2 /******************************************************************************
4 * Name: hwtimer.c - ACPI Power Management Timer Interface
6 *****************************************************************************/
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45 #include <contrib/dev/acpica/include/acpi.h>
46 #include <contrib/dev/acpica/include/accommon.h>
48 #define _COMPONENT ACPI_HARDWARE
49 ACPI_MODULE_NAME ("hwtimer")
52 /******************************************************************************
54 * FUNCTION: AcpiGetTimerResolution
56 * PARAMETERS: Resolution - Where the resolution is returned
58 * RETURN: Status and timer resolution
60 * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
62 ******************************************************************************/
65 AcpiGetTimerResolution (
68 ACPI_FUNCTION_TRACE (AcpiGetTimerResolution);
73 return_ACPI_STATUS (AE_BAD_PARAMETER);
76 if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0)
85 return_ACPI_STATUS (AE_OK);
88 ACPI_EXPORT_SYMBOL (AcpiGetTimerResolution)
91 /******************************************************************************
93 * FUNCTION: AcpiGetTimer
95 * PARAMETERS: Ticks - Where the timer value is returned
97 * RETURN: Status and current timer value (ticks)
99 * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
101 ******************************************************************************/
110 ACPI_FUNCTION_TRACE (AcpiGetTimer);
115 return_ACPI_STATUS (AE_BAD_PARAMETER);
118 Status = AcpiHwRead (Ticks, &AcpiGbl_FADT.XPmTimerBlock);
120 return_ACPI_STATUS (Status);
123 ACPI_EXPORT_SYMBOL (AcpiGetTimer)
126 /******************************************************************************
128 * FUNCTION: AcpiGetTimerDuration
130 * PARAMETERS: StartTicks - Starting timestamp
131 * EndTicks - End timestamp
132 * TimeElapsed - Where the elapsed time is returned
134 * RETURN: Status and TimeElapsed
136 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
137 * PM Timer time stamps, taking into account the possibility of
138 * rollovers, the timer resolution, and timer frequency.
140 * The PM Timer's clock ticks at roughly 3.6 times per
141 * _microsecond_, and its clock continues through Cx state
142 * transitions (unlike many CPU timestamp counters) -- making it
143 * a versatile and accurate timer.
145 * Note that this function accommodates only a single timer
146 * rollover. Thus for 24-bit timers, this function should only
147 * be used for calculating durations less than ~4.6 seconds
148 * (~20 minutes for 32-bit timers) -- calculations below:
150 * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
151 * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
153 ******************************************************************************/
156 AcpiGetTimerDuration (
166 ACPI_FUNCTION_TRACE (AcpiGetTimerDuration);
171 return_ACPI_STATUS (AE_BAD_PARAMETER);
175 * Compute Tick Delta:
176 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
178 if (StartTicks < EndTicks)
180 DeltaTicks = EndTicks - StartTicks;
182 else if (StartTicks > EndTicks)
184 if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0)
188 DeltaTicks = (((0x00FFFFFF - StartTicks) + EndTicks) & 0x00FFFFFF);
194 DeltaTicks = (0xFFFFFFFF - StartTicks) + EndTicks;
197 else /* StartTicks == EndTicks */
200 return_ACPI_STATUS (AE_OK);
204 * Compute Duration (Requires a 64-bit multiply and divide):
206 * TimeElapsed = (DeltaTicks * 1000000) / PM_TIMER_FREQUENCY;
208 Status = AcpiUtShortDivide (((UINT64) DeltaTicks) * 1000000,
209 PM_TIMER_FREQUENCY, &Quotient, NULL);
211 *TimeElapsed = (UINT32) Quotient;
212 return_ACPI_STATUS (Status);
215 ACPI_EXPORT_SYMBOL (AcpiGetTimerDuration)