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/export.h>
  15#include <linux/kernel.h>
  16#include <linux/interrupt.h>
  17#include <linux/time.h>
  18#include <linux/init.h>
  19#include <linux/sched.h>
  20#include <linux/smp.h>
  21#include <linux/timex.h>
  22#include <linux/errno.h>
  23#include <linux/profile.h>
  24#include <linux/timer.h>
  25#include <linux/clocksource.h>
  26#include <linux/irq.h>
  27
  28#include <asm/thread_info.h>
  29#include <asm/sched_clock.h>
  30#include <asm/stacktrace.h>
  31#include <asm/mach/arch.h>
  32#include <asm/mach/time.h>
  33
  34#if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \
  35    defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE)
  36/* this needs a better home */
  37DEFINE_SPINLOCK(rtc_lock);
  38EXPORT_SYMBOL(rtc_lock);
  39#endif  /* pc-style 'CMOS' RTC support */
  40
  41/* change this if you have some constant time drift */
  42#define USECS_PER_JIFFY (1000000/HZ)
  43
  44#ifdef CONFIG_SMP
  45unsigned long profile_pc(struct pt_regs *regs)
  46{
  47        struct stackframe frame;
  48
  49        if (!in_lock_functions(regs->ARM_pc))
  50                return regs->ARM_pc;
  51
  52        frame.fp = regs->ARM_fp;
  53        frame.sp = regs->ARM_sp;
  54        frame.lr = regs->ARM_lr;
  55        frame.pc = regs->ARM_pc;
  56        do {
  57                int ret = unwind_frame(&frame);
  58                if (ret < 0)
  59                        return 0;
  60        } while (in_lock_functions(frame.pc));
  61
  62        return frame.pc;
  63}
  64EXPORT_SYMBOL(profile_pc);
  65#endif
  66
  67#ifndef CONFIG_GENERIC_CLOCKEVENTS
  68/*
  69 * Kernel system timer support.
  70 */
  71void timer_tick(void)
  72{
  73        profile_tick(CPU_PROFILING);
  74        xtime_update(1);
  75#ifndef CONFIG_SMP
  76        update_process_times(user_mode(get_irq_regs()));
  77#endif
  78}
  79#endif
  80
  81static void dummy_clock_access(struct timespec *ts)
  82{
  83        ts->tv_sec = 0;
  84        ts->tv_nsec = 0;
  85}
  86
  87static clock_access_fn __read_persistent_clock = dummy_clock_access;
  88static clock_access_fn __read_boot_clock = dummy_clock_access;;
  89
  90void read_persistent_clock(struct timespec *ts)
  91{
  92        __read_persistent_clock(ts);
  93}
  94
  95void read_boot_clock(struct timespec *ts)
  96{
  97        __read_boot_clock(ts);
  98}
  99
 100int __init register_persistent_clock(clock_access_fn read_boot,
 101                                     clock_access_fn read_persistent)
 102{
 103        /* Only allow the clockaccess functions to be registered once */
 104        if (__read_persistent_clock == dummy_clock_access &&
 105            __read_boot_clock == dummy_clock_access) {
 106                if (read_boot)
 107                        __read_boot_clock = read_boot;
 108                if (read_persistent)
 109                        __read_persistent_clock = read_persistent;
 110
 111                return 0;
 112        }
 113
 114        return -EINVAL;
 115}
 116
 117void __init time_init(void)
 118{
 119        if (machine_desc->init_time)
 120                machine_desc->init_time();
 121        else
 122                clocksource_of_init();
 123
 124        sched_clock_postinit();
 125}
 126