evmisc.c

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	if (acquired) {

		/* Got the lock, now wake all threads waiting for it */

		acpi_gbl_global_lock_acquired = TRUE;
		/* Send a unit to the semaphore */

		if (ACPI_FAILURE
		    (acpi_os_signal_semaphore
		     (acpi_gbl_global_lock_semaphore, 1))) {
			ACPI_ERROR((AE_INFO,
				    "Could not signal Global Lock semaphore"));
		}
	}

	return (ACPI_INTERRUPT_HANDLED);
}

/*******************************************************************************
 *
 * 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);

	status =
	    acpi_get_table_by_index(ACPI_TABLE_INDEX_FACS,
				    (struct acpi_table_header **)&facs);
	if (ACPI_FAILURE(status)) {
		return_ACPI_STATUS(status);
	}

	acpi_gbl_global_lock_present = TRUE;
	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.
	 */
	if (status == AE_NO_HARDWARE_RESPONSE) {
		ACPI_ERROR((AE_INFO,
			    "No response from Global Lock hardware, disabling lock"));

		acpi_gbl_global_lock_present = FALSE;
		status = AE_OK;
	}

	return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ev_remove_global_lock_handler
 *
 * PARAMETERS:  None
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Remove the handler for the Global Lock
 *
 ******************************************************************************/

static 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);

	return_ACPI_STATUS(status);
}

/******************************************************************************
 *
 * 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.
 *
 *****************************************************************************/
static acpi_thread_id acpi_ev_global_lock_thread_id;
static int acpi_ev_global_lock_acquired;

acpi_status acpi_ev_acquire_global_lock(u16 timeout)
{
	acpi_status status = AE_OK;
	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, 0);
	if (status == AE_TIME) {
		if (acpi_ev_global_lock_thread_id == acpi_os_get_thread_id()) {
			acpi_ev_global_lock_acquired++;
			return AE_OK;
		}
	}

	if (ACPI_FAILURE(status)) {
		status =
		    acpi_ex_system_wait_mutex(acpi_gbl_global_lock_mutex,
					      timeout);
	}
	if (ACPI_FAILURE(status)) {
		return_ACPI_STATUS(status);
	}

	acpi_ev_global_lock_thread_id = acpi_os_get_thread_id();
	acpi_ev_global_lock_acquired++;

	/*
	 * 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);
	}

	/* Attempt to acquire the actual hardware lock */

	ACPI_ACQUIRE_GLOBAL_LOCK(facs, acquired);
	if (acquired) {

		/* We got the lock */

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

		acpi_gbl_global_lock_acquired = TRUE;
		return_ACPI_STATUS(AE_OK);
	}

	/*
	 * Did not get the lock. The pending bit was set above, and we must now
	 * wait until we get the global lock released interrupt.
	 */
	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);

	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);
	}

	acpi_ev_global_lock_acquired--;
	if (acpi_ev_global_lock_acquired > 0) {
		return AE_OK;
	}

	if (acpi_gbl_global_lock_present) {

		/* Allow any thread to release the lock */

		ACPI_RELEASE_GLOBAL_LOCK(facs, pending);

		/*
		 * If the pending bit was set, we must write GBL_RLS to the control
		 * register
		 */
		if (pending) {
			status =
			    acpi_set_register(ACPI_BITREG_GLOBAL_LOCK_RELEASE,
					      1);
		}

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

	acpi_gbl_global_lock_acquired = FALSE;

	/* Release the local GL mutex */
	acpi_ev_global_lock_thread_id = NULL;
	acpi_ev_global_lock_acquired = 0;
	acpi_os_release_mutex(acpi_gbl_global_lock_mutex);
	return_ACPI_STATUS(status);
}

/******************************************************************************
 *
 * FUNCTION:    acpi_ev_terminate
 *
 * PARAMETERS:  none
 *
 * RETURN:      none
 *
 * DESCRIPTION: Disable events and free memory allocated for table storage.
 *
 ******************************************************************************/

void acpi_ev_terminate(void)
{
	acpi_native_uint i;
	acpi_status status;

	ACPI_FUNCTION_TRACE(ev_terminate);

	if (acpi_gbl_events_initialized) {
		/*
		 * Disable all event-related functionality.
		 * In all cases, on error, print a message but obviously we don't abort.
		 */

		/* Disable all fixed events */

		for (i = 0; i < ACPI_NUM_FIXED_EVENTS; i++) {
			status = acpi_disable_event((u32) i, 0);
			if (ACPI_FAILURE(status)) {
				ACPI_ERROR((AE_INFO,
					    "Could not disable fixed event %d",
					    (u32) i));
			}
		}

		/* Disable all GPEs in all GPE blocks */

		status = acpi_ev_walk_gpe_list(acpi_hw_disable_gpe_block);

		/* Remove SCI handler */

		status = acpi_ev_remove_sci_handler();
		if (ACPI_FAILURE(status)) {
			ACPI_ERROR((AE_INFO, "Could not remove SCI handler"));
		}

		status = acpi_ev_remove_global_lock_handler();
		if (ACPI_FAILURE(status)) {
			ACPI_ERROR((AE_INFO,
				    "Could not remove Global Lock handler"));
		}
	}

	/* Deallocate all handler objects installed within GPE info structs */

	status = acpi_ev_walk_gpe_list(acpi_ev_delete_gpe_handlers);

	/* Return to original mode if necessary */

	if (acpi_gbl_original_mode == ACPI_SYS_MODE_LEGACY) {
		status = acpi_disable();
		if (ACPI_FAILURE(status)) {
			ACPI_WARNING((AE_INFO, "AcpiDisable failed"));
		}
	}
	return_VOID;
}