Commit eaa3bcb0 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
Browse files

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: default avatarJohan Hovold <jhovold@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 25d514ca

drivers/usb/serial/generic.c

+34 −13
Original line number Diff line number Diff line
@@ -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 */

drivers/usb/serial/usb-serial.c

+1 −0
Original line number Diff line number Diff line
@@ -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)

include/linux/usb/serial.h

+5 −0
Original line number Diff line number Diff line
@@ -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);

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