From 2d284768b49bcf1c643c08a201ff2161041178ef Mon Sep 17 00:00:00 2001 From: Jungseung Lee Date: Wed, 18 Mar 2020 21:06:13 +0900 Subject: [PATCH] mtd: spi-nor: Add generic formula for SR block protection handling The current mainline locking was restricted and could only be applied to flashes that have 3 block protection bits and fixed locking ratio. A new method of normalization was reached at the end of the discussion [1]. (1) - if bp slot is insufficient. (2) - if bp slot is sufficient. if (bp_slots_needed > bp_slots) // (1) min_prot_length = sector_size << (bp_slots_needed - bp_slots); else // (2) min_prot_length = sector_size; This patch changes logic to handle block protection based on min_prot_length. It is suitable for the overall flashes with exception of some corner cases (see EON and catalyst) and easy to extend and apply for the case of 2bit or 4bit block protection. [1] http://lists.infradead.org/pipermail/linux-mtd/2020-February/093934.html Signed-off-by: Jungseung Lee Reviewed-by: Michael Walle Tested-by: Michael Walle Signed-off-by: Tudor Ambarus --- drivers/mtd/spi-nor/core.c | 72 ++++++++++++++++++++++---------------- 1 file changed, 41 insertions(+), 31 deletions(-) diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c index bc57b1b5ec62..8146d82afe61 100644 --- a/drivers/mtd/spi-nor/core.c +++ b/drivers/mtd/spi-nor/core.c @@ -1536,29 +1536,51 @@ erase_err: return ret; } +static u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor) +{ + unsigned int bp_slots, bp_slots_needed; + u8 mask = SR_BP2 | SR_BP1 | SR_BP0; + + /* Reserved one for "protect none" and one for "protect all". */ + bp_slots = (mask >> SR_BP_SHIFT) + 1 - 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 = SR_BP2 | SR_BP1 | SR_BP0; u8 tb_mask = SR_TB_BIT5; - int pow; + u8 bp = (sr & mask) >> SR_BP_SHIFT; if (nor->flags & SNOR_F_HAS_SR_TB_BIT6) tb_mask = SR_TB_BIT6; - if (!(sr & mask)) { + if (!bp) { /* No protection */ *ofs = 0; *len = 0; - } else { - pow = ((sr & mask) ^ mask) >> SR_BP_SHIFT; - *len = mtd->size >> pow; - if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask) - *ofs = 0; - else - *ofs = mtd->size - *len; + 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; } /* @@ -1631,6 +1653,7 @@ static int spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len, 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 = SR_BP2 | SR_BP1 | SR_BP0; u8 tb_mask = SR_TB_BIT5; @@ -1673,20 +1696,12 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len) if (nor->flags & SNOR_F_HAS_SR_TB_BIT6) tb_mask = SR_TB_BIT6; - /* - * 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)) - */ if (lock_len == mtd->size) { val = mask; } else { - pow = ilog2(mtd->size) - ilog2(lock_len); - val = mask - (pow << SR_BP_SHIFT); + 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 (val & ~mask) return -EINVAL; @@ -1723,6 +1738,7 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len) 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 = SR_BP2 | SR_BP1 | SR_BP0; u8 tb_mask = SR_TB_BIT5; @@ -1764,20 +1780,14 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len) if (nor->flags & SNOR_F_HAS_SR_TB_BIT6) tb_mask = SR_TB_BIT6; - /* - * 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(mtd->size) - order_base_2(lock_len); + if (lock_len == 0) { val = 0; /* fully unlocked */ } else { - val = mask - (pow << SR_BP_SHIFT); + 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; + /* Some power-of-two sizes are not supported */ if (val & ~mask) return -EINVAL;