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