i2c/of: Automatically populate i2c mux busses from device tree data.

For 'normal' i2c bus drivers, we can call of_i2c_register_devices() and have the device tree framework automatically populate the bus with the devices specified in the device tree. This patch adds a common code to the i2c mux framework to have the mux sub-busses be populated by the of_i2c_register_devices() too. If the mux device has an of_node, we populate the sub-bus' of_node so that the subsequent call to of_i2c_register_devices() will find the corresponding devices. It seemed better to put this logic in i2c_add_mux_adapter() rather than the individual mux drivers, as they will all probably want to do the same thing. Signed-off-by: David Daney <david.daney@cavium.com> Acked-by: Stephen Warren <swarren@wwwdotorg.org> Tested-by: Lars-Peter Clausen <lars@metafoo.de> [wsa: removed superfluous ret-variable and fixed a typo in a comment] Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>

i2c/of: Automatically populate i2c mux busses from device tree data.
For 'normal' i2c bus drivers, we can call of_i2c_register_devices() and have the device tree framework automatically populate the bus with the devices specified in the device tree. This patch adds a common code to the i2c mux framework to have the mux sub-busses be populated by the of_i2c_register_devices() too. If the mux device has an of_node, we populate the sub-bus' of_node so that the subsequent call to of_i2c_register_devices() will find the corresponding devices. It seemed better to put this logic in i2c_add_mux_adapter() rather than the individual mux drivers, as they will all probably want to do the same thing. Signed-off-by: David Daney <david.daney@cavium.com> Acked-by: Stephen Warren <swarren@wwwdotorg.org> Tested-by: Lars-Peter Clausen <lars@metafoo.de> [wsa: removed superfluous ret-variable and fixed a typo in a comment] Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
David Daney · Wolfram Sang
1 parent 5a3ecd5f98
Showing 2 changed files with 83 additions and 0 deletions Side-by-side Diff
Documentation/devicetree/bindings/i2c/mux.txt
drivers/i2c/i2c-mux.c
+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;
+			};
+		};
+	};
@@ -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 @@
 	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", &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);
@@ -141,6 +162,8 @@
  
 	dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
 		 i2c_adapter_id(&priv->adap));
+
+	of_i2c_register_devices(&priv->adap);
  
 	return &priv->adap;
 }
	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
	5	+multiplexer/switch will have one child node for each child
	6	+bus.
	7	+
	8	+Required properties:
	9	+- #address-cells = <1>;
	10	+- #size-cells = <0>;
	11	+
	12	+Required properties for child nodes:
	13	+- #address-cells = <1>;
	14	+- #size-cells = <0>;
	15	+- reg : The sub-bus number.
	16	+
	17	+Optional properties for child nodes:
	18	+- Other properties specific to the multiplexer/switch hardware.
	19	+- Child nodes conforming to i2c bus binding
	20	+
	21	+
	22	+Example :
	23	+
	24	+ /*
	25	+ An NXP pca9548 8 channel I2C multiplexer at address 0x70
	26	+ with two NXP pca8574 GPIO expanders attached, one each to
	27	+ ports 3 and 4.
	28	+ */
	29	+
	30	+ mux@70 {
	31	+ compatible = "nxp,pca9548";
	32	+ reg = <0x70>;
	33	+ #address-cells = <1>;
	34	+ #size-cells = <0>;
	35	+
	36	+ i2c@3 {
	37	+ #address-cells = <1>;
	38	+ #size-cells = <0>;
	39	+ reg = <3>;
	40	+
	41	+ gpio1: gpio@38 {
	42	+ compatible = "nxp,pca8574";
	43	+ reg = <0x38>;
	44	+ #gpio-cells = <2>;
	45	+ gpio-controller;
	46	+ };
	47	+ };
	48	+ i2c@4 {
	49	+ #address-cells = <1>;
	50	+ #size-cells = <0>;
	51	+ reg = <4>;
	52	+
	53	+ gpio2: gpio@38 {
	54	+ compatible = "nxp,pca8574";
	55	+ reg = <0x38>;
	56	+ #gpio-cells = <2>;
	57	+ gpio-controller;
	58	+ };
	59	+ };
	60	+ };
...	...	@@ -24,6 +24,8 @@
24	24	#include <linux/slab.h>
25	25	#include <linux/i2c.h>
26	26	#include <linux/i2c-mux.h>
	27	+#include <linux/of.h>
	28	+#include <linux/of_i2c.h>
27	29
28	30	/* multiplexer per channel data */
29	31	struct i2c_mux_priv {
...	...	@@ -125,6 +127,25 @@
125	127	priv->adap.algo_data = priv;
126	128	priv->adap.dev.parent = &parent->dev;
127	129
	130	+ /*
	131	+ * Try to populate the mux adapter's of_node, expands to
	132	+ * nothing if !CONFIG_OF.
	133	+ */
	134	+ if (mux_dev->of_node) {
	135	+ struct device_node *child;
	136	+ u32 reg;
	137	+
	138	+ for_each_child_of_node(mux_dev->of_node, child) {
	139	+ ret = of_property_read_u32(child, "reg", &reg);
	140	+ if (ret)
	141	+ continue;
	142	+ if (chan_id == reg) {
	143	+ priv->adap.dev.of_node = child;
	144	+ break;
	145	+ }
	146	+ }
	147	+ }
	148	+
128	149	if (force_nr) {
129	150	priv->adap.nr = force_nr;
130	151	ret = i2c_add_numbered_adapter(&priv->adap);
...	...	@@ -141,6 +162,8 @@
141	162
142	163	dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
143	164	i2c_adapter_id(&priv->adap));
	165	+
	166	+ of_i2c_register_devices(&priv->adap);
144	167
145	168	return &priv->adap;
146	169	}