USB: Make it possible to "subclass" usb_device_driver

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.

Note that this patch is not enough for another driver to automatically
get selected.

Signed-off-by: Bastien Nocera <hadess@hadess.net>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20191016093933.693-3-hadess@hadess.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 2b27d232d7a75f29af95867ab710fcbb5b8160a9..d3787d0849378b6b42c3f752f33b3fa5f6ac2bdd 100644 (file)
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -261,9 +261,16 @@ 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);
+       if (udriver->generic_subclass)
+               error = usb_generic_driver_probe(udev);
+       if (error)
+               return error;
+
+       error = udriver->probe(udev);
+       /* TODO: fallback to generic driver in case of error */
        return error;
 }
 
@@ -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->disconnect)
+               udriver->disconnect(udev);
+       if (udriver->generic_subclass)
+               usb_generic_driver_disconnect(udev);
        if (!udriver->supports_autosuspend)
                usb_autosuspend_device(udev);
        return 0;
@@ -1149,7 +1159,10 @@ 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->suspend)
+               status = udriver->suspend(udev, msg);
+       if (status == 0 && udriver->generic_subclass)
+               status = usb_generic_driver_suspend(udev, msg);
 
  done:
        dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status);
@@ -1181,7 +1194,10 @@ 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_subclass)
+               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 e656e7b4b1e44cea5047477cf238c066559af92d..94bd3b48a485c4724e017811faccd7627a130525 100644 (file)
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1228,6 +1228,9 @@ struct usb_driver {
  * @drvwrap: Driver-model core structure wrapper.
  * @supports_autosuspend: if set to 0, the USB core will not allow autosuspend
  *     for devices bound to this driver.
+ * @generic_subclass: if set to 1, the generic USB driver's probe, disconnect,
+ *     resume and suspend functions will be called in addition to the driver's
+ *     own, so this part of the setup does not need to be replicated.
  *
  * USB drivers must provide all the fields listed above except drvwrap.
  */
@@ -1242,6 +1245,7 @@ struct usb_device_driver {
        const struct attribute_group **dev_groups;
        struct usbdrv_wrap drvwrap;
        unsigned int supports_autosuspend:1;
+       unsigned int generic_subclass:1;
 };
 #define        to_usb_device_driver(d) container_of(d, struct usb_device_driver, \
                drvwrap.driver)