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045c8b9a | 1 | /** @file\r |
2 | Produces the Metronome Architectural Protocol on top of Timer Library.\r | |
fbfd91e6 | 3 | \r |
4 | This is a generic implementation of the Metronome Architectural Protocol that\r | |
5 | layers on top of an instance of the Timer Library. The Timer Library provides\r | |
6 | functions for nanosecond and microsecond delays. This generic implementation\r | |
7 | produces a fixed TickPeriod of 1 100ns unit, and when the WaitForTick() service\r | |
8 | is called, the number of ticks passed in is converted to either nanosecond or\r | |
9 | microsecond units. If the number of ticks is small, then nanoseconds are used.\r | |
10 | If the number of ticks is large, then microseconds are used. This prevents\r | |
11 | overflows that could occur for long delays if only nanoseconds were used and also\r | |
d1102dba | 12 | provides the greatest accuracy for small delays.\r |
fbfd91e6 | 13 | \r |
d1102dba LG |
14 | Copyright (c) 2008 - 2018, Intel Corporation. All rights reserved.<BR>\r |
15 | This program and the accompanying materials\r | |
16 | are licensed and made available under the terms and conditions of the BSD License\r | |
17 | which accompanies this distribution. The full text of the license may be found at\r | |
18 | http://opensource.org/licenses/bsd-license.php\r | |
19 | \r | |
20 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r | |
21 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r | |
045c8b9a | 22 | \r |
23 | **/\r | |
fbfd91e6 | 24 | \r |
96268f28 | 25 | #include "Metronome.h"\r |
26 | \r | |
fbfd91e6 | 27 | //\r |
28 | // Handle for the Metronome Architectural Protocol instance produced by this driver\r | |
29 | //\r | |
30 | EFI_HANDLE mMetronomeHandle = NULL;\r | |
31 | \r | |
32 | //\r | |
33 | // The Metronome Architectural Protocol instance produced by this driver\r | |
34 | //\r | |
35 | EFI_METRONOME_ARCH_PROTOCOL mMetronome = {\r | |
36 | WaitForTick,\r | |
9738656b | 37 | 1 // TickPeriod = 1*100 ns units\r |
fbfd91e6 | 38 | };\r |
39 | \r | |
40 | /**\r | |
92733d45 | 41 | Waits for the specified number of ticks.\r |
d1102dba | 42 | \r |
92733d45 | 43 | This function implements EFI_METRONOME_ARCH_PROTOCOL.WaitForTick().\r |
d1102dba LG |
44 | The WaitForTick() function waits for the number of ticks specified by\r |
45 | TickNumber from a known time source in the platform. If TickNumber of\r | |
46 | ticks are detected, then EFI_SUCCESS is returned. The actual time passed\r | |
47 | between entry of this function and the first tick is between 0 and\r | |
48 | TickPeriod 100 nS units. If you want to guarantee that at least TickPeriod\r | |
49 | time has elapsed, wait for two ticks. This function waits for a hardware\r | |
50 | event to determine when a tick occurs. It is possible for interrupt\r | |
51 | processing, or exception processing to interrupt the execution of the\r | |
52 | WaitForTick() function. Depending on the hardware source for the ticks, it\r | |
53 | is possible for a tick to be missed. This function cannot guarantee that\r | |
54 | ticks will not be missed. If a timeout occurs waiting for the specified\r | |
fbfd91e6 | 55 | number of ticks, then EFI_TIMEOUT is returned.\r |
56 | \r | |
57 | @param This The EFI_METRONOME_ARCH_PROTOCOL instance.\r | |
58 | @param TickNumber Number of ticks to wait.\r | |
59 | \r | |
60 | @retval EFI_SUCCESS The wait for the number of ticks specified by TickNumber\r | |
61 | succeeded.\r | |
62 | @retval EFI_TIMEOUT A timeout occurred waiting for the specified number of ticks.\r | |
63 | \r | |
64 | **/\r | |
65 | EFI_STATUS\r | |
66 | EFIAPI\r | |
67 | WaitForTick (\r | |
68 | IN EFI_METRONOME_ARCH_PROTOCOL *This,\r | |
69 | IN UINT32 TickNumber\r | |
70 | )\r | |
71 | {\r | |
72 | //\r | |
73 | // Check the value of TickNumber, so a 32-bit overflow can be avoided\r | |
74 | // when TickNumber of converted to nanosecond units\r | |
75 | //\r | |
76 | if (TickNumber < 10000000) {\r | |
77 | //\r | |
78 | // If TickNumber is small, then use NanoSecondDelay()\r | |
79 | //\r | |
80 | NanoSecondDelay (TickNumber * 100);\r | |
81 | } else {\r | |
82 | //\r | |
83 | // If TickNumber is large, then use MicroSecondDelay()\r | |
84 | //\r | |
85 | MicroSecondDelay (TickNumber / 10);\r | |
86 | }\r | |
87 | return EFI_SUCCESS;\r | |
88 | }\r | |
89 | \r | |
90 | /**\r | |
91 | The user Entry Point for module Metronome. The user code starts with this function.\r | |
92 | \r | |
d1102dba | 93 | @param[in] ImageHandle The firmware allocated handle for the EFI image.\r |
fbfd91e6 | 94 | @param[in] SystemTable A pointer to the EFI System Table.\r |
d1102dba | 95 | \r |
fbfd91e6 | 96 | @retval EFI_SUCCESS The entry point is executed successfully.\r |
97 | @retval other Some error occurs when executing this entry point.\r | |
98 | \r | |
99 | **/\r | |
100 | EFI_STATUS\r | |
101 | EFIAPI\r | |
102 | InstallMetronome (\r | |
103 | IN EFI_HANDLE ImageHandle,\r | |
104 | IN EFI_SYSTEM_TABLE *SystemTable\r | |
105 | )\r | |
106 | {\r | |
107 | EFI_STATUS Status;\r | |
108 | \r | |
109 | //\r | |
110 | // Make sure the Metronome Architectural Protocol is not already installed in the system\r | |
111 | //\r | |
112 | ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiMetronomeArchProtocolGuid);\r | |
113 | \r | |
114 | //\r | |
115 | // Install on a new handle\r | |
116 | //\r | |
117 | Status = gBS->InstallMultipleProtocolInterfaces (\r | |
118 | &mMetronomeHandle,\r | |
119 | &gEfiMetronomeArchProtocolGuid, &mMetronome,\r | |
120 | NULL\r | |
121 | );\r | |
122 | ASSERT_EFI_ERROR (Status);\r | |
123 | \r | |
124 | return Status;\r | |
125 | }\r |