[PATCH v2 1/2] USB: core: add 'shutdown' callback to usb_driver

[Aditya Garg <gargaditya08@live.com>]

From: Kerem Karabay <kekrby@gmail.com>

Currently there is no standardized method for USB drivers to handle
shutdown events. This patch simplifies running code on shutdown for USB
devices by adding a shutdown callback to usb_driver.

Signed-off-by: Kerem Karabay <kekrby@gmail.com>
Signed-off-by: Aditya Garg <gargaditya08@live.com>
---
 drivers/usb/core/driver.c | 14 ++++++++++++++
 include/linux/usb.h       |  3 +++
 2 files changed, 17 insertions(+)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index e02ba15f6..b35734d03 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -517,6 +517,19 @@ static int usb_unbind_interface(struct device *dev)
 	return 0;
 }
 
+static void usb_shutdown_interface(struct device *dev)
+{
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct usb_driver *driver;
+
+	if (!dev->driver)
+		return;
+
+	driver = to_usb_driver(dev->driver);
+	if (driver->shutdown)
+		driver->shutdown(intf);
+}
+
 /**
  * usb_driver_claim_interface - bind a driver to an interface
  * @driver: the driver to be bound
@@ -1059,6 +1072,7 @@ int usb_register_driver(struct usb_driver *new_driver, struct module *owner,
 	new_driver->driver.bus = &usb_bus_type;
 	new_driver->driver.probe = usb_probe_interface;
 	new_driver->driver.remove = usb_unbind_interface;
+	new_driver->driver.shutdown = usb_shutdown_interface;
 	new_driver->driver.owner = owner;
 	new_driver->driver.mod_name = mod_name;
 	new_driver->driver.dev_groups = new_driver->dev_groups;
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 1913a1383..832997a9d 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1171,6 +1171,7 @@ extern ssize_t usb_show_dynids(struct usb_dynids *dynids, char *buf);
  *	post_reset method is called.
  * @post_reset: Called by usb_reset_device() after the device
  *	has been reset
+ * @shutdown: Called at shut-down time to quiesce the device.
  * @id_table: USB drivers use ID table to support hotplugging.
  *	Export this with MODULE_DEVICE_TABLE(usb,...).  This must be set
  *	or your driver's probe function will never get called.
@@ -1222,6 +1223,8 @@ struct usb_driver {
 	int (*pre_reset)(struct usb_interface *intf);
 	int (*post_reset)(struct usb_interface *intf);
 
+	void (*shutdown)(struct usb_interface *intf);
+
 	const struct usb_device_id *id_table;
 	const struct attribute_group **dev_groups;
 
-- 
2.43.0