gpio: cdev: prepare gpio_desc_to_lineinfo() for being called from atomic

In order to prepare gpio_desc_to_lineinfo() to being called from atomic
context, add a new argument - bool atomic - which, if set, indicates
that no sleeping functions must be called (currently: only
pinctrl_gpio_can_use_line()).

Reviewed-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20241018-gpio-notify-in-kernel-events-v5-4-c79135e58a1c@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/gpiolib-cdev.c

@@ -2235,7 +2235,7 @@ static void gpio_v2_line_info_changed_to_v1(
 #endif /* CONFIG_GPIO_CDEV_V1 */
 
 static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
-				  struct gpio_v2_line_info *info)
+				  struct gpio_v2_line_info *info, bool atomic)
 {
 	u32 debounce_period_us;
 	unsigned long dflags;
@@ -2277,9 +2277,12 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 	    test_bit(FLAG_USED_AS_IRQ, &dflags) ||
 	    test_bit(FLAG_EXPORT, &dflags) ||
 	    test_bit(FLAG_SYSFS, &dflags) ||
-	    !gpiochip_line_is_valid(guard.gc, info->offset) ||
-	    !pinctrl_gpio_can_use_line(guard.gc, info->offset))
+	    !gpiochip_line_is_valid(guard.gc, info->offset)) {
 		info->flags |= GPIO_V2_LINE_FLAG_USED;
+	} else if (!atomic) {
+		if (!pinctrl_gpio_can_use_line(guard.gc, info->offset))
+			info->flags |= GPIO_V2_LINE_FLAG_USED;
+	}
 
 	if (test_bit(FLAG_IS_OUT, &dflags))
 		info->flags |= GPIO_V2_LINE_FLAG_OUTPUT;
@@ -2385,7 +2388,7 @@ static int lineinfo_get_v1(struct gpio_chardev_data *cdev, void __user *ip,
 			return -EBUSY;
 	}
 
-	gpio_desc_to_lineinfo(desc, &lineinfo_v2);
+	gpio_desc_to_lineinfo(desc, &lineinfo_v2, false);
 	gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);
 
 	if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
@@ -2422,7 +2425,7 @@ static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip,
 		if (test_and_set_bit(lineinfo.offset, cdev->watched_lines))
 			return -EBUSY;
 	}
-	gpio_desc_to_lineinfo(desc, &lineinfo);
+	gpio_desc_to_lineinfo(desc, &lineinfo, false);
 
 	if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
 		if (watch)
@@ -2514,7 +2517,7 @@ static int lineinfo_changed_notify(struct notifier_block *nb,
 	memset(&chg, 0, sizeof(chg));
 	chg.event_type = action;
 	chg.timestamp_ns = ktime_get_ns();
-	gpio_desc_to_lineinfo(desc, &chg.info);
+	gpio_desc_to_lineinfo(desc, &chg.info, false);
 
 	ret = kfifo_in_spinlocked(&cdev->events, &chg, 1, &cdev->wait.lock);
 	if (ret)