arc: vdk: Add support of MMC controller

ARC VDK virtual platform emulates host MMC controller (DW Mobile Storage)
and moreover rootfs is situated on that virtual card.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/boot/dts/vdk_axs10x_mb.dtsi

@@ -23,6 +23,12 @@ apbclk: apbclk {
 				#clock-cells = <0>;
 			};
 
+			mmcclk: mmcclk {
+				compatible = "fixed-clock";
+				clock-frequency = <50000000>;
+				#clock-cells = <0>;
+			};
+
 			pguclk: pguclk {
 				#clock-cells = <0>;
 				compatible = "fixed-clock";
@@ -94,5 +100,17 @@ ps2: ps2@e0017400 {
 			interrupts = <5>;
 			interrupt-names = "arc_ps2_irq";
 		};
+
+		mmc@0x15000 {
+			compatible = "snps,dw-mshc";
+			reg = <0x15000 0x400>;
+			num-slots = <1>;
+			fifo-depth = <1024>;
+			card-detect-delay = <200>;
+			clocks = <&apbclk>, <&mmcclk>;
+			clock-names = "biu", "ciu";
+			interrupts = <7>;
+			bus-width = <4>;
+		};
 	};
 };

arch/arc/configs/vdk_hs38_smp_defconfig

@@ -78,6 +78,10 @@ CONFIG_USB_OHCI_HCD=y
 CONFIG_USB_OHCI_HCD_PLATFORM=y
 CONFIG_USB_STORAGE=y
 CONFIG_USB_SERIAL=y
+CONFIG_MMC=y
+CONFIG_MMC_SDHCI=y
+CONFIG_MMC_SDHCI_PLTFM=y
+CONFIG_MMC_DW=y
 # CONFIG_IOMMU_SUPPORT is not set
 CONFIG_EXT3_FS=y
 CONFIG_MSDOS_FS=y