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USB: serial: add generic wait_until_sent implementation

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Add generic wait_until_sent implementation which polls for empty
hardware buffers using the new port-operation tx_empty.

The generic implementation will be used for all sub-drivers that
implement tx_empty but does not define wait_until_sent.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold
2013-05-08 17:51:43 +02:00
committed by Greg Kroah-Hartman
parent 0693196fe7
commit dcf0105039
3 changed files with 36 additions and 0 deletions
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31
drivers/usb/serial/generic.c
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@@ -253,6 +253,37 @@ int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
}
EXPORT_SYMBOL_GPL(usb_serial_generic_chars_in_buffer);
void usb_serial_generic_wait_until_sent(struct tty_struct *tty, long timeout)
{
struct usb_serial_port *port = tty->driver_data;
unsigned int bps;
unsigned long period;
unsigned long expire;
bps = tty_get_baud_rate(tty);
if (!bps)
bps = 9600; /* B0 */
/*
* Use a poll-period of roughly the time it takes to send one
* character or at least one jiffy.
*/
period = max_t(unsigned long, (10 * HZ / bps), 1);
period = min_t(unsigned long, period, timeout);
dev_dbg(&port->dev, "%s - timeout = %u ms, period = %u ms\n",
__func__, jiffies_to_msecs(timeout),
jiffies_to_msecs(period));
expire = jiffies + timeout;
while (!port->serial->type->tx_empty(port)) {
schedule_timeout_interruptible(period);
if (signal_pending(current))
break;
if (time_after(jiffies, expire))
break;
}
}
EXPORT_SYMBOL_GPL(usb_serial_generic_wait_until_sent);
static int usb_serial_generic_submit_read_urb(struct usb_serial_port *port,
int index, gfp_t mem_flags)
{