gpio: don't compare raw GPIO descriptor pointers

Merge series from Bartosz Golaszewski <brgl@bgdev.pl>:

Handling of shared GPIOs in the kernel needs some improvements. Let's
start with a simple change of not comparing GPIO descriptor pointers
directly as there's nothing that guarantees that the same physical pin
will always be represented by a single GPIO descriptor obtained by
calling gpiod_get().

Author: broonie

drivers/gpio/gpiolib.c

@@ -265,6 +265,20 @@ struct gpio_device *gpiod_to_gpio_device(struct gpio_desc *desc)
 }
 EXPORT_SYMBOL_GPL(gpiod_to_gpio_device);
 
+/**
+ * gpiod_is_equal() - Check if two GPIO descriptors refer to the same pin.
+ * @desc: Descriptor to compare.
+ * @other: The second descriptor to compare against.
+ *
+ * Returns:
+ * True if the descriptors refer to the same physical pin. False otherwise.
+ */
+bool gpiod_is_equal(struct gpio_desc *desc, struct gpio_desc *other)
+{
+	return desc == other;
+}
+EXPORT_SYMBOL_GPL(gpiod_is_equal);
+
 /**
  * gpio_device_get_base() - Get the base GPIO number allocated by this device
  * @gdev: GPIO device

drivers/regulator/core.c

@@ -2617,7 +2617,7 @@ static int regulator_ena_gpio_request(struct regulator_dev *rdev,
 	mutex_lock(&regulator_list_mutex);
 
 	list_for_each_entry(pin, &regulator_ena_gpio_list, list) {
-		if (pin->gpiod == gpiod) {
+		if (gpiod_is_equal(pin->gpiod, gpiod)) {
 			rdev_dbg(rdev, "GPIO is already used\n");
 			goto update_ena_gpio_to_rdev;
 		}

include/linux/gpio/consumer.h

@@ -180,6 +180,8 @@ struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
 					      enum gpiod_flags flags,
 					      const char *label);
 
+bool gpiod_is_equal(struct gpio_desc *desc, struct gpio_desc *other);
+
 #else /* CONFIG_GPIOLIB */
 
 #include <linux/bug.h>
@@ -547,6 +549,13 @@ struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
 	return ERR_PTR(-ENOSYS);
 }
 
+static inline bool
+gpiod_is_equal(struct gpio_desc *desc, struct gpio_desc *other)
+{
+	WARN_ON(desc || other);
+	return false;
+}
+
 #endif /* CONFIG_GPIOLIB */
 
 #if IS_ENABLED(CONFIG_GPIOLIB) && IS_ENABLED(CONFIG_HTE)