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

 *

 * Module Name: evglock - Global Lock support

 *

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

/*

 * Copyright (C) 2000 - 2015, Intel Corp.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions, and the following disclaimer,

 *    without modification.

 * 2. Redistributions in binary form must reproduce at minimum a disclaimer

 *    substantially similar to the "NO WARRANTY" disclaimer below

 *    ("Disclaimer") and any redistribution must be conditioned upon

 *    including a substantially similar Disclaimer requirement for further

 *    binary redistribution.

 * 3. Neither the names of the above-listed copyright holders nor the names

 *    of any contributors may be used to endorse or promote products derived

 *    from this software without specific prior written permission.

 *

 * Alternatively, this software may be distributed under the terms of the

 * GNU General Public License ("GPL") version 2 as published by the Free

 * Software Foundation.

 *

 * NO WARRANTY

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING

 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

 * POSSIBILITY OF SUCH DAMAGES.

 */

#include 

#include "accommon.h"

#include "acevents.h"

#include "acinterp.h"

#define _COMPONENT          ACPI_EVENTS

ACPI_MODULE_NAME("evglock")

#if (!ACPI_REDUCED_HARDWARE)	/* Entire module */

/* Local prototypes */

static u32 acpi_ev_global_lock_handler(void *context);

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

 *

 * FUNCTION:    acpi_ev_init_global_lock_handler

 *

 * PARAMETERS:  None

 *

 * RETURN:      Status

 *

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

 *

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

acpi_status acpi_ev_init_global_lock_handler(void)

{

	acpi_status status;

	ACPI_FUNCTION_TRACE(ev_init_global_lock_handler);

	/* If Hardware Reduced flag is set, there is no global lock */

	if (acpi_gbl_reduced_hardware) {

		return_ACPI_STATUS(AE_OK);

	}

	/* Attempt installation of the global lock handler */

	status = acpi_install_fixed_event_handler(ACPI_EVENT_GLOBAL,

						  acpi_ev_global_lock_handler,

						  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.

	 */

	acpi_gbl_global_lock_present = 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 = acpi_os_create_lock(&acpi_gbl_global_lock_pending_lock);

	if (ACPI_FAILURE(status)) {

		return_ACPI_STATUS(status);

	}

	acpi_gbl_global_lock_pending = FALSE;

	acpi_gbl_global_lock_present = TRUE;

	return_ACPI_STATUS(status);

}

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

 *

 * FUNCTION:    acpi_ev_remove_global_lock_handler

 *

 * PARAMETERS:  None

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Remove the handler for the Global Lock

 *

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

acpi_status acpi_ev_remove_global_lock_handler(void)

{

	acpi_status status;

	ACPI_FUNCTION_TRACE(ev_remove_global_lock_handler);

	acpi_gbl_global_lock_present = FALSE;

	status = acpi_remove_fixed_event_handler(ACPI_EVENT_GLOBAL,

						 acpi_ev_global_lock_handler);

	acpi_os_delete_lock(acpi_gbl_global_lock_pending_lock);

	return_ACPI_STATUS(status);

}

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

 *

 * FUNCTION:    acpi_ev_global_lock_handler

 *

 * 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 u32 acpi_ev_global_lock_handler(void *context)

{

	acpi_status status;

	acpi_cpu_flags flags;

	flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);

	/*

	 * 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 (!acpi_gbl_global_lock_pending) {

		goto cleanup_and_exit;

	}

	/*

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

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

	 */

	status = acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore, 1);

	if (ACPI_FAILURE(status)) {

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

	}

	acpi_gbl_global_lock_pending = FALSE;

cleanup_and_exit:

	acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);

	return (ACPI_INTERRUPT_HANDLED);

}

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

 *

 * FUNCTION:    acpi_ev_acquire_global_lock

 *

 * 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 acpi_ev_acquire_global_lock(u16 timeout)

{

	acpi_cpu_flags flags;

	acpi_status status;

	u8 acquired = FALSE;

	ACPI_FUNCTION_TRACE(ev_acquire_global_lock);

	/*

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

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

	 */

	status =

	    acpi_ex_system_wait_mutex(acpi_gbl_global_lock_mutex->mutex.

				      os_mutex, 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 acpi_acquire_global_lock interfaces. The

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

	 * regardless of where the acquisition request originated.

	 */

	acpi_gbl_global_lock_handle++;

	if (acpi_gbl_global_lock_handle == 0) {

		acpi_gbl_global_lock_handle = 1;

	}

	/*

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

	 * treat the lock as a standard mutex.

	 */

	if (!acpi_gbl_global_lock_present) {

		acpi_gbl_global_lock_acquired = TRUE;

		return_ACPI_STATUS(AE_OK);

	}

	flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);

	do {

		/* Attempt to acquire the actual hardware lock */

		ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_FACS, acquired);

		if (acquired) {

			acpi_gbl_global_lock_acquired = 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.

		 */

		acpi_gbl_global_lock_pending = TRUE;

		acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, 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 =

		    acpi_ex_system_wait_semaphore

		    (acpi_gbl_global_lock_semaphore, ACPI_WAIT_FOREVER);

		flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);

	} while (ACPI_SUCCESS(status));

	acpi_gbl_global_lock_pending = FALSE;

	acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);

	return_ACPI_STATUS(status);

}

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

 *

 * FUNCTION:    acpi_ev_release_global_lock

 *

 * PARAMETERS:  None

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Releases ownership of the Global Lock.

 *

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

acpi_status acpi_ev_release_global_lock(void)

{

	u8 pending = FALSE;

	acpi_status status = AE_OK;

	ACPI_FUNCTION_TRACE(ev_release_global_lock);

	/* Lock must be already acquired */

	if (!acpi_gbl_global_lock_acquired) {

		ACPI_WARNING((AE_INFO,

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

		return_ACPI_STATUS(AE_NOT_ACQUIRED);

	}

	if (acpi_gbl_global_lock_present) {

		/* Allow any thread to release the lock */

		ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_FACS, pending);

		/*

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

		 * register

		 */

		if (pending) {

			status =

			    acpi_write_bit_register

			    (ACPI_BITREG_GLOBAL_LOCK_RELEASE,

			     ACPI_ENABLE_EVENT);

		}

		ACPI_DEBUG_PRINT((ACPI_DB_EXEC,

				  "Released hardware Global Lock\n"));

	}

	acpi_gbl_global_lock_acquired = FALSE;

	/* Release the local GL mutex */

	acpi_os_release_mutex(acpi_gbl_global_lock_mutex->mutex.os_mutex);

	return_ACPI_STATUS(status);

}

#endif				/* !ACPI_REDUCED_HARDWARE */