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/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         write_seqlock(&xtime_lock);
 111         do_timer(1);
 112         write_sequnlock(&xtime_lock);
 113 #ifndef CONFIG_SMP
 114         update_process_times(user_mode(get_irq_regs()));
 115 #endif
 116 }
 117 #endif
 118
 119 #if defined(CONFIG_PM) && !defined(CONFIG_GENERIC_CLOCKEVENTS)
 120 static int timer_suspend(struct sys_device *dev, pm_message_t state)
 121 {
 122         struct sys_timer *timer = container_of(dev, struct sys_timer, dev);
 123
 124         if (timer->suspend != NULL)
 125                 timer->suspend();
 126
 127         return 0;
 128 }
 129
 130 static int timer_resume(struct sys_device *dev)
 131 {
 132         struct sys_timer *timer = container_of(dev, struct sys_timer, dev);
 133
 134         if (timer->resume != NULL)
 135                 timer->resume();
 136
 137         return 0;
 138 }
 139 #else
 140 #define timer_suspend NULL
 141 #define timer_resume NULL
 142 #endif
 143
 144 static struct sysdev_class timer_sysclass = {
 145         .name           = "timer",
 146         .suspend        = timer_suspend,
 147         .resume         = timer_resume,
 148 };
 149
 150 static int __init timer_init_sysfs(void)
 151 {
 152         int ret = sysdev_class_register(&timer_sysclass);
 153         if (ret == 0) {
 154                 system_timer->dev.cls = &timer_sysclass;
 155                 ret = sysdev_register(&system_timer->dev);
 156         }
 157
 158         return ret;
 159 }
 160
 161 device_initcall(timer_init_sysfs);
 162
 163 void __init time_init(void)
 164 {
 165         system_timer = machine_desc->timer;
 166         system_timer->init();
 167 #ifdef CONFIG_HAVE_SCHED_CLOCK
 168         sched_clock_postinit();
 169 #endif
 170 }
 171