[U-Boot] [U-Boot, v2 4/6] sf: Add configuration register writing support

[Jagannadha Sutradharudu Teki]

This patch provides support to program a flash config register.

Configuration register contains the control bits used to configure
the different configurations and security features of a device.

User need to set these bits through spi_flash_cmd_write_config()
based on their usage.

Signed-off-by: Jagannadha Sutradharudu Teki <jagannadh.teki at gmail.com>
---
Changes in v2:
        Improved code logic 

 drivers/mtd/spi/spi_flash.c          |   35 ++++++++++++++++++++++++++++++++++
 drivers/mtd/spi/spi_flash_internal.h |    3 ++
 2 files changed, 38 insertions(+), 0 deletions(-)

diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
index bf5ec4a..cad6c40 100644
--- a/drivers/mtd/spi/spi_flash.c
+++ b/drivers/mtd/spi/spi_flash.c
@@ -279,6 +279,41 @@ int spi_flash_cmd_read_status(struct spi_flash *flash, void *data)
 	return 0;
 }
 
+int spi_flash_cmd_write_config(struct spi_flash *flash, u8 cr)
+{
+	u8 data[2];
+	u8 cmd;
+	int ret;
+
+	ret = spi_flash_cmd_read_status(flash, (void *)&data[0]);
+	if (ret < 0) {
+		debug("SF: fail to read status register\n");
+		return ret;
+	}
+
+	ret = spi_flash_cmd_write_enable(flash);
+	if (ret < 0) {
+		debug("SF: enabling write failed\n");
+		return ret;
+	}
+
+	cmd = CMD_WRITE_STATUS;
+	data[1] = cr;
+	ret = spi_flash_cmd_write(flash->spi, &cmd, 1, &data, 2);
+	if (ret) {
+		debug("SF: fail to write config register\n");
+		return ret;
+	}
+
+	ret = spi_flash_cmd_wait_ready(flash, SPI_FLASH_PROG_TIMEOUT);
+	if (ret < 0) {
+		debug("SF: write config register timed out\n");
+		return ret;
+	}
+
+	return 0;
+}
+
 /*
  * The following table holds all device probe functions
  *
diff --git a/drivers/mtd/spi/spi_flash_internal.h b/drivers/mtd/spi/spi_flash_internal.h
index 8232595..825b398 100644
--- a/drivers/mtd/spi/spi_flash_internal.h
+++ b/drivers/mtd/spi/spi_flash_internal.h
@@ -80,6 +80,9 @@ int spi_flash_cmd_write_status(struct spi_flash *flash, u8 sr);
 /* Read the status register */
 int spi_flash_cmd_read_status(struct spi_flash *flash, void *data);
 
+/* Program the config register. */
+int spi_flash_cmd_write_config(struct spi_flash *flash, u8 cr);
+
 /*
  * Same as spi_flash_cmd_read() except it also claims/releases the SPI
  * bus. Used as common part of the ->read() operation.
-- 
1.7.0.4