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/sysdev.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/stacktrace.h>
  33 #include <asm/mach/time.h>
  34
  35 /*
  36  * Our system timer.
  37  */
  38 struct sys_timer *system_timer;
  39
  40 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE)
  41 /* this needs a better home */
  42 DEFINE_SPINLOCK(rtc_lock);
  43
  44 #ifdef CONFIG_RTC_DRV_CMOS_MODULE
  45 EXPORT_SYMBOL(rtc_lock);
  46 #endif
  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         write_seqlock(&xtime_lock);
 109         do_timer(1);
 110         write_sequnlock(&xtime_lock);
 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(struct sys_device *dev, pm_message_t state)
 119 {
 120         struct sys_timer *timer = container_of(dev, struct sys_timer, dev);
 121
 122         if (timer->suspend != NULL)
 123                 timer->suspend();
 124
 125         return 0;
 126 }
 127
 128 static int timer_resume(struct sys_device *dev)
 129 {
 130         struct sys_timer *timer = container_of(dev, struct sys_timer, dev);
 131
 132         if (timer->resume != NULL)
 133                 timer->resume();
 134
 135         return 0;
 136 }
 137 #else
 138 #define timer_suspend NULL
 139 #define timer_resume NULL
 140 #endif
 141
 142 static struct sysdev_class timer_sysclass = {
 143         .name           = "timer",
 144         .suspend        = timer_suspend,
 145         .resume         = timer_resume,
 146 };
 147
 148 static int __init timer_init_sysfs(void)
 149 {
 150         int ret = sysdev_class_register(&timer_sysclass);
 151         if (ret == 0) {
 152                 system_timer->dev.cls = &timer_sysclass;
 153                 ret = sysdev_register(&system_timer->dev);
 154         }
 155
 156         return ret;
 157 }
 158
 159 device_initcall(timer_init_sysfs);
 160
 161 void __init time_init(void)
 162 {
 163         system_timer->init();
 164 }
 165