1 // SPDX-License-Identifier: BSD-3-Clause 2 /* 3 * Copyright (c) 2018-2023, STMicroelectronics 4 */ 5 6 #include <assert.h> 7 #include <drivers/clk.h> 8 #include <drivers/clk_dt.h> 9 #include <drivers/rstctrl.h> 10 #include <io.h> 11 #include <kernel/delay.h> 12 #include <kernel/dt.h> 13 #include <kernel/dt_driver.h> 14 #include <kernel/boot.h> 15 #include <kernel/panic.h> 16 #include <kernel/pm.h> 17 #include <kernel/thread.h> 18 #include <libfdt.h> 19 #include <mm/core_memprot.h> 20 #include <rng_support.h> 21 #include <stdbool.h> 22 #include <stm32_util.h> 23 #include <string.h> 24 #include <tee/tee_cryp_utl.h> 25 26 #define RNG_CR U(0x00) 27 #define RNG_SR U(0x04) 28 #define RNG_DR U(0x08) 29 30 #define RNG_CR_RNGEN BIT(2) 31 #define RNG_CR_IE BIT(3) 32 #define RNG_CR_CED BIT(5) 33 #define RNG_CR_CLKDIV GENMASK_32(19, 16) 34 #define RNG_CR_CLKDIV_SHIFT U(16) 35 #define RNG_CR_CONDRST BIT(30) 36 37 #define RNG_SR_DRDY BIT(0) 38 #define RNG_SR_CECS BIT(1) 39 #define RNG_SR_SECS BIT(2) 40 #define RNG_SR_CEIS BIT(5) 41 #define RNG_SR_SEIS BIT(6) 42 43 #if TRACE_LEVEL > TRACE_DEBUG 44 #define RNG_READY_TIMEOUT_US U(100000) 45 #else 46 #define RNG_READY_TIMEOUT_US U(10000) 47 #endif 48 #define RNG_RESET_TIMEOUT_US U(1000) 49 50 #define RNG_FIFO_BYTE_DEPTH U(16) 51 52 #define RNG_NIST_CONFIG_A U(0x0F00D00) 53 #define RNG_NIST_CONFIG_B U(0x1801000) 54 #define RNG_NIST_CONFIG_MASK GENMASK_32(25, 8) 55 56 #define RNG_MAX_NOISE_CLK_FREQ U(3000000) 57 58 struct stm32_rng_driver_data { 59 bool has_cond_reset; 60 }; 61 62 struct stm32_rng_instance { 63 struct io_pa_va base; 64 struct clk *clock; 65 struct rstctrl *rstctrl; 66 const struct stm32_rng_driver_data *ddata; 67 unsigned int lock; 68 bool release_post_boot; 69 bool clock_error; 70 bool error_conceal; 71 uint64_t error_to_ref; 72 }; 73 74 /* Expect at most a single RNG instance */ 75 static struct stm32_rng_instance *stm32_rng; 76 77 static vaddr_t get_base(void) 78 { 79 assert(stm32_rng); 80 81 return io_pa_or_va(&stm32_rng->base, 1); 82 } 83 84 /* 85 * Extracts from the STM32 RNG specification when RNG supports CONDRST. 86 * 87 * When a noise source (or seed) error occurs, the RNG stops generating 88 * random numbers and sets to “1” both SEIS and SECS bits to indicate 89 * that a seed error occurred. (...) 90 * 91 * 1. Software reset by writing CONDRST at 1 and at 0 (see bitfield 92 * description for details). This step is needed only if SECS is set. 93 * Indeed, when SEIS is set and SECS is cleared it means RNG performed 94 * the reset automatically (auto-reset). 95 * 2. If SECS was set in step 1 (no auto-reset) wait for CONDRST 96 * to be cleared in the RNG_CR register, then confirm that SEIS is 97 * cleared in the RNG_SR register. Otherwise just clear SEIS bit in 98 * the RNG_SR register. 99 * 3. If SECS was set in step 1 (no auto-reset) wait for SECS to be 100 * cleared by RNG. The random number generation is now back to normal. 101 */ 102 static void conceal_seed_error_cond_reset(void) 103 { 104 struct stm32_rng_instance *dev = stm32_rng; 105 vaddr_t rng_base = get_base(); 106 107 if (!dev->error_conceal) { 108 uint32_t sr = io_read32(rng_base + RNG_SR); 109 110 if (sr & RNG_SR_SECS) { 111 /* Conceal by resetting the subsystem (step 1.) */ 112 io_setbits32(rng_base + RNG_CR, RNG_CR_CONDRST); 113 io_clrbits32(rng_base + RNG_CR, RNG_CR_CONDRST); 114 115 /* Arm timeout for error_conceal sequence */ 116 dev->error_to_ref = 117 timeout_init_us(RNG_READY_TIMEOUT_US); 118 dev->error_conceal = true; 119 } else { 120 /* RNG auto-reset (step 2.) */ 121 io_clrbits32(rng_base + RNG_SR, RNG_SR_SEIS); 122 } 123 } else { 124 /* Measure time before possible reschedule */ 125 bool timed_out = timeout_elapsed(dev->error_to_ref); 126 127 /* Wait CONDRST is cleared (step 2.) */ 128 if (io_read32(rng_base + RNG_CR) & RNG_CR_CONDRST) { 129 if (timed_out) 130 panic(); 131 132 /* Wait subsystem reset cycle completes */ 133 return; 134 } 135 136 /* Check SEIS is cleared (step 2.) */ 137 if (io_read32(rng_base + RNG_SR) & RNG_SR_SEIS) 138 panic(); 139 140 /* Wait SECS is cleared (step 3.) */ 141 if (io_read32(rng_base + RNG_SR) & RNG_SR_SECS) { 142 if (timed_out) 143 panic(); 144 145 /* Wait subsystem reset cycle completes */ 146 return; 147 } 148 149 dev->error_conceal = false; 150 } 151 } 152 153 /* 154 * Extracts from the STM32 RNG specification, when CONDRST is not supported 155 * 156 * When a noise source (or seed) error occurs, the RNG stops generating 157 * random numbers and sets to “1” both SEIS and SECS bits to indicate 158 * that a seed error occurred. (...) 159 * 160 * The following sequence shall be used to fully recover from a seed 161 * error after the RNG initialization: 162 * 1. Clear the SEIS bit by writing it to “0”. 163 * 2. Read out 12 words from the RNG_DR register, and discard each of 164 * them in order to clean the pipeline. 165 * 3. Confirm that SEIS is still cleared. Random number generation is 166 * back to normal. 167 */ 168 static void conceal_seed_error_sw_reset(void) 169 { 170 vaddr_t rng_base = get_base(); 171 size_t i = 0; 172 173 io_clrbits32(rng_base + RNG_SR, RNG_SR_SEIS); 174 175 for (i = 12; i != 0; i--) 176 (void)io_read32(rng_base + RNG_DR); 177 178 if (io_read32(rng_base + RNG_SR) & RNG_SR_SEIS) 179 panic("RNG noise"); 180 } 181 182 static void conceal_seed_error(void) 183 { 184 if (stm32_rng->ddata->has_cond_reset) 185 conceal_seed_error_cond_reset(); 186 else 187 conceal_seed_error_sw_reset(); 188 } 189 190 static TEE_Result read_available(vaddr_t rng_base, uint8_t *out, size_t *size) 191 { 192 struct stm32_rng_instance *dev = stm32_rng; 193 uint8_t *buf = NULL; 194 size_t req_size = 0; 195 size_t len = 0; 196 197 if (dev->error_conceal || io_read32(rng_base + RNG_SR) & RNG_SR_SEIS) 198 conceal_seed_error(); 199 200 if (!(io_read32(rng_base + RNG_SR) & RNG_SR_DRDY)) { 201 FMSG("RNG not ready"); 202 return TEE_ERROR_NO_DATA; 203 } 204 205 if (io_read32(rng_base + RNG_SR) & RNG_SR_SEIS) { 206 FMSG("RNG noise error"); 207 return TEE_ERROR_NO_DATA; 208 } 209 210 buf = out; 211 req_size = MIN(RNG_FIFO_BYTE_DEPTH, *size); 212 len = req_size; 213 214 /* RNG is ready: read up to 4 32bit words */ 215 while (len) { 216 uint32_t data32 = 0; 217 size_t sz = MIN(len, sizeof(uint32_t)); 218 219 if (!(io_read32(rng_base + RNG_SR) & RNG_SR_DRDY)) 220 break; 221 data32 = io_read32(rng_base + RNG_DR); 222 223 /* Late seed error case: DR being 0 is an error status */ 224 if (!data32) { 225 conceal_seed_error(); 226 return TEE_ERROR_NO_DATA; 227 } 228 229 memcpy(buf, &data32, sz); 230 buf += sz; 231 len -= sz; 232 } 233 234 *size = req_size - len; 235 236 return TEE_SUCCESS; 237 } 238 239 static uint32_t stm32_rng_clock_freq_restrain(void) 240 { 241 struct stm32_rng_instance *dev = stm32_rng; 242 unsigned long clock_rate = 0; 243 uint32_t clock_div = 0; 244 245 clock_rate = clk_get_rate(dev->clock); 246 247 /* 248 * Get the exponent to apply on the CLKDIV field in RNG_CR register 249 * No need to handle the case when clock-div > 0xF as it is physically 250 * impossible 251 */ 252 while ((clock_rate >> clock_div) > RNG_MAX_NOISE_CLK_FREQ) 253 clock_div++; 254 255 DMSG("RNG clk rate : %lu", clk_get_rate(dev->clock) >> clock_div); 256 257 return clock_div; 258 } 259 260 static TEE_Result init_rng(void) 261 { 262 vaddr_t rng_base = get_base(); 263 uint64_t timeout_ref = 0; 264 uint32_t cr_ced_mask = 0; 265 266 if (!stm32_rng->clock_error) 267 cr_ced_mask = RNG_CR_CED; 268 269 /* Clean error indications */ 270 io_write32(rng_base + RNG_SR, 0); 271 272 if (stm32_rng->ddata->has_cond_reset) { 273 uint32_t clock_div = stm32_rng_clock_freq_restrain(); 274 275 /* Update configuration fields */ 276 io_clrsetbits32(rng_base + RNG_CR, RNG_NIST_CONFIG_MASK, 277 RNG_NIST_CONFIG_B | RNG_CR_CONDRST | 278 cr_ced_mask); 279 io_clrsetbits32(rng_base + RNG_CR, RNG_CR_CLKDIV, 280 clock_div << RNG_CR_CLKDIV_SHIFT); 281 282 /* No need to wait for RNG_CR_CONDRST toggle as we enable clk */ 283 io_clrsetbits32(rng_base + RNG_CR, RNG_CR_CONDRST, 284 RNG_CR_RNGEN); 285 } else { 286 io_setbits32(rng_base + RNG_CR, RNG_CR_RNGEN | cr_ced_mask); 287 } 288 289 timeout_ref = timeout_init_us(RNG_READY_TIMEOUT_US); 290 while (!(io_read32(rng_base + RNG_SR) & RNG_SR_DRDY)) 291 if (timeout_elapsed(timeout_ref)) 292 break; 293 294 if (!(io_read32(rng_base + RNG_SR) & RNG_SR_DRDY)) 295 return TEE_ERROR_GENERIC; 296 297 return TEE_SUCCESS; 298 } 299 300 static TEE_Result stm32_rng_read(uint8_t *out, size_t size) 301 { 302 TEE_Result rc = TEE_ERROR_GENERIC; 303 bool burst_timeout = false; 304 uint64_t timeout_ref = 0; 305 uint32_t exceptions = 0; 306 uint8_t *out_ptr = out; 307 vaddr_t rng_base = 0; 308 size_t out_size = 0; 309 310 if (!stm32_rng) { 311 DMSG("No RNG"); 312 return TEE_ERROR_NOT_SUPPORTED; 313 } 314 315 rc = clk_enable(stm32_rng->clock); 316 if (rc) 317 return rc; 318 319 rng_base = get_base(); 320 321 /* Arm timeout */ 322 timeout_ref = timeout_init_us(RNG_READY_TIMEOUT_US); 323 burst_timeout = false; 324 325 while (out_size < size) { 326 /* Read by chunks of the size the RNG FIFO depth */ 327 size_t sz = size - out_size; 328 329 exceptions = may_spin_lock(&stm32_rng->lock); 330 331 rc = read_available(rng_base, out_ptr, &sz); 332 333 /* Raise timeout only if we failed to get some samples */ 334 assert(!rc || rc == TEE_ERROR_NO_DATA); 335 if (rc) 336 burst_timeout = timeout_elapsed(timeout_ref); 337 338 may_spin_unlock(&stm32_rng->lock, exceptions); 339 340 if (burst_timeout) { 341 rc = TEE_ERROR_GENERIC; 342 goto out; 343 } 344 345 if (!rc) { 346 out_size += sz; 347 out_ptr += sz; 348 /* Re-arm timeout */ 349 timeout_ref = timeout_init_us(RNG_READY_TIMEOUT_US); 350 burst_timeout = false; 351 } 352 } 353 354 out: 355 assert(!rc || rc == TEE_ERROR_GENERIC); 356 clk_disable(stm32_rng->clock); 357 358 return rc; 359 } 360 361 #ifdef CFG_WITH_SOFTWARE_PRNG 362 /* Override weak plat_rng_init with platform handler to seed PRNG */ 363 void plat_rng_init(void) 364 { 365 uint8_t seed[RNG_FIFO_BYTE_DEPTH] = { }; 366 367 if (stm32_rng_read(seed, sizeof(seed))) 368 panic(); 369 370 if (crypto_rng_init(seed, sizeof(seed))) 371 panic(); 372 373 DMSG("PRNG seeded with RNG"); 374 } 375 #else 376 TEE_Result hw_get_random_bytes(void *out, size_t size) 377 { 378 return stm32_rng_read(out, size); 379 } 380 381 void plat_rng_init(void) 382 { 383 } 384 #endif 385 386 static TEE_Result stm32_rng_pm_resume(uint32_t pm_cr) 387 { 388 vaddr_t base = get_base(); 389 390 /* Clean error indications */ 391 io_write32(base + RNG_SR, 0); 392 393 if (stm32_rng->ddata->has_cond_reset) { 394 /* 395 * Correct configuration in bits [29:4] must be set in the same 396 * access that set RNG_CR_CONDRST bit. Else config setting is 397 * not taken into account. 398 */ 399 io_write32(base + RNG_CR, pm_cr | RNG_CR_CONDRST); 400 401 io_clrsetbits32(base + RNG_CR, RNG_CR_CONDRST, RNG_CR_RNGEN); 402 } else { 403 io_write32(base + RNG_CR, RNG_CR_RNGEN | pm_cr); 404 } 405 406 return TEE_SUCCESS; 407 } 408 409 static TEE_Result 410 stm32_rng_pm(enum pm_op op, unsigned int pm_hint __unused, 411 const struct pm_callback_handle *pm_handle __unused) 412 { 413 static uint32_t pm_cr; 414 TEE_Result res = TEE_ERROR_GENERIC; 415 416 assert(stm32_rng && (op == PM_OP_SUSPEND || op == PM_OP_RESUME)); 417 418 res = clk_enable(stm32_rng->clock); 419 if (res) 420 return res; 421 422 if (op == PM_OP_SUSPEND) 423 pm_cr = io_read32(get_base() + RNG_CR); 424 else 425 res = stm32_rng_pm_resume(pm_cr); 426 427 clk_disable(stm32_rng->clock); 428 429 return res; 430 } 431 DECLARE_KEEP_PAGER(stm32_rng_pm); 432 433 static TEE_Result stm32_rng_parse_fdt(const void *fdt, int node) 434 { 435 TEE_Result res = TEE_ERROR_GENERIC; 436 struct dt_node_info dt_rng = { }; 437 438 fdt_fill_device_info(fdt, &dt_rng, node); 439 if (dt_rng.reg == DT_INFO_INVALID_REG) 440 return TEE_ERROR_BAD_PARAMETERS; 441 442 stm32_rng->base.pa = dt_rng.reg; 443 stm32_rng->base.va = io_pa_or_va_secure(&stm32_rng->base, 444 dt_rng.reg_size); 445 assert(stm32_rng->base.va); 446 447 res = rstctrl_dt_get_by_index(fdt, node, 0, &stm32_rng->rstctrl); 448 if (res != TEE_SUCCESS && res != TEE_ERROR_ITEM_NOT_FOUND) 449 return res; 450 451 res = clk_dt_get_by_index(fdt, node, 0, &stm32_rng->clock); 452 if (res) 453 return res; 454 455 if (fdt_getprop(fdt, node, "clock-error-detect", NULL)) 456 stm32_rng->clock_error = true; 457 458 /* Release device if not used at runtime or for pm transitions */ 459 stm32_rng->release_post_boot = IS_ENABLED(CFG_WITH_SOFTWARE_PRNG) && 460 !IS_ENABLED(CFG_PM); 461 462 return TEE_SUCCESS; 463 } 464 465 static TEE_Result stm32_rng_probe(const void *fdt, int offs, 466 const void *compat_data __unused) 467 { 468 TEE_Result res = TEE_ERROR_GENERIC; 469 470 /* Expect a single RNG instance */ 471 assert(!stm32_rng); 472 473 stm32_rng = calloc(1, sizeof(*stm32_rng)); 474 if (!stm32_rng) 475 panic(); 476 477 res = stm32_rng_parse_fdt(fdt, offs); 478 if (res) 479 goto err; 480 481 stm32_rng->ddata = compat_data; 482 assert(stm32_rng->ddata); 483 484 res = clk_enable(stm32_rng->clock); 485 if (res) 486 goto err; 487 488 if (stm32_rng->rstctrl && 489 rstctrl_assert_to(stm32_rng->rstctrl, RNG_RESET_TIMEOUT_US)) { 490 res = TEE_ERROR_GENERIC; 491 goto err_clk; 492 } 493 494 if (stm32_rng->rstctrl && 495 rstctrl_deassert_to(stm32_rng->rstctrl, RNG_RESET_TIMEOUT_US)) { 496 res = TEE_ERROR_GENERIC; 497 goto err_clk; 498 } 499 500 res = init_rng(); 501 if (res) 502 goto err_clk; 503 504 clk_disable(stm32_rng->clock); 505 506 if (stm32_rng->release_post_boot) 507 stm32mp_register_non_secure_periph_iomem(stm32_rng->base.pa); 508 else 509 stm32mp_register_secure_periph_iomem(stm32_rng->base.pa); 510 511 register_pm_core_service_cb(stm32_rng_pm, &stm32_rng, "rng-service"); 512 513 return TEE_SUCCESS; 514 515 err_clk: 516 clk_disable(stm32_rng->clock); 517 err: 518 free(stm32_rng); 519 stm32_rng = NULL; 520 521 return res; 522 } 523 524 static const struct stm32_rng_driver_data mp13_data[] = { 525 { .has_cond_reset = true }, 526 }; 527 528 static const struct stm32_rng_driver_data mp15_data[] = { 529 { .has_cond_reset = false }, 530 }; 531 DECLARE_KEEP_PAGER(mp15_data); 532 533 static const struct dt_device_match rng_match_table[] = { 534 { .compatible = "st,stm32-rng", .compat_data = &mp15_data }, 535 { .compatible = "st,stm32mp13-rng", .compat_data = &mp13_data }, 536 { } 537 }; 538 539 DEFINE_DT_DRIVER(stm32_rng_dt_driver) = { 540 .name = "stm32_rng", 541 .match_table = rng_match_table, 542 .probe = stm32_rng_probe, 543 }; 544 545 static TEE_Result stm32_rng_release(void) 546 { 547 if (stm32_rng && stm32_rng->release_post_boot) { 548 DMSG("Release RNG driver"); 549 free(stm32_rng); 550 stm32_rng = NULL; 551 } 552 553 return TEE_SUCCESS; 554 } 555 556 release_init_resource(stm32_rng_release); 557