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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
*/
#include <linux/clockchips.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irqchip/mips-gic.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/time.h>
#include <asm/time.h>
static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
static int gic_timer_irq_installed;
static unsigned int gic_frequency;
static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
{
u64 cnt;
int res;
cnt = gic_read_count();
cnt += (u64)delta;
gic_write_cpu_compare(cnt, cpumask_first(evt->cpumask));
res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0;
return res;
}
static void gic_set_clock_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
/* Nothing to do ... */
}
static irqreturn_t gic_compare_interrupt(int irq, void *dev_id)
{
struct clock_event_device *cd = dev_id;
gic_write_compare(gic_read_compare());
cd->event_handler(cd);
return IRQ_HANDLED;
}
struct irqaction gic_compare_irqaction = {
.handler = gic_compare_interrupt,
.percpu_dev_id = &gic_clockevent_device,
.flags = IRQF_PERCPU | IRQF_TIMER,
.name = "timer",
};
int gic_clockevent_init(void)
{
unsigned int cpu = smp_processor_id();
struct clock_event_device *cd;
unsigned int irq;
if (!cpu_has_counter || !gic_frequency)
return -ENXIO;
irq = MIPS_GIC_IRQ_BASE + GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE);
cd = &per_cpu(gic_clockevent_device, cpu);
cd->name = "MIPS GIC";
cd->features = CLOCK_EVT_FEAT_ONESHOT |
CLOCK_EVT_FEAT_C3STOP;
clockevent_set_clock(cd, gic_frequency);
/* Calculate the min / max delta */
cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);
cd->min_delta_ns = clockevent_delta2ns(0x300, cd);
cd->rating = 300;
cd->irq = irq;
cd->cpumask = cpumask_of(cpu);
cd->set_next_event = gic_next_event;
cd->set_mode = gic_set_clock_mode;
clockevents_register_device(cd);
if (!gic_timer_irq_installed) {
setup_percpu_irq(irq, &gic_compare_irqaction);
gic_timer_irq_installed = 1;
}
enable_percpu_irq(irq, IRQ_TYPE_NONE);
return 0;
}
static cycle_t gic_hpt_read(struct clocksource *cs)
{
return gic_read_count();
}
static struct clocksource gic_clocksource = {
.name = "GIC",
.read = gic_hpt_read,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
void __init gic_clocksource_init(unsigned int frequency)
{
gic_frequency = frequency;
/* Set clocksource mask. */
gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width());
/* Calculate a somewhat reasonable rating value. */
gic_clocksource.rating = 200 + frequency / 10000000;
clocksource_register_hz(&gic_clocksource, frequency);
}
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