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/clk-provider.h>
  15 #include <linux/clocksource.h>
  16 #include <linux/errno.h>
  17 #include <linux/export.h>
  18 #include <linux/init.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/irq.h>
  21 #include <linux/kernel.h>
  22 #include <linux/profile.h>
  23 #include <linux/sched.h>
  24 #include <linux/sched_clock.h>
  25 #include <linux/smp.h>
  26 #include <linux/time.h>
  27 #include <linux/timex.h>
  28 #include <linux/timer.h>
  29
  30 #include <asm/mach/arch.h>
  31 #include <asm/mach/time.h>
  32 #include <asm/stacktrace.h>
  33 #include <asm/thread_info.h>
  34
  35 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \
  36     defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE)
  37 /* this needs a better home */
  38 DEFINE_SPINLOCK(rtc_lock);
  39 EXPORT_SYMBOL(rtc_lock);
  40 #endif  /* pc-style 'CMOS' RTC support */
  41
  42 /* change this if you have some constant time drift */
  43 #define USECS_PER_JIFFY (1000000/HZ)
  44
  45 #ifdef CONFIG_SMP
  46 unsigned long profile_pc(struct pt_regs *regs)
  47 {
  48         struct stackframe frame;
  49
  50         if (!in_lock_functions(regs->ARM_pc))
  51                 return regs->ARM_pc;
  52
  53         arm_get_current_stackframe(regs, &frame);
  54         do {
  55                 int ret = unwind_frame(&frame);
  56                 if (ret < 0)
  57                         return 0;
  58         } while (in_lock_functions(frame.pc));
  59
  60         return frame.pc;
  61 }
  62 EXPORT_SYMBOL(profile_pc);
  63 #endif
  64
  65 #ifndef CONFIG_GENERIC_CLOCKEVENTS
  66 /*
  67  * Kernel system timer support.
  68  */
  69 void timer_tick(void)
  70 {
  71         profile_tick(CPU_PROFILING);
  72         xtime_update(1);
  73 #ifndef CONFIG_SMP
  74         update_process_times(user_mode(get_irq_regs()));
  75 #endif
  76 }
  77 #endif
  78
  79 static void dummy_clock_access(struct timespec64 *ts)
  80 {
  81         ts->tv_sec = 0;
  82         ts->tv_nsec = 0;
  83 }
  84
  85 static clock_access_fn __read_persistent_clock = dummy_clock_access;
  86 static clock_access_fn __read_boot_clock = dummy_clock_access;
  87
  88 void read_persistent_clock64(struct timespec64 *ts)
  89 {
  90         __read_persistent_clock(ts);
  91 }
  92
  93 void read_boot_clock64(struct timespec64 *ts)
  94 {
  95         __read_boot_clock(ts);
  96 }
  97
  98 int __init register_persistent_clock(clock_access_fn read_boot,
  99                                      clock_access_fn read_persistent)
 100 {
 101         /* Only allow the clockaccess functions to be registered once */
 102         if (__read_persistent_clock == dummy_clock_access &&
 103             __read_boot_clock == dummy_clock_access) {
 104                 if (read_boot)
 105                         __read_boot_clock = read_boot;
 106                 if (read_persistent)
 107                         __read_persistent_clock = read_persistent;
 108
 109                 return 0;
 110         }
 111
 112         return -EINVAL;
 113 }
 114
 115 void __init time_init(void)
 116 {
 117         if (machine_desc->init_time) {
 118                 machine_desc->init_time();
 119         } else {
 120 #ifdef CONFIG_COMMON_CLK
 121                 of_clk_init(NULL);
 122 #endif
 123                 timer_probe();
 124         }
 125 }