USB: serial: generalise write buffer preparation
Generalise write buffer preparation.
This allows for drivers to manipulate (e.g. add headers) to bulk out
data before it is sent.
This adds a new function pointer to usb_serial_driver:
int (*prepare_write_buffer)(struct usb_serial_port *port,
void **dest, size_t size, const void *src, size_t count);
The function is generic and can be used with either kfifo-based or
multi-urb writes:
If *dest is NULL the implementation should allocate dest.
If src is NULL the implementation should use the port write fifo.
If not set, a generic implementation is used which simply uses memcpy or
kfifo_out.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 2a32837..a4c99ea 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -277,6 +277,9 @@
void (*write_bulk_callback)(struct urb *urb);
/* Called by the generic read bulk callback */
void (*process_read_urb)(struct urb *urb);
+ /* Called by the generic write implementation */
+ int (*prepare_write_buffer)(struct usb_serial_port *port,
+ void **dest, size_t size, const void *src, size_t count);
};
#define to_usb_serial_driver(d) \
container_of(d, struct usb_serial_driver, driver)
@@ -329,6 +332,8 @@
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_generic_prepare_write_buffer(struct usb_serial_port *port,
+ void **dest, size_t size, const void *src, size_t count);
extern int usb_serial_handle_sysrq_char(struct tty_struct *tty,
struct usb_serial_port *port,
unsigned int ch);