mmc: add a driver for the Renesas usdhi6rol0 SD/SDIO host controller

This patch adds a driver for the Renesas usdhi6rol0 SD/SDIO host controller
in both PIO and DMA modes.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com>
Signed-off-by: Chris Ball <chris@printf.net>

Documentation/devicetree/bindings/mmc/usdhi6rol0.txt

+* Renesas usdhi6rol0 SD/SDIO host controller
+
+Required properties:
+
+- compatible:	must be
+		"renesas,usdhi6rol0"
+- interrupts:	3 interrupts, named "card detect", "data" and "SDIO" must be
+		specified
+- clocks:	a clock binding for the IMCLK input
+
+Optional properties:
+
+- vmmc-supply:	a phandle of a regulator, supplying Vcc to the card
+- vqmmc-supply:	a phandle of a regulator, supplying VccQ to the card
+
+Additionally any standard mmc bindings from mmc.txt can be used.
+
+Example:
+
+sd0: sd@ab000000 {
+	compatible = "renesas,usdhi6rol0";
+	reg = <0xab000000 0x200>;
+	interrupts = <0 23 0x4
+		      0 24 0x4
+		      0 25 0x4>;
+	interrupt-names = "card detect", "data", "SDIO";
+	bus-width = <4>;
+	max-frequency = <50000000>;
+	cap-power-off-card;
+	clocks = <&imclk>;
+	vmmc-supply = <&vcc_sd0>;
+	vqmmc-supply = <&vccq_sd0>;
+};

drivers/mmc/host/Kconfig

@@ -697,6 +697,12 @@ config MMC_WMT
 	  To compile this driver as a module, choose M here: the
 	  module will be called wmt-sdmmc.
 
+config MMC_USDHI6ROL0
+	tristate "Renesas USDHI6ROL0 SD/SDIO Host Controller support"
+	help
+	  This selects support for the Renesas USDHI6ROL0 SD/SDIO
+	  Host Controller
+
 config MMC_REALTEK_PCI
 	tristate "Realtek PCI-E SD/MMC Card Interface Driver"
 	depends on MFD_RTSX_PCI

drivers/mmc/host/Makefile

@@ -52,6 +52,7 @@ obj-$(CONFIG_MMC_USHC)		+= ushc.o
 obj-$(CONFIG_MMC_WMT)		+= wmt-sdmmc.o
 obj-$(CONFIG_MMC_MOXART)	+= moxart-mmc.o
 obj-$(CONFIG_MMC_SUNXI)		+= sunxi-mmc.o
+obj-$(CONFIG_MMC_USDHI6ROL0)	+= usdhi6rol0.o
 
 obj-$(CONFIG_MMC_REALTEK_PCI)	+= rtsx_pci_sdmmc.o
 obj-$(CONFIG_MMC_REALTEK_USB)	+= rtsx_usb_sdmmc.o