evglock.c

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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);
}