1 /** @file
2 Implementation of Timestamp Protocol using UEFI APIs.
3
4 Copyright (c) 2013, Intel Corporation. All rights reserved.<BR>
5 This program and the accompanying materials
6 are licensed and made available under the terms and conditions of the BSD License
7 which accompanies this distribution. The full text of the license may be found at
8 http://opensource.org/licenses/bsd-license.php
9
10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
12
13 **/
14
15 #include <Uefi.h>
16 #include <Library/DebugLib.h>
17 #include <Library/UefiDriverEntryPoint.h>
18 #include <Library/UefiBootServicesTableLib.h>
19 #include <Library/TimerLib.h>
20 #include <Library/BaseMemoryLib.h>
21 #include <Protocol/Timestamp.h>
22
23 //
24 // The StartValue in TimerLib
25 //
26 UINT64 mTimerLibStartValue = 0;
27
28 //
29 // The EndValue in TimerLib
30 //
31 UINT64 mTimerLibEndValue = 0;
32
33 //
34 // The properties of timestamp
35 //
36 EFI_TIMESTAMP_PROPERTIES mTimestampProperties = {
37 0,
38 0
39 };
40
41 /**
42 Retrieves the current value of a 64-bit free running timestamp counter.
43
44 The counter shall count up in proportion to the amount of time that has passed. The counter value
45 will always roll over to zero. The properties of the counter can be retrieved from GetProperties().
46 The caller should be prepared for the function to return the same value twice across successive calls.
47 The counter value will not go backwards other than when wrapping, as defined by EndValue in GetProperties().
48 The frequency of the returned timestamp counter value must remain constant. Power management operations that
49 affect clocking must not change the returned counter frequency. The quantization of counter value updates may
50 vary as long as the value reflecting time passed remains consistent.
51
52 @retval The current value of the free running timestamp counter.
53
54 **/
55 UINT64
56 EFIAPI
TimestampDriverGetTimestamp(VOID)57 TimestampDriverGetTimestamp (
58 VOID
59 )
60 {
61 //
62 // The timestamp of Timestamp Protocol
63 //
64 UINT64 TimestampValue;
65 TimestampValue = 0;
66
67 //
68 // Get the timestamp
69 //
70 if (mTimerLibStartValue > mTimerLibEndValue) {
71 TimestampValue = mTimerLibStartValue - GetPerformanceCounter();
72 } else {
73 TimestampValue = GetPerformanceCounter() - mTimerLibStartValue;
74 }
75
76 return TimestampValue;
77 }
78
79 /**
80 Obtains timestamp counter properties including frequency and value limits.
81
82 @param[out] Properties The properties of the timestamp counter.
83
84 @retval EFI_SUCCESS The properties were successfully retrieved.
85 @retval EFI_DEVICE_ERROR An error occurred trying to retrieve the properties of the timestamp
86 counter subsystem. Properties is not pedated.
87 @retval EFI_INVALID_PARAMETER Properties is NULL.
88
89 **/
90 EFI_STATUS
91 EFIAPI
TimestampDriverGetProperties(OUT EFI_TIMESTAMP_PROPERTIES * Properties)92 TimestampDriverGetProperties(
93 OUT EFI_TIMESTAMP_PROPERTIES *Properties
94 )
95 {
96 if (Properties == NULL) {
97 return EFI_INVALID_PARAMETER;
98 }
99
100 //
101 // Get timestamp properties
102 //
103 CopyMem((VOID *) Properties, (VOID *) &mTimestampProperties, sizeof (mTimestampProperties));
104
105 return EFI_SUCCESS;
106 }
107
108 //
109 // The Timestamp Protocol instance produced by this driver
110 //
111 EFI_TIMESTAMP_PROTOCOL mTimestamp = {
112 TimestampDriverGetTimestamp,
113 TimestampDriverGetProperties
114 };
115
116 /**
117 Entry point of the Timestamp Protocol driver.
118
119 @param ImageHandle The image handle of this driver.
120 @param SystemTable The pointer of EFI_SYSTEM_TABLE.
121
122 @retval EFI_SUCCESS Watchdog Timer Architectural Protocol successfully installed.
123
124 **/
125 EFI_STATUS
126 EFIAPI
TimestampDriverInitialize(IN EFI_HANDLE ImageHandle,IN EFI_SYSTEM_TABLE * SystemTable)127 TimestampDriverInitialize (
128 IN EFI_HANDLE ImageHandle,
129 IN EFI_SYSTEM_TABLE *SystemTable
130 )
131 {
132 EFI_STATUS Status;
133
134 EFI_HANDLE TimestampHandle;
135 TimestampHandle = NULL;
136
137 //
138 // Get the start value, end value and frequency in Timerlib
139 //
140 mTimestampProperties.Frequency = GetPerformanceCounterProperties(&mTimerLibStartValue, &mTimerLibEndValue);
141
142 //
143 // Set the EndValue
144 //
145 if (mTimerLibEndValue > mTimerLibStartValue) {
146 mTimestampProperties.EndValue = mTimerLibEndValue - mTimerLibStartValue;
147 } else {
148 mTimestampProperties.EndValue = mTimerLibStartValue - mTimerLibEndValue;
149 }
150
151 DEBUG ((EFI_D_INFO, "TimerFrequency:0x%lx, TimerLibStartTime:0x%lx, TimerLibEndtime:0x%lx\n", mTimestampProperties.Frequency, mTimerLibStartValue, mTimerLibEndValue));
152
153 //
154 // Install the Timestamp Protocol onto a new handle
155 //
156 Status = gBS->InstallMultipleProtocolInterfaces (
157 &TimestampHandle,
158 &gEfiTimestampProtocolGuid,
159 &mTimestamp,
160 NULL
161 );
162
163 ASSERT_EFI_ERROR (Status);
164
165 return EFI_SUCCESS;
166 }
167