[PATCH v5 3/5] mtd: spi-nor: introduce SR_BP_SHIFT define

[Jungseung Lee <js07.lee@xxxxxxxxxxx>]

The shift variable of SR_BP is conclusive because the first bit of SR_BP
is fixed on known flashes.

Introduce SR_BP_SHIFT define, and let them used by stm_* functions
to replace ffs operation to get shift value.

Signed-off-by: Jungseung Lee <js07.lee@xxxxxxxxxxx>
---
v5:
 - remake patch based on latest spi-nor/next tree
 - Fix commit log

 drivers/mtd/spi-nor/spi-nor.c | 11 +++++------
 include/linux/mtd/spi-nor.h   |  2 ++
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 5bed03e61bd0..84522c825ab5 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -1412,7 +1412,6 @@ 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 mask_tb = SR_TB_BIT5;
-	int shift = ffs(mask) - 1;
 	int pow;
 
 	if (JEDEC_MFR(nor->info) == SNOR_MFR_WINBOND ||
@@ -1424,7 +1423,7 @@ static void stm_get_locked_range(struct spi_nor *nor, u8 sr, loff_t *ofs,
 		*ofs = 0;
 		*len = 0;
 	} else {
-		pow = ((sr & mask) ^ mask) >> shift;
+		pow = ((sr & mask) ^ mask) >> SR_BP_SHIFT;
 		*len = mtd->size >> pow;
 		if (nor->flags & SNOR_F_HAS_SR_TB && sr & mask_tb)
 			*ofs = 0;
@@ -1506,7 +1505,7 @@ static int stm_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	int status_old, status_new;
 	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
 	u8 mask_tb = SR_TB_BIT5;
-	u8 shift = ffs(mask) - 1, pow, val;
+	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;
@@ -1554,7 +1553,7 @@ 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 << shift);
+	val = mask - (pow << SR_BP_SHIFT);
 	if (val & ~mask)
 		return -EINVAL;
 	/* Don't "lock" with no region! */
@@ -1591,7 +1590,7 @@ static int stm_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	int status_old, status_new;
 	u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
 	u8 mask_tb = SR_TB_BIT5;
-	u8 shift = ffs(mask) - 1, pow, val;
+	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;
@@ -1641,7 +1640,7 @@ static int stm_unlock(struct spi_nor *nor, loff_t ofs, uint64_t len)
 	if (lock_len == 0) {
 		val = 0; /* fully unlocked */
 	} else {
-		val = mask - (pow << shift);
+		val = mask - (pow << SR_BP_SHIFT);
 		/* Some power-of-two sizes are not supported */
 		if (val & ~mask)
 			return -EINVAL;
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 654992a829bd..abbe5f915410 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -136,6 +136,8 @@
 
 #define SR_QUAD_EN_MX		BIT(6)	/* Macronix Quad I/O */
 
+#define SR_BP_SHIFT		2
+
 /* Enhanced Volatile Configuration Register bits */
 #define EVCR_QUAD_EN_MICRON	BIT(7)	/* Micron Quad I/O */
 
-- 
2.17.1


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