2 A Timer Library implementation which uses the Time Stamp Counter in the processor.
4 For Pentium 4 processors, Intel Xeon processors (family [0FH], models [03H and higher]);
5 for Intel Core Solo and Intel Core Duo processors (family [06H], model [0EH]);
6 for the Intel Xeon processor 5100 series and Intel Core 2 Duo processors (family [06H], model [0FH]);
7 for Intel Core 2 and Intel Xeon processors (family [06H], display_model [17H]);
8 for Intel Atom processors (family [06H], display_model [1CH]):
9 the time-stamp counter increments at a constant rate.
10 That rate may be set by the maximum core-clock to bus-clock ratio of the processor or may be set by
11 the maximum resolved frequency at which the processor is booted. The maximum resolved frequency may
12 differ from the maximum qualified frequency of the processor.
14 The specific processor configuration determines the behavior. Constant TSC behavior ensures that the
15 duration of each clock tick is uniform and supports the use of the TSC as a wall clock timer even if
16 the processor core changes frequency. This is the architectural behavior moving forward.
18 A Processor\92s support for invariant TSC is indicated by CPUID.0x80000007.EDX[8].
20 Copyright (c) 2009 - 2010, Intel Corporation. All rights reserved.<BR>
21 This program and the accompanying materials
22 are licensed and made available under the terms and conditions of the BSD License
23 which accompanies this distribution. The full text of the license may be found at
24 http://opensource.org/licenses/bsd-license.php
26 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
27 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
32 #include <Ich/GenericIch.h>
34 #include <Library/TimerLib.h>
35 #include <Library/BaseLib.h>
36 #include <Library/IoLib.h>
37 #include <Library/PciLib.h>
38 #include <Library/PcdLib.h>
40 STATIC UINT64 mTscFrequency
;
42 #ifndef R_ICH_ACPI_PM1_TMR
43 #define R_ICH_ACPI_PM1_TMR R_ACPI_PM1_TMR
46 /** The constructor function determines the actual TSC frequency.
48 The TSC counting frequency is determined by comparing how far it counts
49 during a 1ms period as determined by the ACPI timer. The ACPI timer is
50 used because it counts at a known frequency.
51 If ACPI I/O space not enabled, this function will enable it. Then the
52 TSC is sampled, followed by waiting for 3579 clocks of the ACPI timer, or 1ms.
53 The TSC is then sampled again. The difference multiplied by 1000 is the TSC
54 frequency. There will be a small error because of the overhead of reading
55 the ACPI timer. An attempt is made to determine and compensate for this error.
56 This function will always return RETURN_SUCCESS.
58 @retval RETURN_SUCCESS The constructor always returns RETURN_SUCCESS.
63 TscTimerLibConstructor (
73 // If ACPI I/O space is not enabled yet, program ACPI I/O base address and enable it.
75 if ((PciRead8 (PCI_ICH_LPC_ADDRESS (R_ICH_LPC_ACPI_CNT
)) & B_ICH_LPC_ACPI_CNT_ACPI_EN
) == 0) {
76 PciWrite16 (PCI_ICH_LPC_ADDRESS (R_ICH_LPC_ACPI_BASE
), PcdGet16 (PcdPerfPkgAcpiIoPortBaseAddress
));
77 PciOr8 (PCI_ICH_LPC_ADDRESS (R_ICH_LPC_ACPI_CNT
), B_ICH_LPC_ACPI_CNT_ACPI_EN
);
80 TimerAddr
= PcdGet16 (PcdPerfPkgAcpiIoPortBaseAddress
) + R_ACPI_PM1_TMR
; // Locate the ACPI Timer
81 Ticks
= IoRead32( TimerAddr
) + (3579); // Set Ticks to 1ms in the future
82 StartTSC
= AsmReadTsc(); // Get base value for the TSC
84 // Wait until the ACPI timer has counted 1ms.
85 // Timer wrap-arounds are handled correctly by this function.
86 // When the current ACPI timer value is greater than 'Ticks', the while loop will exit.
88 while (((Ticks
- IoRead32( TimerAddr
)) & BIT23
) == 0) {
91 EndTSC
= AsmReadTsc(); // TSC value 1ms later
93 mTscFrequency
= MultU64x32 (
94 (EndTSC
- StartTSC
), // Number of TSC counts in 1ms
95 1000 // Number of ms in a second
98 // mTscFrequency is now equal to the number of TSC counts per second
100 return RETURN_SUCCESS
;
103 /** Stalls the CPU for at least the given number of ticks.
105 Stalls the CPU for at least the given number of ticks. It's invoked by
106 MicroSecondDelay() and NanoSecondDelay().
108 @param[in] Delay A period of time to delay in ticks.
120 // The target timer count is calculated here
122 Ticks
= AsmReadTsc() + Delay
;
125 // Wait until time out
126 // Timer wrap-arounds are NOT handled correctly by this function.
127 // Thus, this function must be called within 10 years of reset since
128 // Intel guarantees a minimum of 10 years before the TSC wraps.
130 while (AsmReadTsc() <= Ticks
) CpuPause();
133 /** Stalls the CPU for at least the specified number of MicroSeconds.
135 @param[in] MicroSeconds The minimum number of microseconds to delay.
137 @return The value of MicroSeconds input.
143 IN UINTN MicroSeconds
158 /** Stalls the CPU for at least the specified number of NanoSeconds.
160 @param[in] NanoSeconds The minimum number of nanoseconds to delay.
162 @return The value of NanoSeconds input.
183 /** Retrieves the current value of the 64-bit free running Time-Stamp counter.
185 The time-stamp counter (as implemented in the P6 family, Pentium, Pentium M,
186 Pentium 4, Intel Xeon, Intel Core Solo and Intel Core Duo processors and
187 later processors) is a 64-bit counter that is set to 0 following a RESET of
188 the processor. Following a RESET, the counter increments even when the
189 processor is halted by the HLT instruction or the external STPCLK# pin. Note
190 that the assertion of the external DPSLP# pin may cause the time-stamp
193 The properties of the counter can be retrieved by the
194 GetPerformanceCounterProperties() function.
196 @return The current value of the free running performance counter.
201 GetPerformanceCounter (
208 /** Retrieves the 64-bit frequency in Hz and the range of performance counter
211 If StartValue is not NULL, then the value that the performance counter starts
212 with, 0x0, is returned in StartValue. If EndValue is not NULL, then the value
213 that the performance counter end with, 0xFFFFFFFFFFFFFFFF, is returned in
216 The 64-bit frequency of the performance counter, in Hz, is always returned.
217 To determine average processor clock frequency, Intel recommends the use of
218 EMON logic to count processor core clocks over the period of time for which
219 the average is required.
222 @param[out] StartValue Pointer to where the performance counter's starting value is saved, or NULL.
223 @param[out] EndValue Pointer to where the performance counter's ending value is saved, or NULL.
225 @return The frequency in Hz.
230 GetPerformanceCounterProperties (
231 OUT UINT64
*StartValue
, OPTIONAL
232 OUT UINT64
*EndValue OPTIONAL
235 if (StartValue
!= NULL
) {
238 if (EndValue
!= NULL
) {
239 *EndValue
= 0xFFFFFFFFFFFFFFFFull
;
242 return mTscFrequency
;