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/arch.h>
  34 #include <asm/mach/time.h>
  35
  36 /*
  37  * Our system timer.
  38  */
  39 static struct sys_timer *system_timer;
  40
  41 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE)
  42 /* this needs a better home */
  43 DEFINE_SPINLOCK(rtc_lock);
  44
  45 #ifdef CONFIG_RTC_DRV_CMOS_MODULE
  46 EXPORT_SYMBOL(rtc_lock);
  47 #endif
  48 #endif  /* pc-style 'CMOS' RTC support */
  49
  50 /* change this if you have some constant time drift */
  51 #define USECS_PER_JIFFY (1000000/HZ)
  52
  53 #ifdef CONFIG_SMP
  54 unsigned long profile_pc(struct pt_regs *regs)
  55 {
  56         struct stackframe frame;
  57
  58         if (!in_lock_functions(regs->ARM_pc))
  59                 return regs->ARM_pc;
  60
  61         frame.fp = regs->ARM_fp;
  62         frame.sp = regs->ARM_sp;
  63         frame.lr = regs->ARM_lr;
  64         frame.pc = regs->ARM_pc;
  65         do {
  66                 int ret = unwind_frame(&frame);
  67                 if (ret < 0)
  68                         return 0;
  69         } while (in_lock_functions(frame.pc));
  70
  71         return frame.pc;
  72 }
  73 EXPORT_SYMBOL(profile_pc);
  74 #endif
  75
  76 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
  77 u32 arch_gettimeoffset(void)
  78 {
  79         if (system_timer->offset != NULL)
  80                 return system_timer->offset() * 1000;
  81
  82         return 0;
  83 }
  84 #endif /* CONFIG_ARCH_USES_GETTIMEOFFSET */
  85
  86 #ifdef CONFIG_LEDS_TIMER
  87 static inline void do_leds(void)
  88 {
  89         static unsigned int count = HZ/2;
  90
  91         if (--count == 0) {
  92                 count = HZ/2;
  93                 leds_event(led_timer);
  94         }
  95 }
  96 #else
  97 #define do_leds()
  98 #endif
  99
 100
 101 #ifndef CONFIG_GENERIC_CLOCKEVENTS
 102 /*
 103  * Kernel system timer support.
 104  */
 105 void timer_tick(void)
 106 {
 107         profile_tick(CPU_PROFILING);
 108         do_leds();
 109         write_seqlock(&xtime_lock);
 110         do_timer(1);
 111         write_sequnlock(&xtime_lock);
 112 #ifndef CONFIG_SMP
 113         update_process_times(user_mode(get_irq_regs()));
 114 #endif
 115 }
 116 #endif
 117
 118 #if defined(CONFIG_PM) && !defined(CONFIG_GENERIC_CLOCKEVENTS)
 119 static int timer_suspend(struct sys_device *dev, pm_message_t state)
 120 {
 121         struct sys_timer *timer = container_of(dev, struct sys_timer, dev);
 122
 123         if (timer->suspend != NULL)
 124                 timer->suspend();
 125
 126         return 0;
 127 }
 128
 129 static int timer_resume(struct sys_device *dev)
 130 {
 131         struct sys_timer *timer = container_of(dev, struct sys_timer, dev);
 132
 133         if (timer->resume != NULL)
 134                 timer->resume();
 135
 136         return 0;
 137 }
 138 #else
 139 #define timer_suspend NULL
 140 #define timer_resume NULL
 141 #endif
 142
 143 static struct sysdev_class timer_sysclass = {
 144         .name           = "timer",
 145         .suspend        = timer_suspend,
 146         .resume         = timer_resume,
 147 };
 148
 149 static int __init timer_init_sysfs(void)
 150 {
 151         int ret = sysdev_class_register(&timer_sysclass);
 152         if (ret == 0) {
 153                 system_timer->dev.cls = &timer_sysclass;
 154                 ret = sysdev_register(&system_timer->dev);
 155         }
 156
 157         return ret;
 158 }
 159
 160 device_initcall(timer_init_sysfs);
 161
 162 void __init time_init(void)
 163 {
 164         system_timer = machine_desc->timer;
 165         system_timer->init();
 166 }
 167