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git.proxmox.com Git - mirror_edk2.git/blob - UefiCpuPkg/Library/SecPeiDxeTimerLibUefiCpu/X86TimerLib.c
2 Timer Library functions built upon local APIC on IA32/x64.
4 This library uses the local APIC library so that it supports x2APIC mode.
6 Copyright (c) 2010 - 2013, Intel Corporation. All rights reserved.<BR>
7 This program and the accompanying materials
8 are licensed and made available under the terms and conditions of the BSD License
9 which accompanies this distribution. The full text of the license may be found at
10 http://opensource.org/licenses/bsd-license.php.
12 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
13 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
18 #include <Library/TimerLib.h>
19 #include <Library/BaseLib.h>
20 #include <Library/PcdLib.h>
21 #include <Library/DebugLib.h>
22 #include <Library/LocalApicLib.h>
25 Internal function to return the frequency of the local APIC timer.
27 @return The frequency of the timer in Hz.
32 InternalX86GetTimerFrequency (
38 GetApicTimerState (&Divisor
, NULL
, NULL
);
39 return PcdGet32(PcdFSBClock
) / (UINT32
)Divisor
;
43 Stalls the CPU for at least the given number of ticks.
45 Stalls the CPU for at least the given number of ticks. It's invoked by
46 MicroSecondDelay() and NanoSecondDelay().
48 @param Delay A period of time to delay in ticks.
63 // In case Delay is too larger, separate it into several small delay slot.
64 // Devided Delay by half value of Init Count is to avoid Delay close to
65 // the Init Count, timeout maybe missing if the time consuming between 2
66 // GetApicTimerCurrentCount() invoking is larger than the time gap between
67 // Delay and the Init Count.
69 InitCount
= GetApicTimerInitCount ();
70 Times
= Delay
/ (InitCount
/ 2);
71 Delay
= Delay
% (InitCount
/ 2);
74 // Get Start Tick and do delay
76 StartTick
= GetApicTimerCurrentCount ();
79 // Wait until time out by Delay value
84 // Get Ticks from Start to Current.
86 Ticks
= StartTick
- GetApicTimerCurrentCount ();
88 // Ticks < 0 means Timer wrap-arounds happens.
93 } while ((UINT32
)Ticks
< Delay
);
96 // Update StartTick and Delay for next delay slot
98 StartTick
-= (StartTick
> Delay
) ? Delay
: (Delay
- InitCount
);
99 Delay
= InitCount
/ 2;
100 } while (Times
-- > 0);
104 Stalls the CPU for at least the given number of microseconds.
106 Stalls the CPU for the number of microseconds specified by MicroSeconds.
108 @param MicroSeconds The minimum number of microseconds to delay.
110 @return The value of MicroSeconds inputted.
116 IN UINTN MicroSeconds
122 InternalX86GetTimerFrequency (),
132 Stalls the CPU for at least the given number of nanoseconds.
134 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
136 @param NanoSeconds The minimum number of nanoseconds to delay.
138 @return The value of NanoSeconds inputted.
150 InternalX86GetTimerFrequency (),
160 Retrieves the current value of a 64-bit free running performance counter.
162 The counter can either count up by 1 or count down by 1. If the physical
163 performance counter counts by a larger increment, then the counter values
164 must be translated. The properties of the counter can be retrieved from
165 GetPerformanceCounterProperties().
167 @return The current value of the free running performance counter.
172 GetPerformanceCounter (
176 return (UINT64
)GetApicTimerCurrentCount ();
180 Retrieves the 64-bit frequency in Hz and the range of performance counter
183 If StartValue is not NULL, then the value that the performance counter starts
184 with immediately after is it rolls over is returned in StartValue. If
185 EndValue is not NULL, then the value that the performance counter end with
186 immediately before it rolls over is returned in EndValue. The 64-bit
187 frequency of the performance counter in Hz is always returned. If StartValue
188 is less than EndValue, then the performance counter counts up. If StartValue
189 is greater than EndValue, then the performance counter counts down. For
190 example, a 64-bit free running counter that counts up would have a StartValue
191 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
192 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
194 @param StartValue The value the performance counter starts with when it
196 @param EndValue The value that the performance counter ends with before
199 @return The frequency in Hz.
204 GetPerformanceCounterProperties (
205 OUT UINT64
*StartValue
, OPTIONAL
206 OUT UINT64
*EndValue OPTIONAL
209 if (StartValue
!= NULL
) {
210 *StartValue
= (UINT64
)GetApicTimerInitCount ();
213 if (EndValue
!= NULL
) {
217 return (UINT64
) InternalX86GetTimerFrequency ();
221 Converts elapsed ticks of performance counter to time in nanoseconds.
223 This function converts the elapsed ticks of running performance counter to
224 time value in unit of nanoseconds.
226 @param Ticks The number of elapsed ticks of running performance counter.
228 @return The elapsed time in nanoseconds.
233 GetTimeInNanoSecond (
242 Frequency
= GetPerformanceCounterProperties (NULL
, NULL
);
246 // Time = --------- x 1,000,000,000
249 NanoSeconds
= MultU64x32 (DivU64x64Remainder (Ticks
, Frequency
, &Remainder
), 1000000000u);
252 // Ensure (Remainder * 1,000,000,000) will not overflow 64-bit.
253 // Since 2^29 < 1,000,000,000 = 0x3B9ACA00 < 2^30, Remainder should < 2^(64-30) = 2^34,
254 // i.e. highest bit set in Remainder should <= 33.
256 Shift
= MAX (0, HighBitSet64 (Remainder
) - 33);
257 Remainder
= RShiftU64 (Remainder
, (UINTN
) Shift
);
258 Frequency
= RShiftU64 (Frequency
, (UINTN
) Shift
);
259 NanoSeconds
+= DivU64x64Remainder (MultU64x32 (Remainder
, 1000000000u), Frequency
, NULL
);