BCM270X_DT: Add SDIO overlay

Enable SDIO from MMC interface via GPIOs 22-27. Includes the sdhost
overlay to free up the MMC interface.

arch/arm/boot/dts/overlays/Makefile

@@ -43,6 +43,7 @@ dtb-$(RPI_DT_OVERLAYS) += rpi-ft5406-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += rpi-proto-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += rpi-sense-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += sdhost-overlay.dtb
+dtb-$(RPI_DT_OVERLAYS) += sdio-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += spi-bcm2708-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += spi-bcm2835-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += spi-gpio35-39-overlay.dtb

arch/arm/boot/dts/overlays/README

@@ -507,6 +507,21 @@ Params: overclock_50 Clock (in MHz) to use when the MMC framework
  debug Enable debug output (default off)
 
 
+Name: sdio
+Info: Selects the bcm2835-sdhost SD/MMC driver, optionally with overclock,
+ and enables SDIO via GPIOs 22-27.
+Load: dtoverlay=sdio,<param>=<val>
+Params: overclock_50 Clock (in MHz) to use when the MMC framework
+ requests 50MHz
+
+ force_pio Disable DMA support (default off)
+
+ pio_limit Number of blocks above which to use DMA
+ (default 1)
+
+ debug Enable debug output (default off)
+
+
 Name: spi-bcm2708
 Info: Selects the bcm2708-spi SPI driver
 Load: dtoverlay=spi-bcm2708

arch/arm/boot/dts/overlays/sdio-overlay.dts

@@ -0,0 +1,29 @@
+/* Enable SDIO from MMC interface via GPIOs 22-27. Includes sdhost overlay. */
+
+/include/ "sdhost-overlay.dts"
+
+/{
+ compatible = "brcm,bcm2708";
+
+ fragment@3 {
+ target = <&mmc>;
+ __overlay__ {
+ compatible = "brcm,bcm2835-mmc";
+ pinctrl-names = "default";
+ pinctrl-0 = <&sdio_pins>;
+ non-removable;
+ status = "okay";
+ };
+ };
+
+ fragment@4 {
+ target = <&gpio>;
+ __overlay__ {
+ sdio_pins: sdio_pins {
+ brcm,pins = <22 23 24 25 26 27>;
+ brcm,function = <7 7 7 7 7 7>; /* ALT3 = SD1 */
+ brcm,pull = <0 2 2 2 2 2>;
+ };
+ };
+ };
+};