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/*
* arch/xtensa/kernel/time.c
*
* Timer and clock support.
*
* 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) 2005 Tensilica Inc.
*
* Chris Zankel <chris@zankel.net>
*/
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/profile.h>
#include <linux/delay.h>
#include <linux/irqdomain.h>
#include <linux/sched_clock.h>
#include <asm/timex.h>
#include <asm/platform.h>
unsigned long ccount_freq; /* ccount Hz */
EXPORT_SYMBOL(ccount_freq);
static u64 ccount_read(struct clocksource *cs)
{
return (u64)get_ccount();
}
static u64 notrace ccount_sched_clock_read(void)
{
return get_ccount();
}
static struct clocksource ccount_clocksource = {
.name = "ccount",
.rating = 200,
.read = ccount_read,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static int ccount_timer_set_next_event(unsigned long delta,
struct clock_event_device *dev);
struct ccount_timer {
struct clock_event_device evt;
int irq_enabled;
char name[24];
};
static DEFINE_PER_CPU(struct ccount_timer, ccount_timer);
static int ccount_timer_set_next_event(unsigned long delta,
struct clock_event_device *dev)
{
unsigned long flags, next;
int ret = 0;
local_irq_save(flags);
next = get_ccount() + delta;
set_linux_timer(next);
if (next - get_ccount() > delta)
ret = -ETIME;
local_irq_restore(flags);
return ret;
}
/*
* There is no way to disable the timer interrupt at the device level,
* only at the intenable register itself. Since enable_irq/disable_irq
* calls are nested, we need to make sure that these calls are
* balanced.
*/
static int ccount_timer_shutdown(struct clock_event_device *evt)
{
struct ccount_timer *timer =
container_of(evt, struct ccount_timer, evt);
if (timer->irq_enabled) {
disable_irq(evt->irq);
timer->irq_enabled = 0;
}
return 0;
}
static int ccount_timer_set_oneshot(struct clock_event_device *evt)
{
struct ccount_timer *timer =
container_of(evt, struct ccount_timer, evt);
if (!timer->irq_enabled) {
enable_irq(evt->irq);
timer->irq_enabled = 1;
}
return 0;
}
static irqreturn_t timer_interrupt(int irq, void *dev_id);
static struct irqaction timer_irqaction = {
.handler = timer_interrupt,
.flags = IRQF_TIMER,
.name = "timer",
};
void local_timer_setup(unsigned cpu)
{
struct ccount_timer *timer = &per_cpu(ccount_timer, cpu);
struct clock_event_device *clockevent = &timer->evt;
timer->irq_enabled = 1;
clockevent->name = timer->name;
snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu);
clockevent->features = CLOCK_EVT_FEAT_ONESHOT;
clockevent->rating = 300;
clockevent->set_next_event = ccount_timer_set_next_event;
clockevent->set_state_shutdown = ccount_timer_shutdown;
clockevent->set_state_oneshot = ccount_timer_set_oneshot;
clockevent->tick_resume = ccount_timer_set_oneshot;
clockevent->cpumask = cpumask_of(cpu);
clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
if (WARN(!clockevent->irq, "error: can't map timer irq"))
return;
clockevents_config_and_register(clockevent, ccount_freq,
0xf, 0xffffffff);
}
#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
#ifdef CONFIG_OF
static void __init calibrate_ccount(void)
{
struct device_node *cpu;
struct clk *clk;
cpu = of_find_compatible_node(NULL, NULL, "cdns,xtensa-cpu");
if (cpu) {
clk = of_clk_get(cpu, 0);
if (!IS_ERR(clk)) {
ccount_freq = clk_get_rate(clk);
return;
} else {
pr_warn("%s: CPU input clock not found\n",
__func__);
}
} else {
pr_warn("%s: CPU node not found in the device tree\n",
__func__);
}
platform_calibrate_ccount();
}
#else
static inline void calibrate_ccount(void)
{
platform_calibrate_ccount();
}
#endif
#endif
void __init time_init(void)
{
of_clk_init(NULL);
#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
pr_info("Calibrating CPU frequency ");
calibrate_ccount();
pr_cont("%d.%02d MHz\n",
(int)ccount_freq / 1000000,
(int)(ccount_freq / 10000) % 100);
#else
ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL;
#endif
WARN(!ccount_freq,
"%s: CPU clock frequency is not set up correctly\n",
__func__);
clocksource_register_hz(&ccount_clocksource, ccount_freq);
local_timer_setup(0);
setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction);
sched_clock_register(ccount_sched_clock_read, 32, ccount_freq);
clocksource_probe();
}
/*
* The timer interrupt is called HZ times per second.
*/
irqreturn_t timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt;
set_linux_timer(get_linux_timer());
evt->event_handler(evt);
/* Allow platform to do something useful (Wdog). */
platform_heartbeat();
return IRQ_HANDLED;
}
#ifndef CONFIG_GENERIC_CALIBRATE_DELAY
void calibrate_delay(void)
{
loops_per_jiffy = ccount_freq / HZ;
pr_info("Calibrating delay loop (skipped)... %lu.%02lu BogoMIPS preset\n",
loops_per_jiffy / (1000000 / HZ),
(loops_per_jiffy / (10000 / HZ)) % 100);
}
#endif
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