From 96a80ae3ce24905539e0fbd55b398e4d8ec9f410 Mon Sep 17 00:00:00 2001
From: Sami Mujawar <sami.mujawar@arm.com>
Date: Thu, 3 Mar 2016 15:28:16 +0000
Subject: [PATCH] ArmPkg/ArmArchTimerLib: add GetTimeInNanoSecond() to
 ArmArchTimerLib

FirmwarePerformanceDxe.c utilizes the Timer Library function
GetTimeInNanoSecond() which was not implemented by the ArmArchTimerLib.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Evan Lloyd <evan.lloyd@arm.com>
Reviewed-by: Ryan Harkin <ryan.harkin@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 .../Library/ArmArchTimerLib/ArmArchTimerLib.c | 51 ++++++++++++++++++-
 1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c b/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c
index 4361905e14..1be90c515c 100644
--- a/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c
+++ b/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c
@@ -1,7 +1,7 @@
 /** @file
   Generic ARM implementation of TimerLib.h
 
-  Copyright (c) 2011-2014, ARM Limited. All rights reserved.
+  Copyright (c) 2011-2016, ARM Limited. All rights reserved.
 
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
@@ -242,3 +242,52 @@ GetPerformanceCounterProperties (
 
   return (UINT64)ArmGenericTimerGetTimerFreq ();
 }
+
+/**
+  Converts elapsed ticks of performance counter to time in nanoseconds.
+
+  This function converts the elapsed ticks of running performance counter to
+  time value in unit of nanoseconds.
+
+  @param  Ticks     The number of elapsed ticks of running performance counter.
+
+  @return The elapsed time in nanoseconds.
+
+**/
+UINT64
+EFIAPI
+GetTimeInNanoSecond (
+  IN      UINT64                     Ticks
+  )
+{
+  UINT64  NanoSeconds;
+  UINT32  Remainder;
+  UINT32  TimerFreq;
+
+  TimerFreq = GetPlatformTimerFreq ();
+  //
+  //          Ticks
+  // Time = --------- x 1,000,000,000
+  //        Frequency
+  //
+  NanoSeconds = MultU64xN (
+                  DivU64x32Remainder (
+                    Ticks,
+                    TimerFreq,
+                    &Remainder),
+                  1000000000U
+                  );
+
+  //
+  // Frequency < 0x100000000, so Remainder < 0x100000000, then (Remainder * 1,000,000,000)
+  // will not overflow 64-bit.
+  //
+  NanoSeconds += DivU64x32 (
+                   MultU64xN (
+                     (UINT64) Remainder,
+                     1000000000U),
+                   TimerFreq
+                   );
+
+  return NanoSeconds;
+}