/*
 * 86Box	A hypervisor and IBM PC system emulator that specializes in
 *		running old operating systems and software designed for IBM
 *		PC systems and compatibles from 1981 through fairly recent
 *		system designs based on the PCI bus.
 *
 *		This file is part of the 86Box distribution.
 *
 *		Implementation of Port 92 used by PS/2 machines and 386+
 *		clones.
 *
 *
 *
 * Authors:	Miran Grca, <mgrca8@gmail.com>
 *
 *		Copyright 2019 Miran Grca.
 */
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <86box/86box.h>
#include <86box/device.h>
#include "cpu.h"
#include <86box/timer.h>
#include <86box/io.h>
#include <86box/keyboard.h>
#include <86box/mem.h>
#include <86box/pit.h>
#include <86box/port_92.h>


#define	 PORT_92_INV	1
#define	 PORT_92_WORD	2
#define	 PORT_92_PCI	4
#define  PORT_92_RESET	8
#define  PORT_92_A20	16


static uint8_t
port_92_readb(uint16_t port, void *priv)
{
    uint8_t ret = 0x00;
    port_92_t *dev = (port_92_t *) priv;

    if (port == 0x92) {
	/* Return bit 1 directly from mem_a20_alt, so the
	   pin can be reset independently of the device. */
	ret = (dev->reg & ~0x03) | (mem_a20_alt & 2) |
	      (cpu_alt_reset & 1);

	if (dev->flags & PORT_92_INV)
		ret |= 0xfc;
	else if (dev->flags & PORT_92_PCI)
		ret |= 0x24;	/* Intel SIO datasheet says bits 2 and 5 are always 1. */
    } else if (dev->flags & PORT_92_INV)
	ret = 0xff;

    return ret;
}


static uint16_t
port_92_readw(uint16_t port, void *priv)
{
    return port_92_readb(port, priv);
}


static void
port_92_pulse(void *priv)
{
    softresetx86();
    cpu_set_edx();
}


static void
port_92_writeb(uint16_t port, uint8_t val, void *priv)
{
    port_92_t *dev = (port_92_t *) priv;

    if (port != 0x92)
	return;

    dev->reg = val & 0x03;

    if ((mem_a20_alt ^ val) & 2) {
	mem_a20_alt = (val & 2);
	mem_a20_recalc();
    }

    if ((~cpu_alt_reset & val) & 1)
	timer_set_delay_u64(&dev->pulse_timer, dev->pulse_period);
    else if (!(val & 1))
	timer_disable(&dev->pulse_timer);

    cpu_alt_reset = (val & 1);

    if (dev->flags & PORT_92_INV)
	dev->reg |= 0xfc;
}


static void
port_92_writew(uint16_t port, uint16_t val, void *priv)
{
    port_92_writeb(port, val & 0xff, priv);
}


void
port_92_set_period(void *priv, uint64_t pulse_period)
{
    port_92_t *dev = (port_92_t *) priv;

    dev->pulse_period = pulse_period;
}


void
port_92_set_features(void *priv, int reset, int a20)
{
    port_92_t *dev = (port_92_t *) priv;

    dev->flags &= ~(PORT_92_RESET | PORT_92_A20);

    if (reset)
	dev->flags |= PORT_92_RESET;

    timer_disable(&dev->pulse_timer);

    if (a20) {
	dev->flags |= PORT_92_A20;
	mem_a20_alt = (dev->reg & 2);
    } else
	mem_a20_alt = 0;

    mem_a20_recalc();
}


void
port_92_add(void *priv)
{
    port_92_t *dev = (port_92_t *) priv;

    if (dev->flags & PORT_92_WORD)
	    io_sethandler(0x0092, 2,
			  port_92_readb, port_92_readw, NULL, port_92_writeb, port_92_writew, NULL, dev);
    else
	    io_sethandler(0x0092, 1,
			  port_92_readb, NULL, NULL, port_92_writeb, NULL, NULL, dev);
}


void
port_92_remove(void *priv)
{
    port_92_t *dev = (port_92_t *) priv;

    if (dev->flags & PORT_92_WORD)
	    io_removehandler(0x0092, 2,
			     port_92_readb, port_92_readw, NULL, port_92_writeb, port_92_writew, NULL, dev);
    else
	    io_removehandler(0x0092, 1,
			     port_92_readb, NULL, NULL, port_92_writeb, NULL, NULL, dev);
}


static void
port_92_close(void *priv)
{
    port_92_t *dev = (port_92_t *) priv;

    timer_disable(&dev->pulse_timer);

    free(dev);
}


void *
port_92_init(const device_t *info)
{
    port_92_t *dev = (port_92_t *) malloc(sizeof(port_92_t));
    memset(dev, 0, sizeof(port_92_t));

    dev->flags = info->local & 0xff;

    timer_add(&dev->pulse_timer, port_92_pulse, dev, 0);

    dev->reg = 0;
    mem_a20_alt = 0;
    mem_a20_recalc();

    cpu_alt_reset = 0;

    flushmmucache();

    port_92_add(dev);

    dev->pulse_period = (uint64_t) (4.0 * SYSCLK * (double)(1ULL << 32ULL));

    dev->flags |= (PORT_92_RESET | PORT_92_A20);

    return dev;
}


const device_t port_92_device = {
    "Port 92 Register",
    0,
    0,
    port_92_init, port_92_close, NULL,
    NULL, NULL, NULL,
    NULL
};


const device_t port_92_inv_device = {
    "Port 92 Register (inverted bits 2-7)",
    0,
    PORT_92_INV,
    port_92_init, port_92_close, NULL,
    NULL, NULL, NULL,
    NULL
};


const device_t port_92_word_device = {
    "Port 92 Register (16-bit)",
    0,
    PORT_92_WORD,
    port_92_init, port_92_close, NULL,
    NULL, NULL, NULL,
    NULL
};


const device_t port_92_pci_device = {
    "Port 92 Register (PCI)",
    0,
    PORT_92_PCI,
    port_92_init, port_92_close, NULL,
    NULL, NULL, NULL,
    NULL
};