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/timer.h>
  25 #include <linux/clocksource.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 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \
  35     defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE)
  36 /* this needs a better home */
  37 DEFINE_SPINLOCK(rtc_lock);
  38 EXPORT_SYMBOL(rtc_lock);
  39 #endif  /* pc-style 'CMOS' RTC support */
  40
  41 /* change this if you have some constant time drift */
  42 #define USECS_PER_JIFFY (1000000/HZ)
  43
  44 #ifdef CONFIG_SMP
  45 unsigned long profile_pc(struct pt_regs *regs)
  46 {
  47         struct stackframe frame;
  48
  49         if (!in_lock_functions(regs->ARM_pc))
  50                 return regs->ARM_pc;
  51
  52         frame.fp = regs->ARM_fp;
  53         frame.sp = regs->ARM_sp;
  54         frame.lr = regs->ARM_lr;
  55         frame.pc = regs->ARM_pc;
  56         do {
  57                 int ret = unwind_frame(&frame);
  58                 if (ret < 0)
  59                         return 0;
  60         } while (in_lock_functions(frame.pc));
  61
  62         return frame.pc;
  63 }
  64 EXPORT_SYMBOL(profile_pc);
  65 #endif
  66
  67 #ifndef CONFIG_GENERIC_CLOCKEVENTS
  68 /*
  69  * Kernel system timer support.
  70  */
  71 void timer_tick(void)
  72 {
  73         profile_tick(CPU_PROFILING);
  74         xtime_update(1);
  75 #ifndef CONFIG_SMP
  76         update_process_times(user_mode(get_irq_regs()));
  77 #endif
  78 }
  79 #endif
  80
  81 static void dummy_clock_access(struct timespec *ts)
  82 {
  83         ts->tv_sec = 0;
  84         ts->tv_nsec = 0;
  85 }
  86
  87 static clock_access_fn __read_persistent_clock = dummy_clock_access;
  88 static clock_access_fn __read_boot_clock = dummy_clock_access;;
  89
  90 void read_persistent_clock(struct timespec *ts)
  91 {
  92         __read_persistent_clock(ts);
  93 }
  94
  95 void read_boot_clock(struct timespec *ts)
  96 {
  97         __read_boot_clock(ts);
  98 }
  99
 100 int __init register_persistent_clock(clock_access_fn read_boot,
 101                                      clock_access_fn read_persistent)
 102 {
 103         /* Only allow the clockaccess functions to be registered once */
 104         if (__read_persistent_clock == dummy_clock_access &&
 105             __read_boot_clock == dummy_clock_access) {
 106                 if (read_boot)
 107                         __read_boot_clock = read_boot;
 108                 if (read_persistent)
 109                         __read_persistent_clock = read_persistent;
 110
 111                 return 0;
 112         }
 113
 114         return -EINVAL;
 115 }
 116
 117 void __init time_init(void)
 118 {
 119         if (machine_desc->init_time)
 120                 machine_desc->init_time();
 121         else
 122                 clocksource_of_init();
 123
 124         sched_clock_postinit();
 125 }