[PATCH] mtd: spi-nor: Recover from Spansion/Cypress errors

[Alexander Sverdlin]

S25FL{128|256|512}S datasheets say:
"When P_ERR or E_ERR bits are set to one, the WIP bit will remain set to
one indicating the device remains busy and unable to receive new operation
commands. A Clear Status Register (CLSR) command must be received to return
the device to standby mode."

Current spi-nor code works until first error occurs, but write/erase errors
are not just rare hardware failures, they also occur if user tries to flash
write-protected areas. After such attempt no SPI command can be executed
any more and even read fails. This patch adds support for P_ERR and E_ERR
bits in Status Register 1 (so that operation fails immediately and not
after a long timeout) and proper recovery from the error condition.

Tested on Spansion S25FS128S, which is supported by S25FL129P entry.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin at nokia.com>
---
 drivers/mtd/spi-nor/spi-nor.c | 29 +++++++++++++++++++++--------
 include/linux/mtd/spi-nor.h   |  5 +++++
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index dea8c9c..efb3519 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -86,6 +86,7 @@ struct flash_info {
 					 * to support memory size above 128Mib.
 					 */
 #define NO_CHIP_ERASE		BIT(12) /* Chip does not support chip erase */
+#define USE_CLSR		BIT(13)	/* use CLSR command */
 };
 
 #define JEDEC_MFR(info)	((info)->id[0])
@@ -320,8 +321,18 @@ static inline int spi_nor_sr_ready(struct spi_nor *nor)
 	int sr = read_sr(nor);
 	if (sr < 0)
 		return sr;
-	else
-		return !(sr & SR_WIP);
+
+	if (nor->flags & SNOR_F_USE_CLSR && sr & (SR_E_ERR | SR_P_ERR)) {
+		if (sr & SR_E_ERR)
+			dev_err(nor->dev, "Erase Error occurred\n");
+		else
+			dev_err(nor->dev, "Programming Error occurred\n");
+
+		nor->write_reg(nor, SPINOR_OP_CLSR, NULL, 0);
+		return -EIO;
+	}
+
+	return !(sr & SR_WIP);
 }
 
 static inline int spi_nor_fsr_ready(struct spi_nor *nor)
@@ -1053,15 +1064,15 @@ static const struct flash_info spi_nor_ids[] = {
 	 */
 	{ "s25sl032p",  INFO(0x010215, 0x4d00,  64 * 1024,  64, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
 	{ "s25sl064p",  INFO(0x010216, 0x4d00,  64 * 1024, 128, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
-	{ "s25fl256s0", INFO(0x010219, 0x4d00, 256 * 1024, 128, 0) },
-	{ "s25fl256s1", INFO(0x010219, 0x4d01,  64 * 1024, 512, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
-	{ "s25fl512s",  INFO(0x010220, 0x4d00, 256 * 1024, 256, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
+	{ "s25fl256s0", INFO(0x010219, 0x4d00, 256 * 1024, 128, USE_CLSR) },
+	{ "s25fl256s1", INFO(0x010219, 0x4d01,  64 * 1024, 512, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ | USE_CLSR) },
+	{ "s25fl512s",  INFO(0x010220, 0x4d00, 256 * 1024, 256, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ | USE_CLSR) },
 	{ "s70fl01gs",  INFO(0x010221, 0x4d00, 256 * 1024, 256, 0) },
 	{ "s25sl12800", INFO(0x012018, 0x0300, 256 * 1024,  64, 0) },
 	{ "s25sl12801", INFO(0x012018, 0x0301,  64 * 1024, 256, 0) },
-	{ "s25fl128s",	INFO6(0x012018, 0x4d0180, 64 * 1024, 256, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
-	{ "s25fl129p0", INFO(0x012018, 0x4d00, 256 * 1024,  64, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
-	{ "s25fl129p1", INFO(0x012018, 0x4d01,  64 * 1024, 256, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
+	{ "s25fl128s",  INFO6(0x012018, 0x4d0180, 64 * 1024, 256, SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ | USE_CLSR) },
+	{ "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) },
 	{ "s25sl004a",  INFO(0x010212,      0,  64 * 1024,   8, 0) },
 	{ "s25sl008a",  INFO(0x010213,      0,  64 * 1024,  16, 0) },
 	{ "s25sl016a",  INFO(0x010214,      0,  64 * 1024,  32, 0) },
@@ -1641,6 +1652,8 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 		nor->flags |= SNOR_F_HAS_SR_TB;
 	if (info->flags & NO_CHIP_ERASE)
 		nor->flags |= SNOR_F_NO_OP_CHIP_ERASE;
+	if (info->flags & USE_CLSR)
+		nor->flags |= SNOR_F_USE_CLSR;
 
 #ifdef CONFIG_MTD_SPI_NOR_USE_4K_SECTORS
 	/* prefer "small sector" erase if possible */
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index f2a7180..0dc6c34 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -93,6 +93,7 @@
 
 /* Used for Spansion flashes only. */
 #define SPINOR_OP_BRWR		0x17	/* Bank register write */
+#define SPINOR_OP_CLSR		0x30	/* Clear status register 1 */
 
 /* Used for Micron flashes only. */
 #define SPINOR_OP_RD_EVCR      0x65    /* Read EVCR register */
@@ -107,6 +108,9 @@
 #define SR_BP2			BIT(4)	/* Block protect 2 */
 #define SR_TB			BIT(5)	/* Top/Bottom protect */
 #define SR_SRWD			BIT(7)	/* SR write protect */
+/* Spansion/Cypress specific status bits */
+#define SR_E_ERR		BIT(5)
+#define SR_P_ERR		BIT(6)
 
 #define SR_QUAD_EN_MX		BIT(6)	/* Macronix Quad I/O */
 
@@ -141,6 +145,7 @@ enum spi_nor_option_flags {
 	SNOR_F_NO_OP_CHIP_ERASE	= BIT(2),
 	SNOR_F_S3AN_ADDR_DEFAULT = BIT(3),
 	SNOR_F_READY_XSR_RDY	= BIT(4),
+	SNOR_F_USE_CLSR		= BIT(5),
 };
 
 /**
-- 
2.4.6