sf: Fix quad bit set for micron devices

Setting up quad bit for micron devices need to do the
same way as other flash devices like spansion, winbond
etc does using enhanced volatile config register so this
patch adds this support instead of printing "QEB is volatile"

Cc: Simon Glass <sjg@chromium.org>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Peter Pan <peterpandong@micron.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Jagan Teki <jteki@openedev.com>

drivers/mtd/spi/sf_internal.h

@@ -77,6 +77,7 @@ enum spi_nor_option_flags {
 #define CMD_WRITE_DISABLE		0x04
 #define CMD_WRITE_ENABLE		0x06
 #define CMD_QUAD_PAGE_PROGRAM		0x32
+#define CMD_WRITE_EVCR			0x61
 
 /* Read commands */
 #define CMD_READ_ARRAY_SLOW		0x03
@@ -90,6 +91,7 @@ enum spi_nor_option_flags {
 #define CMD_READ_STATUS1		0x35
 #define CMD_READ_CONFIG			0x35
 #define CMD_FLAG_STATUS			0x70
+#define CMD_READ_EVCR			0x65
 
 /* Bank addr access commands */
 #ifdef CONFIG_SPI_FLASH_BAR
@@ -104,6 +106,7 @@ enum spi_nor_option_flags {
 #define STATUS_QEB_WINSPAN		BIT(1)
 #define STATUS_QEB_MXIC			BIT(6)
 #define STATUS_PEC			BIT(7)
+#define STATUS_QEB_MICRON		BIT(7)
 #define SR_BP0				BIT(2)  /* Block protect 0 */
 #define SR_BP1				BIT(3)  /* Block protect 1 */
 #define SR_BP2				BIT(4)  /* Block protect 2 */

drivers/mtd/spi/spi_flash.c

@@ -111,6 +111,37 @@ static int write_cr(struct spi_flash *flash, u8 wc)
 }
 #endif
 
+#ifdef CONFIG_SPI_FLASH_STMICRO
+static int read_evcr(struct spi_flash *flash, u8 *evcr)
+{
+	int ret;
+	const u8 cmd = CMD_READ_EVCR;
+
+	ret = spi_flash_read_common(flash, &cmd, 1, evcr, 1);
+	if (ret < 0) {
+		debug("SF: error reading EVCR\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int write_evcr(struct spi_flash *flash, u8 evcr)
+{
+	u8 cmd;
+	int ret;
+
+	cmd = CMD_WRITE_EVCR;
+	ret = spi_flash_write_common(flash, &cmd, 1, &evcr, 1);
+	if (ret < 0) {
+		debug("SF: error while writing EVCR register\n");
+		return ret;
+	}
+
+	return 0;
+}
+#endif
+
 #ifdef CONFIG_SPI_FLASH_BAR
 static int spi_flash_write_bar(struct spi_flash *flash, u32 offset)
 {
@@ -843,6 +874,34 @@ static int spansion_quad_enable(struct spi_flash *flash)
 }
 #endif
 
+#ifdef CONFIG_SPI_FLASH_STMICRO
+static int micron_quad_enable(struct spi_flash *flash)
+{
+	u8 qeb_status;
+	int ret;
+
+	ret = read_evcr(flash, &qeb_status);
+	if (ret < 0)
+		return ret;
+
+	if (!(qeb_status & STATUS_QEB_MICRON))
+		return 0;
+
+	ret = write_evcr(flash, qeb_status & ~STATUS_QEB_MICRON);
+	if (ret < 0)
+		return ret;
+
+	/* read EVCR and check it */
+	ret = read_evcr(flash, &qeb_status);
+	if (!(ret >= 0 && !(qeb_status & STATUS_QEB_MICRON))) {
+		printf("SF: Micron EVCR Quad bit not clear\n");
+		return -EINVAL;
+	}
+
+	return ret;
+}
+#endif
+
 static int set_quad_mode(struct spi_flash *flash, u8 idcode0)
 {
 	switch (idcode0) {
@@ -857,8 +916,7 @@ static int set_quad_mode(struct spi_flash *flash, u8 idcode0)
 #endif
 #ifdef CONFIG_SPI_FLASH_STMICRO
 	case SPI_FLASH_CFI_MFR_STMICRO:
-		debug("SF: QEB is volatile for %02x flash\n", idcode0);
-		return 0;
+		return micron_quad_enable(flash);
 #endif
 	default:
 		printf("SF: Need set QEB func for %02x flash\n", idcode0);