]>
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 - 2015, 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 This function will ASSERT if the APIC timer intial count returned from
49 GetApicTimerInitCount() is zero.
51 @param Delay A period of time to delay in ticks.
66 // In case Delay is too larger, separate it into several small delay slot.
67 // Devided Delay by half value of Init Count is to avoid Delay close to
68 // the Init Count, timeout maybe missing if the time consuming between 2
69 // GetApicTimerCurrentCount() invoking is larger than the time gap between
70 // Delay and the Init Count.
72 InitCount
= GetApicTimerInitCount ();
73 ASSERT (InitCount
!= 0);
74 Times
= Delay
/ (InitCount
/ 2);
75 Delay
= Delay
% (InitCount
/ 2);
78 // Get Start Tick and do delay
80 StartTick
= GetApicTimerCurrentCount ();
83 // Wait until time out by Delay value
88 // Get Ticks from Start to Current.
90 Ticks
= StartTick
- GetApicTimerCurrentCount ();
92 // Ticks < 0 means Timer wrap-arounds happens.
97 } while ((UINT32
)Ticks
< Delay
);
100 // Update StartTick and Delay for next delay slot
102 StartTick
-= (StartTick
> Delay
) ? Delay
: (Delay
- InitCount
);
103 Delay
= InitCount
/ 2;
104 } while (Times
-- > 0);
108 Stalls the CPU for at least the given number of microseconds.
110 Stalls the CPU for the number of microseconds specified by MicroSeconds.
112 @param MicroSeconds The minimum number of microseconds to delay.
114 @return The value of MicroSeconds inputted.
120 IN UINTN MicroSeconds
126 InternalX86GetTimerFrequency (),
136 Stalls the CPU for at least the given number of nanoseconds.
138 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
140 @param NanoSeconds The minimum number of nanoseconds to delay.
142 @return The value of NanoSeconds inputted.
154 InternalX86GetTimerFrequency (),
164 Retrieves the current value of a 64-bit free running performance counter.
166 The counter can either count up by 1 or count down by 1. If the physical
167 performance counter counts by a larger increment, then the counter values
168 must be translated. The properties of the counter can be retrieved from
169 GetPerformanceCounterProperties().
171 @return The current value of the free running performance counter.
176 GetPerformanceCounter (
180 return (UINT64
)GetApicTimerCurrentCount ();
184 Retrieves the 64-bit frequency in Hz and the range of performance counter
187 If StartValue is not NULL, then the value that the performance counter starts
188 with immediately after is it rolls over is returned in StartValue. If
189 EndValue is not NULL, then the value that the performance counter end with
190 immediately before it rolls over is returned in EndValue. The 64-bit
191 frequency of the performance counter in Hz is always returned. If StartValue
192 is less than EndValue, then the performance counter counts up. If StartValue
193 is greater than EndValue, then the performance counter counts down. For
194 example, a 64-bit free running counter that counts up would have a StartValue
195 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
196 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
198 @param StartValue The value the performance counter starts with when it
200 @param EndValue The value that the performance counter ends with before
203 @return The frequency in Hz.
208 GetPerformanceCounterProperties (
209 OUT UINT64
*StartValue
, OPTIONAL
210 OUT UINT64
*EndValue OPTIONAL
213 if (StartValue
!= NULL
) {
214 *StartValue
= (UINT64
)GetApicTimerInitCount ();
217 if (EndValue
!= NULL
) {
221 return (UINT64
) InternalX86GetTimerFrequency ();
225 Converts elapsed ticks of performance counter to time in nanoseconds.
227 This function converts the elapsed ticks of running performance counter to
228 time value in unit of nanoseconds.
230 @param Ticks The number of elapsed ticks of running performance counter.
232 @return The elapsed time in nanoseconds.
237 GetTimeInNanoSecond (
246 Frequency
= GetPerformanceCounterProperties (NULL
, NULL
);
250 // Time = --------- x 1,000,000,000
253 NanoSeconds
= MultU64x32 (DivU64x64Remainder (Ticks
, Frequency
, &Remainder
), 1000000000u);
256 // Ensure (Remainder * 1,000,000,000) will not overflow 64-bit.
257 // Since 2^29 < 1,000,000,000 = 0x3B9ACA00 < 2^30, Remainder should < 2^(64-30) = 2^34,
258 // i.e. highest bit set in Remainder should <= 33.
260 Shift
= MAX (0, HighBitSet64 (Remainder
) - 33);
261 Remainder
= RShiftU64 (Remainder
, (UINTN
) Shift
);
262 Frequency
= RShiftU64 (Frequency
, (UINTN
) Shift
);
263 NanoSeconds
+= DivU64x64Remainder (MultU64x32 (Remainder
, 1000000000u), Frequency
, NULL
);