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/******************************************************************************

 *

 * Module Name: evglock - Global Lock support

 *

 *****************************************************************************/

/******************************************************************************

 *

 * 1. Copyright Notice

 *

 * Some or all of this work - Copyright (c) 1999 - 2011, 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"

#include "acevents.h"

#include "acinterp.h"

#define _COMPONENT          ACPI_EVENTS

        ACPI_MODULE_NAME    ("evglock")

/* Local prototypes */

static UINT32

AcpiEvGlobalLockHandler (

    void                    *Context);

/*******************************************************************************

 *

 * FUNCTION:    AcpiEvInitGlobalLockHandler

 *

 * PARAMETERS:  None

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Install a handler for the global lock release event

 *

 ******************************************************************************/

ACPI_STATUS

AcpiEvInitGlobalLockHandler (

    void)

{

    ACPI_STATUS             Status;

    ACPI_FUNCTION_TRACE (EvInitGlobalLockHandler);

    /* Attempt installation of the global lock handler */

    Status = AcpiInstallFixedEventHandler (ACPI_EVENT_GLOBAL,

                AcpiEvGlobalLockHandler, NULL);

    /*

     * If the global lock does not exist on this platform, the attempt to

     * enable GBL_STATUS will fail (the GBL_ENABLE bit will not stick).

     * Map to AE_OK, but mark global lock as not present. Any attempt to

     * actually use the global lock will be flagged with an error.

     */

    AcpiGbl_GlobalLockPresent = FALSE;

    if (Status == AE_NO_HARDWARE_RESPONSE)

    {

        ACPI_ERROR ((AE_INFO,

            "No response from Global Lock hardware, disabling lock"));

        return_ACPI_STATUS (AE_OK);

    }

    Status = AcpiOsCreateLock (&AcpiGbl_GlobalLockPendingLock);

    if (ACPI_FAILURE (Status))

    {

        return_ACPI_STATUS (Status);

    }

    AcpiGbl_GlobalLockPending = FALSE;

    AcpiGbl_GlobalLockPresent = TRUE;

    return_ACPI_STATUS (Status);

}

/*******************************************************************************

 *

 * FUNCTION:    AcpiEvRemoveGlobalLockHandler

 *

 * PARAMETERS:  None

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Remove the handler for the Global Lock

 *

 ******************************************************************************/

ACPI_STATUS

AcpiEvRemoveGlobalLockHandler (

    void)

{

    ACPI_STATUS             Status;

    ACPI_FUNCTION_TRACE (EvRemoveGlobalLockHandler);

    AcpiGbl_GlobalLockPresent = FALSE;

    Status = AcpiRemoveFixedEventHandler (ACPI_EVENT_GLOBAL,

                AcpiEvGlobalLockHandler);

    return_ACPI_STATUS (Status);

}

/*******************************************************************************

 *

 * FUNCTION:    AcpiEvGlobalLockHandler

 *

 * PARAMETERS:  Context         - From thread interface, not used

 *

 * RETURN:      ACPI_INTERRUPT_HANDLED

 *

 * DESCRIPTION: Invoked directly from the SCI handler when a global lock

 *              release interrupt occurs. If there is actually a pending

 *              request for the lock, signal the waiting thread.

 *

 ******************************************************************************/

static UINT32

AcpiEvGlobalLockHandler (

    void                    *Context)

{

    ACPI_STATUS             Status;

    ACPI_CPU_FLAGS          Flags;

    Flags = AcpiOsAcquireLock (AcpiGbl_GlobalLockPendingLock);

    /*

     * If a request for the global lock is not actually pending,

     * we are done. This handles "spurious" global lock interrupts

     * which are possible (and have been seen) with bad BIOSs.

     */

    if (!AcpiGbl_GlobalLockPending)

    {

        goto CleanupAndExit;

    }

    /*

     * Send a unit to the global lock semaphore. The actual acquisition

     * of the global lock will be performed by the waiting thread.

     */

    Status = AcpiOsSignalSemaphore (AcpiGbl_GlobalLockSemaphore, 1);

    if (ACPI_FAILURE (Status))

    {

        ACPI_ERROR ((AE_INFO, "Could not signal Global Lock semaphore"));

    }

    AcpiGbl_GlobalLockPending = FALSE;

CleanupAndExit:

    AcpiOsReleaseLock (AcpiGbl_GlobalLockPendingLock, Flags);

    return (ACPI_INTERRUPT_HANDLED);

}

/******************************************************************************

 *

 * FUNCTION:    AcpiEvAcquireGlobalLock

 *

 * PARAMETERS:  Timeout         - Max time to wait for the lock, in millisec.

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Attempt to gain ownership of the Global Lock.

 *

 * MUTEX:       Interpreter must be locked

 *

 * Note: The original implementation allowed multiple threads to "acquire" the

 * Global Lock, and the OS would hold the lock until the last thread had

 * released it. However, this could potentially starve the BIOS out of the

 * lock, especially in the case where there is a tight handshake between the

 * Embedded Controller driver and the BIOS. Therefore, this implementation

 * allows only one thread to acquire the HW Global Lock at a time, and makes

 * the global lock appear as a standard mutex on the OS side.

 *

 *****************************************************************************/

ACPI_STATUS

AcpiEvAcquireGlobalLock (

    UINT16                  Timeout)

{

    ACPI_CPU_FLAGS          Flags;

    ACPI_STATUS             Status;

    BOOLEAN                 Acquired = FALSE;

    ACPI_FUNCTION_TRACE (EvAcquireGlobalLock);

    /*

     * Only one thread can acquire the GL at a time, the GlobalLockMutex

     * enforces this. This interface releases the interpreter if we must wait.

     */

    Status = AcpiExSystemWaitMutex (AcpiGbl_GlobalLockMutex->Mutex.OsMutex,

                Timeout);

    if (ACPI_FAILURE (Status))

    {

        return_ACPI_STATUS (Status);

    }

    /*

     * Update the global lock handle and check for wraparound. The handle is

     * only used for the external global lock interfaces, but it is updated

     * here to properly handle the case where a single thread may acquire the

     * lock via both the AML and the AcpiAcquireGlobalLock interfaces. The

     * handle is therefore updated on the first acquire from a given thread

     * regardless of where the acquisition request originated.

     */

    AcpiGbl_GlobalLockHandle++;

    if (AcpiGbl_GlobalLockHandle == 0)

    {

        AcpiGbl_GlobalLockHandle = 1;

    }

    /*

     * Make sure that a global lock actually exists. If not, just

     * treat the lock as a standard mutex.

     */

    if (!AcpiGbl_GlobalLockPresent)

    {

        AcpiGbl_GlobalLockAcquired = TRUE;

        return_ACPI_STATUS (AE_OK);

    }

    Flags = AcpiOsAcquireLock (AcpiGbl_GlobalLockPendingLock);

    do

    {

        /* Attempt to acquire the actual hardware lock */

        ACPI_ACQUIRE_GLOBAL_LOCK (AcpiGbl_FACS, Acquired);

        if (Acquired)

        {

            AcpiGbl_GlobalLockAcquired = TRUE;

            ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,

                "Acquired hardware Global Lock\n"));

            break;

        }

        /*

         * Did not get the lock. The pending bit was set above, and

         * we must now wait until we receive the global lock

         * released interrupt.

         */

        AcpiGbl_GlobalLockPending = TRUE;

        AcpiOsReleaseLock (AcpiGbl_GlobalLockPendingLock, Flags);

        ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,

            "Waiting for hardware Global Lock\n"));

        /*

         * Wait for handshake with the global lock interrupt handler.

         * This interface releases the interpreter if we must wait.

         */

        Status = AcpiExSystemWaitSemaphore (AcpiGbl_GlobalLockSemaphore,

                    ACPI_WAIT_FOREVER);

        Flags = AcpiOsAcquireLock (AcpiGbl_GlobalLockPendingLock);

    } while (ACPI_SUCCESS (Status));

    AcpiGbl_GlobalLockPending = FALSE;

    AcpiOsReleaseLock (AcpiGbl_GlobalLockPendingLock, Flags);

    return_ACPI_STATUS (Status);

}

/*******************************************************************************

 *

 * FUNCTION:    AcpiEvReleaseGlobalLock

 *

 * PARAMETERS:  None

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Releases ownership of the Global Lock.

 *

 ******************************************************************************/

ACPI_STATUS

AcpiEvReleaseGlobalLock (

    void)

{

    BOOLEAN                 Pending = FALSE;

    ACPI_STATUS             Status = AE_OK;

    ACPI_FUNCTION_TRACE (EvReleaseGlobalLock);

    /* Lock must be already acquired */

    if (!AcpiGbl_GlobalLockAcquired)

    {

        ACPI_WARNING ((AE_INFO,

            "Cannot release the ACPI Global Lock, it has not been acquired"));

        return_ACPI_STATUS (AE_NOT_ACQUIRED);

    }

    if (AcpiGbl_GlobalLockPresent)

    {

        /* Allow any thread to release the lock */

        ACPI_RELEASE_GLOBAL_LOCK (AcpiGbl_FACS, Pending);

        /*

         * If the pending bit was set, we must write GBL_RLS to the control

         * register

         */

        if (Pending)

        {

            Status = AcpiWriteBitRegister (

                        ACPI_BITREG_GLOBAL_LOCK_RELEASE, ACPI_ENABLE_EVENT);

        }

        ACPI_DEBUG_PRINT ((ACPI_DB_EXEC, "Released hardware Global Lock\n"));

    }

    AcpiGbl_GlobalLockAcquired = FALSE;

    /* Release the local GL mutex */

    AcpiOsReleaseMutex (AcpiGbl_GlobalLockMutex->Mutex.OsMutex);

    return_ACPI_STATUS (Status);

}