[PATCH v2 30/30] mtd: spi-nor: Add support for locking on Spansion nor flashes
Tejas Bhumkar
tejas.arvind.bhumkar at amd.com
Wed Dec 6 10:31:41 CET 2023
From: Venkatesh Yadav Abbarapu <venkatesh.abbarapu at amd.com>
Spansion nor flashes provide block protection support using
BP0, BP1, BP2 bits in status register.
The top/bottom select is instead done via a bit in the configuration
register, which is OTP, so once set to use bottom protect, one cannot
use top. On top of that, reading the configuration register uses a
different opcode (0x15) than the existing SPINOR_OP_RDCR (0x35).
Used bottom protect to test s25fl512s flash part lock/unlock
on zc1751+dc1 board.
Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu at amd.com>
Signed-off-by: Tejas Bhumkar <tejas.arvind.bhumkar at amd.com>
---
drivers/mtd/spi/spi-nor-core.c | 372 +++++++++++++++++++++++++++++++++
include/linux/mtd/spi-nor.h | 1 +
2 files changed, 373 insertions(+)
diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 3e2491cc3e..42483caaaa 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -5465,6 +5465,370 @@ static int giga_flash_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
return ret;
}
#endif /* CONFIG_SPI_FLASH_GIGADEVICE */
+
+#if defined(CONFIG_SPI_FLASH_SPANSION)
+/**
+ * spansion_read_cr() - read configuration register
+ * @nor: pointer to a 'struct spi_nor'.
+ *
+ * Spansion devices have top/bottom area protection bits selection into
+ * configuration reg. The bits in CR are OTP. So once it's written,
+ * it cannot be changed.
+ *
+ * Return: Value in configuration register or negative if error.
+ */
+static int spansion_read_cr(struct spi_nor *nor)
+{
+ int ret;
+ u8 val;
+
+ ret = nor->read_reg(nor, SPINOR_OP_RDCR, &val, 1);
+ if (ret < 0) {
+ dev_dbg(nor->dev, "error %d reading CR\n", ret);
+ return ret;
+ }
+
+ return val;
+}
+
+static void spansion_get_locked_range(struct spi_nor *nor, u8 sr, loff_t *ofs,
+ uint64_t *len)
+{
+ struct mtd_info *mtd = &nor->mtd;
+ int pow, cr;
+ int shift = 0;
+ u8 mask = SR_BP0 | SR_BP1 | SR_BP2;
+
+ shift = ffs(mask) - 1;
+
+ cr = spansion_read_cr(nor);
+ if (!(sr & mask)) {
+ /* No protection */
+ *ofs = 0;
+ *len = 0;
+ } else {
+ pow = ((sr & mask) ^ mask) >> shift;
+ *len = mtd->size >> pow;
+ /* SPANSION device's have top/bottom select bit in configuration reg */
+ if (nor->flags & SNOR_F_HAS_SR_TB && cr & CR_TB_SPAN)
+ *ofs = 0;
+ else
+ *ofs = mtd->size - *len;
+ }
+}
+
+/**
+ * spansion_check_lock_status_sr() - check the status register and return
+ * the region is locked or unlocked
+ * @nor: pointer to a 'struct spi_nor'.
+ * @ofs: offset of the flash
+ * @len: length to be locked
+ * @sr: status register
+ * @locked: locked:1 unlocked:0 value
+ *
+ * Return: 1 if the entire region is locked (if @locked is true) or unlocked (if
+ * @locked is false); 0 otherwise.
+ */
+static int spansion_check_lock_status_sr(struct spi_nor *nor, loff_t ofs, u64 len,
+ u8 sr, bool locked)
+{
+ loff_t lock_offs;
+ u64 lock_len;
+
+ if (!len)
+ return 1;
+
+ spansion_get_locked_range(nor, sr, &lock_offs, &lock_len);
+ if (locked)
+ /* Requested range is a sub-range of locked range */
+ return (ofs + len <= lock_offs + lock_len) && (ofs >= lock_offs);
+
+ /* Requested range does not overlap with locked range */
+ return (ofs >= lock_offs + lock_len) || (ofs + len <= lock_offs);
+}
+
+/**
+ * spansion_is_locked_sr() - check if the memory region is locked
+ * @nor: pointer to a 'struct spi_nor'.
+ * @ofs: offset of the flash
+ * @len: length to be locked
+ * @sr: status register
+ *
+ * Check if memory region is locked.
+ *
+ * Return: false if region is locked 0 otherwise.
+ */
+static int spansion_is_locked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
+ u8 sr)
+{
+ return spansion_check_lock_status_sr(nor, ofs, len, sr, true);
+}
+
+/**
+ * spansion_is_unlocked_sr() - check if the memory region is unlocked
+ * @nor: pointer to a 'struct spi_nor'.
+ * @ofs: offset of the flash
+ * @len: length to be locked
+ * @sr: status register
+ *
+ * Check if memory region is unlocked.
+ *
+ * Return: false if region is locked 0 otherwise.
+ */
+static int spansion_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
+ u8 sr)
+{
+ return spansion_check_lock_status_sr(nor, ofs, len, sr, false);
+}
+
+/**
+ * spansion_is_unlocked() - check if the memory region is unlocked
+ * @nor: pointer to a 'struct spi_nor'.
+ * @ofs: offset of the flash
+ * @len: length to be locked
+ *
+ * check if memory region is unlocked
+ *
+ * Return: false if region is locked 0 otherwise.
+ */
+static int spansion_is_unlocked(struct spi_nor *nor, loff_t ofs, uint64_t len)
+{
+ int sr;
+
+ sr = read_sr(nor);
+ if (sr < 0)
+ return sr;
+
+ return spansion_check_lock_status_sr(nor, ofs, len, sr, false);
+}
+
+/**
+ * spansion_nor_select_zone() - Select top area or bottom area to lock/unlock
+ * @nor: pointer to a 'struct spi_nor'.
+ * @ofs: offset from which to lock memory.
+ * @len: number of bytes to unlock.
+ * @sr: status register
+ * @tb: pointer to top/bottom bool used in caller function
+ * @op: zone selection is for lock/unlock operation. 1: lock 0:unlock
+ *
+ * Select the top area / bottom area pattern to protect memory blocks.
+ *
+ * Return: negative on errors, 0 on success.
+ */
+static int spansion_nor_select_zone(struct spi_nor *nor, loff_t ofs, uint64_t len,
+ u8 sr, bool *tb, bool op)
+{
+ int retval = 1;
+ bool can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB, can_be_top = true;
+
+ if (op) {
+ /* Select for lock zone operation */
+
+ /*
+ * If nothing in our range is unlocked, we don't need
+ * to do anything.
+ */
+ if (spansion_is_locked_sr(nor, ofs, len, sr))
+ return 0;
+
+ /*
+ * If anything below us is unlocked, we can't use 'bottom'
+ * protection.
+ */
+ if (!spansion_is_locked_sr(nor, 0, ofs, sr))
+ can_be_bottom = false;
+
+ /*
+ * If anything above us is unlocked, we can't use 'top'
+ * protection.
+ */
+ if (!spansion_is_locked_sr(nor, ofs + len,
+ nor->mtd.size - (ofs + len), sr))
+ can_be_top = false;
+ } else {
+ /* Select unlock zone */
+
+ /*
+ * If nothing in our range is locked, we don't need to
+ * do anything.
+ */
+ if (spansion_is_unlocked_sr(nor, ofs, len, sr))
+ return 0;
+
+ /*
+ * If anything below us is locked, we can't use 'top'
+ * protection
+ */
+ if (!spansion_is_unlocked_sr(nor, 0, ofs, sr))
+ can_be_top = false;
+
+ /*
+ * If anything above us is locked, we can't use 'bottom'
+ * protection
+ */
+ if (!spansion_is_unlocked_sr(nor, ofs + len,
+ nor->mtd.size - (ofs + len), sr))
+ can_be_bottom = false;
+ }
+
+ if (!can_be_bottom && !can_be_top)
+ return -EINVAL;
+
+ /* Prefer top, if both are valid */
+ *tb = can_be_top;
+ return retval;
+}
+
+static int spansion_write_sr_cr(struct spi_nor *nor, u8 *sr_cr)
+{
+ int ret;
+
+ write_enable(nor);
+
+ ret = nor->write_reg(nor, SPINOR_OP_WRSR, sr_cr, 2);
+ if (ret < 0) {
+ dev_dbg(nor->dev,
+ "error while writing configuration register\n");
+ return -EINVAL;
+ }
+
+ ret = spi_nor_wait_till_ready(nor);
+ if (ret) {
+ dev_dbg(nor->dev,
+ "timeout while writing configuration register\n");
+ return ret;
+ }
+
+ ret = write_disable(nor);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+/**
+ * spansion_flash_lock() - set BP[012] write-protection.
+ * @nor: pointer to a 'struct spi_nor'.
+ * @ofs: offset from which to lock memory.
+ * @len: number of bytes to unlock.
+ *
+ * Lock a region of the flash.Implementation is based on stm_lock
+ * Supports the block protection bits BP{0,1,2} in status register
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spansion_flash_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
+{
+ u64 lock_len;
+ u32 sector_size;
+ u16 n_sectors;
+ unsigned int bp_slots, bp_slots_needed;
+ int cr, can_be_top, val, status_old;
+ u8 pow, ret, shift, sr_cr[2];
+ bool use_top = false;
+ u8 mask = SR_BP0 | SR_BP1 | SR_BP2;
+
+ shift = ffs(mask) - 1;
+
+ status_old = read_sr(nor);
+ /* if status reg is Write protected don't update bit protection */
+ if (status_old & SR_SRWD) {
+ dev_err(nor->dev,
+ "SR is write protected, can't update BP bits...\n");
+ return -EINVAL;
+ }
+
+ cr = spansion_read_cr(nor);
+ if (cr < 0)
+ return cr;
+
+ log_debug("SPI Protection: %s\n", (cr & CR_TB_SPAN) ? "bottom" : "top");
+
+ /* CR_TB is OTP, so we can't use 'top' protection if that is already set. */
+ can_be_top = !(cr & CR_TB_SPAN);
+
+ ret = spansion_nor_select_zone(nor, ofs, len, status_old, &use_top, 1);
+ /* Older protected blocks include the new requested block's */
+ if (ret <= 0)
+ return ret;
+
+ use_top = can_be_top;
+
+ /* lock_len: length of region that should end up locked */
+ if (use_top)
+ lock_len = nor->mtd.size - ofs;
+ else
+ lock_len = ofs + len;
+
+ sector_size = nor->sector_size;
+ n_sectors = (nor->size) / sector_size;
+
+ bp_slots = (1 << hweight8(mask)) - 2;
+ bp_slots_needed = ilog2(n_sectors);
+
+ if (bp_slots_needed > bp_slots)
+ sector_size <<= (bp_slots_needed - bp_slots);
+
+ pow = ilog2(lock_len) - ilog2(sector_size) + 1;
+ val = pow << shift;
+ sr_cr[0] = status_old & ~mask;
+ sr_cr[0] |= val;
+
+ sr_cr[1] = cr | (use_top ? 0 : CR_TB_SPAN);
+ ret = spansion_write_sr_cr(nor, sr_cr);
+ if (ret)
+ return ret;
+
+ /* Check that the bits got written as expected */
+ ret = read_sr(nor);
+ if (ret < 0)
+ return ret;
+
+ ret = spansion_read_cr(nor);
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+
+/**
+ * spansion_flash_unlock() - clear BP[012] write-protection.
+ * @nor: pointer to a 'struct spi_nor'.
+ * @ofs: offset from which to unlock memory.
+ * @len: number of bytes to unlock.
+ *
+ * Bits [234] of the Status Register are BP[012].
+ * Clear the corresponding BP status bits.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spansion_flash_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
+{
+ int ret, val;
+ u8 mask = SR_BP0 | SR_BP1 | SR_BP2;
+
+ val = read_sr(nor);
+ if (val < 0)
+ return val;
+
+ if (!(val & mask))
+ return 0;
+
+ write_enable(nor);
+
+ write_sr(nor, val & ~mask);
+
+ ret = spi_nor_wait_till_ready(nor);
+ if (ret)
+ return ret;
+
+ ret = write_disable(nor);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+#endif /* CONFIG_SPI_FLASH_SPANSION */
#endif /* CONFIG_SPI_FLASH_LOCK */
#ifdef CONFIG_SPI_FLASH_SOFT_RESET
@@ -5708,6 +6072,14 @@ int spi_nor_scan(struct spi_nor *nor)
}
#endif
+#if defined(CONFIG_SPI_FLASH_SPANSION)
+ if (JEDEC_MFR(info) == SNOR_MFR_SPANSION) {
+ nor->flash_lock = spansion_flash_lock;
+ nor->flash_unlock = spansion_flash_unlock;
+ nor->flash_is_unlocked = spansion_is_unlocked;
+ }
+#endif
+
#ifdef CONFIG_SPI_FLASH_SST
/*
* sst26 series block protection implementation differs from other
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 797f0f275a..07d6c4ff93 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -203,6 +203,7 @@
/* Configuration Register bits. */
#define CR_QUAD_EN_SPAN BIT(1) /* Spansion Quad I/O */
#define CR_TB_MX BIT(3) /* Macronix Top/Bottom protect */
+#define CR_TB_SPAN BIT(5) /* Spansion Top/Bottom protect */
/* Status Register 2 bits. */
#define SR2_QUAD_EN_BIT7 BIT(7)
--
2.27.0
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