/*-
 * Copyright (c) 1996 Shin Takemura All rights reserved.
 *
 * This code is derived from i386/isa/kdbio.c.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote 
 *    products derived from this software without specific prior written 
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $Id: kbdio.c,v 1.1.4.1 1998/12/05 22:49:12 itojun Exp $
 */
#ifdef NECMG
#include "sc.h"
#include "vt.h"
#include "psm.h"
#include "opt_kbdio.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/syslog.h>
#include <machine/clock.h>
#include <i386/isa/isa.h>
#include <i386/isa/isa_device.h>
#include <i386/isa/kbdio.h>

/* I/O recovery time */
#define KBDC_DELAYTIME	20
#define KBDD_DELAYTIME	7

#ifndef max
#define max(x,y)	((x) > (y) ? (x) : (y))
#endif
#define kbdcp(p)	((struct kbdc_softc *)(p))

#define NKBDC		max(NSC, NVT)

struct kbdc_softc {
    int port;			/* base port address */
    int lock;			/* FIXME: XXX not quite a semaphore... */
}; 

static struct kbdc_softc kbdc_softc[NKBDC] = { { 0 }, };

/*
 *  associate a port number with a KBDC
 */
KBDC 
kbdc_open(int port)
{
    int s;
    int i;

    s = spltty();
    for (i = 0; i < NKBDC; ++i) {
        if (kbdc_softc[i].port == port) {
	    splx(s);
	    return (KBDC) &kbdc_softc[i];
	}
        if (kbdc_softc[i].port <= 0) {
	    kbdc_softc[i].port = port;
	    kbdc_softc[i].lock = FALSE;
	    splx(s);
	    return (KBDC) &kbdc_softc[i];
	}
    }
    splx(s);
    return NULL;
}

/*
 * I/O access arbitration in `kbdio'
 *
 * The `kbdio' module uses a simplistic convention to arbitrate
 * I/O access to the controller/keyboard/mouse. The convention requires
 * close cooperation of the calling device driver.
 *
 * The device driver which utilizes the `kbdio' module are assumed to
 * have the following set of routines.
 *    a. An interrupt handler (the bottom half of the driver).
 *    b. Timeout routines which may briefly polls the keyboard controller.
 *    c. Routines outside interrupt context (the top half of the driver).
 * They should follow the rules below:
 *    1. The interrupt handler may assume that it always has full access 
 *       to the controller/keyboard/mouse.
 *    2. The other routines must issue `spltty()' if they wish to 
 *       prevent the interrupt handler from accessing 
 *       the controller/keyboard/mouse.
 *    3. The timeout routines and the top half routines of the device driver
 *       arbitrate I/O access by observing the lock flag in `kbdio'.
 *       The flag is manipulated via `kbdc_lock()'; when one wants to
 *       perform I/O, call `kbdc_lock(kbdc, TRUE)' and proceed only if
 *       the call returns with TRUE. Otherwise the caller must back off.
 *       Call `kbdc_lock(kbdc, FALSE)' when necessary I/O operaion
 *       is finished. This mechanism does not prevent the interrupt 
 *       handler from being invoked at any time and carrying out I/O.
 *       Therefore, `spltty()' must be strategically placed in the device
 *       driver code. Also note that the timeout routine may interrupt
 *       `kbdc_lock()' called by the top half of the driver, but this
 *       interruption is OK so long as the timeout routine observes the
 *       the rule 4 below.
 *    4. The interrupt and timeout routines should not extend I/O operation
 *       across more than one interrupt or timeout; they must complete
 *       necessary I/O operation within one invokation of the routine.
 *       This measns that if the timeout routine acquires the lock flag,
 *       it must reset the flag to FALSE before it returns.
 */

/* set/reset polling lock */
int 
kbdc_lock(KBDC p, int lock)
{
    int prevlock;

    prevlock = kbdcp(p)->lock;
    kbdcp(p)->lock = lock;

    return (prevlock != lock);
}

/* check if any data is waiting to be processed */
int
kbdc_data_ready(KBDC p)
{
    return (inb(kbdcp(p)->port + KBD_STATUS_PORT) & 0x40);
}

static void
read_kbd_data_done(struct kbdc_softc *kbdc)
{
  unsigned char d;
  d = inb(kbdc->port + KBD_STATUS_PORT);
  outb(kbdc->port + KBD_STATUS_PORT, (d | 0x80));
  DELAY(KBDC_DELAYTIME);
  outb(kbdc->port + KBD_STATUS_PORT, d);
  DELAY(KBDC_DELAYTIME);
}

/* read one byte from the keyboard */
int
read_kbd_data(KBDC p)
{
  /* CPU will stay inside the loop for 200msec at most */
  struct kbdc_softc *kbdc = kbdcp(p);
  int retry = 10000;
  int port = kbdc->port;
  int d;

  while ((d = inb(port + KBD_DATA_PORT)) == 0) {
    DELAY(KBDD_DELAYTIME);
    if (--retry < 0)
      return -1; /* timeout */
  }
  read_kbd_data_done(kbdc);
  return (d);
}

/* read one byte from the keyboard, but return immediately if 
 * no data is waiting
 */
int
read_kbd_data_no_wait(KBDC p)
{
  int c;

  c = inb(kbdcp(p)->port + KBD_DATA_PORT);
  if (c == 0) {
    return (-1); /* no data */
  } else {
    read_kbd_data_done(kbdcp(p));
    return (c);
  }
}
#endif /* NECMG */