[U-Boot] [PATCH v2 16/16] sf: Add Flag status register polling support

[Jagannadha Sutradharudu Teki]

Flag status register polling is required for micron 512Mb flash
devices onwards, for performing erase/program operations.

Like polling for WIP(Write-In-Progress) bit in read status register,
spi_flash_cmd_wait_ready will poll for PEC(Program-Erase-Control)
bit in flag status register.

Signed-off-by: Jagannadha Sutradharudu Teki <jaganna at xilinx.com>
---
Changes for v2:
        - none

 drivers/mtd/spi/spi_flash.c          | 15 ++++++++++++---
 drivers/mtd/spi/spi_flash_internal.h |  3 +++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
index 527423d..8cd2988 100644
--- a/drivers/mtd/spi/spi_flash.c
+++ b/drivers/mtd/spi/spi_flash.c
@@ -195,25 +195,34 @@ int spi_flash_cmd_wait_ready(struct spi_flash *flash, unsigned long timeout)
 	unsigned long timebase;
 	int ret;
 	u8 status;
+	u8 check_status = 0x0;
 	u8 poll_bit = STATUS_WIP;
 	u8 cmd = CMD_READ_STATUS;
 
+	if ((flash->idcode0 == 0x20) &&
+			(flash->size >= SPI_FLASH_512MB_STMIC)) {
+		poll_bit = STATUS_PEC;
+		check_status = poll_bit;
+		cmd = CMD_FLAG_STATUS;
+	}
+
 	timebase = get_timer(0);
 	do {
 		WATCHDOG_RESET();
 
 		ret = spi_flash_read_common(flash, &cmd, 1, &status, 1);
 		if (ret < 0) {
-			debug("SF: fail to read read status register\n");
+			debug("SF: fail to read %s status register\n",
+				cmd == CMD_READ_STATUS ? "read" : "flag");
 			return ret;
 		}
 
-		if ((status & poll_bit) == 0)
+		if ((status & poll_bit) == check_status)
 			break;
 
 	} while (get_timer(timebase) < timeout);
 
-	if ((status & poll_bit) == 0)
+	if ((status & poll_bit) == check_status)
 		return 0;
 
 	/* Timed out */
diff --git a/drivers/mtd/spi/spi_flash_internal.h b/drivers/mtd/spi/spi_flash_internal.h
index ac4530f..cb7a505 100644
--- a/drivers/mtd/spi/spi_flash_internal.h
+++ b/drivers/mtd/spi/spi_flash_internal.h
@@ -13,6 +13,7 @@
 #define SPI_FLASH_SECTOR_ERASE_TIMEOUT	(10 * CONFIG_SYS_HZ)
 
 #define SPI_FLASH_16MB_BOUN		0x1000000
+#define SPI_FLASH_512MB_STMIC		0x4000000
 
 /* Common commands */
 #define CMD_READ_ID			0x9f
@@ -24,6 +25,7 @@
 #define CMD_PAGE_PROGRAM		0x02
 #define CMD_WRITE_DISABLE		0x04
 #define CMD_READ_STATUS			0x05
+#define CMD_FLAG_STATUS			0x70
 #define CMD_WRITE_ENABLE		0x06
 #define CMD_ERASE_4K			0x20
 #define CMD_ERASE_32K			0x52
@@ -38,6 +40,7 @@
 
 /* Common status */
 #define STATUS_WIP			0x01
+#define STATUS_PEC			0x80
 
 /* Send a single-byte command to the device and read the response */
 int spi_flash_cmd(struct spi_slave *spi, u8 cmd, void *response, size_t len);
-- 
1.8.3