irtty-sir.c

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/*********************************************************************
 *                
 * Filename:      irtty-sir.c
 * Version:       2.0
 * Description:   IrDA line discipline implementation
 * Status:        Experimental.
 * Author:        Dag Brattli <[e-mail]>
 * Created at:    Tue Dec  9 21:18:38 1997
 * Modified at:   Sun Oct 27 22:13:30 2002
 * Modified by:   Martin Diehl <[e-mail]>
 * Sources:       slip.c by Laurence Culhane,   <[e-mail]>
 *                          Fred N. van Kempen, <[e-mail]>
 * 
 *     Copyright (c) 1998-2000 Dag Brattli,
 *     Copyright (c) 2002 Martin Diehl,
 *     All Rights Reserved.
 *      
 *     This program is free software; you can redistribute it and/or 
 *     modify it under the terms of the GNU General Public License as 
 *     published by the Free Software Foundation; either version 2 of 
 *     the License, or (at your option) any later version.
 *  
 *     Neither Dag Brattli nor University of Tromsø admit liability nor
 *     provide warranty for any of this software. This material is 
 *     provided "AS-IS" and at no charge.
 *     
 ********************************************************************/    

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/tty.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <linux/smp_lock.h>
#include <linux/delay.h>
#include <linux/mutex.h>

#include <net/irda/irda.h>
#include <net/irda/irda_device.h>

#include "sir-dev.h"
#include "irtty-sir.h"

static int qos_mtt_bits = 0x03;      /* 5 ms or more */

module_param(qos_mtt_bits, int, 0);
MODULE_PARM_DESC(qos_mtt_bits, "Minimum Turn Time");

/* ------------------------------------------------------- */

/* device configuration callbacks always invoked with irda-thread context */

/* find out, how many chars we have in buffers below us
 * this is allowed to lie, i.e. return less chars than we
 * actually have. The returned value is used to determine
 * how long the irdathread should wait before doing the
 * real blocking wait_until_sent()
 */

static int irtty_chars_in_buffer(struct sir_dev *dev)
{
	struct sirtty_cb *priv = dev->priv;

	IRDA_ASSERT(priv != NULL, return -1;);
	IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);

	return priv->tty->driver->chars_in_buffer(priv->tty);
}

/* Wait (sleep) until underlaying hardware finished transmission
 * i.e. hardware buffers are drained
 * this must block and not return before all characters are really sent
 *
 * If the tty sits on top of a 16550A-like uart, there are typically
 * up to 16 bytes in the fifo - f.e. 9600 bps 8N1 needs 16.7 msec
 *
 * With usbserial the uart-fifo is basically replaced by the converter's
 * outgoing endpoint buffer, which can usually hold 64 bytes (at least).
 * With pl2303 it appears we are safe with 60msec here.
 *
 * I really wish all serial drivers would provide
 * correct implementation of wait_until_sent()
 */

#define USBSERIAL_TX_DONE_DELAY	60

static void irtty_wait_until_sent(struct sir_dev *dev)
{
	struct sirtty_cb *priv = dev->priv;
	struct tty_struct *tty;

	IRDA_ASSERT(priv != NULL, return;);
	IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);

	tty = priv->tty;
	if (tty->driver->wait_until_sent) {
		lock_kernel();
		tty->driver->wait_until_sent(tty, msecs_to_jiffies(100));
		unlock_kernel();
	}
	else {
		msleep(USBSERIAL_TX_DONE_DELAY);
	}
}

/* 
 *  Function irtty_change_speed (dev, speed)
 *
 *    Change the speed of the serial port.
 *
 * This may sleep in set_termios (usbserial driver f.e.) and must
 * not be called from interrupt/timer/tasklet therefore.
 * All such invocations are deferred to kIrDAd now so we can sleep there.
 */

static int irtty_change_speed(struct sir_dev *dev, unsigned speed)
{
	struct sirtty_cb *priv = dev->priv;
	struct tty_struct *tty;
        struct ktermios old_termios;
	int cflag;

	IRDA_ASSERT(priv != NULL, return -1;);
	IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);

	tty = priv->tty;

	lock_kernel();
	old_termios = *(tty->termios);
	cflag = tty->termios->c_cflag;

	cflag &= ~CBAUD;

	IRDA_DEBUG(2, "%s(), Setting speed to %d\n", __FUNCTION__, speed);

	switch (speed) {
	case 1200:
		cflag |= B1200;
		break;
	case 2400:
		cflag |= B2400;
		break;
	case 4800:
		cflag |= B4800;
		break;
	case 19200:
		cflag |= B19200;
		break;
	case 38400:
		cflag |= B38400;
		break;
	case 57600:
		cflag |= B57600;
		break;
	case 115200:
		cflag |= B115200;
		break;
	case 9600:
	default:
		cflag |= B9600;
		break;
	}	

	tty->termios->c_cflag = cflag;
	if (tty->driver->set_termios)
		tty->driver->set_termios(tty, &old_termios);
	unlock_kernel();

	priv->io.speed = speed;

	return 0;
}

/*
 * Function irtty_set_dtr_rts (dev, dtr, rts)
 *
 *    This function can be used by dongles etc. to set or reset the status
 *    of the dtr and rts lines
 */

static int irtty_set_dtr_rts(struct sir_dev *dev, int dtr, int rts)
{
	struct sirtty_cb *priv = dev->priv;
	int set = 0;
	int clear = 0;

	IRDA_ASSERT(priv != NULL, return -1;);
	IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);

	if (rts)
		set |= TIOCM_RTS;
	else
		clear |= TIOCM_RTS;
	if (dtr)
		set |= TIOCM_DTR;
	else
		clear |= TIOCM_DTR;

	/*
	 * We can't use ioctl() because it expects a non-null file structure,
	 * and we don't have that here.
	 * This function is not yet defined for all tty driver, so
	 * let's be careful... Jean II
	 */
	IRDA_ASSERT(priv->tty->driver->tiocmset != NULL, return -1;);
	priv->tty->driver->tiocmset(priv->tty, NULL, set, clear);

	return 0;
}

/* ------------------------------------------------------- */

/* called from sir_dev when there is more data to send
 * context is either netdev->hard_xmit or some transmit-completion bh
 * i.e. we are under spinlock here and must not sleep.
 */

static int irtty_do_write(struct sir_dev *dev, const unsigned char *ptr, size_t len)
{
	struct sirtty_cb *priv = dev->priv;
	struct tty_struct *tty;
	int writelen;

	IRDA_ASSERT(priv != NULL, return -1;);
	IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);

	tty = priv->tty;
	if (!tty->driver->write)
		return 0;
	tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
	if (tty->driver->write_room) {
		writelen = tty->driver->write_room(tty);
		if (writelen > len)
			writelen = len;
	}
	else
		writelen = len;
	return tty->driver->write(tty, ptr, writelen);
}

/* ------------------------------------------------------- */

/* irda line discipline callbacks */

/* 
 *  Function irtty_receive_buf( tty, cp, count)
 *
 *    Handle the 'receiver data ready' interrupt.  This function is called
 *    by the 'tty_io' module in the kernel when a block of IrDA data has
 *    been received, which can now be decapsulated and delivered for
 *    further processing 
 *
 * calling context depends on underlying driver and tty->low_latency!
 * for example (low_latency: 1 / 0):
 * serial.c:	uart-interrupt / softint
 * usbserial:	urb-complete-interrupt / softint
 */

static void irtty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
			      char *fp, int count) 
{
	struct sir_dev *dev;
	struct sirtty_cb *priv = tty->disc_data;
	int	i;

	IRDA_ASSERT(priv != NULL, return;);
	IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);

	if (unlikely(count==0))		/* yes, this happens */
		return;

	dev = priv->dev;
	if (!dev) {
		IRDA_WARNING("%s(), not ready yet!\n", __FUNCTION__);
		return;
	}

	for (i = 0; i < count; i++) {
		/* 
		 *  Characters received with a parity error, etc?
		 */
 		if (fp && *fp++) { 
			IRDA_DEBUG(0, "Framing or parity error!\n");
			sirdev_receive(dev, NULL, 0);	/* notify sir_dev (updating stats) */
			return;
 		}
	}

	sirdev_receive(dev, cp, count);
}

/*
 * Function irtty_write_wakeup (tty)
 *
 *    Called by the driver when there's room for more data.  If we have
 *    more packets to send, we send them here.
 *
 */
static void irtty_write_wakeup(struct tty_struct *tty) 
{
	struct sirtty_cb *priv = tty->disc_data;

	IRDA_ASSERT(priv != NULL, return;);
	IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);

	tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);

	if (priv->dev)
		sirdev_write_complete(priv->dev);
}