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 <asm/leds.h>
  29 #include <asm/thread_info.h>
  30 #include <asm/sched_clock.h>
  31 #include <asm/stacktrace.h>
  32 #include <asm/mach/arch.h>
  33 #include <asm/mach/time.h>
  34
  35 /*
  36  * Our system timer.
  37  */
  38 static struct sys_timer *system_timer;
  39
  40 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \
  41     defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE)
  42 /* this needs a better home */
  43 DEFINE_SPINLOCK(rtc_lock);
  44 EXPORT_SYMBOL(rtc_lock);
  45 #endif  /* pc-style 'CMOS' RTC support */
  46
  47 /* change this if you have some constant time drift */
  48 #define USECS_PER_JIFFY (1000000/HZ)
  49
  50 #ifdef CONFIG_SMP
  51 unsigned long profile_pc(struct pt_regs *regs)
  52 {
  53         struct stackframe frame;
  54
  55         if (!in_lock_functions(regs->ARM_pc))
  56                 return regs->ARM_pc;
  57
  58         frame.fp = regs->ARM_fp;
  59         frame.sp = regs->ARM_sp;
  60         frame.lr = regs->ARM_lr;
  61         frame.pc = regs->ARM_pc;
  62         do {
  63                 int ret = unwind_frame(&frame);
  64                 if (ret < 0)
  65                         return 0;
  66         } while (in_lock_functions(frame.pc));
  67
  68         return frame.pc;
  69 }
  70 EXPORT_SYMBOL(profile_pc);
  71 #endif
  72
  73 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
  74 u32 arch_gettimeoffset(void)
  75 {
  76         if (system_timer->offset != NULL)
  77                 return system_timer->offset() * 1000;
  78
  79         return 0;
  80 }
  81 #endif /* CONFIG_ARCH_USES_GETTIMEOFFSET */
  82
  83 #ifdef CONFIG_LEDS_TIMER
  84 static inline void do_leds(void)
  85 {
  86         static unsigned int count = HZ/2;
  87
  88         if (--count == 0) {
  89                 count = HZ/2;
  90                 leds_event(led_timer);
  91         }
  92 }
  93 #else
  94 #define do_leds()
  95 #endif
  96
  97
  98 #ifndef CONFIG_GENERIC_CLOCKEVENTS
  99 /*
 100  * Kernel system timer support.
 101  */
 102 void timer_tick(void)
 103 {
 104         profile_tick(CPU_PROFILING);
 105         do_leds();
 106         xtime_update(1);
 107 #ifndef CONFIG_SMP
 108         update_process_times(user_mode(get_irq_regs()));
 109 #endif
 110 }
 111 #endif
 112
 113 static void dummy_clock_access(struct timespec *ts)
 114 {
 115         ts->tv_sec = 0;
 116         ts->tv_nsec = 0;
 117 }
 118
 119 static clock_access_fn __read_persistent_clock = dummy_clock_access;
 120 static clock_access_fn __read_boot_clock = dummy_clock_access;;
 121
 122 void read_persistent_clock(struct timespec *ts)
 123 {
 124         __read_persistent_clock(ts);
 125 }
 126
 127 void read_boot_clock(struct timespec *ts)
 128 {
 129         __read_boot_clock(ts);
 130 }
 131
 132 int __init register_persistent_clock(clock_access_fn read_boot,
 133                                      clock_access_fn read_persistent)
 134 {
 135         /* Only allow the clockaccess functions to be registered once */
 136         if (__read_persistent_clock == dummy_clock_access &&
 137             __read_boot_clock == dummy_clock_access) {
 138                 if (read_boot)
 139                         __read_boot_clock = read_boot;
 140                 if (read_persistent)
 141                         __read_persistent_clock = read_persistent;
 142
 143                 return 0;
 144         }
 145
 146         return -EINVAL;
 147 }
 148
 149 #if defined(CONFIG_PM) && !defined(CONFIG_GENERIC_CLOCKEVENTS)
 150 static int timer_suspend(void)
 151 {
 152         if (system_timer->suspend)
 153                 system_timer->suspend();
 154
 155         return 0;
 156 }
 157
 158 static void timer_resume(void)
 159 {
 160         if (system_timer->resume)
 161                 system_timer->resume();
 162 }
 163 #else
 164 #define timer_suspend NULL
 165 #define timer_resume NULL
 166 #endif
 167
 168 static struct syscore_ops timer_syscore_ops = {
 169         .suspend        = timer_suspend,
 170         .resume         = timer_resume,
 171 };
 172
 173 static int __init timer_init_syscore_ops(void)
 174 {
 175         register_syscore_ops(&timer_syscore_ops);
 176
 177         return 0;
 178 }
 179
 180 device_initcall(timer_init_syscore_ops);
 181
 182 void __init time_init(void)
 183 {
 184         system_timer = machine_desc->timer;
 185         system_timer->init();
 186         sched_clock_postinit();
 187 }
 188