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 /******************************************************************************
  *
  * Name: hwtimer.c - ACPI Power Management Timer Interface
  *
  *****************************************************************************/
 
 /******************************************************************************
  *
  * 1. Copyright Notice
  *
  * Some or all of this work - Copyright (c) 1999 - 2009, 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;
     ACPI_INTEGER            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)