sf: Add flag status register polling support

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@xilinx.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/mtd/spi/spi_flash.c

@@ -200,12 +200,19 @@ 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;
+	u8 cmd = flash->poll_cmd;
+
+	if (cmd == CMD_FLAG_STATUS) {
+		poll_bit = STATUS_PEC;
+		check_status = poll_bit;
+	}
 
 	ret = spi_xfer(spi, 8, &cmd, NULL, SPI_XFER_BEGIN);
 	if (ret) {
-		debug("SF: Failed to send command %02x: %d\n", cmd, ret);
+		debug("SF: fail to read %s status register\n",
+			cmd == CMD_READ_STATUS ? "read" : "flag");
 		return ret;
 	}
 
@@ -217,14 +224,14 @@ int spi_flash_cmd_wait_ready(struct spi_flash *flash, unsigned long timeout)
 		if (ret)
 			return -1;
 
-		if ((status & poll_bit) == 0)
+		if ((status & poll_bit) == check_status)
 			break;
 
 	} while (get_timer(timebase) < timeout);
 
 	spi_xfer(spi, 0, NULL, NULL, SPI_XFER_END);
 
-	if ((status & poll_bit) == 0)
+	if ((status & poll_bit) == check_status)
 		return 0;
 
 	/* Timed out */
@@ -584,6 +591,7 @@ void *spi_flash_do_alloc(int offset, int size, struct spi_slave *spi,
 	/* Set up some basic fields - caller will sort out sizes */
 	flash->spi = spi;
 	flash->name = name;
+	flash->poll_cmd = CMD_READ_STATUS;
 
 	flash->read = spi_flash_cmd_read_fast;
 	flash->write = spi_flash_cmd_write_multi;

drivers/mtd/spi/spi_flash_internal.h

@@ -22,6 +22,7 @@
 #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
@@ -45,6 +46,7 @@
 
 /* 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);

drivers/mtd/spi/stmicro.c

@@ -210,5 +210,9 @@ struct spi_flash *spi_flash_probe_stmicro(struct spi_slave *spi, u8 * idcode)
 	flash->sector_size = 256 * params->pages_per_sector;
 	flash->size = flash->sector_size * params->nr_sectors;
 
+	/* for >= 512MiB flashes, use flag status instead of read_status */
+	if (flash->size >= 0x4000000)
+		flash->poll_cmd = CMD_FLAG_STATUS;
+
 	return flash;
 }

include/spi_flash.h

@@ -46,6 +46,9 @@ struct spi_flash {
 	/* Current flash bank */
 	u8		bank_curr;
 #endif
+	/* Poll cmd - for flash erase/program */
+	u8		poll_cmd;
+
 	void *memory_map;	/* Address of read-only SPI flash access */
 	int		(*read)(struct spi_flash *flash, u32 offset,
 				size_t len, void *buf);