dt-bindings: gpio: pcf857x: Convert to json-schema
Convert the PCF857x-compatible I/O expanders Device Tree binding documentation to json-schema. Document missing compatible values, properties, and gpio hogs. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Rob Herring <robh@kernel.org> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
This commit is contained in:
Geert Uytterhoeven
Bartosz Golaszewski
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cdee1d6222
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d766dfee58
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* PCF857x-compatible I/O expanders
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The PCF857x-compatible chips have "quasi-bidirectional" I/O lines that can be
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driven high by a pull-up current source or driven low to ground. This combines
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the direction and output level into a single bit per line, which can't be read
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back. We can't actually know at initialization time whether a line is configured
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(a) as output and driving the signal low/high, or (b) as input and reporting a
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low/high value, without knowing the last value written since the chip came out
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of reset (if any). The only reliable solution for setting up line direction is
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thus to do it explicitly.
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Required Properties:
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- compatible: should be one of the following.
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- "maxim,max7328": For the Maxim MAX7378
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- "maxim,max7329": For the Maxim MAX7329
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- "nxp,pca8574": For the NXP PCA8574
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- "nxp,pca8575": For the NXP PCA8575
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- "nxp,pca9670": For the NXP PCA9670
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- "nxp,pca9671": For the NXP PCA9671
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- "nxp,pca9672": For the NXP PCA9672
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- "nxp,pca9673": For the NXP PCA9673
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- "nxp,pca9674": For the NXP PCA9674
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- "nxp,pca9675": For the NXP PCA9675
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- "nxp,pcf8574": For the NXP PCF8574
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- "nxp,pcf8574a": For the NXP PCF8574A
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- "nxp,pcf8575": For the NXP PCF8575
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- reg: I2C slave address.
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- gpio-controller: Marks the device node as a gpio controller.
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- #gpio-cells: Should be 2. The first cell is the GPIO number and the second
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cell specifies GPIO flags, as defined in <dt-bindings/gpio/gpio.h>. Only the
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GPIO_ACTIVE_HIGH and GPIO_ACTIVE_LOW flags are supported.
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Optional Properties:
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- lines-initial-states: Bitmask that specifies the initial state of each
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line. When a bit is set to zero, the corresponding line will be initialized to
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the input (pulled-up) state. When the bit is set to one, the line will be
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initialized the low-level output state. If the property is not specified
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all lines will be initialized to the input state.
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The I/O expander can detect input state changes, and thus optionally act as
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an interrupt controller. When the expander interrupt line is connected all the
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following properties must be set. For more information please see the
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interrupt controller device tree bindings documentation available at
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Documentation/devicetree/bindings/interrupt-controller/interrupts.txt.
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- interrupt-controller: Identifies the node as an interrupt controller.
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- #interrupt-cells: Number of cells to encode an interrupt source, shall be 2.
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- interrupts: Interrupt specifier for the controllers interrupt.
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Please refer to gpio.txt in this directory for details of the common GPIO
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bindings used by client devices.
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Example: PCF8575 I/O expander node
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pcf8575: gpio@20 {
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compatible = "nxp,pcf8575";
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reg = <0x20>;
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interrupt-parent = <&irqpin2>;
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interrupts = <3 0>;
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gpio-controller;
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#gpio-cells = <2>;
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interrupt-controller;
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#interrupt-cells = <2>;
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};
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@ -0,0 +1,103 @@
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# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/gpio/nxp,pcf8575.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: PCF857x-compatible I/O expanders
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maintainers:
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- Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
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description:
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The PCF857x-compatible chips have "quasi-bidirectional" I/O lines that can be
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driven high by a pull-up current source or driven low to ground. This
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combines the direction and output level into a single bit per line, which
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can't be read back. We can't actually know at initialization time whether a
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line is configured (a) as output and driving the signal low/high, or (b) as
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input and reporting a low/high value, without knowing the last value written
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since the chip came out of reset (if any). The only reliable solution for
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setting up line direction is thus to do it explicitly.
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properties:
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compatible:
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enum:
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- maxim,max7328
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- maxim,max7329
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- nxp,pca8574
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- nxp,pca8575
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- nxp,pca9670
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- nxp,pca9671
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- nxp,pca9672
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- nxp,pca9673
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- nxp,pca9674
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- nxp,pca9675
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- nxp,pcf8574
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- nxp,pcf8574a
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- nxp,pcf8575
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reg:
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maxItems: 1
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gpio-controller: true
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'#gpio-cells':
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const: 2
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description:
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The first cell is the GPIO number and the second cell specifies GPIO
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flags, as defined in <dt-bindings/gpio/gpio.h>. Only the GPIO_ACTIVE_HIGH
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and GPIO_ACTIVE_LOW flags are supported.
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lines-initial-states:
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$ref: /schemas/types.yaml#/definitions/uint32
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description:
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Bitmask that specifies the initial state of each line.
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When a bit is set to zero, the corresponding line will be initialized to
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the input (pulled-up) state.
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When the bit is set to one, the line will be initialized to the
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low-level output state.
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If the property is not specified all lines will be initialized to the
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input state.
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interrupts:
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maxItems: 1
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interrupt-controller: true
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'#interrupt-cells':
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const: 2
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wakeup-source: true
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patternProperties:
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"^(.+-hog(-[0-9]+)?)$":
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type: object
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required:
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- gpio-hog
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required:
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- compatible
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- reg
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- gpio-controller
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- '#gpio-cells'
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additionalProperties: false
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examples:
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- |
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i2c {
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#address-cells = <1>;
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#size-cells = <0>;
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pcf8575: gpio@20 {
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compatible = "nxp,pcf8575";
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reg = <0x20>;
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interrupt-parent = <&irqpin2>;
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interrupts = <3 0>;
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gpio-controller;
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#gpio-cells = <2>;
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interrupt-controller;
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#interrupt-cells = <2>;
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};
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};
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