mfd: as3711: Add OF support

Add Flat Device Tree support to the AS3711 MFD driver. This patch just
allows to bind the driver to I2C devices, instantiated from the DT.
DT support for AS3711 cell drivers will be added in separate drivers.

Signed-off-by: Guennadi Liakhovetski <[e-mail]>
Reviwed-by: Mark Brown <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>

Documentation/devicetree/bindings/mfd/as3711.txt

···
+AS3711 is an I2C PMIC from Austria MicroSystems with multiple DCDC and LDO power
+supplies, a battery charger and an RTC. So far only bindings for the two stepup
+DCDC converters are defined. Other DCDC and LDO supplies are configured, using
+standard regulator properties, they must belong to a sub-node, called
+"regulators" and be called "sd1" to "sd4" and "ldo1" to "ldo8." Stepup converter
+configuration should be placed in a subnode, called "backlight."
+
+Compulsory properties:
+- compatible		: must be "ams,as3711"
+- reg			: specifies the I2C address
+
+To use the SU1 converter as a backlight source the following two properties must
+be provided:
+- su1-dev		: framebuffer phandle
+- su1-max-uA		: maximum current
+
+To use the SU2 converter as a backlight source the following two properties must
+be provided:
+- su2-dev		: framebuffer phandle
+- su1-max-uA		: maximum current
+
+Additionally one of these properties must be provided to select the type of
+feedback used:
+- su2-feedback-voltage	: voltage feedback is used
+- su2-feedback-curr1	: CURR1 input used for current feedback
+- su2-feedback-curr2	: CURR2 input used for current feedback
+- su2-feedback-curr3	: CURR3 input used for current feedback
+- su2-feedback-curr-auto: automatic current feedback selection
+
+and one of these to select the over-voltage protection pin
+- su2-fbprot-lx-sd4	: LX_SD4 is used for over-voltage protection
+- su2-fbprot-gpio2	: GPIO2 is used for over-voltage protection
+- su2-fbprot-gpio3	: GPIO3 is used for over-voltage protection
+- su2-fbprot-gpio4	: GPIO4 is used for over-voltage protection
+
+If "su2-feedback-curr-auto" is selected, one or more of the following properties
+have to be specified:
+- su2-auto-curr1	: use CURR1 input for current feedback
+- su2-auto-curr2	: use CURR2 input for current feedback
+- su2-auto-curr3	: use CURR3 input for current feedback
+
+Example:
+
+as3711@40 {
+	compatible = "ams,as3711";
+	reg = <0x40>;
+
+	regulators {
+		sd4 {
+			regulator-name = "1.215V";
+			regulator-min-microvolt = <1215000>;
+			regulator-max-microvolt = <1235000>;
+		};
+		ldo2 {
+			regulator-name = "2.8V CPU";
+			regulator-min-microvolt = <2800000>;
+			regulator-max-microvolt = <2800000>;
+			regulator-always-on;
+			regulator-boot-on;
+		};
+	};
+
+	backlight {
+		compatible = "ams,as3711-bl";
+		su2-dev = <&lcdc>;
+		su2-max-uA = <36000>;
+		su2-feedback-curr-auto;
+		su2-fbprot-gpio4;
+		su2-auto-curr1;
+		su2-auto-curr2;
+		su2-auto-curr3;
+	};
+};

drivers/mfd/as3711.c

···
 	.cache_type = REGCACHE_RBTREE,
 };
 
+#ifdef CONFIG_OF
+static struct of_device_id as3711_of_match[] = {
+	{.compatible = "ams,as3711",},
+	{}
+};
+MODULE_DEVICE_TABLE(of, as3711_of_match);
+#endif
+
 static int as3711_i2c_probe(struct i2c_client *client,
 			    const struct i2c_device_id *id)
 {
 	struct as3711 *as3711;
-	struct as3711_platform_data *pdata = client->dev.platform_data;
+	struct as3711_platform_data *pdata;
 	unsigned int id1, id2;
 	int ret;
 
-	if (!pdata)
-		dev_dbg(&client->dev, "Platform data not found\n");
+	if (!client->dev.of_node) {
+		pdata = client->dev.platform_data;
+		if (!pdata)
+			dev_dbg(&client->dev, "Platform data not found\n");
+	} else {
+		pdata = devm_kzalloc(&client->dev,
+				     sizeof(*pdata), GFP_KERNEL);
+		if (!pdata) {
+			dev_err(&client->dev, "Failed to allocate pdata\n");
+			return -ENOMEM;
+		}
+	}
 
 	as3711 = devm_kzalloc(&client->dev, sizeof(struct as3711), GFP_KERNEL);
 	if (!as3711) {
···
 	.driver = {
 		   .name = "as3711",
 		   .owner = THIS_MODULE,
-		   },
+		   .of_match_table = of_match_ptr(as3711_of_match),
+	},
 	.probe = as3711_i2c_probe,
 	.remove = as3711_i2c_remove,
 	.id_table = as3711_i2c_id,