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

   1/*
   2 *  linux/arch/arm/kernel/time.c
   3 *
   4 *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   5 *  Modifications for ARM (C) 1994-2001 Russell King
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 *
  11 *  This file contains the ARM-specific time handling details:
  12 *  reading the RTC at bootup, etc...
  13 */
  14#include <linux/clk-provider.h>
  15#include <linux/clocksource.h>
  16#include <linux/errno.h>
  17#include <linux/export.h>
  18#include <linux/init.h>
  19#include <linux/interrupt.h>
  20#include <linux/irq.h>
  21#include <linux/kernel.h>
  22#include <linux/profile.h>
  23#include <linux/sched.h>
  24#include <linux/sched_clock.h>
  25#include <linux/smp.h>
  26#include <linux/time.h>
  27#include <linux/timex.h>
  28#include <linux/timer.h>
  29
  30#include <asm/mach/arch.h>
  31#include <asm/mach/time.h>
  32#include <asm/stacktrace.h>
  33#include <asm/thread_info.h>
  34
  35#if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \
  36    defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE)
  37/* this needs a better home */
  38DEFINE_SPINLOCK(rtc_lock);
  39EXPORT_SYMBOL(rtc_lock);
  40#endif  /* pc-style 'CMOS' RTC support */
  41
  42/* change this if you have some constant time drift */
  43#define USECS_PER_JIFFY (1000000/HZ)
  44
  45#ifdef CONFIG_SMP
  46unsigned long profile_pc(struct pt_regs *regs)
  47{
  48        struct stackframe frame;
  49
  50        if (!in_lock_functions(regs->ARM_pc))
  51                return regs->ARM_pc;
  52
  53        arm_get_current_stackframe(regs, &frame);
  54        do {
  55                int ret = unwind_frame(&frame);
  56                if (ret < 0)
  57                        return 0;
  58        } while (in_lock_functions(frame.pc));
  59
  60        return frame.pc;
  61}
  62EXPORT_SYMBOL(profile_pc);
  63#endif
  64
  65#ifndef CONFIG_GENERIC_CLOCKEVENTS
  66/*
  67 * Kernel system timer support.
  68 */
  69void timer_tick(void)
  70{
  71        profile_tick(CPU_PROFILING);
  72        xtime_update(1);
  73#ifndef CONFIG_SMP
  74        update_process_times(user_mode(get_irq_regs()));
  75#endif
  76}
  77#endif
  78
  79static void dummy_clock_access(struct timespec64 *ts)
  80{
  81        ts->tv_sec = 0;
  82        ts->tv_nsec = 0;
  83}
  84
  85static clock_access_fn __read_persistent_clock = dummy_clock_access;
  86static clock_access_fn __read_boot_clock = dummy_clock_access;;
  87
  88void read_persistent_clock64(struct timespec64 *ts)
  89{
  90        __read_persistent_clock(ts);
  91}
  92
  93void read_boot_clock64(struct timespec64 *ts)
  94{
  95        __read_boot_clock(ts);
  96}
  97
  98int __init register_persistent_clock(clock_access_fn read_boot,
  99                                     clock_access_fn read_persistent)
 100{
 101        /* Only allow the clockaccess functions to be registered once */
 102        if (__read_persistent_clock == dummy_clock_access &&
 103            __read_boot_clock == dummy_clock_access) {
 104                if (read_boot)
 105                        __read_boot_clock = read_boot;
 106                if (read_persistent)
 107                        __read_persistent_clock = read_persistent;
 108
 109                return 0;
 110        }
 111
 112        return -EINVAL;
 113}
 114
 115void __init time_init(void)
 116{
 117        if (machine_desc->init_time) {
 118                machine_desc->init_time();
 119        } else {
 120#ifdef CONFIG_COMMON_CLK
 121                of_clk_init(NULL);
 122#endif
 123                clocksource_of_init();
 124        }
 125}
 126