1/*
2 * arch/xtensa/kernel/time.c
3 *
4 * Timer and clock support.
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License.  See the file "COPYING" in the main directory of this archive
8 * for more details.
9 *
10 * Copyright (C) 2005 Tensilica Inc.
11 *
12 * Chris Zankel <chris@zankel.net>
13 */
14
15#include <linux/errno.h>
16#include <linux/sched.h>
17#include <linux/time.h>
18#include <linux/clocksource.h>
19#include <linux/clockchips.h>
20#include <linux/interrupt.h>
21#include <linux/module.h>
22#include <linux/init.h>
23#include <linux/irq.h>
24#include <linux/profile.h>
25#include <linux/delay.h>
26#include <linux/irqdomain.h>
27#include <linux/sched_clock.h>
28
29#include <asm/timex.h>
30#include <asm/platform.h>
31
32unsigned long ccount_freq;		/* ccount Hz */
33EXPORT_SYMBOL(ccount_freq);
34
35static cycle_t ccount_read(struct clocksource *cs)
36{
37	return (cycle_t)get_ccount();
38}
39
40static u64 notrace ccount_sched_clock_read(void)
41{
42	return get_ccount();
43}
44
45static struct clocksource ccount_clocksource = {
46	.name = "ccount",
47	.rating = 200,
48	.read = ccount_read,
49	.mask = CLOCKSOURCE_MASK(32),
50	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
51};
52
53static int ccount_timer_set_next_event(unsigned long delta,
54		struct clock_event_device *dev);
55struct ccount_timer {
56	struct clock_event_device evt;
57	int irq_enabled;
58	char name[24];
59};
60static DEFINE_PER_CPU(struct ccount_timer, ccount_timer);
61
62static int ccount_timer_set_next_event(unsigned long delta,
63		struct clock_event_device *dev)
64{
65	unsigned long flags, next;
66	int ret = 0;
67
68	local_irq_save(flags);
69	next = get_ccount() + delta;
70	set_linux_timer(next);
71	if (next - get_ccount() > delta)
72		ret = -ETIME;
73	local_irq_restore(flags);
74
75	return ret;
76}
77
78/*
79 * There is no way to disable the timer interrupt at the device level,
80 * only at the intenable register itself. Since enable_irq/disable_irq
81 * calls are nested, we need to make sure that these calls are
82 * balanced.
83 */
84static int ccount_timer_shutdown(struct clock_event_device *evt)
85{
86	struct ccount_timer *timer =
87		container_of(evt, struct ccount_timer, evt);
88
89	if (timer->irq_enabled) {
90		disable_irq(evt->irq);
91		timer->irq_enabled = 0;
92	}
93	return 0;
94}
95
96static int ccount_timer_set_oneshot(struct clock_event_device *evt)
97{
98	struct ccount_timer *timer =
99		container_of(evt, struct ccount_timer, evt);
100
101	if (!timer->irq_enabled) {
102		enable_irq(evt->irq);
103		timer->irq_enabled = 1;
104	}
105	return 0;
106}
107
108static irqreturn_t timer_interrupt(int irq, void *dev_id);
109static struct irqaction timer_irqaction = {
110	.handler =	timer_interrupt,
111	.flags =	IRQF_TIMER,
112	.name =		"timer",
113};
114
115void local_timer_setup(unsigned cpu)
116{
117	struct ccount_timer *timer = &per_cpu(ccount_timer, cpu);
118	struct clock_event_device *clockevent = &timer->evt;
119
120	timer->irq_enabled = 1;
121	clockevent->name = timer->name;
122	snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu);
123	clockevent->features = CLOCK_EVT_FEAT_ONESHOT;
124	clockevent->rating = 300;
125	clockevent->set_next_event = ccount_timer_set_next_event;
126	clockevent->set_state_shutdown = ccount_timer_shutdown;
127	clockevent->set_state_oneshot = ccount_timer_set_oneshot;
128	clockevent->tick_resume = ccount_timer_set_oneshot;
129	clockevent->cpumask = cpumask_of(cpu);
130	clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
131	if (WARN(!clockevent->irq, "error: can't map timer irq"))
132		return;
133	clockevents_config_and_register(clockevent, ccount_freq,
134					0xf, 0xffffffff);
135}
136
137void __init time_init(void)
138{
139#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
140	printk("Calibrating CPU frequency ");
141	platform_calibrate_ccount();
142	printk("%d.%02d MHz\n", (int)ccount_freq/1000000,
143			(int)(ccount_freq/10000)%100);
144#else
145	ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL;
146#endif
147	clocksource_register_hz(&ccount_clocksource, ccount_freq);
148	local_timer_setup(0);
149	setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction);
150	sched_clock_register(ccount_sched_clock_read, 32, ccount_freq);
151	clocksource_probe();
152}
153
154/*
155 * The timer interrupt is called HZ times per second.
156 */
157
158irqreturn_t timer_interrupt(int irq, void *dev_id)
159{
160	struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt;
161
162	set_linux_timer(get_linux_timer());
163	evt->event_handler(evt);
164
165	/* Allow platform to do something useful (Wdog). */
166	platform_heartbeat();
167
168	return IRQ_HANDLED;
169}
170
171#ifndef CONFIG_GENERIC_CALIBRATE_DELAY
172void calibrate_delay(void)
173{
174	loops_per_jiffy = ccount_freq / HZ;
175	printk("Calibrating delay loop (skipped)... "
176	       "%lu.%02lu BogoMIPS preset\n",
177	       loops_per_jiffy/(1000000/HZ),
178	       (loops_per_jiffy/(10000/HZ)) % 100);
179}
180#endif
181