tps6105x: add optional devicetree support

This driver currently requires platform data to specify the
operational mode and regulator init data (in case of regulator
mode).

Optionally specify the operational mode by looking at the name
of the devicetree child node.

Example: put chip in regulator mode:

i2c0 {
	tps61052@33 {
		compatible = "ti,tps61052";
		reg = <0x33>;

		regulator {
                            regulator-min-microvolt = <5000000>;
                            regulator-max-microvolt = <5000000>;
                            regulator-always-on;
		};
	};
};

Tree: linux-next
Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Link: https://lore.kernel.org/r/20191119154611.29625-2-TheSven73@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/mfd/tps6105x.c

@@ -91,6 +91,32 @@ static int tps6105x_add_device(struct tps6105x *tps6105x,
 			       PLATFORM_DEVID_AUTO, cell, 1, NULL, 0, NULL);
 }
 
+static struct tps6105x_platform_data *tps6105x_parse_dt(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	struct tps6105x_platform_data *pdata;
+	struct device_node *child;
+
+	if (!np)
+		return ERR_PTR(-EINVAL);
+	if (of_get_available_child_count(np) > 1) {
+		dev_err(dev, "cannot support multiple operational modes");
+		return ERR_PTR(-EINVAL);
+	}
+	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return ERR_PTR(-ENOMEM);
+	pdata->mode = TPS6105X_MODE_SHUTDOWN;
+	for_each_available_child_of_node(np, child) {
+		if (child->name && !of_node_cmp(child->name, "regulator"))
+			pdata->mode = TPS6105X_MODE_VOLTAGE;
+		else if (child->name && !of_node_cmp(child->name, "led"))
+			pdata->mode = TPS6105X_MODE_TORCH;
+	}
+
+	return pdata;
+}
+
 static int tps6105x_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
@@ -99,9 +125,11 @@ static int tps6105x_probe(struct i2c_client *client,
 	int ret;
 
 	pdata = dev_get_platdata(&client->dev);
-	if (!pdata) {
-		dev_err(&client->dev, "missing platform data\n");
-		return -ENODEV;
+	if (!pdata)
+		pdata = tps6105x_parse_dt(&client->dev);
+	if (IS_ERR(pdata)) {
+		dev_err(&client->dev, "No platform data or DT found");
+		return PTR_ERR(pdata);
 	}
 
 	tps6105x = devm_kmalloc(&client->dev, sizeof(*tps6105x), GFP_KERNEL);