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Subject[PATCH 3/4] clocksource: mips-gic-timer: Register as sched_clock
Date
From: Paul Burton <paulburton@kernel.org>

The MIPS GIC timer is well suited for use as sched_clock, so register it
as such.

Whilst the existing gic_read_count() function matches the prototype
needed by sched_clock_register() already, we split it into 2 functions
in order to remove the need to evaluate the mips_cm_is64 condition
within each call since sched_clock should be as fast as possible.

Signed-off-by: Paul Burton <paulburton@kernel.org>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
---
drivers/clocksource/mips-gic-timer.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/clocksource/mips-gic-timer.c b/drivers/clocksource/mips-gic-timer.c
index 37671a5d4ed9..8239ff99cfe4 100644
--- a/drivers/clocksource/mips-gic-timer.c
+++ b/drivers/clocksource/mips-gic-timer.c
@@ -16,6 +16,7 @@
#include <linux/notifier.h>
#include <linux/of_irq.h>
#include <linux/percpu.h>
+#include <linux/sched_clock.h>
#include <linux/smp.h>
#include <linux/time.h>
#include <asm/mips-cps.h>
@@ -24,13 +25,10 @@ static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
static int gic_timer_irq;
static unsigned int gic_frequency;

-static u64 notrace gic_read_count(void)
+static u64 notrace gic_read_count_2x32(void)
{
unsigned int hi, hi2, lo;

- if (mips_cm_is64)
- return read_gic_counter();
-
do {
hi = read_gic_counter_32h();
lo = read_gic_counter_32l();
@@ -40,6 +38,19 @@ static u64 notrace gic_read_count(void)
return (((u64) hi) << 32) + lo;
}

+static u64 notrace gic_read_count_64(void)
+{
+ return read_gic_counter();
+}
+
+static u64 notrace gic_read_count(void)
+{
+ if (mips_cm_is64)
+ return gic_read_count_64();
+
+ return gic_read_count_2x32();
+}
+
static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
{
int cpu = cpumask_first(evt->cpumask);
@@ -228,6 +239,10 @@ static int __init gic_clocksource_of_init(struct device_node *node)
/* And finally start the counter */
clear_gic_config(GIC_CONFIG_COUNTSTOP);

+ sched_clock_register(mips_cm_is64 ?
+ gic_read_count_64 : gic_read_count_2x32,
+ 64, gic_frequency);
+
return 0;
}
TIMER_OF_DECLARE(mips_gic_timer, "mti,gic-timer",
--
2.25.1
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