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>

mmc.c

@@ -75,6 +75,11 @@ static struct Command commands[] = {
 		"Enable the boot partition for the <device>.\nTo receive acknowledgment of boot from the card set <send_ack>\nto 1, else set it to 0.",
 	  NULL
 	},
+	{ do_write_bkops_en, -1,
+	  "bkops enable", "<device>\n"
+		"Enable the eMMC BKOPS feature on <device>.\nNOTE!  This is a one-time programmable (unreversible) change.",
+	  NULL
+	},
 	{ 0, 0, 0, 0 }
 };
 

mmc.h

@@ -31,12 +31,14 @@
  */
 #define EXT_CSD_S_CMD_SET		504
 #define EXT_CSD_HPI_FEATURE		503
+#define EXT_CSD_BKOPS_SUPPORT		502	/* RO */
 #define EXT_CSD_BOOT_INFO		228	/* R/W */
 #define EXT_CSD_PART_SWITCH_TIME	199
 #define EXT_CSD_BOOT_CFG		179
 #define EXT_CSD_PART_CONFIG		179
 #define EXT_CSD_BOOT_WP			173
 #define EXT_CSD_WR_REL_PARAM		166
+#define EXT_CSD_BKOPS_EN		163	/* R/W */
 #define EXT_CSD_NATIVE_SECTOR_SIZE	63 /* R */
 #define EXT_CSD_USE_NATIVE_SECTOR	62 /* R/W */
 #define EXT_CSD_DATA_SECTOR_SIZE	61 /* R */
@@ -47,6 +49,11 @@
 #define HS_CTRL_REL	(1<<0)
 #define EN_REL_WR	(1<<2)
 
+/*
+ * BKOPS_EN field definition
+ */
+#define BKOPS_ENABLE	(1<<0)
+
 /*
  * EXT_CSD field definitions
  */

mmc_cmds.c

@@ -280,6 +280,44 @@ int do_write_boot_en(int nargs, char **argv)
 	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;

mmc_cmds.h

@@ -21,3 +21,4 @@ int do_writeprotect_get(int nargs, char **argv);
 int do_writeprotect_set(int nargs, char **argv);
 int do_disable_512B_emulation(int nargs, char **argv);
 int do_write_boot_en(int nargs, char **argv);
+int do_write_bkops_en(int nargs, char **argv);