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/clockchips.h>
  13 #include <linux/clocksource.h>
  14 #include <linux/errno.h>
  15 #include <linux/export.h>
  16 #include <linux/init.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/irq.h>
  19 #include <linux/kernel.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 */
  36 DEFINE_SPINLOCK(rtc_lock);
  37 EXPORT_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
  44 unsigned 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 }
  60 EXPORT_SYMBOL(profile_pc);
  61 #endif
  62
  63 #ifndef CONFIG_GENERIC_CLOCKEVENTS
  64 /*
  65  * Kernel system timer support.
  66  */
  67 void 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
  77 static void dummy_clock_access(struct timespec64 *ts)
  78 {
  79         ts->tv_sec = 0;
  80         ts->tv_nsec = 0;
  81 }
  82
  83 static clock_access_fn __read_persistent_clock = dummy_clock_access;
  84
  85 void read_persistent_clock64(struct timespec64 *ts)
  86 {
  87         __read_persistent_clock(ts);
  88 }
  89
  90 int __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
 102 void __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 }