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83d1ffb9 LG |
1 | /** @file\r |
2 | ACPI Timer implements one instance of Timer Library.\r | |
3 | \r | |
62b8b5be | 4 | Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.<BR>\r |
83d1ffb9 LG |
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 | |
fd501a79 | 15 | #include <PiDxe.h>\r |
83d1ffb9 LG |
16 | #include <Library/TimerLib.h>\r |
17 | #include <Library/BaseLib.h>\r | |
fd501a79 LG |
18 | #include <Library/HobLib.h>\r |
19 | \r | |
20 | extern GUID mFrequencyHobGuid;\r | |
21 | \r | |
22 | /**\r | |
23 | The constructor function enables ACPI IO space.\r | |
24 | \r | |
25 | If ACPI I/O space not enabled, this function will enable it.\r | |
26 | It will always return RETURN_SUCCESS.\r | |
27 | \r | |
28 | @retval EFI_SUCCESS The constructor always returns RETURN_SUCCESS.\r | |
29 | \r | |
30 | **/\r | |
31 | RETURN_STATUS\r | |
32 | EFIAPI\r | |
33 | AcpiTimerLibConstructor (\r | |
34 | VOID\r | |
35 | );\r | |
83d1ffb9 | 36 | \r |
62b8b5be SZ |
37 | /**\r |
38 | Calculate TSC frequency.\r | |
39 | \r | |
40 | The TSC counting frequency is determined by comparing how far it counts\r | |
a012df5e SZ |
41 | during a 101.4 us period as determined by the ACPI timer.\r |
42 | The ACPI timer is used because it counts at a known frequency.\r | |
43 | The TSC is sampled, followed by waiting 363 counts of the ACPI timer,\r | |
44 | or 101.4 us. The TSC is then sampled again. The difference multiplied by\r | |
45 | 9861 is the TSC frequency. There will be a small error because of the\r | |
46 | overhead of reading the ACPI timer. An attempt is made to determine and\r | |
47 | compensate for this error.\r | |
62b8b5be SZ |
48 | \r |
49 | @return The number of TSC counts per second.\r | |
50 | \r | |
51 | **/\r | |
52 | UINT64\r | |
53 | InternalCalculateTscFrequency (\r | |
54 | VOID\r | |
55 | );\r | |
56 | \r | |
83d1ffb9 LG |
57 | //\r |
58 | // Cached performance counter frequency\r | |
59 | //\r | |
60 | UINT64 mPerformanceCounterFrequency = 0;\r | |
61 | \r | |
62 | /**\r | |
63 | Internal function to retrieves the 64-bit frequency in Hz.\r | |
64 | \r | |
65 | Internal function to retrieves the 64-bit frequency in Hz.\r | |
66 | \r | |
67 | @return The frequency in Hz.\r | |
68 | \r | |
69 | **/\r | |
70 | UINT64\r | |
71 | InternalGetPerformanceCounterFrequency (\r | |
72 | VOID\r | |
73 | ) \r | |
74 | {\r | |
fd501a79 LG |
75 | return mPerformanceCounterFrequency;\r |
76 | }\r | |
77 | \r | |
78 | /**\r | |
79 | The constructor function enables ACPI IO space, and caches PerformanceCounterFrequency. \r | |
80 | \r | |
81 | @param ImageHandle The firmware allocated handle for the EFI image.\r | |
82 | @param SystemTable A pointer to the EFI System Table.\r | |
83 | \r | |
84 | @retval EFI_SUCCESS The constructor always returns RETURN_SUCCESS.\r | |
85 | \r | |
86 | **/\r | |
87 | EFI_STATUS\r | |
88 | EFIAPI\r | |
89 | DxeAcpiTimerLibConstructor (\r | |
90 | IN EFI_HANDLE ImageHandle,\r | |
91 | IN EFI_SYSTEM_TABLE *SystemTable\r | |
92 | )\r | |
93 | {\r | |
94 | EFI_HOB_GUID_TYPE *GuidHob;\r | |
95 | \r | |
96 | //\r | |
97 | // Enable ACPI IO space.\r | |
98 | //\r | |
99 | AcpiTimerLibConstructor ();\r | |
100 | \r | |
101 | //\r | |
102 | // Initialize PerformanceCounterFrequency\r | |
103 | //\r | |
104 | GuidHob = GetFirstGuidHob (&mFrequencyHobGuid);\r | |
105 | if (GuidHob != NULL) {\r | |
106 | mPerformanceCounterFrequency = *(UINT64*)GET_GUID_HOB_DATA (GuidHob);\r | |
107 | } else {\r | |
62b8b5be | 108 | mPerformanceCounterFrequency = InternalCalculateTscFrequency ();\r |
83d1ffb9 | 109 | }\r |
fd501a79 LG |
110 | \r |
111 | return EFI_SUCCESS;\r | |
83d1ffb9 | 112 | }\r |