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 <Library/TimerLib.h>
19 #include <Library/BaseLib.h>
20 #include <Library/IoLib.h>
21 #include <Library/DebugLib.h>
22 #include <Library/PcdLib.h>
26 // The following array is used in calculating the frequency of local APIC
27 // timer. Refer to IA-32 developers' manual for more details.
29 GLOBAL_REMOVE_IF_UNREFERENCED
30 CONST UINT8 mTimerLibLocalApicDivisor
[] = {
31 0x02, 0x04, 0x08, 0x10,
32 0x02, 0x04, 0x08, 0x10,
33 0x20, 0x40, 0x80, 0x01,
34 0x20, 0x40, 0x80, 0x01
38 Internal function to retrieve the base address of local APIC.
40 Internal function to retrieve the base address of local APIC.
42 @return The base address of local APIC
47 InternalX86GetApicBase (
51 return (UINTN
)AsmMsrBitFieldRead64 (27, 12, 35) << 12;
55 Internal function to return the frequency of the local APIC timer.
57 Internal function to return the frequency of the local APIC timer.
59 @param ApicBase The base address of memory mapped registers of local APIC.
61 @return The frequency of the timer in Hz.
66 InternalX86GetTimerFrequency (
71 PcdGet32(PcdFSBClock
) /
72 mTimerLibLocalApicDivisor
[MmioBitFieldRead32 (ApicBase
+ 0x3e0, 0, 3)];
76 Internal function to read the current tick counter of local APIC.
78 Internal function to read the current tick counter of local APIC.
80 @param ApicBase The base address of memory mapped registers of local APIC.
82 @return The tick counter read.
87 InternalX86GetTimerTick (
91 return MmioRead32 (ApicBase
+ 0x390);
95 Stalls the CPU for at least the given number of ticks.
97 Stalls the CPU for at least the given number of ticks. It's invoked by
98 MicroSecondDelay() and NanoSecondDelay().
100 @param ApicBase The base address of memory mapped registers of local APIC.
101 @param Delay A period of time to delay in ticks.
114 // The target timer count is calculated here
116 Ticks
= InternalX86GetTimerTick (ApicBase
) - Delay
;
119 // Wait until time out
120 // Delay > 2^31 could not be handled by this function
121 // Timer wrap-arounds are handled correctly by this function
123 while (InternalX86GetTimerTick (ApicBase
) - Ticks
>= 0);
127 Stalls the CPU for at least the given number of microseconds.
129 Stalls the CPU for the number of microseconds specified by MicroSeconds.
131 @param MicroSeconds The minimum number of microseconds to delay.
139 IN UINTN MicroSeconds
144 ApicBase
= InternalX86GetApicBase ();
149 InternalX86GetTimerFrequency (ApicBase
),
159 Stalls the CPU for at least the given number of nanoseconds.
161 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
163 @param NanoSeconds The minimum number of nanoseconds to delay.
176 ApicBase
= InternalX86GetApicBase ();
181 InternalX86GetTimerFrequency (ApicBase
),
191 Retrieves the current value of a 64-bit free running performance counter.
193 Retrieves the current value of a 64-bit free running performance counter. The
194 counter can either count up by 1 or count down by 1. If the physical
195 performance counter counts by a larger increment, then the counter values
196 must be translated. The properties of the counter can be retrieved from
197 GetPerformanceCounterProperties().
199 @return The current value of the free running performance counter.
204 GetPerformanceCounter (
208 return (UINT64
)(UINT32
)InternalX86GetTimerTick (InternalX86GetApicBase ());
212 Retrieves the 64-bit frequency in Hz and the range of performance counter
215 If StartValue is not NULL, then the value that the performance counter starts
216 with immediately after is it rolls over is returned in StartValue. If
217 EndValue is not NULL, then the value that the performance counter end with
218 immediately before it rolls over is returned in EndValue. The 64-bit
219 frequency of the performance counter in Hz is always returned. If StartValue
220 is less than EndValue, then the performance counter counts up. If StartValue
221 is greater than EndValue, then the performance counter counts down. For
222 example, a 64-bit free running counter that counts up would have a StartValue
223 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
224 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
226 @param StartValue The value the performance counter starts with when it
228 @param EndValue The value that the performance counter ends with before
231 @return The frequency in Hz.
236 GetPerformanceCounterProperties (
237 OUT UINT64
*StartValue
, OPTIONAL
238 OUT UINT64
*EndValue OPTIONAL
243 ApicBase
= InternalX86GetApicBase ();
245 if (StartValue
!= NULL
) {
246 *StartValue
= MmioRead32 (ApicBase
+ 0x380);
249 if (EndValue
!= NULL
) {
253 return (UINT64
) InternalX86GetTimerFrequency (ApicBase
);;