59 строки
1.6 KiB
C
59 строки
1.6 KiB
C
/*
|
|
* This file is subject to the terms and conditions of the GNU General Public
|
|
* License. See the file "COPYING" in the main directory of this archive
|
|
* for more details.
|
|
*
|
|
* Copyright (C) 1998, 1999, 2003 by Ralf Baechle
|
|
*/
|
|
#ifndef _ASM_TIMEX_H
|
|
#define _ASM_TIMEX_H
|
|
|
|
#ifdef __KERNEL__
|
|
|
|
#include <asm/mipsregs.h>
|
|
|
|
/*
|
|
* This is the frequency of the timer used for Linux's timer interrupt.
|
|
* The value should be defined as accurate as possible or under certain
|
|
* circumstances Linux timekeeping might become inaccurate or fail.
|
|
*
|
|
* For many system the exact clockrate of the timer isn't known but due to
|
|
* the way this value is used we can get away with a wrong value as long
|
|
* as this value is:
|
|
*
|
|
* - a multiple of HZ
|
|
* - a divisor of the actual rate
|
|
*
|
|
* 500000 is a good such cheat value.
|
|
*
|
|
* The obscure number 1193182 is the same as used by the original i8254
|
|
* time in legacy PC hardware; the chip unfortunately also found in a
|
|
* bunch of MIPS systems. The last remaining user of the i8254 for the
|
|
* timer interrupt is the RM200; it's a very standard system so there is
|
|
* no reason to make this a separate architecture.
|
|
*/
|
|
|
|
#include <timex.h>
|
|
|
|
/*
|
|
* Standard way to access the cycle counter.
|
|
* Currently only used on SMP for scheduling.
|
|
*
|
|
* Only the low 32 bits are available as a continuously counting entity.
|
|
* But this only means we'll force a reschedule every 8 seconds or so,
|
|
* which isn't an evil thing.
|
|
*
|
|
* We know that all SMP capable CPUs have cycle counters.
|
|
*/
|
|
|
|
typedef unsigned int cycles_t;
|
|
|
|
static inline cycles_t get_cycles(void)
|
|
{
|
|
return read_c0_count();
|
|
}
|
|
|
|
#endif /* __KERNEL__ */
|
|
|
|
#endif /* _ASM_TIMEX_H */
|