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 */
  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 static void dummy_clock_access(struct timespec64 *ts)
  64 {
  65         ts->tv_sec = 0;
  66         ts->tv_nsec = 0;
  67 }
  68
  69 static clock_access_fn __read_persistent_clock = dummy_clock_access;
  70
  71 void read_persistent_clock64(struct timespec64 *ts)
  72 {
  73         __read_persistent_clock(ts);
  74 }
  75
  76 int __init register_persistent_clock(clock_access_fn read_persistent)
  77 {
  78         /* Only allow the clockaccess functions to be registered once */
  79         if (__read_persistent_clock == dummy_clock_access) {
  80                 if (read_persistent)
  81                         __read_persistent_clock = read_persistent;
  82                 return 0;
  83         }
  84
  85         return -EINVAL;
  86 }
  87
  88 void __init time_init(void)
  89 {
  90         if (machine_desc->init_time) {
  91                 machine_desc->init_time();
  92         } else {
  93 #ifdef CONFIG_COMMON_CLK
  94                 of_clk_init(NULL);
  95 #endif
  96                 timer_probe();
  97                 tick_setup_hrtimer_broadcast();
  98         }
  99 }