regulator: gpio: Add input_supply support in gpio_regulator_config

This is simillar as fixed-regulator.
Used to extract regulator parent from the device tree.

Without that property used, the parent regulator can be shut down (if not an always on).
Thus leading to inappropriate behavior:
On am62-SP-SK this fix is required to avoid tps65219 ldo1 (SDMMC rail) to be shut down after boot completion.
Signed-off-by: Jerome Neanne <jneanne@baylibre.com>
Link: https://lore.kernel.org/r/20220929132526.29427-2-jneanne@baylibre.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/gpio-regulator.c

@@ -220,6 +220,9 @@ of_get_gpio_regulator_config(struct device *dev, struct device_node *np,
 				 regtype);
 	}
 
+	if (of_find_property(np, "vin-supply", NULL))
+		config->input_supply = "vin";
+
 	return config;
 }
 
@@ -259,6 +262,18 @@ static int gpio_regulator_probe(struct platform_device *pdev)
 
 	drvdata->gpiods = devm_kzalloc(dev, sizeof(struct gpio_desc *),
 				       GFP_KERNEL);
+
+	if (config->input_supply) {
+		drvdata->desc.supply_name = devm_kstrdup(&pdev->dev,
+							 config->input_supply,
+							 GFP_KERNEL);
+		if (!drvdata->desc.supply_name) {
+			dev_err(&pdev->dev,
+				"Failed to allocate input supply\n");
+			return -ENOMEM;
+		}
+	}
+
 	if (!drvdata->gpiods)
 		return -ENOMEM;
 	for (i = 0; i < config->ngpios; i++) {

include/linux/regulator/gpio-regulator.h

@@ -42,6 +42,7 @@ struct gpio_regulator_state {
 /**
  * struct gpio_regulator_config - config structure
  * @supply_name:	Name of the regulator supply
+ * @input_supply:	Name of the input regulator supply
  * @enabled_at_boot:	Whether regulator has been enabled at
  *			boot or not. 1 = Yes, 0 = No
  *			This is used to keep the regulator at
@@ -62,6 +63,7 @@ struct gpio_regulator_state {
  */
 struct gpio_regulator_config {
 	const char *supply_name;
+	const char *input_supply;
 
 	unsigned enabled_at_boot:1;
 	unsigned startup_delay;