1/*
2 *  linux/arch/arm/kernel/time.c
3 *
4 *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
5 *  Modifications for ARM (C) 1994-2001 Russell King
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 *  This file contains the ARM-specific time handling details:
12 *  reading the RTC at bootup, etc...
13 */
14#include <linux/clk-provider.h>
15#include <linux/clocksource.h>
16#include <linux/errno.h>
17#include <linux/export.h>
18#include <linux/init.h>
19#include <linux/interrupt.h>
20#include <linux/irq.h>
21#include <linux/kernel.h>
22#include <linux/profile.h>
23#include <linux/sched.h>
24#include <linux/sched_clock.h>
25#include <linux/smp.h>
26#include <linux/time.h>
27#include <linux/timex.h>
28#include <linux/timer.h>
29
30#include <asm/mach/arch.h>
31#include <asm/mach/time.h>
32#include <asm/stacktrace.h>
33#include <asm/thread_info.h>
34
35#if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \
36    defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE)
37/* this needs a better home */
38DEFINE_SPINLOCK(rtc_lock);
39EXPORT_SYMBOL(rtc_lock);
40#endif	/* pc-style 'CMOS' RTC support */
41
42/* change this if you have some constant time drift */
43#define USECS_PER_JIFFY	(1000000/HZ)
44
45#ifdef CONFIG_SMP
46unsigned long profile_pc(struct pt_regs *regs)
47{
48	struct stackframe frame;
49
50	if (!in_lock_functions(regs->ARM_pc))
51		return regs->ARM_pc;
52
53	arm_get_current_stackframe(regs, &frame);
54	do {
55		int ret = unwind_frame(&frame);
56		if (ret < 0)
57			return 0;
58	} while (in_lock_functions(frame.pc));
59
60	return frame.pc;
61}
62EXPORT_SYMBOL(profile_pc);
63#endif
64
65#ifndef CONFIG_GENERIC_CLOCKEVENTS
66/*
67 * Kernel system timer support.
68 */
69void timer_tick(void)
70{
71	profile_tick(CPU_PROFILING);
72	xtime_update(1);
73#ifndef CONFIG_SMP
74	update_process_times(user_mode(get_irq_regs()));
75#endif
76}
77#endif
78
79static void dummy_clock_access(struct timespec64 *ts)
80{
81	ts->tv_sec = 0;
82	ts->tv_nsec = 0;
83}
84
85static clock_access_fn __read_persistent_clock = dummy_clock_access;
86static clock_access_fn __read_boot_clock = dummy_clock_access;;
87
88void read_persistent_clock64(struct timespec64 *ts)
89{
90	__read_persistent_clock(ts);
91}
92
93void read_boot_clock64(struct timespec64 *ts)
94{
95	__read_boot_clock(ts);
96}
97
98int __init register_persistent_clock(clock_access_fn read_boot,
99				     clock_access_fn read_persistent)
100{
101	/* Only allow the clockaccess functions to be registered once */
102	if (__read_persistent_clock == dummy_clock_access &&
103	    __read_boot_clock == dummy_clock_access) {
104		if (read_boot)
105			__read_boot_clock = read_boot;
106		if (read_persistent)
107			__read_persistent_clock = read_persistent;
108
109		return 0;
110	}
111
112	return -EINVAL;
113}
114
115void __init time_init(void)
116{
117	if (machine_desc->init_time) {
118		machine_desc->init_time();
119	} else {
120#ifdef CONFIG_COMMON_CLK
121		of_clk_init(NULL);
122#endif
123		clocksource_of_init();
124	}
125}
126