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authorBaruch Siach <baruch@tkos.co.il>2013-06-18 08:48:53 +0300
committerChris Zankel <chris@zankel.net>2013-07-08 01:11:38 -0700
commit925f5532e83bfe236b4f69ba4265c19663cfa9c7 (patch)
tree354c55c160b21e40dfdde8b25563debbe0f32dc5 /arch/xtensa/kernel/time.c
parent8102f47ab5fcffc50f3ff94ca9b9073c12c18cc7 (diff)
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>
Diffstat (limited to 'arch/xtensa/kernel/time.c')
-rw-r--r--arch/xtensa/kernel/time.c110
1 files changed, 78 insertions, 32 deletions
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
index a32bc2ea7982..ece4f9588625 100644
--- a/arch/xtensa/kernel/time.c
+++ b/arch/xtensa/kernel/time.c
@@ -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;
}