gpio: add gpio offset in gpio range cells property

Add gpio offset into "gpio-range-cells" property. It's used to support
sparse pinctrl range in gpio chip.

Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/gpio/gpio.txt

@@ -98,7 +98,7 @@ announce the pinrange to the pin ctrl subsystem. For example,
 		compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank";
 		reg = <0x1460 0x18>;
 		gpio-controller;
-		gpio-ranges = <&pinctrl1 20 10>, <&pinctrl2 50 20>;
+		gpio-ranges = <&pinctrl1 0 20 10>, <&pinctrl2 10 50 20>;
 
     }
 
@@ -107,8 +107,8 @@ where,
 
    Next values specify the base pin and number of pins for the range
    handled by 'qe_pio_e' gpio. In the given example from base pin 20 to
-   pin 29 under pinctrl1 and pin 50 to pin 69 under pinctrl2 is handled
-   by this gpio controller.
+   pin 29 under pinctrl1 with gpio offset 0 and pin 50 to pin 69 under
+   pinctrl2 with gpio offset 10 is handled by this gpio controller.
 
 The pinctrl node must have "#gpio-range-cells" property to show number of
 arguments to pass with phandle from gpio controllers node.

arch/arm/boot/dts/spear1310.dtsi

@@ -89,7 +89,7 @@
 		pinmux: pinmux@e0700000 {
 			compatible = "st,spear1310-pinmux";
 			reg = <0xe0700000 0x1000>;
-			#gpio-range-cells = <2>;
+			#gpio-range-cells = <3>;
 		};
 
 		apb {
@@ -212,7 +212,7 @@
 				interrupt-controller;
 				gpio-controller;
 				#gpio-cells = <2>;
-				gpio-ranges = <&pinmux 0 246>;
+				gpio-ranges = <&pinmux 0 0 246>;
 				status = "disabled";
 
 				st-plgpio,ngpio = <246>;

arch/arm/boot/dts/spear1340.dtsi

@@ -63,7 +63,7 @@
 		pinmux: pinmux@e0700000 {
 			compatible = "st,spear1340-pinmux";
 			reg = <0xe0700000 0x1000>;
-			#gpio-range-cells = <2>;
+			#gpio-range-cells = <3>;
 		};
 
 		pwm: pwm@e0180000 {
@@ -127,7 +127,7 @@
 				interrupt-controller;
 				gpio-controller;
 				#gpio-cells = <2>;
-				gpio-ranges = <&pinmux 0 252>;
+				gpio-ranges = <&pinmux 0 0 252>;
 				status = "disabled";
 
 				st-plgpio,ngpio = <250>;

arch/arm/boot/dts/spear310.dtsi

@@ -25,7 +25,7 @@
 		pinmux: pinmux@b4000000 {
 			compatible = "st,spear310-pinmux";
 			reg = <0xb4000000 0x1000>;
-			#gpio-range-cells = <2>;
+			#gpio-range-cells = <3>;
 		};
 
 		fsmc: flash@44000000 {
@@ -102,7 +102,7 @@
 				interrupt-controller;
 				gpio-controller;
 				#gpio-cells = <2>;
-				gpio-ranges = <&pinmux 0 102>;
+				gpio-ranges = <&pinmux 0 0 102>;
 				status = "disabled";
 
 				st-plgpio,ngpio = <102>;

arch/arm/boot/dts/spear320.dtsi

@@ -24,7 +24,7 @@
 		pinmux: pinmux@b3000000 {
 			compatible = "st,spear320-pinmux";
 			reg = <0xb3000000 0x1000>;
-			#gpio-range-cells = <2>;
+			#gpio-range-cells = <3>;
 		};
 
 		clcd@90000000 {
@@ -130,7 +130,7 @@
 				interrupt-controller;
 				gpio-controller;
 				#gpio-cells = <2>;
-				gpio-ranges = <&pinmux 0 102>;
+				gpio-ranges = <&pinmux 0 0 102>;
 				status = "disabled";
 
 				st-plgpio,ngpio = <102>;

drivers/gpio/gpiolib-of.c

@@ -203,22 +203,11 @@ static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
 		if (!pctldev)
 			break;
 
-		/*
-		 * This assumes that the n GPIO pins are consecutive in the
-		 * GPIO number space, and that the pins are also consecutive
-		 * in their local number space. Currently it is not possible
-		 * to add different ranges for one and the same GPIO chip,
-		 * as the code assumes that we have one consecutive range
-		 * on both, mapping 1-to-1.
-		 *
-		 * TODO: make the OF bindings handle multiple sparse ranges
-		 * on the same GPIO chip.
-		 */
 		ret = gpiochip_add_pin_range(chip,
 					     pinctrl_dev_get_devname(pctldev),
-					     0, /* offset in gpiochip */
 					     pinspec.args[0],
-					     pinspec.args[1]);
+					     pinspec.args[1],
+					     pinspec.args[2]);
 
 		if (ret)
 			break;