Subject: [PATCH] clocksource: qcom: Implement read_current_timer for udelay

From: [email-masked] (Stephen Boyd)
Date: Tue, 13 May 2014 16:01:00 -0700

Setup the same timer used as the clocksource to be used as the
read_current_timer implementation. This allows us to support a
stable udelay implementation on MSMs where it's possible for the
CPUs to scale speeds independently of one another.

Signed-off-by: Stephen Boyd <[email-masked]>
---
 drivers/clocksource/qcom-timer.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/clocksource/qcom-timer.c b/drivers/clocksource/qcom-timer.c
index e807acf4c665..8d115db1e651 100644
--- a/drivers/clocksource/qcom-timer.c
+++ b/drivers/clocksource/qcom-timer.c
@@ -26,6 +26,8 @@
 #include <linux/of_irq.h>
 #include <linux/sched_clock.h>
 
+#include <asm/delay.h>
+
 #define TIMER_MATCH_VAL			0x0000
 #define TIMER_COUNT_VAL			0x0004
 #define TIMER_ENABLE			0x0008
@@ -179,6 +181,15 @@ static u64 notrace msm_sched_clock_read(void)
 	return msm_clocksource.read(&msm_clocksource);
 }
 
+static unsigned long msm_read_current_timer(void)
+{
+	return msm_clocksource.read(&msm_clocksource);
+}
+
+static struct delay_timer msm_delay_timer = {
+	.read_current_timer = msm_read_current_timer,
+};
+
 static void __init msm_timer_init(u32 dgt_hz, int sched_bits, int irq,
 				  bool percpu)
 {
@@ -217,6 +228,8 @@ err:
 	if (res)
 		pr_err("clocksource_register failed\n");
 	sched_clock_register(msm_sched_clock_read, sched_bits, dgt_hz);
+	msm_delay_timer.freq = dgt_hz;
+	register_current_timer_delay(&msm_delay_timer);
 }
 
 #ifdef CONFIG_ARCH_QCOM
-- 
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