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-rw-r--r--drivers/mtd/spi-nor/swp.c427
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 000000000..1f178313b
--- /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_set_mtd_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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-26 23:49:02 +0000