USB: serial: generalise generic read implementation

Add process_read_urb to usb_serial_driver so that a driver can rely on
the generic read (and throttle) mechanism but still do device specific
processing of incoming data (such as adding tty_flags before pushing to
line discipline).

The default generic implementation handles sysrq for consoles but
otherwise simply pushes to tty.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/generic.c

@@ -408,7 +408,7 @@ int usb_serial_generic_submit_read_urb(struct usb_serial_port *port,
 }
 EXPORT_SYMBOL_GPL(usb_serial_generic_submit_read_urb);
 
-static void usb_serial_generic_process_read_urb(struct urb *urb)
+void usb_serial_generic_process_read_urb(struct urb *urb)
 {
 	struct usb_serial_port *port = urb->context;
 	struct tty_struct *tty;
@@ -433,6 +433,7 @@ static void usb_serial_generic_process_read_urb(struct urb *urb)
 	tty_flip_buffer_push(tty);
 	tty_kref_put(tty);
 }
+EXPORT_SYMBOL_GPL(usb_serial_generic_process_read_urb);
 
 void usb_serial_generic_read_bulk_callback(struct urb *urb)
 {
@@ -451,7 +452,7 @@ void usb_serial_generic_read_bulk_callback(struct urb *urb)
 
 	usb_serial_debug_data(debug, &port->dev, __func__,
 						urb->actual_length, data);
-	usb_serial_generic_process_read_urb(urb);
+	port->serial->type->process_read_urb(urb);
 
 	/* Throttle the device if requested by tty */
 	spin_lock_irqsave(&port->lock, flags);

drivers/usb/serial/usb-serial.c

@@ -1298,6 +1298,7 @@ static void fixup_generic(struct usb_serial_driver *device)
 	set_to_generic_if_null(device, write_bulk_callback);
 	set_to_generic_if_null(device, disconnect);
 	set_to_generic_if_null(device, release);
+	set_to_generic_if_null(device, process_read_urb);
 }
 
 int usb_serial_register(struct usb_serial_driver *driver)

include/linux/usb/serial.h

@@ -272,6 +272,8 @@ struct usb_serial_driver {
 	void (*write_int_callback)(struct urb *urb);
 	void (*read_bulk_callback)(struct urb *urb);
 	void (*write_bulk_callback)(struct urb *urb);
+	/* Called by the generic read bulk callback */
+	void (*process_read_urb)(struct urb *urb);
 };
 #define to_usb_serial_driver(d) \
 	container_of(d, struct usb_serial_driver, driver)
@@ -323,6 +325,7 @@ extern int usb_serial_generic_register(int debug);
 extern void usb_serial_generic_deregister(void);
 extern int usb_serial_generic_submit_read_urb(struct usb_serial_port *port,
 						 gfp_t mem_flags);
+extern void usb_serial_generic_process_read_urb(struct urb *urb);
 extern int usb_serial_handle_sysrq_char(struct tty_struct *tty,
 					struct usb_serial_port *port,
 					unsigned int ch);