From 5dc99cc137b1815b67069a29dc29d5453069ba2f Mon Sep 17 00:00:00 2001 From: OBattler Date: Sun, 18 May 2025 08:37:02 +0200 Subject: [PATCH] SiS 85c46x and 471 - implement AT bus speed configuration. --- src/chipset/sis_85c4xx.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/src/chipset/sis_85c4xx.c b/src/chipset/sis_85c4xx.c index f715c5272..be5bd668e 100644 --- a/src/chipset/sis_85c4xx.c +++ b/src/chipset/sis_85c4xx.c @@ -15,6 +15,7 @@ * * Copyright 2019-2020 Miran Grca. */ +#include #include #include #include @@ -631,6 +632,41 @@ sis_85c4xx_out(uint16_t port, uint8_t val, void *priv) sis_85c4xx_recalcremap(dev); break; + case 0x10: + if (dev->reg_base == 0x50) { + double bus_clk; + + switch (val & 0xe0) { + default: + case 0x00: + bus_clk = 7159091.0; + break; + case 0x02: + bus_clk = cpu_busspeed / 10.0; + break; + case 0x04: + bus_clk = cpu_busspeed / 8.0; + break; + case 0x06: + bus_clk = cpu_busspeed / 6.0; + break; + case 0x80: + bus_clk = cpu_busspeed / 5.0; + break; + case 0xa0: + bus_clk = cpu_busspeed / 4.0; + break; + case 0xc0: + bus_clk = cpu_busspeed / 3.0; + break; + case 0xe0: + bus_clk = cpu_busspeed / 2.0; + break; + } + cpu_set_isa_speed((int) round(bus_clk)); + } + break; + case 0x13: if (dev->is_471 && (valxor & 0xf0)) { smram_disable(dev->smram); @@ -813,6 +849,9 @@ sis_85c4xx_reset(void *priv) dev->force_flush = 1; sis_85c4xx_recalcmapping(dev); + + if (dev->reg_base == 0x50) + cpu_set_isa_speed((int) round(7159091.0)); } static void