projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| bc45449b DD |
1 | Common i2c bus multiplexer/switch properties. |
| 2 | ||
| 3 | An i2c bus multiplexer/switch will have several child busses that are | |
| 4 | numbered uniquely in a device dependent manner. The nodes for an i2c bus | |
| 374f8436 | 5 | multiplexer/switch will have one child node for each child bus. |
| bc45449b | 6 | |
| 374f8436 PR |
7 | Optional properties: |
| 8 | - #address-cells = <1>; | |
| 9 | This property is required is the i2c-mux child node does not exist. | |
| 10 | ||
| 11 | - #size-cells = <0>; | |
| 12 | This property is required is the i2c-mux child node does not exist. | |
| 13 | ||
| 14 | - i2c-mux | |
| 15 | For i2c multiplexers/switches that have child nodes that are a mixture | |
| 16 | of both i2c child busses and other child nodes, the 'i2c-mux' subnode | |
| 17 | can be used for populating the i2c child busses. If an 'i2c-mux' | |
| 18 | subnode is present, only subnodes of this will be considered as i2c | |
| 19 | child busses. | |
| 20 | ||
| 21 | Required properties for the i2c-mux child node: | |
| bc45449b DD |
22 | - #address-cells = <1>; |
| 23 | - #size-cells = <0>; | |
| 24 | ||
| 374f8436 | 25 | Required properties for i2c child bus nodes: |
| bc45449b DD |
26 | - #address-cells = <1>; |
| 27 | - #size-cells = <0>; | |
| 28 | - reg : The sub-bus number. | |
| 29 | ||
| 374f8436 | 30 | Optional properties for i2c child bus nodes: |
| bc45449b DD |
31 | - Other properties specific to the multiplexer/switch hardware. |
| 32 | - Child nodes conforming to i2c bus binding | |
| 33 | ||
| 34 | ||
| 35 | Example : | |
| 36 | ||
| 37 | /* | |
| 38 | An NXP pca9548 8 channel I2C multiplexer at address 0x70 | |
| 39 | with two NXP pca8574 GPIO expanders attached, one each to | |
| 40 | ports 3 and 4. | |
| 41 | */ | |
| 42 | ||
| 43 | mux@70 { | |
| 44 | compatible = "nxp,pca9548"; | |
| 45 | reg = <0x70>; | |
| 46 | #address-cells = <1>; | |
| 47 | #size-cells = <0>; | |
| 48 | ||
| 49 | i2c@3 { | |
| 50 | #address-cells = <1>; | |
| 51 | #size-cells = <0>; | |
| 52 | reg = <3>; | |
| 53 | ||
| 54 | gpio1: gpio@38 { | |
| 55 | compatible = "nxp,pca8574"; | |
| 56 | reg = <0x38>; | |
| 57 | #gpio-cells = <2>; | |
| 58 | gpio-controller; | |
| 59 | }; | |
| 60 | }; | |
| 61 | i2c@4 { | |
| 62 | #address-cells = <1>; | |
| 63 | #size-cells = <0>; | |
| 64 | reg = <4>; | |
| 65 | ||
| 66 | gpio2: gpio@38 { | |
| 67 | compatible = "nxp,pca8574"; | |
| 68 | reg = <0x38>; | |
| 69 | #gpio-cells = <2>; | |
| 70 | gpio-controller; | |
| 71 | }; | |
| 72 | }; | |
| 73 | }; |