gpu: nvgpu: add a simple time API

Add nvgpu_current_time_ms() to return a time from a monotonic clock
source in milliseconds. The start time is unspecified; this API is meant
to be used for duration measurements.

Jira NVGPU-83

Change-Id: I135c8ee88283149422a68d5fa859241eebbd6459
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: http://git-master/r/1503001
Reviewed-by: Deepak Nibade <dnibade@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

2 files changed, 19 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/timers.c b/drivers/gpu/nvgpu/common/linux/timers.c
index efd04557..140ae80e 100644
--- a/drivers/gpu/nvgpu/common/linux/timers.c
+++ b/drivers/gpu/nvgpu/common/linux/timers.c
@@ -229,3 +229,15 @@ void nvgpu_msleep(unsigned int msecs)
 {
         msleep(msecs);
 }
+
+/**
+ * nvgpu_current_time_ms - Time in milliseconds from a monotonic clock.
+ *
+ * Return a clock in millisecond units. The start time of the clock is
+ * unspecified; the time returned can be compared with older ones to measure
+ * durations. The source clock does not jump when the system clock is adjusted.
+ */
+s64 nvgpu_current_time_ms(void)
+{
+        return ktime_to_ms(ktime_get());
+}
diff --git a/drivers/gpu/nvgpu/include/nvgpu/timers.h b/drivers/gpu/nvgpu/include/nvgpu/timers.h
index 0aadd0df..be903e54 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/timers.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/timers.h
@@ -17,6 +17,8 @@
 #ifndef __NVGPU_TIMERS_H__
 #define __NVGPU_TIMERS_H__
 
+#include <nvgpu/types.h>
+
 struct gk20a;
 
 /*
@@ -97,4 +99,9 @@ void nvgpu_msleep(unsigned int msecs);
 void nvgpu_usleep_range(unsigned int min_us, unsigned int max_us);
 void nvgpu_udelay(unsigned int usecs);
 
+/*
+ * Timekeeping.
+ */
+s64 nvgpu_current_time_ms(void);
+
 #endif