cmd_mmc: add support for device command for selecting mmc device

This patch improves device command for selecting mmc device

Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

common/cmd_mmc.c

@@ -26,19 +26,70 @@
 #include <mmc.h>
 
 #ifndef CONFIG_GENERIC_MMC
+int curr_device = -1;
+
 int do_mmc (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 {
-	if (mmc_legacy_init (1) != 0) {
-		printf ("No MMC card found\n");
+	int dev;
+
+	if (argc < 2) {
+		cmd_usage(cmdtp);
 		return 1;
 	}
+
+	if (strcmp(argv[1], "init") == 0) {
+		if (argc == 2) {
+			if (curr_device < 0)
+				dev = 1;
+			else
+				dev = curr_device;
+		} else if (argc == 3) {
+			dev = (int)simple_strtoul(argv[2], NULL, 10);
+		} else {
+			cmd_usage(cmdtp);
+			return 1;
+		}
+
+		if (mmc_legacy_init(dev) != 0) {
+			puts("No MMC card found\n");
+			return 1;
+		}
+
+		curr_device = dev;
+		printf("mmc%d is available\n", curr_device);
+	} else if (strcmp(argv[1], "device") == 0) {
+		if (argc == 2) {
+			if (curr_device < 0) {
+				puts("No MMC device available\n");
+				return 1;
+			}
+		} else if (argc == 3) {
+			dev = (int)simple_strtoul(argv[2], NULL, 10);
+
+#ifdef CONFIG_SYS_MMC_SET_DEV
+			if (mmc_set_dev(dev) != 0)
+				return 1;
+#endif
+			curr_device = dev;
+		} else {
+			cmd_usage(cmdtp);
+			return 1;
+		}
+
+		printf("mmc%d is current device\n", curr_device);
+	} else {
+		cmd_usage(cmdtp);
+		return 1;
+	}
+
 	return 0;
 }
 
 U_BOOT_CMD(
-	mmcinit,	1,	0,	do_mmc,
-	"init mmc card",
-	NULL
+	mmc, 3, 1, do_mmc,
+	"MMC sub-system",
+	"init [dev] - init MMC sub system\n"
+	"mmc device [dev] - show or set current device\n"
 );
 #else /* !CONFIG_GENERIC_MMC */