Add method for enabling bkops via one-time fuse.

This patch added the method to enable the bkops.
In ext_csd register, BKOPS_EN bit is one-time programable.
So if you want to use the bkops, use the this command.

$ mmc bkops enable /dev/mmcblk0

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewd-by: Venkatraman S <svenkatr@ti.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/mmc_cmds.c b/mmc_cmds.c
index 90619db..05d7e13 100644
--- a/mmc_cmds.c
+++ b/mmc_cmds.c
@@ -280,6 +280,44 @@
 	return ret;
 }
 
+int do_write_bkops_en(int nargs, char **argv)
+{
+	__u8 ext_csd[512], value = 0;
+	int fd, ret;
+	char *device;
+
+	CHECK(nargs != 2, "Usage: mmc bkops enable </path/to/mmcblkX>\n",
+			exit(1));
+
+	device = argv[1];
+
+	fd = open(device, O_RDWR);
+	if (fd < 0) {
+		perror("open");
+		exit(1);
+	}
+
+	ret = read_extcsd(fd, ext_csd);
+	if (ret) {
+		fprintf(stderr, "Could not read EXT_CSD from %s\n", device);
+		exit(1);
+	}
+
+	if (!(ext_csd[EXT_CSD_BKOPS_SUPPORT] & 0x1)) {
+		fprintf(stderr, "%s doesn't support BKOPS\n", device);
+		exit(1);
+	}
+
+	ret = write_extcsd_value(fd, EXT_CSD_BKOPS_EN, BKOPS_ENABLE);
+	if (ret) {
+		fprintf(stderr, "Could not write 0x%02x to EXT_CSD[%d] in %s\n",
+			value, EXT_CSD_BKOPS_EN, device);
+		exit(1);
+	}
+
+	return ret;
+}
+
 int do_read_extcsd(int nargs, char **argv)
 {
 	__u8 ext_csd[512], ext_csd_rev, reg;