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#include <linux/clocksource.h>
  36
  37#include <clocksource/arm_arch_timer.h>
  38
  39#include <asm/thread_info.h>
  40#include <asm/stacktrace.h>
  41
  42#ifdef CONFIG_SMP
  43unsigned long profile_pc(struct pt_regs *regs)
  44{
  45        struct stackframe frame;
  46
  47        if (!in_lock_functions(regs->pc))
  48                return regs->pc;
  49
  50        frame.fp = regs->regs[29];
  51        frame.sp = regs->sp;
  52        frame.pc = regs->pc;
  53        do {
  54                int ret = unwind_frame(&frame);
  55                if (ret < 0)
  56                        return 0;
  57        } while (in_lock_functions(frame.pc));
  58
  59        return frame.pc;
  60}
  61EXPORT_SYMBOL(profile_pc);
  62#endif
  63
  64static u64 sched_clock_mult __read_mostly;
  65
  66unsigned long long notrace sched_clock(void)
  67{
  68        return arch_timer_read_counter() * sched_clock_mult;
  69}
  70
  71void __init time_init(void)
  72{
  73        u32 arch_timer_rate;
  74
  75        clocksource_of_init();
  76
  77        arch_timer_rate = arch_timer_get_rate();
  78        if (!arch_timer_rate)
  79                panic("Unable to initialise architected timer.\n");
  80
  81        /* Cache the sched_clock multiplier to save a divide in the hot path. */
  82        sched_clock_mult = NSEC_PER_SEC / arch_timer_rate;
  83
  84        /* Calibrate the delay loop directly */
  85        lpj_fine = arch_timer_rate / HZ;
  86}
  87