drivers/acpi/hardware/hwtimer.c

/******************************************************************************
 *
 * Name: hwtimer.c - ACPI Power Management Timer Interface
 *
 *****************************************************************************/

/******************************************************************************
 *
 * 1. Copyright Notice
 *
 * Some or all of this work - Copyright (c) 1999 - 2010, Intel Corp.
 * All rights reserved.
 *
 * 2. License
 *
 * 2.1. This is your license from Intel Corp. under its intellectual property
 * rights.  You may have additional license terms from the party that provided
 * you this software, covering your right to use that party's intellectual
 * property rights.
 *
 * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
 * copy of the source code appearing in this file ("Covered Code") an
 * irrevocable, perpetual, worldwide license under Intel's copyrights in the
 * base code distributed originally by Intel ("Original Intel Code") to copy,
 * make derivatives, distribute, use and display any portion of the Covered
 * Code in any form, with the right to sublicense such rights; and
 *
 * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
 * license (with the right to sublicense), under only those claims of Intel
 * patents that are infringed by the Original Intel Code, to make, use, sell,
 * offer to sell, and import the Covered Code and derivative works thereof
 * solely to the minimum extent necessary to exercise the above copyright
 * license, and in no event shall the patent license extend to any additions
 * to or modifications of the Original Intel Code.  No other license or right
 * is granted directly or by implication, estoppel or otherwise;
 *
 * The above copyright and patent license is granted only if the following
 * conditions are met:
 *
 * 3. Conditions
 *
 * 3.1. Redistribution of Source with Rights to Further Distribute Source.
 * Redistribution of source code of any substantial portion of the Covered
 * Code or modification with rights to further distribute source must include
 * the above Copyright Notice, the above License, this list of Conditions,
 * and the following Disclaimer and Export Compliance provision.  In addition,
 * Licensee must cause all Covered Code to which Licensee contributes to
 * contain a file documenting the changes Licensee made to create that Covered
 * Code and the date of any change.  Licensee must include in that file the
 * documentation of any changes made by any predecessor Licensee.  Licensee
 * must include a prominent statement that the modification is derived,
 * directly or indirectly, from Original Intel Code.
 *
 * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
 * Redistribution of source code of any substantial portion of the Covered
 * Code or modification without rights to further distribute source must
 * include the following Disclaimer and Export Compliance provision in the
 * documentation and/or other materials provided with distribution.  In
 * addition, Licensee may not authorize further sublicense of source of any
 * portion of the Covered Code, and must include terms to the effect that the
 * license from Licensee to its licensee is limited to the intellectual
 * property embodied in the software Licensee provides to its licensee, and
 * not to intellectual property embodied in modifications its licensee may
 * make.
 *
 * 3.3. Redistribution of Executable. Redistribution in executable form of any
 * substantial portion of the Covered Code or modification must reproduce the
 * above Copyright Notice, and the following Disclaimer and Export Compliance
 * provision in the documentation and/or other materials provided with the
 * distribution.
 *
 * 3.4. Intel retains all right, title, and interest in and to the Original
 * Intel Code.
 *
 * 3.5. Neither the name Intel nor any other trademark owned or controlled by
 * Intel shall be used in advertising or otherwise to promote the sale, use or
 * other dealings in products derived from or relating to the Covered Code
 * without prior written authorization from Intel.
 *
 * 4. Disclaimer and Export Compliance
 *
 * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
 * HERE.  ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
 * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT,  ASSISTANCE,
 * INSTALLATION, TRAINING OR OTHER SERVICES.  INTEL WILL NOT PROVIDE ANY
 * UPDATES, ENHANCEMENTS OR EXTENSIONS.  INTEL SPECIFICALLY DISCLAIMS ANY
 * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
 * PARTICULAR PURPOSE.
 *
 * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
 * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
 * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
 * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
 * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
 * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.  THESE LIMITATIONS
 * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
 * LIMITED REMEDY.
 *
 * 4.3. Licensee shall not export, either directly or indirectly, any of this
 * software or system incorporating such software without first obtaining any
 * required license or other approval from the U. S. Department of Commerce or
 * any other agency or department of the United States Government.  In the
 * event Licensee exports any such software from the United States or
 * re-exports any such software from a foreign destination, Licensee shall
 * ensure that the distribution and export/re-export of the software is in
 * compliance with all laws, regulations, orders, or other restrictions of the
 * U.S. Export Administration Regulations. Licensee agrees that neither it nor
 * any of its subsidiaries will export/re-export any technical data, process,
 * software, or service, directly or indirectly, to any country for which the
 * United States government or any agency thereof requires an export license,
 * other governmental approval, or letter of assurance, without first obtaining
 * such license, approval or letter.
 *
 *****************************************************************************/

#include "acpi.h"
#include "accommon.h"

#define _COMPONENT          ACPI_HARDWARE
        ACPI_MODULE_NAME    ("hwtimer")


/******************************************************************************
 *
 * FUNCTION:    AcpiGetTimerResolution
 *
 * PARAMETERS:  Resolution          - Where the resolution is returned
 *
 * RETURN:      Status and timer resolution
 *
 * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
 *
 ******************************************************************************/

ACPI_STATUS
AcpiGetTimerResolution (
    UINT32                  *Resolution)
{
    ACPI_FUNCTION_TRACE (AcpiGetTimerResolution);


    if (!Resolution)
    {
        return_ACPI_STATUS (AE_BAD_PARAMETER);
    }

    if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0)
    {
        *Resolution = 24;
    }
    else
    {
        *Resolution = 32;
    }

    return_ACPI_STATUS (AE_OK);
}

ACPI_EXPORT_SYMBOL (AcpiGetTimerResolution)


/******************************************************************************
 *
 * FUNCTION:    AcpiGetTimer
 *
 * PARAMETERS:  Ticks               - Where the timer value is returned
 *
 * RETURN:      Status and current timer value (ticks)
 *
 * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
 *
 ******************************************************************************/

ACPI_STATUS
AcpiGetTimer (
    UINT32                  *Ticks)
{
    ACPI_STATUS             Status;


    ACPI_FUNCTION_TRACE (AcpiGetTimer);


    if (!Ticks)
    {
        return_ACPI_STATUS (AE_BAD_PARAMETER);
    }

    Status = AcpiHwRead (Ticks, &AcpiGbl_FADT.XPmTimerBlock);

    return_ACPI_STATUS (Status);
}

ACPI_EXPORT_SYMBOL (AcpiGetTimer)


/******************************************************************************
 *
 * FUNCTION:    AcpiGetTimerDuration
 *
 * PARAMETERS:  StartTicks          - Starting timestamp
 *              EndTicks            - End timestamp
 *              TimeElapsed         - Where the elapsed time is returned
 *
 * RETURN:      Status and TimeElapsed
 *
 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
 *              PM Timer time stamps, taking into account the possibility of
 *              rollovers, the timer resolution, and timer frequency.
 *
 *              The PM Timer's clock ticks at roughly 3.6 times per
 *              _microsecond_, and its clock continues through Cx state
 *              transitions (unlike many CPU timestamp counters) -- making it
 *              a versatile and accurate timer.
 *
 *              Note that this function accommodates only a single timer
 *              rollover.  Thus for 24-bit timers, this function should only
 *              be used for calculating durations less than ~4.6 seconds
 *              (~20 minutes for 32-bit timers) -- calculations below:
 *
 *              2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
 *              2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
 *
 ******************************************************************************/

ACPI_STATUS
AcpiGetTimerDuration (
    UINT32                  StartTicks,
    UINT32                  EndTicks,
    UINT32                  *TimeElapsed)
{
    ACPI_STATUS             Status;
    UINT32                  DeltaTicks;
    UINT64                  Quotient;


    ACPI_FUNCTION_TRACE (AcpiGetTimerDuration);


    if (!TimeElapsed)
    {
        return_ACPI_STATUS (AE_BAD_PARAMETER);
    }

    /*
     * Compute Tick Delta:
     * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
     */
    if (StartTicks < EndTicks)
    {
        DeltaTicks = EndTicks - StartTicks;
    }
    else if (StartTicks > EndTicks)
    {
        if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0)
        {
            /* 24-bit Timer */

            DeltaTicks = (((0x00FFFFFF - StartTicks) + EndTicks) & 0x00FFFFFF);
        }
        else
        {
            /* 32-bit Timer */

            DeltaTicks = (0xFFFFFFFF - StartTicks) + EndTicks;
        }
    }
    else /* StartTicks == EndTicks */
    {
        *TimeElapsed = 0;
        return_ACPI_STATUS (AE_OK);
    }

    /*
     * Compute Duration (Requires a 64-bit multiply and divide):
     *
     * TimeElapsed = (DeltaTicks * 1000000) / PM_TIMER_FREQUENCY;
     */
    Status = AcpiUtShortDivide (((UINT64) DeltaTicks) * 1000000,
                PM_TIMER_FREQUENCY, &Quotient, NULL);

    *TimeElapsed = (UINT32) Quotient;
    return_ACPI_STATUS (Status);
}

ACPI_EXPORT_SYMBOL (AcpiGetTimerDuration)

