[PATCH 1/2] i2c: mux: add device tree support

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

From: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

* Define core portions of the DT binding for I2C bus muxes.
* Enhance i2c_add_mux_adapter():
** Add parameters required for DT support. Update all callers.
** Set the appropriate adap->dev.of_node for the child bus.
** Call of_i2c_register_devices() for the child bus.

Signed-off-by: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
Note: This series depends on the 3 patches I just sent that affect
of_find_i2c_device_by_node and implement of_find_i2c_adapter_by_node.
It might be useful to put this patch (and the others I sent) in
a separate tree so it can be merged into any SoC trees that wish to use
this new feature.

 Documentation/devicetree/bindings/i2c/i2cmux.txt |   45 ++++++++++++++++++++++
 drivers/i2c/i2c-mux.c                            |   23 +++++++++++-
 drivers/i2c/muxes/gpio-i2cmux.c                  |    5 +-
 drivers/i2c/muxes/pca9541.c                      |    4 +-
 drivers/i2c/muxes/pca954x.c                      |    4 +-
 include/linux/i2c-mux.h                          |    4 +-
 6 files changed, 77 insertions(+), 8 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2cmux.txt

diff --git a/Documentation/devicetree/bindings/i2c/i2cmux.txt b/Documentation/devicetree/bindings/i2c/i2cmux.txt
new file mode 100644
index 0000000..1e4e2bc
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2cmux.txt
@@ -0,0 +1,45 @@
+Common I2C mux bindings
+
+An I2C mux is a device that connects a master I2C bus to one of a number of
+child I2C busses, under programmatic control.
+
+Each I2C mux may define the set of child busses it supports in a different
+way. Some devices may have a hard-coded set of child ports, whereas others may
+support a varying set of child busses (especially when the bus mux is
+implemented using GPIOs or pin muxing). Any bindings required to represent
+this are the domain of the individual mux device.
+
+For each child bus, there shall be a node within the I2C mux's own node for
+that bus. This node will contain all the I2C devices on that bus, just like
+any other I2C bus. Each child bus shall be identified by some name. The set
+of child bus names is defined by the individual I2C mux's bindings. Bus names
+are used to construct the name of the bus's child node using the format
+i2c-bus-%s. Each child bus node needs the usual #address-cells and #size-cells
+properties.
+
+Example:
+
+	i2cmux {
+		// properties here omitted from the example.
+
+		i2c-bus-0 {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			eeprom {
+				compatible = "eeprom";
+				reg = <0x50>;
+			};
+		};
+
+		i2c-bus-1 {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			eeprom {
+				compatible = "eeprom";
+				reg = <0x50>;
+			};
+		};
+	};
+
diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index d7a4833..8adeeec 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -24,6 +24,7 @@
 #include <linux/slab.h>
 #include <linux/i2c.h>
 #include <linux/i2c-mux.h>
+#include <linux/of_i2c.h>
 
 /* multiplexer per channel data */
 struct i2c_mux_priv {
@@ -86,8 +87,10 @@ static u32 i2c_mux_functionality(struct i2c_adapter *adap)
 	return parent->algo->functionality(parent);
 }
 
-struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
+struct i2c_adapter *i2c_add_mux_adapter(struct device *dev,
+				struct i2c_adapter *parent,
 				void *mux_dev, u32 force_nr, u32 chan_id,
+				const char *chan_name,
 				int (*select) (struct i2c_adapter *,
 					       void *, u32),
 				int (*deselect) (struct i2c_adapter *,
@@ -124,6 +127,22 @@ struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
 	priv->adap.algo_data = priv;
 	priv->adap.dev.parent = &parent->dev;
 
+	if (dev->of_node) {
+		const char *name;
+
+		if (chan_name)
+			name = kasprintf(GFP_KERNEL, "i2c-bus-%s",
+					     chan_name);
+		else
+			name = kasprintf(GFP_KERNEL, "i2c-bus-%d",
+					     chan_id);
+
+		priv->adap.dev.of_node = of_find_node_by_name(dev->of_node,
+							      name);
+
+		kfree(name);
+	}
+
 	if (force_nr) {
 		priv->adap.nr = force_nr;
 		ret = i2c_add_numbered_adapter(&priv->adap);
@@ -141,6 +160,8 @@ 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);
diff --git a/drivers/i2c/muxes/gpio-i2cmux.c b/drivers/i2c/muxes/gpio-i2cmux.c
index e5fa695..7284c70 100644
--- a/drivers/i2c/muxes/gpio-i2cmux.c
+++ b/drivers/i2c/muxes/gpio-i2cmux.c
@@ -105,8 +105,9 @@ static int __devinit gpiomux_probe(struct platform_device *pdev)
 	for (i = 0; i < pdata->n_values; i++) {
 		u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
 
-		mux->adap[i] = i2c_add_mux_adapter(parent, mux, nr, i,
-						   gpiomux_select, deselect);
+		mux->adap[i] = i2c_add_mux_adapter(&pdev->dev, parent, mux, nr,
+						   i, NULL, gpiomux_select,
+						   deselect);
 		if (!mux->adap[i]) {
 			ret = -ENODEV;
 			dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
diff --git a/drivers/i2c/muxes/pca9541.c b/drivers/i2c/muxes/pca9541.c
index e0df9b6..e1777fb 100644
--- a/drivers/i2c/muxes/pca9541.c
+++ b/drivers/i2c/muxes/pca9541.c
@@ -353,8 +353,8 @@ static int pca9541_probe(struct i2c_client *client,
 	force = 0;
 	if (pdata)
 		force = pdata->modes[0].adap_id;
-	data->mux_adap = i2c_add_mux_adapter(adap, client, force, 0,
-					     pca9541_select_chan,
+	data->mux_adap = i2c_add_mux_adapter(&client->dev, adap, client, force,
+					     0, NULL, pca9541_select_chan,
 					     pca9541_release_chan);
 
 	if (data->mux_adap == NULL) {
diff --git a/drivers/i2c/muxes/pca954x.c b/drivers/i2c/muxes/pca954x.c
index 0e37ef2..736a803 100644
--- a/drivers/i2c/muxes/pca954x.c
+++ b/drivers/i2c/muxes/pca954x.c
@@ -226,8 +226,8 @@ static int pca954x_probe(struct i2c_client *client,
 		}
 
 		data->virt_adaps[num] =
-			i2c_add_mux_adapter(adap, client,
-				force, num, pca954x_select_chan,
+			i2c_add_mux_adapter(&client->dev, adap, client,
+				force, num, NULL, pca954x_select_chan,
 				(pdata && pdata->modes[num].deselect_on_exit)
 					? pca954x_deselect_mux : NULL);
 
diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
index 747f0cd..43fb11a 100644
--- a/include/linux/i2c-mux.h
+++ b/include/linux/i2c-mux.h
@@ -33,8 +33,10 @@
  * and deselect callback functions to perform hardware-specific
  * mux control.
  */
-struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
+struct i2c_adapter *i2c_add_mux_adapter(struct device *dev,
+				struct i2c_adapter *parent,
 				void *mux_dev, u32 force_nr, u32 chan_id,
+				const char *chan_name,
 				int (*select) (struct i2c_adapter *,
 					       void *mux_dev, u32 chan_id),
 				int (*deselect) (struct i2c_adapter *,
-- 
1.7.0.4