[PATCH] mtd: spi-nor: sst: Factor out common write operation to `sst_nor_write_data()`

[Csókás, Bence]

Writing to the Flash in `sst_nor_write()` is a 3-step process:
first an optional one-byte write to get 2-byte-aligned, then the
bulk of the data is written out in vendor-specific 2-byte writes.
Finally, if there's a byte left over, another one-byte write.
This was implemented 3 times in the body of `sst_nor_write()`.
To reduce code duplication, factor out these sub-steps to their
own function.

Signed-off-by: Csókás, Bence <csokas.bence at prolan.hu>
---

Notes:
    RFC: I'm thinking of removing SPINOR_OP_BP in favor of
    SPINOR_OP_PP (they have the same value). SPINOR_OP_PP
    is the "standard" name for the elementary unit-sized
    (1 byte, in the case of NOR) write operation. I find it
    confusing to have two names for the same operation,
    so in a followup I plan to remove the vendor-specific
    name in favor of the standard one.

 drivers/mtd/spi-nor/sst.c | 39 +++++++++++++++++++--------------------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/drivers/mtd/spi-nor/sst.c b/drivers/mtd/spi-nor/sst.c
index 180b7390690c..fec71689e644 100644
--- a/drivers/mtd/spi-nor/sst.c
+++ b/drivers/mtd/spi-nor/sst.c
@@ -167,6 +167,21 @@ static const struct flash_info sst_nor_parts[] = {
 	}
 };
 
+static int sst_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
+			const u_char *buf)
+{
+	u8 op = (len == 1) ? SPINOR_OP_BP : SPINOR_OP_AAI_WP;
+	int ret;
+
+	nor->program_opcode = op;
+	ret = spi_nor_write_data(nor, to, 1, buf);
+	if (ret < 0)
+		return ret;
+	WARN(ret != len, "While writing %i byte written %i bytes\n", len, ret);
+
+	return spi_nor_wait_till_ready(nor);
+}
+
 static int sst_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 			 size_t *retlen, const u_char *buf)
 {
@@ -188,16 +203,10 @@ static int sst_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 
 	/* Start write from odd address. */
 	if (to % 2) {
-		nor->program_opcode = SPINOR_OP_BP;
-
 		/* write one byte. */
-		ret = spi_nor_write_data(nor, to, 1, buf);
+		ret = sst_nor_write_data(nor, to, 1, buf);
 		if (ret < 0)
 			goto out;
-		WARN(ret != 1, "While writing 1 byte written %i bytes\n", ret);
-		ret = spi_nor_wait_till_ready(nor);
-		if (ret)
-			goto out;
 
 		to++;
 		actual++;
@@ -205,16 +214,11 @@ static int sst_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 
 	/* Write out most of the data here. */
 	for (; actual < len - 1; actual += 2) {
-		nor->program_opcode = SPINOR_OP_AAI_WP;
-
 		/* write two bytes. */
-		ret = spi_nor_write_data(nor, to, 2, buf + actual);
+		ret = sst_nor_write_data(nor, to, 2, buf + actual);
 		if (ret < 0)
 			goto out;
-		WARN(ret != 2, "While writing 2 bytes written %i bytes\n", ret);
-		ret = spi_nor_wait_till_ready(nor);
-		if (ret)
-			goto out;
+
 		to += 2;
 		nor->sst_write_second = true;
 	}
@@ -234,14 +238,9 @@ static int sst_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 		if (ret)
 			goto out;
 
-		nor->program_opcode = SPINOR_OP_BP;
-		ret = spi_nor_write_data(nor, to, 1, buf + actual);
+		ret = sst_nor_write_data(nor, to, 1, buf + actual);
 		if (ret < 0)
 			goto out;
-		WARN(ret != 1, "While writing 1 byte written %i bytes\n", ret);
-		ret = spi_nor_wait_till_ready(nor);
-		if (ret)
-			goto out;
 
 		actual += 1;
 
-- 
2.34.1