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/module.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/syscore_ops.h>
  25 #include <linux/timer.h>
  26 #include <linux/irq.h>
  27
  28 #include <linux/mc146818rtc.h>
  29
  30 #include <asm/leds.h>
  31 #include <asm/thread_info.h>
  32 #include <asm/sched_clock.h>
  33 #include <asm/stacktrace.h>
  34 #include <asm/mach/arch.h>
  35 #include <asm/mach/time.h>
  36
  37 /*
  38  * Our system timer.
  39  */
  40 static struct sys_timer *system_timer;
  41
  42 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE)
  43 /* this needs a better home */
  44 DEFINE_SPINLOCK(rtc_lock);
  45
  46 #ifdef CONFIG_RTC_DRV_CMOS_MODULE
  47 EXPORT_SYMBOL(rtc_lock);
  48 #endif
  49 #endif  /* pc-style 'CMOS' RTC support */
  50
  51 /* change this if you have some constant time drift */
  52 #define USECS_PER_JIFFY (1000000/HZ)
  53
  54 #ifdef CONFIG_SMP
  55 unsigned long profile_pc(struct pt_regs *regs)
  56 {
  57         struct stackframe frame;
  58
  59         if (!in_lock_functions(regs->ARM_pc))
  60                 return regs->ARM_pc;
  61
  62         frame.fp = regs->ARM_fp;
  63         frame.sp = regs->ARM_sp;
  64         frame.lr = regs->ARM_lr;
  65         frame.pc = regs->ARM_pc;
  66         do {
  67                 int ret = unwind_frame(&frame);
  68                 if (ret < 0)
  69                         return 0;
  70         } while (in_lock_functions(frame.pc));
  71
  72         return frame.pc;
  73 }
  74 EXPORT_SYMBOL(profile_pc);
  75 #endif
  76
  77 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
  78 u32 arch_gettimeoffset(void)
  79 {
  80         if (system_timer->offset != NULL)
  81                 return system_timer->offset() * 1000;
  82
  83         return 0;
  84 }
  85 #endif /* CONFIG_ARCH_USES_GETTIMEOFFSET */
  86
  87 #ifdef CONFIG_LEDS_TIMER
  88 static inline void do_leds(void)
  89 {
  90         static unsigned int count = HZ/2;
  91
  92         if (--count == 0) {
  93                 count = HZ/2;
  94                 leds_event(led_timer);
  95         }
  96 }
  97 #else
  98 #define do_leds()
  99 #endif
 100
 101
 102 #ifndef CONFIG_GENERIC_CLOCKEVENTS
 103 /*
 104  * Kernel system timer support.
 105  */
 106 void timer_tick(void)
 107 {
 108         profile_tick(CPU_PROFILING);
 109         do_leds();
 110         xtime_update(1);
 111 #ifndef CONFIG_SMP
 112         update_process_times(user_mode(get_irq_regs()));
 113 #endif
 114 }
 115 #endif
 116
 117 #if defined(CONFIG_PM) && !defined(CONFIG_GENERIC_CLOCKEVENTS)
 118 static int timer_suspend(void)
 119 {
 120         if (system_timer->suspend)
 121                 system_timer->suspend();
 122
 123         return 0;
 124 }
 125
 126 static void timer_resume(void)
 127 {
 128         if (system_timer->resume)
 129                 system_timer->resume();
 130 }
 131 #else
 132 #define timer_suspend NULL
 133 #define timer_resume NULL
 134 #endif
 135
 136 static struct syscore_ops timer_syscore_ops = {
 137         .suspend        = timer_suspend,
 138         .resume         = timer_resume,
 139 };
 140
 141 static int __init timer_init_syscore_ops(void)
 142 {
 143         register_syscore_ops(&timer_syscore_ops);
 144
 145         return 0;
 146 }
 147
 148 device_initcall(timer_init_syscore_ops);
 149
 150 void __init time_init(void)
 151 {
 152         system_timer = machine_desc->timer;
 153         system_timer->init();
 154 #ifdef CONFIG_HAVE_SCHED_CLOCK
 155         sched_clock_postinit();
 156 #endif
 157 }
 158