tty_io.c

gives an orthogonal feeling to tty s, be they consoles or rs-channels. It also implements echoing, c

 * 
 * This code could be nicer; ideally it should send a HUP, wait a few
 * seconds, then send a INT, and then a KILL signal.  But you then
 * have to coordinate with the init process, since all processes associated
 * with the current tty must be dead before the new getty is allowed
 * to spawn.
 *
 * Now, if it would be correct ;-/ The current code has a nasty hole -
 * it doesn't catch files in flight. We may send the descriptor to ourselves
 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
 *
 * Nasty bug: do_SAK is being called in interrupt context.  This can
 * deadlock.  We punt it up to process context.  AKPM - 16Mar2001
 */
static void __do_SAK(void *arg)
{
#ifdef TTY_SOFT_SAK
	tty_hangup(tty);
#else
	struct tty_struct *tty = arg;
	struct task_struct *p;
	int session;
	int		i;
	struct file	*filp;
	
	if (!tty)
		return;
	session  = tty->session;
	if (tty->ldisc.flush_buffer)
		tty->ldisc.flush_buffer(tty);
	if (tty->driver.flush_buffer)
		tty->driver.flush_buffer(tty);
	read_lock(&tasklist_lock);
	for_each_task(p) {
		if ((p->tty == tty) ||
		    ((session > 0) && (p->session == session))) {
			send_sig(SIGKILL, p, 1);
			continue;
		}
		task_lock(p);
		if (p->files) {
			read_lock(&p->files->file_lock);
			for (i=0; i < p->files->max_fds; i++) {
				filp = fcheck_files(p->files, i);
				if (filp && (filp->f_op == &tty_fops) &&
				    (filp->private_data == tty)) {
					send_sig(SIGKILL, p, 1);
					break;
				}
			}
			read_unlock(&p->files->file_lock);
		}
		task_unlock(p);
	}
	read_unlock(&tasklist_lock);
#endif
}

/*
 * The tq handling here is a little racy - tty->SAK_tq may already be queued.
 * But there's no mechanism to fix that without futzing with tqueue_lock.
 * Fortunately we don't need to worry, because if ->SAK_tq is already queued,
 * the values which we write to it will be identical to the values which it
 * already has. --akpm
 */
void do_SAK(struct tty_struct *tty)
{
	if (!tty)
		return;
	PREPARE_TQUEUE(&tty->SAK_tq, __do_SAK, tty);
	schedule_task(&tty->SAK_tq);
}

/*
 * This routine is called out of the software interrupt to flush data
 * from the flip buffer to the line discipline.
 */
static void flush_to_ldisc(void *private_)
{
	struct tty_struct *tty = (struct tty_struct *) private_;
	unsigned char	*cp;
	char		*fp;
	int		count;
	unsigned long flags;

	if (test_bit(TTY_DONT_FLIP, &tty->flags)) {
		queue_task(&tty->flip.tqueue, &tq_timer);
		return;
	}
	if (tty->flip.buf_num) {
		cp = tty->flip.char_buf + TTY_FLIPBUF_SIZE;
		fp = tty->flip.flag_buf + TTY_FLIPBUF_SIZE;
		tty->flip.buf_num = 0;

		save_flags(flags); cli();
		tty->flip.char_buf_ptr = tty->flip.char_buf;
		tty->flip.flag_buf_ptr = tty->flip.flag_buf;
	} else {
		cp = tty->flip.char_buf;
		fp = tty->flip.flag_buf;
		tty->flip.buf_num = 1;

		save_flags(flags); cli();
		tty->flip.char_buf_ptr = tty->flip.char_buf + TTY_FLIPBUF_SIZE;
		tty->flip.flag_buf_ptr = tty->flip.flag_buf + TTY_FLIPBUF_SIZE;
	}
	count = tty->flip.count;
	tty->flip.count = 0;
	restore_flags(flags);
	
	tty->ldisc.receive_buf(tty, cp, fp, count);
}

/*
 * Routine which returns the baud rate of the tty
 *
 * Note that the baud_table needs to be kept in sync with the
 * include/asm/termbits.h file.
 */
static int baud_table[] = {
	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
	9600, 19200, 38400, 57600, 115200, 230400, 460800,
#ifdef __sparc__
	76800, 153600, 307200, 614400, 921600
#else
	500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000,
	2500000, 3000000, 3500000, 4000000
#endif
};

static int n_baud_table = sizeof(baud_table)/sizeof(int);

int tty_get_baud_rate(struct tty_struct *tty)
{
	unsigned int cflag, i;

	cflag = tty->termios->c_cflag;

	i = cflag & CBAUD;
	if (i & CBAUDEX) {
		i &= ~CBAUDEX;
		if (i < 1 || i+15 >= n_baud_table) 
			tty->termios->c_cflag &= ~CBAUDEX;
		else
			i += 15;
	}
	if (i==15 && tty->alt_speed) {
		if (!tty->warned) {
			printk(KERN_WARNING "Use of setserial/setrocket to "
					    "set SPD_* flags is deprecated\n");
			tty->warned = 1;
		}
		return(tty->alt_speed);
	}
	
	return baud_table[i];
}

void tty_flip_buffer_push(struct tty_struct *tty)
{
	if (tty->low_latency)
		flush_to_ldisc((void *) tty);
	else
		queue_task(&tty->flip.tqueue, &tq_timer);
}

/*
 * This subroutine initializes a tty structure.
 */
static void initialize_tty_struct(struct tty_struct *tty)
{
	memset(tty, 0, sizeof(struct tty_struct));
	tty->magic = TTY_MAGIC;
	tty->ldisc = ldiscs[N_TTY];
	tty->pgrp = -1;
	tty->flip.char_buf_ptr = tty->flip.char_buf;
	tty->flip.flag_buf_ptr = tty->flip.flag_buf;
	tty->flip.tqueue.routine = flush_to_ldisc;
	tty->flip.tqueue.data = tty;
	init_MUTEX(&tty->flip.pty_sem);
	init_waitqueue_head(&tty->write_wait);
	init_waitqueue_head(&tty->read_wait);
	tty->tq_hangup.routine = do_tty_hangup;
	tty->tq_hangup.data = tty;
	sema_init(&tty->atomic_read, 1);
	sema_init(&tty->atomic_write, 1);
	spin_lock_init(&tty->read_lock);
	INIT_LIST_HEAD(&tty->tty_files);
	INIT_TQUEUE(&tty->SAK_tq, 0, 0);
}

/*
 * The default put_char routine if the driver did not define one.
 */
void tty_default_put_char(struct tty_struct *tty, unsigned char ch)
{
	tty->driver.write(tty, 0, &ch, 1);
}

/*
 * Register a tty device described by <driver>, with minor number <minor>.
 */
void tty_register_devfs (struct tty_driver *driver, unsigned int flags, unsigned minor)
{
#ifdef CONFIG_DEVFS_FS
	umode_t mode = S_IFCHR | S_IRUSR | S_IWUSR;
	kdev_t device = MKDEV (driver->major, minor);
	int idx = minor - driver->minor_start;
	char buf[32];

	switch (device) {
		case TTY_DEV:
		case PTMX_DEV:
			mode |= S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
			break;
		default:
			if (driver->major == PTY_MASTER_MAJOR)
				mode |= S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
			break;
	}
	if ( (minor <  driver->minor_start) || 
	     (minor >= driver->minor_start + driver->num) ) {
		printk(KERN_ERR "Attempt to register invalid minor number "
		       "with devfs (%d:%d).\n", (int)driver->major,(int)minor);
		return;
	}
#  ifdef CONFIG_UNIX98_PTYS
	if ( (driver->major >= UNIX98_PTY_SLAVE_MAJOR) &&
	     (driver->major < UNIX98_PTY_SLAVE_MAJOR + UNIX98_NR_MAJORS) )
		flags |= DEVFS_FL_CURRENT_OWNER;
#  endif
	sprintf(buf, driver->name, idx + driver->name_base);
	devfs_register (NULL, buf, flags | DEVFS_FL_DEFAULT,
			driver->major, minor, mode, &tty_fops, NULL);
#endif /* CONFIG_DEVFS_FS */
}

void tty_unregister_devfs (struct tty_driver *driver, unsigned minor)
{
#ifdef CONFIG_DEVFS_FS
	void * handle;
	int idx = minor - driver->minor_start;
	char buf[32];

	sprintf(buf, driver->name, idx + driver->name_base);
	handle = devfs_find_handle (NULL, buf, driver->major, minor,
				    DEVFS_SPECIAL_CHR, 0);
	devfs_unregister (handle);
#endif /* CONFIG_DEVFS_FS */
}

EXPORT_SYMBOL(tty_register_devfs);
EXPORT_SYMBOL(tty_unregister_devfs);

/*
 * Called by a tty driver to register itself.
 */
int tty_register_driver(struct tty_driver *driver)
{
	int error;
        int i;

	if (driver->flags & TTY_DRIVER_INSTALLED)
		return 0;

	error = devfs_register_chrdev(driver->major, driver->name, &tty_fops);
	if (error < 0)
		return error;
	else if(driver->major == 0)
		driver->major = error;

	if (!driver->put_char)
		driver->put_char = tty_default_put_char;
	
	driver->prev = 0;
	driver->next = tty_drivers;
	if (tty_drivers) tty_drivers->prev = driver;
	tty_drivers = driver;
	
	if ( !(driver->flags & TTY_DRIVER_NO_DEVFS) ) {
		for(i = 0; i < driver->num; i++)
		    tty_register_devfs(driver, 0, driver->minor_start + i);
	}
	proc_tty_register_driver(driver);
	return error;
}

/*
 * Called by a tty driver to unregister itself.
 */
int tty_unregister_driver(struct tty_driver *driver)
{
	int	retval;
	struct tty_driver *p;
	int	i, found = 0;
	struct termios *tp;
	const char *othername = NULL;
	
	if (*driver->refcount)
		return -EBUSY;

	for (p = tty_drivers; p; p = p->next) {
		if (p == driver)
			found++;
		else if (p->major == driver->major)
			othername = p->name;
	}
	
	if (!found)
		return -ENOENT;

	if (othername == NULL) {
		retval = devfs_unregister_chrdev(driver->major, driver->name);
		if (retval)
			return retval;
	} else
		devfs_register_chrdev(driver->major, othername, &tty_fops);

	if (driver->prev)
		driver->prev->next = driver->next;
	else
		tty_drivers = driver->next;
	
	if (driver->next)
		driver->next->prev = driver->prev;

	/*
	 * Free the termios and termios_locked structures because
	 * we don't want to get memory leaks when modular tty
	 * drivers are removed from the kernel.
	 */
	for (i = 0; i < driver->num; i++) {
		tp = driver->termios[i];
		if (tp) {
			driver->termios[i] = NULL;
			kfree(tp);
		}
		tp = driver->termios_locked[i];
		if (tp) {
			driver->termios_locked[i] = NULL;
			kfree(tp);
		}
		tty_unregister_devfs(driver, driver->minor_start + i);
	}
	proc_tty_unregister_driver(driver);
	return 0;
}


/*
 * Initialize the console device. This is called *early*, so
 * we can't necessarily depend on lots of kernel help here.
 * Just do some early initializations, and do the complex setup
 * later.
 */
void __init console_init(void)
{
	/* Setup the default TTY line discipline. */
	memset(ldiscs, 0, sizeof(ldiscs));
	(void) tty_register_ldisc(N_TTY, &tty_ldisc_N_TTY);

	/*
	 * Set up the standard termios.  Individual tty drivers may 
	 * deviate from this; this is used as a template.
	 */
	memset(&tty_std_termios, 0, sizeof(struct termios));
	memcpy(tty_std_termios.c_cc, INIT_C_CC, NCCS);
	tty_std_termios.c_iflag = ICRNL | IXON;
	tty_std_termios.c_oflag = OPOST | ONLCR;
	tty_std_termios.c_cflag = B38400 | CS8 | CREAD | HUPCL;
	tty_std_termios.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
		ECHOCTL | ECHOKE | IEXTEN;

	/*
	 * set up the console device so that later boot sequences can 
	 * inform about problems etc..
	 */
#ifdef CONFIG_VT
	con_init();
#endif
#ifdef CONFIG_AU1000_SERIAL_CONSOLE
	au1000_serial_console_init();
#endif
#ifdef CONFIG_SERIAL_CONSOLE
#if (defined(CONFIG_8xx) || defined(CONFIG_8260))
	console_8xx_init();
#elif defined(CONFIG_MAC_SERIAL) && defined(CONFIG_SERIAL)
	if (_machine == _MACH_Pmac)
 		mac_scc_console_init();
	else
		serial_console_init();
#elif defined(CONFIG_MAC_SERIAL)
 	mac_scc_console_init();
#elif defined(CONFIG_PARISC)
	pdc_console_init();
#elif defined(CONFIG_SERIAL)
	serial_console_init();
#endif /* CONFIG_8xx */
#ifdef CONFIG_SGI_SERIAL
	sgi_serial_console_init();
#endif
#if defined(CONFIG_MVME162_SCC) || defined(CONFIG_BVME6000_SCC) || defined(CONFIG_MVME147_SCC)
	vme_scc_console_init();
#endif
#if defined(CONFIG_SERIAL167)
	serial167_console_init();
#endif
#if defined(CONFIG_SH_SCI)
	sci_console_init();
#endif
#endif
#ifdef CONFIG_TN3270_CONSOLE
	tub3270_con_init();
#endif
#ifdef CONFIG_TN3215
	con3215_init();
#endif
#ifdef CONFIG_HWC
        hwc_console_init();
#endif
#ifdef CONFIG_STDIO_CONSOLE
	stdio_console_init();
#endif
#ifdef CONFIG_SERIAL_CORE_CONSOLE
	uart_console_init();
#endif
#ifdef CONFIG_ARC_CONSOLE
	arc_console_init();
#endif
#ifdef CONFIG_SERIAL_TX3912_CONSOLE
	tx3912_console_init();
#endif
#ifdef CONFIG_TXX927_SERIAL_CONSOLE
	txx927_console_init();
#endif
#ifdef CONFIG_SIBYTE_SB1250_DUART_CONSOLE
	sb1250_serial_console_init();
#endif
}

static struct tty_driver dev_tty_driver, dev_syscons_driver;
#ifdef CONFIG_UNIX98_PTYS
static struct tty_driver dev_ptmx_driver;
#endif
#ifdef CONFIG_VT
static struct tty_driver dev_console_driver;
#endif

/*
 * Ok, now we can initialize the rest of the tty devices and can count
 * on memory allocations, interrupts etc..
 */
void __init tty_init(void)
{
	/*
	 * dev_tty_driver and dev_console_driver are actually magic
	 * devices which get redirected at open time.  Nevertheless,
	 * we register them so that register_chrdev is called
	 * appropriately.
	 */
	memset(&dev_tty_driver, 0, sizeof(struct tty_driver));
	dev_tty_driver.magic = TTY_DRIVER_MAGIC;
	dev_tty_driver.driver_name = "/dev/tty";
	dev_tty_driver.name = dev_tty_driver.driver_name + 5;
	dev_tty_driver.name_base = 0;
	dev_tty_driver.major = TTYAUX_MAJOR;
	dev_tty_driver.minor_start = 0;
	dev_tty_driver.num = 1;
	dev_tty_driver.type = TTY_DRIVER_TYPE_SYSTEM;
	dev_tty_driver.subtype = SYSTEM_TYPE_TTY;
	
	if (tty_register_driver(&dev_tty_driver))
		panic("Couldn't register /dev/tty driver\n");

	dev_syscons_driver = dev_tty_driver;
	dev_syscons_driver.driver_name = "/dev/console";
	dev_syscons_driver.name = dev_syscons_driver.driver_name + 5;
	dev_syscons_driver.major = TTYAUX_MAJOR;
	dev_syscons_driver.minor_start = 1;
	dev_syscons_driver.type = TTY_DRIVER_TYPE_SYSTEM;
	dev_syscons_driver.subtype = SYSTEM_TYPE_SYSCONS;

	if (tty_register_driver(&dev_syscons_driver))
		panic("Couldn't register /dev/console driver\n");

	/* console calls tty_register_driver() before kmalloc() works.
	 * Thus, we can't devfs_register() then.  Do so now, instead. 
	 */
#ifdef CONFIG_VT
	con_init_devfs();
#endif

#ifdef CONFIG_UNIX98_PTYS
	dev_ptmx_driver = dev_tty_driver;
	dev_ptmx_driver.driver_name = "/dev/ptmx";
	dev_ptmx_driver.name = dev_ptmx_driver.driver_name + 5;
	dev_ptmx_driver.major= MAJOR(PTMX_DEV);
	dev_ptmx_driver.minor_start = MINOR(PTMX_DEV);
	dev_ptmx_driver.type = TTY_DRIVER_TYPE_SYSTEM;
	dev_ptmx_driver.subtype = SYSTEM_TYPE_SYSPTMX;

	if (tty_register_driver(&dev_ptmx_driver))
		panic("Couldn't register /dev/ptmx driver\n");
#endif
	
#ifdef CONFIG_VT
	dev_console_driver = dev_tty_driver;
	dev_console_driver.driver_name = "/dev/vc/0";
	dev_console_driver.name = dev_console_driver.driver_name + 5;
	dev_console_driver.major = TTY_MAJOR;
	dev_console_driver.type = TTY_DRIVER_TYPE_SYSTEM;
	dev_console_driver.subtype = SYSTEM_TYPE_CONSOLE;

	if (tty_register_driver(&dev_console_driver))
		panic("Couldn't register /dev/tty0 driver\n");

	kbd_init();
#endif

#ifdef CONFIG_ESPSERIAL  /* init ESP before rs, so rs doesn't see the port */
	espserial_init();
#endif
#if defined(CONFIG_MVME162_SCC) || defined(CONFIG_BVME6000_SCC) || defined(CONFIG_MVME147_SCC)
	vme_scc_init();
#endif
#ifdef CONFIG_SERIAL_TX3912
	tx3912_rs_init();
#endif
#ifdef CONFIG_ROCKETPORT
	rp_init();
#endif
#ifdef CONFIG_SERIAL167
	serial167_init();
#endif
#ifdef CONFIG_CYCLADES
	cy_init();
#endif
#ifdef CONFIG_STALLION
	stl_init();
#endif
#ifdef CONFIG_ISTALLION
	stli_init();
#endif
#ifdef CONFIG_DIGI
	pcxe_init();
#endif
#ifdef CONFIG_DIGIEPCA
	pc_init();
#endif
#ifdef CONFIG_SPECIALIX
	specialix_init();
#endif
#if (defined(CONFIG_8xx) || defined(CONFIG_8260))
	rs_8xx_init();
#endif /* CONFIG_8xx */
	pty_init();
#ifdef CONFIG_MOXA_SMARTIO
	mxser_init();
#endif	
#ifdef CONFIG_MOXA_INTELLIO
	moxa_init();
#endif	
#ifdef CONFIG_VT
	vcs_init();
#endif
#ifdef CONFIG_TN3270
	tub3270_init();
#endif
#ifdef CONFIG_TN3215
	tty3215_init();
#endif
#ifdef CONFIG_HWC
	hwc_tty_init();
#endif
#ifdef CONFIG_A2232
	a2232board_init();
#endif
}