[PATCH v2 2/3] mtd: spi-nor: add 4bit block protection support

[Jungseung Lee <js07.lee@samsung.com>]

Currently, we are supporting block protection only for
flash chips with 3 block protection bits in the SR register.
This patch enables block protection support for some flash with
4 block protection bits(bp0-3).

Signed-off-by: Jungseung Lee <js07.lee@samsung.com>
---
v2 :
  Add sample table portion about 4bit block protection on the comment
  Trivial coding style change

 drivers/mtd/spi-nor/spi-nor.c | 127 +++++++++++++++++++++++++++++-----
 include/linux/mtd/spi-nor.h   |   8 +++
 2 files changed, 119 insertions(+), 16 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index e3da6a8654a8..76a3f0b9a7d6 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -238,6 +238,14 @@ struct flash_info {
 					 * status register. Must be used with
 					 * SPI_NOR_HAS_TB.
 					 */
+#define SPI_NOR_HAS_BP3		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_HAS_BP3.
+					 */
 
 	/* Part specific fixup hooks. */
 	const struct spi_nor_fixups *fixups;
@@ -1767,23 +1775,47 @@ static void stm_get_locked_range(struct spi_nor *nor, u8 sr, loff_t *ofs,
 	struct mtd_info *mtd = &nor->mtd;
 	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
 	u8 tb_mask = SR_TB_BIT5;
-	int pow;
+	u8 bp;
+	int pow = 0;
 
 	if (nor->flags & SNOR_F_HAS_SR_TB_BIT6)
 		tb_mask = SR_TB_BIT6;
 
-	if (!(sr & mask)) {
-		/* No protection */
-		*ofs = 0;
-		*len = 0;
+	if (nor->flags & SNOR_F_HAS_SR_BP3) {
+		u8 tmp;
+
+		if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6)
+			tmp = sr & (mask | SR_BP3_BIT6);
+		else
+			tmp = sr & (mask | SR_BP3_BIT5);
+
+		if (tmp & SR_BP3_BIT6)
+			tmp = (tmp & ~BIT(6)) | BIT(5);
+
+		bp = tmp >> SR_BP_SHIFT;
+		if (!bp) {
+			*ofs = 0;
+			*len = 0;
+			return;
+		}
+		if (bp <= ilog2(nor->n_sectors))
+			pow = ilog2(nor->n_sectors) + 1 - bp;
 	} else {
-		pow = ((sr & mask) ^ mask) >> SR_BP_SHIFT;
-		*len = mtd->size >> pow;
-		if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask)
+		bp = (sr & mask) >> SR_BP_SHIFT;
+		if (!bp) {
 			*ofs = 0;
-		else
-			*ofs = mtd->size - *len;
+			*len = 0;
+			return;
+		}
+		pow = bp ^ (mask >> SR_BP_SHIFT);
 	}
+
+	if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask)
+		*ofs = 0;
+	else
+		*ofs = mtd->size - *len;
+
+	*len = mtd->size >> pow;
 }
 
 /*
@@ -1823,7 +1855,7 @@ static int stm_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{0,1,2,3} 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)
@@ -1831,7 +1863,7 @@ static int stm_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
  * Support for the following is provided conditionally for some flash:
  *   - TB: top/bottom protect
  *
- * Sample table portion for 8MB flash (Winbond w25q64fw):
+ * Sample table portion for 8MB flash (Winbond w25q64fw / BP0-2):
  *
  *   SEC  |  TB   |  BP2  |  BP1  |  BP0  |  Prot Length  | Protected Portion
  *  --------------------------------------------------------------------------
@@ -1851,6 +1883,32 @@ static int stm_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, uint64_t len,
  *    0   |   1   |   1   |   0   |   1   |  2 MB         | Lower 1/4
  *    0   |   1   |   1   |   1   |   0   |  4 MB         | Lower 1/2
  *
+ * Sample table portion for 64MB flash (Micron n25q512ax3 / BP0-3):
+ *
+ *   TB   |  BP3  |  BP2  |  BP1  |  BP0  |  Prot Length  | Protected Portion
+ *  --------------------------------------------------------------------------
+ *    0   |   0   |   0   |   0   |   0   |  NONE         | NONE
+ *    0   |   0   |   0   |   0   |   1   |   64 KB       | Upper 1/1024
+ *    0   |   0   |   0   |   1   |   0   |  128 KB       | Upper 1/512
+ *    0   |   0   |   0   |   1   |   1   |  256 KB       | Upper 1/256
+ *   ...
+ *    0   |   1   |   0   |   0   |   1   |  16 MB        | Upper 1/4
+ *    0   |   1   |   0   |   1   |   0   |  32 MB        | Upper 1/2
+ *    0   |   1   |   0   |   1   |   1   |  64 MB        | ALL
+ *    0   |   1   |   1   |   0   |   0   |  64 MB        | ALL
+ *   ...
+ *  ------|-------|-------|-------|-------|---------------|-------------------
+ *    1   |   0   |   0   |   0   |   0   |   NONE        | NONE
+ *    1   |   0   |   0   |   0   |   1   |   64 KB       | Lower 1/1024
+ *    1   |   0   |   0   |   1   |   0   |  128 KB       | Lower 1/512
+ *    1   |   0   |   0   |   1   |   1   |  256 KB       | Lower 1/256
+ *   ...
+ *    1   |   1   |   0   |   0   |   1   |  16 MB        | Lower 1/4
+ *    1   |   1   |   0   |   1   |   0   |  32 MB        | Lower 1/2
+ *    1   |   1   |   0   |   1   |   1   |  64 MB        | ALL
+ *    1   |   1   |   1   |   0   |   0   |  64 MB        | ALL
+ *   ...
+ *
  * Returns negative on errors, 0 on success.
  */
 static int stm_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
@@ -1898,6 +1956,12 @@ static int stm_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;
 
+	if (nor->flags & SNOR_F_HAS_SR_BP3) {
+		if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6)
+			mask = mask | SR_BP3_BIT6;
+		else
+			mask = mask | SR_BP3_BIT5;
+	}
 	/*
 	 * Need smallest pow such that:
 	 *
@@ -1908,7 +1972,17 @@ static int stm_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	 *   pow = ceil(log2(size / len)) = log2(size) - floor(log2(len))
 	 */
 	pow = ilog2(mtd->size) - ilog2(lock_len);
-	val = mask - (pow << SR_BP_SHIFT);
+
+	if (nor->flags & SNOR_F_HAS_SR_BP3) {
+		val = ilog2(nor->n_sectors) + 1 - pow;
+		val = val << SR_BP_SHIFT;
+
+		if (val & BIT(5) && mask & SR_BP3_BIT6)
+			val = (val & ~BIT(5)) | BIT(6);
+	} else {
+		val = mask - (pow << SR_BP_SHIFT);
+	}
+
 	if (val & ~mask)
 		return -EINVAL;
 	/* Don't "lock" with no region! */
@@ -1983,6 +2057,13 @@ static int stm_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;
+
+	if (nor->flags & SNOR_F_HAS_SR_BP3) {
+		if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6)
+			mask = mask | SR_BP3_BIT6;
+		else
+			mask = mask | SR_BP3_BIT5;
+	}
 	/*
 	 * Need largest pow such that:
 	 *
@@ -1995,13 +2076,20 @@ static int stm_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	pow = ilog2(mtd->size) - order_base_2(lock_len);
 	if (lock_len == 0) {
 		val = 0; /* fully unlocked */
+	} else if (nor->flags & SNOR_F_HAS_SR_BP3) {
+		val = ilog2(nor->n_sectors) + 1 - pow;
+		val = val << SR_BP_SHIFT;
+
+		if (val & BIT(5) && mask & SR_BP3_BIT6)
+			val = (val & ~BIT(5)) | BIT(6);
 	} else {
 		val = mask - (pow << SR_BP_SHIFT);
-		/* Some power-of-two sizes are not supported */
-		if (val & ~mask)
-			return -EINVAL;
 	}
 
+	/* 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 */
@@ -4736,6 +4824,7 @@ static void spi_nor_info_init_params(struct spi_nor *nor)
 	/* Set SPI NOR sizes. */
 	params->size = (u64)info->sector_size * info->n_sectors;
 	params->page_size = info->page_size;
+	params->n_sectors = info->n_sectors;
 
 	if (!(info->flags & SPI_NOR_NO_FR)) {
 		/* Default to Fast Read for DT and non-DT platform devices. */
@@ -5192,6 +5281,11 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 		nor->flags |= SNOR_F_NO_OP_CHIP_ERASE;
 	if (info->flags & USE_CLSR)
 		nor->flags |= SNOR_F_USE_CLSR;
+	if (info->flags & SPI_NOR_HAS_BP3) {
+		nor->flags |= SNOR_F_HAS_SR_BP3;
+		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;
@@ -5199,6 +5293,7 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 	mtd->dev.parent = dev;
 	nor->page_size = params->page_size;
 	mtd->writebufsize = nor->page_size;
+	nor->n_sectors = params->n_sectors;
 
 	if (of_property_read_bool(np, "broken-flash-reset"))
 		nor->flags |= SNOR_F_BROKEN_RESET;
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 541c06d042e8..92d550501daf 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -129,7 +129,9 @@
 #define SR_BP1			BIT(3)	/* Block protect 1 */
 #define SR_BP2			BIT(4)	/* Block protect 2 */
 #define SR_TB_BIT5		BIT(5)	/* Top/Bottom protect */
+#define SR_BP3_BIT5		BIT(5)	/* Block protect 3 */
 #define SR_TB_BIT6		BIT(6)	/* Top/Bottom protect */
+#define SR_BP3_BIT6		BIT(6)	/* Block protect 3 */
 #define SR_SRWD			BIT(7)	/* SR write protect */
 /* Spansion/Cypress specific status bits */
 #define SR_E_ERR		BIT(5)
@@ -248,6 +250,8 @@ 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_SR_BP3	= BIT(12),
+	SNOR_F_HAS_SR_BP3_BIT6	= BIT(13),
 
 };
 
@@ -519,6 +523,7 @@ struct spi_nor_locking_ops {
  *
  * @size:		the flash memory density in bytes.
  * @page_size:		the page size of the SPI NOR flash memory.
+ * @n_sectors:		number of sectors
  * @hwcaps:		describes the read and page program hardware
  *			capabilities.
  * @reads:		read capabilities ordered by priority: the higher index
@@ -541,6 +546,7 @@ struct spi_nor_locking_ops {
 struct spi_nor_flash_parameter {
 	u64				size;
 	u32				page_size;
+	u16				n_sectors;
 
 	struct spi_nor_hwcaps		hwcaps;
 	struct spi_nor_read_command	reads[SNOR_CMD_READ_MAX];
@@ -573,6 +579,7 @@ struct flash_info;
  * @bouncebuf_size:	size of the bounce buffer
  * @info:		spi-nor part JDEC MFR id and other info
  * @page_size:		the page size of the SPI NOR
+ * @n_sector:		number of sectors
  * @addr_width:		number of address bytes
  * @erase_opcode:	the opcode for erasing a sector
  * @read_opcode:	the read opcode
@@ -599,6 +606,7 @@ struct spi_nor {
 	size_t			bouncebuf_size;
 	const struct flash_info	*info;
 	u32			page_size;
+	u16			n_sectors;
 	u8			addr_width;
 	u8			erase_opcode;
 	u8			read_opcode;
-- 
2.17.1


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