simserial.c

linux-2.4.29操作系统的源码

	struct serial_state *state;
	int		retval;

	if (!(info->flags & ASYNC_INITIALIZED)) return;

	state = info->state;

#ifdef SIMSERIAL_DEBUG
	printk("Shutting down serial port %d (irq %d)....", info->line,
	       state->irq);
#endif

	save_flags(flags); cli(); /* Disable interrupts */

	/*
	 * First unlink the serial port from the IRQ chain...
	 */
	if (info->next_port)
		info->next_port->prev_port = info->prev_port;
	if (info->prev_port)
		info->prev_port->next_port = info->next_port;
	else
		IRQ_ports[state->irq] = info->next_port;

	/*
	 * Free the IRQ, if necessary
	 */
	if (state->irq && (!IRQ_ports[state->irq] ||
			  !IRQ_ports[state->irq]->next_port)) {
		if (IRQ_ports[state->irq]) {
			free_irq(state->irq, NULL);
			retval = request_irq(state->irq, rs_interrupt_single,
					     IRQ_T(info), "serial", NULL);

			if (retval)
				printk(KERN_ERR "serial shutdown: request_irq: error %d"
				       "  Couldn't reacquire IRQ.\n", retval);
		} else
			free_irq(state->irq, NULL);
	}

	if (info->xmit.buf) {
		free_page((unsigned long) info->xmit.buf);
		info->xmit.buf = 0;
	}

	if (info->tty) set_bit(TTY_IO_ERROR, &info->tty->flags);

	info->flags &= ~ASYNC_INITIALIZED;
	restore_flags(flags);
}

/*
 * ------------------------------------------------------------
 * rs_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 rs_close(struct tty_struct *tty, struct file * filp)
{
	struct async_struct * info = (struct async_struct *)tty->driver_data;
	struct serial_state *state;
	unsigned long flags;

	if (!info ) return;

	state = info->state;

	save_flags(flags); cli();

	if (tty_hung_up_p(filp)) {
#ifdef SIMSERIAL_DEBUG
		printk("rs_close: hung_up\n");
#endif
		MOD_DEC_USE_COUNT;
		restore_flags(flags);
		return;
	}
#ifdef SIMSERIAL_DEBUG
	printk("rs_close ttys%d, count = %d\n", info->line, state->count);
#endif
	if ((tty->count == 1) && (state->count != 1)) {
		/*
		 * Uh, oh.  tty->count is 1, which means that the tty
		 * structure will be freed.  state->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(KERN_ERR "rs_close: bad serial port count; tty->count is 1, "
		       "state->count is %d\n", state->count);
		state->count = 1;
	}
	if (--state->count < 0) {
		printk(KERN_ERR "rs_close: bad serial port count for ttys%d: %d\n",
		       info->line, state->count);
		state->count = 0;
	}
	if (state->count) {
		MOD_DEC_USE_COUNT;
		restore_flags(flags);
		return;
	}
	info->flags |= ASYNC_CLOSING;
	restore_flags(flags);

	/*
	 * Now we wait for the transmit buffer to clear; and we notify
	 * the line discipline to only process XON/XOFF characters.
	 */
	shutdown(info);
	if (tty->driver.flush_buffer) tty->driver.flush_buffer(tty);
	if (tty->ldisc.flush_buffer) tty->ldisc.flush_buffer(tty);
	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;
}

/*
 * rs_wait_until_sent() --- wait until the transmitter is empty
 */
static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
{
}


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

#ifdef SIMSERIAL_DEBUG
	printk("rs_hangup: called\n");
#endif

	state = info->state;

	rs_flush_buffer(tty);
	if (info->flags & ASYNC_CLOSING)
		return;
	shutdown(info);

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


static int get_async_struct(int line, struct async_struct **ret_info)
{
	struct async_struct *info;
	struct serial_state *sstate;

	sstate = rs_table + line;
	sstate->count++;
	if (sstate->info) {
		*ret_info = sstate->info;
		return 0;
	}
	info = kmalloc(sizeof(struct async_struct), GFP_KERNEL);
	if (!info) {
		sstate->count--;
		return -ENOMEM;
	}
	memset(info, 0, sizeof(struct async_struct));
	init_waitqueue_head(&info->open_wait);
	init_waitqueue_head(&info->close_wait);
	init_waitqueue_head(&info->delta_msr_wait);
	info->magic = SERIAL_MAGIC;
	info->port = sstate->port;
	info->flags = sstate->flags;
	info->xmit_fifo_size = sstate->xmit_fifo_size;
	info->line = line;
	info->tqueue.routine = do_softint;
	info->tqueue.data = info;
	info->state = sstate;
	if (sstate->info) {
		kfree(info);
		*ret_info = sstate->info;
		return 0;
	}
	*ret_info = sstate->info = info;
	return 0;
}

static int
startup(struct async_struct *info)
{
	unsigned long flags;
	int	retval=0;
	void (*handler)(int, void *, struct pt_regs *);
	struct serial_state *state= info->state;
	unsigned long page;

	page = get_free_page(GFP_KERNEL);
	if (!page)
		return -ENOMEM;

	save_flags(flags); cli();

	if (info->flags & ASYNC_INITIALIZED) {
		free_page(page);
		goto errout;
	}

	if (!state->port || !state->type) {
		if (info->tty) set_bit(TTY_IO_ERROR, &info->tty->flags);
		free_page(page);
		goto errout;
	}
	if (info->xmit.buf)
		free_page(page);
	else
		info->xmit.buf = (unsigned char *) page;

#ifdef SIMSERIAL_DEBUG
	printk("startup: ttys%d (irq %d)...", info->line, state->irq);
#endif

	/*
	 * Allocate the IRQ if necessary
	 */
	if (state->irq && (!IRQ_ports[state->irq] ||
			  !IRQ_ports[state->irq]->next_port)) {
		if (IRQ_ports[state->irq]) {
			retval = -EBUSY;
			goto errout;
		} else
			handler = rs_interrupt_single;

		retval = request_irq(state->irq, handler, IRQ_T(info), "simserial", NULL);
		if (retval) {
			if (capable(CAP_SYS_ADMIN)) {
				if (info->tty)
					set_bit(TTY_IO_ERROR,
						&info->tty->flags);
				retval = 0;
			}
			goto errout;
		}
	}

	/*
	 * Insert serial port into IRQ chain.
	 */
	info->prev_port = 0;
	info->next_port = IRQ_ports[state->irq];
	if (info->next_port)
		info->next_port->prev_port = info;
	IRQ_ports[state->irq] = info;

	if (info->tty) clear_bit(TTY_IO_ERROR, &info->tty->flags);

	info->xmit.head = info->xmit.tail = 0;

#if 0
	/*
	 * Set up serial timers...
	 */
	timer_table[RS_TIMER].expires = jiffies + 2*HZ/100;
	timer_active |= 1 << RS_TIMER;
#endif

	/*
	 * Set up the tty->alt_speed kludge
	 */
	if (info->tty) {
		if ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
			info->tty->alt_speed = 57600;
		if ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
			info->tty->alt_speed = 115200;
		if ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
			info->tty->alt_speed = 230400;
		if ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
			info->tty->alt_speed = 460800;
	}

	info->flags |= ASYNC_INITIALIZED;
	restore_flags(flags);
	return 0;

errout:
	restore_flags(flags);
	return retval;
}


/*
 * 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 rs_open(struct tty_struct *tty, struct file * filp)
{
	struct async_struct	*info;
	int			retval, line;
	unsigned long		page;

	MOD_INC_USE_COUNT;
	line = MINOR(tty->device) - tty->driver.minor_start;
	if ((line < 0) || (line >= NR_PORTS)) {
		MOD_DEC_USE_COUNT;
		return -ENODEV;
	}
	retval = get_async_struct(line, &info);
	if (retval) {
		MOD_DEC_USE_COUNT;
		return retval;
	}
	tty->driver_data = info;
	info->tty = tty;

#ifdef SIMSERIAL_DEBUG
	printk("rs_open %s%d, count = %d\n", tty->driver.name, info->line,
	       info->state->count);
#endif
	info->tty->low_latency = (info->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

	if (!tmp_buf) {
		page = get_free_page(GFP_KERNEL);
		if (!page) {
			/* MOD_DEC_USE_COUNT; "info->tty" will cause this? */
			return -ENOMEM;
		}
		if (tmp_buf)
			free_page(page);
		else
			tmp_buf = (unsigned char *) page;
	}

	/*
	 * If the port is 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);
		/* MOD_DEC_USE_COUNT; "info->tty" will cause this? */
#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) {
		/* MOD_DEC_USE_COUNT; "info->tty" will cause this? */
		return retval;
	}

	if ((info->state->count == 1) &&
	    (info->flags & ASYNC_SPLIT_TERMIOS)) {
		if (tty->driver.subtype == SERIAL_TYPE_NORMAL)
			*tty->termios = info->state->normal_termios;
		else
			*tty->termios = info->state->callout_termios;
	}

	/*
	 * figure out which console to use (should be one already)
	 */
	console = console_drivers;
	while (console) {
		if ((console->flags & CON_ENABLED) && console->write) break;
		console = console->next;
	}

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

#ifdef SIMSERIAL_DEBUG
	printk("rs_open ttys%d successful\n", info->line);
#endif
	return 0;
}

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

static inline int line_info(char *buf, struct serial_state *state)
{
	return sprintf(buf, "%d: uart:%s port:%lX irq:%d\n",
		       state->line, uart_config[state->type].name,
		       state->port, state->irq);
}

static int rs_read_proc(char *page, char **start, off_t off, int count,
		 int *eof, void *data)
{
	int i, len = 0, l;
	off_t	begin = 0;

	len += sprintf(page, "simserinfo:1.0 driver:%s\n", serial_version);
	for (i = 0; i < NR_PORTS && len < 4000; i++) {
		l = line_info(page + len, &rs_table[i]);
		len += l;
		if (len+begin > off+count)
			goto done;
		if (len+begin < off) {
			begin += len;
			len = 0;
		}
	}
	*eof = 1;
done:
	if (off >= len+begin)
		return 0;
	*start = page + (begin-off);
	return ((count < begin+len-off) ? count : begin+len-off);
}

/*
 * ---------------------------------------------------------------------
 * rs_init() and friends
 *
 * rs_init() is called at boot-time to initialize the serial driver.
 * ---------------------------------------------------------------------
 */

/*
 * This routine prints out the appropriate serial driver version
 * number, and identifies which options were configured into this
 * driver.
 */
static inline void show_serial_version(void)
{
	printk(KERN_INFO "%s version %s with", serial_name, serial_version);
	printk(KERN_INFO " no serial options enabled\n");
}

/*
 * The serial driver boot-time initialization code!
 */
static int __init
simrs_init (void)
{
	int			i;
	struct serial_state	*state;

	show_serial_version();

	/* Initialize the tty_driver structure */

	memset(&serial_driver, 0, sizeof(struct tty_driver));
	serial_driver.magic = TTY_DRIVER_MAGIC;
	serial_driver.driver_name = "simserial";
	serial_driver.name = "ttyS";
	serial_driver.major = TTY_MAJOR;
	serial_driver.minor_start = 64;
	serial_driver.num = 1;
	serial_driver.type = TTY_DRIVER_TYPE_SERIAL;
	serial_driver.subtype = SERIAL_TYPE_NORMAL;
	serial_driver.init_termios = tty_std_termios;
	serial_driver.init_termios.c_cflag =
		B9600 | CS8 | CREAD | HUPCL | CLOCAL;
	serial_driver.flags = TTY_DRIVER_REAL_RAW;
	serial_driver.refcount = &serial_refcount;
	serial_driver.table = serial_table;
	serial_driver.termios = serial_termios;
	serial_driver.termios_locked = serial_termios_locked;

	serial_driver.open = rs_open;
	serial_driver.close = rs_close;
	serial_driver.write = rs_write;
	serial_driver.put_char = rs_put_char;
	serial_driver.flush_chars = rs_flush_chars;
	serial_driver.write_room = rs_write_room;
	serial_driver.chars_in_buffer = rs_chars_in_buffer;
	serial_driver.flush_buffer = rs_flush_buffer;
	serial_driver.ioctl = rs_ioctl;
	serial_driver.throttle = rs_throttle;
	serial_driver.unthrottle = rs_unthrottle;
	serial_driver.send_xchar = rs_send_xchar;
	serial_driver.set_termios = rs_set_termios;
	serial_driver.stop = rs_stop;
	serial_driver.start = rs_start;
	serial_driver.hangup = rs_hangup;
	serial_driver.break_ctl = rs_break;
	serial_driver.wait_until_sent = rs_wait_until_sent;
	serial_driver.read_proc = rs_read_proc;

	/*
	 * Let's have a little bit of fun !
	 */
	for (i = 0, state = rs_table; i < NR_PORTS; i++,state++) {

		if (state->type == PORT_UNKNOWN) continue;

		if (!state->irq) {
			state->irq = ia64_alloc_vector();
			ia64_ssc_connect_irq(KEYBOARD_INTR, state->irq);
		}

		printk(KERN_INFO "ttyS%02d at 0x%04lx (irq = %d) is a %s\n",
		       state->line,
		       state->port, state->irq,
		       uart_config[state->type].name);
	}
	/*
	 * The callout device is just like normal device except for
	 * major number and the subtype code.
	 */
	callout_driver = serial_driver;
	callout_driver.name = "cua";
	callout_driver.major = TTYAUX_MAJOR;
	callout_driver.subtype = SERIAL_TYPE_CALLOUT;
	callout_driver.read_proc = 0;
	callout_driver.proc_entry = 0;

	if (tty_register_driver(&serial_driver))
		panic("Couldn't register simserial driver\n");

	if (tty_register_driver(&callout_driver))
		panic("Couldn't register callout driver\n");

	return 0;
}

#ifndef MODULE
__initcall(simrs_init);
#endif