[PATCH v2 5/6] clocksource: mips-gic-timer: Register as sched_clock

[Sergey.Semin]

From: Paul Burton <paulburton@xxxxxxxxxx>

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@xxxxxxxxxx>
Cc: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
Cc: Alexey Malahov <Alexey.Malahov@xxxxxxxxxxxxxxxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: devicetree@xxxxxxxxxxxxxxx
---
 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