projects / mirror_edk2.git / blame
| Commit | Line | Data |
|---|---|---|
| 034307a7 SZ |
1 | /** @file\r |
| 2 | Internal header file for TscTimerLib instances.\r | |
| 3 | \r | |
| 4 | Copyright (c) 2009 - 2011, Intel Corporation. All rights reserved.<BR>\r | |
| 5 | This program and the accompanying materials\r | |
| 6 | are licensed and made available under the terms and conditions of the BSD License\r | |
| 7 | which accompanies this distribution. The full text of the license may be found at\r | |
| 8 | http://opensource.org/licenses/bsd-license.php\r | |
| 9 | \r | |
| 10 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r | |
| 11 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r | |
| 12 | \r | |
| 13 | **/\r | |
| 14 | \r | |
| 15 | #ifndef _TSC_TIMER_LIB_INTERNAL_H_\r | |
| 16 | #define _TSC_TIMER_LIB_INTERNAL_H_\r | |
| 17 | \r | |
| 18 | #include <Ich/GenericIch.h>\r | |
| 19 | \r | |
| 20 | #include <Library/TimerLib.h>\r | |
| 21 | #include <Library/BaseLib.h>\r | |
| 22 | #include <Library/IoLib.h>\r | |
| 23 | #include <Library/PciLib.h>\r | |
| 24 | #include <Library/PcdLib.h>\r | |
| 25 | \r | |
| 26 | /** Get TSC frequency.\r | |
| 27 | \r | |
| 28 | @return The number of TSC counts per second.\r | |
| 29 | \r | |
| 30 | **/\r | |
| 31 | UINT64\r | |
| 32 | InternalGetTscFrequency (\r | |
| 33 | VOID\r | |
| 34 | );\r | |
| 35 | \r | |
| 36 | /** Calculate TSC frequency.\r | |
| 37 | \r | |
| 38 | The TSC counting frequency is determined by comparing how far it counts\r | |
| 39 | during a 1ms period as determined by the ACPI timer. The ACPI timer is\r | |
| 40 | used because it counts at a known frequency.\r | |
| 41 | If ACPI I/O space not enabled, this function will enable it. Then the\r | |
| 42 | TSC is sampled, followed by waiting for 3579 clocks of the ACPI timer, or 1ms.\r | |
| 43 | The TSC is then sampled again. The difference multiplied by 1000 is the TSC\r | |
| 44 | frequency. There will be a small error because of the overhead of reading\r | |
| 45 | the ACPI timer. An attempt is made to determine and compensate for this error.\r | |
| 46 | \r | |
| 47 | @return The number of TSC counts per second.\r | |
| 48 | \r | |
| 49 | **/\r | |
| 50 | UINT64\r | |
| 51 | InternalCalculateTscFrequency (\r | |
| 52 | VOID\r | |
| 53 | );\r | |
| 54 | \r | |
| 55 | #endif\r |