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