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