spi: bcm270x: dt: move to cs-gpio and add an overlay for GPIO 35-39

Moves SPI settings for chip-selects to framework managed GPIOs.
And also adds an overlay to move GPIOs used for SPI to GPIO35-39

Author: msperl

arch/arm/boot/dts/bcm2708-rpi-b-plus.dts

@@ -9,10 +9,15 @@
 
 &gpio {
 	spi0_pins: spi0_pins {
-		brcm,pins = <7 8 9 10 11>;
+		brcm,pins = <9 10 11>;
 		brcm,function = <4>; /* alt0 */
 	};
 
+	spi0_cs_pins: spi0_cs_pins {
+		brcm,pins = <8 7>;
+		brcm,function = <1>; /* output */
+	};
+
 	i2c0_pins: i2c0 {
 		brcm,pins = <0 1>;
 		brcm,function = <4>;
@@ -44,7 +49,8 @@
 
 &spi0 {
 	pinctrl-names = "default";
-	pinctrl-0 = <&spi0_pins>;
+	pinctrl-0 = <&spi0_pins &spi0_cs_pins>;
+	cs-gpios = <&gpio 8 1>, <&gpio 7 1>;
 
 	spidev@0{
 		compatible = "spidev";

arch/arm/boot/dts/bcm2708-rpi-b.dts

@@ -9,10 +9,15 @@
 
 &gpio {
 	spi0_pins: spi0_pins {
-		brcm,pins = <7 8 9 10 11>;
+		brcm,pins = <9 10 11>;
 		brcm,function = <4>; /* alt0 */
 	};
 
+	spi0_cs_pins: spi0_cs_pins {
+		brcm,pins = <8 7>;
+		brcm,function = <1>; /* output */
+	};
+
 	i2c0_pins: i2c0 {
 		brcm,pins = <0 1>;
 		brcm,function = <4>;
@@ -44,7 +49,8 @@
 
 &spi0 {
 	pinctrl-names = "default";
-	pinctrl-0 = <&spi0_pins>;
+	pinctrl-0 = <&spi0_pins &spi0_cs_pins>;
+	cs-gpios = <&gpio 8 1>, <&gpio 7 1>;
 
 	spidev@0{
 		compatible = "spidev";

arch/arm/boot/dts/bcm2708-rpi-cm.dts

@@ -12,10 +12,15 @@
 
 &gpio {
 	spi0_pins: spi0_pins {
-		brcm,pins = <7 8 9 10 11>;
+		brcm,pins = <9 10 11>;
 		brcm,function = <4>; /* alt0 */
 	};
 
+	spi0_cs_pins: spi0_cs_pins {
+		brcm,pins = <8 7>;
+		brcm,function = <1>; /* output */
+	};
+
 	i2c0_pins: i2c0 {
 		brcm,pins = <0 1>;
 		brcm,function = <4>;
@@ -34,7 +39,8 @@
 
 &spi0 {
 	pinctrl-names = "default";
-	pinctrl-0 = <&spi0_pins>;
+	pinctrl-0 = <&spi0_pins &spi0_cs_pins>;
+	cs-gpios = <&gpio 8 1>, <&gpio 7 1>;
 
 	spidev@0{
 		compatible = "spidev";

arch/arm/boot/dts/bcm2709-rpi-2-b.dts

@@ -9,10 +9,15 @@
 
 &gpio {
 	spi0_pins: spi0_pins {
-		brcm,pins = <7 8 9 10 11>;
+		brcm,pins = <9 10 11>;
 		brcm,function = <4>; /* alt0 */
 	};
 
+	spi0_cs_pins: spi0_cs_pins {
+		brcm,pins = <8 7>;
+		brcm,function = <1>; /* output */
+	};
+
 	i2c0_pins: i2c0 {
 		brcm,pins = <0 1>;
 		brcm,function = <4>;
@@ -44,7 +49,8 @@
 
 &spi0 {
 	pinctrl-names = "default";
-	pinctrl-0 = <&spi0_pins>;
+	pinctrl-0 = <&spi0_pins &spi0_cs_pins>;
+	cs-gpios = <&gpio 8 1>, <&gpio 7 1>;
 
 	spidev@0{
 		compatible = "spidev";

arch/arm/boot/dts/overlays/Makefile

@@ -45,6 +45,7 @@ dtb-$(RPI_DT_OVERLAYS) += rpi-sense-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += sdhost-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += spi-bcm2708-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += spi-bcm2835-overlay.dtb
+dtb-$(RPI_DT_OVERLAYS) += spi-gpio35-39-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += tinylcd35-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += uart1-overlay.dtb
 dtb-$(RPI_DT_OVERLAYS) += vga666-overlay.dtb

arch/arm/boot/dts/overlays/README

@@ -519,6 +519,12 @@ Load:   dtoverlay=spi-bcm2835
 Params: <None>
 
 
+Name:   spi-gpio35-39
+Info:   move SPI function block to GPIO 35 to 39
+Load:   dtoverlay=spi-gpio35-39
+Params: <None>
+
+
 Name:   tinylcd35
 Info:   3.5" Color TFT Display by www.tinylcd.com
         Options: Touch, RTC, keypad

arch/arm/boot/dts/overlays/spi-bcm2708-overlay.dts

@@ -1,5 +1,5 @@
 /*
- * Device tree overlay for spi-bcm2835
+ * Device tree overlay to use spi-bcm2708
  */
 
 /dts-v1/;
@@ -15,4 +15,11 @@
 			compatible = "brcm,bcm2708-spi";
 		};
 	};
+
+	fragment@1 {
+		target = <&spi0_cs_pins>;
+		__overlay__ {
+			brcm,function = <4>; /* alt0 */
+		};
+	};
 };

arch/arm/boot/dts/overlays/spi-gpio35-39-overlay.dts

@@ -0,0 +1,31 @@
+/*
+ * Device tree overlay to move spi0 to gpio 35 to 39 on CM
+ */
+
+/dts-v1/;
+/plugin/;
+
+/ {
+	compatible = "brcm,bcm2835", "brcm,bcm2836", "brcm,bcm2708", "brcm,bcm2709";
+
+	fragment@0 {
+		target = <&spi0>;
+		__overlay__ {
+			cs-gpios = <&gpio 36 1>, <&gpio 35 1>;
+		};
+	};
+
+	fragment@1 {
+		target = <&spi0_cs_pins>;
+		__overlay__ {
+			bcrm,pins = <36 35>;
+		};
+	};
+
+	fragment@2 {
+		target = <&spi0_pins>;
+		__overlay__ {
+			bcrm,pins = <37 38 39>;
+		};
+	};
+};