pinctrl: core: create nolock version of pinctrl_find_gpio_range_from_pin

pinctrl_find_gpio_range_from_pin takes the pctldev->mutex but so
does pinconf_pins_show and this will cause a deadlock if
pinctrl_find_gpio_range_from_pin is used in .pin_config_get
callback.

Create a nolock version of pinctrl_find_gpio_range_from_pin to
allow pin to gpio lookup to be used from pinconf_pins_show.
Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/core.c

@@ -481,18 +481,12 @@ int pinctrl_get_group_pins(struct pinctrl_dev *pctldev, const char *pin_group,
 }
 EXPORT_SYMBOL_GPL(pinctrl_get_group_pins);
 
-/**
- * pinctrl_find_gpio_range_from_pin() - locate the GPIO range for a pin
- * @pctldev: the pin controller device to look in
- * @pin: a controller-local number to find the range for
- */
 struct pinctrl_gpio_range *
-pinctrl_find_gpio_range_from_pin(struct pinctrl_dev *pctldev,
+pinctrl_find_gpio_range_from_pin_nolock(struct pinctrl_dev *pctldev,
 					unsigned int pin)
 {
 	struct pinctrl_gpio_range *range;
 
-	mutex_lock(&pctldev->mutex);
 	/* Loop over the ranges */
 	list_for_each_entry(range, &pctldev->gpio_ranges, node) {
 		/* Check if we're in the valid range */
@@ -500,15 +494,32 @@ pinctrl_find_gpio_range_from_pin(struct pinctrl_dev *pctldev,
 			int a;
 			for (a = 0; a < range->npins; a++) {
 				if (range->pins[a] == pin)
-					goto out;
+					return range;
 			}
 		} else if (pin >= range->pin_base &&
 			   pin < range->pin_base + range->npins)
-			goto out;
+			return range;
 	}
-	range = NULL;
-out:
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(pinctrl_find_gpio_range_from_pin_nolock);
+
+/**
+ * pinctrl_find_gpio_range_from_pin() - locate the GPIO range for a pin
+ * @pctldev: the pin controller device to look in
+ * @pin: a controller-local number to find the range for
+ */
+struct pinctrl_gpio_range *
+pinctrl_find_gpio_range_from_pin(struct pinctrl_dev *pctldev,
+				 unsigned int pin)
+{
+	struct pinctrl_gpio_range *range;
+
+	mutex_lock(&pctldev->mutex);
+	range = pinctrl_find_gpio_range_from_pin_nolock(pctldev, pin);
 	mutex_unlock(&pctldev->mutex);
+
 	return range;
 }
 EXPORT_SYMBOL_GPL(pinctrl_find_gpio_range_from_pin);

drivers/pinctrl/core.h

@@ -182,6 +182,10 @@ static inline struct pin_desc *pin_desc_get(struct pinctrl_dev *pctldev,
 	return radix_tree_lookup(&pctldev->pin_desc_tree, pin);
 }
 
+extern struct pinctrl_gpio_range *
+pinctrl_find_gpio_range_from_pin_nolock(struct pinctrl_dev *pctldev,
+					unsigned int pin);
+
 int pinctrl_register_map(struct pinctrl_map const *maps, unsigned num_maps,
 			 bool dup);
 void pinctrl_unregister_map(struct pinctrl_map const *map);