// SPDX-License-Identifier: GPL-2.0 /* * SPI NOR Software Write Protection logic. * * Copyright (C) 2005, Intec Automation Inc. * Copyright (C) 2014, Freescale Semiconductor, Inc. */ #include #include #include "core.h" static u8 spi_nor_get_sr_bp_mask(struct spi_nor *nor) { u8 mask = SR_BP2 | SR_BP1 | SR_BP0; if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6) return mask | SR_BP3_BIT6; if (nor->flags & SNOR_F_HAS_4BIT_BP) return mask | SR_BP3; return mask; } static u8 spi_nor_get_sr_tb_mask(struct spi_nor *nor) { if (nor->flags & SNOR_F_HAS_SR_TB_BIT6) return SR_TB_BIT6; else return SR_TB_BIT5; } static u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor) { unsigned int bp_slots, bp_slots_needed; u8 mask = spi_nor_get_sr_bp_mask(nor); /* Reserved one for "protect none" and one for "protect all". */ bp_slots = (1 << hweight8(mask)) - 2; bp_slots_needed = ilog2(nor->info->n_sectors); if (bp_slots_needed > bp_slots) return nor->info->sector_size << (bp_slots_needed - bp_slots); else return nor->info->sector_size; } static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs, uint64_t *len) { struct mtd_info *mtd = &nor->mtd; u64 min_prot_len; u8 mask = spi_nor_get_sr_bp_mask(nor); u8 tb_mask = spi_nor_get_sr_tb_mask(nor); u8 bp, val = sr & mask; if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6) val = (val & ~SR_BP3_BIT6) | SR_BP3; bp = val >> SR_BP_SHIFT; if (!bp) { /* No protection */ *ofs = 0; *len = 0; return; } min_prot_len = spi_nor_get_min_prot_length_sr(nor); *len = min_prot_len << (bp - 1); if (*len > mtd->size) *len = mtd->size; if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask) *ofs = 0; else *ofs = mtd->size - *len; } /* * Return true if the entire region is locked (if @locked is true) or unlocked * (if @locked is false); false otherwise. */ static bool spi_nor_check_lock_status_sr(struct spi_nor *nor, loff_t ofs, uint64_t len, u8 sr, bool locked) { loff_t lock_offs, lock_offs_max, offs_max; uint64_t lock_len; if (!len) return true; spi_nor_get_locked_range_sr(nor, sr, &lock_offs, &lock_len); lock_offs_max = lock_offs + lock_len; offs_max = ofs + len; if (locked) /* Requested range is a sub-range of locked range */ return (offs_max <= lock_offs_max) && (ofs >= lock_offs); else /* Requested range does not overlap with locked range */ return (ofs >= lock_offs_max) || (offs_max <= lock_offs); } static bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len, u8 sr) { return spi_nor_check_lock_status_sr(nor, ofs, len, sr, true); } static bool spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len, u8 sr) { return spi_nor_check_lock_status_sr(nor, ofs, len, sr, false); } /* * Lock a region of the flash. Compatible with ST Micro and similar flash. * Supports the block protection bits BP{0,1,2}/BP{0,1,2,3} in the status * register * (SR). Does not support these features found in newer SR bitfields: * - SEC: sector/block protect - only handle SEC=0 (block protect) * - CMP: complement protect - only support CMP=0 (range is not complemented) * * Support for the following is provided conditionally for some flash: * - TB: top/bottom protect * * Sample table portion for 8MB flash (Winbond w25q64fw): * * SEC | TB | BP2 | BP1 | BP0 | Prot Length | Protected Portion * -------------------------------------------------------------------------- * X | X | 0 | 0 | 0 | NONE | NONE * 0 | 0 | 0 | 0 | 1 | 128 KB | Upper 1/64 * 0 | 0 | 0 | 1 | 0 | 256 KB | Upper 1/32 * 0 | 0 | 0 | 1 | 1 | 512 KB | Upper 1/16 * 0 | 0 | 1 | 0 | 0 | 1 MB | Upper 1/8 * 0 | 0 | 1 | 0 | 1 | 2 MB | Upper 1/4 * 0 | 0 | 1 | 1 | 0 | 4 MB | Upper 1/2 * X | X | 1 | 1 | 1 | 8 MB | ALL * ------|-------|-------|-------|-------|---------------|------------------- * 0 | 1 | 0 | 0 | 1 | 128 KB | Lower 1/64 * 0 | 1 | 0 | 1 | 0 | 256 KB | Lower 1/32 * 0 | 1 | 0 | 1 | 1 | 512 KB | Lower 1/16 * 0 | 1 | 1 | 0 | 0 | 1 MB | Lower 1/8 * 0 | 1 | 1 | 0 | 1 | 2 MB | Lower 1/4 * 0 | 1 | 1 | 1 | 0 | 4 MB | Lower 1/2 * * Returns negative on errors, 0 on success. */ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len) { struct mtd_info *mtd = &nor->mtd; u64 min_prot_len; int ret, status_old, status_new; u8 mask = spi_nor_get_sr_bp_mask(nor); u8 tb_mask = spi_nor_get_sr_tb_mask(nor); u8 pow, val; loff_t lock_len; bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB; bool use_top; ret = spi_nor_read_sr(nor, nor->bouncebuf); if (ret) return ret; status_old = nor->bouncebuf[0]; /* If nothing in our range is unlocked, we don't need to do anything */ if (spi_nor_is_locked_sr(nor, ofs, len, status_old)) return 0; /* If anything below us is unlocked, we can't use 'bottom' protection */ if (!spi_nor_is_locked_sr(nor, 0, ofs, status_old)) can_be_bottom = false; /* If anything above us is unlocked, we can't use 'top' protection */ if (!spi_nor_is_locked_sr(nor, ofs + len, mtd->size - (ofs + len), status_old)) can_be_top = false; if (!can_be_bottom && !can_be_top) return -EINVAL; /* Prefer top, if both are valid */ use_top = can_be_top; /* lock_len: length of region that should end up locked */ if (use_top) lock_len = mtd->size - ofs; else lock_len = ofs + len; if (lock_len == mtd->size) { val = mask; } else { min_prot_len = spi_nor_get_min_prot_length_sr(nor); pow = ilog2(lock_len) - ilog2(min_prot_len) + 1; val = pow << SR_BP_SHIFT; if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3) val = (val & ~SR_BP3) | SR_BP3_BIT6; if (val & ~mask) return -EINVAL; /* Don't "lock" with no region! */ if (!(val & mask)) return -EINVAL; } status_new = (status_old & ~mask & ~tb_mask) | val; /* Disallow further writes if WP pin is asserted */ status_new |= SR_SRWD; if (!use_top) status_new |= tb_mask; /* Don't bother if they're the same */ if (status_new == status_old) return 0; /* Only modify protection if it will not unlock other areas */ if ((status_new & mask) < (status_old & mask)) return -EINVAL; return spi_nor_write_sr_and_check(nor, status_new); } /* * Unlock a region of the flash. See spi_nor_sr_lock() for more info * * Returns negative on errors, 0 on success. */ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len) { struct mtd_info *mtd = &nor->mtd; u64 min_prot_len; int ret, status_old, status_new; u8 mask = spi_nor_get_sr_bp_mask(nor); u8 tb_mask = spi_nor_get_sr_tb_mask(nor); u8 pow, val; loff_t lock_len; bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB; bool use_top; ret = spi_nor_read_sr(nor, nor->bouncebuf); if (ret) return ret; status_old = nor->bouncebuf[0]; /* If nothing in our range is locked, we don't need to do anything */ if (spi_nor_is_unlocked_sr(nor, ofs, len, status_old)) return 0; /* If anything below us is locked, we can't use 'top' protection */ if (!spi_nor_is_unlocked_sr(nor, 0, ofs, status_old)) can_be_top = false; /* If anything above us is locked, we can't use 'bottom' protection */ if (!spi_nor_is_unlocked_sr(nor, ofs + len, mtd->size - (ofs + len), status_old)) can_be_bottom = false; if (!can_be_bottom && !can_be_top) return -EINVAL; /* Prefer top, if both are valid */ use_top = can_be_top; /* lock_len: length of region that should remain locked */ if (use_top) lock_len = mtd->size - (ofs + len); else lock_len = ofs; if (lock_len == 0) { val = 0; /* fully unlocked */ } else { min_prot_len = spi_nor_get_min_prot_length_sr(nor); pow = ilog2(lock_len) - ilog2(min_prot_len) + 1; val = pow << SR_BP_SHIFT; if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3) val = (val & ~SR_BP3) | SR_BP3_BIT6; /* Some power-of-two sizes are not supported */ if (val & ~mask) return -EINVAL; } status_new = (status_old & ~mask & ~tb_mask) | val; /* Don't protect status register if we're fully unlocked */ if (lock_len == 0) status_new &= ~SR_SRWD; if (!use_top) status_new |= tb_mask; /* Don't bother if they're the same */ if (status_new == status_old) return 0; /* Only modify protection if it will not lock other areas */ if ((status_new & mask) > (status_old & mask)) return -EINVAL; return spi_nor_write_sr_and_check(nor, status_new); } /* * Check if a region of the flash is (completely) locked. See spi_nor_sr_lock() * for more info. * * Returns 1 if entire region is locked, 0 if any portion is unlocked, and * negative on errors. */ static int spi_nor_sr_is_locked(struct spi_nor *nor, loff_t ofs, uint64_t len) { int ret; ret = spi_nor_read_sr(nor, nor->bouncebuf); if (ret) return ret; return spi_nor_is_locked_sr(nor, ofs, len, nor->bouncebuf[0]); } static const struct spi_nor_locking_ops spi_nor_sr_locking_ops = { .lock = spi_nor_sr_lock, .unlock = spi_nor_sr_unlock, .is_locked = spi_nor_sr_is_locked, }; void spi_nor_init_default_locking_ops(struct spi_nor *nor) { nor->params->locking_ops = &spi_nor_sr_locking_ops; } static int spi_nor_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len) { struct spi_nor *nor = mtd_to_spi_nor(mtd); int ret; ret = spi_nor_lock_and_prep(nor); if (ret) return ret; ret = nor->params->locking_ops->lock(nor, ofs, len); spi_nor_unlock_and_unprep(nor); return ret; } static int spi_nor_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len) { struct spi_nor *nor = mtd_to_spi_nor(mtd); int ret; ret = spi_nor_lock_and_prep(nor); if (ret) return ret; ret = nor->params->locking_ops->unlock(nor, ofs, len); spi_nor_unlock_and_unprep(nor); return ret; } static int spi_nor_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len) { struct spi_nor *nor = mtd_to_spi_nor(mtd); int ret; ret = spi_nor_lock_and_prep(nor); if (ret) return ret; ret = nor->params->locking_ops->is_locked(nor, ofs, len); spi_nor_unlock_and_unprep(nor); return ret; } /** * spi_nor_try_unlock_all() - Tries to unlock the entire flash memory array. * @nor: pointer to a 'struct spi_nor'. * * Some SPI NOR flashes are write protected by default after a power-on reset * cycle, in order to avoid inadvertent writes during power-up. Backward * compatibility imposes to unlock the entire flash memory array at power-up * by default. * * Unprotecting the entire flash array will fail for boards which are hardware * write-protected. Thus any errors are ignored. */ void spi_nor_try_unlock_all(struct spi_nor *nor) { int ret; if (!(nor->flags & SNOR_F_HAS_LOCK)) return; dev_dbg(nor->dev, "Unprotecting entire flash array\n"); ret = spi_nor_unlock(&nor->mtd, 0, nor->params->size); if (ret) dev_dbg(nor->dev, "Failed to unlock the entire flash memory array\n"); } void spi_nor_register_locking_ops(struct spi_nor *nor) { struct mtd_info *mtd = &nor->mtd; if (!nor->params->locking_ops) return; mtd->_lock = spi_nor_lock; mtd->_unlock = spi_nor_unlock; mtd->_is_locked = spi_nor_is_locked; }