Add support for disabling 512B emulation

In this patch, we add a utility to disable emulation mode in eMMC-4.5.
This is done to increase the data sector size to 4KB.
Signed-off-by: Saugata Das <saugata.das@linaro.org>
Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org>
Reviewed-by: Namjae Jeon <linkinjeon@gmail.com>
Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

mmc.c

@@ -65,6 +65,11 @@ static struct Command commands[] = {
 		"Set the eMMC writeprotect status of <device>.",
 	  NULL
 	},
+	{ do_disable_512B_emulation, -1,
+	  "disable 512B emulation", "<device>\n"
+		"Set the eMMC data sector size to 4KB by disabling emulation on <device>.",
+	  NULL
+	},
 	{ do_write_boot_en, -3,
 	  "bootpart enable", "<boot_partition> " "<send_ack> " "<device>\n"
 		"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.",

mmc.h

@@ -34,8 +34,18 @@
 #define EXT_CSD_BOOT_INFO		228	/* R/W */
 #define EXT_CSD_PART_SWITCH_TIME	199
 #define EXT_CSD_BOOT_CFG		179
-#define EXT_CSD_BOOT_WP			173
 #define EXT_CSD_PART_CONFIG		179
+#define EXT_CSD_BOOT_WP			173
+#define EXT_CSD_WR_REL_PARAM		166
+#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 */
+
+/*
+ * WR_REL_PARAM field definitions
+ */
+#define HS_CTRL_REL	(1<<0)
+#define EN_REL_WR	(1<<2)
 
 /*
  * EXT_CSD field definitions

mmc_cmds.c

@@ -170,6 +170,50 @@ int do_writeprotect_set(int nargs, char **argv)
 	return ret;
 }
 
+int do_disable_512B_emulation(int nargs, char **argv)
+{
+	__u8 ext_csd[512], native_sector_size, data_sector_size, wr_rel_param;
+	int fd, ret;
+	char *device;
+
+	CHECK(nargs != 2, "Usage: mmc disable 512B emulation </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);
+	}
+
+	wr_rel_param = ext_csd[EXT_CSD_WR_REL_PARAM];
+	native_sector_size = ext_csd[EXT_CSD_NATIVE_SECTOR_SIZE];
+	data_sector_size = ext_csd[EXT_CSD_DATA_SECTOR_SIZE];
+
+	if (native_sector_size && !data_sector_size &&
+	   (wr_rel_param & EN_REL_WR)) {
+		ret = write_extcsd_value(fd, EXT_CSD_USE_NATIVE_SECTOR, 1);
+
+		if (ret) {
+			fprintf(stderr, "Could not write 0x%02x to EXT_CSD[%d] in %s\n",
+					1, EXT_CSD_BOOT_WP, device);
+			exit(1);
+		}
+		printf("MMC disable 512B emulation successful.  Now reset the device to switch to 4KB native sector mode.\n");
+	} else if (native_sector_size && data_sector_size) {
+		printf("MMC 512B emulation mode is already disabled; doing nothing.\n");
+	} else {
+		printf("MMC does not support disabling 512B emulation mode.\n");
+	}
+
+	return ret;
+}
+
 int do_write_boot_en(int nargs, char **argv)
 {
 	__u8 ext_csd[512];
@@ -236,7 +280,6 @@ int do_write_boot_en(int nargs, char **argv)
 	return ret;
 }
 
-
 int do_read_extcsd(int nargs, char **argv)
 {
 	__u8 ext_csd[512], ext_csd_rev, reg;

mmc_cmds.h

@@ -19,4 +19,5 @@ int do_read_extcsd(int nargs, char **argv);
 int do_write_extcsd(int nargs, char **argv);
 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);