binutils-gdb/gdb/ser-go32.c

/* Remote serial interface for local (hardwired) serial ports for GO32.
   Copyright (C) 1992, 1993, 2000, 2001, 2007, 2008, 2009, 2010, 2011
   Free Software Foundation, Inc.

   Contributed by Nigel Stephens, Algorithmics Ltd. (nigel@algor.co.uk).

   This version uses DPMI interrupts to handle buffered i/o
   without the separate "asynctsr" program.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "gdbcmd.h"
#include "serial.h"
#include "gdb_string.h"


/*
 * NS16550 UART registers
 */

#define COM1ADDR	0x3f8
#define COM2ADDR	0x2f8
#define COM3ADDR	0x3e8
#define COM4ADDR	0x3e0

#define	com_data	0	/* data register (R/W) */
#define	com_dlbl	0	/* divisor latch low (W) */
#define	com_ier		1	/* interrupt enable (W) */
#define	com_dlbh	1	/* divisor latch high (W) */
#define	com_iir		2	/* interrupt identification (R) */
#define	com_fifo	2	/* FIFO control (W) */
#define	com_lctl	3	/* line control register (R/W) */
#define	com_cfcr	3	/* line control register (R/W) */
#define	com_mcr		4	/* modem control register (R/W) */
#define	com_lsr		5	/* line status register (R/W) */
#define	com_msr		6	/* modem status register (R/W) */

/*
 * Constants for computing 16 bit baud rate divisor (lower byte
 * in com_dlbl, upper in com_dlbh) from 1.8432MHz crystal.  Divisor is
 * 1.8432 MHz / (16 * X) for X bps.  If the baud rate can't be set
 * to within +- (desired_rate*SPEED_TOLERANCE/1000) bps, we fail.
 */
#define COMTICK		(1843200/16)
#define SPEED_TOLERANCE	30	/* thousandths; real == desired +- 3.0% */

/* interrupt enable register */
#define	IER_ERXRDY	0x1	/* int on rx ready */
#define	IER_ETXRDY	0x2	/* int on tx ready */
#define	IER_ERLS	0x4	/* int on line status change */
#define	IER_EMSC	0x8	/* int on modem status change */

/* interrupt identification register */
#define	IIR_FIFO_MASK	0xc0	/* set if FIFOs are enabled */
#define	IIR_IMASK	0xf	/* interrupt cause mask */
#define	IIR_NOPEND	0x1	/* nothing pending */
#define	IIR_RLS		0x6	/* receive line status */
#define	IIR_RXRDY	0x4	/* receive ready */
#define	IIR_RXTOUT	0xc	/* receive timeout */
#define	IIR_TXRDY	0x2	/* transmit ready */
#define	IIR_MLSC	0x0	/* modem status */


/* fifo control register */
#define	FIFO_ENABLE	0x01	/* enable fifo */
#define	FIFO_RCV_RST	0x02	/* reset receive fifo */
#define	FIFO_XMT_RST	0x04	/* reset transmit fifo */
#define	FIFO_DMA_MODE	0x08	/* enable dma mode */
#define	FIFO_TRIGGER_1	0x00	/* trigger at 1 char */
#define	FIFO_TRIGGER_4	0x40	/* trigger at 4 chars */
#define	FIFO_TRIGGER_8	0x80	/* trigger at 8 chars */
#define	FIFO_TRIGGER_14	0xc0	/* trigger at 14 chars */

/* character format control register */
#define	CFCR_DLAB	0x80	/* divisor latch */
#define	CFCR_SBREAK	0x40	/* send break */
#define	CFCR_PZERO	0x30	/* zero parity */
#define	CFCR_PONE	0x20	/* one parity */
#define	CFCR_PEVEN	0x10	/* even parity */
#define	CFCR_PODD	0x00	/* odd parity */
#define	CFCR_PENAB	0x08	/* parity enable */
#define	CFCR_STOPB	0x04	/* 2 stop bits */
#define	CFCR_8BITS	0x03	/* 8 data bits */
#define	CFCR_7BITS	0x02	/* 7 data bits */
#define	CFCR_6BITS	0x01	/* 6 data bits */
#define	CFCR_5BITS	0x00	/* 5 data bits */

/* modem control register */
#define	MCR_LOOPBACK	0x10	/* loopback */
#define	MCR_IENABLE	0x08	/* output 2 = int enable */
#define	MCR_DRS		0x04	/* output 1 = xxx */
#define	MCR_RTS		0x02	/* enable RTS */
#define	MCR_DTR		0x01	/* enable DTR */

/* line status register */
#define	LSR_RCV_FIFO	0x80	/* error in receive fifo */
#define	LSR_TSRE	0x40	/* transmitter empty */
#define	LSR_TXRDY	0x20	/* transmitter ready */
#define	LSR_BI		0x10	/* break detected */
#define	LSR_FE		0x08	/* framing error */
#define	LSR_PE		0x04	/* parity error */
#define	LSR_OE		0x02	/* overrun error */
#define	LSR_RXRDY	0x01	/* receiver ready */
#define	LSR_RCV_MASK	0x1f

/* modem status register */
#define	MSR_DCD		0x80
#define	MSR_RI		0x40
#define	MSR_DSR		0x20
#define	MSR_CTS		0x10
#define	MSR_DDCD	0x08
#define	MSR_TERI	0x04
#define	MSR_DDSR	0x02
#define	MSR_DCTS	0x01

#include <time.h>
#include <dos.h>
#include <go32.h>
#include <dpmi.h>
typedef unsigned long u_long;

/* 16550 rx fifo trigger point */
#define FIFO_TRIGGER	FIFO_TRIGGER_4

/* input buffer size */
#define CBSIZE	4096

#define RAWHZ	18

#ifdef DOS_STATS
#define CNT_RX		16
#define CNT_TX		17
#define CNT_STRAY	18
#define CNT_ORUN	19
#define NCNT		20

static int intrcnt;
static int cnts[NCNT];
static char *cntnames[NCNT] =
{
  /* h/w interrupt counts.  */
  "mlsc", "nopend", "txrdy", "?3",
  "rxrdy", "?5", "rls", "?7",
  "?8", "?9", "?a", "?b",
  "rxtout", "?d", "?e", "?f",
  /* s/w counts.  */
  "rxcnt", "txcnt", "stray", "swoflo"
};

#define COUNT(x) cnts[x]++
#else
#define COUNT(x)
#endif

/* Main interrupt controller port addresses.  */
#define ICU_BASE	0x20
#define ICU_OCW2	(ICU_BASE + 0)
#define ICU_MASK	(ICU_BASE + 1)

/* Original interrupt controller mask register.  */
unsigned char icu_oldmask;

/* Maximum of 8 interrupts (we don't handle the slave icu yet).  */
#define NINTR	8

static struct intrupt
  {
    char inuse;
    struct dos_ttystate *port;
    _go32_dpmi_seginfo old_rmhandler;
    _go32_dpmi_seginfo old_pmhandler;
    _go32_dpmi_seginfo new_rmhandler;
    _go32_dpmi_seginfo new_pmhandler;
    _go32_dpmi_registers regs;
  }
intrupts[NINTR];


static struct dos_ttystate
  {
    int base;
    int irq;
    int refcnt;
    struct intrupt *intrupt;
    int fifo;
    int baudrate;
    unsigned char cbuf[CBSIZE];
    unsigned int first;
    unsigned int count;
    int txbusy;
    unsigned char old_mcr;
    int ferr;
    int perr;
    int oflo;
    int msr;
  }
ports[4] =
{
  {
    COM1ADDR, 4, 0, NULL, 0, 0, "", 0, 0, 0, 0, 0, 0, 0, 0
  }
  ,
  {
    COM2ADDR, 3, 0, NULL, 0, 0, "", 0, 0, 0, 0, 0, 0, 0, 0
  }
  ,
  {
    COM3ADDR, 4, 0, NULL, 0, 0, "", 0, 0, 0, 0, 0, 0, 0, 0
  }
  ,
  {
    COM4ADDR, 3, 0, NULL, 0, 0, "", 0, 0, 0, 0, 0, 0, 0, 0
  }
};

static int dos_open (struct serial *scb, const char *name);
static void dos_raw (struct serial *scb);
static int dos_readchar (struct serial *scb, int timeout);
static int dos_setbaudrate (struct serial *scb, int rate);
static int dos_write (struct serial *scb, const char *str, int len);
static void dos_close (struct serial *scb);
static serial_ttystate dos_get_tty_state (struct serial *scb);
static int dos_set_tty_state (struct serial *scb, serial_ttystate state);
static int dos_baudconv (int rate);

#define inb(p,a)	inportb((p)->base + (a))
#define outb(p,a,v)	outportb((p)->base + (a), (v))
#define disable()	asm volatile ("cli");
#define enable()	asm volatile ("sti");


static int
dos_getc (volatile struct dos_ttystate *port)
{
  int c;

  if (port->count == 0)
    return -1;

  c = port->cbuf[port->first];
  disable ();
  port->first = (port->first + 1) & (CBSIZE - 1);
  port->count--;
  enable ();
  return c;
}


static int
dos_putc (int c, struct dos_ttystate *port)
{
  if (port->count >= CBSIZE - 1)
    return -1;
  port->cbuf[(port->first + port->count) & (CBSIZE - 1)] = c;
  port->count++;
  return 0;
}



static void
dos_comisr (int irq)
{
  struct dos_ttystate *port;
  unsigned char iir, lsr, c;

  disable ();			/* Paranoia */
  outportb (ICU_OCW2, 0x20);	/* End-Of-Interrupt */
#ifdef DOS_STATS
  ++intrcnt;
#endif

  port = intrupts[irq].port;
  if (!port)
    {
      COUNT (CNT_STRAY);
      return;			/* not open */
    }

  while (1)
    {
      iir = inb (port, com_iir) & IIR_IMASK;
      switch (iir)
	{

	case IIR_RLS:
	  lsr = inb (port, com_lsr);
	  goto rx;

	case IIR_RXTOUT:
	case IIR_RXRDY:
	  lsr = 0;

	rx:
	  do
	    {
	      c = inb (port, com_data);
	      if (lsr & (LSR_BI | LSR_FE | LSR_PE | LSR_OE))
		{
		  if (lsr & (LSR_BI | LSR_FE))
		    port->ferr++;
		  else if (lsr & LSR_PE)
		    port->perr++;
		  if (lsr & LSR_OE)
		    port->oflo++;
		}

	      if (dos_putc (c, port) < 0)
		{
		  COUNT (CNT_ORUN);
		}
	      else
		{
		  COUNT (CNT_RX);
		}
	    }
	  while ((lsr = inb (port, com_lsr)) & LSR_RXRDY);
	  break;

	case IIR_MLSC:
	  /* could be used to flowcontrol Tx */
	  port->msr = inb (port, com_msr);
	  break;

	case IIR_TXRDY:
	  port->txbusy = 0;
	  break;

	case IIR_NOPEND:
	  /* No more pending interrupts, all done.  */
	  return;

	default:
	  /* Unexpected interrupt, ignore.  */
	  break;
	}
      COUNT (iir);
    }
}

#define ISRNAME(x) dos_comisr##x
#define ISR(x) static void ISRNAME(x)(void) {dos_comisr(x);}

ISR (0) ISR (1) ISR (2) ISR (3) /* OK */
ISR (4) ISR (5) ISR (6) ISR (7) /* OK */

typedef void (*isr_t) (void);

static isr_t isrs[NINTR] =
  {
       ISRNAME (0), ISRNAME (1), ISRNAME (2), ISRNAME (3),
       ISRNAME (4), ISRNAME (5), ISRNAME (6), ISRNAME (7)
  };



static struct intrupt *
dos_hookirq (unsigned int irq)
{
  struct intrupt *intr;
  unsigned int vec;
  isr_t isr;

  if (irq >= NINTR)
    return 0;

  intr = &intrupts[irq];
  if (intr->inuse)
    return 0;

  vec = 0x08 + irq;
  isr = isrs[irq];

  /* Setup real mode handler.  */
  _go32_dpmi_get_real_mode_interrupt_vector (vec, &intr->old_rmhandler);

  intr->new_rmhandler.pm_selector = _go32_my_cs ();
  intr->new_rmhandler.pm_offset = (u_long) isr;
  if (_go32_dpmi_allocate_real_mode_callback_iret (&intr->new_rmhandler,
						   &intr->regs))
    {
      return 0;
    }

  if (_go32_dpmi_set_real_mode_interrupt_vector (vec, &intr->new_rmhandler))
    {
      return 0;
    }

  /* Setup protected mode handler.  */
  _go32_dpmi_get_protected_mode_interrupt_vector (vec, &intr->old_pmhandler);

  intr->new_pmhandler.pm_selector = _go32_my_cs ();
  intr->new_pmhandler.pm_offset = (u_long) isr;
  _go32_dpmi_allocate_iret_wrapper (&intr->new_pmhandler);

  if (_go32_dpmi_set_protected_mode_interrupt_vector (vec,
						      &intr->new_pmhandler))
    {
      return 0;
    }

  /* Setup interrupt controller mask.  */
  disable ();
  outportb (ICU_MASK, inportb (ICU_MASK) & ~(1 << irq));
  enable ();

  intr->inuse = 1;
  return intr;
}


static void
dos_unhookirq (struct intrupt *intr)
{
  unsigned int irq, vec;
  unsigned char mask;

  irq = intr - intrupts;
  vec = 0x08 + irq;

  /* Restore old interrupt mask bit.  */
  mask = 1 << irq;
  disable ();
  outportb (ICU_MASK, inportb (ICU_MASK) | (mask & icu_oldmask));
  enable ();

  /* Remove real mode handler.  */
  _go32_dpmi_set_real_mode_interrupt_vector (vec, &intr->old_rmhandler);
  _go32_dpmi_free_real_mode_callback (&intr->new_rmhandler);

  /* Remove protected mode handler.  */
  _go32_dpmi_set_protected_mode_interrupt_vector (vec, &intr->old_pmhandler);
  _go32_dpmi_free_iret_wrapper (&intr->new_pmhandler);
  intr->inuse = 0;
}



static int
dos_open (struct serial *scb, const char *name)
{
  struct dos_ttystate *port;
  int fd, i;

  if (strncasecmp (name, "/dev/", 5) == 0)
    name += 5;
  else if (strncasecmp (name, "\\dev\\", 5) == 0)
    name += 5;

  if (strlen (name) != 4 || strncasecmp (name, "com", 3) != 0)
    {
      errno = ENOENT;
      return -1;
    }

  if (name[3] < '1' || name[3] > '4')
    {
      errno = ENOENT;
      return -1;
    }

  /* FIXME: this is a Bad Idea (tm)!  One should *never* invent file
     handles, since they might be already used by other files/devices.
     The Right Way to do this is to create a real handle by dup()'ing
     some existing one.  */
  fd = name[3] - '1';
  port = &ports[fd];
  if (port->refcnt++ > 0)
    {
      /* Device already opened another user.  Just point at it.  */
      scb->fd = fd;
      return 0;
    }

  /* Force access to ID reg.  */
  outb (port, com_cfcr, 0);
  outb (port, com_iir, 0);
  for (i = 0; i < 17; i++)
    {
      if ((inb (port, com_iir) & 0x38) == 0)
	goto ok;
      (void) inb (port, com_data);	/* clear recv */
    }
  errno = ENODEV;
  return -1;

ok:
  /* Disable all interrupts in chip.  */
  outb (port, com_ier, 0);

  /* Tentatively enable 16550 fifo, and see if it responds.  */
  outb (port, com_fifo,
	FIFO_ENABLE | FIFO_RCV_RST | FIFO_XMT_RST | FIFO_TRIGGER);
  sleep (1);
  port->fifo = ((inb (port, com_iir) & IIR_FIFO_MASK) == IIR_FIFO_MASK);

  /* clear pending status reports.  */
  (void) inb (port, com_lsr);
  (void) inb (port, com_msr);

  /* Enable external interrupt gate (to avoid floating IRQ).  */
  outb (port, com_mcr, MCR_IENABLE);

  /* Hook up interrupt handler and initialise icu.  */
  port->intrupt = dos_hookirq (port->irq);
  if (!port->intrupt)
    {
      outb (port, com_mcr, 0);
      outb (port, com_fifo, 0);
      errno = ENODEV;
      return -1;
    }

  disable ();

  /* record port */
  port->intrupt->port = port;
  scb->fd = fd;

  /* Clear rx buffer, tx busy flag and overflow count.  */
  port->first = port->count = 0;
  port->txbusy = 0;
  port->oflo = 0;

  /* Set default baud rate and mode: 9600,8,n,1 */
  i = dos_baudconv (port->baudrate = 9600);
  outb (port, com_cfcr, CFCR_DLAB);
  outb (port, com_dlbl, i & 0xff);
  outb (port, com_dlbh, i >> 8);
  outb (port, com_cfcr, CFCR_8BITS);

  /* Enable all interrupts.  */
  outb (port, com_ier, IER_ETXRDY | IER_ERXRDY | IER_ERLS | IER_EMSC);

  /* Enable DTR & RTS.  */
  outb (port, com_mcr, MCR_DTR | MCR_RTS | MCR_IENABLE);

  enable ();

  return 0;
}


static void
dos_close (struct serial *scb)
{
  struct dos_ttystate *port;
  struct intrupt *intrupt;

  if (!scb)
    return;

  port = &ports[scb->fd];

  if (port->refcnt-- > 1)
    return;

  if (!(intrupt = port->intrupt))
    return;

  /* Disable interrupts, fifo, flow control.  */
  disable ();
  port->intrupt = 0;
  intrupt->port = 0;
  outb (port, com_fifo, 0);
  outb (port, com_ier, 0);
  enable ();

  /* Unhook handler, and disable interrupt gate.  */
  dos_unhookirq (intrupt);
  outb (port, com_mcr, 0);

  /* Check for overflow errors.  */
  if (port->oflo)
    {
      fprintf_unfiltered (gdb_stderr,
			  "Serial input overruns occurred.\n");
      fprintf_unfiltered (gdb_stderr, "This system %s handle %d baud.\n",
			  port->fifo ? "cannot" : "needs a 16550 to",
			  port->baudrate);
    }
}



static int
dos_noop (struct serial *scb)
{
  return 0;
}

static void
dos_raw (struct serial *scb)
{
  /* Always in raw mode.  */
}

static int
dos_readchar (struct serial *scb, int timeout)
{
  struct dos_ttystate *port = &ports[scb->fd];
  long then;
  int c;

  then = rawclock () + (timeout * RAWHZ);
  while ((c = dos_getc (port)) < 0)
    {
      if (timeout >= 0 && (rawclock () - then) >= 0)
	return SERIAL_TIMEOUT;
    }

  return c;
}


static serial_ttystate
dos_get_tty_state (struct serial *scb)
{
  struct dos_ttystate *port = &ports[scb->fd];
  struct dos_ttystate *state;

  /* Are they asking about a port we opened?  */
  if (port->refcnt <= 0)
    {
      /* We've never heard about this port.  We should fail this call,
	 unless they are asking about one of the 3 standard handles,
	 in which case we pretend the handle was open by us if it is
	 connected to a terminal device.  This is beacuse Unix
	 terminals use the serial interface, so GDB expects the
	 standard handles to go through here.  */
      if (scb->fd >= 3 || !isatty (scb->fd))
	return NULL;
    }

  state = (struct dos_ttystate *) xmalloc (sizeof *state);
  *state = *port;
  return (serial_ttystate) state;
}

static serial_ttystate
dos_copy_tty_state (struct serial *scb, serial_ttystate ttystate)
{
  struct dos_ttystate *state;

  state = (struct dos_ttystate *) xmalloc (sizeof *state);
  *state = *(struct dos_ttystate *) ttystate;

  return (serial_ttystate) state;
}

static int
dos_set_tty_state (struct serial *scb, serial_ttystate ttystate)
{
  struct dos_ttystate *state;

  state = (struct dos_ttystate *) ttystate;
  dos_setbaudrate (scb, state->baudrate);
  return 0;
}

static int
dos_noflush_set_tty_state (struct serial *scb, serial_ttystate new_ttystate,
			   serial_ttystate old_ttystate)
{
  struct dos_ttystate *state;

  state = (struct dos_ttystate *) new_ttystate;
  dos_setbaudrate (scb, state->baudrate);
  return 0;
}

static int
dos_flush_input (struct serial *scb)
{
  struct dos_ttystate *port = &ports[scb->fd];

  disable ();
  port->first = port->count = 0;
  if (port->fifo)
    outb (port, com_fifo, FIFO_ENABLE | FIFO_RCV_RST | FIFO_TRIGGER);
  enable ();
  return 0;
}

static void
dos_print_tty_state (struct serial *scb, serial_ttystate ttystate,
		     struct ui_file *stream)
{
  /* Nothing to print.  */
  return;
}

static int
dos_baudconv (int rate)
{
  long x, err;

  if (rate <= 0)
    return -1;

#define divrnd(n, q)	(((n) * 2 / (q) + 1) / 2) /* Divide and round off.  */
  x = divrnd (COMTICK, rate);
  if (x <= 0)
    return -1;

  err = divrnd (1000 * COMTICK, x * rate) - 1000;
  if (err < 0)
    err = -err;
  if (err > SPEED_TOLERANCE)
    return -1;
#undef divrnd
  return x;
}


static int
dos_setbaudrate (struct serial *scb, int rate)
{
  struct dos_ttystate *port = &ports[scb->fd];

  if (port->baudrate != rate)
    {
      int x;
      unsigned char cfcr;

      x = dos_baudconv (rate);
      if (x <= 0)
	{
	  fprintf_unfiltered (gdb_stderr, "%d: impossible baudrate\n", rate);
	  errno = EINVAL;
	  return -1;
	}

      disable ();
      cfcr = inb (port, com_cfcr);

      outb (port, com_cfcr, CFCR_DLAB);
      outb (port, com_dlbl, x & 0xff);
      outb (port, com_dlbh, x >> 8);
      outb (port, com_cfcr, cfcr);
      port->baudrate = rate;
      enable ();
    }

  return 0;
}

static int
dos_setstopbits (struct serial *scb, int num)
{
  struct dos_ttystate *port = &ports[scb->fd];
  unsigned char cfcr;

  disable ();
  cfcr = inb (port, com_cfcr);

  switch (num)
    {
    case SERIAL_1_STOPBITS:
      outb (port, com_cfcr, cfcr & ~CFCR_STOPB);
      break;
    case SERIAL_1_AND_A_HALF_STOPBITS:
    case SERIAL_2_STOPBITS:
      outb (port, com_cfcr, cfcr | CFCR_STOPB);
      break;
    default:
      enable ();
      return 1;
    }
  enable ();

  return 0;
}

static int
dos_write (struct serial *scb, const char *str, int len)
{
  volatile struct dos_ttystate *port = &ports[scb->fd];
  int fifosize = port->fifo ? 16 : 1;
  long then;
  int cnt;

  while (len > 0)
    {
      /* Send the data, fifosize bytes at a time.  */
      cnt = fifosize > len ? len : fifosize;
      port->txbusy = 1;
      /* Francisco Pastor <fpastor.etra-id@etra.es> says OUTSB messes
	 up the communications with UARTs with FIFOs.  */
#ifdef UART_FIFO_WORKS
      outportsb (port->base + com_data, str, cnt);
      str += cnt;
      len -= cnt;
#else
      for ( ; cnt > 0; cnt--, len--)
	outportb (port->base + com_data, *str++);
#endif
#ifdef DOS_STATS
      cnts[CNT_TX] += cnt;
#endif
      /* Wait for transmission to complete (max 1 sec).  */
      then = rawclock () + RAWHZ;
      while (port->txbusy)
	{
	  if ((rawclock () - then) >= 0)
	    {
	      errno = EIO;
	      return SERIAL_ERROR;
	    }
	}
    }
  return 0;
}


static int
dos_sendbreak (struct serial *scb)
{
  volatile struct dos_ttystate *port = &ports[scb->fd];
  unsigned char cfcr;
  long then;

  cfcr = inb (port, com_cfcr);
  outb (port, com_cfcr, cfcr | CFCR_SBREAK);

  /* 0.25 sec delay */
  then = rawclock () + RAWHZ / 4;
  while ((rawclock () - then) < 0)
    continue;

  outb (port, com_cfcr, cfcr);
  return 0;
}


static struct serial_ops dos_ops =
{
  "hardwire",
  0,
  dos_open,
  dos_close,
  NULL,				/* fdopen, not implemented */
  dos_readchar,
  dos_write,
  dos_noop,			/* flush output */
  dos_flush_input,
  dos_sendbreak,
  dos_raw,
  dos_get_tty_state,
  dos_copy_tty_state,
  dos_set_tty_state,
  dos_print_tty_state,
  dos_noflush_set_tty_state,
  dos_setbaudrate,
  dos_setstopbits,
  dos_noop,			/* Wait for output to drain.  */
  (void (*)(struct serial *, int))NULL	/* Change into async mode.  */
};

int
gdb_pipe (int pdes[2])
{
  /* No support for pipes.  */
  errno = ENOSYS;
  return -1;
}

static void
dos_info (char *arg, int from_tty)
{
  struct dos_ttystate *port;
#ifdef DOS_STATS
  int i;
#endif

  for (port = ports; port < &ports[4]; port++)
    {
      if (port->baudrate == 0)
	continue;
      printf_filtered ("Port:\tCOM%ld (%sactive)\n", (long)(port - ports) + 1,
		       port->intrupt ? "" : "not ");
      printf_filtered ("Addr:\t0x%03x (irq %d)\n", port->base, port->irq);
      printf_filtered ("16550:\t%s\n", port->fifo ? "yes" : "no");
      printf_filtered ("Speed:\t%d baud\n", port->baudrate);
      printf_filtered ("Errs:\tframing %d parity %d overflow %d\n\n",
		       port->ferr, port->perr, port->oflo);
    }

#ifdef DOS_STATS
  printf_filtered ("\nTotal interrupts: %d\n", intrcnt);
  for (i = 0; i < NCNT; i++)
    if (cnts[i])
      printf_filtered ("%s:\t%d\n", cntnames[i], cnts[i]);
#endif
}


void
_initialize_ser_dos (void)
{
  serial_add_interface (&dos_ops);

  /* Save original interrupt mask register.  */
  icu_oldmask = inportb (ICU_MASK);

  /* Mark fixed motherboard irqs as inuse.  */
  intrupts[0].inuse =		/* timer tick */
    intrupts[1].inuse =		/* keyboard */
    intrupts[2].inuse = 1;	/* slave icu */

  add_setshow_zinteger_cmd ("com1base", class_obscure, &ports[0].base, _("\
Set COM1 base i/o port address."), _("\
Show COM1 base i/o port address."), NULL,
			    NULL,
			    NULL, /* FIXME: i18n: */
			    &setlist, &showlist);

  add_setshow_zinteger_cmd ("com1irq", class_obscure, &ports[0].irq, _("\
Set COM1 interrupt request."), _("\
Show COM1 interrupt request."), NULL,
			    NULL,
			    NULL, /* FIXME: i18n: */
			    &setlist, &showlist);

  add_setshow_zinteger_cmd ("com2base", class_obscure, &ports[1].base, _("\
Set COM2 base i/o port address."), _("\
Show COM2 base i/o port address."), NULL,
			    NULL,
			    NULL, /* FIXME: i18n: */
			    &setlist, &showlist);

  add_setshow_zinteger_cmd ("com2irq", class_obscure, &ports[1].irq, _("\
Set COM2 interrupt request."), _("\
Show COM2 interrupt request."), NULL,
			    NULL,
			    NULL, /* FIXME: i18n: */
			    &setlist, &showlist);

  add_setshow_zinteger_cmd ("com3base", class_obscure, &ports[2].base, _("\
Set COM3 base i/o port address."), _("\
Show COM3 base i/o port address."), NULL,
			    NULL,
			    NULL, /* FIXME: i18n: */
			    &setlist, &showlist);

  add_setshow_zinteger_cmd ("com3irq", class_obscure, &ports[2].irq, _("\
Set COM3 interrupt request."), _("\
Show COM3 interrupt request."), NULL,
			    NULL,
			    NULL, /* FIXME: i18n: */
			    &setlist, &showlist);

  add_setshow_zinteger_cmd ("com4base", class_obscure, &ports[3].base, _("\
Set COM4 base i/o port address."), _("\
Show COM4 base i/o port address."), NULL,
			    NULL,
			    NULL, /* FIXME: i18n: */
			    &setlist, &showlist);

  add_setshow_zinteger_cmd ("com4irq", class_obscure, &ports[3].irq, _("\
Set COM4 interrupt request."), _("\
Show COM4 interrupt request."), NULL,
			    NULL,
			    NULL, /* FIXME: i18n: */
			    &setlist, &showlist);

  add_info ("serial", dos_info,
	    _("Print DOS serial port status."));
}