cbc59e26e9
Add pinctrl device tree binding documentation for the General Purpose Pin Mapping module of the Conexant CX92755 SoC. Signed-off-by: Baruch Siach <baruch@tkos.co.il> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
87 lines
2.9 KiB
Plaintext
87 lines
2.9 KiB
Plaintext
Conexant Digicolor CX92755 General Purpose Pin Mapping
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This document describes the device tree binding of the pin mapping hardware
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modules in the Conexant Digicolor CX92755 SoCs. The CX92755 in one of the
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Digicolor series of SoCs.
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=== Pin Controller Node ===
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Required Properties:
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- compatible: Must be "cnxt,cx92755-pinctrl"
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- reg: Base address of the General Purpose Pin Mapping register block and the
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size of the block.
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- gpio-controller: Marks the device node as a GPIO controller.
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- #gpio-cells: Must be <2>. The first cell is the pin number and the
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second cell is used to specify flags. See include/dt-bindings/gpio/gpio.h
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for possible values.
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For example, the following is the bare minimum node:
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pinctrl: pinctrl@f0000e20 {
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compatible = "cnxt,cx92755-pinctrl";
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reg = <0xf0000e20 0x100>;
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gpio-controller;
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#gpio-cells = <2>;
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};
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As a pin controller device, in addition to the required properties, this node
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should also contain the pin configuration nodes that client devices reference,
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if any.
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For a general description of GPIO bindings, please refer to ../gpio/gpio.txt.
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=== Pin Configuration Node ===
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Each pin configuration node is a sub-node of the pin controller node and is a
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container of an arbitrary number of subnodes, called pin group nodes in this
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document.
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Please refer to the pinctrl-bindings.txt in this directory for details of the
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common pinctrl bindings used by client devices, including the definition of a
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"pin configuration node".
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=== Pin Group Node ===
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A pin group node specifies the desired pin mux for an arbitrary number of
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pins. The name of the pin group node is optional and not used.
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A pin group node only affects the properties specified in the node, and has no
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effect on any properties that are omitted.
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The pin group node accepts a subset of the generic pin config properties. For
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details generic pin config properties, please refer to pinctrl-bindings.txt
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and <include/linux/pinctrl/pinconfig-generic.h>.
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Required Pin Group Node Properties:
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- pins: Multiple strings. Specifies the name(s) of one or more pins to be
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configured by this node. The format of a pin name string is "GP_xy", where x
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is an uppercase character from 'A' to 'R', and y is a digit from 0 to 7.
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- function: String. Specifies the pin mux selection. Values must be one of:
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"gpio", "client_a", "client_b", "client_c"
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Example:
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pinctrl: pinctrl@f0000e20 {
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compatible = "cnxt,cx92755-pinctrl";
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reg = <0xf0000e20 0x100>;
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uart0_default: uart0_active {
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data_signals {
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pins = "GP_O0", "GP_O1";
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function = "client_b";
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};
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};
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};
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uart0: uart@f0000740 {
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compatible = "cnxt,cx92755-usart";
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...
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pinctrl-0 = <&uart0_default>;
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pinctrl-names = "default";
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};
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In the example above, a single pin group configuration node defines the
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"client select" for the Rx and Tx signals of uart0. The uart0 node references
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that pin configuration node using the &uart0_default phandle.
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