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 13 static 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 26 static 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 34 static u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor) 35 { 36 unsigned int bp_slots, bp_slots_needed; 37 u8 mask = spi_nor_get_sr_bp_mask(nor); 38 39 /* Reserved one for "protect none" and one for "protect all". */ 40 bp_slots = (1 << hweight8(mask)) - 2; 41 bp_slots_needed = ilog2(nor->info->n_sectors); 42 43 if (bp_slots_needed > bp_slots) 44 return nor->info->sector_size << 45 (bp_slots_needed - bp_slots); 46 else 47 return nor->info->sector_size; 48 } 49 50 static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs, 51 uint64_t *len) 52 { 53 struct mtd_info *mtd = &nor->mtd; 54 u64 min_prot_len; 55 u8 mask = spi_nor_get_sr_bp_mask(nor); 56 u8 tb_mask = spi_nor_get_sr_tb_mask(nor); 57 u8 bp, val = sr & mask; 58 59 if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6) 60 val = (val & ~SR_BP3_BIT6) | SR_BP3; 61 62 bp = val >> SR_BP_SHIFT; 63 64 if (!bp) { 65 /* No protection */ 66 *ofs = 0; 67 *len = 0; 68 return; 69 } 70 71 min_prot_len = spi_nor_get_min_prot_length_sr(nor); 72 *len = min_prot_len << (bp - 1); 73 74 if (*len > mtd->size) 75 *len = mtd->size; 76 77 if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask) 78 *ofs = 0; 79 else 80 *ofs = mtd->size - *len; 81 } 82 83 /* 84 * Return true if the entire region is locked (if @locked is true) or unlocked 85 * (if @locked is false); false otherwise. 86 */ 87 static bool spi_nor_check_lock_status_sr(struct spi_nor *nor, loff_t ofs, 88 uint64_t len, u8 sr, bool locked) 89 { 90 loff_t lock_offs, lock_offs_max, offs_max; 91 uint64_t lock_len; 92 93 if (!len) 94 return true; 95 96 spi_nor_get_locked_range_sr(nor, sr, &lock_offs, &lock_len); 97 98 lock_offs_max = lock_offs + lock_len; 99 offs_max = ofs + len; 100 101 if (locked) 102 /* Requested range is a sub-range of locked range */ 103 return (offs_max <= lock_offs_max) && (ofs >= lock_offs); 104 else 105 /* Requested range does not overlap with locked range */ 106 return (ofs >= lock_offs_max) || (offs_max <= lock_offs); 107 } 108 109 static bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len, 110 u8 sr) 111 { 112 return spi_nor_check_lock_status_sr(nor, ofs, len, sr, true); 113 } 114 115 static bool spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, 116 uint64_t len, u8 sr) 117 { 118 return spi_nor_check_lock_status_sr(nor, ofs, len, sr, false); 119 } 120 121 /* 122 * Lock a region of the flash. Compatible with ST Micro and similar flash. 123 * Supports the block protection bits BP{0,1,2}/BP{0,1,2,3} in the status 124 * register 125 * (SR). Does not support these features found in newer SR bitfields: 126 * - SEC: sector/block protect - only handle SEC=0 (block protect) 127 * - CMP: complement protect - only support CMP=0 (range is not complemented) 128 * 129 * Support for the following is provided conditionally for some flash: 130 * - TB: top/bottom protect 131 * 132 * Sample table portion for 8MB flash (Winbond w25q64fw): 133 * 134 * SEC | TB | BP2 | BP1 | BP0 | Prot Length | Protected Portion 135 * -------------------------------------------------------------------------- 136 * X | X | 0 | 0 | 0 | NONE | NONE 137 * 0 | 0 | 0 | 0 | 1 | 128 KB | Upper 1/64 138 * 0 | 0 | 0 | 1 | 0 | 256 KB | Upper 1/32 139 * 0 | 0 | 0 | 1 | 1 | 512 KB | Upper 1/16 140 * 0 | 0 | 1 | 0 | 0 | 1 MB | Upper 1/8 141 * 0 | 0 | 1 | 0 | 1 | 2 MB | Upper 1/4 142 * 0 | 0 | 1 | 1 | 0 | 4 MB | Upper 1/2 143 * X | X | 1 | 1 | 1 | 8 MB | ALL 144 * ------|-------|-------|-------|-------|---------------|------------------- 145 * 0 | 1 | 0 | 0 | 1 | 128 KB | Lower 1/64 146 * 0 | 1 | 0 | 1 | 0 | 256 KB | Lower 1/32 147 * 0 | 1 | 0 | 1 | 1 | 512 KB | Lower 1/16 148 * 0 | 1 | 1 | 0 | 0 | 1 MB | Lower 1/8 149 * 0 | 1 | 1 | 0 | 1 | 2 MB | Lower 1/4 150 * 0 | 1 | 1 | 1 | 0 | 4 MB | Lower 1/2 151 * 152 * Returns negative on errors, 0 on success. 153 */ 154 static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len) 155 { 156 struct mtd_info *mtd = &nor->mtd; 157 u64 min_prot_len; 158 int ret, status_old, status_new; 159 u8 mask = spi_nor_get_sr_bp_mask(nor); 160 u8 tb_mask = spi_nor_get_sr_tb_mask(nor); 161 u8 pow, val; 162 loff_t lock_len; 163 bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB; 164 bool use_top; 165 166 ret = spi_nor_read_sr(nor, nor->bouncebuf); 167 if (ret) 168 return ret; 169 170 status_old = nor->bouncebuf[0]; 171 172 /* If nothing in our range is unlocked, we don't need to do anything */ 173 if (spi_nor_is_locked_sr(nor, ofs, len, status_old)) 174 return 0; 175 176 /* If anything below us is unlocked, we can't use 'bottom' protection */ 177 if (!spi_nor_is_locked_sr(nor, 0, ofs, status_old)) 178 can_be_bottom = false; 179 180 /* If anything above us is unlocked, we can't use 'top' protection */ 181 if (!spi_nor_is_locked_sr(nor, ofs + len, mtd->size - (ofs + len), 182 status_old)) 183 can_be_top = false; 184 185 if (!can_be_bottom && !can_be_top) 186 return -EINVAL; 187 188 /* Prefer top, if both are valid */ 189 use_top = can_be_top; 190 191 /* lock_len: length of region that should end up locked */ 192 if (use_top) 193 lock_len = mtd->size - ofs; 194 else 195 lock_len = ofs + len; 196 197 if (lock_len == mtd->size) { 198 val = mask; 199 } else { 200 min_prot_len = spi_nor_get_min_prot_length_sr(nor); 201 pow = ilog2(lock_len) - ilog2(min_prot_len) + 1; 202 val = pow << SR_BP_SHIFT; 203 204 if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3) 205 val = (val & ~SR_BP3) | SR_BP3_BIT6; 206 207 if (val & ~mask) 208 return -EINVAL; 209 210 /* Don't "lock" with no region! */ 211 if (!(val & mask)) 212 return -EINVAL; 213 } 214 215 status_new = (status_old & ~mask & ~tb_mask) | val; 216 217 /* Disallow further writes if WP pin is asserted */ 218 status_new |= SR_SRWD; 219 220 if (!use_top) 221 status_new |= tb_mask; 222 223 /* Don't bother if they're the same */ 224 if (status_new == status_old) 225 return 0; 226 227 /* Only modify protection if it will not unlock other areas */ 228 if ((status_new & mask) < (status_old & mask)) 229 return -EINVAL; 230 231 return spi_nor_write_sr_and_check(nor, status_new); 232 } 233 234 /* 235 * Unlock a region of the flash. See spi_nor_sr_lock() for more info 236 * 237 * Returns negative on errors, 0 on success. 238 */ 239 static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len) 240 { 241 struct mtd_info *mtd = &nor->mtd; 242 u64 min_prot_len; 243 int ret, status_old, status_new; 244 u8 mask = spi_nor_get_sr_bp_mask(nor); 245 u8 tb_mask = spi_nor_get_sr_tb_mask(nor); 246 u8 pow, val; 247 loff_t lock_len; 248 bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB; 249 bool use_top; 250 251 ret = spi_nor_read_sr(nor, nor->bouncebuf); 252 if (ret) 253 return ret; 254 255 status_old = nor->bouncebuf[0]; 256 257 /* If nothing in our range is locked, we don't need to do anything */ 258 if (spi_nor_is_unlocked_sr(nor, ofs, len, status_old)) 259 return 0; 260 261 /* If anything below us is locked, we can't use 'top' protection */ 262 if (!spi_nor_is_unlocked_sr(nor, 0, ofs, status_old)) 263 can_be_top = false; 264 265 /* If anything above us is locked, we can't use 'bottom' protection */ 266 if (!spi_nor_is_unlocked_sr(nor, ofs + len, mtd->size - (ofs + len), 267 status_old)) 268 can_be_bottom = false; 269 270 if (!can_be_bottom && !can_be_top) 271 return -EINVAL; 272 273 /* Prefer top, if both are valid */ 274 use_top = can_be_top; 275 276 /* lock_len: length of region that should remain locked */ 277 if (use_top) 278 lock_len = mtd->size - (ofs + len); 279 else 280 lock_len = ofs; 281 282 if (lock_len == 0) { 283 val = 0; /* fully unlocked */ 284 } else { 285 min_prot_len = spi_nor_get_min_prot_length_sr(nor); 286 pow = ilog2(lock_len) - ilog2(min_prot_len) + 1; 287 val = pow << SR_BP_SHIFT; 288 289 if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3) 290 val = (val & ~SR_BP3) | SR_BP3_BIT6; 291 292 /* Some power-of-two sizes are not supported */ 293 if (val & ~mask) 294 return -EINVAL; 295 } 296 297 status_new = (status_old & ~mask & ~tb_mask) | val; 298 299 /* Don't protect status register if we're fully unlocked */ 300 if (lock_len == 0) 301 status_new &= ~SR_SRWD; 302 303 if (!use_top) 304 status_new |= tb_mask; 305 306 /* Don't bother if they're the same */ 307 if (status_new == status_old) 308 return 0; 309 310 /* Only modify protection if it will not lock other areas */ 311 if ((status_new & mask) > (status_old & mask)) 312 return -EINVAL; 313 314 return spi_nor_write_sr_and_check(nor, status_new); 315 } 316 317 /* 318 * Check if a region of the flash is (completely) locked. See spi_nor_sr_lock() 319 * for more info. 320 * 321 * Returns 1 if entire region is locked, 0 if any portion is unlocked, and 322 * negative on errors. 323 */ 324 static int spi_nor_sr_is_locked(struct spi_nor *nor, loff_t ofs, uint64_t len) 325 { 326 int ret; 327 328 ret = spi_nor_read_sr(nor, nor->bouncebuf); 329 if (ret) 330 return ret; 331 332 return spi_nor_is_locked_sr(nor, ofs, len, nor->bouncebuf[0]); 333 } 334 335 static const struct spi_nor_locking_ops spi_nor_sr_locking_ops = { 336 .lock = spi_nor_sr_lock, 337 .unlock = spi_nor_sr_unlock, 338 .is_locked = spi_nor_sr_is_locked, 339 }; 340 341 void spi_nor_init_default_locking_ops(struct spi_nor *nor) 342 { 343 nor->params->locking_ops = &spi_nor_sr_locking_ops; 344 } 345 346 static int spi_nor_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len) 347 { 348 struct spi_nor *nor = mtd_to_spi_nor(mtd); 349 int ret; 350 351 ret = spi_nor_lock_and_prep(nor); 352 if (ret) 353 return ret; 354 355 ret = nor->params->locking_ops->lock(nor, ofs, len); 356 357 spi_nor_unlock_and_unprep(nor); 358 return ret; 359 } 360 361 static int spi_nor_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len) 362 { 363 struct spi_nor *nor = mtd_to_spi_nor(mtd); 364 int ret; 365 366 ret = spi_nor_lock_and_prep(nor); 367 if (ret) 368 return ret; 369 370 ret = nor->params->locking_ops->unlock(nor, ofs, len); 371 372 spi_nor_unlock_and_unprep(nor); 373 return ret; 374 } 375 376 static int spi_nor_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len) 377 { 378 struct spi_nor *nor = mtd_to_spi_nor(mtd); 379 int ret; 380 381 ret = spi_nor_lock_and_prep(nor); 382 if (ret) 383 return ret; 384 385 ret = nor->params->locking_ops->is_locked(nor, ofs, len); 386 387 spi_nor_unlock_and_unprep(nor); 388 return ret; 389 } 390 391 /** 392 * spi_nor_try_unlock_all() - Tries to unlock the entire flash memory array. 393 * @nor: pointer to a 'struct spi_nor'. 394 * 395 * Some SPI NOR flashes are write protected by default after a power-on reset 396 * cycle, in order to avoid inadvertent writes during power-up. Backward 397 * compatibility imposes to unlock the entire flash memory array at power-up 398 * by default. 399 * 400 * Unprotecting the entire flash array will fail for boards which are hardware 401 * write-protected. Thus any errors are ignored. 402 */ 403 void spi_nor_try_unlock_all(struct spi_nor *nor) 404 { 405 int ret; 406 407 if (!(nor->flags & SNOR_F_HAS_LOCK)) 408 return; 409 410 dev_dbg(nor->dev, "Unprotecting entire flash array\n"); 411 412 ret = spi_nor_unlock(&nor->mtd, 0, nor->params->size); 413 if (ret) 414 dev_dbg(nor->dev, "Failed to unlock the entire flash memory array\n"); 415 } 416 417 void spi_nor_register_locking_ops(struct spi_nor *nor) 418 { 419 struct mtd_info *mtd = &nor->mtd; 420 421 if (!nor->params->locking_ops) 422 return; 423 424 mtd->_lock = spi_nor_lock; 425 mtd->_unlock = spi_nor_unlock; 426 mtd->_is_locked = spi_nor_is_locked; 427 } 428