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xtensa: ccount based clockevent implementation 

Reused some code from a preliminary implementation by Max Fillippov.

Cc: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Chris Zankel <chris@zankel.net>
This commit is contained in:
Baruch Siach 2013-06-18 08:48:53 +03:00 committed by Chris Zankel
parent 8102f47ab5
commit 925f5532e8
2 changed files with 79 additions and 32 deletions
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1
arch/xtensa/Kconfig
View File

@ -6,6 +6,7 @@ config XTENSA
select ARCH_WANT_FRAME_POINTERS
select HAVE_IDE
select GENERIC_ATOMIC64
select GENERIC_CLOCKEVENTS
select HAVE_GENERIC_HARDIRQS
select VIRT_TO_BUS
select GENERIC_IRQ_SHOW

110
arch/xtensa/kernel/time.c
View File

@ -16,6 +16,7 @@
#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>
@ -43,16 +44,80 @@ static struct clocksource ccount_clocksource = {
.mask = CLOCKSOURCE_MASK(32),
};
static int ccount_timer_set_next_event(unsigned long delta,
struct clock_event_device *dev);
static void ccount_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt);
static struct ccount_timer_t {
struct clock_event_device evt;
int irq_enabled;
} ccount_timer = {
.evt = {
.name = "ccount_clockevent",
.features = CLOCK_EVT_FEAT_ONESHOT,
.rating = 300,
.set_next_event = ccount_timer_set_next_event,
.set_mode = ccount_timer_set_mode,
},
};
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;
}
static void ccount_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
struct ccount_timer_t *timer =
container_of(evt, struct ccount_timer_t, evt);
/*
* 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.
*/
switch (mode) {
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
if (timer->irq_enabled) {
disable_irq(evt->irq);
timer->irq_enabled = 0;
}
break;
case CLOCK_EVT_MODE_RESUME:
case CLOCK_EVT_MODE_ONESHOT:
if (!timer->irq_enabled) {
enable_irq(evt->irq);
timer->irq_enabled = 1;
}
default:
break;
}
}
static irqreturn_t timer_interrupt(int irq, void *dev_id);
static struct irqaction timer_irqaction = {
.handler = timer_interrupt,
.flags = IRQF_DISABLED,
.flags = IRQF_TIMER,
.name = "timer",
.dev_id = &ccount_timer,
};
void __init time_init(void)
{
unsigned int irq;
#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
printk("Calibrating CPU frequency ");
platform_calibrate_ccount();
@ -61,11 +126,14 @@ void __init time_init(void)
#endif
clocksource_register_hz(&ccount_clocksource, CCOUNT_PER_JIFFY * HZ);
/* Initialize the linux timer interrupt. */
irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
setup_irq(irq, &timer_irqaction);
set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
ccount_timer.evt.cpumask = cpumask_of(0);
ccount_timer.evt.irq = irq_create_mapping(NULL, LINUX_TIMER_INT);
if (WARN(!ccount_timer.evt.irq, "error: can't map timer irq"))
return;
clockevents_config_and_register(&ccount_timer.evt, ccount_freq, 0xf,
0xffffffff);
setup_irq(ccount_timer.evt.irq, &timer_irqaction);
ccount_timer.irq_enabled = 1;
}
/*
@ -74,36 +142,14 @@ void __init time_init(void)
irqreturn_t timer_interrupt (int irq, void *dev_id)
{
struct ccount_timer_t *timer = dev_id;
struct clock_event_device *evt = &timer->evt;
unsigned long next;
next = get_linux_timer();
again:
while ((signed long)(get_ccount() - next) > 0) {
profile_tick(CPU_PROFILING);
#ifndef CONFIG_SMP
update_process_times(user_mode(get_irq_regs()));
#endif
xtime_update(1); /* Linux handler in kernel/time/timekeeping */
/* Note that writing CCOMPARE clears the interrupt. */
next += CCOUNT_PER_JIFFY;
set_linux_timer(next);
}
evt->event_handler(evt);
/* Allow platform to do something useful (Wdog). */
platform_heartbeat();
/* Make sure we didn't miss any tick... */
if ((signed long)(get_ccount() - next) > 0)
goto again;
return IRQ_HANDLED;
}