Add the SPI NOR protection mechanism from the kernel.
This code is based on the work from Brian Norris computersforpeace@gmail.com https://patchwork.ozlabs.org/patch/513041/
Signed-off-by: Fabio Estevam fabio.estevam@freescale.com --- Changes since v5: - None
drivers/mtd/spi/sf_ops.c | 188 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 188 insertions(+)
diff --git a/drivers/mtd/spi/sf_ops.c b/drivers/mtd/spi/sf_ops.c index 900ec1f..0f7a31d 100644 --- a/drivers/mtd/spi/sf_ops.c +++ b/drivers/mtd/spi/sf_ops.c @@ -573,3 +573,191 @@ int sst_write_bp(struct spi_flash *flash, u32 offset, size_t len, return ret; } #endif + +#ifdef CONFIG_SPI_FLASH_STMICRO +#define SR_BP0 BIT(2) /* Block protect 0 */ +#define SR_BP1 BIT(3) /* Block protect 1 */ +#define SR_BP2 BIT(4) /* Block protect 2 */ + +static void stm_get_locked_range(struct spi_flash *nor, u8 sr, loff_t *ofs, + u32 *len) +{ + u8 mask = SR_BP2 | SR_BP1 | SR_BP0; + int shift = ffs(mask) - 1; + int pow; + + if (!(sr & mask)) { + /* No protection */ + *ofs = 0; + *len = 0; + } else { + pow = ((sr & mask) ^ mask) >> shift; + *len = nor->size >> pow; + *ofs = nor->size - *len; + } +} + +/* + * Return 1 if the entire region is locked, 0 otherwise + */ +static int stm_is_locked_sr(struct spi_flash *nor, loff_t ofs, u32 len, + u8 sr) +{ + loff_t lock_offs; + u32 lock_len; + + stm_get_locked_range(nor, sr, &lock_offs, &lock_len); + + return (ofs + len <= lock_offs + lock_len) && (ofs >= lock_offs); +} + +/* + * Check if a region of the flash is (completely) locked. See stm_lock() for + * more info. + * + * Returns 1 if entire region is locked, 0 if any portion is unlocked, and + * negative on errors. + */ +int stm_is_locked(struct spi_flash *nor, loff_t ofs, u32 len) +{ + int status; + u8 sr; + + status = spi_flash_cmd_read_status(nor, &sr); + if (status < 0) + return status; + + return stm_is_locked_sr(nor, ofs, len, sr); +} + +/* + * Lock a region of the flash. Compatible with ST Micro and similar flash. + * Supports only the block protection bits BP{0,1,2} in the status register + * (SR). Does not support these features found in newer SR bitfields: + * - TB: top/bottom protect - only handle TB=0 (top protect) + * - SEC: sector/block protect - only handle SEC=0 (block protect) + * - CMP: complement protect - only support CMP=0 (range is not complemented) + * + * 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 + * + * Returns negative on errors, 0 on success. + */ +int stm_lock(struct spi_flash *nor, u32 ofs, u32 len) +{ + u8 status_old, status_new; + u8 mask = SR_BP2 | SR_BP1 | SR_BP0; + u8 shift = ffs(mask) - 1, pow, val; + + spi_flash_cmd_read_status(nor, &status_old); + + /* SPI NOR always locks to the end */ + if (ofs + len != nor->size) { + /* Does combined region extend to end? */ + if (!stm_is_locked_sr(nor, ofs + len, nor->size - ofs - len, + status_old)) + return -EINVAL; + len = nor->size - ofs; + } + + /* + * Need smallest pow such that: + * + * 1 / (2^pow) <= (len / size) + * + * so (assuming power-of-2 size) we do: + * + * pow = ceil(log2(size / len)) = log2(size) - floor(log2(len)) + */ + pow = __ilog2(nor->size) - __ilog2(len); + val = mask - (pow << shift); + if (val & ~mask) + return -EINVAL; + + /* Don't "lock" with no region! */ + if (!(val & mask)) + return -EINVAL; + + status_new = (status_old & ~mask) | val; + + /* Only modify protection if it will not unlock other areas */ + if ((status_new & mask) <= (status_old & mask)) + return -EINVAL; + + spi_flash_cmd_write_status(nor, status_new); + + return 0; +} + +/* + * Unlock a region of the flash. See stm_lock() for more info + * + * Returns negative on errors, 0 on success. + */ +int stm_unlock(struct spi_flash *nor, u32 ofs, u32 len) +{ + uint8_t status_old, status_new; + u8 mask = SR_BP2 | SR_BP1 | SR_BP0; + u8 shift = ffs(mask) - 1, pow, val; + + spi_flash_cmd_read_status(nor, &status_old); + + /* Cannot unlock; would unlock larger region than requested */ + if (stm_is_locked_sr(nor, status_old, ofs - nor->erase_size, + nor->erase_size)) + return -EINVAL; + /* + * Need largest pow such that: + * + * 1 / (2^pow) >= (len / size) + * + * so (assuming power-of-2 size) we do: + * + * pow = floor(log2(size / len)) = log2(size) - ceil(log2(len)) + */ + pow = __ilog2(nor->size) - order_base_2(nor->size - (ofs + len)); + if (ofs + len == nor->size) { + val = 0; /* fully unlocked */ + } else { + val = mask - (pow << shift); + /* Some power-of-two sizes are not supported */ + if (val & ~mask) + return -EINVAL; + } + + status_new = (status_old & ~mask) | val; + + /* Only modify protection if it will not lock other areas */ + if ((status_new & mask) >= (status_old & mask)) + return -EINVAL; + + spi_flash_cmd_write_status(nor, status_new); + + return 0; +} +#else +int stm_is_locked(struct spi_flash *nor, loff_t ofs, u32 len) +{ + return 0; +} + +int stm_lock(struct spi_flash *nor, u32 ofs, u32 len) +{ + return 0; +} + +int stm_unlock(struct spi_flash *nor, u32 ofs, u32 len) +{ + return 0; +} +#endif /* CONFIG_SPI_FLASH_STMICRO */