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.com
Signed-off-by: Mark Brown <broonie@kernel.org>
 
                                 regtype);
        }
 
+       if (of_find_property(np, "vin-supply", NULL))
+               config->input_supply = "vin";
+
        return config;
 }
 
 
        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++) {
 
 /**
  * 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
  */
 struct gpio_regulator_config {
        const char *supply_name;
+       const char *input_supply;
 
        unsigned enabled_at_boot:1;
        unsigned startup_delay;