[PATCH v4 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 flash.

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>
---
 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 f522201d22a5..6d9c63ab6e51 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -1090,7 +1090,6 @@ 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 ||
@@ -1102,7 +1101,7 @@ 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;
@@ -1184,7 +1183,7 @@ 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;
@@ -1232,7 +1231,7 @@ 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! */
@@ -1269,7 +1268,7 @@ 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;
@@ -1319,7 +1318,7 @@ 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 67cdbed6611a..97f0c3a05f86 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -135,6 +135,8 @@
 
 #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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