This macro allows the PSCI implementation 165 to know the highest power domain level that it should consider for power 166 management operations in the system that the platform implements. For 167 example, the Base AEM FVP implements two clusters with a configurable 168 number of CPUs and it reports the maximum power domain level as 1. 169 170- **#define : PLAT\_MAX\_OFF\_STATE** 171 172 Defines the local power state corresponding to the deepest power down 173 possible at every power domain level in the platform. The local power 174 states for each level may be sparsely allocated between 0 and this value 175 with 0 being reserved for the RUN state. The PSCI implementation uses this 176 value to initialize the local power states of the power domain nodes and 177 to specify the requested power state for a PSCI\_CPU\_OFF call. 178 179- **#define : PLAT\_MAX\_RET\_STATE** 180 181 Defines the local power state corresponding to the deepest retention state 182 possible at every power domain level in the platform. This macro should be 183 a value less than PLAT\_MAX\_OFF\_STATE and greater than 0. It is used by the 184 PSCI implementation to distinguish between retention and power down local 185 power states within PSCI\_CPU\_SUSPEND call. 186 187- **#define : PLAT\_MAX\_PWR\_LVL\_STATES** 188 189 Defines the maximum number of local power states per power domain level 190 that the platform supports. The default value of this macro is 2 since 191 most platforms just support a maximum of two local power states at each 192 power domain level (power-down and retention). If the platform needs to 193 account for more local power states, then it must redefine this macro. 194 195 Currently, this macro is used by the Generic PSCI implementation to size 196 the array used for PSCI\_STAT\_COUNT/RESIDENCY accounting. 197 198- **#define : BL1\_RO\_BASE** 199 200 Defines the base address in secure ROM where BL1 originally lives. Must be 201 aligned on a page-size boundary. 202 203- **#define : BL1\_RO\_LIMIT** 204 205 Defines the maximum address in secure ROM that BL1's actual content (i.e. 206 excluding any data section allocated at runtime) can occupy. 207 208- **#define : BL1\_RW\_BASE** 209 210 Defines the base address in secure RAM where BL1's read-write data will live 211 at runtime. Must be aligned on a page-size boundary. 212 213- **#define : BL1\_RW\_LIMIT** 214 215 Defines the maximum address in secure RAM that BL1's read-write data can 216 occupy at runtime. 217 218- **#define : BL2\_BASE** 219 220 Defines the base address in secure RAM where BL1 loads the BL2 binary image. 221 Must be aligned on a page-size boundary. 222 223- **#define : BL2\_LIMIT** 224 225 Defines the maximum address in secure RAM that the BL2 image can occupy. 226 227- **#define : BL31\_BASE** 228 229 Defines the base address in secure RAM where BL2 loads the BL31 binary 230 image. Must be aligned on a page-size boundary. 231 232- **#define : BL31\_LIMIT** 233 234 Defines the maximum address in secure RAM that the BL31 image can occupy. 235 236For every image, the platform must define individual identifiers that will be 237used by BL1 or BL2 to load the corresponding image into memory from non-volatile 238storage. For the sake of performance, integer numbers will be used as 239identifiers. The platform will use those identifiers to return the relevant 240information about the image to be loaded (file handler, load address, 241authentication information, etc.). The following image identifiers are 242mandatory: 243 244- **#define : BL2\_IMAGE\_ID** 245 246 BL2 image identifier, used by BL1 to load BL2. 247 248- **#define : BL31\_IMAGE\_ID** 249 250 BL31 image identifier, used by BL2 to load BL31. 251 252- **#define : BL33\_IMAGE\_ID** 253 254 BL33 image identifier, used by BL2 to load BL33. 255 256If Trusted Board Boot is enabled, the following certificate identifiers must 257also be defined: 258 259- **#define : TRUSTED\_BOOT\_FW\_CERT\_ID** 260 261 BL2 content certificate identifier, used by BL1 to load the BL2 content 262 certificate. 263 264- **#define : TRUSTED\_KEY\_CERT\_ID** 265 266 Trusted key certificate identifier, used by BL2 to load the trusted key 267 certificate. 268 269- **#define : SOC\_FW\_KEY\_CERT\_ID** 270 271 BL31 key certificate identifier, used by BL2 to load the BL31 key 272 certificate. 273 274- **#define : SOC\_FW\_CONTENT\_CERT\_ID** 275 276 BL31 content certificate identifier, used by BL2 to load the BL31 content 277 certificate. 278 279- **#define : NON\_TRUSTED\_FW\_KEY\_CERT\_ID** 280 281 BL33 key certificate identifier, used by BL2 to load the BL33 key 282 certificate. 283 284- **#define : NON\_TRUSTED\_FW\_CONTENT\_CERT\_ID** 285 286 BL33 content certificate identifier, used by BL2 to load the BL33 content 287 certificate. 288 289- **#define : FWU\_CERT\_ID** 290 291 Firmware Update (FWU) certificate identifier, used by NS\_BL1U to load the 292 FWU content certificate. 293 294- **#define : PLAT\_CRYPTOCELL\_BASE** 295 296 This defines the base address of ARM® TrustZone® CryptoCell and must be 297 defined if CryptoCell crypto driver is used for Trusted Board Boot. For 298 capable ARM platforms, this driver is used if ``ARM_CRYPTOCELL_INTEG`` is 299 set. 300 301If the AP Firmware Updater Configuration image, BL2U is used, the following 302must also be defined: 303 304- **#define : BL2U\_BASE** 305 306 Defines the base address in secure memory where BL1 copies the BL2U binary 307 image. Must be aligned on a page-size boundary. 308 309- **#define : BL2U\_LIMIT** 310 311 Defines the maximum address in secure memory that the BL2U image can occupy. 312 313- **#define : BL2U\_IMAGE\_ID** 314 315 BL2U image identifier, used by BL1 to fetch an image descriptor 316 corresponding to BL2U. 317 318If the SCP Firmware Update Configuration Image, SCP\_BL2U is used, the following 319must also be defined: 320 321- **#define : SCP\_BL2U\_IMAGE\_ID** 322 323 SCP\_BL2U image identifier, used by BL1 to fetch an image descriptor 324 corresponding to SCP\_BL2U. 325 NOTE: TF does not provide source code for this image. 326 327If the Non-Secure Firmware Updater ROM, NS\_BL1U is used, the following must 328also be defined: 329 330- **#define : NS\_BL1U\_BASE** 331 332 Defines the base address in non-secure ROM where NS\_BL1U executes. 333 Must be aligned on a page-size boundary. 334 NOTE: TF does not provide source code for this image. 335 336- **#define : NS\_BL1U\_IMAGE\_ID** 337 338 NS\_BL1U image identifier, used by BL1 to fetch an image descriptor 339 corresponding to NS\_BL1U. 340 341If the Non-Secure Firmware Updater, NS\_BL2U is used, the following must also 342be defined: 343 344- **#define : NS\_BL2U\_BASE** 345 346 Defines the base address in non-secure memory where NS\_BL2U executes. 347 Must be aligned on a page-size boundary. 348 NOTE: TF does not provide source code for this image. 349 350- **#define : NS\_BL2U\_IMAGE\_ID** 351 352 NS\_BL2U image identifier, used by BL1 to fetch an image descriptor 353 corresponding to NS\_BL2U. 354 355For the the Firmware update capability of TRUSTED BOARD BOOT, the following 356macros may also be defined: 357 358- **#define : PLAT\_FWU\_MAX\_SIMULTANEOUS\_IMAGES** 359 360 Total number of images that can be loaded simultaneously. If the platform 361 doesn't specify any value, it defaults to 10. 362 363If a SCP\_BL2 image is supported by the platform, the following constants must 364also be defined: 365 366- **#define : SCP\_BL2\_IMAGE\_ID** 367 368 SCP\_BL2 image identifier, used by BL2 to load SCP\_BL2 into secure memory 369 from platform storage before being transfered to the SCP. 370 371- **#define : SCP\_FW\_KEY\_CERT\_ID** 372 373 SCP\_BL2 key certificate identifier, used by BL2 to load the SCP\_BL2 key 374 certificate (mandatory when Trusted Board Boot is enabled). 375 376- **#define : SCP\_FW\_CONTENT\_CERT\_ID** 377 378 SCP\_BL2 content certificate identifier, used by BL2 to load the SCP\_BL2 379 content certificate (mandatory when Trusted Board Boot is enabled). 380 381If a BL32 image is supported by the platform, the following constants must 382also be defined: 383 384- **#define : BL32\_IMAGE\_ID** 385 386 BL32 image identifier, used by BL2 to load BL32. 387 388- **#define : TRUSTED\_OS\_FW\_KEY\_CERT\_ID** 389 390 BL32 key certificate identifier, used by BL2 to load the BL32 key 391 certificate (mandatory when Trusted Board Boot is enabled). 392 393- **#define : TRUSTED\_OS\_FW\_CONTENT\_CERT\_ID** 394 395 BL32 content certificate identifier, used by BL2 to load the BL32 content 396 certificate (mandatory when Trusted Board Boot is enabled). 397 398- **#define : BL32\_BASE** 399 400 Defines the base address in secure memory where BL2 loads the BL32 binary 401 image. Must be aligned on a page-size boundary. 402 403- **#define : BL32\_LIMIT** 404 405 Defines the maximum address that the BL32 image can occupy. 406 407If the Test Secure-EL1 Payload (TSP) instantiation of BL32 is supported by the 408platform, the following constants must also be defined: 409 410- **#define : TSP\_SEC\_MEM\_BASE** 411 412 Defines the base address of the secure memory used by the TSP image on the 413 platform. This must be at the same address or below ``BL32_BASE``. 414 415- **#define : TSP\_SEC\_MEM\_SIZE** 416 417 Defines the size of the secure memory used by the BL32 image on the 418 platform. ``TSP_SEC_MEM_BASE`` and ``TSP_SEC_MEM_SIZE`` must fully accomodate 419 the memory required by the BL32 image, defined by ``BL32_BASE`` and 420 ``BL32_LIMIT``. 421 422- **#define : TSP\_IRQ\_SEC\_PHY\_TIMER** 423 424 Defines the ID of the secure physical generic timer interrupt used by the 425 TSP's interrupt handling code. 426 427If the platform port uses the translation table library code, the following 428constants must also be defined: 429 430- **#define : PLAT\_XLAT\_TABLES\_DYNAMIC** 431 432 Optional flag that can be set per-image to enable the dynamic allocation of 433 regions even when the MMU is enabled. If not defined, only static 434 functionality will be available, if defined and set to 1 it will also 435 include the dynamic functionality. 436 437- **#define : MAX\_XLAT\_TABLES** 438 439 Defines the maximum number of translation tables that are allocated by the 440 translation table library code. To minimize the amount of runtime memory 441 used, choose the smallest value needed to map the required virtual addresses 442 for each BL stage. If ``PLAT_XLAT_TABLES_DYNAMIC`` flag is enabled for a BL 443 image, ``MAX_XLAT_TABLES`` must be defined to accommodate the dynamic regions 444 as well. 445 446- **#define : MAX\_MMAP\_REGIONS** 447 448 Defines the maximum number of regions that are allocated by the translation 449 table library code. A region consists of physical base address, virtual base 450 address, size and attributes (Device/Memory, RO/RW, Secure/Non-Secure), as 451 defined in the ``mmap_region_t`` structure. The platform defines the regions 452 that should be mapped. Then, the translation table library will create the 453 corresponding tables and descriptors at runtime. To minimize the amount of 454 runtime memory used, choose the smallest value needed to register the 455 required regions for each BL stage. If ``PLAT_XLAT_TABLES_DYNAMIC`` flag is 456 enabled for a BL image, ``MAX_MMAP_REGIONS`` must be defined to accommodate 457 the dynamic regions as well. 458 459- **#define : ADDR\_SPACE\_SIZE** 460 461 Defines the total size of the address space in bytes. For example, for a 32 462 bit address space, this value should be ``(1ull << 32)``. This definition is 463 now deprecated, platforms should use ``PLAT_PHY_ADDR_SPACE_SIZE`` and 464 ``PLAT_VIRT_ADDR_SPACE_SIZE`` instead. 465 466- **#define : PLAT\_VIRT\_ADDR\_SPACE\_SIZE** 467 468 Defines the total size of the virtual address space in bytes. For example, 469 for a 32 bit virtual address space, this value should be ``(1ull << 32)``. 470 471- **#define : PLAT\_PHY\_ADDR\_SPACE\_SIZE** 472 473 Defines the total size of the physical address space in bytes. For example, 474 for a 32 bit physical address space, this value should be ``(1ull << 32)``. 475 476If the platform port uses the IO storage framework, the following constants 477must also be defined: 478 479- **#define : MAX\_IO\_DEVICES** 480 481 Defines the maximum number of registered IO devices. Attempting to register 482 more devices than this value using ``io_register_device()`` will fail with 483 -ENOMEM. 484 485- **#define : MAX\_IO\_HANDLES** 486 487 Defines the maximum number of open IO handles. Attempting to open more IO 488 entities than this value using ``io_open()`` will fail with -ENOMEM. 489 490- **#define : MAX\_IO\_BLOCK\_DEVICES** 491 492 Defines the maximum number of registered IO block devices. Attempting to 493 register more devices this value using ``io_dev_open()`` will fail 494 with -ENOMEM. MAX\_IO\_BLOCK\_DEVICES should be less than MAX\_IO\_DEVICES. 495 With this macro, multiple block devices could be supported at the same 496 time. 497 498If the platform needs to allocate data within the per-cpu data framework in 499BL31, it should define the following macro. Currently this is only required if 500the platform decides not to use the coherent memory section by undefining the 501``USE_COHERENT_MEM`` build flag. In this case, the framework allocates the 502required memory within the the per-cpu data to minimize wastage. 503 504- **#define : PLAT\_PCPU\_DATA\_SIZE** 505 506 Defines the memory (in bytes) to be reserved within the per-cpu data 507 structure for use by the platform layer. 508 509The following constants are optional. They should be defined when the platform 510memory layout implies some image overlaying like in ARM standard platforms. 511 512- **#define : BL31\_PROGBITS\_LIMIT** 513 514 Defines the maximum address in secure RAM that the BL31's progbits sections 515 can occupy. 516 517- **#define : TSP\_PROGBITS\_LIMIT** 518 519 Defines the maximum address that the TSP's progbits sections can occupy. 520 521If the platform port uses the PL061 GPIO driver, the following constant may 522optionally be defined: 523 524- **PLAT\_PL061\_MAX\_GPIOS** 525 Maximum number of GPIOs required by the platform. This allows control how 526 much memory is allocated for PL061 GPIO controllers. The default value is 527 528 #. $(eval $(call add\_define,PLAT\_PL061\_MAX\_GPIOS)) 529 530If the platform port uses the partition driver, the following constant may 531optionally be defined: 532 533- **PLAT\_PARTITION\_MAX\_ENTRIES** 534 Maximum number of partition entries required by the platform. This allows 535 control how much memory is allocated for partition entries. The default 536 value is 128. 537 `For example, define the build flag in platform.mk`_: 538 PLAT\_PARTITION\_MAX\_ENTRIES := 12 539 $(eval $(call add\_define,PLAT\_PARTITION\_MAX\_ENTRIES)) 540 541The following constant is optional. It should be defined to override the default 542behaviour of the ``assert()`` function (for example, to save memory). 543 544- **PLAT\_LOG\_LEVEL\_ASSERT** 545 If ``PLAT_LOG_LEVEL_ASSERT`` is higher or equal than ``LOG_LEVEL_VERBOSE``, 546 ``assert()`` prints the name of the file, the line number and the asserted 547 expression. Else if it is higher than ``LOG_LEVEL_INFO``, it prints the file 548 name and the line number. Else if it is lower than ``LOG_LEVEL_INFO``, it 549 doesn't print anything to the console. If ``PLAT_LOG_LEVEL_ASSERT`` isn't 550 defined, it defaults to ``LOG_LEVEL``. 551 552File : plat\_macros.S [mandatory] 553~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 554 555Each platform must ensure a file of this name is in the system include path with 556the following macro defined. In the ARM development platforms, this file is 557found in ``plat/arm/board/<plat_name>/include/plat_macros.S``. 558 559- **Macro : plat\_crash\_print\_regs** 560 561 This macro allows the crash reporting routine to print relevant platform 562 registers in case of an unhandled exception in BL31. This aids in debugging 563 and this macro can be defined to be empty in case register reporting is not 564 desired. 565 566 For instance, GIC or interconnect registers may be helpful for 567 troubleshooting. 568 569Handling Reset 570-------------- 571 572BL1 by default implements the reset vector where execution starts from a cold 573or warm boot. BL31 can be optionally set as a reset vector using the 574``RESET_TO_BL31`` make variable. 575 576For each CPU, the reset vector code is responsible for the following tasks: 577 578#. Distinguishing between a cold boot and a warm boot. 579 580#. In the case of a cold boot and the CPU being a secondary CPU, ensuring that 581 the CPU is placed in a platform-specific state until the primary CPU 582 performs the necessary steps to remove it from this state. 583 584#. In the case of a warm boot, ensuring that the CPU jumps to a platform- 585 specific address in the BL31 image in the same processor mode as it was 586 when released from reset. 587 588The following functions need to be implemented by the platform port to enable 589reset vector code to perform the above tasks. 590 591Function : plat\_get\_my\_entrypoint() [mandatory when PROGRAMMABLE\_RESET\_ADDRESS == 0] 592~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 593 594:: 595 596 Argument : void 597 Return : uintptr_t 598 599This function is called with the MMU and caches disabled 600(``SCTLR_EL3.M`` = 0 and ``SCTLR_EL3.C`` = 0). The function is responsible for 601distinguishing between a warm and cold reset for the current CPU using 602platform-specific means. If it's a warm reset, then it returns the warm 603reset entrypoint point provided to ``plat_setup_psci_ops()`` during 604BL31 initialization. If it's a cold reset then this function must return zero. 605 606This function does not follow the Procedure Call Standard used by the 607Application Binary Interface for the ARM 64-bit architecture. The caller should 608not assume that callee saved registers are preserved across a call to this 609function. 610 611This function fulfills requirement 1 and 3 listed above. 612 613Note that for platforms that support programming the reset address, it is 614expected that a CPU will start executing code directly at the right address, 615both on a cold and warm reset. In this case, there is no need to identify the 616type of reset nor to query the warm reset entrypoint. Therefore, implementing 617this function is not required on such platforms. 618 619Function : plat\_secondary\_cold\_boot\_setup() [mandatory when COLD\_BOOT\_SINGLE\_CPU == 0] 620~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 621 622:: 623 624 Argument : void 625 626This function is called with the MMU and data caches disabled. It is responsible 627for placing the executing secondary CPU in a platform-specific state until the 628primary CPU performs the necessary actions to bring it out of that state and 629allow entry into the OS. This function must not return. 630 631In the ARM FVP port, when using the normal boot flow, each secondary CPU powers 632itself off. The primary CPU is responsible for powering up the secondary CPUs 633when normal world software requires them. When booting an EL3 payload instead, 634they stay powered on and are put in a holding pen until their mailbox gets 635populated. 636 637This function fulfills requirement 2 above. 638 639Note that for platforms that can't release secondary CPUs out of reset, only the 640primary CPU will execute the cold boot code. Therefore, implementing this 641function is not required on such platforms. 642 643Function : plat\_is\_my\_cpu\_primary() [mandatory when COLD\_BOOT\_SINGLE\_CPU == 0] 644~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 645 646:: 647 648 Argument : void 649 Return : unsigned int 650 651This function identifies whether the current CPU is the primary CPU or a 652secondary CPU. A return value of zero indicates that the CPU is not the 653primary CPU, while a non-zero return value indicates that the CPU is the 654primary CPU. 655 656Note that for platforms that can't release secondary CPUs out of reset, only the 657primary CPU will execute the cold boot code. Therefore, there is no need to 658distinguish between primary and secondary CPUs and implementing this function is 659not required. 660 661Function : platform\_mem\_init() [mandatory] 662~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 663 664:: 665 666 Argument : void 667 Return : void 668 669This function is called before any access to data is made by the firmware, in 670order to carry out any essential memory initialization. 671 672Function: plat\_get\_rotpk\_info() 673~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 674 675:: 676 677 Argument : void *, void **, unsigned int *, unsigned int * 678 Return : int 679 680This function is mandatory when Trusted Board Boot is enabled. It returns a 681pointer to the ROTPK stored in the platform (or a hash of it) and its length. 682The ROTPK must be encoded in DER format according to the following ASN.1 683structure: 684 685:: 686 687 AlgorithmIdentifier ::= SEQUENCE { 688 algorithm OBJECT IDENTIFIER, 689 parameters ANY DEFINED BY algorithm OPTIONAL 690 } 691 692 SubjectPublicKeyInfo ::= SEQUENCE { 693 algorithm AlgorithmIdentifier, 694 subjectPublicKey BIT STRING 695 } 696 697In case the function returns a hash of the key: 698 699:: 700 701 DigestInfo ::= SEQUENCE { 702 digestAlgorithm AlgorithmIdentifier, 703 digest OCTET STRING 704 } 705 706The function returns 0 on success. Any other value is treated as error by the 707Trusted Board Boot. The function also reports extra information related 708to the ROTPK in the flags parameter: 709 710:: 711 712 ROTPK_IS_HASH : Indicates that the ROTPK returned by the platform is a 713 hash. 714 ROTPK_NOT_DEPLOYED : This allows the platform to skip certificate ROTPK 715 verification while the platform ROTPK is not deployed. 716 When this flag is set, the function does not need to 717 return a platform ROTPK, and the authentication 718 framework uses the ROTPK in the certificate without 719 verifying it against the platform value. This flag 720 must not be used in a deployed production environment. 721 722Function: plat\_get\_nv\_ctr() 723~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 724 725:: 726 727 Argument : void *, unsigned int * 728 Return : int 729 730This function is mandatory when Trusted Board Boot is enabled. It returns the 731non-volatile counter value stored in the platform in the second argument. The 732cookie in the first argument may be used to select the counter in case the 733platform provides more than one (for example, on platforms that use the default 734TBBR CoT, the cookie will correspond to the OID values defined in 735TRUSTED\_FW\_NVCOUNTER\_OID or NON\_TRUSTED\_FW\_NVCOUNTER\_OID). 736 737The function returns 0 on success. Any other value means the counter value could 738not be retrieved from the platform. 739 740Function: plat\_set\_nv\_ctr() 741~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 742 743:: 744 745 Argument : void *, unsigned int 746 Return : int 747 748This function is mandatory when Trusted Board Boot is enabled. It sets a new 749counter value in the platform. The cookie in the first argument may be used to 750select the counter (as explained in plat\_get\_nv\_ctr()). The second argument is 751the updated counter value to be written to the NV counter. 752 753The function returns 0 on success. Any other value means the counter value could 754not be updated. 755 756Function: plat\_set\_nv\_ctr2() 757~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 758 759:: 760 761 Argument : void *, const auth_img_desc_t *, unsigned int 762 Return : int 763 764This function is optional when Trusted Board Boot is enabled. If this 765interface is defined, then ``plat_set_nv_ctr()`` need not be defined. The 766first argument passed is a cookie and is typically used to 767differentiate between a Non Trusted NV Counter and a Trusted NV 768Counter. The second argument is a pointer to an authentication image 769descriptor and may be used to decide if the counter is allowed to be 770updated or not. The third argument is the updated counter value to 771be written to the NV counter. 772 773The function returns 0 on success. Any other value means the counter value 774either could not be updated or the authentication image descriptor indicates 775that it is not allowed to be updated. 776 777Common mandatory function modifications 778--------------------------------------- 779 780The following functions are mandatory functions which need to be implemented 781by the platform port. 782 783Function : plat\_my\_core\_pos() 784~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 785 786:: 787 788 Argument : void 789 Return : unsigned int 790 791This funtion returns the index of the calling CPU which is used as a 792CPU-specific linear index into blocks of memory (for example while allocating 793per-CPU stacks). This function will be invoked very early in the 794initialization sequence which mandates that this function should be 795implemented in assembly and should not rely on the avalability of a C 796runtime environment. This function can clobber x0 - x8 and must preserve 797x9 - x29. 798 799This function plays a crucial role in the power domain topology framework in 800PSCI and details of this can be found in `Power Domain Topology Design`_. 801 802Function : plat\_core\_pos\_by\_mpidr() 803~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 804 805:: 806 807 Argument : u_register_t 808 Return : int 809 810This function validates the ``MPIDR`` of a CPU and converts it to an index, 811which can be used as a CPU-specific linear index into blocks of memory. In 812case the ``MPIDR`` is invalid, this function returns -1. This function will only 813be invoked by BL31 after the power domain topology is initialized and can 814utilize the C runtime environment. For further details about how ARM Trusted 815Firmware represents the power domain topology and how this relates to the 816linear CPU index, please refer `Power Domain Topology Design`_. 817 818Common optional modifications 819----------------------------- 820 821The following are helper functions implemented by the firmware that perform 822common platform-specific tasks. A platform may choose to override these 823definitions. 824 825Function : plat\_set\_my\_stack() 826~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 827 828:: 829 830 Argument : void 831 Return : void 832 833This function sets the current stack pointer to the normal memory stack that 834has been allocated for the current CPU. For BL images that only require a 835stack for the primary CPU, the UP version of the function is used. The size 836of the stack allocated to each CPU is specified by the platform defined 837constant ``PLATFORM_STACK_SIZE``. 838 839Common implementations of this function for the UP and MP BL images are 840provided in `plat/common/aarch64/platform\_up\_stack.S`_ and 841`plat/common/aarch64/platform\_mp\_stack.S`_ 842 843Function : plat\_get\_my\_stack() 844~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 845 846:: 847 848 Argument : void 849 Return : uintptr_t 850 851This function returns the base address of the normal memory stack that 852has been allocated for the current CPU. For BL images that only require a 853stack for the primary CPU, the UP version of the function is used. The size 854of the stack allocated to each CPU is specified by the platform defined 855constant ``PLATFORM_STACK_SIZE``. 856 857Common implementations of this function for the UP and MP BL images are 858provided in `plat/common/aarch64/platform\_up\_stack.S`_ and 859`plat/common/aarch64/platform\_mp\_stack.S`_ 860 861Function : plat\_report\_exception() 862~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 863 864:: 865 866 Argument : unsigned int 867 Return : void 868 869A platform may need to report various information about its status when an 870exception is taken, for example the current exception level, the CPU security 871state (secure/non-secure), the exception type, and so on. This function is 872called in the following circumstances: 873 874- In BL1, whenever an exception is taken. 875- In BL2, whenever an exception is taken. 876 877The default implementation doesn't do anything, to avoid making assumptions 878about the way the platform displays its status information. 879 880For AArch64, this function receives the exception type as its argument. 881Possible values for exceptions types are listed in the 882`include/common/bl\_common.h`_ header file. Note that these constants are not 883related to any architectural exception code; they are just an ARM Trusted 884Firmware convention. 885 886For AArch32, this function receives the exception mode as its argument. 887Possible values for exception modes are listed in the 888`include/lib/aarch32/arch.h`_ header file. 889 890Function : plat\_reset\_handler() 891~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 892 893:: 894 895 Argument : void 896 Return : void 897 898A platform may need to do additional initialization after reset. This function 899allows the platform to do the platform specific intializations. Platform 900specific errata workarounds could also be implemented here. The api should 901preserve the values of callee saved registers x19 to x29. 902 903The default implementation doesn't do anything. If a platform needs to override 904the default implementation, refer to the `Firmware Design`_ for general 905guidelines. 906 907Function : plat\_disable\_acp() 908~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 909 910:: 911 912 Argument : void 913 Return : void 914 915This api allows a platform to disable the Accelerator Coherency Port (if 916present) during a cluster power down sequence. The default weak implementation 917doesn't do anything. Since this api is called during the power down sequence, 918it has restrictions for stack usage and it can use the registers x0 - x17 as 919scratch registers. It should preserve the value in x18 register as it is used 920by the caller to store the return address. 921 922Function : plat\_error\_handler() 923~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 924 925:: 926 927 Argument : int 928 Return : void 929 930This API is called when the generic code encounters an error situation from 931which it cannot continue. It allows the platform to perform error reporting or 932recovery actions (for example, reset the system). This function must not return. 933 934The parameter indicates the type of error using standard codes from ``errno.h``. 935Possible errors reported by the generic code are: 936 937- ``-EAUTH``: a certificate or image could not be authenticated (when Trusted 938 Board Boot is enabled) 939- ``-ENOENT``: the requested image or certificate could not be found or an IO 940 error was detected 941- ``-ENOMEM``: resources exhausted. Trusted Firmware does not use dynamic 942 memory, so this error is usually an indication of an incorrect array size 943 944The default implementation simply spins. 945 946Function : plat\_panic\_handler() 947~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 948 949:: 950 951 Argument : void 952 Return : void 953 954This API is called when the generic code encounters an unexpected error 955situation from which it cannot recover. This function must not return, 956and must be implemented in assembly because it may be called before the C 957environment is initialized. 958 959Note: The address from where it was called is stored in x30 (Link Register). 960The default implementation simply spins. 961 962Function : plat\_get\_bl\_image\_load\_info() 963~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 964 965:: 966 967 Argument : void 968 Return : bl_load_info_t * 969 970This function returns pointer to the list of images that the platform has 971populated to load. This function is currently invoked in BL2 to load the 972BL3xx images, when LOAD\_IMAGE\_V2 is enabled. 973 974Function : plat\_get\_next\_bl\_params() 975~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 976 977:: 978 979 Argument : void 980 Return : bl_params_t * 981 982This function returns a pointer to the shared memory that the platform has 983kept aside to pass trusted firmware related information that next BL image 984needs. This function is currently invoked in BL2 to pass this information to 985the next BL image, when LOAD\_IMAGE\_V2 is enabled. 986 987Function : plat\_get\_stack\_protector\_canary() 988~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 989 990:: 991 992 Argument : void 993 Return : u_register_t 994 995This function returns a random value that is used to initialize the canary used 996when the stack protector is enabled with ENABLE\_STACK\_PROTECTOR. A predictable 997value will weaken the protection as the attacker could easily write the right 998value as part of the attack most of the time. Therefore, it should return a 999true random number. 1000 1001Note: For the protection to be effective, the global data need to be placed at 1002a lower address than the stack bases. Failure to do so would allow an attacker 1003to overwrite the canary as part of the stack buffer overflow attack. 1004 1005Function : plat\_flush\_next\_bl\_params() 1006~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1007 1008:: 1009 1010 Argument : void 1011 Return : void 1012 1013This function flushes to main memory all the image params that are passed to 1014next image. This function is currently invoked in BL2 to flush this information 1015to the next BL image, when LOAD\_IMAGE\_V2 is enabled. 1016 1017Function : plat\_log\_get\_prefix() 1018~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1019 1020:: 1021 1022 Argument : unsigned int 1023 Return : const char * 1024 1025This function defines the prefix string corresponding to the `log_level` to be 1026prepended to all the log output from ARM Trusted Firmware. The `log_level` 1027(argument) will correspond to one of the standard log levels defined in 1028debug.h. The platform can override the common implementation to define a 1029different prefix string for the log output. The implementation should be 1030robust to future changes that increase the number of log levels. 1031 1032Modifications specific to a Boot Loader stage 1033--------------------------------------------- 1034 1035Boot Loader Stage 1 (BL1) 1036------------------------- 1037 1038BL1 implements the reset vector where execution starts from after a cold or 1039warm boot. For each CPU, BL1 is responsible for the following tasks: 1040 1041#. Handling the reset as described in section 2.2 1042 1043#. In the case of a cold boot and the CPU being the primary CPU, ensuring that 1044 only this CPU executes the remaining BL1 code, including loading and passing 1045 control to the BL2 stage. 1046 1047#. Identifying and starting the Firmware Update process (if required). 1048 1049#. Loading the BL2 image from non-volatile storage into secure memory at the 1050 address specified by the platform defined constant ``BL2_BASE``. 1051 1052#. Populating a ``meminfo`` structure with the following information in memory, 1053 accessible by BL2 immediately upon entry. 1054 1055 :: 1056 1057 meminfo.total_base = Base address of secure RAM visible to BL2 1058 meminfo.total_size = Size of secure RAM visible to BL2 1059 meminfo.free_base = Base address of secure RAM available for 1060 allocation to BL2 1061 meminfo.free_size = Size of secure RAM available for allocation to BL2 1062 1063 BL1 places this ``meminfo`` structure at the beginning of the free memory 1064 available for its use. Since BL1 cannot allocate memory dynamically at the 1065 moment, its free memory will be available for BL2's use as-is. However, this 1066 means that BL2 must read the ``meminfo`` structure before it starts using its 1067 free memory (this is discussed in Section 3.2). 1068 1069 In future releases of the ARM Trusted Firmware it will be possible for 1070 the platform to decide where it wants to place the ``meminfo`` structure for 1071 BL2. 1072 1073 BL1 implements the ``bl1_init_bl2_mem_layout()`` function to populate the 1074 BL2 ``meminfo`` structure. The platform may override this implementation, for 1075 example if the platform wants to restrict the amount of memory visible to 1076 BL2. Details of how to do this are given below. 1077 1078The following functions need to be implemented by the platform port to enable 1079BL1 to perform the above tasks. 1080 1081Function : bl1\_early\_platform\_setup() [mandatory] 1082~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1083 1084:: 1085 1086 Argument : void 1087 Return : void 1088 1089This function executes with the MMU and data caches disabled. It is only called 1090by the primary CPU. 1091 1092On ARM standard platforms, this function: 1093 1094- Enables a secure instance of SP805 to act as the Trusted Watchdog. 1095 1096- Initializes a UART (PL011 console), which enables access to the ``printf`` 1097 family of functions in BL1. 1098 1099- Enables issuing of snoop and DVM (Distributed Virtual Memory) requests to 1100 the CCI slave interface corresponding to the cluster that includes the 1101 primary CPU. 1102 1103Function : bl1\_plat\_arch\_setup() [mandatory] 1104~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1105 1106:: 1107 1108 Argument : void 1109 Return : void 1110 1111This function performs any platform-specific and architectural setup that the 1112platform requires. Platform-specific setup might include configuration of 1113memory controllers and the interconnect. 1114 1115In ARM standard platforms, this function enables the MMU. 1116 1117This function helps fulfill requirement 2 above. 1118 1119Function : bl1\_platform\_setup() [mandatory] 1120~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1121 1122:: 1123 1124 Argument : void 1125 Return : void 1126 1127This function executes with the MMU and data caches enabled. It is responsible 1128for performing any remaining platform-specific setup that can occur after the 1129MMU and data cache have been enabled. 1130 1131if support for multiple boot sources is required, it initializes the boot 1132sequence used by plat\_try\_next\_boot\_source(). 1133 1134In ARM standard platforms, this function initializes the storage abstraction 1135layer used to load the next bootloader image. 1136 1137This function helps fulfill requirement 4 above. 1138 1139Function : bl1\_plat\_sec\_mem\_layout() [mandatory] 1140~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1141 1142:: 1143 1144 Argument : void 1145 Return : meminfo * 1146 1147This function should only be called on the cold boot path. It executes with the 1148MMU and data caches enabled. The pointer returned by this function must point to 1149a ``meminfo`` structure containing the extents and availability of secure RAM for 1150the BL1 stage. 1151 1152:: 1153 1154 meminfo.total_base = Base address of secure RAM visible to BL1 1155 meminfo.total_size = Size of secure RAM visible to BL1 1156 meminfo.free_base = Base address of secure RAM available for allocation 1157 to BL1 1158 meminfo.free_size = Size of secure RAM available for allocation to BL1 1159 1160This information is used by BL1 to load the BL2 image in secure RAM. BL1 also 1161populates a similar structure to tell BL2 the extents of memory available for 1162its own use. 1163 1164This function helps fulfill requirements 4 and 5 above. 1165 1166Function : bl1\_init\_bl2\_mem\_layout() [optional] 1167~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1168 1169:: 1170 1171 Argument : meminfo *, meminfo * 1172 Return : void 1173 1174BL1 needs to tell the next stage the amount of secure RAM available 1175for it to use. This information is populated in a ``meminfo`` 1176structure. 1177 1178Depending upon where BL2 has been loaded in secure RAM (determined by 1179``BL2_BASE``), BL1 calculates the amount of free memory available for BL2 to use. 1180BL1 also ensures that its data sections resident in secure RAM are not visible 1181to BL2. An illustration of how this is done in ARM standard platforms is given 1182in the **Memory layout on ARM development platforms** section in the 1183`Firmware Design`_. 1184 1185Function : bl1\_plat\_prepare\_exit() [optional] 1186~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1187 1188:: 1189 1190 Argument : entry_point_info_t * 1191 Return : void 1192 1193This function is called prior to exiting BL1 in response to the 1194``BL1_SMC_RUN_IMAGE`` SMC request raised by BL2. It should be used to perform 1195platform specific clean up or bookkeeping operations before transferring 1196control to the next image. It receives the address of the ``entry_point_info_t`` 1197structure passed from BL2. This function runs with MMU disabled. 1198 1199Function : bl1\_plat\_set\_ep\_info() [optional] 1200~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1201 1202:: 1203 1204 Argument : unsigned int image_id, entry_point_info_t *ep_info 1205 Return : void 1206 1207This function allows platforms to override ``ep_info`` for the given ``image_id``. 1208 1209The default implementation just returns. 1210 1211Function : bl1\_plat\_get\_next\_image\_id() [optional] 1212~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1213 1214:: 1215 1216 Argument : void 1217 Return : unsigned int 1218 1219This and the following function must be overridden to enable the FWU feature. 1220 1221BL1 calls this function after platform setup to identify the next image to be 1222loaded and executed. If the platform returns ``BL2_IMAGE_ID`` then BL1 proceeds 1223with the normal boot sequence, which loads and executes BL2. If the platform 1224returns a different image id, BL1 assumes that Firmware Update is required. 1225 1226The default implementation always returns ``BL2_IMAGE_ID``. The ARM development 1227platforms override this function to detect if firmware update is required, and 1228if so, return the first image in the firmware update process. 1229 1230Function : bl1\_plat\_get\_image\_desc() [optional] 1231~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1232 1233:: 1234 1235 Argument : unsigned int image_id 1236 Return : image_desc_t * 1237 1238BL1 calls this function to get the image descriptor information ``image_desc_t`` 1239for the provided ``image_id`` from the platform. 1240 1241The default implementation always returns a common BL2 image descriptor. ARM 1242standard platforms return an image descriptor corresponding to BL2 or one of 1243the firmware update images defined in the Trusted Board Boot Requirements 1244specification. 1245 1246Function : bl1\_plat\_fwu\_done() [optional] 1247~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1248 1249:: 1250 1251 Argument : unsigned int image_id, uintptr_t image_src, 1252 unsigned int image_size 1253 Return : void 1254 1255BL1 calls this function when the FWU process is complete. It must not return. 1256The platform may override this function to take platform specific action, for 1257example to initiate the normal boot flow. 1258 1259The default implementation spins forever. 1260 1261Function : bl1\_plat\_mem\_check() [mandatory] 1262~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1263 1264:: 1265 1266 Argument : uintptr_t mem_base, unsigned int mem_size, 1267 unsigned int flags 1268 Return : int 1269 1270BL1 calls this function while handling FWU related SMCs, more specifically when 1271copying or authenticating an image. Its responsibility is to ensure that the 1272region of memory identified by ``mem_base`` and ``mem_size`` is mapped in BL1, and 1273that this memory corresponds to either a secure or non-secure memory region as 1274indicated by the security state of the ``flags`` argument. 1275 1276This function can safely assume that the value resulting from the addition of 1277``mem_base`` and ``mem_size`` fits into a ``uintptr_t`` type variable and does not 1278overflow. 1279 1280This function must return 0 on success, a non-null error code otherwise. 1281 1282The default implementation of this function asserts therefore platforms must 1283override it when using the FWU feature. 1284 1285Boot Loader Stage 2 (BL2) 1286------------------------- 1287 1288The BL2 stage is executed only by the primary CPU, which is determined in BL1 1289using the ``platform_is_primary_cpu()`` function. BL1 passed control to BL2 at 1290``BL2_BASE``. BL2 executes in Secure EL1 and is responsible for: 1291 1292#. (Optional) Loading the SCP\_BL2 binary image (if present) from platform 1293 provided non-volatile storage. To load the SCP\_BL2 image, BL2 makes use of 1294 the ``meminfo`` returned by the ``bl2_plat_get_scp_bl2_meminfo()`` function. 1295 The platform also defines the address in memory where SCP\_BL2 is loaded 1296 through the optional constant ``SCP_BL2_BASE``. BL2 uses this information 1297 to determine if there is enough memory to load the SCP\_BL2 image. 1298 Subsequent handling of the SCP\_BL2 image is platform-specific and is 1299 implemented in the ``bl2_plat_handle_scp_bl2()`` function. 1300 If ``SCP_BL2_BASE`` is not defined then this step is not performed. 1301 1302#. Loading the BL31 binary image into secure RAM from non-volatile storage. To 1303 load the BL31 image, BL2 makes use of the ``meminfo`` structure passed to it 1304 by BL1. This structure allows BL2 to calculate how much secure RAM is 1305 available for its use. The platform also defines the address in secure RAM 1306 where BL31 is loaded through the constant ``BL31_BASE``. BL2 uses this 1307 information to determine if there is enough memory to load the BL31 image. 1308 1309#. (Optional) Loading the BL32 binary image (if present) from platform 1310 provided non-volatile storage. To load the BL32 image, BL2 makes use of 1311 the ``meminfo`` returned by the ``bl2_plat_get_bl32_meminfo()`` function. 1312 The platform also defines the address in memory where BL32 is loaded 1313 through the optional constant ``BL32_BASE``. BL2 uses this information 1314 to determine if there is enough memory to load the BL32 image. 1315 If ``BL32_BASE`` is not defined then this and the next step is not performed. 1316 1317#. (Optional) Arranging to pass control to the BL32 image (if present) that 1318 has been pre-loaded at ``BL32_BASE``. BL2 populates an ``entry_point_info`` 1319 structure in memory provided by the platform with information about how 1320 BL31 should pass control to the BL32 image. 1321 1322#. (Optional) Loading the normal world BL33 binary image (if not loaded by 1323 other means) into non-secure DRAM from platform storage and arranging for 1324 BL31 to pass control to this image. This address is determined using the 1325 ``plat_get_ns_image_entrypoint()`` function described below. 1326 1327#. BL2 populates an ``entry_point_info`` structure in memory provided by the 1328 platform with information about how BL31 should pass control to the 1329 other BL images. 1330 1331The following functions must be implemented by the platform port to enable BL2 1332to perform the above tasks. 1333 1334Function : bl2\_early\_platform\_setup() [mandatory] 1335~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1336 1337:: 1338 1339 Argument : meminfo * 1340 Return : void 1341 1342This function executes with the MMU and data caches disabled. It is only called 1343by the primary CPU. The arguments to this function is the address of the 1344``meminfo`` structure populated by BL1. 1345 1346The platform may copy the contents of the ``meminfo`` structure into a private 1347variable as the original memory may be subsequently overwritten by BL2. The 1348copied structure is made available to all BL2 code through the 1349``bl2_plat_sec_mem_layout()`` function. 1350 1351On ARM standard platforms, this function also: 1352 1353- Initializes a UART (PL011 console), which enables access to the ``printf`` 1354 family of functions in BL2. 1355 1356- Initializes the storage abstraction layer used to load further bootloader 1357 images. It is necessary to do this early on platforms with a SCP\_BL2 image, 1358 since the later ``bl2_platform_setup`` must be done after SCP\_BL2 is loaded. 1359 1360Function : bl2\_plat\_arch\_setup() [mandatory] 1361~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1362 1363:: 1364 1365 Argument : void 1366 Return : void 1367 1368This function executes with the MMU and data caches disabled. It is only called 1369by the primary CPU. 1370 1371The purpose of this function is to perform any architectural initialization 1372that varies across platforms. 1373 1374On ARM standard platforms, this function enables the MMU. 1375 1376Function : bl2\_platform\_setup() [mandatory] 1377~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1378 1379:: 1380 1381 Argument : void 1382 Return : void 1383 1384This function may execute with the MMU and data caches enabled if the platform 1385port does the necessary initialization in ``bl2_plat_arch_setup()``. It is only 1386called by the primary CPU. 1387 1388The purpose of this function is to perform any platform initialization 1389specific to BL2. 1390 1391In ARM standard platforms, this function performs security setup, including 1392configuration of the TrustZone controller to allow non-secure masters access 1393to most of DRAM. Part of DRAM is reserved for secure world use. 1394 1395Function : bl2\_plat\_sec\_mem\_layout() [mandatory] 1396~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1397 1398:: 1399 1400 Argument : void 1401 Return : meminfo * 1402 1403This function should only be called on the cold boot path. It may execute with 1404the MMU and data caches enabled if the platform port does the necessary 1405initialization in ``bl2_plat_arch_setup()``. It is only called by the primary CPU. 1406 1407The purpose of this function is to return a pointer to a ``meminfo`` structure 1408populated with the extents of secure RAM available for BL2 to use. See 1409``bl2_early_platform_setup()`` above. 1410 1411Following function is required only when LOAD\_IMAGE\_V2 is enabled. 1412 1413Function : bl2\_plat\_handle\_post\_image\_load() [mandatory] 1414~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1415 1416:: 1417 1418 Argument : unsigned int 1419 Return : int 1420 1421This function can be used by the platforms to update/use image information 1422for given ``image_id``. This function is currently invoked in BL2 to handle 1423BL image specific information based on the ``image_id`` passed, when 1424LOAD\_IMAGE\_V2 is enabled. 1425 1426Following functions are required only when LOAD\_IMAGE\_V2 is disabled. 1427 1428Function : bl2\_plat\_get\_scp\_bl2\_meminfo() [mandatory] 1429~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1430 1431:: 1432 1433 Argument : meminfo * 1434 Return : void 1435 1436This function is used to get the memory limits where BL2 can load the 1437SCP\_BL2 image. The meminfo provided by this is used by load\_image() to 1438validate whether the SCP\_BL2 image can be loaded within the given 1439memory from the given base. 1440 1441Function : bl2\_plat\_handle\_scp\_bl2() [mandatory] 1442~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1443 1444:: 1445 1446 Argument : image_info * 1447 Return : int 1448 1449This function is called after loading SCP\_BL2 image and it is used to perform 1450any platform-specific actions required to handle the SCP firmware. Typically it 1451transfers the image into SCP memory using a platform-specific protocol and waits 1452until SCP executes it and signals to the Application Processor (AP) for BL2 1453execution to continue. 1454 1455This function returns 0 on success, a negative error code otherwise. 1456 1457Function : bl2\_plat\_get\_bl31\_params() [mandatory] 1458~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1459 1460:: 1461 1462 Argument : void 1463 Return : bl31_params * 1464 1465BL2 platform code needs to return a pointer to a ``bl31_params`` structure it 1466will use for passing information to BL31. The ``bl31_params`` structure carries 1467the following information. 1468- Header describing the version information for interpreting the bl31\_param 1469structure 1470- Information about executing the BL33 image in the ``bl33_ep_info`` field 1471- Information about executing the BL32 image in the ``bl32_ep_info`` field 1472- Information about the type and extents of BL31 image in the 1473``bl31_image_info`` field 1474- Information about the type and extents of BL32 image in the 1475``bl32_image_info`` field 1476- Information about the type and extents of BL33 image in the 1477``bl33_image_info`` field 1478 1479The memory pointed by this structure and its sub-structures should be 1480accessible from BL31 initialisation code. BL31 might choose to copy the 1481necessary content, or maintain the structures until BL33 is initialised. 1482 1483Funtion : bl2\_plat\_get\_bl31\_ep\_info() [mandatory] 1484~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1485 1486:: 1487 1488 Argument : void 1489 Return : entry_point_info * 1490 1491BL2 platform code returns a pointer which is used to populate the entry point 1492information for BL31 entry point. The location pointed by it should be 1493accessible from BL1 while processing the synchronous exception to run to BL31. 1494 1495In ARM standard platforms this is allocated inside a bl2\_to\_bl31\_params\_mem 1496structure in BL2 memory. 1497 1498Function : bl2\_plat\_set\_bl31\_ep\_info() [mandatory] 1499~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1500 1501:: 1502 1503 Argument : image_info *, entry_point_info * 1504 Return : void 1505 1506In the normal boot flow, this function is called after loading BL31 image and 1507it can be used to overwrite the entry point set by loader and also set the 1508security state and SPSR which represents the entry point system state for BL31. 1509 1510When booting an EL3 payload instead, this function is called after populating 1511its entry point address and can be used for the same purpose for the payload 1512image. It receives a null pointer as its first argument in this case. 1513 1514Function : bl2\_plat\_set\_bl32\_ep\_info() [mandatory] 1515~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1516 1517:: 1518 1519 Argument : image_info *, entry_point_info * 1520 Return : void 1521 1522This function is called after loading BL32 image and it can be used to 1523overwrite the entry point set by loader and also set the security state 1524and SPSR which represents the entry point system state for BL32. 1525 1526Function : bl2\_plat\_set\_bl33\_ep\_info() [mandatory] 1527~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1528 1529:: 1530 1531 Argument : image_info *, entry_point_info * 1532 Return : void 1533 1534This function is called after loading BL33 image and it can be used to 1535overwrite the entry point set by loader and also set the security state 1536and SPSR which represents the entry point system state for BL33. 1537 1538In the preloaded BL33 alternative boot flow, this function is called after 1539populating its entry point address. It is passed a null pointer as its first 1540argument in this case. 1541 1542Function : bl2\_plat\_get\_bl32\_meminfo() [mandatory] 1543~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1544 1545:: 1546 1547 Argument : meminfo * 1548 Return : void 1549 1550This function is used to get the memory limits where BL2 can load the 1551BL32 image. The meminfo provided by this is used by load\_image() to 1552validate whether the BL32 image can be loaded with in the given 1553memory from the given base. 1554 1555Function : bl2\_plat\_get\_bl33\_meminfo() [mandatory] 1556~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1557 1558:: 1559 1560 Argument : meminfo * 1561 Return : void 1562 1563This function is used to get the memory limits where BL2 can load the 1564BL33 image. The meminfo provided by this is used by load\_image() to 1565validate whether the BL33 image can be loaded with in the given 1566memory from the given base. 1567 1568This function isn't needed if either ``PRELOADED_BL33_BASE`` or ``EL3_PAYLOAD_BASE`` 1569build options are used. 1570 1571Function : bl2\_plat\_flush\_bl31\_params() [mandatory] 1572~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1573 1574:: 1575 1576 Argument : void 1577 Return : void 1578 1579Once BL2 has populated all the structures that needs to be read by BL1 1580and BL31 including the bl31\_params structures and its sub-structures, 1581the bl31\_ep\_info structure and any platform specific data. It flushes 1582all these data to the main memory so that it is available when we jump to 1583later Bootloader stages with MMU off 1584 1585Function : plat\_get\_ns\_image\_entrypoint() [mandatory] 1586~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1587 1588:: 1589 1590 Argument : void 1591 Return : uintptr_t 1592 1593As previously described, BL2 is responsible for arranging for control to be 1594passed to a normal world BL image through BL31. This function returns the 1595entrypoint of that image, which BL31 uses to jump to it. 1596 1597BL2 is responsible for loading the normal world BL33 image (e.g. UEFI). 1598 1599This function isn't needed if either ``PRELOADED_BL33_BASE`` or ``EL3_PAYLOAD_BASE`` 1600build options are used. 1601 1602Function : bl2\_plat\_preload\_setup [optional] 1603~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1604 1605:: 1606 Argument : void 1607 Return : void 1608 1609This optional function performs any BL2 platform initialization 1610required before image loading, that is not done later in 1611bl2\_platform\_setup(). Specifically, if support for multiple 1612boot sources is required, it initializes the boot sequence used by 1613plat\_try\_next\_boot\_source(). 1614 1615Function : plat\_try\_next\_boot\_source() [optional] 1616~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1617 1618:: 1619 Argument : void 1620 Return : int 1621 1622This optional function passes to the next boot source in the redundancy 1623sequence. 1624 1625This function moves the current boot redundancy source to the next 1626element in the boot sequence. If there are no more boot sources then it 1627must return 0, otherwise it must return 1. The default implementation 1628of this always returns 0. 1629 1630FWU Boot Loader Stage 2 (BL2U) 1631------------------------------ 1632 1633The AP Firmware Updater Configuration, BL2U, is an optional part of the FWU 1634process and is executed only by the primary CPU. BL1 passes control to BL2U at 1635``BL2U_BASE``. BL2U executes in Secure-EL1 and is responsible for: 1636 1637#. (Optional) Transfering the optional SCP\_BL2U binary image from AP secure 1638 memory to SCP RAM. BL2U uses the SCP\_BL2U ``image_info`` passed by BL1. 1639 ``SCP_BL2U_BASE`` defines the address in AP secure memory where SCP\_BL2U 1640 should be copied from. Subsequent handling of the SCP\_BL2U image is 1641 implemented by the platform specific ``bl2u_plat_handle_scp_bl2u()`` function. 1642 If ``SCP_BL2U_BASE`` is not defined then this step is not performed. 1643 1644#. Any platform specific setup required to perform the FWU process. For 1645 example, ARM standard platforms initialize the TZC controller so that the 1646 normal world can access DDR memory. 1647 1648The following functions must be implemented by the platform port to enable 1649BL2U to perform the tasks mentioned above. 1650 1651Function : bl2u\_early\_platform\_setup() [mandatory] 1652~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1653 1654:: 1655 1656 Argument : meminfo *mem_info, void *plat_info 1657 Return : void 1658 1659This function executes with the MMU and data caches disabled. It is only 1660called by the primary CPU. The arguments to this function is the address 1661of the ``meminfo`` structure and platform specific info provided by BL1. 1662 1663The platform may copy the contents of the ``mem_info`` and ``plat_info`` into 1664private storage as the original memory may be subsequently overwritten by BL2U. 1665 1666On ARM CSS platforms ``plat_info`` is interpreted as an ``image_info_t`` structure, 1667to extract SCP\_BL2U image information, which is then copied into a private 1668variable. 1669 1670Function : bl2u\_plat\_arch\_setup() [mandatory] 1671~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1672 1673:: 1674 1675 Argument : void 1676 Return : void 1677 1678This function executes with the MMU and data caches disabled. It is only 1679called by the primary CPU. 1680 1681The purpose of this function is to perform any architectural initialization 1682that varies across platforms, for example enabling the MMU (since the memory 1683map differs across platforms). 1684 1685Function : bl2u\_platform\_setup() [mandatory] 1686~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1687 1688:: 1689 1690 Argument : void 1691 Return : void 1692 1693This function may execute with the MMU and data caches enabled if the platform 1694port does the necessary initialization in ``bl2u_plat_arch_setup()``. It is only 1695called by the primary CPU. 1696 1697The purpose of this function is to perform any platform initialization 1698specific to BL2U. 1699 1700In ARM standard platforms, this function performs security setup, including 1701configuration of the TrustZone controller to allow non-secure masters access 1702to most of DRAM. Part of DRAM is reserved for secure world use. 1703 1704Function : bl2u\_plat\_handle\_scp\_bl2u() [optional] 1705~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1706 1707:: 1708 1709 Argument : void 1710 Return : int 1711 1712This function is used to perform any platform-specific actions required to 1713handle the SCP firmware. Typically it transfers the image into SCP memory using 1714a platform-specific protocol and waits until SCP executes it and signals to the 1715Application Processor (AP) for BL2U execution to continue. 1716 1717This function returns 0 on success, a negative error code otherwise. 1718This function is included if SCP\_BL2U\_BASE is defined. 1719 1720Boot Loader Stage 3-1 (BL31) 1721---------------------------- 1722 1723During cold boot, the BL31 stage is executed only by the primary CPU. This is 1724determined in BL1 using the ``platform_is_primary_cpu()`` function. BL1 passes 1725control to BL31 at ``BL31_BASE``. During warm boot, BL31 is executed by all 1726CPUs. BL31 executes at EL3 and is responsible for: 1727 1728#. Re-initializing all architectural and platform state. Although BL1 performs 1729 some of this initialization, BL31 remains resident in EL3 and must ensure 1730 that EL3 architectural and platform state is completely initialized. It 1731 should make no assumptions about the system state when it receives control. 1732 1733#. Passing control to a normal world BL image, pre-loaded at a platform- 1734 specific address by BL2. BL31 uses the ``entry_point_info`` structure that BL2 1735 populated in memory to do this. 1736 1737#. Providing runtime firmware services. Currently, BL31 only implements a 1738 subset of the Power State Coordination Interface (PSCI) API as a runtime 1739 service. See Section 3.3 below for details of porting the PSCI 1740 implementation. 1741 1742#. Optionally passing control to the BL32 image, pre-loaded at a platform- 1743 specific address by BL2. BL31 exports a set of apis that allow runtime 1744 services to specify the security state in which the next image should be 1745 executed and run the corresponding image. BL31 uses the ``entry_point_info`` 1746 structure populated by BL2 to do this. 1747 1748If BL31 is a reset vector, It also needs to handle the reset as specified in 1749section 2.2 before the tasks described above. 1750 1751The following functions must be implemented by the platform port to enable BL31 1752to perform the above tasks. 1753 1754Function : bl31\_early\_platform\_setup() [mandatory] 1755~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1756 1757:: 1758 1759 Argument : bl31_params *, void * 1760 Return : void 1761 1762This function executes with the MMU and data caches disabled. It is only called 1763by the primary CPU. The arguments to this function are: 1764 1765- The address of the ``bl31_params`` structure populated by BL2. 1766- An opaque pointer that the platform may use as needed. 1767 1768The platform can copy the contents of the ``bl31_params`` structure and its 1769sub-structures into private variables if the original memory may be 1770subsequently overwritten by BL31 and similarly the ``void *`` pointing 1771to the platform data also needs to be saved. 1772 1773In ARM standard platforms, BL2 passes a pointer to a ``bl31_params`` structure 1774in BL2 memory. BL31 copies the information in this pointer to internal data 1775structures. It also performs the following: 1776 1777- Initialize a UART (PL011 console), which enables access to the ``printf`` 1778 family of functions in BL31. 1779 1780- Enable issuing of snoop and DVM (Distributed Virtual Memory) requests to the 1781 CCI slave interface corresponding to the cluster that includes the primary 1782 CPU. 1783 1784Function : bl31\_plat\_arch\_setup() [mandatory] 1785~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1786 1787:: 1788 1789 Argument : void 1790 Return : void 1791 1792This function executes with the MMU and data caches disabled. It is only called 1793by the primary CPU. 1794 1795The purpose of this function is to perform any architectural initialization 1796that varies across platforms. 1797 1798On ARM standard platforms, this function enables the MMU. 1799 1800Function : bl31\_platform\_setup() [mandatory] 1801~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1802 1803:: 1804 1805 Argument : void 1806 Return : void 1807 1808This function may execute with the MMU and data caches enabled if the platform 1809port does the necessary initialization in ``bl31_plat_arch_setup()``. It is only 1810called by the primary CPU. 1811 1812The purpose of this function is to complete platform initialization so that both 1813BL31 runtime services and normal world software can function correctly. 1814 1815On ARM standard platforms, this function does the following: 1816 1817- Initialize the generic interrupt controller. 1818 1819 Depending on the GIC driver selected by the platform, the appropriate GICv2 1820 or GICv3 initialization will be done, which mainly consists of: 1821 1822 - Enable secure interrupts in the GIC CPU interface. 1823 - Disable the legacy interrupt bypass mechanism. 1824 - Configure the priority mask register to allow interrupts of all priorities 1825 to be signaled to the CPU interface. 1826 - Mark SGIs 8-15 and the other secure interrupts on the platform as secure. 1827 - Target all secure SPIs to CPU0. 1828 - Enable these secure interrupts in the GIC distributor. 1829 - Configure all other interrupts as non-secure. 1830 - Enable signaling of secure interrupts in the GIC distributor. 1831 1832- Enable system-level implementation of the generic timer counter through the 1833 memory mapped interface. 1834 1835- Grant access to the system counter timer module 1836 1837- Initialize the power controller device. 1838 1839 In particular, initialise the locks that prevent concurrent accesses to the 1840 power controller device. 1841 1842Function : bl31\_plat\_runtime\_setup() [optional] 1843~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1844 1845:: 1846 1847 Argument : void 1848 Return : void 1849 1850The purpose of this function is allow the platform to perform any BL31 runtime 1851setup just prior to BL31 exit during cold boot. The default weak 1852implementation of this function will invoke ``console_uninit()`` which will 1853suppress any BL31 runtime logs. 1854 1855In ARM Standard platforms, this function will initialize the BL31 runtime 1856console which will cause all further BL31 logs to be output to the 1857runtime console. 1858 1859Function : bl31\_get\_next\_image\_info() [mandatory] 1860~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1861 1862:: 1863 1864 Argument : unsigned int 1865 Return : entry_point_info * 1866 1867This function may execute with the MMU and data caches enabled if the platform 1868port does the necessary initializations in ``bl31_plat_arch_setup()``. 1869 1870This function is called by ``bl31_main()`` to retrieve information provided by 1871BL2 for the next image in the security state specified by the argument. BL31 1872uses this information to pass control to that image in the specified security 1873state. This function must return a pointer to the ``entry_point_info`` structure 1874(that was copied during ``bl31_early_platform_setup()``) if the image exists. It 1875should return NULL otherwise. 1876 1877Function : plat\_get\_syscnt\_freq2() [mandatory] 1878~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1879 1880:: 1881 1882 Argument : void 1883 Return : unsigned int 1884 1885This function is used by the architecture setup code to retrieve the counter 1886frequency for the CPU's generic timer. This value will be programmed into the 1887``CNTFRQ_EL0`` register. In ARM standard platforms, it returns the base frequency 1888of the system counter, which is retrieved from the first entry in the frequency 1889modes table. 1890 1891#define : PLAT\_PERCPU\_BAKERY\_LOCK\_SIZE [optional] 1892~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1893 1894When ``USE_COHERENT_MEM = 0``, this constant defines the total memory (in 1895bytes) aligned to the cache line boundary that should be allocated per-cpu to 1896accommodate all the bakery locks. 1897 1898If this constant is not defined when ``USE_COHERENT_MEM = 0``, the linker 1899calculates the size of the ``bakery_lock`` input section, aligns it to the 1900nearest ``CACHE_WRITEBACK_GRANULE``, multiplies it with ``PLATFORM_CORE_COUNT`` 1901and stores the result in a linker symbol. This constant prevents a platform 1902from relying on the linker and provide a more efficient mechanism for 1903accessing per-cpu bakery lock information. 1904 1905If this constant is defined and its value is not equal to the value 1906calculated by the linker then a link time assertion is raised. A compile time 1907assertion is raised if the value of the constant is not aligned to the cache 1908line boundary. 1909 1910SDEI porting requirements 1911~~~~~~~~~~~~~~~~~~~~~~~~~ 1912 1913The SDEI dispatcher requires the platform to provide the following macros 1914and functions, of which some are optional, and some others mandatory. 1915 1916Macros 1917...... 1918 1919Macro: PLAT_SDEI_NORMAL_PRI [mandatory] 1920^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 1921 1922This macro must be defined to the EL3 exception priority level associated with 1923Normal SDEI events on the platform. This must have a higher value (therefore of 1924lower priority) than ``PLAT_SDEI_CRITICAL_PRI``. 1925 1926Macro: PLAT_SDEI_CRITICAL_PRI [mandatory] 1927^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 1928 1929This macro must be defined to the EL3 exception priority level associated with 1930Critical SDEI events on the platform. This must have a lower value (therefore of 1931higher priority) than ``PLAT_SDEI_NORMAL_PRI``. 1932 1933It's recommended that SDEI exception priorities in general are assigned the 1934lowest among Secure priorities. Among the SDEI exceptions, Critical SDEI 1935priority must be higher than Normal SDEI priority. 1936 1937Functions 1938......... 1939 1940Function: int plat_sdei_validate_entry_point(uintptr_t ep) [optional] 1941^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 1942 1943:: 1944 1945 Argument: uintptr_t 1946 Return: int 1947 1948This function validates the address of client entry points provided for both 1949event registration and *Complete and Resume* SDEI calls. The function takes one 1950argument, which is the address of the handler the SDEI client requested to 1951register. The function must return ``0`` for successful validation, or ``-1`` 1952upon failure. 1953 1954The default implementation always returns ``0``. On ARM platforms, this function 1955is implemented to translate the entry point to physical address, and further to 1956ensure that the address is located in Non-secure DRAM. 1957 1958Function: void plat_sdei_handle_masked_trigger(uint64_t mpidr, unsigned int intr) [optional] 1959^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 1960 1961:: 1962 1963 Argument: uint64_t 1964 Argument: unsigned int 1965 Return: void 1966 1967SDEI specification requires that a PE comes out of reset with the events masked. 1968The client therefore is expected to call ``PE_UNMASK`` to unmask SDEI events on 1969the PE. No SDEI events can be dispatched until such time. 1970 1971Should a PE receive an interrupt that was bound to an SDEI event while the 1972events are masked on the PE, the dispatcher implementation invokes the function 1973``plat_sdei_handle_masked_trigger``. The MPIDR of the PE that received the 1974interrupt and the interrupt ID are passed as parameters. 1975 1976The default implementation only prints out a warning message. 1977 1978Power State Coordination Interface (in BL31) 1979-------------------------------------------- 1980 1981The ARM Trusted Firmware's implementation of the PSCI API is based around the 1982concept of a *power domain*. A *power domain* is a CPU or a logical group of 1983CPUs which share some state on which power management operations can be 1984performed as specified by `PSCI`_. Each CPU in the system is assigned a cpu 1985index which is a unique number between ``0`` and ``PLATFORM_CORE_COUNT - 1``. 1986The *power domains* are arranged in a hierarchical tree structure and 1987each *power domain* can be identified in a system by the cpu index of any CPU 1988that is part of that domain and a *power domain level*. A processing element 1989(for example, a CPU) is at level 0. If the *power domain* node above a CPU is 1990a logical grouping of CPUs that share some state, then level 1 is that group 1991of CPUs (for example, a cluster), and level 2 is a group of clusters 1992(for example, the system). More details on the power domain topology and its 1993organization can be found in `Power Domain Topology Design`_. 1994 1995BL31's platform initialization code exports a pointer to the platform-specific 1996power management operations required for the PSCI implementation to function 1997correctly. This information is populated in the ``plat_psci_ops`` structure. The 1998PSCI implementation calls members of the ``plat_psci_ops`` structure for performing 1999power management operations on the power domains. For example, the target 2000CPU is specified by its ``MPIDR`` in a PSCI ``CPU_ON`` call. The ``pwr_domain_on()`` 2001handler (if present) is called for the CPU power domain. 2002 2003The ``power-state`` parameter of a PSCI ``CPU_SUSPEND`` call can be used to 2004describe composite power states specific to a platform. The PSCI implementation 2005defines a generic representation of the power-state parameter viz which is an 2006array of local power states where each index corresponds to a power domain 2007level. Each entry contains the local power state the power domain at that power 2008level could enter. It depends on the ``validate_power_state()`` handler to 2009convert the power-state parameter (possibly encoding a composite power state) 2010passed in a PSCI ``CPU_SUSPEND`` call to this representation. 2011 2012The following functions form part of platform port of PSCI functionality. 2013 2014Function : plat\_psci\_stat\_accounting\_start() [optional] 2015~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2016 2017:: 2018 2019 Argument : const psci_power_state_t * 2020 Return : void 2021 2022This is an optional hook that platforms can implement for residency statistics 2023accounting before entering a low power state. The ``pwr_domain_state`` field of 2024``state_info`` (first argument) can be inspected if stat accounting is done 2025differently at CPU level versus higher levels. As an example, if the element at 2026index 0 (CPU power level) in the ``pwr_domain_state`` array indicates a power down 2027state, special hardware logic may be programmed in order to keep track of the 2028residency statistics. For higher levels (array indices > 0), the residency 2029statistics could be tracked in software using PMF. If ``ENABLE_PMF`` is set, the 2030default implementation will use PMF to capture timestamps. 2031 2032Function : plat\_psci\_stat\_accounting\_stop() [optional] 2033~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2034 2035:: 2036 2037 Argument : const psci_power_state_t * 2038 Return : void 2039 2040This is an optional hook that platforms can implement for residency statistics 2041accounting after exiting from a low power state. The ``pwr_domain_state`` field 2042of ``state_info`` (first argument) can be inspected if stat accounting is done 2043differently at CPU level versus higher levels. As an example, if the element at 2044index 0 (CPU power level) in the ``pwr_domain_state`` array indicates a power down 2045state, special hardware logic may be programmed in order to keep track of the 2046residency statistics. For higher levels (array indices > 0), the residency 2047statistics could be tracked in software using PMF. If ``ENABLE_PMF`` is set, the 2048default implementation will use PMF to capture timestamps. 2049 2050Function : plat\_psci\_stat\_get\_residency() [optional] 2051~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2052 2053:: 2054 2055 Argument : unsigned int, const psci_power_state_t *, int 2056 Return : u_register_t 2057 2058This is an optional interface that is is invoked after resuming from a low power 2059state and provides the time spent resident in that low power state by the power 2060domain at a particular power domain level. When a CPU wakes up from suspend, 2061all its parent power domain levels are also woken up. The generic PSCI code 2062invokes this function for each parent power domain that is resumed and it 2063identified by the ``lvl`` (first argument) parameter. The ``state_info`` (second 2064argument) describes the low power state that the power domain has resumed from. 2065The current CPU is the first CPU in the power domain to resume from the low 2066power state and the ``last_cpu_idx`` (third parameter) is the index of the last 2067CPU in the power domain to suspend and may be needed to calculate the residency 2068for that power domain. 2069 2070Function : plat\_get\_target\_pwr\_state() [optional] 2071~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2072 2073:: 2074 2075 Argument : unsigned int, const plat_local_state_t *, unsigned int 2076 Return : plat_local_state_t 2077 2078The PSCI generic code uses this function to let the platform participate in 2079state coordination during a power management operation. The function is passed 2080a pointer to an array of platform specific local power state ``states`` (second 2081argument) which contains the requested power state for each CPU at a particular 2082power domain level ``lvl`` (first argument) within the power domain. The function 2083is expected to traverse this array of upto ``ncpus`` (third argument) and return 2084a coordinated target power state by the comparing all the requested power 2085states. The target power state should not be deeper than any of the requested 2086power states. 2087 2088A weak definition of this API is provided by default wherein it assumes 2089that the platform assigns a local state value in order of increasing depth 2090of the power state i.e. for two power states X & Y, if X < Y 2091then X represents a shallower power state than Y. As a result, the 2092coordinated target local power state for a power domain will be the minimum 2093of the requested local power state values. 2094 2095Function : plat\_get\_power\_domain\_tree\_desc() [mandatory] 2096~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2097 2098:: 2099 2100 Argument : void 2101 Return : const unsigned char * 2102 2103This function returns a pointer to the byte array containing the power domain 2104topology tree description. The format and method to construct this array are 2105described in `Power Domain Topology Design`_. The BL31 PSCI initilization code 2106requires this array to be described by the platform, either statically or 2107dynamically, to initialize the power domain topology tree. In case the array 2108is populated dynamically, then plat\_core\_pos\_by\_mpidr() and 2109plat\_my\_core\_pos() should also be implemented suitably so that the topology 2110tree description matches the CPU indices returned by these APIs. These APIs 2111together form the platform interface for the PSCI topology framework. 2112 2113Function : plat\_setup\_psci\_ops() [mandatory] 2114~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2115 2116:: 2117 2118 Argument : uintptr_t, const plat_psci_ops ** 2119 Return : int 2120 2121This function may execute with the MMU and data caches enabled if the platform 2122port does the necessary initializations in ``bl31_plat_arch_setup()``. It is only 2123called by the primary CPU. 2124 2125This function is called by PSCI initialization code. Its purpose is to let 2126the platform layer know about the warm boot entrypoint through the 2127``sec_entrypoint`` (first argument) and to export handler routines for 2128platform-specific psci power management actions by populating the passed 2129pointer with a pointer to BL31's private ``plat_psci_ops`` structure. 2130 2131A description of each member of this structure is given below. Please refer to 2132the ARM FVP specific implementation of these handlers in 2133`plat/arm/board/fvp/fvp\_pm.c`_ as an example. For each PSCI function that the 2134platform wants to support, the associated operation or operations in this 2135structure must be provided and implemented (Refer section 4 of 2136`Firmware Design`_ for the PSCI API supported in Trusted Firmware). To disable 2137a PSCI function in a platform port, the operation should be removed from this 2138structure instead of providing an empty implementation. 2139 2140plat\_psci\_ops.cpu\_standby() 2141.............................. 2142 2143Perform the platform-specific actions to enter the standby state for a cpu 2144indicated by the passed argument. This provides a fast path for CPU standby 2145wherein overheads of PSCI state management and lock acquistion is avoided. 2146For this handler to be invoked by the PSCI ``CPU_SUSPEND`` API implementation, 2147the suspend state type specified in the ``power-state`` parameter should be 2148STANDBY and the target power domain level specified should be the CPU. The 2149handler should put the CPU into a low power retention state (usually by 2150issuing a wfi instruction) and ensure that it can be woken up from that 2151state by a normal interrupt. The generic code expects the handler to succeed. 2152 2153plat\_psci\_ops.pwr\_domain\_on() 2154................................. 2155 2156Perform the platform specific actions to power on a CPU, specified 2157by the ``MPIDR`` (first argument). The generic code expects the platform to 2158return PSCI\_E\_SUCCESS on success or PSCI\_E\_INTERN\_FAIL for any failure. 2159 2160plat\_psci\_ops.pwr\_domain\_off() 2161.................................. 2162 2163Perform the platform specific actions to prepare to power off the calling CPU 2164and its higher parent power domain levels as indicated by the ``target_state`` 2165(first argument). It is called by the PSCI ``CPU_OFF`` API implementation. 2166 2167The ``target_state`` encodes the platform coordinated target local power states 2168for the CPU power domain and its parent power domain levels. The handler 2169needs to perform power management operation corresponding to the local state 2170at each power level. 2171 2172For this handler, the local power state for the CPU power domain will be a 2173power down state where as it could be either power down, retention or run state 2174for the higher power domain levels depending on the result of state 2175coordination. The generic code expects the handler to succeed. 2176 2177plat\_psci\_ops.pwr\_domain\_suspend\_pwrdown\_early() [optional] 2178................................................................. 2179 2180This optional function may be used as a performance optimization to replace 2181or complement pwr_domain_suspend() on some platforms. Its calling semantics 2182are identical to pwr_domain_suspend(), except the PSCI implementation only 2183calls this function when suspending to a power down state, and it guarantees 2184that data caches are enabled. 2185 2186When HW_ASSISTED_COHERENCY = 0, the PSCI implementation disables data caches 2187before calling pwr_domain_suspend(). If the target_state corresponds to a 2188power down state and it is safe to perform some or all of the platform 2189specific actions in that function with data caches enabled, it may be more 2190efficient to move those actions to this function. When HW_ASSISTED_COHERENCY 2191= 1, data caches remain enabled throughout, and so there is no advantage to 2192moving platform specific actions to this function. 2193 2194plat\_psci\_ops.pwr\_domain\_suspend() 2195...................................... 2196 2197Perform the platform specific actions to prepare to suspend the calling 2198CPU and its higher parent power domain levels as indicated by the 2199``target_state`` (first argument). It is called by the PSCI ``CPU_SUSPEND`` 2200API implementation. 2201 2202The ``target_state`` has a similar meaning as described in 2203the ``pwr_domain_off()`` operation. It encodes the platform coordinated 2204target local power states for the CPU power domain and its parent 2205power domain levels. The handler needs to perform power management operation 2206corresponding to the local state at each power level. The generic code 2207expects the handler to succeed. 2208 2209The difference between turning a power domain off versus suspending it is that 2210in the former case, the power domain is expected to re-initialize its state 2211when it is next powered on (see ``pwr_domain_on_finish()``). In the latter 2212case, the power domain is expected to save enough state so that it can resume 2213execution by restoring this state when its powered on (see 2214``pwr_domain_suspend_finish()``). 2215 2216When suspending a core, the platform can also choose to power off the GICv3 2217Redistributor and ITS through an implementation-defined sequence. To achieve 2218this safely, the ITS context must be saved first. The architectural part is 2219implemented by the ``gicv3_its_save_disable()`` helper, but most of the needed 2220sequence is implementation defined and it is therefore the responsibility of 2221the platform code to implement the necessary sequence. Then the GIC 2222Redistributor context can be saved using the ``gicv3_rdistif_save()`` helper. 2223Powering off the Redistributor requires the implementation to support it and it 2224is the responsibility of the platform code to execute the right implementation 2225defined sequence. 2226 2227When a system suspend is requested, the platform can also make use of the 2228``gicv3_distif_save()`` helper to save the context of the GIC Distributor after 2229it has saved the context of the Redistributors and ITS of all the cores in the 2230system. The context of the Distributor can be large and may require it to be 2231allocated in a special area if it cannot fit in the platform's global static 2232data, for example in DRAM. The Distributor can then be powered down using an 2233implementation-defined sequence. 2234 2235plat\_psci\_ops.pwr\_domain\_pwr\_down\_wfi() 2236............................................. 2237 2238This is an optional function and, if implemented, is expected to perform 2239platform specific actions including the ``wfi`` invocation which allows the 2240CPU to powerdown. Since this function is invoked outside the PSCI locks, 2241the actions performed in this hook must be local to the CPU or the platform 2242must ensure that races between multiple CPUs cannot occur. 2243 2244The ``target_state`` has a similar meaning as described in the ``pwr_domain_off()`` 2245operation and it encodes the platform coordinated target local power states for 2246the CPU power domain and its parent power domain levels. This function must 2247not return back to the caller. 2248 2249If this function is not implemented by the platform, PSCI generic 2250implementation invokes ``psci_power_down_wfi()`` for power down. 2251 2252plat\_psci\_ops.pwr\_domain\_on\_finish() 2253......................................... 2254 2255This function is called by the PSCI implementation after the calling CPU is 2256powered on and released from reset in response to an earlier PSCI ``CPU_ON`` call. 2257It performs the platform-specific setup required to initialize enough state for 2258this CPU to enter the normal world and also provide secure runtime firmware 2259services. 2260 2261The ``target_state`` (first argument) is the prior state of the power domains 2262immediately before the CPU was turned on. It indicates which power domains 2263above the CPU might require initialization due to having previously been in 2264low power states. The generic code expects the handler to succeed. 2265 2266plat\_psci\_ops.pwr\_domain\_suspend\_finish() 2267.............................................. 2268 2269This function is called by the PSCI implementation after the calling CPU is 2270powered on and released from reset in response to an asynchronous wakeup 2271event, for example a timer interrupt that was programmed by the CPU during the 2272``CPU_SUSPEND`` call or ``SYSTEM_SUSPEND`` call. It performs the platform-specific 2273setup required to restore the saved state for this CPU to resume execution 2274in the normal world and also provide secure runtime firmware services. 2275 2276The ``target_state`` (first argument) has a similar meaning as described in 2277the ``pwr_domain_on_finish()`` operation. The generic code expects the platform 2278to succeed. 2279 2280If the Distributor, Redistributors or ITS have been powered off as part of a 2281suspend, their context must be restored in this function in the reverse order 2282to how they were saved during suspend sequence. 2283 2284plat\_psci\_ops.system\_off() 2285............................. 2286 2287This function is called by PSCI implementation in response to a ``SYSTEM_OFF`` 2288call. It performs the platform-specific system poweroff sequence after 2289notifying the Secure Payload Dispatcher. 2290 2291plat\_psci\_ops.system\_reset() 2292............................... 2293 2294This function is called by PSCI implementation in response to a ``SYSTEM_RESET`` 2295call. It performs the platform-specific system reset sequence after 2296notifying the Secure Payload Dispatcher. 2297 2298plat\_psci\_ops.validate\_power\_state() 2299........................................ 2300 2301This function is called by the PSCI implementation during the ``CPU_SUSPEND`` 2302call to validate the ``power_state`` parameter of the PSCI API and if valid, 2303populate it in ``req_state`` (second argument) array as power domain level 2304specific local states. If the ``power_state`` is invalid, the platform must 2305return PSCI\_E\_INVALID\_PARAMS as error, which is propagated back to the 2306normal world PSCI client. 2307 2308plat\_psci\_ops.validate\_ns\_entrypoint() 2309.......................................... 2310 2311This function is called by the PSCI implementation during the ``CPU_SUSPEND``, 2312``SYSTEM_SUSPEND`` and ``CPU_ON`` calls to validate the non-secure ``entry_point`` 2313parameter passed by the normal world. If the ``entry_point`` is invalid, 2314the platform must return PSCI\_E\_INVALID\_ADDRESS as error, which is 2315propagated back to the normal world PSCI client. 2316 2317plat\_psci\_ops.get\_sys\_suspend\_power\_state() 2318................................................. 2319 2320This function is called by the PSCI implementation during the ``SYSTEM_SUSPEND`` 2321call to get the ``req_state`` parameter from platform which encodes the power 2322domain level specific local states to suspend to system affinity level. The 2323``req_state`` will be utilized to do the PSCI state coordination and 2324``pwr_domain_suspend()`` will be invoked with the coordinated target state to 2325enter system suspend. 2326 2327plat\_psci\_ops.get\_pwr\_lvl\_state\_idx() 2328........................................... 2329 2330This is an optional function and, if implemented, is invoked by the PSCI 2331implementation to convert the ``local_state`` (first argument) at a specified 2332``pwr_lvl`` (second argument) to an index between 0 and 2333``PLAT_MAX_PWR_LVL_STATES`` - 1. This function is only needed if the platform 2334supports more than two local power states at each power domain level, that is 2335``PLAT_MAX_PWR_LVL_STATES`` is greater than 2, and needs to account for these 2336local power states. 2337 2338plat\_psci\_ops.translate\_power\_state\_by\_mpidr() 2339.................................................... 2340 2341This is an optional function and, if implemented, verifies the ``power_state`` 2342(second argument) parameter of the PSCI API corresponding to a target power 2343domain. The target power domain is identified by using both ``MPIDR`` (first 2344argument) and the power domain level encoded in ``power_state``. The power domain 2345level specific local states are to be extracted from ``power_state`` and be 2346populated in the ``output_state`` (third argument) array. The functionality 2347is similar to the ``validate_power_state`` function described above and is 2348envisaged to be used in case the validity of ``power_state`` depend on the 2349targeted power domain. If the ``power_state`` is invalid for the targeted power 2350domain, the platform must return PSCI\_E\_INVALID\_PARAMS as error. If this 2351function is not implemented, then the generic implementation relies on 2352``validate_power_state`` function to translate the ``power_state``. 2353 2354This function can also be used in case the platform wants to support local 2355power state encoding for ``power_state`` parameter of PSCI\_STAT\_COUNT/RESIDENCY 2356APIs as described in Section 5.18 of `PSCI`_. 2357 2358plat\_psci\_ops.get\_node\_hw\_state() 2359...................................... 2360 2361This is an optional function. If implemented this function is intended to return 2362the power state of a node (identified by the first parameter, the ``MPIDR``) in 2363the power domain topology (identified by the second parameter, ``power_level``), 2364as retrieved from a power controller or equivalent component on the platform. 2365Upon successful completion, the implementation must map and return the final 2366status among ``HW_ON``, ``HW_OFF`` or ``HW_STANDBY``. Upon encountering failures, it 2367must return either ``PSCI_E_INVALID_PARAMS`` or ``PSCI_E_NOT_SUPPORTED`` as 2368appropriate. 2369 2370Implementations are not expected to handle ``power_levels`` greater than 2371``PLAT_MAX_PWR_LVL``. 2372 2373plat\_psci\_ops.system\_reset2() 2374................................ 2375 2376This is an optional function. If implemented this function is 2377called during the ``SYSTEM_RESET2`` call to perform a reset 2378based on the first parameter ``reset_type`` as specified in 2379`PSCI`_. The parameter ``cookie`` can be used to pass additional 2380reset information. If the ``reset_type`` is not supported, the 2381function must return ``PSCI_E_NOT_SUPPORTED``. For architectural 2382resets, all failures must return ``PSCI_E_INVALID_PARAMETERS`` 2383and vendor reset can return other PSCI error codes as defined 2384in `PSCI`_. On success this function will not return. 2385 2386plat\_psci\_ops.write\_mem\_protect() 2387.................................... 2388 2389This is an optional function. If implemented it enables or disables the 2390``MEM_PROTECT`` functionality based on the value of ``val``. 2391A non-zero value enables ``MEM_PROTECT`` and a value of zero 2392disables it. Upon encountering failures it must return a negative value 2393and on success it must return 0. 2394 2395plat\_psci\_ops.read\_mem\_protect() 2396..................................... 2397 2398This is an optional function. If implemented it returns the current 2399state of ``MEM_PROTECT`` via the ``val`` parameter. Upon encountering 2400failures it must return a negative value and on success it must 2401return 0. 2402 2403plat\_psci\_ops.mem\_protect\_chk() 2404................................... 2405 2406This is an optional function. If implemented it checks if a memory 2407region defined by a base address ``base`` and with a size of ``length`` 2408bytes is protected by ``MEM_PROTECT``. If the region is protected 2409then it must return 0, otherwise it must return a negative number. 2410 2411Interrupt Management framework (in BL31) 2412---------------------------------------- 2413 2414BL31 implements an Interrupt Management Framework (IMF) to manage interrupts 2415generated in either security state and targeted to EL1 or EL2 in the non-secure 2416state or EL3/S-EL1 in the secure state. The design of this framework is 2417described in the `IMF Design Guide`_ 2418 2419A platform should export the following APIs to support the IMF. The following 2420text briefly describes each api and its implementation in ARM standard 2421platforms. The API implementation depends upon the type of interrupt controller 2422present in the platform. ARM standard platform layer supports both 2423`ARM Generic Interrupt Controller version 2.0 (GICv2)`_ 2424and `3.0 (GICv3)`_. Juno builds the ARM 2425Standard layer to use GICv2 and the FVP can be configured to use either GICv2 or 2426GICv3 depending on the build flag ``FVP_USE_GIC_DRIVER`` (See FVP platform 2427specific build options in `User Guide`_ for more details). 2428 2429See also: `Interrupt Controller Abstraction APIs`__. 2430 2431.. __: platform-interrupt-controller-API.rst 2432 2433Function : plat\_interrupt\_type\_to\_line() [mandatory] 2434~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2435 2436:: 2437 2438 Argument : uint32_t, uint32_t 2439 Return : uint32_t 2440 2441The ARM processor signals an interrupt exception either through the IRQ or FIQ 2442interrupt line. The specific line that is signaled depends on how the interrupt 2443controller (IC) reports different interrupt types from an execution context in 2444either security state. The IMF uses this API to determine which interrupt line 2445the platform IC uses to signal each type of interrupt supported by the framework 2446from a given security state. This API must be invoked at EL3. 2447 2448The first parameter will be one of the ``INTR_TYPE_*`` values (see 2449`IMF Design Guide`_) indicating the target type of the interrupt, the second parameter is the 2450security state of the originating execution context. The return result is the 2451bit position in the ``SCR_EL3`` register of the respective interrupt trap: IRQ=1, 2452FIQ=2. 2453 2454In the case of ARM standard platforms using GICv2, S-EL1 interrupts are 2455configured as FIQs and Non-secure interrupts as IRQs from either security 2456state. 2457 2458In the case of ARM standard platforms using GICv3, the interrupt line to be 2459configured depends on the security state of the execution context when the 2460interrupt is signalled and are as follows: 2461 2462- The S-EL1 interrupts are signaled as IRQ in S-EL0/1 context and as FIQ in 2463 NS-EL0/1/2 context. 2464- The Non secure interrupts are signaled as FIQ in S-EL0/1 context and as IRQ 2465 in the NS-EL0/1/2 context. 2466- The EL3 interrupts are signaled as FIQ in both S-EL0/1 and NS-EL0/1/2 2467 context. 2468 2469Function : plat\_ic\_get\_pending\_interrupt\_type() [mandatory] 2470~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2471 2472:: 2473 2474 Argument : void 2475 Return : uint32_t 2476 2477This API returns the type of the highest priority pending interrupt at the 2478platform IC. The IMF uses the interrupt type to retrieve the corresponding 2479handler function. ``INTR_TYPE_INVAL`` is returned when there is no interrupt 2480pending. The valid interrupt types that can be returned are ``INTR_TYPE_EL3``, 2481``INTR_TYPE_S_EL1`` and ``INTR_TYPE_NS``. This API must be invoked at EL3. 2482 2483In the case of ARM standard platforms using GICv2, the *Highest Priority 2484Pending Interrupt Register* (``GICC_HPPIR``) is read to determine the id of 2485the pending interrupt. The type of interrupt depends upon the id value as 2486follows. 2487 2488#. id < 1022 is reported as a S-EL1 interrupt 2489#. id = 1022 is reported as a Non-secure interrupt. 2490#. id = 1023 is reported as an invalid interrupt type. 2491 2492In the case of ARM standard platforms using GICv3, the system register 2493``ICC_HPPIR0_EL1``, *Highest Priority Pending group 0 Interrupt Register*, 2494is read to determine the id of the pending interrupt. The type of interrupt 2495depends upon the id value as follows. 2496 2497#. id = ``PENDING_G1S_INTID`` (1020) is reported as a S-EL1 interrupt 2498#. id = ``PENDING_G1NS_INTID`` (1021) is reported as a Non-secure interrupt. 2499#. id = ``GIC_SPURIOUS_INTERRUPT`` (1023) is reported as an invalid interrupt type. 2500#. All other interrupt id's are reported as EL3 interrupt. 2501 2502Function : plat\_ic\_get\_pending\_interrupt\_id() [mandatory] 2503~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2504 2505:: 2506 2507 Argument : void 2508 Return : uint32_t 2509 2510This API returns the id of the highest priority pending interrupt at the 2511platform IC. ``INTR_ID_UNAVAILABLE`` is returned when there is no interrupt 2512pending. 2513 2514In the case of ARM standard platforms using GICv2, the *Highest Priority 2515Pending Interrupt Register* (``GICC_HPPIR``) is read to determine the id of the 2516pending interrupt. The id that is returned by API depends upon the value of 2517the id read from the interrupt controller as follows. 2518 2519#. id < 1022. id is returned as is. 2520#. id = 1022. The *Aliased Highest Priority Pending Interrupt Register* 2521 (``GICC_AHPPIR``) is read to determine the id of the non-secure interrupt. 2522 This id is returned by the API. 2523#. id = 1023. ``INTR_ID_UNAVAILABLE`` is returned. 2524 2525In the case of ARM standard platforms using GICv3, if the API is invoked from 2526EL3, the system register ``ICC_HPPIR0_EL1``, *Highest Priority Pending Interrupt 2527group 0 Register*, is read to determine the id of the pending interrupt. The id 2528that is returned by API depends upon the value of the id read from the 2529interrupt controller as follows. 2530 2531#. id < ``PENDING_G1S_INTID`` (1020). id is returned as is. 2532#. id = ``PENDING_G1S_INTID`` (1020) or ``PENDING_G1NS_INTID`` (1021). The system 2533 register ``ICC_HPPIR1_EL1``, *Highest Priority Pending Interrupt group 1 2534 Register* is read to determine the id of the group 1 interrupt. This id 2535 is returned by the API as long as it is a valid interrupt id 2536#. If the id is any of the special interrupt identifiers, 2537 ``INTR_ID_UNAVAILABLE`` is returned. 2538 2539When the API invoked from S-EL1 for GICv3 systems, the id read from system 2540register ``ICC_HPPIR1_EL1``, *Highest Priority Pending group 1 Interrupt 2541Register*, is returned if is not equal to GIC\_SPURIOUS\_INTERRUPT (1023) else 2542``INTR_ID_UNAVAILABLE`` is returned. 2543 2544Function : plat\_ic\_acknowledge\_interrupt() [mandatory] 2545~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2546 2547:: 2548 2549 Argument : void 2550 Return : uint32_t 2551 2552This API is used by the CPU to indicate to the platform IC that processing of 2553the highest pending interrupt has begun. It should return the raw, unmodified 2554value obtained from the interrupt controller when acknowledging an interrupt. 2555The actual interrupt number shall be extracted from this raw value using the API 2556`plat_ic_get_interrupt_id()`__. 2557 2558.. __: platform-interrupt-controller-API.rst#function-unsigned-int-plat-ic-get-interrupt-id-unsigned-int-raw-optional 2559 2560This function in ARM standard platforms using GICv2, reads the *Interrupt 2561Acknowledge Register* (``GICC_IAR``). This changes the state of the highest 2562priority pending interrupt from pending to active in the interrupt controller. 2563It returns the value read from the ``GICC_IAR``, unmodified. 2564 2565In the case of ARM standard platforms using GICv3, if the API is invoked 2566from EL3, the function reads the system register ``ICC_IAR0_EL1``, *Interrupt 2567Acknowledge Register group 0*. If the API is invoked from S-EL1, the function 2568reads the system register ``ICC_IAR1_EL1``, *Interrupt Acknowledge Register 2569group 1*. The read changes the state of the highest pending interrupt from 2570pending to active in the interrupt controller. The value read is returned 2571unmodified. 2572 2573The TSP uses this API to start processing of the secure physical timer 2574interrupt. 2575 2576Function : plat\_ic\_end\_of\_interrupt() [mandatory] 2577~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2578 2579:: 2580 2581 Argument : uint32_t 2582 Return : void 2583 2584This API is used by the CPU to indicate to the platform IC that processing of 2585the interrupt corresponding to the id (passed as the parameter) has 2586finished. The id should be the same as the id returned by the 2587``plat_ic_acknowledge_interrupt()`` API. 2588 2589ARM standard platforms write the id to the *End of Interrupt Register* 2590(``GICC_EOIR``) in case of GICv2, and to ``ICC_EOIR0_EL1`` or ``ICC_EOIR1_EL1`` 2591system register in case of GICv3 depending on where the API is invoked from, 2592EL3 or S-EL1. This deactivates the corresponding interrupt in the interrupt 2593controller. 2594 2595The TSP uses this API to finish processing of the secure physical timer 2596interrupt. 2597 2598Function : plat\_ic\_get\_interrupt\_type() [mandatory] 2599~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2600 2601:: 2602 2603 Argument : uint32_t 2604 Return : uint32_t 2605 2606This API returns the type of the interrupt id passed as the parameter. 2607``INTR_TYPE_INVAL`` is returned if the id is invalid. If the id is valid, a valid 2608interrupt type (one of ``INTR_TYPE_EL3``, ``INTR_TYPE_S_EL1`` and ``INTR_TYPE_NS``) is 2609returned depending upon how the interrupt has been configured by the platform 2610IC. This API must be invoked at EL3. 2611 2612ARM standard platforms using GICv2 configures S-EL1 interrupts as Group0 interrupts 2613and Non-secure interrupts as Group1 interrupts. It reads the group value 2614corresponding to the interrupt id from the relevant *Interrupt Group Register* 2615(``GICD_IGROUPRn``). It uses the group value to determine the type of interrupt. 2616 2617In the case of ARM standard platforms using GICv3, both the *Interrupt Group 2618Register* (``GICD_IGROUPRn``) and *Interrupt Group Modifier Register* 2619(``GICD_IGRPMODRn``) is read to figure out whether the interrupt is configured 2620as Group 0 secure interrupt, Group 1 secure interrupt or Group 1 NS interrupt. 2621 2622Crash Reporting mechanism (in BL31) 2623----------------------------------- 2624 2625BL31 implements a crash reporting mechanism which prints the various registers 2626of the CPU to enable quick crash analysis and debugging. It requires that a 2627console is designated as the crash console by the platform which will be used to 2628print the register dump. 2629 2630The following functions must be implemented by the platform if it wants crash 2631reporting mechanism in BL31. The functions are implemented in assembly so that 2632they can be invoked without a C Runtime stack. 2633 2634Function : plat\_crash\_console\_init 2635~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2636 2637:: 2638 2639 Argument : void 2640 Return : int 2641 2642This API is used by the crash reporting mechanism to initialize the crash 2643console. It must only use the general purpose registers x0 to x4 to do the 2644initialization and returns 1 on success. 2645 2646Function : plat\_crash\_console\_putc 2647~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2648 2649:: 2650 2651 Argument : int 2652 Return : int 2653 2654This API is used by the crash reporting mechanism to print a character on the 2655designated crash console. It must only use general purpose registers x1 and 2656x2 to do its work. The parameter and the return value are in general purpose 2657register x0. 2658 2659Function : plat\_crash\_console\_flush 2660~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2661 2662:: 2663 2664 Argument : void 2665 Return : int 2666 2667This API is used by the crash reporting mechanism to force write of all buffered 2668data on the designated crash console. It should only use general purpose 2669registers x0 and x1 to do its work. The return value is 0 on successful 2670completion; otherwise the return value is -1. 2671 2672Build flags 2673----------- 2674 2675- **ENABLE\_PLAT\_COMPAT** 2676 All the platforms ports conforming to this API specification should define 2677 the build flag ``ENABLE_PLAT_COMPAT`` to 0 as the compatibility layer should 2678 be disabled. For more details on compatibility layer, refer 2679 `Migration Guide`_. 2680 2681There are some build flags which can be defined by the platform to control 2682inclusion or exclusion of certain BL stages from the FIP image. These flags 2683need to be defined in the platform makefile which will get included by the 2684build system. 2685 2686- **NEED\_BL33** 2687 By default, this flag is defined ``yes`` by the build system and ``BL33`` 2688 build option should be supplied as a build option. The platform has the 2689 option of excluding the BL33 image in the ``fip`` image by defining this flag 2690 to ``no``. If any of the options ``EL3_PAYLOAD_BASE`` or ``PRELOADED_BL33_BASE`` 2691 are used, this flag will be set to ``no`` automatically. 2692 2693C Library 2694--------- 2695 2696To avoid subtle toolchain behavioral dependencies, the header files provided 2697by the compiler are not used. The software is built with the ``-nostdinc`` flag 2698to ensure no headers are included from the toolchain inadvertently. Instead the 2699required headers are included in the ARM Trusted Firmware source tree. The 2700library only contains those C library definitions required by the local 2701implementation. If more functionality is required, the needed library functions 2702will need to be added to the local implementation. 2703 2704Versions of `FreeBSD`_ headers can be found in ``include/lib/stdlib``. Some of 2705these headers have been cut down in order to simplify the implementation. In 2706order to minimize changes to the header files, the `FreeBSD`_ layout has been 2707maintained. The generic C library definitions can be found in 2708``include/lib/stdlib`` with more system and machine specific declarations in 2709``include/lib/stdlib/sys`` and ``include/lib/stdlib/machine``. 2710 2711The local C library implementations can be found in ``lib/stdlib``. In order to 2712extend the C library these files may need to be modified. It is recommended to 2713use a release version of `FreeBSD`_ as a starting point. 2714 2715The C library header files in the `FreeBSD`_ source tree are located in the 2716``include`` and ``sys/sys`` directories. `FreeBSD`_ machine specific definitions 2717can be found in the ``sys/<machine-type>`` directories. These files define things 2718like 'the size of a pointer' and 'the range of an integer'. Since an AArch64 2719port for `FreeBSD`_ does not yet exist, the machine specific definitions are 2720based on existing machine types with similar properties (for example SPARC64). 2721 2722Where possible, C library function implementations were taken from `FreeBSD`_ 2723as found in the ``lib/libc`` directory. 2724 2725A copy of the `FreeBSD`_ sources can be downloaded with ``git``. 2726 2727:: 2728 2729 git clone git://github.com/freebsd/freebsd.git -b origin/release/9.2.0 2730 2731Storage abstraction layer 2732------------------------- 2733 2734In order to improve platform independence and portability an storage abstraction 2735layer is used to load data from non-volatile platform storage. 2736 2737Each platform should register devices and their drivers via the Storage layer. 2738These drivers then need to be initialized by bootloader phases as 2739required in their respective ``blx_platform_setup()`` functions. Currently 2740storage access is only required by BL1 and BL2 phases. The ``load_image()`` 2741function uses the storage layer to access non-volatile platform storage. 2742 2743It is mandatory to implement at least one storage driver. For the ARM 2744development platforms the Firmware Image Package (FIP) driver is provided as 2745the default means to load data from storage (see the "Firmware Image Package" 2746section in the `User Guide`_). The storage layer is described in the header file 2747``include/drivers/io/io_storage.h``. The implementation of the common library 2748is in ``drivers/io/io_storage.c`` and the driver files are located in 2749``drivers/io/``. 2750 2751Each IO driver must provide ``io_dev_*`` structures, as described in 2752``drivers/io/io_driver.h``. These are returned via a mandatory registration 2753function that is called on platform initialization. The semi-hosting driver 2754implementation in ``io_semihosting.c`` can be used as an example. 2755 2756The Storage layer provides mechanisms to initialize storage devices before 2757IO operations are called. The basic operations supported by the layer 2758include ``open()``, ``close()``, ``read()``, ``write()``, ``size()`` and ``seek()``. 2759Drivers do not have to implement all operations, but each platform must 2760provide at least one driver for a device capable of supporting generic 2761operations such as loading a bootloader image. 2762 2763The current implementation only allows for known images to be loaded by the 2764firmware. These images are specified by using their identifiers, as defined in 2765[include/plat/common/platform\_def.h] (or a separate header file included from 2766there). The platform layer (``plat_get_image_source()``) then returns a reference 2767to a device and a driver-specific ``spec`` which will be understood by the driver 2768to allow access to the image data. 2769 2770The layer is designed in such a way that is it possible to chain drivers with 2771other drivers. For example, file-system drivers may be implemented on top of 2772physical block devices, both represented by IO devices with corresponding 2773drivers. In such a case, the file-system "binding" with the block device may 2774be deferred until the file-system device is initialised. 2775 2776The abstraction currently depends on structures being statically allocated 2777by the drivers and callers, as the system does not yet provide a means of 2778dynamically allocating memory. This may also have the affect of limiting the 2779amount of open resources per driver. 2780 2781-------------- 2782 2783*Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.* 2784 2785.. _Migration Guide: platform-migration-guide.rst 2786.. _include/plat/common/platform.h: ../include/plat/common/platform.h 2787.. _include/plat/arm/common/plat\_arm.h: ../include/plat/arm/common/plat_arm.h%5D 2788.. _User Guide: user-guide.rst 2789.. _include/plat/common/common\_def.h: ../include/plat/common/common_def.h 2790.. _include/plat/arm/common/arm\_def.h: ../include/plat/arm/common/arm_def.h 2791.. _plat/common/aarch64/platform\_mp\_stack.S: ../plat/common/aarch64/platform_mp_stack.S 2792.. _plat/common/aarch64/platform\_up\_stack.S: ../plat/common/aarch64/platform_up_stack.S 2793.. _For example, define the build flag in platform.mk: PLAT_PL061_MAX_GPIOS%20:=%20160 2794.. _Power Domain Topology Design: psci-pd-tree.rst 2795.. _include/common/bl\_common.h: ../include/common/bl_common.h 2796.. _include/lib/aarch32/arch.h: ../include/lib/aarch32/arch.h 2797.. _Firmware Design: firmware-design.rst 2798.. _PSCI: http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf 2799.. _plat/arm/board/fvp/fvp\_pm.c: ../plat/arm/board/fvp/fvp_pm.c 2800.. _IMF Design Guide: interrupt-framework-design.rst 2801.. _ARM Generic Interrupt Controller version 2.0 (GICv2): http://infocenter.arm.com/help/topic/com.arm.doc.ihi0048b/index.html 2802.. _3.0 (GICv3): http://infocenter.arm.com/help/topic/com.arm.doc.ihi0069b/index.html 2803.. _FreeBSD: http://www.freebsd.org 2804