Add dt_node interface for usege through device-tree

Originally, the driver works only via the old platform-driver interface.
Now it uses also the device tree interface. A possible node is:

	rs232-consumer {
		compatible          = "reg-userspace-consumer";
		regulator-name      = "rs232-consumer";
		regulator-supplies  = "reg_rs232_en";
		reg_rs232_en-supply = <&reg_rs232_en>;
		regulator-boot-on;
	};

Where:
- regulator-name: name of the particular istance, used also to create
  the file descriptor at user-space level;
- regulator0supplies : name of the regulator it uses as interface;
- <regulator-supplies>-supply = variable node name. It is the node of
  the regulator that the particular istance uses;
- regulator-boot-on : (default state: off) used to turn on the regulator
  at boot.

drivers/regulator/userspace-consumer.c

@@ -18,6 +18,7 @@
 #include <linux/regulator/consumer.h>
 #include <linux/regulator/userspace-consumer.h>
 #include <linux/slab.h>
+#include <linux/of.h>
 
 struct userspace_consumer_data {
 	const char *name;
@@ -100,6 +101,43 @@ static const struct attribute_group attr_group = {
 	.attrs	= attributes,
 };
 
+
+static struct regulator_userspace_consumer_data *get_pdata_from_dt_node(
+		struct platform_device *pdev)
+{
+	struct regulator_userspace_consumer_data *pdata;
+	struct device_node *np = pdev->dev.of_node;
+	struct property *prop;
+	const char *supply;
+	int num_supplies;
+	int count = 0;
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return ERR_PTR(-ENOMEM);
+
+	pdata->name = of_get_property(np, "regulator-name", NULL);
+	pdata->init_on = of_property_read_bool(np, "regulator-boot-on");
+
+	num_supplies = of_property_count_strings(np, "regulator-supplies");
+	if (num_supplies < 0) {
+		dev_err(&pdev->dev,
+				"could not parse property regulator-supplies\n");
+		return ERR_PTR(-EINVAL);
+	}
+	pdata->num_supplies = num_supplies;
+	pdata->supplies = devm_kzalloc(&pdev->dev, num_supplies *
+			sizeof(*pdata->supplies), GFP_KERNEL);
+	if (!pdata->supplies)
+		return ERR_PTR(-ENOMEM);
+
+	of_property_for_each_string(np, "regulator-supplies", prop, supply)
+		pdata->supplies[count++].supply = supply;
+
+	return pdata;
+}
+
+
 static int regulator_userspace_consumer_probe(struct platform_device *pdev)
 {
 	struct regulator_userspace_consumer_data *pdata;
@@ -107,6 +145,11 @@ static int regulator_userspace_consumer_probe(struct platform_device *pdev)
 	int ret;
 
 	pdata = dev_get_platdata(&pdev->dev);
+	if (!pdata && pdev->dev.of_node) {
+		pdata = get_pdata_from_dt_node(pdev);
+		if (IS_ERR(pdata))
+			return PTR_ERR(pdata);
+	}
 	if (!pdata)
 		return -EINVAL;
 
@@ -166,10 +209,18 @@ static int regulator_userspace_consumer_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct of_device_id regulator_userspace_consumer_of_match[] = {
+	{ .compatible = "reg-userspace-consumer", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, regulator_userspace_consumer_of_match);
+
+
 static struct platform_driver regulator_userspace_consumer_driver = {
 	.probe		= regulator_userspace_consumer_probe,
 	.remove		= regulator_userspace_consumer_remove,
 	.driver		= {
+		.of_match_table = regulator_userspace_consumer_of_match,
 		.name		= "reg-userspace-consumer",
 	},
 };