xref: /openbmc/linux/arch/um/kernel/time.c (revision 22246614)
1 /*
2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3  * Licensed under the GPL
4  */
5 
6 #include <linux/clockchips.h>
7 #include <linux/init.h>
8 #include <linux/interrupt.h>
9 #include <linux/jiffies.h>
10 #include <linux/threads.h>
11 #include <asm/irq.h>
12 #include <asm/param.h>
13 #include "kern_util.h"
14 #include "os.h"
15 
16 /*
17  * Scheduler clock - returns current time in nanosec units.
18  */
19 unsigned long long sched_clock(void)
20 {
21 	return (unsigned long long)jiffies_64 * (NSEC_PER_SEC / HZ);
22 }
23 
24 void timer_handler(int sig, struct uml_pt_regs *regs)
25 {
26 	unsigned long flags;
27 
28 	local_irq_save(flags);
29 	do_IRQ(TIMER_IRQ, regs);
30 	local_irq_restore(flags);
31 }
32 
33 static void itimer_set_mode(enum clock_event_mode mode,
34 			    struct clock_event_device *evt)
35 {
36 	switch (mode) {
37 	case CLOCK_EVT_MODE_PERIODIC:
38 		set_interval();
39 		break;
40 
41 	case CLOCK_EVT_MODE_SHUTDOWN:
42 	case CLOCK_EVT_MODE_UNUSED:
43 	case CLOCK_EVT_MODE_ONESHOT:
44 		disable_timer();
45 		break;
46 
47 	case CLOCK_EVT_MODE_RESUME:
48 		break;
49 	}
50 }
51 
52 static int itimer_next_event(unsigned long delta,
53 			     struct clock_event_device *evt)
54 {
55 	return timer_one_shot(delta + 1);
56 }
57 
58 static struct clock_event_device itimer_clockevent = {
59 	.name		= "itimer",
60 	.rating		= 250,
61 	.cpumask	= CPU_MASK_ALL,
62 	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
63 	.set_mode	= itimer_set_mode,
64 	.set_next_event = itimer_next_event,
65 	.shift		= 32,
66 	.irq		= 0,
67 };
68 
69 static irqreturn_t um_timer(int irq, void *dev)
70 {
71 	(*itimer_clockevent.event_handler)(&itimer_clockevent);
72 
73 	return IRQ_HANDLED;
74 }
75 
76 static cycle_t itimer_read(void)
77 {
78 	return os_nsecs() / 1000;
79 }
80 
81 static struct clocksource itimer_clocksource = {
82 	.name		= "itimer",
83 	.rating		= 300,
84 	.read		= itimer_read,
85 	.mask		= CLOCKSOURCE_MASK(64),
86 	.mult		= 1000,
87 	.shift		= 0,
88 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
89 };
90 
91 static void __init setup_itimer(void)
92 {
93 	int err;
94 
95 	err = request_irq(TIMER_IRQ, um_timer, IRQF_DISABLED, "timer", NULL);
96 	if (err != 0)
97 		printk(KERN_ERR "register_timer : request_irq failed - "
98 		       "errno = %d\n", -err);
99 
100 	itimer_clockevent.mult = div_sc(HZ, NSEC_PER_SEC, 32);
101 	itimer_clockevent.max_delta_ns =
102 		clockevent_delta2ns(60 * HZ, &itimer_clockevent);
103 	itimer_clockevent.min_delta_ns =
104 		clockevent_delta2ns(1, &itimer_clockevent);
105 	err = clocksource_register(&itimer_clocksource);
106 	if (err) {
107 		printk(KERN_ERR "clocksource_register returned %d\n", err);
108 		return;
109 	}
110 	clockevents_register_device(&itimer_clockevent);
111 }
112 
113 void __init time_init(void)
114 {
115 	long long nsecs;
116 
117 	timer_init();
118 
119 	nsecs = os_nsecs();
120 	set_normalized_timespec(&wall_to_monotonic, -nsecs / NSEC_PER_SEC,
121 				-nsecs % NSEC_PER_SEC);
122 	set_normalized_timespec(&xtime, nsecs / NSEC_PER_SEC,
123 				nsecs % NSEC_PER_SEC);
124 	late_time_init = setup_itimer;
125 }
126