/*
 * dz.c: Serial port driver for DECStations equiped 
 *       with the DZ chipset.
 *
 * Copyright (C) 1998 Olivier A. D. Lebaillif 
 *             
 * Email: olivier.lebaillif@ifrsys.com
 *
 * [31-AUG-98] triemer
 * Changed IRQ to use Harald's dec internals interrupts.h
 * removed base_addr code - moving address assignment to setup.c
 * Changed name of dz_init to rs_init to be consistent with tc code
 * [13-NOV-98] triemer fixed code to receive characters
 *    after patches by harald to irq code.  
 * [09-JAN-99] triemer minor fix for schedule - due to removal of timeout
 *            field from "current" - somewhere between 2.1.121 and 2.1.131
 *  
 * Parts (C) 1999 David Airlie, airlied@linux.ie 
 * [07-SEP-99] Bugfixes 
 */

#define DEBUG_DZ 1

#ifdef MODULE
#include <linux/module.h>
#include <linux/version.h>
#else
#define MOD_INC_USE_COUNT
#define MOD_DEC_USE_COUNT
#endif

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h> 
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/major.h>
#include <linux/param.h>
#include <linux/tqueue.h>
#include <linux/interrupt.h>
#include <asm-mips/wbflush.h>
/* for definition of SERIAL */
#include <asm/dec/interrupts.h>

/* for definition of struct console */
#ifdef CONFIG_SERIAL_CONSOLE
#define CONSOLE_LINE (3)
#endif /* ifdef CONFIG_SERIAL_CONSOLE */
#if defined(CONFIG_SERIAL_CONSOLE) || defined(DEBUG_DZ)
#include <linux/console.h>
#endif /* if defined(CONFIG_SERIAL_CONSOLE) || defined(DEBUG_DZ) */

#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>

#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/dec/machtype.h>
#include <asm/dec/kn01.h>
#include <asm/dec/kn02.h>

#ifdef DEBUG_DZ
#include <linux/ptrace.h>
#include <linux/fs.h>
#include <asm/bootinfo.h>

extern int (*prom_printf) (char *,...);
#endif



#include "dz.h"

#define DZ_INTR_DEBUG 1

DECLARE_TASK_QUEUE(tq_serial);

extern wait_queue_head_t keypress_wait; 
static struct dz_serial *lines[4];
static unsigned char tmp_buffer[256];



#ifdef DEBUG_DZ
/*
 * debugging code to send out chars via prom 
 */
static void debug_console( const char *s,int count)
{
    unsigned i;

    for (i = 0; i < count; i++) {
       if (*s == 10)
           prom_printf("%c", 13);
       prom_printf("%c", *s++);
    }
}
#endif

/*
 * ------------------------------------------------------------
 * dz_in () and dz_out ()
 *
 * These routines are used to access the registers of the DZ 
 * chip, hiding relocation differences between implementation.
 * ------------------------------------------------------------
 */

static inline unsigned short dz_in (struct dz_serial *info, unsigned offset)
{
  volatile unsigned short *addr = (volatile unsigned short *)(info->port + offset);
  return *addr;
}

static inline void dz_out (struct dz_serial *info, unsigned offset, unsigned short value)
{

    volatile unsigned short *addr = (volatile unsigned short *)(info->port + offset);
  *addr = value;

}

/*
 * ------------------------------------------------------------
 * rs_stop () and rs_start ()
 *
 * These routines are called before setting or resetting 
 * tty->stopped. They enable or disable transmitter interrupts, 
 * as necessary.
 * ------------------------------------------------------------
 */

static void dz_stop (struct tty_struct *tty)
{
  struct dz_serial *info; 
  unsigned short mask, tmp;

  if (tty==0) 
    return; 
 
  info = (struct dz_serial *)tty->driver_data; 
         
  mask = 1 << info->line;
  tmp = dz_in (info, DZ_TCR);       /* read the TX flag */

    tmp &= ~mask;                   /* clear the TX flag */
    dz_out (info, DZ_TCR, tmp);
}  

static void dz_start (struct tty_struct *tty)
{
  struct dz_serial *info = (struct dz_serial *)tty->driver_data;
  unsigned short mask, tmp;

  mask = 1 << info->line;
  tmp = dz_in (info, DZ_TCR);      /* read the TX flag */

    tmp |= mask;                   /* set the TX flag */
    dz_out (info, DZ_TCR, tmp);

}  

/*
 * ------------------------------------------------------------
 * Here starts the interrupt handling routines.  All of the 
 * following subroutines are declared as inline and are folded 
 * into dz_interrupt.  They were separated out for readability's 
 * sake. 
 *
 * Note: rs_interrupt() is a "fast" interrupt, which means that it
 * runs with interrupts turned off.  People who may want to modify
 * rs_interrupt() should try to keep the interrupt handler as fast as
 * possible.  After you are done making modifications, it is not a bad
 * idea to do:
 * 
 * gcc -S -DKERNEL -Wall -Wstrict-prototypes -O6 -fomit-frame-pointer dz.c
 *
 * and look at the resulting assemble code in serial.s.
 *
 * ------------------------------------------------------------
 */

/*
 * ------------------------------------------------------------
 * dz_sched_event ()
 *
 * This routine is used by the interrupt handler to schedule
 * processing in the software interrupt portion of the driver.
 * ------------------------------------------------------------
 */
static inline void dz_sched_event (struct dz_serial *info, int event)
{
  info->event |= 1 << event;
  queue_task (&info->tqueue, &tq_serial);
  mark_bh (SERIAL_BH);
}

/*
 * ------------------------------------------------------------
 * receive_char ()
 *
 * This routine deals with inputs from any lines.
 * ------------------------------------------------------------
 */
static inline void receive_chars (struct dz_serial *info_in)
{

  struct dz_serial *info;
  struct tty_struct *tty = 0;
  struct async_icount *icount;
  int ignore = 0;
  unsigned short status, tmp;
  unsigned char ch;

  /* this code is going to be a problem...
     the call to tty_flip_buffer is going to need
     to be rethought...
   */
  do
    {
      status = dz_in (info_in, DZ_RBUF);
      info = lines[LINE(status)];

      /* punt so we don't get duplicate characters */
      if (!(status & DZ_DVAL))
        goto ignore_char;


    ch = UCHAR(status);                /* grab the char */

#if 0
    if (info->is_console) {
      if (ch == 0) return;            /* it's a break ... */

      wake_up (&keypress_wait);       /* It is a 'keyboard interrupt' ;-) */
    }
#endif

    tty = info->tty;                  /* now tty points to the proper dev */
    icount = &info->icount;

    if (!tty) break;
    if (tty->flip.count >= TTY_FLIPBUF_SIZE) break;

    *tty->flip.char_buf_ptr = ch;
    *tty->flip.flag_buf_ptr = 0;
    icount->rx++;

    /* keep track of the statistics */
    if (status & (DZ_OERR | DZ_FERR | DZ_PERR)) {
      if (status & DZ_PERR)                /* parity error */
        icount->parity++;
      else if (status & DZ_FERR)           /* frame error */
        icount->frame++;
      if (status & DZ_OERR)                /* overrun error */
        icount->overrun++;

      /*  check to see if we should ignore the character
	 and mask off conditions that should be ignored
      */

      if (status & info->ignore_status_mask) {
        if (++ignore > 100 ) break;
        goto ignore_char;
      }

      /* mask off the error conditions we want to ignore */
      tmp = status & info->read_status_mask;

      if (tmp & DZ_PERR)
	{
        *tty->flip.flag_buf_ptr = TTY_PARITY;
	  debug_console("PERR\n",5);
	}
      else if (tmp & DZ_FERR)
	{
        *tty->flip.flag_buf_ptr = TTY_FRAME;
	  debug_console("FERR\n",5);
	}
      if (tmp & DZ_OERR) 
	{ 
	  debug_console("OERR\n",5);
	if (tty->flip.count < TTY_FLIPBUF_SIZE) {
          tty->flip.count++;
          tty->flip.flag_buf_ptr++;
          tty->flip.char_buf_ptr++;
          *tty->flip.flag_buf_ptr = TTY_OVERRUN;
        }
      }
    }
    tty->flip.flag_buf_ptr++;
    tty->flip.char_buf_ptr++;
    tty->flip.count++;
  ignore_char:
  } while (status & DZ_DVAL);

  if (tty)
    tty_flip_buffer_push(tty);
}

/*
 * ------------------------------------------------------------
 * transmit_char ()
 *
 * This routine deals with outputs to any lines.
 * ------------------------------------------------------------
 */
static inline void transmit_chars (struct dz_serial *info)
{
  unsigned char tmp;



  if (info->x_char) {           /* XON/XOFF chars */
    dz_out (info, DZ_TDR, info->x_char);
    info->icount.tx++;
    info->x_char = 0;
    return;
  }

  /* if nothing to do or stopped or hardware stopped */
  if ((info->xmit_cnt <= 0) || info->tty->stopped || info->tty->hw_stopped) {
    dz_stop (info->tty);
    return;
  }

  /* if something to do ... (rember the dz has no output fifo so we go one char at a time :-< */
  tmp = (unsigned short)info->xmit_buf[info->xmit_tail++];
  dz_out (info, DZ_TDR, tmp);
  info->xmit_tail = info->xmit_tail & (DZ_XMIT_SIZE - 1);
  info->icount.tx++;

  if (--info->xmit_cnt < WAKEUP_CHARS)
    dz_sched_event (info, DZ_EVENT_WRITE_WAKEUP);


  /* Are we done */
  if (info->xmit_cnt <= 0) dz_stop (info->tty);
}

/*
 * ------------------------------------------------------------
 * check_modem_status ()
 *
 * Only valid for the MODEM line duh !
 * ------------------------------------------------------------
 */
static inline void check_modem_status (struct dz_serial *info)
{
  unsigned short status;

  /* if not ne modem line just return */
  if (info->line != DZ_MODEM) return;

  status = dz_in (info, DZ_MSR);
  
  /* it's easy, since DSR2 is the only bit in the register */
  if (status) info->icount.dsr++;
}

/*
 * ------------------------------------------------------------
 * dz_interrupt ()
 *
 * this is the main interrupt routine for the DZ chip.
 * It deals with the multiple ports.
 * ------------------------------------------------------------
 */
static void dz_interrupt (int irq, void *dev, struct pt_regs *regs)
{
  struct dz_serial *info;
  unsigned short status;

  status = dz_in ((struct dz_serial *)dev, DZ_CSR); /* get the reason why we just got an irq */
  info = lines[LINE(status)];     /* re-arrange info the proper port */

  if (status & DZ_RDONE) 
      receive_chars (info);          /* the receive function */

  if (status & DZ_TRDY) 
    transmit_chars (info);
}

/*
 * -------------------------------------------------------------------
 * Here ends the DZ interrupt routines.
 * -------------------------------------------------------------------
 */

/*
 * This routine is used to handle the "bottom half" processing for the
 * serial driver, known also the "software interrupt" processing.
 * This processing is done at the kernel interrupt level, after the
 * rs_interrupt() has returned, BUT WITH INTERRUPTS TURNED ON.  This
 * is where time-consuming activities which can not be done in the
 * interrupt driver proper are done; the interrupt driver schedules
 * them using rs_sched_event(), and they get done here.
 */
static void do_serial_bh (void)
{
        run_task_queue (&tq_serial);
}

static void do_softint (void *private_data)
{
  struct dz_serial *info = (struct dz_serial *)private_data;
  struct tty_struct *tty = info->tty;

  if (!tty) return;

  if (test_and_clear_bit (DZ_EVENT_WRITE_WAKEUP, &info->event)) {
    if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) && tty->ldisc.write_wakeup)
      (tty->ldisc.write_wakeup) (tty);
    wake_up_interruptible (&tty->write_wait);
  }
}

/*
 * -------------------------------------------------------------------
 * This routine is called from the scheduler tqueue when the interrupt
 * routine has signalled that a hangup has occurred.  The path of
 * hangup processing is:
 *
 *      serial interrupt routine -> (scheduler tqueue) ->
 *      do_serial_hangup() -> tty->hangup() -> rs_hangup()
 * ------------------------------------------------------------------- 
 */
static void do_serial_hangup (void *private_data)
{
  struct dz_serial *info = (struct dz_serial *)private_data;
  struct tty_struct *tty = info->tty;;
        
  if (!tty) return;

  tty_hangup (tty);
}

/*
 * -------------------------------------------------------------------
 * startup ()
 *
 * various initialization tasks
 * ------------------------------------------------------------------- 
 */
static int startup (struct dz_serial *info)
{
  unsigned long page, flags;
  unsigned short tmp;

  if (info->is_initialized) return 0;
  
  save_flags (flags);
  cli ();

  if (!info->port) {
    if (info->tty) set_bit (TTY_IO_ERROR, &info->tty->flags);
    restore_flags (flags);
    return -ENODEV;
  }

  if (!info->xmit_buf) {
    page = get_free_page (GFP_KERNEL);
    if (!page) {
      restore_flags (flags);
      return -ENOMEM;
    }
    info->xmit_buf = (unsigned char *)page;
  }

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

  /* enable the interrupt and the scanning */
  tmp = dz_in (info, DZ_CSR);
  tmp |= (DZ_RIE | DZ_TIE | DZ_MSE);
  dz_out (info, DZ_CSR, tmp);

  info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;

  /* set up the speed */
  change_speed (info);

  /* clear the line transmitter buffer 
     I can't figure out why I need to do this - but
     its necessary - in order for the console portion
     and the interrupt portion to live happily side by side.
  */

  /* clear the line transmitter buffer 
     I can't figure out why I need to do this - but
     its necessary - in order for the console portion
     and the interrupt portion to live happily side by side.
  */

  info->is_initialized = 1;

  restore_flags (flags);
  return 0;
}

/* 
 * -------------------------------------------------------------------
 * shutdown ()
 *
 * This routine will shutdown a serial port; interrupts are disabled, and
 * DTR is dropped if the hangup on close termio flag is on.
 * ------------------------------------------------------------------- 
 */
static void shutdown (struct dz_serial *info)
{
  unsigned long flags;
  unsigned short tmp;

  if (!info->is_initialized) return;

  save_flags (flags);
  cli ();

  dz_stop (info->tty);



  info->cflags &= ~DZ_CREAD;          /* turn off receive enable flag */
  dz_out (info, DZ_LPR, info->cflags);

  if (info->xmit_buf) {               /* free Tx buffer */
    free_page ((unsigned long)info->xmit_buf);
    info->xmit_buf = 0;
  }

  if (!info->tty || (info->tty->termios->c_cflag & HUPCL)) {
    tmp = dz_in (info, DZ_TCR);
    if (tmp & DZ_MODEM_DTR) {
      tmp &= ~DZ_MODEM_DTR;
      dz_out (info, DZ_TCR, tmp);
    }
  }

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

  info->is_initialized = 0;
  restore_flags (flags);
}

/* 
 * -------------------------------------------------------------------
 * change_speed ()
 *
 * set the baud rate.
 * ------------------------------------------------------------------- 
 */
static void change_speed (struct dz_serial *info)
{
  unsigned long flags;
  unsigned cflag;
  int baud;

  if (!info->tty || !info->tty->termios) return;
  
  save_flags (flags);
  cli ();
  
  info->cflags = info->line;

  cflag = info->tty->termios->c_cflag;

  switch (cflag & CSIZE) {
  case CS5: info->cflags |= DZ_CS5; break;
  case CS6: info->cflags |= DZ_CS6; break;
  case CS7: info->cflags |= DZ_CS7; break;
  case CS8: 
  default:  info->cflags |= DZ_CS8;
  }

  if (cflag & CSTOPB) info->cflags |= DZ_CSTOPB;
  if (cflag & PARENB) info->cflags |= DZ_PARENB;
  if (cflag & PARODD) info->cflags |= DZ_PARODD;
  
  baud = tty_get_baud_rate (info->tty);
  switch (baud) {
  case 50  :  info->cflags |= DZ_B50;   break;
  case 75  :  info->cflags |= DZ_B75;   break;
  case 110 :  info->cflags |= DZ_B110;  break;
  case 134 :  info->cflags |= DZ_B134;  break; 
  case 150 :  info->cflags |= DZ_B150;  break;
  case 300 :  info->cflags |= DZ_B300;  break; 
  case 600 :  info->cflags |= DZ_B600;  break;
  case 1200:  info->cflags |= DZ_B1200; break; 
  case 1800:  info->cflags |= DZ_B1800; break;
  case 2000:  info->cflags |= DZ_B2000; break;
  case 2400:  info->cflags |= DZ_B2400; break;
  case 3600:  info->cflags |= DZ_B3600; break; 
  case 4800:  info->cflags |= DZ_B4800; break;
  case 7200:  info->cflags |= DZ_B7200; break; 
  case 9600: 
  default  :  info->cflags |= DZ_B9600; 
  }

  info->cflags |= DZ_RXENAB;
  dz_out (info, DZ_LPR, info->cflags);

  /* setup accept flag */
  info->read_status_mask = DZ_OERR;
  if (I_INPCK(info->tty))
   info->read_status_mask |= (DZ_FERR | DZ_PERR); 
  
  /* characters to ignore */
  info->ignore_status_mask = 0;
  if (I_IGNPAR(info->tty))
    info->ignore_status_mask |= (DZ_FERR | DZ_PERR);

  restore_flags (flags);
}

/* 
 * -------------------------------------------------------------------
 * dz_flush_char ()
 *
 * Flush the buffer.
 * ------------------------------------------------------------------- 
 */
static void dz_flush_chars (struct tty_struct *tty)
{
  struct dz_serial *info = (struct dz_serial *)tty->driver_data;
  unsigned long flags;

 if (info->xmit_cnt <= 0 || tty->stopped || tty->hw_stopped || !info->xmit_buf)
    return;

 save_flags (flags);
 cli ();  

 dz_start (info->tty);

 restore_flags (flags);
}


/* 
 * -------------------------------------------------------------------
 * dz_write ()
 *
 * main output routine.
 * ------------------------------------------------------------------- 
 */
static int dz_write (struct tty_struct *tty, int from_user, const unsigned char *buf, int count)
{
  struct dz_serial *info = (struct dz_serial *)tty->driver_data;
  unsigned long flags;
  int c, ret = 0;

  if (!tty ) return ret;
  if (!info->xmit_buf) return ret;
  if (!tmp_buf) tmp_buf = tmp_buffer;



  if (from_user) {

    down (&tmp_buf_sem);
    while (1) {
      c = MIN(count, MIN(DZ_XMIT_SIZE - info->xmit_cnt - 1, DZ_XMIT_SIZE - info->xmit_head));
      if (c <= 0) break;

      c -= copy_from_user (tmp_buf, buf, c);
      if (!c) {
        if (!ret) ret = -EFAULT;
        break;
      }

      save_flags (flags);
      cli ();

      c = MIN(c, MIN(DZ_XMIT_SIZE - info->xmit_cnt - 1, DZ_XMIT_SIZE - info->xmit_head));
      memcpy(info->xmit_buf + info->xmit_head, tmp_buf, c);
      info->xmit_head = ((info->xmit_head + c) & (DZ_XMIT_SIZE-1));
      info->xmit_cnt += c;

      restore_flags(flags);

      buf += c;
      count -= c;
      ret += c;
    }
    
    up (&tmp_buf_sem);
  } else {


    while (1) {
      save_flags (flags);
      cli ();     

      c = MIN(count, MIN(DZ_XMIT_SIZE - info->xmit_cnt - 1, DZ_XMIT_SIZE - info->xmit_head));
      if (c <= 0) {
        restore_flags (flags);
        break;
      }
      memcpy (info->xmit_buf + info->xmit_head, buf, c);
      info->xmit_head = ((info->xmit_head + c) & (DZ_XMIT_SIZE-1));
      info->xmit_cnt += c;

      restore_flags (flags);

      buf += c;
      count -= c;
      ret += c;
    }
  }


  if (info->xmit_cnt)
    {
      if (!tty->stopped) 
	{
	  if (!tty->hw_stopped)
	    {
	      dz_start (info->tty);
	    }
	}
    }
  return ret;
}

/* 
 * -------------------------------------------------------------------
 * dz_write_room ()
 *
 * compute the amount of space available for writing.
 * ------------------------------------------------------------------- 
 */
static int dz_write_room (struct tty_struct *tty)
{
  struct dz_serial *info = (struct dz_serial *)tty->driver_data;
  int ret;
                                
  ret = DZ_XMIT_SIZE - info->xmit_cnt - 1;
  if (ret < 0) ret = 0;
  return ret;
}

/* 
 * -------------------------------------------------------------------
 * dz_chars_in_buffer ()
 *
 * compute the amount of char left to be transmitted
 * ------------------------------------------------------------------- 
 */
static int dz_chars_in_buffer (struct tty_struct *tty)
{
  struct dz_serial *info = (struct dz_serial *)tty->driver_data;
  
  return info->xmit_cnt;
}

/* 
 * -------------------------------------------------------------------
 * dz_flush_buffer ()
 *
 * Empty the output buffer
 * ------------------------------------------------------------------- 
 */
static void dz_flush_buffer (struct tty_struct *tty)
{
  struct dz_serial *info = (struct dz_serial *)tty->driver_data;
                                
  cli ();
  info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
  sti ();

  wake_up_interruptible (&tty->write_wait);

  if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) && tty->ldisc.write_wakeup)
    (tty->ldisc.write_wakeup)(tty);
}

/*
 * ------------------------------------------------------------
 * dz_throttle () and dz_unthrottle ()
 * 
 * This routine is called by the upper-layer tty layer to signal that
 * incoming characters should be throttled (or not).
 * ------------------------------------------------------------
 */
static void dz_throttle (struct tty_struct *tty)
{
  struct dz_serial *info = (struct dz_serial *)tty->driver_data;  

  if (I_IXOFF(tty))
    info->x_char = STOP_CHAR(tty);
}

static void dz_unthrottle (struct tty_struct *tty)
{
  struct dz_serial *info = (struct dz_serial *)tty->driver_data;  

  if (I_IXOFF(tty)) {
    if (info->x_char)
      info->x_char = 0;
    else
      info->x_char = START_CHAR(tty);
  }
}

static void dz_send_xchar (struct tty_struct *tty, char ch)
{
  struct dz_serial *info = (struct dz_serial *)tty->driver_data;

  info->x_char = ch;

  if (ch) dz_start (info->tty);
}

/*
 * ------------------------------------------------------------
 * rs_ioctl () and friends
 * ------------------------------------------------------------
 */
static int get_serial_info (struct dz_serial *info, struct serial_struct *retinfo)
{
  struct serial_struct tmp;
  
  if (!retinfo)
    return -EFAULT;

  memset (&tmp, 0, sizeof(tmp));

  tmp.type = info->type;
  tmp.line = info->line;
  tmp.port = info->port;
  tmp.irq = SERIAL;
  tmp.flags = info->flags;
  tmp.baud_base = info->baud_base;
  tmp.close_delay = info->close_delay;
  tmp.closing_wait = info->closing_wait;
  
  return copy_to_user (retinfo, &tmp, sizeof(*retinfo));
}

static int set_serial_info (struct dz_serial *info, struct serial_struct *new_info)
{
  struct serial_struct new_serial;
  struct dz_serial old_info;
  int retval = 0;

  if (!new_info)
    return -EFAULT;

  if(copy_from_user (&new_serial, new_info, sizeof(new_serial)))
    return -EFAULT;
    
  old_info = *info;

  if (!capable(CAP_SYS_ADMIN))
    return -EPERM;

  if (info->count > 1)
    return -EBUSY;

  /*
   * OK, past this point, all the error checking has been done.
   * At this point, we start making changes.....
   */
  
  info->baud_base = new_serial.baud_base;
  info->type = new_serial.type;
  info->close_delay = new_serial.close_delay;
  info->closing_wait = new_serial.closing_wait;

  retval = startup (info);
  return retval;
}

/*
 * get_lsr_info - get line status register info
 *
 * Purpose: Let user call ioctl() to get info when the UART physically
 *          is emptied.  On bus types like RS485, the transmitter must
 *          release the bus after transmitting. This must be done when
 *          the transmit shift register is empty, not be done when the
 *          transmit holding register is empty.  This functionality
 *          allows an RS485 driver to be written in user space. 
 */
static int get_lsr_info (struct dz_serial *info, unsigned int *value)
{
  unsigned short status = dz_in (info, DZ_LPR);

  return put_user (status, value);
}

/*
 * This routine sends a break character out the serial port.
 */
static void send_break (struct dz_serial *info, int duration)
{
  unsigned long flags;
  unsigned short tmp, mask;

  if (!info->port)
    return;

  mask = 1 << info->line;
  tmp = dz_in (info, DZ_TCR);
  tmp |= mask;

  current->state = TASK_INTERRUPTIBLE;

  save_flags (flags);
  cli();
  
  dz_out (info, DZ_TCR, tmp);
  
  schedule_timeout(duration);
  
  tmp &= ~mask;
  dz_out (info, DZ_TCR, tmp);
  
  restore_flags (flags);
}

static int dz_ioctl (struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
{
  int error;
  struct dz_serial * info = (struct dz_serial *)tty->driver_data;
  int retval;

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

  switch (cmd) {
  case TCSBRK:    /* SVID version: non-zero arg --> no break */
    retval = tty_check_change (tty);
    if (retval)
      return retval;
    tty_wait_until_sent (tty, 0);
    if (!arg)
      send_break (info, HZ/4); /* 1/4 second */
    return 0;

  case TCSBRKP:   /* support for POSIX tcsendbreak() */
    retval = tty_check_change (tty);
    if (retval)
      return retval;
    tty_wait_until_sent (tty, 0);
    send_break (info, arg ? arg*(HZ/10) : HZ/4);
    return 0;

  case TIOCGSOFTCAR:
    error = verify_area (VERIFY_WRITE, (void *)arg, sizeof(long));
    if (error)
      return error;
    put_user (C_CLOCAL(tty) ? 1 : 0, (unsigned long *)arg);
    return 0;

  case TIOCSSOFTCAR:
    error = get_user (arg, (unsigned long *)arg);
    if (error)
      return error;
    tty->termios->c_cflag = ((tty->termios->c_cflag & ~CLOCAL) | (arg ? CLOCAL : 0));
    return 0;

  case TIOCGSERIAL:
    error = verify_area (VERIFY_WRITE, (void *)arg, sizeof(struct serial_struct));
    if (error)
      return error;
    return get_serial_info (info, (struct serial_struct *)arg);

  case TIOCSSERIAL:
    return set_serial_info (info, (struct serial_struct *) arg);

  case TIOCSERGETLSR: /* Get line status register */
    error = verify_area (VERIFY_WRITE, (void *)arg, sizeof(unsigned int));
    if (error)
      return error;
    else
      return get_lsr_info (info, (unsigned int *)arg);

  case TIOCSERGSTRUCT:
    error = verify_area (VERIFY_WRITE, (void *)arg, sizeof(struct dz_serial));
    if (error)
      return error;
    copy_to_user((struct dz_serial *)arg, info, sizeof(struct dz_serial));
    return 0;
    
  default:
    return -ENOIOCTLCMD;
  }

  return 0;
}

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

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

  change_speed (info);

  if ((old_termios->c_cflag & CRTSCTS) &&
      !(tty->termios->c_cflag & CRTSCTS)) {
    tty->hw_stopped = 0;
    dz_start (tty);
  }
}

/*
 * ------------------------------------------------------------
 * dz_close()
 * 
 * This routine is called when the serial port gets closed.  First, we
 * wait for the last remaining data to be sent.  Then, we turn off
 * the transmit enable and receive enable flags.
 * ------------------------------------------------------------
 */
static void dz_close (struct tty_struct *tty, struct file *filp)
{
  struct dz_serial * info = (struct dz_serial *)tty->driver_data;
  unsigned long flags;

  if (!info) return;
        
  save_flags (flags); 
  cli();
        
  if (tty_hung_up_p (filp)) {
    restore_flags (flags);
    return;
  }

  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("dz_close: bad serial port count; tty->count is 1, "
                       "info->count is %d\n", info->count);
                info->count = 1;
  }

  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 */

