dz.c

讲述linux的初始化过程

  if (--info->count < 0) {
    printk("ds_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 |= DZ_CLOSING;
  /*
   * Save the termios structure, since this port may have
   * separate termios for callout and dialin.
   */
  if (info->flags & DZ_NORMAL_ACTIVE)
    info->normal_termios = *tty->termios;
  if (info->flags & DZ_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 != DZ_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.
   */

  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 (tty->ldisc.num != ldiscs[N_TTY].num) {
    if (tty->ldisc.close)
      (tty->ldisc.close)(tty);
    tty->ldisc = ldiscs[N_TTY];
    tty->termios->c_line = N_TTY;
    if (tty->ldisc.open)
      (tty->ldisc.open)(tty);
  }
  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 &= ~(DZ_NORMAL_ACTIVE | DZ_CALLOUT_ACTIVE | DZ_CLOSING);
  wake_up_interruptible (&info->close_wait);

  restore_flags (flags);
}

/*
 * dz_hangup () --- called by tty_hangup() when a hangup is signaled.
 */
static void dz_hangup (struct tty_struct *tty)
{
  struct dz_serial *info = (struct dz_serial *)tty->driver_data;
  
  dz_flush_buffer (tty);
  shutdown (info);
  info->event = 0;
  info->count = 0;
  info->flags &= ~(DZ_NORMAL_ACTIVE | DZ_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 dz_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 & DZ_CLOSING) {
    interruptible_sleep_on (&info->close_wait);
    return -EAGAIN;
  }

  /*
   * 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 & DZ_NORMAL_ACTIVE)
      return -EBUSY;
    
    if ((info->flags & DZ_CALLOUT_ACTIVE) &&
	(info->flags & DZ_SESSION_LOCKOUT) &&
	(info->session != current->session))
      return -EBUSY;
    
    if ((info->flags & DZ_CALLOUT_ACTIVE) &&
	(info->flags & DZ_PGRP_LOCKOUT) &&
	(info->pgrp != current->pgrp))
      return -EBUSY;
    info->flags |= DZ_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 & DZ_CALLOUT_ACTIVE)
      return -EBUSY;
    info->flags |= DZ_NORMAL_ACTIVE;
    return 0;
  }

  if (info->flags & DZ_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
   * dz_close() knows when to free things.  We restore it upon
   * exit, either normal or abnormal.
   */
  retval = 0;
  add_wait_queue (&info->open_wait, &wait);

  info->count--;
  info->blocked_open++;
  while (1) {
    set_current_state(TASK_INTERRUPTIBLE);
    if (tty_hung_up_p (filp) || !(info->is_initialized)) {
      retval = -EAGAIN;
      break;
    }
    if (!(info->flags & DZ_CALLOUT_ACTIVE) &&
	!(info->flags & DZ_CLOSING) && do_clocal)
      break;
    if (signal_pending (current)) {
      retval = -ERESTARTSYS;
      break;
    }
    schedule();
  }
		
  current->state = TASK_RUNNING;
  remove_wait_queue (&info->open_wait, &wait);
  if (!tty_hung_up_p(filp))
    info->count++;
  info->blocked_open--;

  if (retval)
    return retval;
  info->flags |= DZ_NORMAL_ACTIVE;
  return 0;
}       

/*
 * This routine is called whenever a serial port is opened.  It
 * enables interrupts for a serial port. It also performs the 
 * serial-specific initialization for the tty structure.
 */
static int dz_open (struct tty_struct *tty, struct file *filp)
{
  struct dz_serial *info;
  int retval, line;

  line = MINOR(tty->device) - tty->driver.minor_start;

  /* The dz lines for the mouse/keyboard must be
   * opened using their respective drivers.
   */
  if ((line < 0) || (line >= DZ_NB_PORT))
    return -ENODEV;

  if ((line == DZ_KEYBOARD) || (line == DZ_MOUSE))
    return -ENODEV;

  info = lines[line];
  info->count++;

  tty->driver_data = info;
  info->tty = tty;

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



  retval = block_til_ready (tty, filp, info);
  if (retval)
    return retval;

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

  }

  info->session = current->session;
  info->pgrp = current->pgrp;
  return 0;
}

static void show_serial_version (void)
{
  printk("%s%s\n", dz_name, dz_version);
}


int __init dz_init(void)
{
  int i, flags;
  struct dz_serial *info;

  /* Setup base handler, and timer table. */
  init_bh (SERIAL_BH, do_serial_bh);

  show_serial_version ();

  memset(&serial_driver, 0, sizeof(struct tty_driver));
  serial_driver.magic = TTY_DRIVER_MAGIC;
  serial_driver.name = "ttyS";
  serial_driver.major = TTY_MAJOR;
  serial_driver.minor_start = 64;
  serial_driver.num = DZ_NB_PORT;
  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 = dz_open;
  serial_driver.close = dz_close;
  serial_driver.write = dz_write;
  serial_driver.flush_chars = dz_flush_chars;
  serial_driver.write_room = dz_write_room;
  serial_driver.chars_in_buffer = dz_chars_in_buffer;
  serial_driver.flush_buffer = dz_flush_buffer;
  serial_driver.ioctl = dz_ioctl;
  serial_driver.throttle = dz_throttle;
  serial_driver.unthrottle = dz_unthrottle;
  serial_driver.send_xchar = dz_send_xchar;
  serial_driver.set_termios = dz_set_termios;
  serial_driver.stop = dz_stop;
  serial_driver.start = dz_start;
  serial_driver.hangup = dz_hangup;

  /*
   * 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;

  if (tty_register_driver (&serial_driver))
    panic("Couldn't register serial driver\n");
  if (tty_register_driver (&callout_driver))
    panic("Couldn't register callout driver\n");
  save_flags(flags); cli();
 
  for (i=0; i < DZ_NB_PORT;  i++)  
    {
      info = &multi[i]; 
      lines[i] = info;
    info->magic = SERIAL_MAGIC;

      if ((mips_machtype == MACH_DS23100) || (mips_machtype == MACH_DS5100)) 
      info->port = (unsigned long) KN01_DZ11_BASE;
      else 
      info->port = (unsigned long) KN02_DZ11_BASE;

    info->line = i;
    info->tty = 0;
    info->close_delay = 50;
    info->closing_wait = 3000;
    info->x_char = 0;
    info->event = 0;
    info->count = 0;
    info->blocked_open = 0;
    info->tqueue.routine = do_softint;
    info->tqueue.data = info;
    info->tqueue_hangup.routine = do_serial_hangup;
    info->tqueue_hangup.data = info;
    info->callout_termios = callout_driver.init_termios;
    info->normal_termios = serial_driver.init_termios;
    init_waitqueue_head(&info->open_wait); 
    init_waitqueue_head(&info->close_wait); 

    /* If we are pointing to address zero then punt - not correctly
       set up in setup.c to handle this. */
    if (! info->port)
      return 0;

    printk("ttyS%02d at 0x%04x (irq = %d)\n", info->line, info->port, SERIAL);
  }

  /* reset the chip */
#ifndef CONFIG_SERIAL_CONSOLE
  dz_out(info, DZ_CSR, DZ_CLR);
  while ((tmp = dz_in(info,DZ_CSR)) & DZ_CLR) ;
  wbflush();
  
  /* enable scanning */
   dz_out(info, DZ_CSR, DZ_MSE); 
#endif
  
  /* order matters here... the trick is that flags
     is updated... in request_irq - to immediatedly obliterate
     it is unwise. */
  restore_flags(flags);
 

  if (request_irq (SERIAL, dz_interrupt, SA_INTERRUPT, "DZ", lines[0]))
    panic ("Unable to register DZ interrupt\n");
 
  return 0;
}

#ifdef CONFIG_SERIAL_CONSOLE
static void dz_console_put_char (unsigned char ch)
{
  unsigned long flags;
  int  loops = 2500;
  unsigned short tmp = ch;
  /* this code sends stuff out to serial device - spinning its
      wheels and waiting. */

  /* force the issue - point it at lines[3]*/
  dz_console=&multi[CONSOLE_LINE];

  save_flags(flags);
  cli();
  

  /* spin our wheels */
  while (((dz_in(dz_console,DZ_CSR) & DZ_TRDY) != DZ_TRDY) &&  loops--)
    ;
  
  /* Actually transmit the character. */
  dz_out (dz_console, DZ_TDR, tmp);

  restore_flags(flags); 
}
/* 
 * -------------------------------------------------------------------
 * dz_console_print ()
 *
 * dz_console_print is registered for printk.
 * The console_lock must be held when we get here.
 * ------------------------------------------------------------------- 
 */
static void dz_console_print (struct console *cons, 
			      const char *str, 
			      unsigned int count)
{
#ifdef DEBUG_DZ
  prom_printf((char *)str);
#endif
  while (count--) 
    {
    if (*str == '\n')
	dz_console_put_char ('\r');
      dz_console_put_char (*str++);
  }
}

static int dz_console_wait_key(struct console *co)
{
    return 0;
}

static kdev_t dz_console_device(struct console *c)
{
	return MKDEV(TTY_MAJOR, 64 + c->index);
}

static int __init dz_console_setup(struct console *co, char *options)
{
  	int	baud = 9600;
	int	bits = 8;
	int	parity = 'n';
	int	cflag = CREAD | HUPCL | CLOCAL;
	char	*s;
	unsigned short mask,tmp;

	if (options) {
		baud = simple_strtoul(options, NULL, 10);
		s = options;
		while(*s >= '0' && *s <= '9')
			s++;
		if (*s)
			parity = *s++;
		if (*s)
			bits   = *s - '0';
	}

	/*
	 *	Now construct a cflag setting.
	 */
	switch(baud) {
	case 1200:
		cflag |= DZ_B1200;
		break;
	case 2400:
		cflag |= DZ_B2400;
		break;
	case 4800:
		cflag |= DZ_B4800;
		break;
	case 9600:
	default:
		cflag |= DZ_B9600;
		break;
	}
	switch(bits) {
	case 7:
		cflag |= DZ_CS7;
		break;
	default:
	case 8:
		cflag |= DZ_CS8;
		break;
	}
	switch(parity) {
	case 'o': case 'O':
		cflag |= DZ_PARODD;
		break;
	case 'e': case 'E':
		cflag |= DZ_PARENB;
		break;
	}
	co->cflag = cflag;

	/* TOFIX: force to console line */
	dz_console = &multi[CONSOLE_LINE];
    	if ((mips_machtype == MACH_DS23100) || (mips_machtype == MACH_DS5100)) 
	dz_console->port = KN01_DZ11_BASE;
       	else 
       		dz_console->port = KN02_DZ11_BASE; 
	dz_console->line = CONSOLE_LINE;

	dz_out(dz_console, DZ_CSR, DZ_CLR);
	while ((tmp = dz_in(dz_console,DZ_CSR)) & DZ_CLR)
	  ;

	/* enable scanning */
	dz_out(dz_console, DZ_CSR, DZ_MSE); 

        /*  Set up flags... */
	dz_console->cflags = 0;
	dz_console->cflags |= DZ_B9600;
	dz_console->cflags |= DZ_CS8;
	dz_console->cflags |= DZ_PARENB;
	dz_out (dz_console, DZ_LPR, dz_console->cflags);

	mask = 1 << dz_console->line;
	tmp = dz_in (dz_console, DZ_TCR);       /* read the TX flag */
	if (!(tmp & mask)) {
	  tmp |= mask;                   /* set the TX flag */
	  dz_out (dz_console, DZ_TCR, tmp); 
	}
	

	return 0;
}

static struct console dz_sercons = {
	name:		"ttyS",
	write:		dz_console_print,
	device:		dz_console_device,
	wait_key:	dz_console_wait_key,
	setup:		dz_console_setup,
	flags:		CON_CONSDEV | CON_PRINTBUFFER,
	index:		CONSOLE_LINE,
};

void __init dz_serial_console_init(void)
{
	register_console(&dz_sercons);
}

#endif /* ifdef CONFIG_SERIAL_CONSOLE */