diff options
Diffstat (limited to 'drivers/mtd/spi-nor/swp.c')
| -rw-r--r-- | drivers/mtd/spi-nor/swp.c | 427 |
1 files changed, 427 insertions, 0 deletions
diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c new file mode 100644 index 000000000000..8594bcbb7dbe --- /dev/null +++ b/drivers/mtd/spi-nor/swp.c @@ -0,0 +1,427 @@ +// 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 <linux/mtd/mtd.h> +#include <linux/mtd/spi-nor.h> + +#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; +} |