[U-Boot] [U-Boot,v2 5/6] sf: Add config register reading support

[Jagannadha Sutradharudu Teki]

This patch provides support to read a flash config register.

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

User need to get the data through spi_flash_cmd_read_config()
based on their usage.

Signed-off-by: Jagannadha Sutradharudu Teki <jagannadh.teki at gmail.com>
---
Changes in v2: none
    
 drivers/mtd/spi/spi_flash.c          |   15 +++++++++++++++
 drivers/mtd/spi/spi_flash_internal.h |    4 ++++
 2 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
index cad6c40..5bddde4 100644
--- a/drivers/mtd/spi/spi_flash.c
+++ b/drivers/mtd/spi/spi_flash.c
@@ -314,6 +314,21 @@ int spi_flash_cmd_write_config(struct spi_flash *flash, u8 cr)
 	return 0;
 }
 
+int spi_flash_cmd_read_config(struct spi_flash *flash, void *data)
+{
+	u8 cmd;
+	int ret;
+
+	cmd = CMD_READ_CONFIG;
+	ret = spi_flash_read_common(flash, &cmd, sizeof(cmd), (void *)data, 1);
+	if (ret < 0) {
+		debug("SF: fail to read config register\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 825b398..844e82e 100644
--- a/drivers/mtd/spi/spi_flash_internal.h
+++ b/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_READ_CONFIG			0x35
 #define CMD_WRITE_ENABLE		0x06
 #define CMD_ERASE_4K			0x20
 #define CMD_ERASE_32K			0x52
@@ -83,6 +84,9 @@ 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);
 
+/* Read the config register */
+int spi_flash_cmd_read_config(struct spi_flash *flash, void *data);
+
 /*
  * 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