ARM: uniphier: add a command to find the first MMC (non-SD) device

UniPhier SoC family supports both (e)MMC boot and SD card boot;
however, both of them are handled in the same uclass.

When booting from the eMMC, we want to know the device number
of the (e)MMC, not SD.  This command is useful to find the first
MMC (non-SD) device.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/arm/mach-uniphier/boot-mode/boot-mode.c

@@ -7,6 +7,7 @@
 #include <common.h>
 #include <mmc.h>
 #include <spl.h>
+#include <linux/err.h>
 
 #include "../sbc/sbc-regs.h"
 #include "../soc-info.h"
@@ -77,3 +78,36 @@ u32 spl_boot_mode(void)
 
 	return MMCSD_MODE_EMMCBOOT;
 }
+
+#if defined(CONFIG_DM_MMC) && !defined(CONFIG_SPL_BUILD)
+static int find_first_mmc_device(void)
+{
+	struct mmc *mmc;
+	int i;
+
+	for (i = 0; (mmc = find_mmc_device(i)); i++) {
+		if (!mmc_init(mmc) && IS_MMC(mmc))
+			return i;
+	}
+
+	return -ENODEV;
+}
+
+static int do_mmcsetn(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	int dev;
+
+	dev = find_first_mmc_device();
+	if (dev < 0)
+		return CMD_RET_FAILURE;
+
+	setenv_ulong("mmc_first_dev", dev);
+	return CMD_RET_SUCCESS;
+}
+
+U_BOOT_CMD(
+	   mmcsetn,	1,	1,	do_mmcsetn,
+	"Set the first MMC (not SD) dev number to \"mmc_first_dev\" enviroment",
+	""
+);
+#endif