mtd: spi-nor: Add SR 4bit block protection support

Currently we are supporting block protection only for flash chips with
3 block protection bits (BP0-2) in the SR register.

Enable block protection support for flashes with 4 block protection bits
(BP0-3).

Add a flash_info flag for flashes that describe 4 block protection bits.
Add another flash_info flag for flashes in which BP3 bit is not adjacent
to the BP0-2 bits.

Tested with a n25q512ax3 (BP0-3) and w25q128 (BP0-2).

Signed-off-by: Jungseung Lee <js07.lee@samsung.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Tested-by: Michael Walle <michael@walle.cc>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

drivers/mtd/spi-nor/core.c

@@ -1536,13 +1536,34 @@ erase_err:
 	return ret;
 }
 
+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 = SR_BP2 | SR_BP1 | SR_BP0;
+	u8 mask = spi_nor_get_sr_bp_mask(nor);
 
 	/* Reserved one for "protect none" and one for "protect all". */
-	bp_slots = (mask >> SR_BP_SHIFT) + 1 - 2;
+	bp_slots = (1 << hweight8(mask)) - 2;
 	bp_slots_needed = ilog2(nor->info->n_sectors);
 
 	if (bp_slots_needed > bp_slots)
@@ -1557,12 +1578,14 @@ static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs,
 {
 	struct mtd_info *mtd = &nor->mtd;
 	u64 min_prot_len;
-	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
+	u8 mask = spi_nor_get_sr_bp_mask(nor);
-	u8 tb_mask = SR_TB_BIT5;
+	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
-	u8 bp = (sr & mask) >> SR_BP_SHIFT;
+	u8 bp, val = sr & mask;
 
-	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
+	if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6)
-		tb_mask = SR_TB_BIT6;
+		val = (val & ~SR_BP3_BIT6) | SR_BP3;
+
+	bp = val >> SR_BP_SHIFT;
 
 	if (!bp) {
 		/* No protection */
@@ -1620,7 +1643,8 @@ static int spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
 
 /*
  * Lock a region of the flash. Compatible with ST Micro and similar flash.
- * Supports the block protection bits BP{0,1,2} in the status register
+ * 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)
@@ -1655,8 +1679,8 @@ 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 mask = spi_nor_get_sr_bp_mask(nor);
-	u8 tb_mask = SR_TB_BIT5;
+	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;
@@ -1693,9 +1717,6 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	else
 		lock_len = ofs + len;
 
-	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
-		tb_mask = SR_TB_BIT6;
-
 	if (lock_len == mtd->size) {
 		val = mask;
 	} else {
@@ -1703,6 +1724,9 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 		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;
 
@@ -1740,8 +1764,8 @@ 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 mask = spi_nor_get_sr_bp_mask(nor);
-	u8 tb_mask = SR_TB_BIT5;
+	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;
@@ -1778,9 +1802,6 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	else
 		lock_len = ofs;
 
-	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
-		tb_mask = SR_TB_BIT6;
-
 	if (lock_len == 0) {
 		val = 0; /* fully unlocked */
 	} else {
@@ -1788,6 +1809,9 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 		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;
@@ -3147,6 +3171,12 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 	if (info->flags & USE_CLSR)
 		nor->flags |= SNOR_F_USE_CLSR;
 
+	if (info->flags & SPI_NOR_4BIT_BP) {
+		nor->flags |= SNOR_F_HAS_4BIT_BP;
+		if (info->flags & SPI_NOR_BP3_SR_BIT6)
+			nor->flags |= SNOR_F_HAS_SR_BP3_BIT6;
+	}
+
 	if (info->flags & SPI_NOR_NO_ERASE)
 		mtd->flags |= MTD_NO_ERASE;
 

drivers/mtd/spi-nor/core.h

@@ -24,6 +24,8 @@ enum spi_nor_option_flags {
 	SNOR_F_HAS_16BIT_SR	= BIT(9),
 	SNOR_F_NO_READ_CR	= BIT(10),
 	SNOR_F_HAS_SR_TB_BIT6	= BIT(11),
+	SNOR_F_HAS_4BIT_BP      = BIT(12),
+	SNOR_F_HAS_SR_BP3_BIT6  = BIT(13),
 };
 
 struct spi_nor_read_command {
@@ -301,6 +303,14 @@ struct flash_info {
 					 * status register. Must be used with
 					 * SPI_NOR_HAS_TB.
 					 */
+#define SPI_NOR_4BIT_BP		BIT(17) /*
+					 * Flash SR has 4 bit fields (BP0-3)
+					 * for block protection.
+					 */
+#define SPI_NOR_BP3_SR_BIT6	BIT(18) /*
+					 * BP3 is bit 6 of status register.
+					 * Must be used with SPI_NOR_4BIT_BP.
+					 */
 
 	/* Part specific fixup hooks. */
 	const struct spi_nor_fixups *fixups;

include/linux/mtd/spi-nor.h

@@ -111,7 +111,9 @@
 #define SR_BP0			BIT(2)	/* Block protect 0 */
 #define SR_BP1			BIT(3)	/* Block protect 1 */
 #define SR_BP2			BIT(4)	/* Block protect 2 */
+#define SR_BP3			BIT(5)	/* Block protect 3 */
 #define SR_TB_BIT5		BIT(5)	/* Top/Bottom protect */
+#define SR_BP3_BIT6		BIT(6)	/* Block protect 3 */
 #define SR_TB_BIT6		BIT(6)	/* Top/Bottom protect */
 #define SR_SRWD			BIT(7)	/* SR write protect */
 /* Spansion/Cypress specific status bits */