The kernel currenly has only 2 usb_device_drivers, one generic one, one
that completely replaces the generic one to make USB devices usable over
a network.

Use the newly exported generic driver functions when a driver declares
to want them run, in addition to its own code. This makes it possible to
write drivers that extend the generic USB driver.

Signed-off-by: Bastien Nocera <had...@hadess.net>
---
 drivers/usb/core/driver.c | 36 ++++++++++++++++++++++++++++++------
 include/linux/usb.h       |  1 +
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 2b27d232d7a7..863e380a272b 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -261,10 +261,17 @@ static int usb_probe_device(struct device *dev)
         */
        if (!udriver->supports_autosuspend)
                error = usb_autoresume_device(udev);
+       if (error)
+               return error;
 
-       if (!error)
-               error = udriver->probe(udev);
-       return error;
+       if (udriver->generic_init)
+               error = usb_generic_driver_probe(udev);
+       if (error)
+               return error;
+
+       if (udriver->probe)
+               return udriver->probe(udev);
+       return 0;
 }
 
 /* called from driver core with dev locked */
@@ -273,7 +280,10 @@ static int usb_unbind_device(struct device *dev)
        struct usb_device *udev = to_usb_device(dev);
        struct usb_device_driver *udriver = to_usb_device_driver(dev->driver);
 
-       udriver->disconnect(udev);
+       if (udriver->generic_init)
+               usb_generic_driver_disconnect(udev);
+       if (udriver->disconnect)
+               udriver->disconnect(udev);
        if (!udriver->supports_autosuspend)
                usb_autosuspend_device(udev);
        return 0;
@@ -886,6 +896,14 @@ int usb_register_device_driver(struct usb_device_driver 
*new_udriver,
        if (usb_disabled())
                return -ENODEV;
 
+       if (new_udriver->probe == NULL &&
+           !new_udriver->generic_init) {
+               printk(KERN_ERR "%s: error %d registering device "
+                      "        driver %s, no probe() function\n",
+                      usbcore_name, retval, new_udriver->name);
+               return -EINVAL;
+       }
+
        new_udriver->drvwrap.for_devices = 1;
        new_udriver->drvwrap.driver.name = new_udriver->name;
        new_udriver->drvwrap.driver.bus = &usb_bus_type;
@@ -1149,7 +1167,10 @@ static int usb_suspend_device(struct usb_device *udev, 
pm_message_t msg)
                udev->do_remote_wakeup = 0;
                udriver = &usb_generic_driver;
        }
-       status = udriver->suspend(udev, msg);
+       if (udriver->generic_init)
+               status = usb_generic_driver_suspend (udev, msg);
+       if (status == 0 && udriver->suspend)
+               status = udriver->suspend(udev, msg);
 
  done:
        dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status);
@@ -1181,7 +1202,10 @@ static int usb_resume_device(struct usb_device *udev, 
pm_message_t msg)
                udev->reset_resume = 1;
 
        udriver = to_usb_device_driver(udev->dev.driver);
-       status = udriver->resume(udev, msg);
+       if (udriver->generic_init)
+               status = usb_generic_driver_resume (udev, msg);
+       if (status == 0 && udriver->resume)
+               status = udriver->resume(udev, msg);
 
  done:
        dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status);
diff --git a/include/linux/usb.h b/include/linux/usb.h
index e656e7b4b1e4..fb9ad3511e55 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1242,6 +1242,7 @@ struct usb_device_driver {
        const struct attribute_group **dev_groups;
        struct usbdrv_wrap drvwrap;
        unsigned int supports_autosuspend:1;
+       unsigned int generic_init:1;
 };
 #define        to_usb_device_driver(d) container_of(d, struct 
usb_device_driver, \
                drvwrap.driver)
-- 
2.21.0

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