arm: exynos: Read default MMC device from XOM[7:5] pins

XOM pins provide information for iROM bootloader about the boot device.
Those pins are mapped to lower bits of OP_MODE register (0x10000008),
which is common for all Exynos SoC variants. Set the default MMC device id
to reflect the boot device selected by XOM[7:5] pins (2 for the SD or 0 for
the eMMC).

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
diff --git a/board/samsung/common/board.c b/board/samsung/common/board.c
index 5d4646d..390060e 100644
--- a/board/samsung/common/board.c
+++ b/board/samsung/common/board.c
@@ -25,6 +25,8 @@
 #include <asm/arch/sromc.h>
 #include <lcd.h>
 #include <i2c.h>
+#include <mmc.h>
+#include <stdio_dev.h>
 #include <usb.h>
 #include <dwc3-uboot.h>
 #include <samsung/misc.h>
@@ -43,6 +45,20 @@
 	return 0;
 }
 
+/**
+ * get_boot_mmc_dev() - read boot MMC device id from XOM[7:5] pins.
+ */
+static int get_boot_mmc_dev(void)
+{
+	u32 mode = readl(EXYNOS4_OP_MODE) & 0x1C;
+
+	if (mode == 0x04)
+		return 2; /* MMC2: SD */
+
+	/* MMC0: eMMC or unknown */
+	return 0;
+}
+
 #if defined CONFIG_EXYNOS_TMU
 /* Boot Time Thermal Analysis for SoC temperature threshold breach */
 static void boot_temp_check(void)
@@ -281,6 +297,8 @@
 {
 	struct udevice *dev;
 	int ret;
+	int mmcbootdev = get_boot_mmc_dev();
+	char mmcbootdev_str[16];
 
 	stdio_print_current_devices();
 	ret = uclass_first_device_err(UCLASS_CROS_EC, &dev);
@@ -293,6 +311,11 @@
 		panic("Cannot init cros-ec device");
 		return -1;
 	}
+
+	printf("Boot device: MMC(%u)\n", mmcbootdev);
+	sprintf(mmcbootdev_str, "%u", mmcbootdev);
+	env_set("mmcbootdev", mmcbootdev_str);
+
 	return 0;
 }
 #endif
@@ -360,3 +383,8 @@
 #endif
 	return 0;
 }
+
+int mmc_get_env_dev(void)
+{
+	return get_boot_mmc_dev();
+}