gpio: Ensure struct gpio_chip for gpiochip_setup_dev()

Ensure struct gpio_chip for gpiochip_setup_dev().  This eliminates a few
checks for struct gpio_chip.

Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://patch.msgid.link/20260223061726.82161-5-tzungbi@kernel.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

drivers/gpio/gpiolib-cdev.c

@@ -2733,11 +2733,13 @@ static const struct file_operations gpio_fileops = {
 #endif
 };
 
-int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
+int gpiolib_cdev_register(struct gpio_chip *gc, dev_t devt)
 {
-	struct gpio_chip *gc;
+	struct gpio_device *gdev = gc->gpiodev;
 	int ret;
 
+	lockdep_assert_held(&gdev->srcu);
+
 	cdev_init(&gdev->chrdev, &gpio_fileops);
 	gdev->chrdev.owner = THIS_MODULE;
 	gdev->dev.devt = MKDEV(MAJOR(devt), gdev->id);
@@ -2753,14 +2755,6 @@ int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
 		return ret;
 	}
 
-	guard(srcu)(&gdev->srcu);
-	gc = srcu_dereference(gdev->chip, &gdev->srcu);
-	if (!gc) {
-		cdev_device_del(&gdev->chrdev, &gdev->dev);
-		destroy_workqueue(gdev->line_state_wq);
-		return -ENODEV;
-	}
-
 	gpiochip_dbg(gc, "added GPIO chardev (%d:%d)\n", MAJOR(devt), gdev->id);
 
 	return 0;

drivers/gpio/gpiolib-cdev.h

@@ -7,7 +7,7 @@
 
 struct gpio_device;
 
-int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt);
+int gpiolib_cdev_register(struct gpio_chip *gc, dev_t devt);
 void gpiolib_cdev_unregister(struct gpio_device *gdev);
 
 #endif /* GPIOLIB_CDEV_H */

drivers/gpio/gpiolib-sysfs.c

@@ -983,13 +983,15 @@ void gpiod_unexport(struct gpio_desc *desc)
 }
 EXPORT_SYMBOL_GPL(gpiod_unexport);
 
-int gpiochip_sysfs_register(struct gpio_device *gdev)
+int gpiochip_sysfs_register(struct gpio_chip *gc)
 {
+	struct gpio_device *gdev = gc->gpiodev;
 	struct gpiodev_data *data;
-	struct gpio_chip *chip;
 	struct device *parent;
 	int err;
 
+	lockdep_assert_held(&gdev->srcu);
+
 	/*
 	 * Many systems add gpio chips for SOC support very early,
 	 * before driver model support is available.  In those cases we
@@ -999,18 +1001,12 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
 	if (!class_is_registered(&gpio_class))
 		return 0;
 
-	guard(srcu)(&gdev->srcu);
-
-	chip = srcu_dereference(gdev->chip, &gdev->srcu);
-	if (!chip)
-		return -ENODEV;
-
 	/*
 	 * For sysfs backward compatibility we need to preserve this
 	 * preferred parenting to the gpio_chip parent field, if set.
 	 */
-	if (chip->parent)
+	if (gc->parent)
-		parent = chip->parent;
+		parent = gc->parent;
 	else
 		parent = &gdev->dev;
 
@@ -1029,7 +1025,7 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
 						    MKDEV(0, 0), data,
 						    gpiochip_groups,
 						    GPIOCHIP_NAME "%d",
-						    chip->base);
+						    gc->base);
 	if (IS_ERR(data->cdev_base)) {
 		err = PTR_ERR(data->cdev_base);
 		kfree(data);
@@ -1085,10 +1081,9 @@ void gpiochip_sysfs_unregister(struct gpio_chip *gc)
  */
 static int gpiofind_sysfs_register(struct gpio_chip *gc, const void *data)
 {
-	struct gpio_device *gdev = gc->gpiodev;
 	int ret;
 
-	ret = gpiochip_sysfs_register(gdev);
+	ret = gpiochip_sysfs_register(gc);
 	if (ret)
 		gpiochip_err(gc, "failed to register the sysfs entry: %d\n", ret);
 

drivers/gpio/gpiolib-sysfs.h

@@ -7,12 +7,12 @@ struct gpio_device;
 
 #ifdef CONFIG_GPIO_SYSFS
 
-int gpiochip_sysfs_register(struct gpio_device *gdev);
+int gpiochip_sysfs_register(struct gpio_chip *gc);
 void gpiochip_sysfs_unregister(struct gpio_chip *gc);
 
 #else
 
-static inline int gpiochip_sysfs_register(struct gpio_device *gdev)
+static inline int gpiochip_sysfs_register(struct gpio_chip *gc)
 {
 	return 0;
 }

drivers/gpio/gpiolib.c

@@ -882,14 +882,14 @@ static const struct device_type gpio_dev_type = {
 };
 
 #ifdef CONFIG_GPIO_CDEV
-#define gcdev_register(gdev, devt)	gpiolib_cdev_register((gdev), (devt))
+#define gcdev_register(gc, devt)	gpiolib_cdev_register((gc), (devt))
 #define gcdev_unregister(gdev)		gpiolib_cdev_unregister((gdev))
 #else
 /*
  * gpiolib_cdev_register() indirectly calls device_add(), which is still
  * required even when cdev is not selected.
  */
-#define gcdev_register(gdev, devt)	device_add(&(gdev)->dev)
+#define gcdev_register(gc, devt)	device_add(&(gc)->gpiodev->dev)
 #define gcdev_unregister(gdev)		device_del(&(gdev)->dev)
 #endif
 
@@ -897,8 +897,9 @@ static const struct device_type gpio_dev_type = {
  * An initial reference count has been held in gpiochip_add_data_with_key().
  * The caller should drop the reference via gpio_device_put() on errors.
  */
-static int gpiochip_setup_dev(struct gpio_device *gdev)
+static int gpiochip_setup_dev(struct gpio_chip *gc)
 {
+	struct gpio_device *gdev = gc->gpiodev;
 	struct fwnode_handle *fwnode = dev_fwnode(&gdev->dev);
 	int ret;
 
@@ -911,11 +912,11 @@ static int gpiochip_setup_dev(struct gpio_device *gdev)
 	if (fwnode && !fwnode->dev)
 		fwnode_dev_initialized(fwnode, false);
 
-	ret = gcdev_register(gdev, gpio_devt);
+	ret = gcdev_register(gc, gpio_devt);
 	if (ret)
 		return ret;
 
-	ret = gpiochip_sysfs_register(gdev);
+	ret = gpiochip_sysfs_register(gc);
 	if (ret)
 		goto err_remove_device;
 
@@ -962,13 +963,22 @@ static void machine_gpiochip_add(struct gpio_chip *gc)
 static void gpiochip_setup_devs(void)
 {
 	struct gpio_device *gdev;
+	struct gpio_chip *gc;
 	int ret;
 
 	guard(srcu)(&gpio_devices_srcu);
 
 	list_for_each_entry_srcu(gdev, &gpio_devices, list,
 				 srcu_read_lock_held(&gpio_devices_srcu)) {
-		ret = gpiochip_setup_dev(gdev);
+		guard(srcu)(&gdev->srcu);
+
+		gc = srcu_dereference(gdev->chip, &gdev->srcu);
+		if (!gc) {
+			dev_err(&gdev->dev, "Underlying GPIO chip is gone\n");
+			continue;
+		}
+
+		ret = gpiochip_setup_dev(gc);
 		if (ret) {
 			gpio_device_put(gdev);
 			dev_err(&gdev->dev,
@@ -1226,7 +1236,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	 * (i.e., `gpio_bus_type` is ready).  Otherwise, defer until later.
 	 */
 	if (gpiolib_initialized) {
-		ret = gpiochip_setup_dev(gdev);
+		ret = gpiochip_setup_dev(gc);
 		if (ret)
 			goto err_teardown_shared;
 	}