linux/arch/arm64/kernel/time.c

91 lines
2.2 KiB
C

/*
* Based on arch/arm/kernel/time.c
*
* Copyright (C) 1991, 1992, 1995 Linus Torvalds
* Modifications for ARM (C) 1994-2001 Russell King
* Copyright (C) 2012 ARM Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 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 <http://www.gnu.org/licenses/>.
*/
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/timex.h>
#include <linux/errno.h>
#include <linux/profile.h>
#include <linux/syscore_ops.h>
#include <linux/timer.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <clocksource/arm_arch_timer.h>
#include <asm/thread_info.h>
#include <asm/stacktrace.h>
#ifdef CONFIG_SMP
unsigned long profile_pc(struct pt_regs *regs)
{
struct stackframe frame;
if (!in_lock_functions(regs->pc))
return regs->pc;
frame.fp = regs->regs[29];
frame.sp = regs->sp;
frame.pc = regs->pc;
do {
int ret = unwind_frame(&frame);
if (ret < 0)
return 0;
} while (in_lock_functions(frame.pc));
return frame.pc;
}
EXPORT_SYMBOL(profile_pc);
#endif
static u64 sched_clock_mult __read_mostly;
unsigned long long notrace sched_clock(void)
{
return arch_timer_read_counter() * sched_clock_mult;
}
int read_current_timer(unsigned long *timer_value)
{
*timer_value = arch_timer_read_counter();
return 0;
}
void __init time_init(void)
{
u32 arch_timer_rate;
if (arch_timer_init())
panic("Unable to initialise architected timer.\n");
arch_timer_rate = arch_timer_get_rate();
/* Cache the sched_clock multiplier to save a divide in the hot path. */
sched_clock_mult = NSEC_PER_SEC / arch_timer_rate;
/* Calibrate the delay loop directly */
lpj_fine = arch_timer_rate / HZ;
}