Add device tree bindings documentation for Renesas RZ/A1 gpio and pin
controller.
Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
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.../bindings/pinctrl/renesas,rza1-pinctrl.txt | 114 +++++++++++++++++++++
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create mode 100644 Documentation/devicetree/bindings/pinctrl/renesas,rza1-pinctrl.txt
diff --git a/Documentation/devicetree/bindings/pinctrl/renesas,rza1-pinctrl.txt b/Documentation/devicetree/bindings/pinctrl/renesas,rza1-pinctrl.txt
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+Renesas RZ/A1 combined Pin and GPIO controller
+
+Renesas SoCs of RZ/A1 family feature a combined Pin and GPIO controller
+hardware controller, named "Ports" in the hardware reference manual.
+Pin multiplexing and GPIO configuration is performed on a per-pin base
+writing configuration values to per-port register sets.
+Each "port" features up to 16 pins, each of them configurable for GPIO
+function (port mode) or in alternate function mode.
+Up to 8 different alternate function modes exist for each single pin.
+
+Pin controller node
+-------------------
+
+Required properties:
+ - compatible
+ this shall be "renesas,r7s72100-ports".
+
+ - #pinctrl-cells
+ as defined by pinctrl-bindings.txt, this is the number
+ of cells (in addition to pin index) required to configure a single pin.
+ Shall be set to 1.
+
+ - reg
+ address base and length of the memory area where pin controller
+ hardware is mapped to.
+
+Example:
+Pin controller node for RZ/A1H SoC (r7s72100)
+
+pinctrl: pinctrl@fcfe3000 {
+ compatible = "renesas,r7s72100-ports";
+
+ #pinctrl-cells = <1>;
+
+ reg = <0xfcfe3000 0x4248>;
+};
+
+Sub-nodes
+---------
+
+The child nodes of the pin controller node describe a pin multiplexing
+function or a gpio controller alternatively.
+
+- Pin multiplexing sub-nodes:
+ A pin multiplexing sub-node describes how to configure a set of
+ (or a single) pin in some desired alternate function mode.
+ A single sub-node may define several pin configurations groups.
+
+ Required properties:
+ - renesas,pins
+ describes an array of pin multiplexing configurations.
+ When a pin has to be configured in alternate function mode, use this
+ property to identify the pin by its global index, and provide its
+ alternate function configuration description along with it.
+ When multiple pins are required to be configured as part of the same
+ alternate function (odds are single-pin alternate functions exist) they
+ shall be specified as members of the same argument list of a single
+ "renesas-pins" property.
+ Helper macros to ease calculating the pin index from its position
+ (port where it sits on and pin offset), and alternate function
+ configuration options are provided in pin controller header file at:
+ include/dt-bindings/pinctrl/r7s72100-pinctrl.h
+
+ Example:
+ A serial communication interface with a TX output pin and a RX input pin.
+ The RX pin requires input capabilities.
+
+ &pinctrl {
+ scif2_pins: serial2 {
+ renesas,pins = <PIN(3, 0) 6>,
+ <PIN(3, 2) (4 | INPUT_EN)>;
+ };
+ }
+
+ Pin #0 on port #3 is configured in alternate function #6.
+ Pin #2 on port #3 is configured in alternate function #4 with input enabled.
+
+- GPIO controller sub-nodes:
+ Each port of r7s72100 pin controller hardware is itself a gpio controller.
+ Different SoCs have different number of available pins per port, but
+ generally speaking, each of them can be configured in GPIO ("port") mode
+ on this hardware.
+ Describe gpio-controllers using sub-nodes with the following properties.
+
+ Required properties:
+ - gpio-controller
+ empty property as defined by gpio bindings documentation.
+ - #gpio-cells
+ number of cells required to identify and configure a GPIO.
+ Shall be 2.
+ - gpio-ranges
+ Describes a gpio controller specifying its specific pin base, the pin
+ base in the global pin numbering space, and the number of controlled
+ pins, as defined by gpio bindings documentation. Refer to this file
+ for a more detailed description.
+
+ Example:
+ A gpio controller node, controlling 16 pins indexed starting from 0.
+ The gpio controller base in the global pin indexing space is pin 48, thus
+ pins [0 - 15] on this controller map to pins [48 - 63] in the global pin
+ indexing space.
+
+ port3: gpio@3 {
+ gpio-controller;
+ #gpio-cells = <2>;
+ gpio-ranges = <&pinctrl 0 48 16>;
+ };
+
+ A device node willing to use pins controlled by this gpio controller, shall
+ refer to it as follows:
+
+ led1 {
+ gpios = <&port3 10 GPIO_ACTIVE_LOW>;
+ };
--
2.7.4
