LXR linux/arch/arm64/kernel/time.c

   1/*
   2 * Based on arch/arm/kernel/time.c
   3 *
   4 * Copyright (C) 1991, 1992, 1995  Linus Torvalds
   5 * Modifications for ARM (C) 1994-2001 Russell King
   6 * Copyright (C) 2012 ARM Ltd.
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 *
  12 * This program is distributed in the hope that it will be useful,
  13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21#include <linux/export.h>
  22#include <linux/kernel.h>
  23#include <linux/interrupt.h>
  24#include <linux/time.h>
  25#include <linux/init.h>
  26#include <linux/sched.h>
  27#include <linux/smp.h>
  28#include <linux/timex.h>
  29#include <linux/errno.h>
  30#include <linux/profile.h>
  31#include <linux/syscore_ops.h>
  32#include <linux/timer.h>
  33#include <linux/irq.h>
  34#include <linux/delay.h>
  35
  36#include <clocksource/arm_arch_timer.h>
  37
  38#include <asm/thread_info.h>
  39#include <asm/stacktrace.h>
  40
  41#ifdef CONFIG_SMP
  42unsigned long profile_pc(struct pt_regs *regs)
  43{
  44        struct stackframe frame;
  45
  46        if (!in_lock_functions(regs->pc))
  47                return regs->pc;
  48
  49        frame.fp = regs->regs[29];
  50        frame.sp = regs->sp;
  51        frame.pc = regs->pc;
  52        do {
  53                int ret = unwind_frame(&frame);
  54                if (ret < 0)
  55                        return 0;
  56        } while (in_lock_functions(frame.pc));
  57
  58        return frame.pc;
  59}
  60EXPORT_SYMBOL(profile_pc);
  61#endif
  62
  63static u64 sched_clock_mult __read_mostly;
  64
  65unsigned long long notrace sched_clock(void)
  66{
  67        return arch_timer_read_counter() * sched_clock_mult;
  68}
  69
  70int read_current_timer(unsigned long *timer_value)
  71{
  72        *timer_value = arch_timer_read_counter();
  73        return 0;
  74}
  75
  76void __init time_init(void)
  77{
  78        u32 arch_timer_rate;
  79
  80        if (arch_timer_init())
  81                panic("Unable to initialise architected timer.\n");
  82
  83        arch_timer_rate = arch_timer_get_rate();
  84
  85        /* Cache the sched_clock multiplier to save a divide in the hot path. */
  86        sched_clock_mult = NSEC_PER_SEC / arch_timer_rate;
  87
  88        /* Calibrate the delay loop directly */
  89        lpj_fine = arch_timer_rate / HZ;
  90}
  91