tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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/export.h>
15#include <linux/kernel.h>
16#include <linux/interrupt.h>
17#include <linux/time.h>
18#include <linux/init.h>
19#include <linux/sched.h>
20#include <linux/smp.h>
21#include <linux/timex.h>
22#include <linux/errno.h>
23#include <linux/profile.h>
24#include <linux/syscore_ops.h>
25#include <linux/timer.h>
26#include <linux/irq.h>
27
28#include <asm/thread_info.h>
29#include <asm/sched_clock.h>
30#include <asm/stacktrace.h>
31#include <asm/mach/arch.h>
32#include <asm/mach/time.h>
33
34/*
35 * Our system timer.
36 */
37static struct sys_timer *system_timer;
38
39#if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \
40 defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE)
41/* this needs a better home */
42DEFINE_SPINLOCK(rtc_lock);
43EXPORT_SYMBOL(rtc_lock);
44#endif /* pc-style 'CMOS' RTC support */
45
46/* change this if you have some constant time drift */
47#define USECS_PER_JIFFY (1000000/HZ)
48
49#ifdef CONFIG_SMP
50unsigned long profile_pc(struct pt_regs *regs)
51{
52 struct stackframe frame;
53
54 if (!in_lock_functions(regs->ARM_pc))
55 return regs->ARM_pc;
56
57 frame.fp = regs->ARM_fp;
58 frame.sp = regs->ARM_sp;
59 frame.lr = regs->ARM_lr;
60 frame.pc = regs->ARM_pc;
61 do {
62 int ret = unwind_frame(&frame);
63 if (ret < 0)
64 return 0;
65 } while (in_lock_functions(frame.pc));
66
67 return frame.pc;
68}
69EXPORT_SYMBOL(profile_pc);
70#endif
71
72#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
73u32 arch_gettimeoffset(void)
74{
75 if (system_timer->offset != NULL)
76 return system_timer->offset() * 1000;
77
78 return 0;
79}
80#endif /* CONFIG_ARCH_USES_GETTIMEOFFSET */
81
82#ifndef CONFIG_GENERIC_CLOCKEVENTS
83/*
84 * Kernel system timer support.
85 */
86void timer_tick(void)
87{
88 profile_tick(CPU_PROFILING);
89 xtime_update(1);
90#ifndef CONFIG_SMP
91 update_process_times(user_mode(get_irq_regs()));
92#endif
93}
94#endif
95
96static void dummy_clock_access(struct timespec *ts)
97{
98 ts->tv_sec = 0;
99 ts->tv_nsec = 0;
100}
101
102static clock_access_fn __read_persistent_clock = dummy_clock_access;
103static clock_access_fn __read_boot_clock = dummy_clock_access;;
104
105void read_persistent_clock(struct timespec *ts)
106{
107 __read_persistent_clock(ts);
108}
109
110void read_boot_clock(struct timespec *ts)
111{
112 __read_boot_clock(ts);
113}
114
115int __init register_persistent_clock(clock_access_fn read_boot,
116 clock_access_fn read_persistent)
117{
118 /* Only allow the clockaccess functions to be registered once */
119 if (__read_persistent_clock == dummy_clock_access &&
120 __read_boot_clock == dummy_clock_access) {
121 if (read_boot)
122 __read_boot_clock = read_boot;
123 if (read_persistent)
124 __read_persistent_clock = read_persistent;
125
126 return 0;
127 }
128
129 return -EINVAL;
130}
131
132#if defined(CONFIG_PM) && !defined(CONFIG_GENERIC_CLOCKEVENTS)
133static int timer_suspend(void)
134{
135 if (system_timer->suspend)
136 system_timer->suspend();
137
138 return 0;
139}
140
141static void timer_resume(void)
142{
143 if (system_timer->resume)
144 system_timer->resume();
145}
146#else
147#define timer_suspend NULL
148#define timer_resume NULL
149#endif
150
151static struct syscore_ops timer_syscore_ops = {
152 .suspend = timer_suspend,
153 .resume = timer_resume,
154};
155
156static int __init timer_init_syscore_ops(void)
157{
158 register_syscore_ops(&timer_syscore_ops);
159
160 return 0;
161}
162
163device_initcall(timer_init_syscore_ops);
164
165void __init time_init(void)
166{
167 system_timer = machine_desc->timer;
168 system_timer->init();
169 sched_clock_postinit();
170}
171