| /* |
| * Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>. |
| * |
| * 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; either version 2 of the |
| * License, or any later version. |
| * |
| * 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, write to the Free Software |
| * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| */ |
| |
| FILE_LICENCE ( GPL2_OR_LATER ); |
| |
| /** @file |
| * |
| * BIOS timer |
| * |
| */ |
| |
| #include <gpxe/timer.h> |
| #include <realmode.h> |
| #include <bios.h> |
| |
| /** |
| * Get current system time in ticks |
| * |
| * @ret ticks Current time, in ticks |
| * |
| * Use direct memory access to BIOS variables, longword 0040:006C |
| * (ticks today) and byte 0040:0070 (midnight crossover flag) instead |
| * of calling timeofday BIOS interrupt. |
| */ |
| static unsigned long bios_currticks ( void ) { |
| static int days = 0; |
| uint32_t ticks; |
| uint8_t midnight; |
| |
| /* Re-enable interrupts so that the timer interrupt can occur */ |
| __asm__ __volatile__ ( REAL_CODE ( "sti\n\t" |
| "nop\n\t" |
| "nop\n\t" |
| "cli\n\t" ) : : ); |
| |
| get_real ( ticks, BDA_SEG, 0x006c ); |
| get_real ( midnight, BDA_SEG, 0x0070 ); |
| |
| if ( midnight ) { |
| midnight = 0; |
| put_real ( midnight, BDA_SEG, 0x0070 ); |
| days += 0x1800b0; |
| } |
| |
| return ( days + ticks ); |
| } |
| |
| PROVIDE_TIMER_INLINE ( pcbios, udelay ); |
| PROVIDE_TIMER ( pcbios, currticks, bios_currticks ); |
| PROVIDE_TIMER_INLINE ( pcbios, ticks_per_sec ); |