[v3,4/7] drivers: Introduce device lookup variants by device type

diff --git a/drivers/base/core.c b/drivers/base/core.c
index e8f81a667545..3abc32b60c0a 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2867,13 +2867,6 @@  struct device *device_create_with_groups(struct class *class,
 }
 EXPORT_SYMBOL_GPL(device_create_with_groups);
 
-static int __match_devt(struct device *dev, const void *data)
-{
-	const dev_t *devt = data;
-
-	return dev->devt == *devt;
-}
-
 /**
  * device_destroy - removes a device that was created with device_create()
  * @class: pointer to the struct class that this device was registered with
@@ -2886,7 +2879,7 @@  void device_destroy(struct class *class, dev_t devt)
 {
 	struct device *dev;
 
-	dev = class_find_device(class, NULL, &devt, __match_devt);
+	dev = class_find_device_by_devt(class, devt);
 	if (dev) {
 		put_device(dev);
 		device_unregister(dev);
@@ -3374,3 +3367,9 @@  int device_match_fwnode(struct device *dev, const void *fwnode)
 	return dev_fwnode(dev) == fwnode;
 }
 EXPORT_SYMBOL_GPL(device_match_fwnode);
+
+int device_match_devt(struct device *dev, const void *pdevt)
+{
+	return dev->devt == *(dev_t *)pdevt;
+}
+EXPORT_SYMBOL_GPL(device_match_devt);
diff --git a/drivers/hwtracing/intel_th/core.c b/drivers/hwtracing/intel_th/core.c
index 55922896d862..d5c1821b31c6 100644
--- a/drivers/hwtracing/intel_th/core.c
+++ b/drivers/hwtracing/intel_th/core.c
@@ -789,12 +789,6 @@  static int intel_th_populate(struct intel_th *th)
 	return 0;
 }
 
-static int match_devt(struct device *dev, const void *data)
-{
-	dev_t devt = (dev_t)(unsigned long)(void *)data;
-	return dev->devt == devt;
-}
-
 static int intel_th_output_open(struct inode *inode, struct file *file)
 {
 	const struct file_operations *fops;
@@ -802,9 +796,7 @@  static int intel_th_output_open(struct inode *inode, struct file *file)
 	struct device *dev;
 	int err;
 
-	dev = bus_find_device(&intel_th_bus, NULL,
-			      (void *)(unsigned long)inode->i_rdev,
-			      match_devt);
+	dev = bus_find_device_by_devt(&intel_th_bus, inode->i_rdev);
 	if (!dev || !dev->driver)
 		return -ENODEV;
 
diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index f894d1f8a53e..7310b476323c 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -858,13 +858,6 @@  static ssize_t dev_state_show(struct device *device,
 }
 static DEVICE_ATTR_RO(dev_state);
 
-static int match_devt(struct device *dev, const void *data)
-{
-	const dev_t *devt = data;
-
-	return dev->devt == *devt;
-}
-
 /**
  * dev_set_devstate: set to new device state and notify sysfs file.
  *
@@ -880,7 +873,7 @@  void mei_set_devstate(struct mei_device *dev, enum mei_dev_state state)
 
 	dev->dev_state = state;
 
-	clsdev = class_find_device(mei_class, NULL, &dev->cdev.dev, match_devt);
+	clsdev = class_find_device_by_devt(mei_class, dev->cdev.dev);
 	if (clsdev) {
 		sysfs_notify(&clsdev->kobj, NULL, "dev_state");
 		put_device(clsdev);
diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c
index 38a5a47b8c9c..150f6236c9bb 100644
--- a/drivers/s390/crypto/zcrypt_api.c
+++ b/drivers/s390/crypto/zcrypt_api.c
@@ -133,12 +133,6 @@  struct zcdn_device {
 static int zcdn_create(const char *name);
 static int zcdn_destroy(const char *name);
 
-/* helper function, matches the devt value for find_zcdndev_by_devt() */
-static int __match_zcdn_devt(struct device *dev, const void *data)
-{
-	return dev->devt == *((dev_t *) data);
-}
-
 /*
  * Find zcdn device by name.
  * Returns reference to the zcdn device which needs to be released
@@ -158,10 +152,7 @@  static inline struct zcdn_device *find_zcdndev_by_name(const char *name)
  */
 static inline struct zcdn_device *find_zcdndev_by_devt(dev_t devt)
 {
-	struct device *dev =
-		class_find_device(zcrypt_class, NULL,
-				  (void *) &devt,
-				  __match_zcdn_devt);
+	struct device *dev = class_find_device_by_devt(zcrypt_class, devt);
 
 	return dev ? to_zcdn_dev(dev) : NULL;
 }
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 566728fbaf3c..802c1210558f 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2952,17 +2952,11 @@  void do_SAK(struct tty_struct *tty)
 
 EXPORT_SYMBOL(do_SAK);
 
-static int dev_match_devt(struct device *dev, const void *data)
-{
-	const dev_t *devt = data;
-	return dev->devt == *devt;
-}
-
 /* Must put_device() after it's unused! */
 static struct device *tty_get_device(struct tty_struct *tty)
 {
 	dev_t devt = tty_devnum(tty);
-	return class_find_device(tty_class, NULL, &devt, dev_match_devt);
+	return class_find_device_by_devt(tty_class, devt);
 }
 
 
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index b265ab5405f9..60268aee93a8 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -942,17 +942,11 @@  static int parse_usbdevfs_streams(struct usb_dev_state *ps,
 	return ret;
 }
 
-static int match_devt(struct device *dev, const void *data)
-{
-	return dev->devt == (dev_t)(unsigned long)(void *)data;
-}
-
 static struct usb_device *usbdev_lookup_by_devt(dev_t devt)
 {
 	struct device *dev;
 
-	dev = bus_find_device(&usb_bus_type, NULL,
-			      (void *) (unsigned long) devt, match_devt);
+	dev = bus_find_device_by_devt(&usb_bus_type, devt);
 	if (!dev)
 		return NULL;
 	return to_usb_device(dev);
diff --git a/include/linux/device.h b/include/linux/device.h
index 7133fc1c285d..93b2f55ef44e 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -167,6 +167,7 @@  void subsys_dev_iter_exit(struct subsys_dev_iter *iter);
 int device_match_name(struct device *dev, const void *name);
 int device_match_of_node(struct device *dev, const void *np);
 int device_match_fwnode(struct device *dev, const void *fwnode);
+int device_match_devt(struct device *dev, const void *pdevt);
 
 int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data,
 		     int (*fn)(struct device *dev, void *data));
@@ -211,6 +212,18 @@  bus_find_device_by_fwnode(struct bus_type *bus, const struct fwnode_handle *fwno
 	return bus_find_device(bus, NULL, fwnode, device_match_fwnode);
 }
 
+/**
+ * bus_find_device_by_devt : device iterator for locating a particular device
+ * matching the device type.
+ * @bus: bus type
+ * @devt: device type of the device to match.
+ */
+static inline struct device *bus_find_device_by_devt(struct bus_type *bus,
+						     dev_t devt)
+{
+	return bus_find_device(bus, NULL, &devt, device_match_devt);
+}
+
 struct device *subsys_find_device_by_id(struct bus_type *bus, unsigned int id,
 					struct device *hint);
 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
@@ -417,6 +430,18 @@  driver_find_device_by_fwnode(struct device_driver *drv,
 	return driver_find_device(drv, NULL, fwnode, device_match_fwnode);
 }
 
+/**
+ * driver_find_device_by_devt- device iterator for locating a particular device
+ * by devt.
+ * @driver: the driver we're iterating
+ * @devt: devt pointer to match.
+ */
+static inline struct device *driver_find_device_by_devt(struct device_driver *drv,
+							dev_t devt)
+{
+	return driver_find_device(drv, NULL, &devt, device_match_devt);
+}
+
 void driver_deferred_probe_add(struct device *dev);
 int driver_deferred_probe_check_state(struct device *dev);
 int driver_deferred_probe_check_state_continue(struct device *dev);
@@ -583,6 +608,18 @@  class_find_device_by_fwnode(struct class *class,
 	return class_find_device(class, NULL, fwnode, device_match_fwnode);
 }
 
+/**
+ * class_find_device_by_devt : device iterator for locating a particular device
+ * matching the device type.
+ * @class: class type
+ * @devt: device type of the device to match.
+ */
+static inline struct device *class_find_device_by_devt(struct class *class,
+						       dev_t devt)
+{
+	return class_find_device(class, NULL, &devt, device_match_devt);
+}
+
 struct class_attribute {
 	struct attribute attr;
 	ssize_t (*show)(struct class *class, struct class_attribute *attr,