PcAtChipsetPkg: Add PeiAcpiTimerLib to save Frequency in HOB

[mirror_edk2.git] / PcAtChipsetPkg / Library / AcpiTimerLib / AcpiTimerLib.c

diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
index e6fea231123d9740964fa24b08ba9bc8b92aec19..2f3cb4bca4b5913430ac4e1f6dfbfed99ced21a4 100644 (file)
--- a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
+++ b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
@@ -1,7 +1,7 @@
 /** @file\r
   ACPI Timer implements one instance of Timer Library.\r
 \r
-  Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.<BR>\r
+  Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>\r
   This program and the accompanying materials\r
   are licensed and made available under the terms and conditions of the BSD License\r
   which accompanies this distribution.  The full text of the license may be found at\r
@@ -21,6 +21,8 @@
 #include <Library/DebugLib.h>\r
 #include <IndustryStandard/Acpi.h>\r
 \r
+GUID mFrequencyHobGuid = { 0x3fca54f6, 0xe1a2, 0x4b20, { 0xbe, 0x76, 0x92, 0x6b, 0x4b, 0x48, 0xbf, 0xaa }};\r
+\r
 /**\r
   Internal function to retrieves the 64-bit frequency in Hz.\r
 \r
@@ -162,14 +164,14 @@ InternalAcpiDelay (
     //\r
     // The target timer count is calculated here\r
     //\r
-    Ticks = IoRead32 (Port) + Delay;\r
+    Ticks = IoBitFieldRead32 (Port, 0, 23) + Delay;\r
     Delay = BIT22;\r
     //\r
     // Wait until time out\r
     // Delay >= 2^23 could not be handled by this function\r
     // Timer wrap-arounds are handled correctly by this function\r
     //\r
-    while (((Ticks - IoRead32 (Port)) & BIT23) == 0) {\r
+    while (((Ticks - IoBitFieldRead32 (Port, 0, 23)) & BIT23) == 0) {\r
       CpuPause ();\r
     }\r
   } while (Times-- > 0);\r
@@ -340,13 +342,13 @@ GetTimeInNanoSecond (
   Calculate TSC frequency.\r
 \r
   The TSC counting frequency is determined by comparing how far it counts\r
-  during a 100us period as determined by the ACPI timer. The ACPI timer is\r
-  used because it counts at a known frequency.\r
-  The TSC is sampled, followed by waiting for ACPI_TIMER_FREQUENCY / 10000\r
-  clocks of the ACPI timer, or 100us. The TSC is then sampled again. The\r
-  difference multiplied by 10000 is the TSC frequency. There will be a small\r
-  error because of the overhead of reading the ACPI timer. An attempt is\r
-  made to determine and compensate for this error.\r
+  during a 101.4 us period as determined by the ACPI timer.\r
+  The ACPI timer is used because it counts at a known frequency.\r
+  The TSC is sampled, followed by waiting 363 counts of the ACPI timer,\r
+  or 101.4 us. The TSC is then sampled again. The difference multiplied by\r
+  9861 is the TSC frequency. There will be a small error because of the\r
+  overhead of reading the ACPI timer. An attempt is made to determine and\r
+  compensate for this error.\r
 \r
   @return The number of TSC counts per second.\r
 \r
@@ -366,22 +368,28 @@ InternalCalculateTscFrequency (
   InterruptState = SaveAndDisableInterrupts ();\r
 \r
   TimerAddr = InternalAcpiGetAcpiTimerIoPort ();\r
-  Ticks = IoRead32 (TimerAddr) + (ACPI_TIMER_FREQUENCY / 10000);    // Set Ticks to 100us in the future\r
+  //\r
+  // Compute the number of ticks to wait to measure TSC frequency.\r
+  // Use 363 * 9861 = 3579543 Hz which is within 2 Hz of ACPI_TIMER_FREQUENCY.\r
+  // 363 counts is a calibration time of 101.4 uS.\r
+  //\r
+  Ticks = IoBitFieldRead32 (TimerAddr, 0, 23) + 363;\r
 \r
   StartTSC = AsmReadTsc ();                                         // Get base value for the TSC\r
   //\r
-  // Wait until the ACPI timer has counted 100us.\r
+  // Wait until the ACPI timer has counted 101.4 us.\r
   // Timer wrap-arounds are handled correctly by this function.\r
-  // When the current ACPI timer value is greater than 'Ticks', the while loop will exit.\r
+  // When the current ACPI timer value is greater than 'Ticks',\r
+  // the while loop will exit.\r
   //\r
-  while (((Ticks - IoRead32 (TimerAddr)) & BIT23) == 0) {\r
+  while (((Ticks - IoBitFieldRead32 (TimerAddr, 0, 23)) & BIT23) == 0) {\r
     CpuPause();\r
   }\r
-  EndTSC = AsmReadTsc ();                                           // TSC value 100us later\r
+  EndTSC = AsmReadTsc ();                                           // TSC value 101.4 us later\r
 \r
   TscFrequency = MultU64x32 (\r
-                   (EndTSC - StartTSC),                             // Number of TSC counts in 100us\r
-                   10000                                            // Number of 100us in a second\r
+                   (EndTSC - StartTSC),                             // Number of TSC counts in 101.4 us\r
+                   9861                                             // Number of 101.4 us in a second\r
                    );\r
 \r
   SetInterruptState (InterruptState);\r