1/*
2 * Copyright (C) 2004-2007 Atmel Corporation
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8#include <linux/clk.h>
9#include <linux/clockchips.h>
10#include <linux/init.h>
11#include <linux/interrupt.h>
12#include <linux/irq.h>
13#include <linux/kernel.h>
14#include <linux/time.h>
15#include <linux/cpu.h>
16
17#include <asm/sysreg.h>
18
19#include <mach/pm.h>
20
21
22static cycle_t read_cycle_count(struct clocksource *cs)
23{
24	return (cycle_t)sysreg_read(COUNT);
25}
26
27/*
28 * The architectural cycle count registers are a fine clocksource unless
29 * the system idle loop use sleep states like "idle":  the CPU cycles
30 * measured by COUNT (and COMPARE) don't happen during sleep states.
31 * Their duration also changes if cpufreq changes the CPU clock rate.
32 * So we rate the clocksource using COUNT as very low quality.
33 */
34static struct clocksource counter = {
35	.name		= "avr32_counter",
36	.rating		= 50,
37	.read		= read_cycle_count,
38	.mask		= CLOCKSOURCE_MASK(32),
39	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
40};
41
42static irqreturn_t timer_interrupt(int irq, void *dev_id)
43{
44	struct clock_event_device *evdev = dev_id;
45
46	if (unlikely(!(intc_get_pending(0) & 1)))
47		return IRQ_NONE;
48
49	/*
50	 * Disable the interrupt until the clockevent subsystem
51	 * reprograms it.
52	 */
53	sysreg_write(COMPARE, 0);
54
55	evdev->event_handler(evdev);
56	return IRQ_HANDLED;
57}
58
59static struct irqaction timer_irqaction = {
60	.handler	= timer_interrupt,
61	/* Oprofile uses the same irq as the timer, so allow it to be shared */
62	.flags		= IRQF_TIMER | IRQF_SHARED,
63	.name		= "avr32_comparator",
64};
65
66static int comparator_next_event(unsigned long delta,
67		struct clock_event_device *evdev)
68{
69	unsigned long	flags;
70
71	raw_local_irq_save(flags);
72
73	/* The time to read COUNT then update COMPARE must be less
74	 * than the min_delta_ns value for this clockevent source.
75	 */
76	sysreg_write(COMPARE, (sysreg_read(COUNT) + delta) ? : 1);
77
78	raw_local_irq_restore(flags);
79
80	return 0;
81}
82
83static void comparator_mode(enum clock_event_mode mode,
84		struct clock_event_device *evdev)
85{
86	switch (mode) {
87	case CLOCK_EVT_MODE_ONESHOT:
88		pr_debug("%s: start\n", evdev->name);
89		/* FALLTHROUGH */
90	case CLOCK_EVT_MODE_RESUME:
91		/*
92		 * If we're using the COUNT and COMPARE registers we
93		 * need to force idle poll.
94		 */
95		cpu_idle_poll_ctrl(true);
96		break;
97	case CLOCK_EVT_MODE_UNUSED:
98	case CLOCK_EVT_MODE_SHUTDOWN:
99		sysreg_write(COMPARE, 0);
100		pr_debug("%s: stop\n", evdev->name);
101		if (evdev->mode == CLOCK_EVT_MODE_ONESHOT ||
102		    evdev->mode == CLOCK_EVT_MODE_RESUME) {
103			/*
104			 * Only disable idle poll if we have forced that
105			 * in a previous call.
106			 */
107			cpu_idle_poll_ctrl(false);
108		}
109		break;
110	default:
111		BUG();
112	}
113}
114
115static struct clock_event_device comparator = {
116	.name		= "avr32_comparator",
117	.features	= CLOCK_EVT_FEAT_ONESHOT,
118	.shift		= 16,
119	.rating		= 50,
120	.set_next_event	= comparator_next_event,
121	.set_mode	= comparator_mode,
122};
123
124void read_persistent_clock(struct timespec *ts)
125{
126	ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
127	ts->tv_nsec = 0;
128}
129
130void __init time_init(void)
131{
132	unsigned long counter_hz;
133	int ret;
134
135	/* figure rate for counter */
136	counter_hz = clk_get_rate(boot_cpu_data.clk);
137	ret = clocksource_register_hz(&counter, counter_hz);
138	if (ret)
139		pr_debug("timer: could not register clocksource: %d\n", ret);
140
141	/* setup COMPARE clockevent */
142	comparator.mult = div_sc(counter_hz, NSEC_PER_SEC, comparator.shift);
143	comparator.max_delta_ns = clockevent_delta2ns((u32)~0, &comparator);
144	comparator.min_delta_ns = clockevent_delta2ns(50, &comparator) + 1;
145	comparator.cpumask = cpumask_of(0);
146
147	sysreg_write(COMPARE, 0);
148	timer_irqaction.dev_id = &comparator;
149
150	ret = setup_irq(0, &timer_irqaction);
151	if (ret)
152		pr_debug("timer: could not request IRQ 0: %d\n", ret);
153	else {
154		clockevents_register_device(&comparator);
155
156		pr_info("%s: irq 0, %lu.%03lu MHz\n", comparator.name,
157				((counter_hz + 500) / 1000) / 1000,
158				((counter_hz + 500) / 1000) % 1000);
159	}
160}
161