projects / mirror_edk2.git / blame
| Commit | Line | Data |
|---|---|---|
| 034307a7 SZ |
1 | /** @file\r |
| 2 | A Pei Timer Library implementation which uses the Time Stamp Counter in the processor.\r | |
| 3 | \r | |
| 4 | For Pentium 4 processors, Intel Xeon processors (family [0FH], models [03H and higher]);\r | |
| 5 | for Intel Core Solo and Intel Core Duo processors (family [06H], model [0EH]);\r | |
| 6 | for the Intel Xeon processor 5100 series and Intel Core 2 Duo processors (family [06H], model [0FH]);\r | |
| 7 | for Intel Core 2 and Intel Xeon processors (family [06H], display_model [17H]);\r | |
| 8 | for Intel Atom processors (family [06H], display_model [1CH]):\r | |
| 9 | the time-stamp counter increments at a constant rate.\r | |
| 10 | That rate may be set by the maximum core-clock to bus-clock ratio of the processor or may be set by\r | |
| 11 | the maximum resolved frequency at which the processor is booted. The maximum resolved frequency may\r | |
| 12 | differ from the maximum qualified frequency of the processor.\r | |
| 13 | \r | |
| 14 | The specific processor configuration determines the behavior. Constant TSC behavior ensures that the\r | |
| 15 | duration of each clock tick is uniform and supports the use of the TSC as a wall clock timer even if\r | |
| 16 | the processor core changes frequency. This is the architectural behavior moving forward.\r | |
| 17 | \r | |
| 18 | A Processor's support for invariant TSC is indicated by CPUID.0x80000007.EDX[8].\r | |
| 19 | \r | |
| 20 | Copyright (c) 2009 - 2011, Intel Corporation. All rights reserved.<BR>\r | |
| 21 | This program and the accompanying materials\r | |
| 22 | are licensed and made available under the terms and conditions of the BSD License\r | |
| 23 | which accompanies this distribution. The full text of the license may be found at\r | |
| 24 | http://opensource.org/licenses/bsd-license.php\r | |
| 25 | \r | |
| 26 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r | |
| 27 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r | |
| 28 | \r | |
| 29 | **/\r | |
| 30 | \r | |
| 31 | #include <PiPei.h>\r | |
| 32 | #include <Library/HobLib.h>\r | |
| 33 | #include <Guid/TscFrequency.h>\r | |
| 34 | #include "TscTimerLibInternal.h"\r | |
| 35 | \r | |
| 36 | /** Get TSC frequency from TSC frequency GUID HOB, if the HOB is not found, build it.\r | |
| 37 | \r | |
| 38 | @return The number of TSC counts per second.\r | |
| 39 | \r | |
| 40 | **/\r | |
| 41 | UINT64\r | |
| 42 | InternalGetTscFrequency (\r | |
| 43 | VOID\r | |
| 44 | )\r | |
| 45 | {\r | |
| 46 | EFI_HOB_GUID_TYPE *GuidHob;\r | |
| 47 | VOID *DataInHob;\r | |
| 48 | UINT64 TscFrequency;\r | |
| 49 | \r | |
| 50 | //\r | |
| 51 | // Get TSC frequency from TSC frequency GUID HOB.\r | |
| 52 | //\r | |
| 53 | GuidHob = GetFirstGuidHob (&gEfiTscFrequencyGuid);\r | |
| 54 | if (GuidHob != NULL) {\r | |
| 55 | DataInHob = GET_GUID_HOB_DATA (GuidHob);\r | |
| 56 | TscFrequency = * (UINT64 *) DataInHob;\r | |
| 57 | return TscFrequency;\r | |
| 58 | }\r | |
| 59 | \r | |
| 60 | //\r | |
| 61 | // TSC frequency GUID HOB is not found, build it.\r | |
| 62 | //\r | |
| 63 | \r | |
| 64 | TscFrequency = InternalCalculateTscFrequency ();\r | |
| 65 | //\r | |
| 66 | // TscFrequency is now equal to the number of TSC counts per second, build GUID HOB for it.\r | |
| 67 | //\r | |
| 68 | BuildGuidDataHob (\r | |
| 69 | &gEfiTscFrequencyGuid,\r | |
| 70 | &TscFrequency,\r | |
| 71 | sizeof (UINT64)\r | |
| 72 | );\r | |
| 73 | \r | |
| 74 | return TscFrequency;\r | |
| 75 | }\r | |
| 76 | \r |