Adding bcm2835-sdhost driver, and an overlay to enable it

BCM2835 has two SD card interfaces. This driver uses the other one.

Author: Phil Elwell

arch/arm/boot/dts/Makefile

@@ -34,6 +34,7 @@ dtb-$(RPI_DT_OVERLAYS) += piscreen-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += pitft28-resistive-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += pps-gpio-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += rpi-display-overlay.dtb
+dtb-$(RPI_DT_OVERLAYS) += sdhost-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += w1-gpio-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += w1-gpio-pullup-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += spi-bcm2835-overlay.dtb

arch/arm/boot/dts/sdhost-overlay.dts

@@ -0,0 +1,59 @@
+/dts-v1/;
+/plugin/;
+
+/{
+	compatible = "brcm,bcm2708";
+
+	fragment@0 {
+		target = <&soc>;
+		__overlay__ {
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			sdhost: sdhost@7e202000 {
+				compatible = "brcm,bcm2835-sdhost";
+				reg = <0x7e202000 0x100>;
+				interrupts = <2 24>;
+				clocks = <&clk_sdhost>;
+				dmas = <&dma 13>,
+				       <&dma 13>;
+				dma-names = "tx", "rx";
+				pinctrl-names = "default";
+				pinctrl-0 = <&sdhost_pins>;
+				status = "okay";
+			};
+
+			clocks {
+				#address-cells = <1>;
+				#size-cells = <0>;
+
+				clk_sdhost: clock@3 {
+					compatible = "fixed-clock";
+					reg = <0>;
+					#clock-cells = <0>;
+					clock-output-names = "sdhost";
+					clock-frequency = <250000000>;
+				};
+			};
+		};
+	};
+
+	fragment@1 {
+		target = <&gpio>;
+		__overlay__ {
+			sdhost_pins: sdhost_pins {
+				brcm,pins = <48 49 50 51 52 53>;
+				brcm,function = <4>; /* alt0 */
+			};
+		};
+	};
+
+	fragment@2 {
+		target = <&mmc>;
+		__overlay__ {
+			/* Find a way to disable the other driver */
+			compatible = "";
+			status = "disabled";
+		};
+	};
+};

arch/arm/configs/bcm2709_defconfig

@@ -956,6 +956,7 @@ CONFIG_MMC=y
 CONFIG_MMC_BLOCK_MINORS=32
 CONFIG_MMC_BCM2835=y
 CONFIG_MMC_BCM2835_DMA=y
+CONFIG_MMC_BCM2835_SDHOST=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_PLTFM=y
 CONFIG_MMC_SPI=m

arch/arm/configs/bcmrpi_defconfig

@@ -949,6 +949,7 @@ CONFIG_MMC=y
 CONFIG_MMC_BLOCK_MINORS=32
 CONFIG_MMC_BCM2835=y
 CONFIG_MMC_BCM2835_DMA=y
+CONFIG_MMC_BCM2835_SDHOST=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_PLTFM=y
 CONFIG_MMC_SPI=m

drivers/mmc/host/Kconfig

@@ -33,6 +33,16 @@ config MMC_BCM2835_PIO_DMA_BARRIER
 
 	  If unsure, say 2 here.
 
+config MMC_BCM2835_SDHOST
+	tristate "Support for the SDHost controller on BCM2708/9"
+	depends on (MACH_BCM2708 || MACH_BCM2709)
+	help
+	  This selects the SDHost controller on BCM2835/6.
+
+	  If you have a controller with this interface, say Y or M here.
+
+	  If unsure, say N.
+
 config MMC_ARMMMCI
 	tristate "ARM AMBA Multimedia Card Interface support"
 	depends on ARM_AMBA

drivers/mmc/host/Makefile

@@ -18,6 +18,7 @@ obj-$(CONFIG_MMC_SDHCI_S3C)	+= sdhci-s3c.o
 obj-$(CONFIG_MMC_SDHCI_SIRF)   	+= sdhci-sirf.o
 obj-$(CONFIG_MMC_SDHCI_F_SDH30)	+= sdhci_f_sdh30.o
 obj-$(CONFIG_MMC_SDHCI_SPEAR)	+= sdhci-spear.o
+obj-$(CONFIG_MMC_BCM2835_SDHOST)	+= bcm2835-sdhost.o
 obj-$(CONFIG_MMC_BCM2835)	+= bcm2835-mmc.o
 obj-$(CONFIG_MMC_WBSD)		+= wbsd.o
 obj-$(CONFIG_MMC_AU1X)		+= au1xmmc.o