[PATCH v2 10/18] dt-bindings: Document the STM32 pin controller

[Maxime Coquelin <mcoquelin.stm32@xxxxxxxxx>]

This adds documentation of device tree bindings for the
STM32 pin controller.

Signed-off-by: Maxime Coquelin <mcoquelin.stm32@xxxxxxxxx>
---
 .../devicetree/bindings/pinctrl/pinctrl-stm32.txt  | 99 ++++++++++++++++++++++
 1 file changed, 99 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pinctrl/pinctrl-stm32.txt

diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-stm32.txt b/Documentation/devicetree/bindings/pinctrl/pinctrl-stm32.txt
new file mode 100644
index 0000000..0fb5b24
--- /dev/null
+++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-stm32.txt
@@ -0,0 +1,99 @@
+* STM32 GPIO and Pin Mux/Config controller
+
+STMicroelectronics's STM32 MCUs intregrate a GPIO and Pin mux/config hardware
+controller. It controls the input/output settings on the available pins and
+also provides ability to multiplex and configure the output of various on-chip
+controllers onto these pads.
+
+Pin controller node:
+Required properies:
+- compatible	: "st,stm32-pinctrl"
+- #address-cells: The value of this property must be 1
+- #size-cells	: The value of this property must be 1
+- ranges	: defines mapping between pin controller node (parent) to
+  gpio-bank node (children).
+
+GPIO controller/bank node:
+Required properties:
+- gpio-controller : Indicates this device is a GPIO controller
+- #gpio-cells	  : Should be two.
+			The first cell is the pin number
+			The second one is the polarity:
+				- 0 for active high
+				- 1 for active low
+- reg		  : The gpio address range, relative to the pinctrl range
+- st,bank-name	  : Should be a name string for this bank as specified in
+  the datasheet
+
+Optional properties:
+- reset:	  : Reference to the reset controller
+
+Example:
+#include <dt-bindings/pinctrl/pinctrl-stm32.h>
+...
+
+	pin-controller {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "st,stm32-pinctrl";
+		ranges = <0 0x40020000 0x3000>;
+
+		gpioa: gpio@40020000 {
+			gpio-controller;
+			#gpio-cells = <2>;
+			reg = <0x0 0x400>;
+			resets = <&reset_ahb1 0>;
+			st,bank-name = "GPIOA";
+		};
+		...
+		pin-functions nodes follow...
+	};
+
+Contents of function subnode node:
+----------------------------------
+
+Required properties for pin configuration node:
+- st,pins	: Child node with list of pins with configuration.
+
+Below is the format of how each pin conf should look like.
+
+<bank offset altmode pull type speed>
+
+Every PIO is represented with 4 to 6 parameters.
+Each parameter is explained as below.
+
+- bank	  : Should be bank phandle to which this PIO belongs.
+- offset  : Offset in the PIO bank.
+- altmode : Should be mode or alternate function number associated this pin, as
+described in the datasheet (IN, OUT, ALT0...ALT15, ANALOG)
+- pull	  : Should be either NO_PULL, PULL_UP or PULL_DOWN
+- type	  : Should be either PUSH_PULL or OPEN_DRAIN.
+	    Setting it is not needed for IN and ANALOG modes, or alternate
+	    functions acting as inputs.
+- speed	  : Value taken from the datasheet, depending on the function
+(LOW_SPEED, MEDIUM_SPEED, FAST_SPEED, HIGH_SPEED)
+	    Setting it is not needed for IN and ANALOG modes, or alternate
+	    functions acting as inputs.
+
+usart1 {
+	pinctrl_usart1: usart1-0 {
+		st,pins {
+			tx = <&gpioa 9 ALT7 NO_PULL PUSH_PULL LOW_SPEED>;
+			rx = <&gpioa 10 ALT7 NO_PULL PUSH_PULL LOW_SPEED>;
+		};
+	};
+};
+
+adc2 {
+	pinctrl_adc2: adc2-0 {
+		st,pins {
+			adc0 = <&gpioe 4 ANALOG NO_PULL>;
+		};
+	};
+};
+
+usart1: usart@40011000 {
+	...
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_usart1>;
+};
-- 
1.9.1

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