2 Timer Library functions built upon local APIC on IA32/x64.
4 Copyright (c) 2006 - 2008, Intel Corporation<BR>
5 All rights reserved. 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>
23 // The following array is used in calculating the frequency of local APIC
24 // timer. Refer to IA-32 developers' manual for more details.
26 GLOBAL_REMOVE_IF_UNREFERENCED
27 CONST UINT8 mTimerLibLocalApicDivisor
[] = {
28 0x02, 0x04, 0x08, 0x10,
29 0x02, 0x04, 0x08, 0x10,
30 0x20, 0x40, 0x80, 0x01,
31 0x20, 0x40, 0x80, 0x01
35 Internal function to retrieve the base address of local APIC.
37 @return The base address of local APIC
42 InternalX86GetApicBase (
46 return (UINTN
)AsmMsrBitFieldRead64 (27, 12, 35) << 12;
50 Internal function to return the frequency of the local APIC timer.
52 @param ApicBase The base address of memory mapped registers of local APIC.
54 @return The frequency of the timer in Hz.
59 InternalX86GetTimerFrequency (
64 PcdGet32(PcdFSBClock
) /
65 mTimerLibLocalApicDivisor
[MmioBitFieldRead32 (ApicBase
+ 0x3e0, 0, 3)];
69 Internal function to read the current tick counter of local APIC.
71 @param ApicBase The base address of memory mapped registers of local APIC.
73 @return The tick counter read.
78 InternalX86GetTimerTick (
82 return MmioRead32 (ApicBase
+ 0x390);
86 Stalls the CPU for at least the given number of ticks.
88 Stalls the CPU for at least the given number of ticks. It's invoked by
89 MicroSecondDelay() and NanoSecondDelay().
91 @param ApicBase The base address of memory mapped registers of local APIC.
92 @param Delay A period of time to delay in ticks.
105 // The target timer count is calculated here
107 Ticks
= InternalX86GetTimerTick (ApicBase
) - Delay
;
110 // Wait until time out
111 // Delay > 2^31 could not be handled by this function
112 // Timer wrap-arounds are handled correctly by this function
114 while (InternalX86GetTimerTick (ApicBase
) - Ticks
>= 0);
118 Stalls the CPU for at least the given number of microseconds.
120 Stalls the CPU for the number of microseconds specified by MicroSeconds.
122 @param MicroSeconds The minimum number of microseconds to delay.
124 @return The value of MicroSeconds inputted.
130 IN UINTN MicroSeconds
135 ApicBase
= InternalX86GetApicBase ();
140 InternalX86GetTimerFrequency (ApicBase
),
150 Stalls the CPU for at least the given number of nanoseconds.
152 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
154 @param NanoSeconds The minimum number of nanoseconds to delay.
156 @return The value of NanoSeconds inputted.
167 ApicBase
= InternalX86GetApicBase ();
172 InternalX86GetTimerFrequency (ApicBase
),
182 Retrieves the current value of a 64-bit free running performance counter. The
183 counter can either count up by 1 or count down by 1. If the physical
184 performance counter counts by a larger increment, then the counter values
185 must be translated. The properties of the counter can be retrieved from
186 GetPerformanceCounterProperties().
188 @return The current value of the free running performance counter.
193 GetPerformanceCounter (
197 return (UINT64
)(UINT32
)InternalX86GetTimerTick (InternalX86GetApicBase ());
201 Retrieves the 64-bit frequency in Hz and the range of performance counter
204 If StartValue is not NULL, then the value that the performance counter starts
205 with immediately after is it rolls over is returned in StartValue. If
206 EndValue is not NULL, then the value that the performance counter end with
207 immediately before it rolls over is returned in EndValue. The 64-bit
208 frequency of the performance counter in Hz is always returned. If StartValue
209 is less than EndValue, then the performance counter counts up. If StartValue
210 is greater than EndValue, then the performance counter counts down. For
211 example, a 64-bit free running counter that counts up would have a StartValue
212 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
213 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
215 @param StartValue The value the performance counter starts with when it
217 @param EndValue The value that the performance counter ends with before
220 @return The frequency in Hz.
225 GetPerformanceCounterProperties (
226 OUT UINT64
*StartValue
, OPTIONAL
227 OUT UINT64
*EndValue OPTIONAL
232 ApicBase
= InternalX86GetApicBase ();
234 if (StartValue
!= NULL
) {
235 *StartValue
= MmioRead32 (ApicBase
+ 0x380);
238 if (EndValue
!= NULL
) {
242 return (UINT64
) InternalX86GetTimerFrequency (ApicBase
);;