gpio: add the can_sleep flag to struct gpio_device

Duplicating the can_sleep value in GPIO device will allow us to not
needlessly dereference the chip pointer in several places and reduce the
number of SRCU read-only critical sections.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/gpio/gpiolib.c

@@ -901,6 +901,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	}
 
 	gdev->ngpio = gc->ngpio;
+	gdev->can_sleep = gc->can_sleep;
 
 	scoped_guard(mutex, &gpio_devices_lock) {
 		/*
@@ -3072,7 +3073,7 @@ int gpiod_get_raw_value(const struct gpio_desc *desc)
 {
 	VALIDATE_DESC(desc);
 	/* Should be using gpiod_get_raw_value_cansleep() */
-	WARN_ON(desc->gdev->chip->can_sleep);
+	WARN_ON(desc->gdev->can_sleep);
 	return gpiod_get_raw_value_commit(desc);
 }
 EXPORT_SYMBOL_GPL(gpiod_get_raw_value);
@@ -3093,7 +3094,7 @@ int gpiod_get_value(const struct gpio_desc *desc)
 
 	VALIDATE_DESC(desc);
 	/* Should be using gpiod_get_value_cansleep() */
-	WARN_ON(desc->gdev->chip->can_sleep);
+	WARN_ON(desc->gdev->can_sleep);
 
 	value = gpiod_get_raw_value_commit(desc);
 	if (value < 0)
@@ -3366,7 +3367,7 @@ void gpiod_set_raw_value(struct gpio_desc *desc, int value)
 {
 	VALIDATE_DESC_VOID(desc);
 	/* Should be using gpiod_set_raw_value_cansleep() */
-	WARN_ON(desc->gdev->chip->can_sleep);
+	WARN_ON(desc->gdev->can_sleep);
 	gpiod_set_raw_value_commit(desc, value);
 }
 EXPORT_SYMBOL_GPL(gpiod_set_raw_value);
@@ -3407,7 +3408,7 @@ void gpiod_set_value(struct gpio_desc *desc, int value)
 {
 	VALIDATE_DESC_VOID(desc);
 	/* Should be using gpiod_set_value_cansleep() */
-	WARN_ON(desc->gdev->chip->can_sleep);
+	WARN_ON(desc->gdev->can_sleep);
 	gpiod_set_value_nocheck(desc, value);
 }
 EXPORT_SYMBOL_GPL(gpiod_set_value);
@@ -3471,7 +3472,7 @@ EXPORT_SYMBOL_GPL(gpiod_set_array_value);
 int gpiod_cansleep(const struct gpio_desc *desc)
 {
 	VALIDATE_DESC(desc);
-	return desc->gdev->chip->can_sleep;
+	return desc->gdev->can_sleep;
 }
 EXPORT_SYMBOL_GPL(gpiod_cansleep);
 

drivers/gpio/gpiolib.h

@@ -34,6 +34,8 @@
  * @descs: array of ngpio descriptors.
  * @ngpio: the number of GPIO lines on this GPIO device, equal to the size
  * of the @descs array.
+ * @can_sleep: indicate whether the GPIO chip driver's callbacks can sleep
+ * implying that they cannot be used from atomic context
  * @base: GPIO base in the DEPRECATED global Linux GPIO numberspace, assigned
  * at device creation time.
  * @label: a descriptive name for the GPIO device, such as the part number
@@ -64,6 +66,7 @@ struct gpio_device {
 	struct gpio_desc	*descs;
 	int			base;
 	u16			ngpio;
+	bool			can_sleep;
 	const char		*label;
 	void			*data;
 	struct list_head        list;