diff options
| -rw-r--r-- | Documentation/devicetree/bindings/i2c/mux.txt | 60 | ||||
| -rw-r--r-- | drivers/i2c/i2c-mux.c | 23 |
2 files changed, 83 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/i2c/mux.txt b/Documentation/devicetree/bindings/i2c/mux.txt new file mode 100644 index 000000000000..af84cce5cd7b --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/mux.txt @@ -0,0 +1,60 @@ +Common i2c bus multiplexer/switch properties. + +An i2c bus multiplexer/switch will have several child busses that are +numbered uniquely in a device dependent manner. The nodes for an i2c bus +multiplexer/switch will have one child node for each child +bus. + +Required properties: +- #address-cells = <1>; +- #size-cells = <0>; + +Required properties for child nodes: +- #address-cells = <1>; +- #size-cells = <0>; +- reg : The sub-bus number. + +Optional properties for child nodes: +- Other properties specific to the multiplexer/switch hardware. +- Child nodes conforming to i2c bus binding + + +Example : + + /* + An NXP pca9548 8 channel I2C multiplexer at address 0x70 + with two NXP pca8574 GPIO expanders attached, one each to + ports 3 and 4. + */ + + mux@70 { + compatible = "nxp,pca9548"; + reg = <0x70>; + #address-cells = <1>; + #size-cells = <0>; + + i2c@3 { + #address-cells = <1>; + #size-cells = <0>; + reg = <3>; + + gpio1: gpio@38 { + compatible = "nxp,pca8574"; + reg = <0x38>; + #gpio-cells = <2>; + gpio-controller; + }; + }; + i2c@4 { + #address-cells = <1>; + #size-cells = <0>; + reg = <4>; + + gpio2: gpio@38 { + compatible = "nxp,pca8574"; + reg = <0x38>; + #gpio-cells = <2>; + gpio-controller; + }; + }; + }; diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c index 26ab31dd742b..1038c381aea5 100644 --- a/drivers/i2c/i2c-mux.c +++ b/drivers/i2c/i2c-mux.c @@ -24,6 +24,8 @@ #include <linux/slab.h> #include <linux/i2c.h> #include <linux/i2c-mux.h> +#include <linux/of.h> +#include <linux/of_i2c.h> /* multiplexer per channel data */ struct i2c_mux_priv { @@ -125,6 +127,25 @@ struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent, priv->adap.algo_data = priv; priv->adap.dev.parent = &parent->dev; + /* + * Try to populate the mux adapter's of_node, expands to + * nothing if !CONFIG_OF. + */ + if (mux_dev->of_node) { + struct device_node *child; + u32 reg; + + for_each_child_of_node(mux_dev->of_node, child) { + ret = of_property_read_u32(child, "reg", ®); + if (ret) + continue; + if (chan_id == reg) { + priv->adap.dev.of_node = child; + break; + } + } + } + if (force_nr) { priv->adap.nr = force_nr; ret = i2c_add_numbered_adapter(&priv->adap); @@ -142,6 +163,8 @@ struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent, dev_info(&parent->dev, "Added multiplexed i2c bus %d\n", i2c_adapter_id(&priv->adap)); + of_i2c_register_devices(&priv->adap); + return &priv->adap; } EXPORT_SYMBOL_GPL(i2c_add_mux_adapter); |