]>
git.proxmox.com Git - mirror_edk2.git/blob - ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c
2 Generic ARM implementation of TimerLib.h
4 Copyright (c) 2011-2013, ARM Limited. All rights reserved.
6 This program and the accompanying materials
7 are licensed and made available under the terms and conditions of the BSD License
8 which accompanies this distribution. The full text of the license may be found at
9 http://opensource.org/licenses/bsd-license.php
11 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
12 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
18 #include <Library/ArmLib.h>
19 #include <Library/BaseLib.h>
20 #include <Library/TimerLib.h>
21 #include <Library/DebugLib.h>
22 #include <Library/PcdLib.h>
23 #include <Library/ArmArchTimerLib.h>
25 #define TICKS_PER_MICRO_SEC (PcdGet32 (PcdArmArchTimerFreqInHz)/1000000U)
33 // Check if the ARM Generic Timer Extension is implemented
34 if (ArmIsArchTimerImplemented ()) {
38 // Check if Architectural Timer frequency is valid number (should not be 0)
39 ASSERT (PcdGet32 (PcdArmArchTimerFreqInHz
));
41 // Check if ticks/uS is not 0. The Architectural timer runs at constant
42 // frequency irrespective of CPU frequency. According to General Timer Ref
43 // manual lower bound of the frequency is in the range of 1-10MHz
44 ASSERT (TICKS_PER_MICRO_SEC
);
47 // Only set the frequency for ARMv7. We expect the secure firmware to have already do it
48 // If the security extensions are not implemented set Timer Frequency
49 if ((ArmReadIdPfr1 () & 0xF0) == 0x0) {
50 ArmArchTimerSetTimerFreq (PcdGet32 (PcdArmArchTimerFreqInHz
));
54 // Architectural Timer Frequency must be set in the Secure privileged(if secure extensions are supported) mode.
55 // If the reset value (0) is returned just ASSERT.
56 TimerFreq
= ArmArchTimerGetTimerFreq ();
57 ASSERT (TimerFreq
!= 0);
60 DEBUG ((EFI_D_ERROR
, "ARM Architectural Timer is not available in the CPU, hence this library can not be used.\n"));
64 return RETURN_SUCCESS
;
69 Stalls the CPU for the number of microseconds specified by MicroSeconds.
71 @param MicroSeconds The minimum number of microseconds to delay.
73 @return The value of MicroSeconds inputted.
83 UINT64 SystemCounterVal
;
85 // Calculate counter ticks that can represent requested delay
86 TimerTicks64
= MultU64x32 (MicroSeconds
, TICKS_PER_MICRO_SEC
);
88 // Read System Counter value
89 SystemCounterVal
= ArmArchTimerGetSystemCount ();
91 TimerTicks64
+= SystemCounterVal
;
93 // Wait until delay count is expired.
94 while (SystemCounterVal
< TimerTicks64
) {
95 SystemCounterVal
= ArmArchTimerGetSystemCount ();
103 Stalls the CPU for at least the given number of nanoseconds.
105 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
107 When the timer frequency is 1MHz, each tick corresponds to 1 microsecond.
108 Therefore, the nanosecond delay will be rounded up to the nearest 1 microsecond.
110 @param NanoSeconds The minimum number of nanoseconds to delay.
112 @return The value of NanoSeconds inputed.
123 // Round up to 1us Tick Number
124 MicroSeconds
= NanoSeconds
/ 1000;
125 MicroSeconds
+= ((NanoSeconds
% 1000) == 0) ? 0 : 1;
127 MicroSecondDelay (MicroSeconds
);
133 Retrieves the current value of a 64-bit free running performance counter.
135 The counter can either count up by 1 or count down by 1. If the physical
136 performance counter counts by a larger increment, then the counter values
137 must be translated. The properties of the counter can be retrieved from
138 GetPerformanceCounterProperties().
140 @return The current value of the free running performance counter.
145 GetPerformanceCounter (
149 // Just return the value of system count
150 return ArmArchTimerGetSystemCount ();
154 Retrieves the 64-bit frequency in Hz and the range of performance counter
157 If StartValue is not NULL, then the value that the performance counter starts
158 with immediately after is it rolls over is returned in StartValue. If
159 EndValue is not NULL, then the value that the performance counter end with
160 immediately before it rolls over is returned in EndValue. The 64-bit
161 frequency of the performance counter in Hz is always returned. If StartValue
162 is less than EndValue, then the performance counter counts up. If StartValue
163 is greater than EndValue, then the performance counter counts down. For
164 example, a 64-bit free running counter that counts up would have a StartValue
165 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
166 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
168 @param StartValue The value the performance counter starts with when it
170 @param EndValue The value that the performance counter ends with before
173 @return The frequency in Hz.
178 GetPerformanceCounterProperties (
179 OUT UINT64
*StartValue
, OPTIONAL
180 OUT UINT64
*EndValue OPTIONAL
183 if (StartValue
!= NULL
) {
184 // Timer starts with the reload value
185 *StartValue
= (UINT64
)0ULL ;
188 if (EndValue
!= NULL
) {
189 // Timer counts down to 0x0
190 *EndValue
= 0xFFFFFFFFFFFFFFFFUL
;
193 return (UINT64
)ArmArchTimerGetTimerFreq ();