2 * Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
20 FILE_LICENCE ( GPL2_OR_LATER );
28 #include <ipxe/timer.h>
33 * Get current system time in ticks
35 * @ret ticks Current time, in ticks
37 * Use direct memory access to BIOS variables, longword 0040:006C
38 * (ticks today) and byte 0040:0070 (midnight crossover flag) instead
39 * of calling timeofday BIOS interrupt.
41 static unsigned long bios_currticks ( void ) {
46 /* Re-enable interrupts so that the timer interrupt can occur */
47 __asm__ __volatile__ ( "sti\n\t"
52 get_real ( ticks, BDA_SEG, 0x006c );
53 get_real ( midnight, BDA_SEG, 0x0070 );
57 put_real ( midnight, BDA_SEG, 0x0070 );
61 return ( days + ticks );
64 PROVIDE_TIMER_INLINE ( pcbios, udelay );
65 PROVIDE_TIMER ( pcbios, currticks, bios_currticks );
66 PROVIDE_TIMER_INLINE ( pcbios, ticks_per_sec );