1 /******************************************************************************
3 * Name: hwtimer.c - ACPI Power Management Timer Interface
5 *****************************************************************************/
8 * Copyright (C) 2000 - 2013, Intel Corp.
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12 * modification, are permitted provided that the following conditions
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20 * including a substantially similar Disclaimer requirement for further
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23 * of any contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
26 * Alternatively, this software may be distributed under the terms of the
27 * GNU General Public License ("GPL") version 2 as published by the Free
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44 #include <contrib/dev/acpica/include/acpi.h>
45 #include <contrib/dev/acpica/include/accommon.h>
47 #define _COMPONENT ACPI_HARDWARE
48 ACPI_MODULE_NAME ("hwtimer")
51 #if (!ACPI_REDUCED_HARDWARE) /* Entire module */
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 /* ACPI 5.0A: PM Timer is optional */
120 if (!AcpiGbl_FADT.XPmTimerBlock.Address)
122 return_ACPI_STATUS (AE_SUPPORT);
125 Status = AcpiHwRead (Ticks, &AcpiGbl_FADT.XPmTimerBlock);
126 return_ACPI_STATUS (Status);
129 ACPI_EXPORT_SYMBOL (AcpiGetTimer)
132 /******************************************************************************
134 * FUNCTION: AcpiGetTimerDuration
136 * PARAMETERS: StartTicks - Starting timestamp
137 * EndTicks - End timestamp
138 * TimeElapsed - Where the elapsed time is returned
140 * RETURN: Status and TimeElapsed
142 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
143 * PM Timer time stamps, taking into account the possibility of
144 * rollovers, the timer resolution, and timer frequency.
146 * The PM Timer's clock ticks at roughly 3.6 times per
147 * _microsecond_, and its clock continues through Cx state
148 * transitions (unlike many CPU timestamp counters) -- making it
149 * a versatile and accurate timer.
151 * Note that this function accommodates only a single timer
152 * rollover. Thus for 24-bit timers, this function should only
153 * be used for calculating durations less than ~4.6 seconds
154 * (~20 minutes for 32-bit timers) -- calculations below:
156 * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
157 * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
159 ******************************************************************************/
162 AcpiGetTimerDuration (
172 ACPI_FUNCTION_TRACE (AcpiGetTimerDuration);
177 return_ACPI_STATUS (AE_BAD_PARAMETER);
180 /* ACPI 5.0A: PM Timer is optional */
182 if (!AcpiGbl_FADT.XPmTimerBlock.Address)
184 return_ACPI_STATUS (AE_SUPPORT);
188 * Compute Tick Delta:
189 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
191 if (StartTicks < EndTicks)
193 DeltaTicks = EndTicks - StartTicks;
195 else if (StartTicks > EndTicks)
197 if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0)
201 DeltaTicks = (((0x00FFFFFF - StartTicks) + EndTicks) & 0x00FFFFFF);
207 DeltaTicks = (0xFFFFFFFF - StartTicks) + EndTicks;
210 else /* StartTicks == EndTicks */
213 return_ACPI_STATUS (AE_OK);
217 * Compute Duration (Requires a 64-bit multiply and divide):
219 * TimeElapsed (microseconds) =
220 * (DeltaTicks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
222 Status = AcpiUtShortDivide (((UINT64) DeltaTicks) * ACPI_USEC_PER_SEC,
223 ACPI_PM_TIMER_FREQUENCY, &Quotient, NULL);
225 *TimeElapsed = (UINT32) Quotient;
226 return_ACPI_STATUS (Status);
229 ACPI_EXPORT_SYMBOL (AcpiGetTimerDuration)
231 #endif /* !ACPI_REDUCED_HARDWARE */