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86Box/src/video/clockgen/vid_clockgen_ics2494.c
TC1995 f0d93aa00c Video clock changes of the day (August 20th, 2025) 
Make the clocks of the ATI cards (pre-Mach64) more sane and precise (especially the Mach8/32).
2025-08-20 18:07:15 +02:00

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/*
* 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.
*
* ICS2494 clock generator emulation.
*
* Used by the AMI S3 924.
*
*
*
* Authors: Miran Grca, <mgrca8@gmail.com>
*
* Copyright 2020 Miran Grca.
*/
#include <stdarg.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#define HAVE_STDARG_H
#include <86box/86box.h>
#include <86box/device.h>
typedef struct ics2494_t {
float freq[16];
} ics2494_t;
#ifdef ENABLE_ICS2494_LOG
int ics2494_do_log = ENABLE_ICS2494_LOG;
static void
ics2494_log(const char *fmt, ...)
{
va_list ap;
if (ics2494_do_log) {
va_start(ap, fmt);
pclog_ex(fmt, ap);
va_end(ap);
}
}
#else
# define ics2494_log(fmt, ...)
#endif
/* Two consecutive byte-writes are NOT allowed. Furthermore an index
* written to 0x01CE is only usable ONCE! Note also that the setting of ATI
* extended registers (especially those with clock selection bits) should be
* bracketed by a sequencer reset.
*
* Boards prior to V5 use 4 crystals. Boards V5 and later use a clock
* generator chip. V3 and V4 boards differ when it comes to choosing clock
* frequencies.
*
* VGA Wonder V3/V4 Board Clock Frequencies
* R E G I S T E R S
* 1CE(*) 3C2 3C2 Frequency
* B2h/BEh
* Bit 6/4 Bit 3 Bit 2 (MHz)
* ------- ------- ------- -------
* 0 0 0 50.175
* 0 0 1 56.644
* 0 1 0 Spare 1
* 0 1 1 44.900
* 1 0 0 44.900
* 1 0 1 50.175
* 1 1 0 Spare 2
* 1 1 1 36.000
*
* (*): V3 uses index B2h, bit 6; V4 uses index BEh, bit 4
*
* V5, PLUS, XL and XL24 usually have an ATI 18810 clock generator chip, but
* some have an ATI 18811-0, and it's quite conceivable that some exist with
* ATI 18811-1's or ATI 18811-2's. Mach32 boards are known to use any one of
* these clock generators. The possibilities for Mach64 boards also include
* two different flavours of the newer 18818 chips. I have yet to figure out
* how BIOS initialization sets up the board for a particular set of
* frequencies. Mach32 and Mach64 boards also use a different dot clock
* ordering. ATI says there is no reliable way for the driver to determine
* which clock generator is on the board (their BIOS's are tailored to the
* board).
*
* VGA Wonder V5/PLUS/XL/XL24 Board Clock Frequencies
* R E G I S T E R S
* 1CE 1CE 3C2 3C2 Frequency
* B9h BEh (MHz) 18811-0 18811-1
* Bit 1 Bit 4 Bit 3 Bit 2 18810 18812-0 18811-2 18818-? 18818-?
* ------- ------- ------- ------- ------- ------- ------- ------- -------
* 0 0 0 0 30.240 30.240 135.000 (*3) (*3)
* 0 0 0 1 32.000 32.000 32.000 110.000 110.000
* 0 0 1 0 37.500 110.000 110.000 126.000 126.000
* 0 0 1 1 39.000 80.000 80.000 135.000 135.000
* 0 1 0 0 42.954 42.954 100.000 50.350 25.175
* 0 1 0 1 48.771 48.771 126.000 56.644 28.322
* 0 1 1 0 (*1) 92.400 92.400 63.000 31.500
* 0 1 1 1 36.000 36.000 36.000 72.000 36.000
* 1 0 0 0 40.000 39.910 39.910 (*3) (*3)
* 1 0 0 1 56.644 44.900 44.900 80.000 80.000
* 1 0 1 0 75.000 75.000 75.000 75.000 75.000
* 1 0 1 1 65.000 65.000 65.000 65.000 65.000
* 1 1 0 0 50.350 50.350 50.350 40.000 40.000
* 1 1 0 1 56.640 56.640 56.640 44.900 44.900
* 1 1 1 0 (*2) (*3) (*3) 49.500 49.500
* 1 1 1 1 44.900 44.900 44.900 50.000 50.000
*
* (*1) External 0 (supposedly 16.657 Mhz)
* (*2) External 1 (supposedly 28.322 MHz)
* (*3) This setting doesn't seem to generate anything
*
* Mach32 and Mach64 Board Clock Frequencies
* R E G I S T E R S
* 1CE 1CE 3C2 3C2 Frequency
* B9h BEh (MHz) 18811-0 18811-1
* Bit 1 Bit 4 Bit 3 Bit 2 18810 18812-0 18811-2 18818-? 18818-?
* ------- ------- ------- ------- ------- ------- ------- ------- -------
* 0 0 0 0 42.954 42.954 100.000 50.350 25.175
* 0 0 0 1 48.771 48.771 126.000 56.644 28.322
* 0 0 1 0 (*1) 92.400 92.400 63.000 31.500
* 0 0 1 1 36.000 36.000 36.000 72.000 36.000
* 0 1 0 0 30.240 30.240 135.000 (*3) (*3)
* 0 1 0 1 32.000 32.000 32.000 110.000 110.000
* 0 1 1 0 37.500 110.000 110.000 126.000 126.000
* 0 1 1 1 39.000 80.000 80.000 135.000 135.000
* 1 0 0 0 50.350 50.350 50.350 40.000 40.000
* 1 0 0 1 56.640 56.640 56.640 44.900 44.900
* 1 0 1 0 (*2) (*3) (*3) 49.500 49.500
* 1 0 1 1 44.900 44.900 44.900 50.000 50.000
* 1 1 0 0 40.000 39.910 39.910 (*3) (*3)
* 1 1 0 1 56.644 44.900 44.900 80.000 80.000
* 1 1 1 0 75.000 75.000 75.000 75.000 75.000
* 1 1 1 1 65.000 65.000 65.000 65.000 65.000
*
* (*1) External 0 (supposedly 16.657 Mhz)
* (*2) External 1 (supposedly 28.322 MHz)
* (*3) This setting doesn't seem to generate anything
*
* Note that, to reduce confusion, this driver masks out the different clock
* ordering.
*
* For all boards, these frequencies can be divided by 1, 2, 3 or 4.
*
* Register 1CE, index B8h
* Bit 7 Bit 6
* ------- -------
* 0 0 Divide by 1
* 0 1 Divide by 2
* 1 0 Divide by 3
* 1 1 Divide by 4
*
* There is some question as to whether or not bit 1 of index 0xB9 can
* be used for clock selection on a V4 board. This driver makes it
* available only if the "undocumented_clocks" option (itself
* undocumented :-)) is specified in XF86Config.
*
* Also it appears that bit 0 of index 0xB9 can also be used for clock
* selection on some boards. It is also only available under XF86Config
* option "undocumented_clocks".
*/
float
ics2494_getclock(int clock, void *priv)
{
const ics2494_t *ics2494 = (ics2494_t *) priv;
if (clock > 15)
clock = 15;
return ics2494->freq[clock];
}
static void *
ics2494_init(const device_t *info)
{
ics2494_t *ics2494 = (ics2494_t *) malloc(sizeof(ics2494_t));
memset(ics2494, 0, sizeof(ics2494_t));
switch (info->local) {
case 0:
/* ATI 18810 for ATI 28800 */
ics2494->freq[0] = 30240000.0;
ics2494->freq[1] = 32000000.0;
ics2494->freq[2] = 37500000.0;
ics2494->freq[3] = 39000000.0;
ics2494->freq[4] = 42954000.0;
ics2494->freq[5] = 48771000.0;
ics2494->freq[6] = 0.0;
ics2494->freq[7] = 36000000.0;
ics2494->freq[8] = 40000000.0;
ics2494->freq[9] = 56644000.0;
ics2494->freq[10] = 75000000.0;
ics2494->freq[11] = 65000000.0;
ics2494->freq[12] = 50350000.0;
ics2494->freq[13] = 56640000.0;
ics2494->freq[14] = 0.0;
ics2494->freq[15] = 44900000.0;
break;
case 1:
/* ATI 18811-0/ATI 18812-0 for ATI 28800 */
ics2494->freq[0] = 42950000.0;
ics2494->freq[1] = 48770000.0;
ics2494->freq[2] = 92400000.0;
ics2494->freq[3] = 36000000.0;
ics2494->freq[4] = 50350000.0;
ics2494->freq[5] = 56640000.0;
ics2494->freq[7] = 44900000.0;
ics2494->freq[8] = 30240000.0;
ics2494->freq[9] = 32000000.0;
ics2494->freq[10] = 110000000.0;
ics2494->freq[11] = 80000000.0;
ics2494->freq[12] = 39910000.0;
ics2494->freq[13] = 44900000.0;
ics2494->freq[14] = 75000000.0;
ics2494->freq[15] = 65000000.0;
break;
case 2:
/* ATI 18811-1/ATI 18811-2 for ATI 28800 */
ics2494->freq[0] = 100000000.0;
ics2494->freq[1] = 126000000.0;
ics2494->freq[2] = 92400000.0;
ics2494->freq[3] = 36000000.0;
ics2494->freq[4] = 50350000.0;
ics2494->freq[5] = 56640000.0;
ics2494->freq[7] = 44900000.0;
ics2494->freq[8] = 135000000.0;
ics2494->freq[9] = 32000000.0;
ics2494->freq[10] = 110000000.0;
ics2494->freq[11] = 80000000.0;
ics2494->freq[12] = 39910000.0;
ics2494->freq[13] = 44900000.0;
ics2494->freq[14] = 75000000.0;
ics2494->freq[15] = 65000000.0;
break;
case 100:
/* ATI 18810 for ATI Mach32 */
ics2494->freq[0] = 42954000.0;
ics2494->freq[1] = 48771000.0;
ics2494->freq[2] = 0.0;
ics2494->freq[3] = 36000000.0;
ics2494->freq[4] = 30240000.0;
ics2494->freq[5] = 32000000.0;
ics2494->freq[6] = 37500000.0;
ics2494->freq[7] = 39000000.0;
ics2494->freq[8] = 50350000.0;
ics2494->freq[9] = 56640000.0;
ics2494->freq[10] = 0.0;
ics2494->freq[11] = 44900000.0;
ics2494->freq[12] = 40000000.0;
ics2494->freq[13] = 56644000.0;
ics2494->freq[14] = 75000000.0;
ics2494->freq[15] = 65000000.0;
break;
case 101:
/* ATI 18811-0/ATI 18812-0 for ATI Mach32 */
ics2494->freq[0] = 42954000.0;
ics2494->freq[1] = 48771000.0;
ics2494->freq[2] = 92400000.0;
ics2494->freq[3] = 36000000.0;
ics2494->freq[4] = 30240000.0;
ics2494->freq[5] = 32000000.0;
ics2494->freq[6] = 110000000.0;
ics2494->freq[7] = 80000000.0;
ics2494->freq[8] = 50350000.0;
ics2494->freq[9] = 56640000.0;
ics2494->freq[10] = 0.0;
ics2494->freq[11] = 44900000.0;
ics2494->freq[12] = 39910000.0;
ics2494->freq[13] = 44900000.0;
ics2494->freq[14] = 75000000.0;
ics2494->freq[15] = 65000000.0;
break;
case 102:
/* ATI 18811-1/ATI 18811-2 for ATI Mach32 */
ics2494->freq[0] = 100000000.0;
ics2494->freq[1] = 126000000.0;
ics2494->freq[2] = 92400000.0;
ics2494->freq[3] = 36000000.0;
ics2494->freq[4] = 50350000.0;
ics2494->freq[5] = 56640000.0;
ics2494->freq[7] = 44900000.0;
ics2494->freq[8] = 135000000.0;
ics2494->freq[9] = 32000000.0;
ics2494->freq[10] = 110000000.0;
ics2494->freq[11] = 80000000.0;
ics2494->freq[12] = 39910000.0;
ics2494->freq[13] = 44900000.0;
ics2494->freq[14] = 75000000.0;
ics2494->freq[15] = 65000000.0;
break;
case 305:
/* ICS2494A(N)-205 for S3 86C924 */
ics2494->freq[0x0] = 25175000.0;
ics2494->freq[0x1] = 28322000.0;
ics2494->freq[0x2] = 40000000.0;
ics2494->freq[0x3] = 0.0;
ics2494->freq[0x4] = 50000000.0;
ics2494->freq[0x5] = 77000000.0;
ics2494->freq[0x6] = 36000000.0;
ics2494->freq[0x7] = 44889000.0;
ics2494->freq[0x8] = 130000000.0;
ics2494->freq[0x9] = 120000000.0;
ics2494->freq[0xa] = 80000000.0;
ics2494->freq[0xb] = 31500000.0;
ics2494->freq[0xc] = 110000000.0;
ics2494->freq[0xd] = 65000000.0;
ics2494->freq[0xe] = 75000000.0;
ics2494->freq[0xf] = 94500000.0;
break;
default:
break;
}
return ics2494;
}
static void
ics2494_close(void *priv)
{
ics2494_t *ics2494 = (ics2494_t *) priv;
if (ics2494)
free(ics2494);
}
const device_t ics2494an_305_device = {
.name = "ICS2494AN-305 Clock Generator",
.internal_name = "ics2494an_305",
.flags = 0,
.local = 305,
.init = ics2494_init,
.close = ics2494_close,
.reset = NULL,
.available = NULL,
.speed_changed = NULL,
.force_redraw = NULL,
.config = NULL
};
const device_t ati18810_28800_device = {
.name = "ATI 18810 (ATI 28800) Clock Generator",
.internal_name = "ati18810_28800",
.flags = 0,
.local = 0,
.init = ics2494_init,
.close = ics2494_close,
.reset = NULL,
.available = NULL,
.speed_changed = NULL,
.force_redraw = NULL,
.config = NULL
};
const device_t ati18811_0_28800_device = {
.name = "ATI 18811-0 (ATI 28800) Clock Generator",
.internal_name = "ati18811_0_28800",
.flags = 0,
.local = 1,
.init = ics2494_init,
.close = ics2494_close,
.reset = NULL,
.available = NULL,
.speed_changed = NULL,
.force_redraw = NULL,
.config = NULL
};
const device_t ati18811_1_28800_device = {
.name = "ATI 18811-1 (ATI 28800) Clock Generator",
.internal_name = "ati18811_1_28800",
.flags = 0,
.local = 2,
.init = ics2494_init,
.close = ics2494_close,
.reset = NULL,
.available = NULL,
.speed_changed = NULL,
.force_redraw = NULL,
.config = NULL
};
const device_t ati18810_mach32_device = {
.name = "ATI 18810 (ATI Mach32) Clock Generator",
.internal_name = "ati18810_mach32",
.flags = 0,
.local = 100,
.init = ics2494_init,
.close = ics2494_close,
.reset = NULL,
.available = NULL,
.speed_changed = NULL,
.force_redraw = NULL,
.config = NULL
};
const device_t ati18811_0_mach32_device = {
.name = "ATI 18811-0 (ATI Mach32) Clock Generator",
.internal_name = "ati18811_0_mach32",
.flags = 0,
.local = 101,
.init = ics2494_init,
.close = ics2494_close,
.reset = NULL,
.available = NULL,
.speed_changed = NULL,
.force_redraw = NULL,
.config = NULL
};
const device_t ati18811_1_mach32_device = {
.name = "ATI 18811-1 (ATI Mach32) Clock Generator",
.internal_name = "ati18811_1_mach32",
.flags = 0,
.local = 102,
.init = ics2494_init,
.close = ics2494_close,
.reset = NULL,
.available = NULL,
.speed_changed = NULL,
.force_redraw = NULL,
.config = NULL
};
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