[PATCH v2 29/30] mtd: spi-nor: Add support for locking on GIGADEVICE nor flashes

Tejas Bhumkar tejas.arvind.bhumkar at amd.com
Wed Dec 6 10:31:40 CET 2023


From: Venkatesh Yadav Abbarapu <venkatesh.abbarapu at amd.com>

GIGADEVICE nor flashes provide block protection support using
BP0, BP1, BP2, BP3 & TB bits in status register.

BP(Block Protection) bits defines memory to be software
protected against PROGRAM or ERASE operations. When one or more
block protect bits are set to 1, a designated memory area is
protected from PROGRAM and ERASE operations. TB(Top/Bottom) bit
determines whether the protected memory area defined by the block
protect bits starts from the top or bottom of the memory array.

Used bottom/top protect to test 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 | 309 +++++++++++++++++++++++++++++++++
 include/linux/mtd/spi-nor.h    |   2 +
 2 files changed, 311 insertions(+)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 3bf1e5471b..3e2491cc3e 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -5164,6 +5164,307 @@ static int issi_flash_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	return ret;
 }
 #endif /* CONFIG_SPI_FLASH_ISSI */
+
+#if defined(CONFIG_SPI_FLASH_GIGADEVICE)
+static void giga_get_locked_range(struct spi_nor *nor, u8 sr, loff_t *ofs,
+				  uint64_t *len)
+{
+	struct mtd_info *mtd = &nor->mtd;
+	int shift = 0;
+	int pow;
+	u8 mask = SR_BP0 | SR_BP1 | SR_BP2 | SR_BP3_GIGA;
+	u32 sector_size;
+
+	sector_size = nor->sector_size;
+	if (nor->flags & SNOR_F_HAS_PARALLEL)
+		sector_size >>= 1;
+
+	shift = ffs(mask) - 1;
+
+	if (!(sr & mask)) {
+		/* No protection */
+		*ofs = 0;
+		*len = 0;
+	} else {
+		pow = ((sr & mask) >> shift) - 1;
+		*len = sector_size << pow;
+		if (*len > mtd->size)
+			*len = mtd->size;
+		/* GIGA device's have top/bottom select bit in status reg */
+		if (nor->flags & SNOR_F_HAS_SR_TB && sr & SR_TB_GIGA)
+			*ofs = 0;
+		else
+			*ofs = mtd->size - *len;
+	}
+}
+
+/**
+ * giga_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 giga_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;
+
+	giga_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);
+}
+
+/**
+ * giga_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 giga_is_locked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
+			     u8 sr)
+{
+	return giga_check_lock_status_sr(nor, ofs, len, sr, true);
+}
+
+/**
+ * giga_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 giga_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
+			       u8 sr)
+{
+	return giga_check_lock_status_sr(nor, ofs, len, sr, false);
+}
+
+/**
+ * giga_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 giga_is_unlocked(struct spi_nor *nor, loff_t ofs, uint64_t len)
+{
+	int sr;
+
+	sr = read_sr(nor);
+	if (sr < 0)
+		return sr;
+
+	return giga_check_lock_status_sr(nor, ofs, len, sr, false);
+}
+
+/**
+ * giga_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 giga_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 (giga_is_locked_sr(nor, ofs, len, sr))
+			return 0;
+
+		/*
+		 * If anything below us is unlocked, we can't use 'bottom'
+		 * protection.
+		 */
+		if (!giga_is_locked_sr(nor, 0, ofs, sr))
+			can_be_bottom = false;
+
+		/*
+		 * If anything above us is unlocked, we can't use 'top'
+		 * protection.
+		 */
+		if (!giga_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 (giga_is_unlocked_sr(nor, ofs, len, sr))
+			return 0;
+
+		/*
+		 * If anything below us is locked, we can't use 'top'
+		 * protection
+		 */
+		if (!giga_is_unlocked_sr(nor, 0, ofs, sr))
+			can_be_top = false;
+
+		/*
+		 * If anything above us is locked, we can't use 'bottom'
+		 * protection
+		 */
+		if (!giga_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;
+}
+
+/**
+ * giga_flash_lock() - set BP[0123] 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{0,1,2,3} in status register
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int giga_flash_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
+{
+	int status_old, status_new, blk_prot;
+	loff_t lock_len;
+	u8 pow, ret, shift;
+	bool use_top = false;
+	u8 mask = SR_BP0 | SR_BP1 | SR_BP2 | SR_BP3_GIGA;
+
+	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;
+	}
+
+	log_debug("SPI Protection: %s\n", (status_old & SR_TB_GIGA) ? "bottom" : "top");
+
+	ret = giga_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;
+
+	/* lock_len: length of region that should end up locked */
+	if (use_top)
+		lock_len = nor->mtd.size - ofs;
+	else
+		lock_len = ofs + len;
+
+	pow = order_base_2(lock_len);
+	blk_prot = mask & (((pow + 1) & 0xf) << shift);
+	if (lock_len <= 0) {
+		dev_err(nor->dev, "invalid Length to protect");
+		return -EINVAL;
+	}
+
+	status_new = status_old | blk_prot;
+	if (!use_top)
+		status_new |= SR_TB_GIGA;
+	else
+		status_new &= ~SR_TB_GIGA;
+
+	if (status_old == status_new)
+		return 0;
+
+	return write_sr_and_check(nor, status_new, mask);
+}
+
+/**
+ * giga_flash_unlock() - clear BP[0123] write-protection.
+ * @nor: pointer to a 'struct spi_nor'.
+ * @ofs: offset from which to unlock memory.
+ * @len: number of bytes to unlock.
+ *
+ * Bits [2345] of the Status Register are BP[0123].
+ * Clear the corresponding BP status bits.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int giga_flash_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
+{
+	int ret, val;
+	u8 mask = SR_BP0 | SR_BP1 | SR_BP2 | SR_BP3_GIGA;
+
+	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;
+
+	ret = read_sr(nor);
+	if (ret > 0 && !(ret & mask)) {
+		dev_info(nor->dev, "block protect bits cleared SR: 0x%x\n",
+			 ret);
+		ret = 0;
+	}
+	return ret;
+}
+#endif /* CONFIG_SPI_FLASH_GIGADEVICE */
 #endif /* CONFIG_SPI_FLASH_LOCK */
 
 #ifdef CONFIG_SPI_FLASH_SOFT_RESET
@@ -5399,6 +5700,14 @@ int spi_nor_scan(struct spi_nor *nor)
 	}
 #endif
 
+#if defined(CONFIG_SPI_FLASH_GIGADEVICE)
+	if (JEDEC_MFR(info) == SNOR_MFR_GIGADEVICE) {
+		nor->flash_lock = giga_flash_lock;
+		nor->flash_unlock = giga_flash_unlock;
+		nor->flash_is_unlocked = giga_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 9a560d94a2..797f0f275a 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -172,6 +172,8 @@
 #define SR_BP3			BIT(6)  /* Block protect 3 */
 #define SR_BP3_MX		BIT(5)	/* Block protect 3 (Macronix) */
 #define SR_BP3_ISSI		BIT(5)	/* Block protect 3 (ISSI) */
+#define SR_TB_GIGA		BIT(6)  /* Top/Bottom protect (GIGADEVICE)*/
+#define SR_BP3_GIGA		BIT(5)	/* Block protect 3 (GIGADEVICE) */
 #define SR_TB			BIT(5)	/* Top/Bottom protect */
 #define SR_SRWD			BIT(7)	/* SR write protect */
 
-- 
2.27.0



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