[PATCH v4] mtd: spi-nor: Fix the spi_nor_read() when config SPI_STACKED_PARALLEL is enabled

[Venkatesh Yadav Abbarapu]

Update the spi_nor_read() function based on the config SPI_FLASH_BAR
and update the length and bank calculation by spliting the memory of
16MB size banks only when the address width is 3byte.
Fix the read issue for 4byte address width by passing the entire
length to the read function. 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>
---
Changes in v2:
- Update the nor read for parallel configuration and for other case
  keep the code as is.
- Fixed the commit description.
 - Tested the changes with s25fl128s flash  Zynq> sf probe 0 0 0
 SF: Detected s25fl128s with page size 256 Bytes, erase size 64 KiB,  total 16 MiB  Zynq> time sf erase 0x0 0x1000000;mw.b 0x8000 aabbccdd 0x1000000;time  Zynq> sf write 0x8000 0x0 0x1000000;mw.b 0x8008000 0x0 0x1000000;time  Zynq> sf read 0x8008000 0x0 0x1000000;cmp.b 0x8000 0x8008000 0x1000000
 SF: 16777216 bytes @ 0x0 Erased: OK
 
 time: 32.464 seconds
 device 0 whole chip
 SF: 16777216 bytes @ 0x0 Written: OK
 
 time: 15.515 seconds
 device 0 whole chip
 SF: 16777216 bytes @ 0x0 Read: OK
 
 time: 1.557 seconds
 Total of 16777216 byte(s) were the same

Changes in v3:
- Compile out the parallel code in spi_nor_erase() if the SPI_STACKED_PARALLEL
  is enabled. 

Changes in v4:
- Update the bank calculation only when SPL_FLASH_BAR is enabled.
---
 drivers/mtd/spi/spi-nor-core.c | 51 ++++++++++++++++++++--------------
 1 file changed, 30 insertions(+), 21 deletions(-)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index ec841fb13bd..a2ef37472d1 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -1130,17 +1130,19 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
 			goto erase_err;
 		}
 		offset = addr;
-		if (nor->flags & SNOR_F_HAS_PARALLEL)
-			offset /= 2;
-
-		if (nor->flags & SNOR_F_HAS_STACKED) {
-			if (offset >= (mtd->size / 2))
-				nor->spi->flags |= SPI_XFER_U_PAGE;
-			else
-				nor->spi->flags &= ~SPI_XFER_U_PAGE;
+		if (CONFIG_IS_ENABLED(SPI_STACKED_PARALLEL)) {
+			if (nor->flags & SNOR_F_HAS_PARALLEL)
+				offset /= 2;
+
+			if (nor->flags & SNOR_F_HAS_STACKED) {
+				if (offset >= (mtd->size / 2))
+					nor->spi->flags |= SPI_XFER_U_PAGE;
+				else
+					nor->spi->flags &= ~SPI_XFER_U_PAGE;
+			}
 		}
 #ifdef CONFIG_SPI_FLASH_BAR
-		ret = write_bar(nor, addr);
+		ret = write_bar(nor, offset);
 		if (ret < 0)
 			goto erase_err;
 #endif
@@ -1152,7 +1154,7 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
 		    !(nor->flags & SNOR_F_NO_OP_CHIP_ERASE)) {
 			ret = spi_nor_erase_chip(nor);
 		} else {
-			ret = spi_nor_erase_sector(nor, addr);
+			ret = spi_nor_erase_sector(nor, offset);
 		}
 		if (ret < 0)
 			goto erase_err;
@@ -1576,11 +1578,12 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 			size_t *retlen, u_char *buf)
 {
 	struct spi_nor *nor = mtd_to_spi_nor(mtd);
-	int ret;
 	loff_t offset = from;
-	u32 read_len = 0;
 	u32 rem_bank_len = 0;
+	u32 stack_shift = 0;
+	size_t read_len;
 	u8 bank;
+	int ret;
 	bool is_ofst_odd = false;
 
 	dev_dbg(nor->dev, "from 0x%08x, len %zd\n", (u32)from, len);
@@ -1593,18 +1596,22 @@ 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;
+		read_len = len;
+		offset = from;
 
-		rem_bank_len = SZ_16M * (bank + 1);
-		if (nor->flags & SNOR_F_HAS_PARALLEL)
-			rem_bank_len *= 2;
-		rem_bank_len -= from;
+		if (CONFIG_IS_ENABLED(SPI_FLASH_BAR)) {
+			bank = (u32)from / SZ_16M;
+			if (nor->flags & SNOR_F_HAS_PARALLEL)
+				bank /= 2;
 
-		offset = from;
+			rem_bank_len = SZ_16M * (bank + 1);
+			if (nor->flags & SNOR_F_HAS_PARALLEL)
+				rem_bank_len *= 2;
+			rem_bank_len -= 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;
@@ -1613,6 +1620,9 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 			}
 		}
 
+		if (nor->addr_width == 4)
+			rem_bank_len = (mtd->size >> stack_shift) - offset;
+
 		if (nor->flags & SNOR_F_HAS_PARALLEL)
 			offset /= 2;
 
@@ -1621,7 +1631,6 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 		if (ret < 0)
 			return log_ret(ret);
 #endif
-
 		if (len < rem_bank_len)
 			read_len = len;
 		else
-- 
2.34.1