mtd: spi-nor: Recover from Spansion/Cypress errors

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@nokia.com>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>

include/linux/mtd/spi-nor.h

@@ -105,6 +105,7 @@
 
 /* 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 */
@@ -119,6 +120,9 @@
 #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 */
 
@@ -224,6 +228,7 @@ 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),
 };
 
 /**