2 ACPI Timer implements one instance of Timer Library.
4 Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
5 SPDX-License-Identifier: BSD-2-Clause-Patent
10 #include <Library/TimerLib.h>
11 #include <Library/BaseLib.h>
12 #include <Library/PcdLib.h>
13 #include <Library/PciLib.h>
14 #include <Library/IoLib.h>
15 #include <Library/DebugLib.h>
16 #include <IndustryStandard/Acpi.h>
18 GUID mFrequencyHobGuid
= {
19 0x3fca54f6, 0xe1a2, 0x4b20, { 0xbe, 0x76, 0x92, 0x6b, 0x4b, 0x48, 0xbf, 0xaa }
23 Internal function to retrieves the 64-bit frequency in Hz.
25 Internal function to retrieves the 64-bit frequency in Hz.
27 @return The frequency in Hz.
31 InternalGetPerformanceCounterFrequency (
36 The constructor function enables ACPI IO space.
38 If ACPI I/O space not enabled, this function will enable it.
39 It will always return RETURN_SUCCESS.
41 @retval EFI_SUCCESS The constructor always returns RETURN_SUCCESS.
46 AcpiTimerLibConstructor (
57 // ASSERT for the invalid PCD values. They must be configured to the real value.
59 ASSERT (PcdGet16 (PcdAcpiIoPciBarRegisterOffset
) != 0xFFFF);
60 ASSERT (PcdGet16 (PcdAcpiIoPortBaseAddress
) != 0xFFFF);
63 // If the register offset to the BAR for the ACPI I/O Port Base Address is 0x0000, then
64 // no PCI register programming is required to enable access to the ACPI registers
65 // specified by PcdAcpiIoPortBaseAddress
67 if (PcdGet16 (PcdAcpiIoPciBarRegisterOffset
) == 0x0000) {
68 return RETURN_SUCCESS
;
72 // ASSERT for the invalid PCD values. They must be configured to the real value.
74 ASSERT (PcdGet8 (PcdAcpiIoPciDeviceNumber
) != 0xFF);
75 ASSERT (PcdGet8 (PcdAcpiIoPciFunctionNumber
) != 0xFF);
76 ASSERT (PcdGet16 (PcdAcpiIoPciEnableRegisterOffset
) != 0xFFFF);
79 // Retrieve the PCD values for the PCI configuration space required to program the ACPI I/O Port Base Address
81 Bus
= PcdGet8 (PcdAcpiIoPciBusNumber
);
82 Device
= PcdGet8 (PcdAcpiIoPciDeviceNumber
);
83 Function
= PcdGet8 (PcdAcpiIoPciFunctionNumber
);
84 EnableRegister
= PcdGet16 (PcdAcpiIoPciEnableRegisterOffset
);
85 EnableMask
= PcdGet8 (PcdAcpiIoBarEnableMask
);
88 // If ACPI I/O space is not enabled yet, program ACPI I/O base address and enable it.
90 if ((PciRead8 (PCI_LIB_ADDRESS (Bus
, Device
, Function
, EnableRegister
)) & EnableMask
) != EnableMask
) {
92 PCI_LIB_ADDRESS (Bus
, Device
, Function
, PcdGet16 (PcdAcpiIoPciBarRegisterOffset
)),
93 PcdGet16 (PcdAcpiIoPortBaseAddress
)
96 PCI_LIB_ADDRESS (Bus
, Device
, Function
, EnableRegister
),
101 return RETURN_SUCCESS
;
105 Internal function to retrieve the ACPI I/O Port Base Address.
107 Internal function to retrieve the ACPI I/O Port Base Address.
109 @return The 16-bit ACPI I/O Port Base Address.
113 InternalAcpiGetAcpiTimerIoPort (
119 Port
= PcdGet16 (PcdAcpiIoPortBaseAddress
);
122 // If the register offset to the BAR for the ACPI I/O Port Base Address is not 0x0000, then
123 // read the PCI register for the ACPI BAR value in case the BAR has been programmed to a
124 // value other than PcdAcpiIoPortBaseAddress
126 if (PcdGet16 (PcdAcpiIoPciBarRegisterOffset
) != 0x0000) {
129 PcdGet8 (PcdAcpiIoPciBusNumber
),
130 PcdGet8 (PcdAcpiIoPciDeviceNumber
),
131 PcdGet8 (PcdAcpiIoPciFunctionNumber
),
132 PcdGet16 (PcdAcpiIoPciBarRegisterOffset
)
137 return (Port
& PcdGet16 (PcdAcpiIoPortBaseAddressMask
)) + PcdGet16 (PcdAcpiPm1TmrOffset
);
141 Stalls the CPU for at least the given number of ticks.
143 Stalls the CPU for at least the given number of ticks. It's invoked by
144 MicroSecondDelay() and NanoSecondDelay().
146 @param Delay A period of time to delay in ticks.
158 Port
= InternalAcpiGetAcpiTimerIoPort ();
163 // The target timer count is calculated here
165 Ticks
= IoBitFieldRead32 (Port
, 0, 23) + Delay
;
168 // Wait until time out
169 // Delay >= 2^23 could not be handled by this function
170 // Timer wrap-arounds are handled correctly by this function
172 while (((Ticks
- IoBitFieldRead32 (Port
, 0, 23)) & BIT23
) == 0) {
175 } while (Times
-- > 0);
179 Stalls the CPU for at least the given number of microseconds.
181 Stalls the CPU for the number of microseconds specified by MicroSeconds.
183 @param MicroSeconds The minimum number of microseconds to delay.
191 IN UINTN MicroSeconds
207 Stalls the CPU for at least the given number of nanoseconds.
209 Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
211 @param NanoSeconds The minimum number of nanoseconds to delay.
235 Retrieves the current value of a 64-bit free running performance counter.
237 Retrieves the current value of a 64-bit free running performance counter. The
238 counter can either count up by 1 or count down by 1. If the physical
239 performance counter counts by a larger increment, then the counter values
240 must be translated. The properties of the counter can be retrieved from
241 GetPerformanceCounterProperties().
243 @return The current value of the free running performance counter.
248 GetPerformanceCounter (
252 return AsmReadTsc ();
256 Retrieves the 64-bit frequency in Hz and the range of performance counter
259 If StartValue is not NULL, then the value that the performance counter starts
260 with immediately after is it rolls over is returned in StartValue. If
261 EndValue is not NULL, then the value that the performance counter end with
262 immediately before it rolls over is returned in EndValue. The 64-bit
263 frequency of the performance counter in Hz is always returned. If StartValue
264 is less than EndValue, then the performance counter counts up. If StartValue
265 is greater than EndValue, then the performance counter counts down. For
266 example, a 64-bit free running counter that counts up would have a StartValue
267 of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
268 that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
270 @param StartValue The value the performance counter starts with when it
272 @param EndValue The value that the performance counter ends with before
275 @return The frequency in Hz.
280 GetPerformanceCounterProperties (
281 OUT UINT64
*StartValue OPTIONAL
,
282 OUT UINT64
*EndValue OPTIONAL
285 if (StartValue
!= NULL
) {
289 if (EndValue
!= NULL
) {
290 *EndValue
= 0xffffffffffffffffULL
;
293 return InternalGetPerformanceCounterFrequency ();
297 Converts elapsed ticks of performance counter to time in nanoseconds.
299 This function converts the elapsed ticks of running performance counter to
300 time value in unit of nanoseconds.
302 @param Ticks The number of elapsed ticks of running performance counter.
304 @return The elapsed time in nanoseconds.
309 GetTimeInNanoSecond (
318 Frequency
= GetPerformanceCounterProperties (NULL
, NULL
);
322 // Time = --------- x 1,000,000,000
325 NanoSeconds
= MultU64x32 (DivU64x64Remainder (Ticks
, Frequency
, &Remainder
), 1000000000u);
328 // Ensure (Remainder * 1,000,000,000) will not overflow 64-bit.
329 // Since 2^29 < 1,000,000,000 = 0x3B9ACA00 < 2^30, Remainder should < 2^(64-30) = 2^34,
330 // i.e. highest bit set in Remainder should <= 33.
332 Shift
= MAX (0, HighBitSet64 (Remainder
) - 33);
333 Remainder
= RShiftU64 (Remainder
, (UINTN
)Shift
);
334 Frequency
= RShiftU64 (Frequency
, (UINTN
)Shift
);
335 NanoSeconds
+= DivU64x64Remainder (MultU64x32 (Remainder
, 1000000000u), Frequency
, NULL
);
341 Calculate TSC frequency.
343 The TSC counting frequency is determined by comparing how far it counts
344 during a 101.4 us period as determined by the ACPI timer.
345 The ACPI timer is used because it counts at a known frequency.
346 The TSC is sampled, followed by waiting 363 counts of the ACPI timer,
347 or 101.4 us. The TSC is then sampled again. The difference multiplied by
348 9861 is the TSC frequency. There will be a small error because of the
349 overhead of reading the ACPI timer. An attempt is made to determine and
350 compensate for this error.
352 @return The number of TSC counts per second.
356 InternalCalculateTscFrequency (
365 BOOLEAN InterruptState
;
367 InterruptState
= SaveAndDisableInterrupts ();
369 TimerAddr
= InternalAcpiGetAcpiTimerIoPort ();
371 // Compute the number of ticks to wait to measure TSC frequency.
372 // Use 363 * 9861 = 3579543 Hz which is within 2 Hz of ACPI_TIMER_FREQUENCY.
373 // 363 counts is a calibration time of 101.4 uS.
375 Ticks
= IoBitFieldRead32 (TimerAddr
, 0, 23) + 363;
377 StartTSC
= AsmReadTsc (); // Get base value for the TSC
379 // Wait until the ACPI timer has counted 101.4 us.
380 // Timer wrap-arounds are handled correctly by this function.
381 // When the current ACPI timer value is greater than 'Ticks',
382 // the while loop will exit.
384 while (((Ticks
- IoBitFieldRead32 (TimerAddr
, 0, 23)) & BIT23
) == 0) {
388 EndTSC
= AsmReadTsc (); // TSC value 101.4 us later
390 TscFrequency
= MultU64x32 (
391 (EndTSC
- StartTSC
), // Number of TSC counts in 101.4 us
392 9861 // Number of 101.4 us in a second
395 SetInterruptState (InterruptState
);