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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 - 2018, Intel Corporation. All rights reserved.<BR>
7 SPDX-License-Identifier: BSD-2-Clause-Patent
12 #include <Library/TimerLib.h>
13 #include <Library/BaseLib.h>
14 #include <Library/PcdLib.h>
15 #include <Library/DebugLib.h>
16 #include <Library/LocalApicLib.h>
19 Internal function to return the frequency of the local APIC timer.
21 @return The frequency of the timer in Hz.
26 InternalX86GetTimerFrequency (
32 GetApicTimerState (&Divisor
, NULL
, NULL
);
33 return PcdGet32(PcdFSBClock
) / (UINT32
)Divisor
;
37 Stalls the CPU for at least the given number of ticks.
39 Stalls the CPU for at least the given number of ticks. It's invoked by
40 MicroSecondDelay() and NanoSecondDelay().
42 This function will ASSERT if the APIC timer intial count returned from
43 GetApicTimerInitCount() is zero.
45 @param Delay A period of time to delay in ticks.
60 // In case Delay is too larger, separate it into several small delay slot.
61 // Devided Delay by half value of Init Count is to avoid Delay close to
62 // the Init Count, timeout maybe missing if the time consuming between 2
63 // GetApicTimerCurrentCount() invoking is larger than the time gap between
64 // Delay and the Init Count.
66 InitCount
= GetApicTimerInitCount ();
67 ASSERT (InitCount
!= 0);
68 Times
= Delay
/ (InitCount
/ 2);
69 Delay
= Delay
% (InitCount
/ 2);
72 // Get Start Tick and do delay
74 StartTick
= GetApicTimerCurrentCount ();
77 // Wait until time out by Delay value
82 // Get Ticks from Start to Current.
84 Ticks
= StartTick
- GetApicTimerCurrentCount ();
86 // Ticks < 0 means Timer wrap-arounds happens.
91 } while ((UINT32
)Ticks
< Delay
);
94 // Update StartTick and Delay for next delay slot
96 StartTick
-= (StartTick
> Delay
) ? Delay
: (Delay
- InitCount
);
97 Delay
= InitCount
/ 2;
98 } while (Times
-- > 0);
102 Stalls the CPU for at least the given number of microseconds.
104 Stalls the CPU for the number of microseconds specified by MicroSeconds.
106 @param MicroSeconds The minimum number of microseconds to delay.
108 @return The value of MicroSeconds inputted.
114 IN UINTN MicroSeconds
120 InternalX86GetTimerFrequency (),
130 Stalls the CPU for at least the given number of nanoseconds.
132 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
134 @param NanoSeconds The minimum number of nanoseconds to delay.
136 @return The value of NanoSeconds inputted.
148 InternalX86GetTimerFrequency (),
158 Retrieves the current value of a 64-bit free running performance counter.
160 The counter can either count up by 1 or count down by 1. If the physical
161 performance counter counts by a larger increment, then the counter values
162 must be translated. The properties of the counter can be retrieved from
163 GetPerformanceCounterProperties().
165 @return The current value of the free running performance counter.
170 GetPerformanceCounter (
174 return (UINT64
)GetApicTimerCurrentCount ();
178 Retrieves the 64-bit frequency in Hz and the range of performance counter
181 If StartValue is not NULL, then the value that the performance counter starts
182 with immediately after is it rolls over is returned in StartValue. If
183 EndValue is not NULL, then the value that the performance counter end with
184 immediately before it rolls over is returned in EndValue. The 64-bit
185 frequency of the performance counter in Hz is always returned. If StartValue
186 is less than EndValue, then the performance counter counts up. If StartValue
187 is greater than EndValue, then the performance counter counts down. For
188 example, a 64-bit free running counter that counts up would have a StartValue
189 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
190 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
192 @param StartValue The value the performance counter starts with when it
194 @param EndValue The value that the performance counter ends with before
197 @return The frequency in Hz.
202 GetPerformanceCounterProperties (
203 OUT UINT64
*StartValue
, OPTIONAL
204 OUT UINT64
*EndValue OPTIONAL
207 if (StartValue
!= NULL
) {
208 *StartValue
= (UINT64
)GetApicTimerInitCount ();
211 if (EndValue
!= NULL
) {
215 return (UINT64
) InternalX86GetTimerFrequency ();
219 Converts elapsed ticks of performance counter to time in nanoseconds.
221 This function converts the elapsed ticks of running performance counter to
222 time value in unit of nanoseconds.
224 @param Ticks The number of elapsed ticks of running performance counter.
226 @return The elapsed time in nanoseconds.
231 GetTimeInNanoSecond (
240 Frequency
= GetPerformanceCounterProperties (NULL
, NULL
);
244 // Time = --------- x 1,000,000,000
247 NanoSeconds
= MultU64x32 (DivU64x64Remainder (Ticks
, Frequency
, &Remainder
), 1000000000u);
250 // Ensure (Remainder * 1,000,000,000) will not overflow 64-bit.
251 // Since 2^29 < 1,000,000,000 = 0x3B9ACA00 < 2^30, Remainder should < 2^(64-30) = 2^34,
252 // i.e. highest bit set in Remainder should <= 33.
254 Shift
= MAX (0, HighBitSet64 (Remainder
) - 33);
255 Remainder
= RShiftU64 (Remainder
, (UINTN
) Shift
);
256 Frequency
= RShiftU64 (Frequency
, (UINTN
) Shift
);
257 NanoSeconds
+= DivU64x64Remainder (MultU64x32 (Remainder
, 1000000000u), Frequency
, NULL
);