1. 根目录:
2. arch
3. mips
4. kernel
5. cevt-gic.c

/*
 * 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) 2013  Imagination Technologies Ltd.
 */
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/irq.h>

#include <asm/time.h>
#include <asm/gic.h>
#include <asm/mips-boards/maltaint.h>

DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
int gic_timer_irq_installed;


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_compare(cnt);
	res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0;
	return res;
}

void gic_set_clock_mode(enum clock_event_mode mode,
				struct clock_event_device *evt)
{
	/* Nothing to do ...  */
}

irqreturn_t gic_compare_interrupt(int irq, void *dev_id)
{
	struct clock_event_device *cd;
	int cpu = smp_processor_id();

	gic_write_compare(gic_read_compare());
	cd = &per_cpu(gic_clockevent_device, cpu);
	cd->event_handler(cd);
	return IRQ_HANDLED;
}

struct irqaction gic_compare_irqaction = {
	.handler = gic_compare_interrupt,
	.flags = IRQF_PERCPU | IRQF_TIMER,
	.name = "timer",
};


void gic_event_handler(struct clock_event_device *dev)
{
}

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;

	cd = &per_cpu(gic_clockevent_device, cpu);

	cd->name		= "MIPS GIC";
	cd->features		= CLOCK_EVT_FEAT_ONESHOT;

	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;
	cd->event_handler	= gic_event_handler;

	clockevents_register_device(cd);

	GICWRITE(GIC_REG(VPE_LOCAL, GIC_VPE_COMPARE_MAP), 0x80000002);
	GICWRITE(GIC_REG(VPE_LOCAL, GIC_VPE_SMASK), GIC_VPE_SMASK_CMP_MSK);

	if (gic_timer_irq_installed)
		return 0;

	gic_timer_irq_installed = 1;

	setup_irq(irq, &gic_compare_irqaction);
	irq_set_handler(irq, handle_percpu_irq);
	return 0;
}