regulator: fixed: dt: support for input supply

Add support for input supply in DT parsing of node.
The input supply will be provided by the property
"vin-supply" in the regulator node.

Signed-off-by: Laxman Dewangan <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/regulator/fixed-regulator.txt

···
 If this property is missing, the default assumed is Active low.
 - gpio-open-drain: GPIO is open drain type.
   If this property is missing then default assumption is false.
+-vin-supply: Input supply name.
 
 Any property defined as part of the core regulator
 binding, defined in regulator.txt, can also be used.
···
 		enable-active-high;
 		regulator-boot-on;
 		gpio-open-drain;
+		vin-supply = <&parent_reg>;
 	};

drivers/regulator/fixed.c

···
 	if (of_find_property(np, "gpio-open-drain", NULL))
 		config->gpio_is_open_drain = true;
 
+	if (of_find_property(np, "vin-supply", NULL))
+		config->input_supply = "vin";
+
 	return config;
 }
 
···
 
 	drvdata->desc.enable_time = config->startup_delay;
 
+	if (config->input_supply) {
+		drvdata->desc.supply_name = kstrdup(config->input_supply,
+							GFP_KERNEL);
+		if (!drvdata->desc.supply_name) {
+			dev_err(&pdev->dev,
+				"Failed to allocate input supply\n");
+			ret = -ENOMEM;
+			goto err_name;
+		}
+	}
+
 	if (config->microvolts)
 		drvdata->desc.n_voltages = 1;
 
···
 	if (IS_ERR(drvdata->dev)) {
 		ret = PTR_ERR(drvdata->dev);
 		dev_err(&pdev->dev, "Failed to register regulator: %d\n", ret);
-		goto err_name;
+		goto err_input;
 	}
 
 	platform_set_drvdata(pdev, drvdata);
···
 
 	return 0;
 
+err_input:
+	kfree(drvdata->desc.supply_name);
 err_name:
 	kfree(drvdata->desc.name);
 err:
···
 	struct fixed_voltage_data *drvdata = platform_get_drvdata(pdev);
 
 	regulator_unregister(drvdata->dev);
+	kfree(drvdata->desc.supply_name);
 	kfree(drvdata->desc.name);
 
 	return 0;

include/linux/regulator/fixed.h

···
 /**
  * struct fixed_voltage_config - fixed_voltage_config structure
  * @supply_name:	Name of the regulator supply
+ * @input_supply:	Name of the input regulator supply
  * @microvolts:		Output voltage of regulator
  * @gpio:		GPIO to use for enable control
  * 			set to -EINVAL if not used
···
  */
 struct fixed_voltage_config {
 	const char *supply_name;
+	const char *input_supply;
 	int microvolts;
 	int gpio;
 	unsigned startup_delay;