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
profile_pc(struct pt_regs * regs)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  */
timer_tick(void)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 
dummy_clock_access(struct timespec64 * ts)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 
read_persistent_clock64(struct timespec64 * ts)84 void read_persistent_clock64(struct timespec64 *ts)
85 {
86 	__read_persistent_clock(ts);
87 }
88 
register_persistent_clock(clock_access_fn read_persistent)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 
time_init(void)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 }
112