zs.c

讲述linux的初始化过程

	result =  ((control & RTS) ? TIOCM_RTS: 0)
		| ((control & DTR) ? TIOCM_DTR: 0)
		| ((status  & DCD) ? TIOCM_CAR: 0)
		| ((status  & CTS) ? 0: TIOCM_CTS);
	put_user(result,value);
	return 0;
}

static int set_modem_info(struct dec_serial *info, unsigned int cmd,
			  unsigned int *value)
{
	int error;
	unsigned int arg, bits;

	error = verify_area(VERIFY_READ, value, sizeof(int));
	if (error)
		return error;
	get_user(arg, value);
	bits = (arg & TIOCM_RTS? RTS: 0) + (arg & TIOCM_DTR? DTR: 0);
	cli();
	switch (cmd) {
	case TIOCMBIS:
		info->zs_chan_a->curregs[5] |= bits;
		break;
	case TIOCMBIC:
		info->zs_chan_a->curregs[5] &= ~bits;
		break;
	case TIOCMSET:
		info->zs_chan_a->curregs[5] = (info->zs_chan_a->curregs[5] & ~(DTR | RTS)) | bits;
		break;
	default:
		sti();
		return -EINVAL;
	}
	write_zsreg(info->zs_chan_a, 5, info->zs_chan_a->curregs[5]);
	sti();
	return 0;
}

/*
 * rs_break - turn transmit break condition on/off
 */
static void rs_break(struct tty_struct *tty, int break_state)
{
	struct dec_serial *info = (struct dec_serial *) tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "rs_break"))
		return;
	if (!info->port)
		return;

	save_flags(flags); cli();
	if (break_state == -1)
		info->zs_channel->curregs[5] |= SND_BRK;
	else
		info->zs_channel->curregs[5] &= ~SND_BRK;
	write_zsreg(info->zs_channel, 5, info->zs_channel->curregs[5]);
	restore_flags(flags);
}

static int rs_ioctl(struct tty_struct *tty, struct file * file,
		    unsigned int cmd, unsigned long arg)
{
	int error;
	struct dec_serial * info = (struct dec_serial *)tty->driver_data;

#ifdef CONFIG_KGDB
	if (info->kgdb_channel)
		return -ENODEV;
#endif
	if (serial_paranoia_check(info, tty->device, "rs_ioctl"))
		return -ENODEV;

	if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
	    (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGWILD)  &&
	    (cmd != TIOCSERSWILD) && (cmd != TIOCSERGSTRUCT)) {
		if (tty->flags & (1 << TTY_IO_ERROR))
		    return -EIO;
	}
	
	switch (cmd) {
		case TIOCMGET:
			error = verify_area(VERIFY_WRITE, (void *) arg,
				sizeof(unsigned int));
			if (error)
				return error;
			return get_modem_info(info, (unsigned int *) arg);
		case TIOCMBIS:
		case TIOCMBIC:
		case TIOCMSET:
			return set_modem_info(info, cmd, (unsigned int *) arg);
		case TIOCGSERIAL:
			error = verify_area(VERIFY_WRITE, (void *) arg,
						sizeof(struct serial_struct));
			if (error)
				return error;
			return get_serial_info(info,
					       (struct serial_struct *) arg);
		case TIOCSSERIAL:
			return set_serial_info(info,
					       (struct serial_struct *) arg);
		case TIOCSERGETLSR: /* Get line status register */
			error = verify_area(VERIFY_WRITE, (void *) arg,
				sizeof(unsigned int));
			if (error)
				return error;
			else
			    return get_lsr_info(info, (unsigned int *) arg);

		case TIOCSERGSTRUCT:
			error = verify_area(VERIFY_WRITE, (void *) arg,
						sizeof(struct dec_serial));
			if (error)
				return error;
			copy_from_user((struct dec_serial *) arg,
				       info, sizeof(struct dec_serial));
			return 0;
			
		default:
			return -ENOIOCTLCMD;
		}
	return 0;
}

static void rs_set_termios(struct tty_struct *tty, struct termios *old_termios)
{
	struct dec_serial *info = (struct dec_serial *)tty->driver_data;
	int was_stopped;

	if (tty->termios->c_cflag == old_termios->c_cflag)
		return;
	was_stopped = info->tx_stopped;

	change_speed(info);

	if (was_stopped && !info->tx_stopped)
		rs_start(tty);
}

/*
 * ------------------------------------------------------------
 * rs_close()
 * 
 * This routine is called when the serial port gets closed.
 * Wait for the last remaining data to be sent.
 * ------------------------------------------------------------
 */
static void rs_close(struct tty_struct *tty, struct file * filp)
{
	struct dec_serial * info = (struct dec_serial *)tty->driver_data;
	unsigned long flags;

	if (!info || serial_paranoia_check(info, tty->device, "rs_close"))
		return;
	
	save_flags(flags); cli();
	
	if (tty_hung_up_p(filp)) {
		restore_flags(flags);
		return;
	}
	
#ifdef SERIAL_DEBUG_OPEN
	printk("rs_close ttys%d, count = %d\n", info->line, info->count);
#endif
	if ((tty->count == 1) && (info->count != 1)) {
		/*
		 * Uh, oh.  tty->count is 1, which means that the tty
		 * structure will be freed.  Info->count should always
		 * be one in these conditions.  If it's greater than
		 * one, we've got real problems, since it means the
		 * serial port won't be shutdown.
		 */
		printk("rs_close: bad serial port count; tty->count is 1, "
		       "info->count is %d\n", info->count);
		info->count = 1;
	}
	if (--info->count < 0) {
		printk("rs_close: bad serial port count for ttys%d: %d\n",
		       info->line, info->count);
		info->count = 0;
	}
	if (info->count) {
		restore_flags(flags);
		return;
	}
	info->flags |= ZILOG_CLOSING;
	/*
	 * Save the termios structure, since this port may have
	 * separate termios for callout and dialin.
	 */
	if (info->flags & ZILOG_NORMAL_ACTIVE)
		info->normal_termios = *tty->termios;
	if (info->flags & ZILOG_CALLOUT_ACTIVE)
		info->callout_termios = *tty->termios;
	/*
	 * Now we wait for the transmit buffer to clear; and we notify 
	 * the line discipline to only process XON/XOFF characters.
	 */
	tty->closing = 1;
	if (info->closing_wait != ZILOG_CLOSING_WAIT_NONE)
		tty_wait_until_sent(tty, info->closing_wait);
	/*
	 * At this point we stop accepting input.  To do this, we
	 * disable the receiver and receive interrupts.
	 */
	info->zs_channel->curregs[3] &= ~RxENABLE;
	write_zsreg(info->zs_channel, 3, info->zs_channel->curregs[3]);
	info->zs_channel->curregs[1] = 0;	/* disable any rx ints */
	write_zsreg(info->zs_channel, 1, info->zs_channel->curregs[1]);
	ZS_CLEARFIFO(info->zs_channel);
	if (info->flags & ZILOG_INITIALIZED) {
		/*
		 * Before we drop DTR, make sure the SCC transmitter
		 * has completely drained.
		 */
		rs_wait_until_sent(tty, info->timeout);
	}

	shutdown(info);
	if (tty->driver.flush_buffer)
		tty->driver.flush_buffer(tty);
	if (tty->ldisc.flush_buffer)
		tty->ldisc.flush_buffer(tty);
	tty->closing = 0;
	info->event = 0;
	info->tty = 0;
	if (info->blocked_open) {
		if (info->close_delay) {
			current->state = TASK_INTERRUPTIBLE;
			schedule_timeout(info->close_delay);
		}
		wake_up_interruptible(&info->open_wait);
	}
	info->flags &= ~(ZILOG_NORMAL_ACTIVE|ZILOG_CALLOUT_ACTIVE|
			 ZILOG_CLOSING);
	wake_up_interruptible(&info->close_wait);
	restore_flags(flags);
}

/*
 * rs_wait_until_sent() --- wait until the transmitter is empty
 */
static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
{
	struct dec_serial *info = (struct dec_serial *) tty->driver_data;
	unsigned long orig_jiffies, char_time;

	if (serial_paranoia_check(info, tty->device, "rs_wait_until_sent"))
		return;

	orig_jiffies = jiffies;
	/*
	 * Set the check interval to be 1/5 of the estimated time to
	 * send a single character, and make it at least 1.  The check
	 * interval should also be less than the timeout.
	 */
	char_time = (info->timeout - HZ/50) / info->xmit_fifo_size;
	char_time = char_time / 5;
	if (char_time == 0)
		char_time = 1;
	if (timeout)
		char_time = MIN(char_time, timeout);
	while ((read_zsreg(info->zs_channel, 1) & Tx_BUF_EMP) == 0) {
		current->state = TASK_INTERRUPTIBLE;
		schedule_timeout(char_time);
		if (signal_pending(current))
			break;
		if (timeout && ((orig_jiffies + timeout) < jiffies))
			break;
	}
	current->state = TASK_RUNNING;
}

/*
 * rs_hangup() --- called by tty_hangup() when a hangup is signaled.
 */
void rs_hangup(struct tty_struct *tty)
{
	struct dec_serial * info = (struct dec_serial *)tty->driver_data;

	if (serial_paranoia_check(info, tty->device, "rs_hangup"))
		return;

	rs_flush_buffer(tty);
	shutdown(info);
	info->event = 0;
	info->count = 0;
	info->flags &= ~(ZILOG_NORMAL_ACTIVE|ZILOG_CALLOUT_ACTIVE);
	info->tty = 0;
	wake_up_interruptible(&info->open_wait);
}

/*
 * ------------------------------------------------------------
 * rs_open() and friends
 * ------------------------------------------------------------
 */
static int block_til_ready(struct tty_struct *tty, struct file * filp,
			   struct dec_serial *info)
{
	DECLARE_WAITQUEUE(wait, current);
	int		retval;
	int		do_clocal = 0;

	/*
	 * If the device is in the middle of being closed, then block
	 * until it's done, and then try again.
	 */
	if (info->flags & ZILOG_CLOSING) {
		interruptible_sleep_on(&info->close_wait);
#ifdef SERIAL_DO_RESTART
		return ((info->flags & ZILOG_HUP_NOTIFY) ?
			-EAGAIN : -ERESTARTSYS);
#else
		return -EAGAIN;
#endif
	}

	/*
	 * If this is a callout device, then just make sure the normal
	 * device isn't being used.
	 */
	if (tty->driver.subtype == SERIAL_TYPE_CALLOUT) {
		if (info->flags & ZILOG_NORMAL_ACTIVE)
			return -EBUSY;
		if ((info->flags & ZILOG_CALLOUT_ACTIVE) &&
		    (info->flags & ZILOG_SESSION_LOCKOUT) &&
		    (info->session != current->session))
		    return -EBUSY;
		if ((info->flags & ZILOG_CALLOUT_ACTIVE) &&
		    (info->flags & ZILOG_PGRP_LOCKOUT) &&
		    (info->pgrp != current->pgrp))
		    return -EBUSY;
		info->flags |= ZILOG_CALLOUT_ACTIVE;
		return 0;
	}
	
	/*
	 * If non-blocking mode is set, or the port is not enabled,
	 * then make the check up front and then exit.
	 */
	if ((filp->f_flags & O_NONBLOCK) ||
	    (tty->flags & (1 << TTY_IO_ERROR))) {
		if (info->flags & ZILOG_CALLOUT_ACTIVE)
			return -EBUSY;
		info->flags |= ZILOG_NORMAL_ACTIVE;
		return 0;
	}

	if (info->flags & ZILOG_CALLOUT_ACTIVE) {
		if (info->normal_termios.c_cflag & CLOCAL)
			do_clocal = 1;
	} else {
		if (tty->termios->c_cflag & CLOCAL)
			do_clocal = 1;
	}
	
	/*
	 * Block waiting for the carrier detect and the line to become
	 * free (i.e., not in use by the callout).  While we are in
	 * this loop, info->count is dropped by one, so that
	 * rs_close() knows when to free things.  We restore it upon
	 * exit, either normal or abnormal.
	 */
	retval = 0;
	add_wait_queue(&info->open_wait, &wait);
#ifdef SERIAL_DEBUG_OPEN
	printk("block_til_ready before block: ttys%d, count = %d\n",
	       info->line, info->count);
#endif
	cli();
	if (!tty_hung_up_p(filp)) 
		info->count--;
	sti();
	info->blocked_open++;
	while (1) {
		cli();
		if (!(info->flags & ZILOG_CALLOUT_ACTIVE) &&
		    (tty->termios->c_cflag & CBAUD))
			zs_rtsdtr(info, 1);
		sti();
		set_current_state(TASK_INTERRUPTIBLE);
		if (tty_hung_up_p(filp) ||
		    !(info->flags & ZILOG_INITIALIZED)) {
#ifdef SERIAL_DO_RESTART
			if (info->flags & ZILOG_HUP_NOTIFY)
				retval = -EAGAIN;
			else
				retval = -ERESTARTSYS;	
#else
			retval = -EAGAIN;
#endif
			break;
		}
		if (!(info->flags & ZILOG_CALLOUT_ACTIVE) &&
		    !(info->flags & ZILOG_CLOSING) &&
		    (do_clocal || (read_zsreg(info->zs_channel, 0) & DCD)))
			break;
		if (signal_pending(current)) {
			retval = -ERESTARTSYS;
			break;
		}
#ifdef SERIAL_DEBUG_OPEN
		printk("block_til_ready blocking: ttys%d, count = %d\n",
		       info->line, info->count);
#endif
		schedule();
	}
	current->state = TASK_RUNNING;
	remove_wait_queue(&info->open_wait, &wait);
	if (!tty_hung_up_p(filp))
		info->count++;
	info->blocked_open--;
#ifdef SERIAL_DEBUG_OPEN
	printk("block_til_ready after blocking: ttys%d, count = %d\n",
	       info->line, info->count);
#endif
	if (retval)
		return retval;
	info->flags |= ZILOG_NORMAL_ACTIVE;
	return 0;
}	

/*
 * This routine is called whenever a serial port is opened.  It
 * enables interrupts for a serial port, linking in its ZILOG structure into
 * the IRQ chain.   It also performs the serial-specific
 * initialization for the tty structure.
 */
int rs_open(struct tty_struct *tty, struct file * filp)
{
	struct dec_serial	*info;
	int 			retval, line;

	line = MINOR(tty->device) - tty->driver.minor_start;
	if ((line < 0) || (line >= zs_channels_found))
		return -ENODEV;
	info = zs_soft + line;

#ifdef CONFIG_KGDB
	if (info->kgdb_channel)
		return -ENODEV;
#endif
	if (serial_paranoia_check(info, tty->device, "rs_open"))
		return -ENODEV;
#ifdef SERIAL_DEBUG_OPEN
	printk("rs_open %s%d, count = %d\n", tty->driver.name, info->line,
	       info->count);
#endif

	info->count++;
	tty->driver_data = info;
	info->tty = tty;

	/*
	 * If the port is the middle of closing, bail out now
	 */
	if (tty_hung_up_p(filp) ||
	    (info->flags & ZILOG_CLOSING)) {
		if (info->flags & ZILOG_CLOSING)
			interruptible_sleep_on(&info->close_wait);
#ifdef SERIAL_DO_RESTART
		return ((info->flags & ZILOG_HUP_NOTIFY) ?
			-EAGAIN : -ERESTARTSYS);
#else
		return -EAGAIN;
#endif
	}

	/*
	 * Start up serial port
	 */
	retval = startup(info);
	if (retval)
		return retval;

	retval = block_til_ready(tty, filp, info);
	if (retval) {
#ifdef SERIAL_DEBUG_OPEN
		printk("rs_open returning after block_til_ready with %d\n",
		       retval);
#endif
		return retval;
	}

	if ((info->count == 1) && (info->flags & ZILOG_SPLIT_TERMIOS)) {
		if (tty->driver.subtype == SERIAL_TYPE_NORMAL)
			*tty->termios = info->normal_termios;
		else 
			*tty->termios = info->callout_termios;
		change_speed(info);
	}
#ifdef CONFIG_SERIAL_CONSOLE
	if (sercons.cflag && sercons.index == line) {
		tty->termios->c_cflag = sercons.cflag;
		sercons.cflag = 0;
		change_speed(info);
	}
#endif

	info->session = current->session;
	info->pgrp = current->pgrp;

#ifdef SERIAL_DEBUG_OPEN
	printk("rs_open ttys%d successful...", info->line);
#endif
/* tty->low_latency = 1; */
	return 0;
}

/* Finally, routines used to initialize the serial driver. */

static void __init show_serial_version(void)
{
	printk("DECstation Z8530 serial driver version 0.03\n");
}

/*  Initialize Z8530s zs_channels
 */

static void __init probe_sccs(void)
{