gpu: nvgpu: Improve accuracy of dGPU clk measurement

- This patch replaces "nvgpu_current_time_ms" with "nvgpu_hr_timestamp_us".
- "nvgpu_hr_timestamp_us" gives timestamp in microseconds and has better
accuracy than "nvgpu_current_time_ms" (which gives timestamp in millisecond)

Bug 200503143

Change-Id: I6a10e8e1b3e8ff842aa23f58bf2ba9344af232a6
Signed-off-by: Vaibhav Kachore <vkachore@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/2125959
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/hal/clk/clk_gv100.c

@@ -31,7 +31,7 @@
 #include <nvgpu/io.h>
 #include <nvgpu/list.h>
 #include <nvgpu/clk_arb.h>
-#include <nvgpu/timers.h>
+#include <nvgpu/soc.h>
 #include <nvgpu/gk20a.h>
 #include <nvgpu/clk.h>
 #include <nvgpu/clk_arb.h>
@@ -189,13 +189,14 @@ u32 gv100_get_rate_cntr(struct gk20a *g, struct namemap_cfg *c) {
 	/* Counter is 36bits , 32 bits on addr[0] and 4 lsb on addr[1] others zero*/
 	cntr_start = (u64)gk20a_readl(g, c->cntr.reg_cntr_addr[0]);
 	cntr_start += ((u64)gk20a_readl(g, c->cntr.reg_cntr_addr[1]) << 32);
-	start_time = (u64)nvgpu_current_time_ms();
+	start_time = (u64)nvgpu_hr_timestamp_us();
 	nvgpu_udelay(XTAL_CNTR_DELAY);
-	stop_time = (u64)nvgpu_current_time_ms();
+	stop_time = (u64)nvgpu_hr_timestamp_us();
 	cntr_stop = (u64)gk20a_readl(g, c->cntr.reg_cntr_addr[0]);
 	cntr_stop += ((u64)gk20a_readl(g, c->cntr.reg_cntr_addr[1]) << 32);
 	/*Calculate the difference with Acutal time and convert to KHz*/
-	cntr = ((u32)(cntr_stop - cntr_start) / (u32)(stop_time-start_time));
+	cntr = (u32)(((cntr_stop - cntr_start) * 1000U) /
+					(u32)(stop_time-start_time));
 	nvgpu_mutex_release(&clk->clk_mutex);
 
 	return cntr;

drivers/gpu/nvgpu/include/nvgpu/soc.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2018, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2017-2019, NVIDIA CORPORATION.  All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -34,5 +34,5 @@ bool nvgpu_is_bpmp_running(struct gk20a *g);
 bool nvgpu_is_soc_t194_a01(struct gk20a *g);
 int nvgpu_init_soc_vars(struct gk20a *g);
 void nvgpu_delay_usecs(unsigned int usecs);
-
+u64 nvgpu_us_counter(void);
 #endif /* NVGPU_SOC_H */

drivers/gpu/nvgpu/include/nvgpu/timers.h

@@ -111,6 +111,8 @@ void nvgpu_udelay(unsigned int usecs);
  */
 s64 nvgpu_current_time_ms(void);
 s64 nvgpu_current_time_ns(void);
+s64 nvgpu_current_time_us(void);
+u64 nvgpu_hr_timestamp_us(void);
 u64 nvgpu_hr_timestamp(void);
 
 #endif /* NVGPU_TIMERS_H */

drivers/gpu/nvgpu/os/linux/soc.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2018, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2017-2019, NVIDIA CORPORATION.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -127,3 +127,8 @@ int nvgpu_init_soc_vars(struct gk20a *g)
 #endif
 	return 0;
 }
+
+u64 nvgpu_us_counter(void)
+{
+	return (u64)nvgpu_current_time_us();
+}

drivers/gpu/nvgpu/os/linux/timers.c

@@ -242,6 +242,18 @@ s64 nvgpu_current_time_ms(void)
 	return ktime_to_ms(ktime_get());
 }
 
+/**
+ * nvgpu_current_time_us - Time in microseconds from a monotonic clock.
+ *
+ * Return a clock in microsecond 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_us(void)
+{
+	return ktime_to_us(ktime_get());
+}
+
 /**
  * nvgpu_current_time_ns - Time in nanoseconds from a monotonic clock.
  *
@@ -254,6 +266,18 @@ s64 nvgpu_current_time_ns(void)
 	return ktime_to_ns(ktime_get());
 }
 
+/**
+ * nvgpu_hr_timestamp_us - Time in microseconds from a monotonic clock.
+ *
+ * Return a clock in microsecond 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.
+ */
+u64 nvgpu_hr_timestamp_us(void)
+{
+	return nvgpu_us_counter();
+}
+
 /**
  * nvgpu_hr_timestamp - Opaque 'high resolution' time stamp.
  *

drivers/gpu/nvgpu/os/posix/soc.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2018-2019, NVIDIA CORPORATION.  All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -20,6 +20,7 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#include <nvgpu/timers.h>
 #include <nvgpu/soc.h>
 
 bool nvgpu_platform_is_silicon(struct gk20a *g)
@@ -55,3 +56,8 @@ bool nvgpu_is_soc_t194_a01(struct gk20a *g)
 void nvgpu_delay_usecs(unsigned int usecs)
 {
 }
+
+u64 nvgpu_us_counter(void)
+{
+	return (u64)nvgpu_current_time_us();
+}

drivers/gpu/nvgpu/os/posix/timers.c

@@ -34,7 +34,7 @@
 #define NSEC_PER_MSEC   1000000
 #define NSEC_PER_SEC    1000000000
 
-static inline s64 nvgpu_current_time_us(void)
+s64 nvgpu_current_time_us(void)
 {
 	struct timeval now;
 	s64 time_now;
@@ -248,3 +248,8 @@ u64 nvgpu_hr_timestamp(void)
 {
 	return (u64)nvgpu_current_time_us();
 }
+
+u64 nvgpu_hr_timestamp_us(void)
+{
+	return nvgpu_us_counter();
+}