@@ -82,3 +82,61 @@ gpiom1: gpio@0 {
reg = <0>;
spi-max-frequency = <1000000>;
};
+
+Pull-up configuration
+=====================
+
+If pins are used as output, they can also be configured with pull-ups. This is
+done with pinctrl.
+
+Please refer file <devicetree/bindings/pinctrl/pinctrl-bindings.txt>
+for details of the common pinctrl bindings used by client devices,
+including the meaning of the phrase "pin configuration node".
+
+Optional Pinmux properties:
+--------------------------
+Following properties are required if default setting of pins are required
+at boot.
+- pinctrl-names: A pinctrl state named per <pinctrl-binding.txt>.
+- pinctrl[0...n]: Properties to contain the phandle for pinctrl states per
+ <pinctrl-binding.txt>.
+
+The pin configurations are defined as child of the pinctrl states node. Each
+sub-node have following properties:
+
+Required properties:
+------------------
+- pins: List of pins. Valid values of pins properties are:
+ gpio0 ... gpio7 for the devices with 8 GPIO pins and
+ gpio0 ... gpio15 for the devices with 16 GPIO pins.
+
+Optional properties:
+-------------------
+The following optional property is defined in the pinmux DT binding document
+<pinctrl-bindings.txt>. Absence of this property will leave the configuration
+in its default state.
+ bias-pull-up
+
+Example with pinctrl to pull-up output pins:
+gpio21: gpio@21 {
+ compatible = "microchip,mcp23017";
+ gpio-controller;
+ #gpio-cells = <0x2>;
+ reg = <0x21>;
+ interrupt-parent = <&socgpio>;
+ interrupts = <0x17 0x8>;
+ interrupt-names = "mcp23017@21 irq";
+ interrupt-controller;
+ #interrupt-cells = <0x2>;
+ microchip,irq-mirror;
+ pinctrl-names = "default";
+ pinctrl-0 = <&i2cgpio0irq &gpio21pullups>;
+
+ gpio21pullups: pinmux {
+ pins = "gpio0", "gpio1", "gpio2", "gpio3",
+ "gpio4", "gpio5", "gpio6", "gpio7",
+ "gpio8", "gpio9", "gpio10", "gpio11",
+ "gpio12", "gpio13", "gpio14", "gpio15";
+ bias-pull-up;
+ };
+};
The mcp23s08 driver moved to pinctrl recently. It accepts the bias-pull-up pinctrl property since then. This updates the binding doc to reflect that. Thanks to Sebastian Reichel for the working example. Signed-off-by: Lars Poeschel <poeschel@lemonage.de> --- .../bindings/pinctrl/pinctrl-mcp23s08.txt | 58 ++++++++++++++++++++++ 1 file changed, 58 insertions(+)