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/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index ad4823b..1a134f9 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -167,12 +167,35 @@
}
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 @@
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 @@
*/
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 @@
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 */