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USB: serial: generalise write buffer preparation

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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>
This commit is contained in:
Johan Hovold 2010-03-17 23:06:08 +01:00 committed by Greg Kroah-Hartman
parent 25d514ca22
commit eaa3bcb06a
3 changed files with 40 additions and 13 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

47
drivers/usb/serial/generic.c
View file

@ -167,12 +167,35 @@ void usb_serial_generic_close(struct usb_serial_port *port)
}
EXPORT_SYMBOL_GPL(usb_serial_generic_close);
int usb_serial_generic_prepare_write_buffer(struct usb_serial_port *port,
void **dest, size_t size, const void *src, size_t count)
{
if (!*dest) {
size = count;
*dest = kmalloc(count, GFP_ATOMIC);
if (!*dest) {
dev_err(&port->dev, "%s - could not allocate buffer\n",
__func__);
return -ENOMEM;
}
}
if (src) {
count = size;
memcpy(*dest, src, size);
} else {
count = kfifo_out_locked(&port->write_fifo, *dest, size,
&port->lock);
}
return count;
}
EXPORT_SYMBOL_GPL(usb_serial_generic_prepare_write_buffer);
static int usb_serial_multi_urb_write(struct tty_struct *tty,
struct usb_serial_port *port, const unsigned char *buf, int count)
{
unsigned long flags;
struct urb *urb;
unsigned char *buffer;
void *buffer;
int status;
spin_lock_irqsave(&port->lock, flags);
@ -191,16 +214,14 @@ static int usb_serial_multi_urb_write(struct tty_struct *tty,
goto err_urb;
}
buffer = NULL;
count = min_t(int, count, PAGE_SIZE);
buffer = kmalloc(count, GFP_ATOMIC);
if (!buffer) {
dev_err(&port->dev, "%s - could not allocate buffer\n",
__func__);
status = -ENOMEM;
count = port->serial->type->prepare_write_buffer(port, &buffer, 0,
buf, count);
if (count < 0) {
status = count;
goto err_buf;
}
memcpy(buffer, buf, count);
usb_serial_debug_data(debug, &port->dev, __func__, count, buffer);
usb_fill_bulk_urb(urb, port->serial->dev,
usb_sndbulkpipe(port->serial->dev,
@ -242,7 +263,6 @@ err_urb:
*/
static int usb_serial_generic_write_start(struct usb_serial_port *port)
{
unsigned char *data;
int result;
int count;
unsigned long flags;
@ -255,10 +275,11 @@ static int usb_serial_generic_write_start(struct usb_serial_port *port)
port->write_urb_busy = 1;
spin_unlock_irqrestore(&port->lock, flags);
data = port->write_urb->transfer_buffer;
count = kfifo_out_locked(&port->write_fifo, data, port->bulk_out_size, &port->lock);
usb_serial_debug_data(debug, &port->dev, __func__, count, data);
count = port->serial->type->prepare_write_buffer(port,
&port->write_urb->transfer_buffer,
port->bulk_out_size, NULL, 0);
usb_serial_debug_data(debug, &port->dev, __func__,
count, port->write_urb->transfer_buffer);
port->write_urb->transfer_buffer_length = count;
/* send the data out the bulk port */

1
drivers/usb/serial/usb-serial.c
View file

@ -1299,6 +1299,7 @@ static void fixup_generic(struct usb_serial_driver *device)
set_to_generic_if_null(device, disconnect);
set_to_generic_if_null(device, release);
set_to_generic_if_null(device, process_read_urb);
set_to_generic_if_null(device, prepare_write_buffer);
}
int usb_serial_register(struct usb_serial_driver *driver)

5
include/linux/usb/serial.h
View file

@ -277,6 +277,9 @@ struct usb_serial_driver {
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 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_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);