86Box/src/chipset/cs8230.c

/*
 * 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.
 *
 *		Emulation of C&T CS8230 ("386/AT") chipset.
 *
 *
 *
 * Authors:	Sarah Walker, <http://pcem-emulator.co.uk/>
 *
 *		Copyright 2020 Sarah Walker.
 */
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <86box/86box.h>
#include "cpu.h"
#include <86box/timer.h>
#include <86box/io.h>
#include <86box/device.h>
#include <86box/mem.h>
#include <86box/fdd.h>
#include <86box/fdc.h>
#include <86box/chipset.h>


typedef struct
{
    int		idx;
    uint8_t	regs[256];
} cs8230_t;


static void
shadow_control(uint32_t addr, uint32_t size, int state)
{
    switch (state) {
	case 0x00:
		mem_set_mem_state(addr, size, MEM_READ_INTERNAL | MEM_WRITE_INTERNAL);
		break;
	case 0x01:
		mem_set_mem_state(addr, size, MEM_READ_EXTANY | MEM_WRITE_INTERNAL);
		break;
	case 0x10:
		mem_set_mem_state(addr, size, MEM_READ_INTERNAL | MEM_WRITE_EXTANY);
		break;
	case 0x11:
		mem_set_mem_state(addr, size, MEM_READ_EXTANY | MEM_WRITE_EXTANY);
		break;
    }

    flushmmucache_nopc();
}


static void
rethink_shadow_mappings(cs8230_t *cs8230)
{
    int c;

    for (c = 0; c < 32; c++) {
	/* Addresses 40000-bffff in 16k blocks */
	if (cs8230->regs[0xa + (c >> 3)] & (1 << (c & 7)))
		mem_set_mem_state(0x40000 + (c << 14), 0x4000, MEM_READ_EXTERNAL | MEM_WRITE_EXTERNAL);		/* I/O channel */
	else
		mem_set_mem_state(0x40000 + (c << 14), 0x4000, MEM_READ_INTERNAL | MEM_WRITE_INTERNAL);		/* System board */
    }

    for (c = 0; c < 16; c++) {
	/* Addresses c0000-fffff in 16k blocks. System board ROM can be mapped here */
	if (cs8230->regs[0xe + (c >> 3)] & (1 << (c & 7)))
		mem_set_mem_state(0xc0000 + (c << 14), 0x4000, MEM_READ_EXTANY | MEM_WRITE_EXTANY);		/* I/O channel */
	else
		shadow_control(0xc0000 + (c << 14), 0x4000, (cs8230->regs[9] >> (3 - (c >> 2))) & 0x11);
    }
}


static uint8_t
cs8230_read(uint16_t port, void *p)
{
    cs8230_t *cs8230 = (cs8230_t *) p;
    uint8_t ret = 0xff;

    if (port & 1) {
	switch (cs8230->idx) {
		case 0x04:					/* 82C301 ID/version */
			ret = cs8230->regs[cs8230->idx] & ~0xe3;
			break;

		case 0x08:					/* 82C302 ID/Version */
			ret = cs8230->regs[cs8230->idx] & ~0xe0;
			break;

		case 0x05: case 0x06:				/* 82C301 registers */
		case 0x09: case 0x0a: case 0x0b: case 0x0c:	/* 82C302 registers */
		case 0x0d: case 0x0e: case 0x0f: 
		case 0x10: case 0x11: case 0x12: case 0x13:
		case 0x28: case 0x29: case 0x2a:
			ret = cs8230->regs[cs8230->idx];
			break;
	}
    }

    return ret;
}


static void
cs8230_write(uint16_t port, uint8_t val, void *p)
{
    cs8230_t *cs8230 = (cs8230_t *)p;

    if (!(port & 1))
	cs8230->idx = val;
    else {
	cs8230->regs[cs8230->idx] = val;
	switch (cs8230->idx) {
		case 0x09:								/* RAM/ROM Configuration in boot area */
		case 0x0a: case 0x0b: case 0x0c: case 0x0d: case 0x0e: case 0x0f:	/* Address maps */
			rethink_shadow_mappings(cs8230);
			break;
	}
    }
}


static void
cs8230_close(void *priv)
{
    cs8230_t *cs8230 = (cs8230_t *)priv;

    free(cs8230);
}


static void
*cs8230_init(const device_t *info)
{
    cs8230_t *cs8230 = (cs8230_t *)malloc(sizeof(cs8230_t));
    memset(cs8230, 0, sizeof(cs8230_t));

    io_sethandler(0x0022, 0x0002, cs8230_read, NULL, NULL, cs8230_write, NULL, NULL, cs8230);

    if (mem_size > 768) {
	mem_mapping_set_addr(&ram_mid_mapping, 0xa0000, mem_size > 1024 ? 0x60000 : 0x20000 + (mem_size - 768) * 1024);
	mem_mapping_set_exec(&ram_mid_mapping, ram + 0xa0000);
    }

    return cs8230;
}


const device_t cs8230_device = {
    "C&T CS8230 (386/AT)",
    0,
    0,
    cs8230_init, cs8230_close, NULL,
    { NULL }, NULL, NULL,
    NULL
};