mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-19 10:14:23 +08:00
7cb24b7003
Use DEC I/O ASIC's free-running counter for sched_clock source. This implementation will give high resolution cputime accounting. Acked-by: Maciej W. Rozycki <macro@linux-mips.org> Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com> Cc: linux-mips@linux-mips.org Cc: macro@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9482/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
75 lines
1.8 KiB
C
75 lines
1.8 KiB
C
/*
|
|
* DEC I/O ASIC's counter clocksource
|
|
*
|
|
* Copyright (C) 2008 Yoichi Yuasa <yuasa@linux-mips.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; either version 2 of the License, or
|
|
* (at your option) 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.
|
|
*/
|
|
#include <linux/clocksource.h>
|
|
#include <linux/sched_clock.h>
|
|
#include <linux/init.h>
|
|
|
|
#include <asm/ds1287.h>
|
|
#include <asm/time.h>
|
|
#include <asm/dec/ioasic.h>
|
|
#include <asm/dec/ioasic_addrs.h>
|
|
|
|
static cycle_t dec_ioasic_hpt_read(struct clocksource *cs)
|
|
{
|
|
return ioasic_read(IO_REG_FCTR);
|
|
}
|
|
|
|
static struct clocksource clocksource_dec = {
|
|
.name = "dec-ioasic",
|
|
.read = dec_ioasic_hpt_read,
|
|
.mask = CLOCKSOURCE_MASK(32),
|
|
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
|
|
};
|
|
|
|
static u64 notrace dec_ioasic_read_sched_clock(void)
|
|
{
|
|
return ioasic_read(IO_REG_FCTR);
|
|
}
|
|
|
|
int __init dec_ioasic_clocksource_init(void)
|
|
{
|
|
unsigned int freq;
|
|
u32 start, end;
|
|
int i = HZ / 8;
|
|
|
|
ds1287_timer_state();
|
|
while (!ds1287_timer_state())
|
|
;
|
|
|
|
start = dec_ioasic_hpt_read(&clocksource_dec);
|
|
|
|
while (i--)
|
|
while (!ds1287_timer_state())
|
|
;
|
|
|
|
end = dec_ioasic_hpt_read(&clocksource_dec);
|
|
|
|
freq = (end - start) * 8;
|
|
|
|
/* An early revision of the I/O ASIC didn't have the counter. */
|
|
if (!freq)
|
|
return -ENXIO;
|
|
|
|
printk(KERN_INFO "I/O ASIC clock frequency %dHz\n", freq);
|
|
|
|
clocksource_dec.rating = 200 + freq / 10000000;
|
|
clocksource_register_hz(&clocksource_dec, freq);
|
|
|
|
sched_clock_register(dec_ioasic_read_sched_clock, 32, freq);
|
|
|
|
return 0;
|
|
}
|