xref: /OK3568_Linux_fs/kernel/Documentation/devicetree/bindings/i2c/i2c-mux.txt (revision 4882a59341e53eb6f0b4789bf948001014eff981)
1*4882a593SmuzhiyunCommon i2c bus multiplexer/switch properties.
2*4882a593Smuzhiyun
3*4882a593SmuzhiyunAn i2c bus multiplexer/switch will have several child busses that are
4*4882a593Smuzhiyunnumbered uniquely in a device dependent manner.  The nodes for an i2c bus
5*4882a593Smuzhiyunmultiplexer/switch will have one child node for each child bus.
6*4882a593Smuzhiyun
7*4882a593SmuzhiyunOptional properties:
8*4882a593Smuzhiyun- #address-cells = <1>;
9*4882a593Smuzhiyun   This property is required if the i2c-mux child node does not exist.
10*4882a593Smuzhiyun
11*4882a593Smuzhiyun- #size-cells = <0>;
12*4882a593Smuzhiyun   This property is required if the i2c-mux child node does not exist.
13*4882a593Smuzhiyun
14*4882a593Smuzhiyun- i2c-mux
15*4882a593Smuzhiyun   For i2c multiplexers/switches that have child nodes that are a mixture
16*4882a593Smuzhiyun   of both i2c child busses and other child nodes, the 'i2c-mux' subnode
17*4882a593Smuzhiyun   can be used for populating the i2c child busses.  If an 'i2c-mux'
18*4882a593Smuzhiyun   subnode is present, only subnodes of this will be considered as i2c
19*4882a593Smuzhiyun   child busses.
20*4882a593Smuzhiyun
21*4882a593SmuzhiyunRequired properties for the i2c-mux child node:
22*4882a593Smuzhiyun- #address-cells = <1>;
23*4882a593Smuzhiyun- #size-cells = <0>;
24*4882a593Smuzhiyun
25*4882a593SmuzhiyunRequired properties for i2c child bus nodes:
26*4882a593Smuzhiyun- #address-cells = <1>;
27*4882a593Smuzhiyun- #size-cells = <0>;
28*4882a593Smuzhiyun- reg : The sub-bus number.
29*4882a593Smuzhiyun
30*4882a593SmuzhiyunOptional properties for i2c child bus nodes:
31*4882a593Smuzhiyun- Other properties specific to the multiplexer/switch hardware.
32*4882a593Smuzhiyun- Child nodes conforming to i2c bus binding
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun
35*4882a593SmuzhiyunExample :
36*4882a593Smuzhiyun
37*4882a593Smuzhiyun	/*
38*4882a593Smuzhiyun	   An NXP pca9548 8 channel I2C multiplexer at address 0x70
39*4882a593Smuzhiyun	   with two NXP pca8574 GPIO expanders attached, one each to
40*4882a593Smuzhiyun	   ports 3 and 4.
41*4882a593Smuzhiyun	 */
42*4882a593Smuzhiyun
43*4882a593Smuzhiyun	mux@70 {
44*4882a593Smuzhiyun		compatible = "nxp,pca9548";
45*4882a593Smuzhiyun		reg = <0x70>;
46*4882a593Smuzhiyun		#address-cells = <1>;
47*4882a593Smuzhiyun		#size-cells = <0>;
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun		i2c@3 {
50*4882a593Smuzhiyun			#address-cells = <1>;
51*4882a593Smuzhiyun			#size-cells = <0>;
52*4882a593Smuzhiyun			reg = <3>;
53*4882a593Smuzhiyun
54*4882a593Smuzhiyun			gpio1: gpio@38 {
55*4882a593Smuzhiyun				compatible = "nxp,pca8574";
56*4882a593Smuzhiyun				reg = <0x38>;
57*4882a593Smuzhiyun				#gpio-cells = <2>;
58*4882a593Smuzhiyun				gpio-controller;
59*4882a593Smuzhiyun			};
60*4882a593Smuzhiyun		};
61*4882a593Smuzhiyun		i2c@4 {
62*4882a593Smuzhiyun			#address-cells = <1>;
63*4882a593Smuzhiyun			#size-cells = <0>;
64*4882a593Smuzhiyun			reg = <4>;
65*4882a593Smuzhiyun
66*4882a593Smuzhiyun			gpio2: gpio@38 {
67*4882a593Smuzhiyun				compatible = "nxp,pca8574";
68*4882a593Smuzhiyun				reg = <0x38>;
69*4882a593Smuzhiyun				#gpio-cells = <2>;
70*4882a593Smuzhiyun				gpio-controller;
71*4882a593Smuzhiyun			};
72*4882a593Smuzhiyun		};
73*4882a593Smuzhiyun	};
74