2 Timer Library functions built upon local APIC on IA32/x64.
4 Copyright (c) 2006 - 2007, Intel Corporation<BR>
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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.
13 Module Name: x86TimerLib.c
18 // The following array is used in calculating the frequency of local APIC
19 // timer. Refer to IA-32 developers' manual for more details.
21 GLOBAL_REMOVE_IF_UNREFERENCED
22 CONST UINT8 mTimerLibLocalApicDivisor
[] = {
23 0x02, 0x04, 0x08, 0x10,
24 0x02, 0x04, 0x08, 0x10,
25 0x20, 0x40, 0x80, 0x01,
26 0x20, 0x40, 0x80, 0x01
30 Internal function to retrieve the base address of local APIC.
32 Internal function to retrieve the base address of local APIC.
34 @return The base address of local APIC
39 InternalX86GetApicBase (
43 return (UINTN
)AsmMsrBitFieldRead64 (27, 12, 35) << 12;
47 Internal function to return the frequency of the local APIC timer.
49 Internal function to return the frequency of the local APIC timer.
51 @param ApicBase The base address of memory mapped registers of local APIC.
53 @return The frequency of the timer in Hz.
58 InternalX86GetTimerFrequency (
63 PcdGet32(PcdFSBClock
) /
64 mTimerLibLocalApicDivisor
[MmioBitFieldRead32 (ApicBase
+ 0x3e0, 0, 3)];
68 Internal function to read the current tick counter of local APIC.
70 Internal function to read the current tick counter of local APIC.
72 @param ApicBase The base address of memory mapped registers of local APIC.
74 @return The tick counter read.
79 InternalX86GetTimerTick (
83 return MmioRead32 (ApicBase
+ 0x390);
87 Stalls the CPU for at least the given number of ticks.
89 Stalls the CPU for at least the given number of ticks. It's invoked by
90 MicroSecondDelay() and NanoSecondDelay().
92 @param ApicBase The base address of memory mapped registers of local APIC.
93 @param Delay A period of time to delay in ticks.
106 // The target timer count is calculated here
108 Ticks
= InternalX86GetTimerTick (ApicBase
) - Delay
;
111 // Wait until time out
112 // Delay > 2^31 could not be handled by this function
113 // Timer wrap-arounds are handled correctly by this function
115 while (InternalX86GetTimerTick (ApicBase
) - Ticks
>= 0);
119 Stalls the CPU for at least the given number of microseconds.
121 Stalls the CPU for the number of microseconds specified by MicroSeconds.
123 @param MicroSeconds The minimum number of microseconds to delay.
131 IN UINTN MicroSeconds
136 ApicBase
= InternalX86GetApicBase ();
141 InternalX86GetTimerFrequency (ApicBase
),
151 Stalls the CPU for at least the given number of nanoseconds.
153 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
155 @param NanoSeconds The minimum number of nanoseconds to delay.
168 ApicBase
= InternalX86GetApicBase ();
173 InternalX86GetTimerFrequency (ApicBase
),
183 Retrieves the current value of a 64-bit free running performance counter.
185 Retrieves the current value of a 64-bit free running performance counter. The
186 counter can either count up by 1 or count down by 1. If the physical
187 performance counter counts by a larger increment, then the counter values
188 must be translated. The properties of the counter can be retrieved from
189 GetPerformanceCounterProperties().
191 @return The current value of the free running performance counter.
196 GetPerformanceCounter (
200 return (UINT64
)(UINT32
)InternalX86GetTimerTick (InternalX86GetApicBase ());
204 Retrieves the 64-bit frequency in Hz and the range of performance counter
207 If StartValue is not NULL, then the value that the performance counter starts
208 with immediately after is it rolls over is returned in StartValue. If
209 EndValue is not NULL, then the value that the performance counter end with
210 immediately before it rolls over is returned in EndValue. The 64-bit
211 frequency of the performance counter in Hz is always returned. If StartValue
212 is less than EndValue, then the performance counter counts up. If StartValue
213 is greater than EndValue, then the performance counter counts down. For
214 example, a 64-bit free running counter that counts up would have a StartValue
215 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
216 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
218 @param StartValue The value the performance counter starts with when it
220 @param EndValue The value that the performance counter ends with before
223 @return The frequency in Hz.
228 GetPerformanceCounterProperties (
229 OUT UINT64
*StartValue
, OPTIONAL
230 OUT UINT64
*EndValue OPTIONAL
235 ApicBase
= InternalX86GetApicBase ();
237 if (StartValue
!= NULL
) {
238 *StartValue
= MmioRead32 (ApicBase
+ 0x380);
241 if (EndValue
!= NULL
) {
245 return (UINT64
) InternalX86GetTimerFrequency (ApicBase
);;