2 Timer Library functions built upon local APIC on IA32/x64.
4 Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
5 This program and the accompanying materials
6 are licensed and made available under the terms and conditions of the BSD License
7 which accompanies this distribution. The full text of the license may be found at
8 http://opensource.org/licenses/bsd-license.php.
10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
16 #include <Library/TimerLib.h>
17 #include <Library/BaseLib.h>
18 #include <Library/IoLib.h>
19 #include <Library/PcdLib.h>
20 #include <Library/DebugLib.h>
22 #define APIC_SVR 0x0f0
23 #define APIC_LVTERR 0x370
24 #define APIC_TMICT 0x380
25 #define APIC_TMCCT 0x390
26 #define APIC_TDCR 0x3e0
29 // The following array is used in calculating the frequency of local APIC
30 // timer. Refer to IA-32 developers' manual for more details.
32 GLOBAL_REMOVE_IF_UNREFERENCED
33 CONST UINT8 mTimerLibLocalApicDivisor
[] = {
34 0x02, 0x04, 0x08, 0x10,
35 0x02, 0x04, 0x08, 0x10,
36 0x20, 0x40, 0x80, 0x01,
37 0x20, 0x40, 0x80, 0x01
41 Internal function to retrieve the base address of local APIC.
43 This function will ASSERT if:
44 The local APIC is not globally enabled.
45 The local APIC is not working under XAPIC mode.
46 The local APIC is not software enabled.
48 @return The base address of local APIC
53 InternalX86GetApicBase (
60 MsrValue
= (UINTN
) AsmReadMsr64 (27);
61 ApicBase
= MsrValue
& 0xffffff000ULL
;
64 // Check the APIC Global Enable bit (bit 11) in IA32_APIC_BASE MSR.
65 // This bit will be 1, if local APIC is globally enabled.
67 ASSERT ((MsrValue
& BIT11
) != 0);
70 // Check the APIC Extended Mode bit (bit 10) in IA32_APIC_BASE MSR.
71 // This bit will be 0, if local APIC is under XAPIC mode.
73 ASSERT ((MsrValue
& BIT10
) == 0);
76 // Check the APIC Software Enable/Disable bit (bit 8) in Spurious-Interrupt
78 // This bit will be 1, if local APIC is software enabled.
80 ASSERT ((MmioRead32 (ApicBase
+ APIC_SVR
) & BIT8
) != 0);
86 Internal function to return the frequency of the local APIC timer.
88 @param ApicBase The base address of memory mapped registers of local APIC.
90 @return The frequency of the timer in Hz.
95 InternalX86GetTimerFrequency (
100 PcdGet32(PcdFSBClock
) /
101 mTimerLibLocalApicDivisor
[MmioBitFieldRead32 (ApicBase
+ APIC_TDCR
, 0, 3)];
105 Internal function to read the current tick counter of local APIC.
107 @param ApicBase The base address of memory mapped registers of local APIC.
109 @return The tick counter read.
114 InternalX86GetTimerTick (
118 return MmioRead32 (ApicBase
+ APIC_TMCCT
);
122 Internal function to read the initial timer count of local APIC.
124 @param ApicBase The base address of memory mapped registers of local APIC.
126 @return The initial timer count read.
130 InternalX86GetInitTimerCount (
134 return MmioRead32 (ApicBase
+ APIC_TMICT
);
138 Stalls the CPU for at least the given number of ticks.
140 Stalls the CPU for at least the given number of ticks. It's invoked by
141 MicroSecondDelay() and NanoSecondDelay().
143 This function will ASSERT if the APIC timer intial count returned from
144 InternalX86GetInitTimerCount() is zero.
146 @param ApicBase The base address of memory mapped registers of local APIC.
147 @param Delay A period of time to delay in ticks.
163 // In case Delay is too larger, separate it into several small delay slot.
164 // Devided Delay by half value of Init Count is to avoid Delay close to
165 // the Init Count, timeout maybe missing if the time consuming between 2
166 // GetApicTimerCurrentCount() invoking is larger than the time gap between
167 // Delay and the Init Count.
169 InitCount
= InternalX86GetInitTimerCount (ApicBase
);
170 ASSERT (InitCount
!= 0);
171 Times
= Delay
/ (InitCount
/ 2);
172 Delay
= Delay
% (InitCount
/ 2);
175 // Get Start Tick and do delay
177 StartTick
= InternalX86GetTimerTick (ApicBase
);
180 // Wait until time out by Delay value
185 // Get Ticks from Start to Current.
187 Ticks
= StartTick
- InternalX86GetTimerTick (ApicBase
);
189 // Ticks < 0 means Timer wrap-arounds happens.
194 } while ((UINT32
)Ticks
< Delay
);
197 // Update StartTick and Delay for next delay slot
199 StartTick
-= (StartTick
> Delay
) ? Delay
: (Delay
- InitCount
);
200 Delay
= InitCount
/ 2;
201 } while (Times
-- > 0);
205 Stalls the CPU for at least the given number of microseconds.
207 Stalls the CPU for the number of microseconds specified by MicroSeconds.
209 @param MicroSeconds The minimum number of microseconds to delay.
211 @return The value of MicroSeconds inputted.
217 IN UINTN MicroSeconds
222 ApicBase
= InternalX86GetApicBase ();
227 InternalX86GetTimerFrequency (ApicBase
),
237 Stalls the CPU for at least the given number of nanoseconds.
239 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
241 @param NanoSeconds The minimum number of nanoseconds to delay.
243 @return The value of NanoSeconds inputted.
254 ApicBase
= InternalX86GetApicBase ();
259 InternalX86GetTimerFrequency (ApicBase
),
269 Retrieves the current value of a 64-bit free running performance counter.
271 The counter can either count up by 1 or count down by 1. If the physical
272 performance counter counts by a larger increment, then the counter values
273 must be translated. The properties of the counter can be retrieved from
274 GetPerformanceCounterProperties().
276 @return The current value of the free running performance counter.
281 GetPerformanceCounter (
285 return (UINT64
)(UINT32
)InternalX86GetTimerTick (InternalX86GetApicBase ());
289 Retrieves the 64-bit frequency in Hz and the range of performance counter
292 If StartValue is not NULL, then the value that the performance counter starts
293 with immediately after is it rolls over is returned in StartValue. If
294 EndValue is not NULL, then the value that the performance counter end with
295 immediately before it rolls over is returned in EndValue. The 64-bit
296 frequency of the performance counter in Hz is always returned. If StartValue
297 is less than EndValue, then the performance counter counts up. If StartValue
298 is greater than EndValue, then the performance counter counts down. For
299 example, a 64-bit free running counter that counts up would have a StartValue
300 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
301 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
303 @param StartValue The value the performance counter starts with when it
305 @param EndValue The value that the performance counter ends with before
308 @return The frequency in Hz.
313 GetPerformanceCounterProperties (
314 OUT UINT64
*StartValue
, OPTIONAL
315 OUT UINT64
*EndValue OPTIONAL
320 ApicBase
= InternalX86GetApicBase ();
322 if (StartValue
!= NULL
) {
323 *StartValue
= (UINT64
)InternalX86GetInitTimerCount (ApicBase
);
326 if (EndValue
!= NULL
) {
330 return (UINT64
) InternalX86GetTimerFrequency (ApicBase
);
334 Converts elapsed ticks of performance counter to time in nanoseconds.
336 This function converts the elapsed ticks of running performance counter to
337 time value in unit of nanoseconds.
339 @param Ticks The number of elapsed ticks of running performance counter.
341 @return The elapsed time in nanoseconds.
346 GetTimeInNanoSecond (
355 Frequency
= GetPerformanceCounterProperties (NULL
, NULL
);
359 // Time = --------- x 1,000,000,000
362 NanoSeconds
= MultU64x32 (DivU64x64Remainder (Ticks
, Frequency
, &Remainder
), 1000000000u);
365 // Ensure (Remainder * 1,000,000,000) will not overflow 64-bit.
366 // Since 2^29 < 1,000,000,000 = 0x3B9ACA00 < 2^30, Remainder should < 2^(64-30) = 2^34,
367 // i.e. highest bit set in Remainder should <= 33.
369 Shift
= MAX (0, HighBitSet64 (Remainder
) - 33);
370 Remainder
= RShiftU64 (Remainder
, (UINTN
) Shift
);
371 Frequency
= RShiftU64 (Frequency
, (UINTN
) Shift
);
372 NanoSeconds
+= DivU64x64Remainder (MultU64x32 (Remainder
, 1000000000u), Frequency
, NULL
);