2 Timer Library functions built upon local APIC on IA32/x64.
4 Copyright (c) 2006 - 2007, 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.
13 Module Name: x86TimerLib.c
18 // Include common header file for this module.
20 #include "CommonHeader.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 Internal function to retrieve the base address of local APIC.
39 @return The base address of local APIC
44 InternalX86GetApicBase (
48 return (UINTN
)AsmMsrBitFieldRead64 (27, 12, 35) << 12;
52 Internal function to return the frequency of the local APIC timer.
54 Internal function to return the frequency of the local APIC timer.
56 @param ApicBase The base address of memory mapped registers of local APIC.
58 @return The frequency of the timer in Hz.
63 InternalX86GetTimerFrequency (
68 PcdGet32(PcdFSBClock
) /
69 mTimerLibLocalApicDivisor
[MmioBitFieldRead32 (ApicBase
+ 0x3e0, 0, 3)];
73 Internal function to read the current tick counter of local APIC.
75 Internal function to read the current tick counter of local APIC.
77 @param ApicBase The base address of memory mapped registers of local APIC.
79 @return The tick counter read.
84 InternalX86GetTimerTick (
88 return MmioRead32 (ApicBase
+ 0x390);
92 Stalls the CPU for at least the given number of ticks.
94 Stalls the CPU for at least the given number of ticks. It's invoked by
95 MicroSecondDelay() and NanoSecondDelay().
97 @param ApicBase The base address of memory mapped registers of local APIC.
98 @param Delay A period of time to delay in ticks.
111 // The target timer count is calculated here
113 Ticks
= InternalX86GetTimerTick (ApicBase
) - Delay
;
116 // Wait until time out
117 // Delay > 2^31 could not be handled by this function
118 // Timer wrap-arounds are handled correctly by this function
120 while (InternalX86GetTimerTick (ApicBase
) - Ticks
>= 0);
124 Stalls the CPU for at least the given number of microseconds.
126 Stalls the CPU for the number of microseconds specified by MicroSeconds.
128 @param MicroSeconds The minimum number of microseconds to delay.
136 IN UINTN MicroSeconds
141 ApicBase
= InternalX86GetApicBase ();
146 InternalX86GetTimerFrequency (ApicBase
),
156 Stalls the CPU for at least the given number of nanoseconds.
158 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
160 @param NanoSeconds The minimum number of nanoseconds to delay.
173 ApicBase
= InternalX86GetApicBase ();
178 InternalX86GetTimerFrequency (ApicBase
),
188 Retrieves the current value of a 64-bit free running performance counter.
190 Retrieves the current value of a 64-bit free running performance counter. The
191 counter can either count up by 1 or count down by 1. If the physical
192 performance counter counts by a larger increment, then the counter values
193 must be translated. The properties of the counter can be retrieved from
194 GetPerformanceCounterProperties().
196 @return The current value of the free running performance counter.
201 GetPerformanceCounter (
205 return (UINT64
)(UINT32
)InternalX86GetTimerTick (InternalX86GetApicBase ());
209 Retrieves the 64-bit frequency in Hz and the range of performance counter
212 If StartValue is not NULL, then the value that the performance counter starts
213 with immediately after is it rolls over is returned in StartValue. If
214 EndValue is not NULL, then the value that the performance counter end with
215 immediately before it rolls over is returned in EndValue. The 64-bit
216 frequency of the performance counter in Hz is always returned. If StartValue
217 is less than EndValue, then the performance counter counts up. If StartValue
218 is greater than EndValue, then the performance counter counts down. For
219 example, a 64-bit free running counter that counts up would have a StartValue
220 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
221 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
223 @param StartValue The value the performance counter starts with when it
225 @param EndValue The value that the performance counter ends with before
228 @return The frequency in Hz.
233 GetPerformanceCounterProperties (
234 OUT UINT64
*StartValue
, OPTIONAL
235 OUT UINT64
*EndValue OPTIONAL
240 ApicBase
= InternalX86GetApicBase ();
242 if (StartValue
!= NULL
) {
243 *StartValue
= MmioRead32 (ApicBase
+ 0x380);
246 if (EndValue
!= NULL
) {
250 return (UINT64
) InternalX86GetTimerFrequency (ApicBase
);;