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