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@xxxxxxxxx>
---
drivers/usb/serial/generic.c | 47 ++++++++++++++++++++++++++++----------
drivers/usb/serial/usb-serial.c | 1 +
include/linux/usb/serial.h | 5 ++++
3 files changed, 40 insertions(+), 13 deletions(-)
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 9e103ba..65f13c8 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -166,12 +166,35 @@ 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);
@@ -190,16 +213,14 @@ 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,
@@ -241,7 +262,6 @@ err_urb:
*/
static int usb_serial_generic_write_start(struct usb_serial_port *port)
{
- unsigned char *data;
int result;
int count;
unsigned long flags;
@@ -254,10 +274,11 @@ 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 */
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 1b92442..8249fd8 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -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)
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 @@ 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);
--
1.7.0.2
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