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