/* * Copyright (C) 2006-2023 Oracle and/or its affiliates. * * This file is part of VirtualBox base platform packages, as * available from https://www.virtualbox.org. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation, in version 3 of the * License. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see . * * SPDX-License-Identifier: GPL-3.0-only * -------------------------------------------------------------------- * * This code is based on: * * ROM BIOS for use with Bochs/Plex86/QEMU emulation environment * * Copyright (C) 2002 MandrakeSoft S.A. * * MandrakeSoft S.A. * 43, rue d'Aboukir * 75002 Paris - France * http://www.linux-mandrake.com/ * http://www.mandrakesoft.com/ * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * */ /* * Oracle LGPL Disclaimer: For the avoidance of doubt, except that if any license choice * other than GPL or LGPL is available it will apply instead, Oracle elects to use only * the Lesser General Public License version 2.1 (LGPLv2) at this time for any software where * a choice of LGPL license versions is made available with the language indicating * that LGPLv2 or any later version may be used, or where a choice of which version * of the LGPL is applied is otherwise unspecified. */ #include #include "biosint.h" #include "inlines.h" #if DEBUG_INT1A # define BX_DEBUG_INT1A(...) BX_DEBUG(__VA_ARGS__) #else # define BX_DEBUG_INT1A(...) #endif // for access to RAM area which is used by interrupt vectors // and BIOS Data Area typedef struct { uint8_t filler1[0x400]; uint8_t filler2[0x6c]; uint16_t ticks_low; uint16_t ticks_high; uint8_t midnight_flag; } bios_data_t; #define BiosData ((bios_data_t __far *) 0) void init_rtc(void) { outb_cmos(0x0a, 0x26); outb_cmos(0x0b, 0x02); inb_cmos(0x0c); inb_cmos(0x0d); } bx_bool rtc_updating(void) { // This function checks to see if the update-in-progress bit // is set in CMOS Status Register A. If not, it returns 0. // If it is set, it tries to wait until there is a transition // to 0, and will return 0 if such a transition occurs. A 1 // is returned only after timing out. The maximum period // that this bit should be set is constrained to 244useconds. // The count I use below guarantees coverage or more than // this time, with any reasonable IPS setting. uint16_t iter; iter = 25000; while (--iter != 0) { if ( (inb_cmos(0x0a) & 0x80) == 0 ) return 0; } return 1; // update-in-progress never transitioned to 0 } extern void eoi_both_pics(void); /* in assembly code */ #pragma aux eoi_both_pics "*"; void call_int_4a(void); #pragma aux call_int_4a = "int 4Ah"; void BIOSCALL int70_function(pusha_regs_t regs, uint16_t ds, uint16_t es, iret_addr_t iret_addr) { // INT 70h: IRQ 8 - CMOS RTC interrupt from periodic or alarm modes uint8_t registerB = 0, registerC = 0; // Check which modes are enabled and have occurred. registerB = inb_cmos( 0xB ); registerC = inb_cmos( 0xC ); if( ( registerB & 0x60 ) != 0 ) { if( ( registerC & 0x20 ) != 0 ) { // Handle Alarm Interrupt. int_enable(); call_int_4a(); int_disable(); } if( ( registerC & 0x40 ) != 0 ) { // Handle Periodic Interrupt. if( read_byte( 0x40, 0xA0 ) != 0 ) { // Wait Interval (Int 15, AH=83 or AH=86) active. uint32_t time; time = read_dword( 0x40, 0x9C ); // Time left in microseconds. if( time < 0x3D1 ) { // Done waiting. uint16_t segment, offset; segment = read_word( 0x40, 0x98 ); offset = read_word( 0x40, 0x9A ); write_byte( 0x40, 0xA0, 0 ); // Turn off status byte. outb_cmos( 0xB, registerB & 0x37 ); // Clear the Periodic Interrupt. write_byte( segment, offset, read_byte(segment, offset) | 0x80 ); // Write to specified flag byte. } else { // Continue waiting. time -= 0x3D1; write_dword( 0x40, 0x9C, time ); } } } } eoi_both_pics(); } /// @todo the coding style WRT register access is totally inconsistent // in the following routines void BIOSCALL int1a_function(pusha_regs_t regs, uint16_t ds, uint16_t es, iret_addr_t iret_addr) { uint8_t val8; BX_DEBUG_INT1A("int1a: AX=%04x BX=%04x CX=%04x DX=%04x DS=%04x\n", regs.u.r16.ax, regs.u.r16.bx, regs.u.r16.cx, regs.u.r16.dx, ds); int_enable(); switch (regs.u.r8.ah) { case 0: // get current clock count int_disable(); regs.u.r16.cx = BiosData->ticks_high; regs.u.r16.dx = BiosData->ticks_low; regs.u.r8.al = BiosData->midnight_flag; BiosData->midnight_flag = 0; // reset flag int_enable(); // AH already 0 ClearCF(iret_addr.flags); // OK break; case 1: // Set Current Clock Count int_disable(); BiosData->ticks_high = regs.u.r16.cx; BiosData->ticks_low = regs.u.r16.dx; BiosData->midnight_flag = 0; // reset flag int_enable(); regs.u.r8.ah = 0; ClearCF(iret_addr.flags); // OK break; case 2: // Read CMOS Time if (rtc_updating()) { SetCF(iret_addr.flags); break; } regs.u.r8.dh = inb_cmos(0x00); // Seconds regs.u.r8.cl = inb_cmos(0x02); // Minutes regs.u.r8.ch = inb_cmos(0x04); // Hours regs.u.r8.dl = inb_cmos(0x0b) & 0x01; // Stat Reg B regs.u.r8.ah = 0; regs.u.r8.al = regs.u.r8.ch; ClearCF(iret_addr.flags); // OK break; case 3: // Set CMOS Time // Using a debugger, I notice the following masking/setting // of bits in Status Register B, by setting Reg B to // a few values and getting its value after INT 1A was called. // // try#1 try#2 try#3 // before 1111 1101 0111 1101 0000 0000 // after 0110 0010 0110 0010 0000 0010 // // Bit4 in try#1 flipped in hardware (forced low) due to bit7=1 // My assumption: RegB = ((RegB & 01100000b) | 00000010b) if (rtc_updating()) { init_rtc(); // fall through as if an update were not in progress } outb_cmos(0x00, regs.u.r8.dh); // Seconds outb_cmos(0x02, regs.u.r8.cl); // Minutes outb_cmos(0x04, regs.u.r8.ch); // Hours // Set Daylight Savings time enabled bit to requested value val8 = (inb_cmos(0x0b) & 0x60) | 0x02 | (regs.u.r8.dl & 0x01); // (reg B already selected) outb_cmos(0x0b, val8); regs.u.r8.ah = 0; regs.u.r8.al = val8; // val last written to Reg B ClearCF(iret_addr.flags); // OK break; case 4: // Read CMOS Date regs.u.r8.ah = 0; if (rtc_updating()) { SetCF(iret_addr.flags); break; } regs.u.r8.cl = inb_cmos(0x09); // Year regs.u.r8.dh = inb_cmos(0x08); // Month regs.u.r8.dl = inb_cmos(0x07); // Day of Month regs.u.r8.ch = inb_cmos(0x32); // Century regs.u.r8.al = regs.u.r8.ch; ClearCF(iret_addr.flags); // OK break; case 5: // Set CMOS Date // Using a debugger, I notice the following masking/setting // of bits in Status Register B, by setting Reg B to // a few values and getting its value after INT 1A was called. // // try#1 try#2 try#3 try#4 // before 1111 1101 0111 1101 0000 0010 0000 0000 // after 0110 1101 0111 1101 0000 0010 0000 0000 // // Bit4 in try#1 flipped in hardware (forced low) due to bit7=1 // My assumption: RegB = (RegB & 01111111b) if (rtc_updating()) { init_rtc(); SetCF(iret_addr.flags); break; } outb_cmos(0x09, regs.u.r8.cl); // Year outb_cmos(0x08, regs.u.r8.dh); // Month outb_cmos(0x07, regs.u.r8.dl); // Day of Month outb_cmos(0x32, regs.u.r8.ch); // Century val8 = inb_cmos(0x0b) & 0x7f; // clear halt-clock bit outb_cmos(0x0b, val8); regs.u.r8.ah = 0; regs.u.r8.al = val8; // AL = val last written to Reg B ClearCF(iret_addr.flags); // OK break; case 6: // Set Alarm Time in CMOS // Using a debugger, I notice the following masking/setting // of bits in Status Register B, by setting Reg B to // a few values and getting its value after INT 1A was called. // // try#1 try#2 try#3 // before 1101 1111 0101 1111 0000 0000 // after 0110 1111 0111 1111 0010 0000 // // Bit4 in try#1 flipped in hardware (forced low) due to bit7=1 // My assumption: RegB = ((RegB & 01111111b) | 00100000b) val8 = inb_cmos(0x0b); // Get Status Reg B regs.u.r16.ax = 0; if (val8 & 0x20) { // Alarm interrupt enabled already SetCF(iret_addr.flags); // Error: alarm in use break; } if (rtc_updating()) { init_rtc(); // fall through as if an update were not in progress } outb_cmos(0x01, regs.u.r8.dh); // Seconds alarm outb_cmos(0x03, regs.u.r8.cl); // Minutes alarm outb_cmos(0x05, regs.u.r8.ch); // Hours alarm outb(0xa1, inb(0xa1) & 0xfe); // enable IRQ 8 // enable Status Reg B alarm bit, clear halt clock bit outb_cmos(0x0b, (val8 & 0x7f) | 0x20); ClearCF(iret_addr.flags); // OK break; case 7: // Turn off Alarm // Using a debugger, I notice the following masking/setting // of bits in Status Register B, by setting Reg B to // a few values and getting its value after INT 1A was called. // // try#1 try#2 try#3 try#4 // before 1111 1101 0111 1101 0010 0000 0010 0010 // after 0100 0101 0101 0101 0000 0000 0000 0010 // // Bit4 in try#1 flipped in hardware (forced low) due to bit7=1 // My assumption: RegB = (RegB & 01010111b) val8 = inb_cmos(0x0b); // Get Status Reg B // clear clock-halt bit, disable alarm bit outb_cmos(0x0b, val8 & 0x57); // disable alarm bit regs.u.r8.ah = 0; regs.u.r8.al = val8; // val last written to Reg B ClearCF(iret_addr.flags); // OK break; default: BX_DEBUG_INT1A("int1a: AX=%04x unsupported\n", regs.u.r16.ax); SetCF(iret_addr.flags); // Unsupported } }