usbcore: add usb_device_driver definition

This patch (as732) adds a usb_device_driver structure, for representing
drivers that manage an entire USB device as opposed to just an
interface.  Support routines like usb_register_device_driver,
usb_deregister_device_driver, usb_probe_device, and usb_unbind_device
are also added.

Unlike an earlier version of this patch, the new code is type-safe.  To
accomplish this, the existing struct driver embedded in struct
usb_driver had to be wrapped in an intermediate wrapper.  This enables
the core to tell at runtime whether a particular struct driver belongs
to a device driver or to an interface driver.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/generic.c

@@ -21,14 +21,12 @@
 #include <linux/usb.h>
 #include "usb.h"
 
-static int generic_probe(struct device *dev)
+static int generic_probe(struct usb_device *udev)
 {
 	return 0;
 }
-static int generic_remove(struct device *dev)
+static void generic_disconnect(struct usb_device *udev)
 {
-	struct usb_device *udev = to_usb_device(dev);
-
 	/* if this is only an unbind, not a physical disconnect, then
 	 * unconfigure the device */
 	if (udev->state == USB_STATE_CONFIGURED)
@@ -37,17 +35,10 @@ static int generic_remove(struct device *dev)
 	/* in case the call failed or the device was suspended */
 	if (udev->state >= USB_STATE_CONFIGURED)
 		usb_disable_device(udev, 0);
-	return 0;
 }
 
-struct device_driver usb_generic_driver = {
-	.owner = THIS_MODULE,
+struct usb_device_driver usb_generic_driver = {
 	.name =	"usb",
-	.bus = &usb_bus_type,
 	.probe = generic_probe,
-	.remove = generic_remove,
+	.disconnect = generic_disconnect,
 };
-
-/* Fun hack to determine if the struct device is a
- * usb device or a usb interface. */
-int usb_generic_driver_data;

drivers/usb/core/usb.c

@@ -123,7 +123,7 @@ static int __find_interface(struct device * dev, void * data)
 	struct usb_interface *intf;
 
 	/* can't look at usb devices, only interfaces */
-	if (dev->driver == &usb_generic_driver)
+	if (is_usb_device(dev))
 		return 0;
 
 	intf = to_usb_interface(dev);
@@ -149,7 +149,8 @@ struct usb_interface *usb_find_interface(struct usb_driver *drv, int minor)
 
 	argb.minor = minor;
 	argb.interface = NULL;
-	driver_for_each_device(&drv->driver, NULL, &argb, __find_interface);
+	driver_for_each_device(&drv->drvwrap.driver, NULL, &argb,
+			__find_interface);
 	return argb.interface;
 }
 
@@ -204,11 +205,13 @@ usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port1)
 	device_initialize(&dev->dev);
 	dev->dev.bus = &usb_bus_type;
 	dev->dev.dma_mask = bus->controller->dma_mask;
-	dev->dev.driver_data = &usb_generic_driver_data;
-	dev->dev.driver = &usb_generic_driver;
+	dev->dev.driver = &usb_generic_driver.drvwrap.driver;
 	dev->dev.release = usb_release_dev;
 	dev->state = USB_STATE_ATTACHED;
 
+	/* This magic assignment distinguishes devices from interfaces */
+	dev->dev.platform_data = &usb_generic_driver;
+
 	INIT_LIST_HEAD(&dev->ep0.urb_list);
 	dev->ep0.desc.bLength = USB_DT_ENDPOINT_SIZE;
 	dev->ep0.desc.bDescriptorType = USB_DT_ENDPOINT;
@@ -838,7 +841,7 @@ static int __init usb_init(void)
 	retval = usb_hub_init();
 	if (retval)
 		goto hub_init_failed;
-	retval = driver_register(&usb_generic_driver);
+	retval = usb_register_device_driver(&usb_generic_driver, THIS_MODULE);
 	if (!retval)
 		goto out;
 
@@ -868,7 +871,7 @@ static void __exit usb_exit(void)
 	if (nousb)
 		return;
 
-	driver_unregister(&usb_generic_driver);
+	usb_deregister_device_driver(&usb_generic_driver);
 	usb_major_cleanup();
 	usbfs_cleanup();
 	usb_deregister(&usbfs_driver);

drivers/usb/core/usb.h

@@ -34,8 +34,24 @@ extern int usb_port_suspend(struct usb_device *dev);
 extern int usb_port_resume(struct usb_device *dev);
 
 extern struct bus_type usb_bus_type;
-extern struct device_driver usb_generic_driver;
-extern int usb_generic_driver_data;
+extern struct usb_device_driver usb_generic_driver;
+
+/* Here's how we tell apart devices and interfaces.  Luckily there's
+ * no such thing as a platform USB device, so we can steal the use
+ * of the platform_data field. */
+
+static inline int is_usb_device(struct device *dev)
+{
+	return dev->platform_data == &usb_generic_driver;
+}
+
+/* Do the same for device drivers and interface drivers. */
+
+static inline int is_usb_device_driver(struct device_driver *drv)
+{
+	return container_of(drv, struct usbdrv_wrap, driver)->
+			for_devices;
+}
 
 /* Interfaces and their "power state" are owned by usbcore */
 

include/linux/usb.h

@@ -540,7 +540,17 @@ struct usb_dynids {
 };
 
 /**
- * struct usb_driver - identifies USB driver to usbcore
+ * struct usbdrv_wrap - wrapper for driver-model structure
+ * @driver: The driver-model core driver structure.
+ * @for_devices: Non-zero for device drivers, 0 for interface drivers.
+ */
+struct usbdrv_wrap {
+	struct device_driver driver;
+	int for_devices;
+};
+
+/**
+ * struct usb_driver - identifies USB interface driver to usbcore
  * @name: The driver name should be unique among USB drivers,
  *	and should normally be the same as the module name.
  * @probe: Called to see if the driver is willing to manage a particular
@@ -567,12 +577,12 @@ struct usb_dynids {
  *	or your driver's probe function will never get called.
  * @dynids: used internally to hold the list of dynamically added device
  *	ids for this driver.
- * @driver: the driver model core driver structure.
+ * @drvwrap: Driver-model core structure wrapper.
  * @no_dynamic_id: if set to 1, the USB core will not allow dynamic ids to be
  *	added to this driver by preventing the sysfs file from being created.
  *
- * USB drivers must provide a name, probe() and disconnect() methods,
- * and an id_table.  Other driver fields are optional.
+ * USB interface drivers must provide a name, probe() and disconnect()
+ * methods, and an id_table.  Other driver fields are optional.
  *
  * The id_table is used in hotplugging.  It holds a set of descriptors,
  * and specialized data may be associated with each entry.  That table
@@ -606,10 +616,40 @@ struct usb_driver {
 	const struct usb_device_id *id_table;
 
 	struct usb_dynids dynids;
-	struct device_driver driver;
+	struct usbdrv_wrap drvwrap;
 	unsigned int no_dynamic_id:1;
 };
-#define	to_usb_driver(d) container_of(d, struct usb_driver, driver)
+#define	to_usb_driver(d) container_of(d, struct usb_driver, drvwrap.driver)
+
+/**
+ * struct usb_device_driver - identifies USB device driver to usbcore
+ * @name: The driver name should be unique among USB drivers,
+ *	and should normally be the same as the module name.
+ * @probe: Called to see if the driver is willing to manage a particular
+ *	device.  If it is, probe returns zero and uses dev_set_drvdata()
+ *	to associate driver-specific data with the device.  If unwilling
+ *	to manage the device, return a negative errno value.
+ * @disconnect: Called when the device is no longer accessible, usually
+ *	because it has been (or is being) disconnected or the driver's
+ *	module is being unloaded.
+ * @suspend: Called when the device is going to be suspended by the system.
+ * @resume: Called when the device is being resumed by the system.
+ * @drvwrap: Driver-model core structure wrapper.
+ *
+ * USB drivers must provide all the fields listed above except drvwrap.
+ */
+struct usb_device_driver {
+	const char *name;
+
+	int (*probe) (struct usb_device *udev);
+	void (*disconnect) (struct usb_device *udev);
+
+	int (*suspend) (struct usb_device *udev, pm_message_t message);
+	int (*resume) (struct usb_device *udev);
+	struct usbdrv_wrap drvwrap;
+};
+#define	to_usb_device_driver(d) container_of(d, struct usb_device_driver, \
+		drvwrap.driver)
 
 extern struct bus_type usb_bus_type;
 
@@ -633,13 +673,17 @@ struct usb_class_driver {
  * use these in module_init()/module_exit()
  * and don't forget MODULE_DEVICE_TABLE(usb, ...)
  */
-int usb_register_driver(struct usb_driver *, struct module *);
+extern int usb_register_driver(struct usb_driver *, struct module *);
 static inline int usb_register(struct usb_driver *driver)
 {
 	return usb_register_driver(driver, THIS_MODULE);
 }
 extern void usb_deregister(struct usb_driver *);
 
+extern int usb_register_device_driver(struct usb_device_driver *,
+			struct module *);
+extern void usb_deregister_device_driver(struct usb_device_driver *);
+
 extern int usb_register_dev(struct usb_interface *intf,
 			    struct usb_class_driver *class_driver);
 extern void usb_deregister_dev(struct usb_interface *intf,