[PATCH] mtd: spi-nor: Fix the read issue when addr_width is 4byte

[Venkatesh Yadav Abbarapu]

Fix the read issue for 4byte address width by passing the entire
length to the read function, split the memory of 16MB size banks
only when the address width is 3byte. Also update the size when
the configuration is stacked.

Fixes: 5d40b3d384 ("mtd: spi-nor: Add parallel and stacked memories support")
Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu at amd.com>
---
 drivers/mtd/spi/spi-nor-core.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index ec841fb13b..c37a9bce74 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -1580,6 +1580,7 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 	loff_t offset = from;
 	u32 read_len = 0;
 	u32 rem_bank_len = 0;
+	u32 stack_shift = 0;
 	u8 bank;
 	bool is_ofst_odd = false;
 
@@ -1593,18 +1594,20 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 	}
 
 	while (len) {
-		bank = (u32)from / SZ_16M;
-		if (nor->flags & SNOR_F_HAS_PARALLEL)
-			bank /= 2;
-
-		rem_bank_len = SZ_16M * (bank + 1);
-		if (nor->flags & SNOR_F_HAS_PARALLEL)
-			rem_bank_len *= 2;
-		rem_bank_len -= from;
-
+		if (nor->addr_width == 3) {
+			bank = (u32)from / SZ_16M;
+			if (nor->flags & SNOR_F_HAS_PARALLEL)
+				bank /= 2;
+
+			rem_bank_len = SZ_16M * (bank + 1);
+			if (nor->flags & SNOR_F_HAS_PARALLEL)
+				rem_bank_len *= 2;
+			rem_bank_len -= from;
+		}
 		offset = from;
 
 		if (nor->flags & SNOR_F_HAS_STACKED) {
+			stack_shift = 1;
 			if (offset >= (mtd->size / 2)) {
 				offset = offset - (mtd->size / 2);
 				nor->spi->flags |= SPI_XFER_U_PAGE;
@@ -1616,6 +1619,9 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 		if (nor->flags & SNOR_F_HAS_PARALLEL)
 			offset /= 2;
 
+		if (nor->addr_width == 4)
+			rem_bank_len = (mtd->size >> stack_shift) - offset;
+
 #ifdef CONFIG_SPI_FLASH_BAR
 		ret = write_bar(nor, offset);
 		if (ret < 0)
-- 
2.17.1