1/*
2 * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
3 * Licensed under the GPL
4 */
5
6#include "linux/kernel.h"
7#include "linux/module.h"
8#include "linux/unistd.h"
9#include "linux/stddef.h"
10#include "linux/spinlock.h"
11#include "linux/time.h"
12#include "linux/sched.h"
13#include "linux/interrupt.h"
14#include "linux/init.h"
15#include "linux/delay.h"
16#include "linux/hrtimer.h"
17#include "asm/irq.h"
18#include "asm/param.h"
19#include "asm/current.h"
20#include "kern_util.h"
21#include "mode.h"
22#include "os.h"
23
24int hz(void)
25{
26	return(HZ);
27}
28
29/*
30 * Scheduler clock - returns current time in nanosec units.
31 */
32unsigned long long sched_clock(void)
33{
34	return (unsigned long long)jiffies_64 * (1000000000 / HZ);
35}
36
37#ifdef CONFIG_UML_REAL_TIME_CLOCK
38static unsigned long long prev_nsecs[NR_CPUS];
39static long long delta[NR_CPUS];		/* Deviation per interval */
40#endif
41
42void timer_irq(union uml_pt_regs *regs)
43{
44	unsigned long long ticks = 0;
45#ifdef CONFIG_UML_REAL_TIME_CLOCK
46	int c = cpu();
47	if(prev_nsecs[c]){
48		/* We've had 1 tick */
49		unsigned long long nsecs = os_nsecs();
50
51		delta[c] += nsecs - prev_nsecs[c];
52		prev_nsecs[c] = nsecs;
53
54		/* Protect against the host clock being set backwards */
55		if(delta[c] < 0)
56			delta[c] = 0;
57
58		ticks += (delta[c] * HZ) / BILLION;
59		delta[c] -= (ticks * BILLION) / HZ;
60	}
61	else prev_nsecs[c] = os_nsecs();
62#else
63	ticks = 1;
64#endif
65	while(ticks > 0){
66		do_IRQ(TIMER_IRQ, regs);
67		ticks--;
68	}
69}
70
71/* Protects local_offset */
72static DEFINE_SPINLOCK(timer_spinlock);
73static unsigned long long local_offset = 0;
74
75static inline unsigned long long get_time(void)
76{
77	unsigned long long nsecs;
78	unsigned long flags;
79
80	spin_lock_irqsave(&timer_spinlock, flags);
81	nsecs = os_nsecs();
82	nsecs += local_offset;
83	spin_unlock_irqrestore(&timer_spinlock, flags);
84
85	return nsecs;
86}
87
88irqreturn_t um_timer(int irq, void *dev)
89{
90	unsigned long long nsecs;
91	unsigned long flags;
92
93	write_seqlock_irqsave(&xtime_lock, flags);
94
95	do_timer(1);
96
97#ifdef CONFIG_UML_REAL_TIME_CLOCK
98	nsecs = get_time();
99#else
100	nsecs = (unsigned long long) xtime.tv_sec * BILLION + xtime.tv_nsec +
101		BILLION / HZ;
102#endif
103	xtime.tv_sec = nsecs / NSEC_PER_SEC;
104	xtime.tv_nsec = nsecs - xtime.tv_sec * NSEC_PER_SEC;
105
106	write_sequnlock_irqrestore(&xtime_lock, flags);
107
108	return IRQ_HANDLED;
109}
110
111static void register_timer(void)
112{
113	int err;
114
115	err = request_irq(TIMER_IRQ, um_timer, IRQF_DISABLED, "timer", NULL);
116	if(err != 0)
117		printk(KERN_ERR "register_timer : request_irq failed - "
118		       "errno = %d\n", -err);
119
120	err = set_interval(1);
121	if(err != 0)
122		printk(KERN_ERR "register_timer : set_interval failed - "
123		       "errno = %d\n", -err);
124}
125
126extern void (*late_time_init)(void);
127
128void time_init(void)
129{
130	long long nsecs;
131
132	nsecs = os_nsecs();
133	set_normalized_timespec(&wall_to_monotonic, -nsecs / BILLION,
134				-nsecs % BILLION);
135	set_normalized_timespec(&xtime, nsecs / BILLION, nsecs % BILLION);
136	late_time_init = register_timer;
137}
138
139void do_gettimeofday(struct timeval *tv)
140{
141#ifdef CONFIG_UML_REAL_TIME_CLOCK
142	unsigned long long nsecs = get_time();
143#else
144	unsigned long long nsecs = (unsigned long long) xtime.tv_sec * BILLION +
145		xtime.tv_nsec;
146#endif
147	tv->tv_sec = nsecs / NSEC_PER_SEC;
148	/* Careful about calculations here - this was originally done as
149	 * (nsecs - tv->tv_sec * NSEC_PER_SEC) / NSEC_PER_USEC
150	 * which gave bogus (> 1000000) values.  Dunno why, suspect gcc
151	 * (4.0.0) miscompiled it, or there's a subtle 64/32-bit conversion
152	 * problem that I missed.
153	 */
154	nsecs -= tv->tv_sec * NSEC_PER_SEC;
155	tv->tv_usec = (unsigned long) nsecs / NSEC_PER_USEC;
156}
157
158static inline void set_time(unsigned long long nsecs)
159{
160	unsigned long long now;
161	unsigned long flags;
162
163	spin_lock_irqsave(&timer_spinlock, flags);
164	now = os_nsecs();
165	local_offset = nsecs - now;
166	spin_unlock_irqrestore(&timer_spinlock, flags);
167
168	clock_was_set();
169}
170
171int do_settimeofday(struct timespec *tv)
172{
173	set_time((unsigned long long) tv->tv_sec * NSEC_PER_SEC + tv->tv_nsec);
174
175	return 0;
176}
177
178void timer_handler(int sig, union uml_pt_regs *regs)
179{
180	if(current_thread->cpu == 0)
181		timer_irq(regs);
182	local_irq_disable();
183	irq_enter();
184	update_process_times(CHOOSE_MODE(
185	                     (UPT_SC(regs) && user_context(UPT_SP(regs))),
186			     (regs)->skas.is_user));
187	irq_exit();
188	local_irq_enable();
189}
190