1Pinctrl-based I2C Bus DeMux
2
3This binding describes an I2C bus demultiplexer that uses pin multiplexing to
4route the I2C signals, and represents the pin multiplexing configuration using
5the pinctrl device tree bindings. This may be used to select one I2C IP core at
6runtime which may have a better feature set for a given task than another I2C
7IP core on the SoC. The most simple example is to fall back to GPIO bitbanging
8if your current runtime configuration hits an errata of the internal IP core.
9
10    +-------------------------------+
11    | SoC                           |
12    |                               |   +-----+  +-----+
13    |   +------------+              |   | dev |  | dev |
14    |   |I2C IP Core1|--\           |   +-----+  +-----+
15    |   +------------+   \-------+  |      |        |
16    |                    |Pinctrl|--|------+--------+
17    |   +------------+   +-------+  |
18    |   |I2C IP Core2|--/           |
19    |   +------------+              |
20    |                               |
21    +-------------------------------+
22
23Required properties:
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
28		parents.
29
30Furthermore, I2C mux properties and child nodes. See i2c-mux.txt in this
31directory.
32
33Example:
34
35Here is a snipplet for a bus to be demuxed. It contains various i2c clients for
36HDMI, so the bus is named "i2c-hdmi":
37
38	i2chdmi: i2c@8 {
39
40		compatible = "i2c-demux-pinctrl";
41		i2c-parent = <&gpioi2c>, <&iic2>, <&i2c2>;
42		i2c-bus-name = "i2c-hdmi";
43		#address-cells = <1>;
44		#size-cells = <0>;
45
46		ak4643: sound-codec@12 {
47			compatible = "asahi-kasei,ak4643";
48
49			#sound-dai-cells = <0>;
50			reg = <0x12>;
51		};
52
53		composite-in@20 {
54			compatible = "adi,adv7180";
55			reg = <0x20>;
56			remote = <&vin1>;
57
58			port {
59				adv7180: endpoint {
60					bus-width = <8>;
61					remote-endpoint = <&vin1ep0>;
62				};
63			};
64		};
65
66		hdmi@39 {
67			compatible = "adi,adv7511w";
68			reg = <0x39>;
69			interrupt-parent = <&gpio1>;
70			interrupts = <15 IRQ_TYPE_LEVEL_LOW>;
71
72			adi,input-depth = <8>;
73			adi,input-colorspace = "rgb";
74			adi,input-clock = "1x";
75			adi,input-style = <1>;
76			adi,input-justification = "evenly";
77
78			ports {
79				#address-cells = <1>;
80				#size-cells = <0>;
81
82				port@0 {
83					reg = <0>;
84					adv7511_in: endpoint {
85						remote-endpoint = <&du_out_lvds0>;
86					};
87				};
88
89				port@1 {
90					reg = <1>;
91					adv7511_out: endpoint {
92						remote-endpoint = <&hdmi_con>;
93					};
94				};
95			};
96		};
97	};
98
99And for clarification, here are the snipplets for the i2c-parents:
100
101	gpioi2c: i2c@9 {
102		#address-cells = <1>;
103		#size-cells = <0>;
104		compatible = "i2c-gpio";
105		status = "disabled";
106		gpios = <&gpio5 6 GPIO_ACTIVE_HIGH /* sda */
107			 &gpio5 5 GPIO_ACTIVE_HIGH /* scl */
108			>;
109		i2c-gpio,delay-us = <5>;
110	};
111
112...
113
114&i2c2	{
115	pinctrl-0 = <&i2c2_pins>;
116	pinctrl-names = "i2c-hdmi";
117
118	clock-frequency = <100000>;
119};
120
121...
122
123&iic2	{
124	pinctrl-0 = <&iic2_pins>;
125	pinctrl-names = "i2c-hdmi";
126
127	clock-frequency = <100000>;
128};
129
130Please note:
131
132- pinctrl properties for the parent I2C controllers need a pinctrl state
133  with the same name as i2c-bus-name, not "default"!
134
135- the i2c masters must have their status "disabled". This driver will
136  enable them at runtime when needed.
137