1 /** @file
2 Timer Library functions built upon local APIC on IA32/x64.
3
4 Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
5 SPDX-License-Identifier: BSD-2-Clause-Patent
6
7 **/
8
9 #include <Base.h>
10 #include <Library/TimerLib.h>
11 #include <Library/BaseLib.h>
12 #include <Library/IoLib.h>
13 #include <Library/PcdLib.h>
14 #include <Library/DebugLib.h>
15
16 #define APIC_SVR 0x0f0
17 #define APIC_LVTERR 0x370
18 #define APIC_TMICT 0x380
19 #define APIC_TMCCT 0x390
20 #define APIC_TDCR 0x3e0
21
22 //
23 // The following array is used in calculating the frequency of local APIC
24 // timer. Refer to IA-32 developers' manual for more details.
25 //
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
32 };
33
34 /**
35 Internal function to retrieve the base address of local APIC.
36
37 This function will ASSERT if:
38 The local APIC is not globally enabled.
39 The local APIC is not working under XAPIC mode.
40 The local APIC is not software enabled.
41
42 @return The base address of local APIC
43
44 **/
45 UINTN
46 EFIAPI
InternalX86GetApicBase(VOID)47 InternalX86GetApicBase (
48 VOID
49 )
50 {
51 UINTN MsrValue;
52 UINTN ApicBase;
53
54 MsrValue = (UINTN) AsmReadMsr64 (27);
55 ApicBase = MsrValue & 0xffffff000ULL;
56
57 //
58 // Check the APIC Global Enable bit (bit 11) in IA32_APIC_BASE MSR.
59 // This bit will be 1, if local APIC is globally enabled.
60 //
61 ASSERT ((MsrValue & BIT11) != 0);
62
63 //
64 // Check the APIC Extended Mode bit (bit 10) in IA32_APIC_BASE MSR.
65 // This bit will be 0, if local APIC is under XAPIC mode.
66 //
67 ASSERT ((MsrValue & BIT10) == 0);
68
69 //
70 // Check the APIC Software Enable/Disable bit (bit 8) in Spurious-Interrupt
71 // Vector Register.
72 // This bit will be 1, if local APIC is software enabled.
73 //
74 ASSERT ((MmioRead32 (ApicBase + APIC_SVR) & BIT8) != 0);
75
76 return ApicBase;
77 }
78
79 /**
80 Internal function to return the frequency of the local APIC timer.
81
82 @param ApicBase The base address of memory mapped registers of local APIC.
83
84 @return The frequency of the timer in Hz.
85
86 **/
87 UINT32
88 EFIAPI
InternalX86GetTimerFrequency(IN UINTN ApicBase)89 InternalX86GetTimerFrequency (
90 IN UINTN ApicBase
91 )
92 {
93 return
94 PcdGet32(PcdFSBClock) /
95 mTimerLibLocalApicDivisor[MmioBitFieldRead32 (ApicBase + APIC_TDCR, 0, 3)];
96 }
97
98 /**
99 Internal function to read the current tick counter of local APIC.
100
101 @param ApicBase The base address of memory mapped registers of local APIC.
102
103 @return The tick counter read.
104
105 **/
106 INT32
107 EFIAPI
InternalX86GetTimerTick(IN UINTN ApicBase)108 InternalX86GetTimerTick (
109 IN UINTN ApicBase
110 )
111 {
112 return MmioRead32 (ApicBase + APIC_TMCCT);
113 }
114
115 /**
116 Internal function to read the initial timer count of local APIC.
117
118 @param ApicBase The base address of memory mapped registers of local APIC.
119
120 @return The initial timer count read.
121
122 **/
123 UINT32
InternalX86GetInitTimerCount(IN UINTN ApicBase)124 InternalX86GetInitTimerCount (
125 IN UINTN ApicBase
126 )
127 {
128 return MmioRead32 (ApicBase + APIC_TMICT);
129 }
130
131 /**
132 Stalls the CPU for at least the given number of ticks.
133
134 Stalls the CPU for at least the given number of ticks. It's invoked by
135 MicroSecondDelay() and NanoSecondDelay().
136
137 This function will ASSERT if the APIC timer intial count returned from
138 InternalX86GetInitTimerCount() is zero.
139
140 @param ApicBase The base address of memory mapped registers of local APIC.
141 @param Delay A period of time to delay in ticks.
142
143 **/
144 VOID
145 EFIAPI
InternalX86Delay(IN UINTN ApicBase,IN UINT32 Delay)146 InternalX86Delay (
147 IN UINTN ApicBase,
148 IN UINT32 Delay
149 )
150 {
151 INT32 Ticks;
152 UINT32 Times;
153 UINT32 InitCount;
154 UINT32 StartTick;
155
156 //
157 // In case Delay is too larger, separate it into several small delay slot.
158 // Devided Delay by half value of Init Count is to avoid Delay close to
159 // the Init Count, timeout maybe missing if the time consuming between 2
160 // GetApicTimerCurrentCount() invoking is larger than the time gap between
161 // Delay and the Init Count.
162 //
163 InitCount = InternalX86GetInitTimerCount (ApicBase);
164 ASSERT (InitCount != 0);
165 Times = Delay / (InitCount / 2);
166 Delay = Delay % (InitCount / 2);
167
168 //
169 // Get Start Tick and do delay
170 //
171 StartTick = InternalX86GetTimerTick (ApicBase);
172 do {
173 //
174 // Wait until time out by Delay value
175 //
176 do {
177 CpuPause ();
178 //
179 // Get Ticks from Start to Current.
180 //
181 Ticks = StartTick - InternalX86GetTimerTick (ApicBase);
182 //
183 // Ticks < 0 means Timer wrap-arounds happens.
184 //
185 if (Ticks < 0) {
186 Ticks += InitCount;
187 }
188 } while ((UINT32)Ticks < Delay);
189
190 //
191 // Update StartTick and Delay for next delay slot
192 //
193 StartTick -= (StartTick > Delay) ? Delay : (Delay - InitCount);
194 Delay = InitCount / 2;
195 } while (Times-- > 0);
196 }
197
198 /**
199 Stalls the CPU for at least the given number of microseconds.
200
201 Stalls the CPU for the number of microseconds specified by MicroSeconds.
202
203 @param MicroSeconds The minimum number of microseconds to delay.
204
205 @return The value of MicroSeconds inputted.
206
207 **/
208 UINTN
209 EFIAPI
MicroSecondDelay(IN UINTN MicroSeconds)210 MicroSecondDelay (
211 IN UINTN MicroSeconds
212 )
213 {
214 UINTN ApicBase;
215
216 ApicBase = InternalX86GetApicBase ();
217 InternalX86Delay (
218 ApicBase,
219 (UINT32)DivU64x32 (
220 MultU64x64 (
221 InternalX86GetTimerFrequency (ApicBase),
222 MicroSeconds
223 ),
224 1000000u
225 )
226 );
227 return MicroSeconds;
228 }
229
230 /**
231 Stalls the CPU for at least the given number of nanoseconds.
232
233 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
234
235 @param NanoSeconds The minimum number of nanoseconds to delay.
236
237 @return The value of NanoSeconds inputted.
238
239 **/
240 UINTN
241 EFIAPI
NanoSecondDelay(IN UINTN NanoSeconds)242 NanoSecondDelay (
243 IN UINTN NanoSeconds
244 )
245 {
246 UINTN ApicBase;
247
248 ApicBase = InternalX86GetApicBase ();
249 InternalX86Delay (
250 ApicBase,
251 (UINT32)DivU64x32 (
252 MultU64x64 (
253 InternalX86GetTimerFrequency (ApicBase),
254 NanoSeconds
255 ),
256 1000000000u
257 )
258 );
259 return NanoSeconds;
260 }
261
262 /**
263 Retrieves the current value of a 64-bit free running performance counter.
264
265 The counter can either count up by 1 or count down by 1. If the physical
266 performance counter counts by a larger increment, then the counter values
267 must be translated. The properties of the counter can be retrieved from
268 GetPerformanceCounterProperties().
269
270 @return The current value of the free running performance counter.
271
272 **/
273 UINT64
274 EFIAPI
GetPerformanceCounter(VOID)275 GetPerformanceCounter (
276 VOID
277 )
278 {
279 return (UINT64)(UINT32)InternalX86GetTimerTick (InternalX86GetApicBase ());
280 }
281
282 /**
283 Retrieves the 64-bit frequency in Hz and the range of performance counter
284 values.
285
286 If StartValue is not NULL, then the value that the performance counter starts
287 with immediately after is it rolls over is returned in StartValue. If
288 EndValue is not NULL, then the value that the performance counter end with
289 immediately before it rolls over is returned in EndValue. The 64-bit
290 frequency of the performance counter in Hz is always returned. If StartValue
291 is less than EndValue, then the performance counter counts up. If StartValue
292 is greater than EndValue, then the performance counter counts down. For
293 example, a 64-bit free running counter that counts up would have a StartValue
294 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
295 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
296
297 @param StartValue The value the performance counter starts with when it
298 rolls over.
299 @param EndValue The value that the performance counter ends with before
300 it rolls over.
301
302 @return The frequency in Hz.
303
304 **/
305 UINT64
306 EFIAPI
GetPerformanceCounterProperties(OUT UINT64 * StartValue,OPTIONAL OUT UINT64 * EndValue OPTIONAL)307 GetPerformanceCounterProperties (
308 OUT UINT64 *StartValue, OPTIONAL
309 OUT UINT64 *EndValue OPTIONAL
310 )
311 {
312 UINTN ApicBase;
313
314 ApicBase = InternalX86GetApicBase ();
315
316 if (StartValue != NULL) {
317 *StartValue = (UINT64)InternalX86GetInitTimerCount (ApicBase);
318 }
319
320 if (EndValue != NULL) {
321 *EndValue = 0;
322 }
323
324 return (UINT64) InternalX86GetTimerFrequency (ApicBase);
325 }
326
327 /**
328 Converts elapsed ticks of performance counter to time in nanoseconds.
329
330 This function converts the elapsed ticks of running performance counter to
331 time value in unit of nanoseconds.
332
333 @param Ticks The number of elapsed ticks of running performance counter.
334
335 @return The elapsed time in nanoseconds.
336
337 **/
338 UINT64
339 EFIAPI
GetTimeInNanoSecond(IN UINT64 Ticks)340 GetTimeInNanoSecond (
341 IN UINT64 Ticks
342 )
343 {
344 UINT64 Frequency;
345 UINT64 NanoSeconds;
346 UINT64 Remainder;
347 INTN Shift;
348
349 Frequency = GetPerformanceCounterProperties (NULL, NULL);
350
351 //
352 // Ticks
353 // Time = --------- x 1,000,000,000
354 // Frequency
355 //
356 NanoSeconds = MultU64x32 (DivU64x64Remainder (Ticks, Frequency, &Remainder), 1000000000u);
357
358 //
359 // Ensure (Remainder * 1,000,000,000) will not overflow 64-bit.
360 // Since 2^29 < 1,000,000,000 = 0x3B9ACA00 < 2^30, Remainder should < 2^(64-30) = 2^34,
361 // i.e. highest bit set in Remainder should <= 33.
362 //
363 Shift = MAX (0, HighBitSet64 (Remainder) - 33);
364 Remainder = RShiftU64 (Remainder, (UINTN) Shift);
365 Frequency = RShiftU64 (Frequency, (UINTN) Shift);
366 NanoSeconds += DivU64x64Remainder (MultU64x32 (Remainder, 1000000000u), Frequency, NULL);
367
368 return NanoSeconds;
369 }
370