1 Pinctrl-based I2C Bus DeMux
3 This binding describes an I2C bus demultiplexer that uses pin multiplexing to
4 route the I2C signals, and represents the pin multiplexing configuration using
5 the pinctrl device tree bindings. This may be used to select one I2C IP core at
6 runtime which may have a better feature set for a given task than another I2C
7 IP core on the SoC. The most simple example is to fall back to GPIO bitbanging
8 if your current runtime configuration hits an errata of the internal IP core.
10 +-------------------------------+
13 | +------------+ | | dev | | dev |
14 | |I2C IP Core1|--\ | +-----+ +-----+
15 | +------------+ \-------+ | | |
16 | |Pinctrl|--|------+--------+
17 | +------------+ +-------+ |
21 +-------------------------------+
24 - compatible: "i2c-demux-pinctrl"
25 - i2c-parent: List of phandles of I2C masters available for selection. The first
26 one will be used as default.
27 - i2c-bus-name: The name of this bus. Also needed as pinctrl-name for the I2C
30 Furthermore, I2C mux properties and child nodes. See mux.txt in this directory.
34 Here is a snipplet for a bus to be demuxed. It contains various i2c clients for
35 HDMI, so the bus is named "i2c-hdmi":
39 compatible = "i2c-demux-pinctrl";
40 i2c-parent = <&gpioi2c>, <&iic2>, <&i2c2>;
41 i2c-bus-name = "i2c-hdmi";
45 ak4643: sound-codec@12 {
46 compatible = "asahi-kasei,ak4643";
48 #sound-dai-cells = <0>;
53 compatible = "adi,adv7180";
60 remote-endpoint = <&vin1ep0>;
66 compatible = "adi,adv7511w";
68 interrupt-parent = <&gpio1>;
69 interrupts = <15 IRQ_TYPE_LEVEL_LOW>;
71 adi,input-depth = <8>;
72 adi,input-colorspace = "rgb";
73 adi,input-clock = "1x";
74 adi,input-style = <1>;
75 adi,input-justification = "evenly";
83 adv7511_in: endpoint {
84 remote-endpoint = <&du_out_lvds0>;
90 adv7511_out: endpoint {
91 remote-endpoint = <&hdmi_con>;
98 And for clarification, here are the snipplets for the i2c-parents:
101 #address-cells = <1>;
103 compatible = "i2c-gpio";
105 gpios = <&gpio5 6 GPIO_ACTIVE_HIGH /* sda */
106 &gpio5 5 GPIO_ACTIVE_HIGH /* scl */
108 i2c-gpio,delay-us = <5>;
114 pinctrl-0 = <&i2c2_pins>;
115 pinctrl-names = "i2c-hdmi";
117 clock-frequency = <100000>;
123 pinctrl-0 = <&iic2_pins>;
124 pinctrl-names = "i2c-hdmi";
126 clock-frequency = <100000>;
131 - pinctrl properties for the parent I2C controllers need a pinctrl state
132 with the same name as i2c-bus-name, not "default"!
134 - the i2c masters must have their status "disabled". This driver will
135 enable them at runtime when needed.