[PATCH v2] mtd: spi-nor: Fixup page size for S25FS-S

[Alexander A Sverdlin <alexander.sverdlin@xxxxxxxxx>]

From: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx>

Spansion S25FS-S family has an issue in Basic Flash Parameter Table:
DWORD-11 bits 7-4 specify write page size 512 bytes. In reality this
is configurable in the non-volatile CR3NV register and even factory
default configuration is "wrap at 256 bytes". So blind relying on BFPT
breaks write operation on these Flashes.

All this story is vendor-specific, so add the corresponding fixup hook
which first restores the safe page size of 256 bytes from
struct flash_info but checks is more performant 512 bytes configuration
is active and adjusts the page_size accordingly.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: f384b352c ("mtd: spi-nor: parse Serial Flash Discoverable Parameters (SFDP) tables")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx>
---
Changelog:
v2: Thankfully rebased on the hint from John Garry

 drivers/mtd/spi-nor/spi-nor.c | 39 +++++++++++++++++++++++++++++++++++++--
 include/linux/mtd/spi-nor.h   |  5 +++++
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 928a660..c0a5041 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -2302,6 +2302,39 @@ static struct spi_nor_fixups gd25q256_fixups = {
 	.default_init = gd25q256_default_init,
 };
 
+/* Spansion S25FS-S SFDP workarounds */
+static int s25fs_s_post_bfpt_fixups(struct spi_nor *nor,
+	const struct sfdp_parameter_header *bfpt_header,
+	const struct sfdp_bfpt *bfpt,
+	struct spi_nor_flash_parameter *params)
+{
+	const struct flash_info *info = nor->info;
+	u8 read_opcode, buf;
+	int ret;
+
+	/* Default is safe */
+	params->page_size = info->page_size;
+
+	/*
+	 * But is the chip configured for more performant 512 bytes write page
+	 * size?
+	 */
+	read_opcode = nor->read_opcode;
+
+	nor->read_opcode = SPINOR_OP_RDAR;
+	ret = nor->read(nor, SPINOR_REG_CR3V, 1, &buf);
+	if (!ret && (buf & CR3V_02H_V))
+		params->page_size = 512;
+
+	nor->read_opcode = read_opcode;
+
+	return ret;
+}
+
+static const struct spi_nor_fixups s25fs_s_fixups = {
+	.post_bfpt = s25fs_s_post_bfpt_fixups,
+};
+
 /* NOTE: double check command sets and memory organization when you add
  * more nor chips.  This current list focusses on newer chips, which
  * have been converging on command sets which including JEDEC ID.
@@ -2536,7 +2569,8 @@ static const struct flash_info spi_nor_ids[] = {
 			SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ | USE_CLSR) },
 	{ "s25fl128s1", INFO6(0x012018, 0x4d0180, 64 * 1024, 256,
 			SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ | USE_CLSR) },
-	{ "s25fl256s0", INFO(0x010219, 0x4d00, 256 * 1024, 128, USE_CLSR) },
+	{ "s25fl256s0", INFO(0x010219, 0x4d00, 256 * 1024, 128, USE_CLSR)
+			.fixups = &s25fs_s_fixups, },
 	{ "s25fl256s1", INFO(0x010219, 0x4d01,  64 * 1024, 512, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ | USE_CLSR) },
 	{ "s25fl512s",  INFO6(0x010220, 0x4d0080, 256 * 1024, 256,
 			SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
@@ -2546,7 +2580,8 @@ static const struct flash_info spi_nor_ids[] = {
 	{ "s25sl12800", INFO(0x012018, 0x0300, 256 * 1024,  64, 0) },
 	{ "s25sl12801", INFO(0x012018, 0x0301,  64 * 1024, 256, 0) },
 	{ "s25fl129p0", INFO(0x012018, 0x4d00, 256 * 1024,  64, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ | USE_CLSR) },
-	{ "s25fl129p1", INFO(0x012018, 0x4d01,  64 * 1024, 256, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ | USE_CLSR) },
+	{ "s25fl129p1", INFO(0x012018, 0x4d01,  64 * 1024, 256, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ | USE_CLSR)
+			.fixups = &s25fs_s_fixups, },
 	{ "s25sl004a",  INFO(0x010212,      0,  64 * 1024,   8, 0) },
 	{ "s25sl008a",  INFO(0x010213,      0,  64 * 1024,  16, 0) },
 	{ "s25sl016a",  INFO(0x010214,      0,  64 * 1024,  32, 0) },
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 5abd91c..7ce3e79 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -116,6 +116,7 @@
 /* Used for Spansion flashes only. */
 #define SPINOR_OP_BRWR		0x17	/* Bank register write */
 #define SPINOR_OP_CLSR		0x30	/* Clear status register 1 */
+#define SPINOR_OP_RDAR		0x65	/* Read Any Register */
 
 /* Used for Micron flashes only. */
 #define SPINOR_OP_RD_EVCR      0x65    /* Read EVCR register */
@@ -150,6 +151,10 @@
 #define SR2_QUAD_EN_BIT1	BIT(1)
 #define SR2_QUAD_EN_BIT7	BIT(7)
 
+/* Used for Spansion flashes RDAR command only. */
+#define SPINOR_REG_CR3V		0x800004
+#define CR3V_02H_V		BIT(4)	/* Page Buffer Wrap */
+
 /* Supported SPI protocols */
 #define SNOR_PROTO_INST_MASK	GENMASK(23, 16)
 #define SNOR_PROTO_INST_SHIFT	16
-- 
2.4.6


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