sab82532.c

讲述linux的初始化过程

		 * 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;
			error = put_user(cnow.cts, &p_cuser->cts);
			if (error) return error;
			error = put_user(cnow.dsr, &p_cuser->dsr);
			if (error) return error;
			error = put_user(cnow.rng, &p_cuser->rng);
			if (error) return error;
			error = put_user(cnow.dcd, &p_cuser->dcd);
			if (error) return error;
			return 0;

		default:
			return -ENOIOCTLCMD;
		}
	return 0;
}

static void sab82532_set_termios(struct tty_struct *tty,
				 struct termios *old_termios)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;

	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);

	/* Handle transition to B0 status */
	if ((old_termios->c_cflag & CBAUD) &&
	    !(tty->termios->c_cflag & CBAUD)) {
		writeb(readb(&info->regs->w.mode) | SAB82532_MODE_FRTS, &info->regs->w.mode);
		writeb(readb(&info->regs->w.mode) | SAB82532_MODE_RTS, &info->regs->w.mode);
		writeb(readb(&info->regs->w.pvr) | info->pvr_dtr_bit, &info->regs->w.pvr);
	}
	
	/* Handle transition away from B0 status */
	if (!(old_termios->c_cflag & CBAUD) &&
	    (tty->termios->c_cflag & CBAUD)) {
		writeb(readb(&info->regs->w.pvr) & ~(info->pvr_dtr_bit), &info->regs->w.pvr);
		if (!tty->hw_stopped ||
		    !(tty->termios->c_cflag & CRTSCTS)) {
			writeb(readb(&info->regs->w.mode) & ~(SAB82532_MODE_FRTS), &info->regs->w.mode);
			writeb(readb(&info->regs->w.mode) | SAB82532_MODE_RTS, &info->regs->w.mode);
		}
	}
	
	/* Handle turning off CRTSCTS */
	if ((old_termios->c_cflag & CRTSCTS) &&
	    !(tty->termios->c_cflag & CRTSCTS)) {
		tty->hw_stopped = 0;
		sab82532_start(tty);
	}
}

/*
 * ------------------------------------------------------------
 * sab82532_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 sab82532_close(struct tty_struct *tty, struct file * filp)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
	unsigned long flags;

	if (!info || serial_paranoia_check(info, tty->device, "sab82532_close"))
		return;

	save_flags(flags); cli();

	if (tty_hung_up_p(filp)) {
		MOD_DEC_USE_COUNT;
		restore_flags(flags);
		return;
	}

#ifdef SERIAL_DEBUG_OPEN
	printk("sab82532_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("sab82532_close: bad serial port count; tty->count is 1,"
		       " info->count is %d\n", info->count);
		info->count = 1;
	}
	if (--info->count < 0) {
		printk("sab82532_close: bad serial port count for ttys%d: %d\n",
		       info->line, info->count);
		info->count = 0;
	}
	if (info->count) {
		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 turn off
	 * the receiver.
	 */
	info->interrupt_mask0 |= SAB82532_IMR0_TCD;
	writeb(info->interrupt_mask0, &info->regs->w.imr0);
	if (info->flags & ASYNC_INITIALIZED) {
		/*
		 * Before we drop DTR, make sure the UART transmitter
		 * has completely drained; this is especially
		 * important if there is a transmit FIFO!
		 */
		sab82532_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);
}

/*
 * sab82532_wait_until_sent() --- wait until the transmitter is empty
 */
static void sab82532_wait_until_sent(struct tty_struct *tty, int timeout)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
	unsigned long orig_jiffies, char_time;

	if (serial_paranoia_check(info,tty->device,"sab82532_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.
	 * 
	 * 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_WAIT_UNTIL_SENT
	printk("In sab82532_wait_until_sent(%d) check=%lu...", timeout, char_time);
	printk("jiff=%lu...", jiffies);
#endif
	while (info->xmit_cnt || !info->all_sent) {
		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_WAIT_UNTIL_SENT
	printk("xmit_cnt = %d, alls = %d (jiff=%lu)...done\n", info->xmit_cnt, info->all_sent, jiffies);
#endif
}

/*
 * sab82532_hangup() --- called by tty_hangup() when a hangup is signaled.
 */
static void sab82532_hangup(struct tty_struct *tty)
{
	struct sab82532 * info = (struct sab82532 *)tty->driver_data;

	if (serial_paranoia_check(info, tty->device, "sab82532_hangup"))
		return;

#ifdef CONFIG_SERIAL_CONSOLE
	if (info->is_console)
		return;
#endif

	sab82532_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);
}

/*
 * ------------------------------------------------------------
 * sab82532_open() and friends
 * ------------------------------------------------------------
 */
static int block_til_ready(struct tty_struct *tty, struct file * filp,
			   struct sab82532 *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 (tty_hung_up_p(filp) ||
	    (info->flags & ASYNC_CLOSING)) {
		if (info->flags & ASYNC_CLOSING)
			interruptible_sleep_on(&info->close_wait);
#ifdef SERIAL_DO_RESTART
		if (info->flags & ASYNC_HUP_NOTIFY)
			return -EAGAIN;
		else
			return -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
	 * sab82532_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 & ASYNC_CALLOUT_ACTIVE) &&
		    (tty->termios->c_cflag & CBAUD)) {
			writeb(readb(&info->regs->rw.pvr) & ~(info->pvr_dtr_bit), &info->regs->rw.pvr);
			writeb(readb(&info->regs->rw.mode) | SAB82532_MODE_FRTS, &info->regs->rw.mode);
			writeb(readb(&info->regs->rw.mode) & ~(SAB82532_MODE_RTS), &info->regs->rw.mode);
		}
		sti();
		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
			retval = -EAGAIN;
#endif
			break;
		}
		if (!(info->flags & ASYNC_CALLOUT_ACTIVE) &&
		    !(info->flags & ASYNC_CLOSING) &&
		    (do_clocal || !(readb(&info->regs->r.vstr) & SAB82532_VSTR_CD)))
			break;
		if (signal_pending(current)) {
			retval = -ERESTARTSYS;
			break;
		}
#ifdef SERIAL_DEBUG_OPEN
		printk("block_til_ready blocking: ttyS%d, count = %d, flags = %x, clocal = %d, vstr = %02x\n",
		       info->line, info->count, info->flags, do_clocal, readb(&info->regs->r.vstr));
#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 |= ASYNC_NORMAL_ACTIVE;
	return 0;
}

/*
 * This routine is called whenever a serial port is opened.  It
 * enables interrupts for a serial port, linking in its async structure into
 * the IRQ chain.   It also performs the serial-specific
 * initialization for the tty structure.
 */
static int sab82532_open(struct tty_struct *tty, struct file * filp)
{
	struct sab82532	*info = sab82532_chain;
	int retval, line;
	unsigned long page;

#ifdef SERIAL_DEBUG_OPEN
	printk("sab82532_open: count = %d\n", info->count);
#endif

	line = MINOR(tty->device) - tty->driver.minor_start;
	if ((line < 0) || (line >= NR_PORTS))
		return -ENODEV;

	while (info) {
		if (info->line == line)
			break;
		info = info->next;
	}
	if (!info) {
		printk("sab82532_open: can't find info for line %d\n",
		       line);
		return -ENODEV;
	}

	if (serial_paranoia_check(info, tty->device, "sab82532_open"))
		return -ENODEV;

#ifdef SERIAL_DEBUG_OPEN
	printk("sab82532_open %s%d, count = %d\n", tty->driver.name, info->line,
	       info->count);
#endif

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

	if (!tmp_buf) {
		page = get_free_page(GFP_KERNEL);
		if (!page)
			return -ENOMEM;
		if (tmp_buf)
			free_page(page);
		else
			tmp_buf = (unsigned char *) page;
	}

	/*
	 * If the port is in the middle of closing, bail out now.
	 */
	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
	}

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

	MOD_INC_USE_COUNT;
	retval = block_til_ready(tty, filp, info);
	if (retval) {
#ifdef SERIAL_DEBUG_OPEN
		printk("sab82532_open returning after block_til_ready with %d\n",
		       retval);
#endif
		return retval;
	}

	if ((info->count == 1) &&
	    (info->flags & ASYNC_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 (sab82532_console.cflag && sab82532_console.index == line) {
		tty->termios->c_cflag = sab82532_console.cflag;
		sab82532_console.cflag = 0;
		change_speed(info);
	}
#endif

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

#ifdef SERIAL_DEBUG_OPEN
	printk("sab82532_open ttys%d successful... count %d", info->line, info->count);
#endif
	return 0;
}

/*
 * /proc fs routines....
 */

static __inline__ int
line_info(char *buf, struct sab82532 *info)
{