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/*
* Copyright (C) 2004-2007 Atmel Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/cpu.h>
#include <asm/sysreg.h>
#include <mach/pm.h>
static bool disable_cpu_idle_poll;
static u64 read_cycle_count(struct clocksource *cs)
{
return (u64)sysreg_read(COUNT);
}
/*
* The architectural cycle count registers are a fine clocksource unless
* the system idle loop use sleep states like "idle": the CPU cycles
* measured by COUNT (and COMPARE) don't happen during sleep states.
* Their duration also changes if cpufreq changes the CPU clock rate.
* So we rate the clocksource using COUNT as very low quality.
*/
static struct clocksource counter = {
.name = "avr32_counter",
.rating = 50,
.read = read_cycle_count,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static irqreturn_t timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evdev = dev_id;
if (unlikely(!(intc_get_pending(0) & 1)))
return IRQ_NONE;
/*
* Disable the interrupt until the clockevent subsystem
* reprograms it.
*/
sysreg_write(COMPARE, 0);
evdev->event_handler(evdev);
return IRQ_HANDLED;
}
static struct irqaction timer_irqaction = {
.handler = timer_interrupt,
/* Oprofile uses the same irq as the timer, so allow it to be shared */
.flags = IRQF_TIMER | IRQF_SHARED,
.name = "avr32_comparator",
};
static int comparator_next_event(unsigned long delta,
struct clock_event_device *evdev)
{
unsigned long flags;
raw_local_irq_save(flags);
/* The time to read COUNT then update COMPARE must be less
* than the min_delta_ns value for this clockevent source.
*/
sysreg_write(COMPARE, (sysreg_read(COUNT) + delta) ? : 1);
raw_local_irq_restore(flags);
return 0;
}
static int comparator_shutdown(struct clock_event_device *evdev)
{
pr_debug("%s: %s\n", __func__, evdev->name);
sysreg_write(COMPARE, 0);
if (disable_cpu_idle_poll) {
disable_cpu_idle_poll = false;
/*
* Only disable idle poll if we have forced that
* in a previous call.
*/
cpu_idle_poll_ctrl(false);
}
return 0;
}
static int comparator_set_oneshot(struct clock_event_device *evdev)
{
pr_debug("%s: %s\n", __func__, evdev->name);
disable_cpu_idle_poll = true;
/*
* If we're using the COUNT and COMPARE registers we
* need to force idle poll.
*/
cpu_idle_poll_ctrl(true);
return 0;
}
static struct clock_event_device comparator = {
.name = "avr32_comparator",
.features = CLOCK_EVT_FEAT_ONESHOT,
.shift = 16,
.rating = 50,
.set_next_event = comparator_next_event,
.set_state_shutdown = comparator_shutdown,
.set_state_oneshot = comparator_set_oneshot,
.tick_resume = comparator_set_oneshot,
};
void read_persistent_clock(struct timespec *ts)
{
ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
ts->tv_nsec = 0;
}
void __init time_init(void)
{
unsigned long counter_hz;
int ret;
/* figure rate for counter */
counter_hz = clk_get_rate(boot_cpu_data.clk);
ret = clocksource_register_hz(&counter, counter_hz);
if (ret)
pr_debug("timer: could not register clocksource: %d\n", ret);
/* setup COMPARE clockevent */
comparator.mult = div_sc(counter_hz, NSEC_PER_SEC, comparator.shift);
comparator.max_delta_ns = clockevent_delta2ns((u32)~0, &comparator);
comparator.min_delta_ns = clockevent_delta2ns(50, &comparator) + 1;
comparator.cpumask = cpumask_of(0);
sysreg_write(COMPARE, 0);
timer_irqaction.dev_id = &comparator;
ret = setup_irq(0, &timer_irqaction);
if (ret)
pr_debug("timer: could not request IRQ 0: %d\n", ret);
else {
clockevents_register_device(&comparator);
pr_info("%s: irq 0, %lu.%03lu MHz\n", comparator.name,
((counter_hz + 500) / 1000) / 1000,
((counter_hz + 500) / 1000) % 1000);
}
}
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