pinctrl: Constify pointers to 'pinctrl_desc'

Pin controller core code only stores the pointer to
'struct pinctrl_desc' and does not modify it anywhere.  The pointer can
be changed to pointer to const which makes the code safer, explicit and
later allows constifying 'pinctrl_desc' allocations in individual
drivers.

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/20250611-pinctrl-const-desc-v2-4-b11c1d650384@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

3 files changed, 12 insertions, 11 deletions

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 9046292d1360..73b78d6eac67 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -2062,7 +2062,7 @@ static int pinctrl_check_ops(struct pinctrl_dev *pctldev)
  * @driver_data: private pin controller data for this pin controller
  */
 static struct pinctrl_dev *
-pinctrl_init_controller(struct pinctrl_desc *pctldesc, struct device *dev,
+pinctrl_init_controller(const struct pinctrl_desc *pctldesc, struct device *dev,
 			void *driver_data)
 {
 	struct pinctrl_dev *pctldev;
@@ -2132,7 +2132,8 @@ out_err:
 	return ERR_PTR(ret);
 }
 
-static void pinctrl_uninit_controller(struct pinctrl_dev *pctldev, struct pinctrl_desc *pctldesc)
+static void pinctrl_uninit_controller(struct pinctrl_dev *pctldev,
+				      const struct pinctrl_desc *pctldesc)
 {
 	pinctrl_free_pindescs(pctldev, pctldesc->pins,
 			      pctldesc->npins);
@@ -2209,7 +2210,7 @@ EXPORT_SYMBOL_GPL(pinctrl_enable);
  * struct pinctrl_dev handle. To avoid issues later on, please use the
  * new pinctrl_register_and_init() below instead.
  */
-struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
+struct pinctrl_dev *pinctrl_register(const struct pinctrl_desc *pctldesc,
 				    struct device *dev, void *driver_data)
 {
 	struct pinctrl_dev *pctldev;
@@ -2239,7 +2240,7 @@ EXPORT_SYMBOL_GPL(pinctrl_register);
  * Note that pinctrl_enable() still needs to be manually called after
  * this once the driver is ready.
  */
-int pinctrl_register_and_init(struct pinctrl_desc *pctldesc,
+int pinctrl_register_and_init(const struct pinctrl_desc *pctldesc,
 			      struct device *dev, void *driver_data,
 			      struct pinctrl_dev **pctldev)
 {
@@ -2330,7 +2331,7 @@ static int devm_pinctrl_dev_match(struct device *dev, void *res, void *data)
  * The pinctrl device will be automatically released when the device is unbound.
  */
 struct pinctrl_dev *devm_pinctrl_register(struct device *dev,
-					  struct pinctrl_desc *pctldesc,
+					  const struct pinctrl_desc *pctldesc,
 					  void *driver_data)
 {
 	struct pinctrl_dev **ptr, *pctldev;
@@ -2364,7 +2365,7 @@ EXPORT_SYMBOL_GPL(devm_pinctrl_register);
  * The pinctrl device will be automatically released when the device is unbound.
  */
 int devm_pinctrl_register_and_init(struct device *dev,
-				   struct pinctrl_desc *pctldesc,
+				   const struct pinctrl_desc *pctldesc,
 				   void *driver_data,
 				   struct pinctrl_dev **pctldev)
 {
diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h
index d6c24978e708..fc513a9cdd4f 100644
--- a/drivers/pinctrl/core.h
+++ b/drivers/pinctrl/core.h
@@ -51,7 +51,7 @@ struct pinctrl_state;
  */
 struct pinctrl_dev {
 	struct list_head node;
-	struct pinctrl_desc *desc;
+	const struct pinctrl_desc *desc;
 	struct radix_tree_root pin_desc_tree;
 #ifdef CONFIG_GENERIC_PINCTRL_GROUPS
 	struct radix_tree_root pin_group_tree;
diff --git a/include/linux/pinctrl/pinctrl.h b/include/linux/pinctrl/pinctrl.h
index 9a8189ffd0f2..d138e1815645 100644
--- a/include/linux/pinctrl/pinctrl.h
+++ b/include/linux/pinctrl/pinctrl.h
@@ -165,25 +165,25 @@ struct pinctrl_desc {
 
 /* External interface to pin controller */
 
-extern int pinctrl_register_and_init(struct pinctrl_desc *pctldesc,
+extern int pinctrl_register_and_init(const struct pinctrl_desc *pctldesc,
 				     struct device *dev, void *driver_data,
 				     struct pinctrl_dev **pctldev);
 extern int pinctrl_enable(struct pinctrl_dev *pctldev);
 
 /* Please use pinctrl_register_and_init() and pinctrl_enable() instead */
-extern struct pinctrl_dev *pinctrl_register(struct pinctrl_desc *pctldesc,
+extern struct pinctrl_dev *pinctrl_register(const struct pinctrl_desc *pctldesc,
 				struct device *dev, void *driver_data);
 
 extern void pinctrl_unregister(struct pinctrl_dev *pctldev);
 
 extern int devm_pinctrl_register_and_init(struct device *dev,
-				struct pinctrl_desc *pctldesc,
+				const struct pinctrl_desc *pctldesc,
 				void *driver_data,
 				struct pinctrl_dev **pctldev);
 
 /* Please use devm_pinctrl_register_and_init() instead */
 extern struct pinctrl_dev *devm_pinctrl_register(struct device *dev,
-				struct pinctrl_desc *pctldesc,
+				const struct pinctrl_desc *pctldesc,
 				void *driver_data);
 
 extern void devm_pinctrl_unregister(struct device *dev,