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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt | |
parent | Initial commit. (diff) | |
download | linux-upstream/5.10.209.tar.xz linux-upstream/5.10.209.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt b/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt new file mode 100644 index 000000000..81b5d5508 --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt @@ -0,0 +1,135 @@ +Pinctrl-based I2C Bus DeMux + +This binding describes an I2C bus demultiplexer that uses pin multiplexing to +route the I2C signals, and represents the pin multiplexing configuration using +the pinctrl device tree bindings. This may be used to select one I2C IP core at +runtime which may have a better feature set for a given task than another I2C +IP core on the SoC. The most simple example is to fall back to GPIO bitbanging +if your current runtime configuration hits an errata of the internal IP core. + + +-------------------------------+ + | SoC | + | | +-----+ +-----+ + | +------------+ | | dev | | dev | + | |I2C IP Core1|--\ | +-----+ +-----+ + | +------------+ \-------+ | | | + | |Pinctrl|--|------+--------+ + | +------------+ +-------+ | + | |I2C IP Core2|--/ | + | +------------+ | + | | + +-------------------------------+ + +Required properties: +- compatible: "i2c-demux-pinctrl" +- i2c-parent: List of phandles of I2C masters available for selection. The first + one will be used as default. +- i2c-bus-name: The name of this bus. Also needed as pinctrl-name for the I2C + parents. + +Furthermore, I2C mux properties and child nodes. See i2c-mux.txt in this +directory. + +Example: + +Here is a snipplet for a bus to be demuxed. It contains various i2c clients for +HDMI, so the bus is named "i2c-hdmi": + + i2chdmi: i2c@8 { + + compatible = "i2c-demux-pinctrl"; + i2c-parent = <&gpioi2c>, <&iic2>, <&i2c2>; + i2c-bus-name = "i2c-hdmi"; + #address-cells = <1>; + #size-cells = <0>; + + ak4643: sound-codec@12 { + compatible = "asahi-kasei,ak4643"; + + #sound-dai-cells = <0>; + reg = <0x12>; + }; + + composite-in@20 { + compatible = "adi,adv7180"; + reg = <0x20>; + remote = <&vin1>; + + port { + adv7180: endpoint { + bus-width = <8>; + remote-endpoint = <&vin1ep0>; + }; + }; + }; + + hdmi@39 { + compatible = "adi,adv7511w"; + reg = <0x39>; + interrupt-parent = <&gpio1>; + interrupts = <15 IRQ_TYPE_LEVEL_LOW>; + + adi,input-depth = <8>; + adi,input-colorspace = "rgb"; + adi,input-clock = "1x"; + adi,input-style = <1>; + adi,input-justification = "evenly"; + + ports { + #address-cells = <1>; + #size-cells = <0>; + + port@0 { + reg = <0>; + adv7511_in: endpoint { + remote-endpoint = <&du_out_lvds0>; + }; + }; + + port@1 { + reg = <1>; + adv7511_out: endpoint { + remote-endpoint = <&hdmi_con>; + }; + }; + }; + }; + }; + +And for clarification, here are the snipplets for the i2c-parents: + + gpioi2c: i2c@9 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "i2c-gpio"; + gpios = <&gpio5 6 GPIO_ACTIVE_HIGH /* sda */ + &gpio5 5 GPIO_ACTIVE_HIGH /* scl */ + >; + i2c-gpio,delay-us = <5>; + }; + +... + +&i2c2 { + pinctrl-0 = <&i2c2_pins>; + pinctrl-names = "i2c-hdmi"; + + clock-frequency = <100000>; +}; + +... + +&iic2 { + pinctrl-0 = <&iic2_pins>; + pinctrl-names = "i2c-hdmi"; + + clock-frequency = <100000>; +}; + +Please note: + +- pinctrl properties for the parent I2C controllers need a pinctrl state + with the same name as i2c-bus-name, not "default"! + +- the i2c masters must have their status "disabled". This driver will + enable them at runtime when needed. |