su.c

自己根据lkd和情境分析

			info->MCR |= UART_MCR_OUT1;
		if (arg & TIOCM_OUT2)
			info->MCR |= UART_MCR_OUT2;
#endif
		break;
	case TIOCMBIC:
		if (arg & TIOCM_RTS)
			info->MCR &= ~UART_MCR_RTS;
		if (arg & TIOCM_DTR)
			info->MCR &= ~UART_MCR_DTR;
#ifdef TIOCM_OUT1
		if (arg & TIOCM_OUT1)
			info->MCR &= ~UART_MCR_OUT1;
		if (arg & TIOCM_OUT2)
			info->MCR &= ~UART_MCR_OUT2;
#endif
		break;
	case TIOCMSET:
		info->MCR = ((info->MCR & ~(UART_MCR_RTS |
#ifdef TIOCM_OUT1
					    UART_MCR_OUT1 |
					    UART_MCR_OUT2 |
#endif
					    UART_MCR_DTR))
			     | ((arg & TIOCM_RTS) ? UART_MCR_RTS : 0)
#ifdef TIOCM_OUT1
			     | ((arg & TIOCM_OUT1) ? UART_MCR_OUT1 : 0)
			     | ((arg & TIOCM_OUT2) ? UART_MCR_OUT2 : 0)
#endif
			     | ((arg & TIOCM_DTR) ? UART_MCR_DTR : 0));
		break;
	default:
		return -EINVAL;
	}
	save_flags(flags); cli();
	serial_out(info, UART_MCR, info->MCR);
	restore_flags(flags);
	return 0;
}

/*
 * su_break() --- routine which turns the break handling on or off
 */
static void
su_break(struct tty_struct *tty, int break_state)
{
	struct su_struct * info = (struct su_struct *)tty->driver_data;
	unsigned long flags;
	
	if (serial_paranoia_check(info, tty->device, "su_break"))
		return;

	if (!info->port)
		return;
	save_flags(flags); cli();
	if (break_state == -1)
		serial_out(info, UART_LCR,
			   serial_inp(info, UART_LCR) | UART_LCR_SBC);
	else
		serial_out(info, UART_LCR,
			   serial_inp(info, UART_LCR) & ~UART_LCR_SBC);
	restore_flags(flags);
}

static int
su_ioctl(struct tty_struct *tty, struct file * file,
		    unsigned int cmd, unsigned long arg)
{
	struct su_struct * info = (struct su_struct *)tty->driver_data;
	struct async_icount cprev, cnow;	/* kernel counter temps */
	struct serial_icounter_struct *p_cuser;	/* user space */

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

	if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
	    (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGSTRUCT) &&
	    (cmd != TIOCMIWAIT) && (cmd != TIOCGICOUNT)) {
		if (tty->flags & (1 << TTY_IO_ERROR))
		    return -EIO;
	}

	switch (cmd) {
		case TIOCMGET:
			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:
			return get_serial_info(info, (struct serial_struct *)arg);

		case TIOCSERGETLSR: /* Get line status register */
			return get_lsr_info(info, (unsigned int *) arg);

#if 0
		case TIOCSERGSTRUCT:
			if (copy_to_user((struct async_struct *) arg,
					 info, sizeof(struct async_struct)))
				return -EFAULT;
			return 0;
#endif
				
		/*
		 * Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
		 * - mask passed in arg for lines of interest
 		 *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
		 * Caller should use TIOCGICOUNT to see which one it was
		 */
		case TIOCMIWAIT:
			cli();
			/* note the counters on entry */
			cprev = info->icount;
			sti();
			while (1) {
				interruptible_sleep_on(&info->delta_msr_wait);
				/* see if a signal did it */
				if (signal_pending(current))
					return -ERESTARTSYS;
				cli();
				cnow = info->icount; /* atomic copy */
				sti();
				if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr && 
				    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
					return -EIO; /* no change => error */
				if ( ((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
				     ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
				     ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
				     ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts)) ) {
					return 0;
				}
				cprev = cnow;
			}
			/* NOTREACHED */

		/* 
		 * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
		 * Return: write counters to the user passed counter struct
		 * NB: both 1->0 and 0->1 transitions are counted except for
		 *     RI where only 0->1 is counted.
		 */
		case TIOCGICOUNT:
			cli();
			cnow = info->icount;
			sti();
			p_cuser = (struct serial_icounter_struct *) arg;
			if (put_user(cnow.cts, &p_cuser->cts) ||
			    put_user(cnow.dsr, &p_cuser->dsr) ||
			    put_user(cnow.rng, &p_cuser->rng) ||
			    put_user(cnow.dcd, &p_cuser->dcd))
				return -EFAULT;
			return 0;

		default:
			return -ENOIOCTLCMD;
		}
	/* return 0; */ /* Trigger warnings if fall through by a chance. */
}

static void
su_set_termios(struct tty_struct *tty, struct termios *old_termios)
{
	struct su_struct *info = (struct su_struct *)tty->driver_data;
	unsigned long flags;

	if (   (tty->termios->c_cflag == old_termios->c_cflag)
	    && (   RELEVANT_IFLAG(tty->termios->c_iflag) 
		== RELEVANT_IFLAG(old_termios->c_iflag)))
	  return;

	change_speed(info, old_termios);

	/* Handle transition to B0 status */
	if ((old_termios->c_cflag & CBAUD) &&
	    !(tty->termios->c_cflag & CBAUD)) {
		info->MCR &= ~(UART_MCR_DTR|UART_MCR_RTS);
		save_flags(flags); cli();
		serial_out(info, UART_MCR, info->MCR);
		restore_flags(flags);
	}

	/* Handle transition away from B0 status */
	if (!(old_termios->c_cflag & CBAUD) &&
	    (tty->termios->c_cflag & CBAUD)) {
		info->MCR |= UART_MCR_DTR;
		if (!(tty->termios->c_cflag & CRTSCTS) || 
		    !test_bit(TTY_THROTTLED, &tty->flags)) {
			info->MCR |= UART_MCR_RTS;
		}
		save_flags(flags); cli();
		serial_out(info, UART_MCR, info->MCR);
		restore_flags(flags);
	}
	
	/* Handle turning off CRTSCTS */
	if ((old_termios->c_cflag & CRTSCTS) &&
	    !(tty->termios->c_cflag & CRTSCTS)) {
		tty->hw_stopped = 0;
		su_start(tty);
	}

#if 0
	/*
	 * No need to wake up processes in open wait, since they
	 * sample the CLOCAL flag once, and don't recheck it.
	 * XXX  It's not clear whether the current behavior is correct
	 * or not.  Hence, this may change.....
	 */
	if (!(old_termios->c_cflag & CLOCAL) &&
	    (tty->termios->c_cflag & CLOCAL))
		wake_up_interruptible(&info->open_wait);
#endif
}

/*
 * ------------------------------------------------------------
 * su_close()
 * 
 * This routine is called when the serial port gets closed.  First, we
 * wait for the last remaining data to be sent.  Then, we unlink its
 * async structure from the interrupt chain if necessary, and we free
 * that IRQ if nothing is left in the chain.
 * ------------------------------------------------------------
 */
static void
su_close(struct tty_struct *tty, struct file * filp)
{
	struct su_struct *info = (struct su_struct *)tty->driver_data;
	unsigned long flags;

	if (!info || serial_paranoia_check(info, tty->device, "su_close"))
		return;

	save_flags(flags); cli();
	
	if (tty_hung_up_p(filp)) {
		DBG_CNT("before DEC-hung");
		MOD_DEC_USE_COUNT;
		restore_flags(flags);
		return;
	}
	
#ifdef SERIAL_DEBUG_OPEN
	printk("su_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("su_close: bad serial port count; tty->count is 1, "
		       "info->count is %d\n", info->count);
		info->count = 1;
	}
	if (--info->count < 0) {
		printk("su_close: bad serial port count for ttys%d: %d\n",
		       info->line, info->count);
		info->count = 0;
	}
	if (info->count) {
		DBG_CNT("before DEC-2");
		MOD_DEC_USE_COUNT;
		restore_flags(flags);
		return;
	}
	info->flags |= ASYNC_CLOSING;
	/*
	 * Save the termios structure, since this port may have
	 * separate termios for callout and dialin.
	 */
	if (info->flags & ASYNC_NORMAL_ACTIVE)
		info->normal_termios = *tty->termios;
	if (info->flags & ASYNC_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 != ASYNC_CLOSING_WAIT_NONE)
		tty_wait_until_sent(tty, info->closing_wait);
	/*
	 * At this point we stop accepting input.  To do this, we
	 * disable the receive line status interrupts, and tell the
	 * interrupt driver to stop checking the data ready bit in the
	 * line status register.
	 */
	info->IER &= ~UART_IER_RLSI;
	info->read_status_mask &= ~UART_LSR_DR;
	if (info->flags & ASYNC_INITIALIZED) {
		serial_out(info, UART_IER, info->IER);
		/*
		 * Before we drop DTR, make sure the UART transmitter
		 * has completely drained; this is especially
		 * important if there is a transmit FIFO!
		 */
		su_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 &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CALLOUT_ACTIVE|
			 ASYNC_CLOSING);
	wake_up_interruptible(&info->close_wait);
	MOD_DEC_USE_COUNT;
	restore_flags(flags);
}

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

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

	if (info->type == PORT_UNKNOWN)
		return;

	if (info->xmit_fifo_size == 0)
		return; /* Just in case ... */

	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.
	 * 
	 * Note: we have to use pretty tight timings here to satisfy
	 * the NIST-PCTS.
	 */
	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);
#ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
	printk("In su_wait_until_sent(%d) check=%lu...", timeout, char_time);
	printk("jiff=%lu...", jiffies);
#endif
	while (!((lsr = serial_inp(info, UART_LSR)) & UART_LSR_TEMT)) {
#ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
		printk("lsr = %d (jiff=%lu)...", lsr, jiffies);
#endif
		current->state = TASK_INTERRUPTIBLE;
		schedule_timeout(char_time);
		if (signal_pending(current))
			break;
		if (timeout && time_after(jiffies, orig_jiffies + timeout))
			break;
	}
#ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
	printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
#endif
}

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

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

	su_flush_buffer(tty);
	shutdown(info);
	info->event = 0;
	info->count = 0;
	info->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CALLOUT_ACTIVE);
	info->tty = 0;
	wake_up_interruptible(&info->open_wait);
}

/*
 * ------------------------------------------------------------
 * su_open() and friends
 * ------------------------------------------------------------
 */
static int
block_til_ready(struct tty_struct *tty, struct file * filp,
		struct su_struct *info)
{
	DECLARE_WAITQUEUE(wait, current);
	int		  retval;
	int		  do_clocal = 0, extra_count = 0;
	unsigned long	  flags;

	/*
	 * If the device is in the middle of being closed, then block
	 * until it's done, and then try again.
	 */
	if (tty_hung_up_p(filp) ||
	    (info->flags & ASYNC_CLOSING)) {
		if (info->flags & ASYNC_CLOSING)
			interruptible_sleep_on(&info->close_wait);
#ifdef SERIAL_DO_RESTART
		return ((info->flags & ASYNC_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 & ASYNC_NORMAL_ACTIVE)
			return -EBUSY;
		if ((info->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (info->flags & ASYNC_SESSION_LOCKOUT) &&
		    (info->session != current->session))
		    return -EBUSY;
		if ((info->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (info->flags & ASYNC_PGRP_LOCKOUT) &&
		    (info->pgrp != current->pgrp))
		    return -EBUSY;
		info->flags |= ASYNC_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 & ASYNC_CALLOUT_ACTIVE)
			return -EBUSY;
		info->flags |= ASYNC_NORMAL_ACTIVE;
		return 0;
	}

	if (info->flags & ASYNC_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
	 * su_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
	save_flags(flags); cli();
	if (!tty_hung_up_p(filp)) {
		extra_count = 1;
		info->count--;
	}
	restore_flags(flags);
	info->blocked_open++;
	while (1) {
		save_flags(flags); cli();
		if (!(info->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (tty->termios->c_cflag & CBAUD))
			serial_out(info, UART_MCR,
				   serial_inp(info, UART_MCR) |
				   (UART_MCR_DTR | UART_MCR_RTS));
		restore_flags(flags);
		set_current_state(TASK_INTERRUPTIBLE);
		if (tty_hung_up_p(filp) ||
		    !(info->flags & ASYNC_INITIALIZED)) {
#ifdef SERIAL_DO_RESTART
			if (info->flags & ASYNC_HUP_NOTIFY)
				retval = -EAGAIN;
			else
				retval = -ERESTARTSYS;	
#else