LXR linux/arch/arm/kernel/time.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  linux/arch/arm/kernel/time.c
   4 *
   5 *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   6 *  Modifications for ARM (C) 1994-2001 Russell King
   7 *
   8 *  This file contains the ARM-specific time handling details:
   9 *  reading the RTC at bootup, etc...
  10 */
  11#include <linux/clk-provider.h>
  12#include <linux/clocksource.h>
  13#include <linux/errno.h>
  14#include <linux/export.h>
  15#include <linux/init.h>
  16#include <linux/interrupt.h>
  17#include <linux/irq.h>
  18#include <linux/kernel.h>
  19#include <linux/profile.h>
  20#include <linux/sched.h>
  21#include <linux/sched_clock.h>
  22#include <linux/smp.h>
  23#include <linux/time.h>
  24#include <linux/timex.h>
  25#include <linux/timer.h>
  26
  27#include <asm/mach/arch.h>
  28#include <asm/mach/time.h>
  29#include <asm/stacktrace.h>
  30#include <asm/thread_info.h>
  31
  32#if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \
  33    defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE)
  34/* this needs a better home */
  35DEFINE_SPINLOCK(rtc_lock);
  36EXPORT_SYMBOL(rtc_lock);
  37#endif  /* pc-style 'CMOS' RTC support */
  38
  39/* change this if you have some constant time drift */
  40#define USECS_PER_JIFFY (1000000/HZ)
  41
  42#ifdef CONFIG_SMP
  43unsigned long profile_pc(struct pt_regs *regs)
  44{
  45        struct stackframe frame;
  46
  47        if (!in_lock_functions(regs->ARM_pc))
  48                return regs->ARM_pc;
  49
  50        arm_get_current_stackframe(regs, &frame);
  51        do {
  52                int ret = unwind_frame(&frame);
  53                if (ret < 0)
  54                        return 0;
  55        } while (in_lock_functions(frame.pc));
  56
  57        return frame.pc;
  58}
  59EXPORT_SYMBOL(profile_pc);
  60#endif
  61
  62#ifndef CONFIG_GENERIC_CLOCKEVENTS
  63/*
  64 * Kernel system timer support.
  65 */
  66void timer_tick(void)
  67{
  68        profile_tick(CPU_PROFILING);
  69        xtime_update(1);
  70#ifndef CONFIG_SMP
  71        update_process_times(user_mode(get_irq_regs()));
  72#endif
  73}
  74#endif
  75
  76static void dummy_clock_access(struct timespec64 *ts)
  77{
  78        ts->tv_sec = 0;
  79        ts->tv_nsec = 0;
  80}
  81
  82static clock_access_fn __read_persistent_clock = dummy_clock_access;
  83
  84void read_persistent_clock64(struct timespec64 *ts)
  85{
  86        __read_persistent_clock(ts);
  87}
  88
  89int __init register_persistent_clock(clock_access_fn read_persistent)
  90{
  91        /* Only allow the clockaccess functions to be registered once */
  92        if (__read_persistent_clock == dummy_clock_access) {
  93                if (read_persistent)
  94                        __read_persistent_clock = read_persistent;
  95                return 0;
  96        }
  97
  98        return -EINVAL;
  99}
 100
 101void __init time_init(void)
 102{
 103        if (machine_desc->init_time) {
 104                machine_desc->init_time();
 105        } else {
 106#ifdef CONFIG_COMMON_CLK
 107                of_clk_init(NULL);
 108#endif
 109                timer_probe();
 110        }
 111}
 112