1// SPDX-License-Identifier: GPL-2.0 2/* 3 * SPI NOR Software Write Protection logic. 4 * 5 * Copyright (C) 2005, Intec Automation Inc. 6 * Copyright (C) 2014, Freescale Semiconductor, Inc. 7 */ 8#include <linux/mtd/mtd.h> 9#include <linux/mtd/spi-nor.h> 10 11#include "core.h" 12 13static u8 spi_nor_get_sr_bp_mask(struct spi_nor *nor) 14{ 15 u8 mask = SR_BP2 | SR_BP1 | SR_BP0; 16 17 if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6) 18 return mask | SR_BP3_BIT6; 19 20 if (nor->flags & SNOR_F_HAS_4BIT_BP) 21 return mask | SR_BP3; 22 23 return mask; 24} 25 26static u8 spi_nor_get_sr_tb_mask(struct spi_nor *nor) 27{ 28 if (nor->flags & SNOR_F_HAS_SR_TB_BIT6) 29 return SR_TB_BIT6; 30 else 31 return SR_TB_BIT5; 32} 33 34static u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor) 35{ 36 unsigned int bp_slots, bp_slots_needed; 37 /* 38 * sector_size will eventually be replaced with the max erase size of 39 * the flash. For now, we need to have that ugly default. 40 */ 41 unsigned int sector_size = nor->info->sector_size ?: SPI_NOR_DEFAULT_SECTOR_SIZE; 42 u64 n_sectors = div_u64(nor->params->size, sector_size); 43 u8 mask = spi_nor_get_sr_bp_mask(nor); 44 45 /* Reserved one for "protect none" and one for "protect all". */ 46 bp_slots = (1 << hweight8(mask)) - 2; 47 bp_slots_needed = ilog2(n_sectors); 48 49 if (bp_slots_needed > bp_slots) 50 return sector_size << (bp_slots_needed - bp_slots); 51 else 52 return sector_size; 53} 54 55static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs, 56 u64 *len) 57{ 58 struct mtd_info *mtd = &nor->mtd; 59 u64 min_prot_len; 60 u8 mask = spi_nor_get_sr_bp_mask(nor); 61 u8 tb_mask = spi_nor_get_sr_tb_mask(nor); 62 u8 bp, val = sr & mask; 63 64 if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6) 65 val = (val & ~SR_BP3_BIT6) | SR_BP3; 66 67 bp = val >> SR_BP_SHIFT; 68 69 if (!bp) { 70 /* No protection */ 71 *ofs = 0; 72 *len = 0; 73 return; 74 } 75 76 min_prot_len = spi_nor_get_min_prot_length_sr(nor); 77 *len = min_prot_len << (bp - 1); 78 79 if (*len > mtd->size) 80 *len = mtd->size; 81 82 if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask) 83 *ofs = 0; 84 else 85 *ofs = mtd->size - *len; 86} 87 88/* 89 * Return true if the entire region is locked (if @locked is true) or unlocked 90 * (if @locked is false); false otherwise. 91 */ 92static bool spi_nor_check_lock_status_sr(struct spi_nor *nor, loff_t ofs, 93 u64 len, u8 sr, bool locked) 94{ 95 loff_t lock_offs, lock_offs_max, offs_max; 96 u64 lock_len; 97 98 if (!len) 99 return true; 100 101 spi_nor_get_locked_range_sr(nor, sr, &lock_offs, &lock_len); 102 103 lock_offs_max = lock_offs + lock_len; 104 offs_max = ofs + len; 105 106 if (locked) 107 /* Requested range is a sub-range of locked range */ 108 return (offs_max <= lock_offs_max) && (ofs >= lock_offs); 109 else 110 /* Requested range does not overlap with locked range */ 111 return (ofs >= lock_offs_max) || (offs_max <= lock_offs); 112} 113 114static bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, u64 len, u8 sr) 115{ 116 return spi_nor_check_lock_status_sr(nor, ofs, len, sr, true); 117} 118 119static bool spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, u64 len, 120 u8 sr) 121{ 122 return spi_nor_check_lock_status_sr(nor, ofs, len, sr, false); 123} 124 125/* 126 * Lock a region of the flash. Compatible with ST Micro and similar flash. 127 * Supports the block protection bits BP{0,1,2}/BP{0,1,2,3} in the status 128 * register 129 * (SR). Does not support these features found in newer SR bitfields: 130 * - SEC: sector/block protect - only handle SEC=0 (block protect) 131 * - CMP: complement protect - only support CMP=0 (range is not complemented) 132 * 133 * Support for the following is provided conditionally for some flash: 134 * - TB: top/bottom protect 135 * 136 * Sample table portion for 8MB flash (Winbond w25q64fw): 137 * 138 * SEC | TB | BP2 | BP1 | BP0 | Prot Length | Protected Portion 139 * -------------------------------------------------------------------------- 140 * X | X | 0 | 0 | 0 | NONE | NONE 141 * 0 | 0 | 0 | 0 | 1 | 128 KB | Upper 1/64 142 * 0 | 0 | 0 | 1 | 0 | 256 KB | Upper 1/32 143 * 0 | 0 | 0 | 1 | 1 | 512 KB | Upper 1/16 144 * 0 | 0 | 1 | 0 | 0 | 1 MB | Upper 1/8 145 * 0 | 0 | 1 | 0 | 1 | 2 MB | Upper 1/4 146 * 0 | 0 | 1 | 1 | 0 | 4 MB | Upper 1/2 147 * X | X | 1 | 1 | 1 | 8 MB | ALL 148 * ------|-------|-------|-------|-------|---------------|------------------- 149 * 0 | 1 | 0 | 0 | 1 | 128 KB | Lower 1/64 150 * 0 | 1 | 0 | 1 | 0 | 256 KB | Lower 1/32 151 * 0 | 1 | 0 | 1 | 1 | 512 KB | Lower 1/16 152 * 0 | 1 | 1 | 0 | 0 | 1 MB | Lower 1/8 153 * 0 | 1 | 1 | 0 | 1 | 2 MB | Lower 1/4 154 * 0 | 1 | 1 | 1 | 0 | 4 MB | Lower 1/2 155 * 156 * Returns negative on errors, 0 on success. 157 */ 158static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len) 159{ 160 struct mtd_info *mtd = &nor->mtd; 161 u64 min_prot_len; 162 int ret, status_old, status_new; 163 u8 mask = spi_nor_get_sr_bp_mask(nor); 164 u8 tb_mask = spi_nor_get_sr_tb_mask(nor); 165 u8 pow, val; 166 loff_t lock_len; 167 bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB; 168 bool use_top; 169 170 ret = spi_nor_read_sr(nor, nor->bouncebuf); 171 if (ret) 172 return ret; 173 174 status_old = nor->bouncebuf[0]; 175 176 /* If nothing in our range is unlocked, we don't need to do anything */ 177 if (spi_nor_is_locked_sr(nor, ofs, len, status_old)) 178 return 0; 179 180 /* If anything below us is unlocked, we can't use 'bottom' protection */ 181 if (!spi_nor_is_locked_sr(nor, 0, ofs, status_old)) 182 can_be_bottom = false; 183 184 /* If anything above us is unlocked, we can't use 'top' protection */ 185 if (!spi_nor_is_locked_sr(nor, ofs + len, mtd->size - (ofs + len), 186 status_old)) 187 can_be_top = false; 188 189 if (!can_be_bottom && !can_be_top) 190 return -EINVAL; 191 192 /* Prefer top, if both are valid */ 193 use_top = can_be_top; 194 195 /* lock_len: length of region that should end up locked */ 196 if (use_top) 197 lock_len = mtd->size - ofs; 198 else 199 lock_len = ofs + len; 200 201 if (lock_len == mtd->size) { 202 val = mask; 203 } else { 204 min_prot_len = spi_nor_get_min_prot_length_sr(nor); 205 pow = ilog2(lock_len) - ilog2(min_prot_len) + 1; 206 val = pow << SR_BP_SHIFT; 207 208 if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3) 209 val = (val & ~SR_BP3) | SR_BP3_BIT6; 210 211 if (val & ~mask) 212 return -EINVAL; 213 214 /* Don't "lock" with no region! */ 215 if (!(val & mask)) 216 return -EINVAL; 217 } 218 219 status_new = (status_old & ~mask & ~tb_mask) | val; 220 221 /* 222 * Disallow further writes if WP# pin is neither left floating nor 223 * wrongly tied to GND (that includes internal pull-downs). 224 * WP# pin hard strapped to GND can be a valid use case. 225 */ 226 if (!(nor->flags & SNOR_F_NO_WP)) 227 status_new |= SR_SRWD; 228 229 if (!use_top) 230 status_new |= tb_mask; 231 232 /* Don't bother if they're the same */ 233 if (status_new == status_old) 234 return 0; 235 236 /* Only modify protection if it will not unlock other areas */ 237 if ((status_new & mask) < (status_old & mask)) 238 return -EINVAL; 239 240 return spi_nor_write_sr_and_check(nor, status_new); 241} 242 243/* 244 * Unlock a region of the flash. See spi_nor_sr_lock() for more info 245 * 246 * Returns negative on errors, 0 on success. 247 */ 248static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len) 249{ 250 struct mtd_info *mtd = &nor->mtd; 251 u64 min_prot_len; 252 int ret, status_old, status_new; 253 u8 mask = spi_nor_get_sr_bp_mask(nor); 254 u8 tb_mask = spi_nor_get_sr_tb_mask(nor); 255 u8 pow, val; 256 loff_t lock_len; 257 bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB; 258 bool use_top; 259 260 ret = spi_nor_read_sr(nor, nor->bouncebuf); 261 if (ret) 262 return ret; 263 264 status_old = nor->bouncebuf[0]; 265 266 /* If nothing in our range is locked, we don't need to do anything */ 267 if (spi_nor_is_unlocked_sr(nor, ofs, len, status_old)) 268 return 0; 269 270 /* If anything below us is locked, we can't use 'top' protection */ 271 if (!spi_nor_is_unlocked_sr(nor, 0, ofs, status_old)) 272 can_be_top = false; 273 274 /* If anything above us is locked, we can't use 'bottom' protection */ 275 if (!spi_nor_is_unlocked_sr(nor, ofs + len, mtd->size - (ofs + len), 276 status_old)) 277 can_be_bottom = false; 278 279 if (!can_be_bottom && !can_be_top) 280 return -EINVAL; 281 282 /* Prefer top, if both are valid */ 283 use_top = can_be_top; 284 285 /* lock_len: length of region that should remain locked */ 286 if (use_top) 287 lock_len = mtd->size - (ofs + len); 288 else 289 lock_len = ofs; 290 291 if (lock_len == 0) { 292 val = 0; /* fully unlocked */ 293 } else { 294 min_prot_len = spi_nor_get_min_prot_length_sr(nor); 295 pow = ilog2(lock_len) - ilog2(min_prot_len) + 1; 296 val = pow << SR_BP_SHIFT; 297 298 if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3) 299 val = (val & ~SR_BP3) | SR_BP3_BIT6; 300 301 /* Some power-of-two sizes are not supported */ 302 if (val & ~mask) 303 return -EINVAL; 304 } 305 306 status_new = (status_old & ~mask & ~tb_mask) | val; 307 308 /* Don't protect status register if we're fully unlocked */ 309 if (lock_len == 0) 310 status_new &= ~SR_SRWD; 311 312 if (!use_top) 313 status_new |= tb_mask; 314 315 /* Don't bother if they're the same */ 316 if (status_new == status_old) 317 return 0; 318 319 /* Only modify protection if it will not lock other areas */ 320 if ((status_new & mask) > (status_old & mask)) 321 return -EINVAL; 322 323 return spi_nor_write_sr_and_check(nor, status_new); 324} 325 326/* 327 * Check if a region of the flash is (completely) locked. See spi_nor_sr_lock() 328 * for more info. 329 * 330 * Returns 1 if entire region is locked, 0 if any portion is unlocked, and 331 * negative on errors. 332 */ 333static int spi_nor_sr_is_locked(struct spi_nor *nor, loff_t ofs, u64 len) 334{ 335 int ret; 336 337 ret = spi_nor_read_sr(nor, nor->bouncebuf); 338 if (ret) 339 return ret; 340 341 return spi_nor_is_locked_sr(nor, ofs, len, nor->bouncebuf[0]); 342} 343 344static const struct spi_nor_locking_ops spi_nor_sr_locking_ops = { 345 .lock = spi_nor_sr_lock, 346 .unlock = spi_nor_sr_unlock, 347 .is_locked = spi_nor_sr_is_locked, 348}; 349 350void spi_nor_init_default_locking_ops(struct spi_nor *nor) 351{ 352 nor->params->locking_ops = &spi_nor_sr_locking_ops; 353} 354 355static int spi_nor_lock(struct mtd_info *mtd, loff_t ofs, u64 len) 356{ 357 struct spi_nor *nor = mtd_to_spi_nor(mtd); 358 int ret; 359 360 ret = spi_nor_prep_and_lock(nor); 361 if (ret) 362 return ret; 363 364 ret = nor->params->locking_ops->lock(nor, ofs, len); 365 366 spi_nor_unlock_and_unprep(nor); 367 return ret; 368} 369 370static int spi_nor_unlock(struct mtd_info *mtd, loff_t ofs, u64 len) 371{ 372 struct spi_nor *nor = mtd_to_spi_nor(mtd); 373 int ret; 374 375 ret = spi_nor_prep_and_lock(nor); 376 if (ret) 377 return ret; 378 379 ret = nor->params->locking_ops->unlock(nor, ofs, len); 380 381 spi_nor_unlock_and_unprep(nor); 382 return ret; 383} 384 385static int spi_nor_is_locked(struct mtd_info *mtd, loff_t ofs, u64 len) 386{ 387 struct spi_nor *nor = mtd_to_spi_nor(mtd); 388 int ret; 389 390 ret = spi_nor_prep_and_lock(nor); 391 if (ret) 392 return ret; 393 394 ret = nor->params->locking_ops->is_locked(nor, ofs, len); 395 396 spi_nor_unlock_and_unprep(nor); 397 return ret; 398} 399 400/** 401 * spi_nor_try_unlock_all() - Tries to unlock the entire flash memory array. 402 * @nor: pointer to a 'struct spi_nor'. 403 * 404 * Some SPI NOR flashes are write protected by default after a power-on reset 405 * cycle, in order to avoid inadvertent writes during power-up. Backward 406 * compatibility imposes to unlock the entire flash memory array at power-up 407 * by default. 408 * 409 * Unprotecting the entire flash array will fail for boards which are hardware 410 * write-protected. Thus any errors are ignored. 411 */ 412void spi_nor_try_unlock_all(struct spi_nor *nor) 413{ 414 int ret; 415 416 if (!(nor->flags & SNOR_F_HAS_LOCK)) 417 return; 418 419 dev_dbg(nor->dev, "Unprotecting entire flash array\n"); 420 421 ret = spi_nor_unlock(&nor->mtd, 0, nor->params->size); 422 if (ret) 423 dev_dbg(nor->dev, "Failed to unlock the entire flash memory array\n"); 424} 425 426void spi_nor_set_mtd_locking_ops(struct spi_nor *nor) 427{ 428 struct mtd_info *mtd = &nor->mtd; 429 430 if (!nor->params->locking_ops) 431 return; 432 433 mtd->_lock = spi_nor_lock; 434 mtd->_unlock = spi_nor_unlock; 435 mtd->_is_locked = spi_nor_is_locked; 436} 437