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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/clk.h>
#include <linux/clockchips.h>
#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irqchip/mips-gic.h>
#include <linux/notifier.h>
#include <linux/of_irq.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/time.h>
static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
static int gic_timer_irq;
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",
};
static void gic_clockevent_cpu_init(struct clock_event_device *cd)
{
unsigned int cpu = smp_processor_id();
cd->name = "MIPS GIC";
cd->features = CLOCK_EVT_FEAT_ONESHOT |
CLOCK_EVT_FEAT_C3STOP;
cd->rating = 350;
cd->irq = gic_timer_irq;
cd->cpumask = cpumask_of(cpu);
cd->set_next_event = gic_next_event;
cd->set_mode = gic_set_clock_mode;
clockevents_config_and_register(cd, gic_frequency, 0x300, 0x7fffffff);
enable_percpu_irq(gic_timer_irq, IRQ_TYPE_NONE);
}
static void gic_clockevent_cpu_exit(struct clock_event_device *cd)
{
disable_percpu_irq(gic_timer_irq);
}
static int gic_cpu_notifier(struct notifier_block *nb, unsigned long action,
void *data)
{
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_STARTING:
gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device));
break;
case CPU_DYING:
gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device));
break;
}
return NOTIFY_OK;
}
static struct notifier_block gic_cpu_nb = {
.notifier_call = gic_cpu_notifier,
};
static int gic_clockevent_init(void)
{
int ret;
if (!cpu_has_counter || !gic_frequency)
return -ENXIO;
ret = setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction);
if (ret < 0)
return ret;
ret = register_cpu_notifier(&gic_cpu_nb);
if (ret < 0)
pr_warn("GIC: Unable to register CPU notifier\n");
gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device));
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,
};
static void __init __gic_clocksource_init(void)
{
int ret;
/* Set clocksource mask. */
gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width());
/* Calculate a somewhat reasonable rating value. */
gic_clocksource.rating = 200 + gic_frequency / 10000000;
ret = clocksource_register_hz(&gic_clocksource, gic_frequency);
if (ret < 0)
pr_warn("GIC: Unable to register clocksource\n");
gic_clockevent_init();
/* And finally start the counter */
gic_start_count();
}
void __init gic_clocksource_init(unsigned int frequency)
{
gic_frequency = frequency;
gic_timer_irq = MIPS_GIC_IRQ_BASE +
GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE);
__gic_clocksource_init();
}
static void __init gic_clocksource_of_init(struct device_node *node)
{
struct clk *clk;
if (WARN_ON(!gic_present || !node->parent ||
!of_device_is_compatible(node->parent, "mti,gic")))
return;
clk = of_clk_get(node, 0);
if (!IS_ERR(clk)) {
if (clk_prepare_enable(clk) < 0) {
pr_err("GIC failed to enable clock\n");
clk_put(clk);
return;
}
gic_frequency = clk_get_rate(clk);
} else if (of_property_read_u32(node, "clock-frequency",
&gic_frequency)) {
pr_err("GIC frequency not specified.\n");
return;
}
gic_timer_irq = irq_of_parse_and_map(node, 0);
if (!gic_timer_irq) {
pr_err("GIC timer IRQ not specified.\n");
return;
}
__gic_clocksource_init();
}
CLOCKSOURCE_OF_DECLARE(mips_gic_timer, "mti,gic-timer",
gic_clocksource_of_init);
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