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 */
  35 DEFINE_SPINLOCK(rtc_lock);
  36 EXPORT_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
  43 unsigned 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 }
  59 EXPORT_SYMBOL(profile_pc);
  60 #endif
  61
  62 #ifndef CONFIG_GENERIC_CLOCKEVENTS
  63 /*
  64  * Kernel system timer support.
  65  */
  66 void 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
  76 static void dummy_clock_access(struct timespec64 *ts)
  77 {
  78         ts->tv_sec = 0;
  79         ts->tv_nsec = 0;
  80 }
  81
  82 static clock_access_fn __read_persistent_clock = dummy_clock_access;
  83
  84 void read_persistent_clock64(struct timespec64 *ts)
  85 {
  86         __read_persistent_clock(ts);
  87 }
  88
  89 int __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
 101 void __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 }