311 lines
8.7 KiB
C
311 lines
8.7 KiB
C
// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
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/******************************************************************************
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*
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* Module Name: evglock - Global Lock support
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*
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* Copyright (C) 2000 - 2022, Intel Corp.
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*
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*****************************************************************************/
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#include <acpi/acpi.h>
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#include "accommon.h"
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#include "acevents.h"
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#include "acinterp.h"
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#define _COMPONENT ACPI_EVENTS
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ACPI_MODULE_NAME("evglock")
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#if (!ACPI_REDUCED_HARDWARE) /* Entire module */
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/* Local prototypes */
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static u32 acpi_ev_global_lock_handler(void *context);
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/*******************************************************************************
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*
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* FUNCTION: acpi_ev_init_global_lock_handler
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*
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* PARAMETERS: None
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*
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* RETURN: Status
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*
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* DESCRIPTION: Install a handler for the global lock release event
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*
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******************************************************************************/
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acpi_status acpi_ev_init_global_lock_handler(void)
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{
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acpi_status status;
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ACPI_FUNCTION_TRACE(ev_init_global_lock_handler);
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/* If Hardware Reduced flag is set, there is no global lock */
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if (acpi_gbl_reduced_hardware) {
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return_ACPI_STATUS(AE_OK);
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}
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/* Attempt installation of the global lock handler */
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status = acpi_install_fixed_event_handler(ACPI_EVENT_GLOBAL,
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acpi_ev_global_lock_handler,
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NULL);
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/*
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* If the global lock does not exist on this platform, the attempt to
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* enable GBL_STATUS will fail (the GBL_ENABLE bit will not stick).
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* Map to AE_OK, but mark global lock as not present. Any attempt to
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* actually use the global lock will be flagged with an error.
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*/
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acpi_gbl_global_lock_present = FALSE;
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if (status == AE_NO_HARDWARE_RESPONSE) {
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ACPI_ERROR((AE_INFO,
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"No response from Global Lock hardware, disabling lock"));
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return_ACPI_STATUS(AE_OK);
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}
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status = acpi_os_create_lock(&acpi_gbl_global_lock_pending_lock);
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if (ACPI_FAILURE(status)) {
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return_ACPI_STATUS(status);
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}
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acpi_gbl_global_lock_pending = FALSE;
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acpi_gbl_global_lock_present = TRUE;
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return_ACPI_STATUS(status);
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}
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/*******************************************************************************
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*
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* FUNCTION: acpi_ev_remove_global_lock_handler
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*
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* PARAMETERS: None
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*
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* RETURN: Status
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*
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* DESCRIPTION: Remove the handler for the Global Lock
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*
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******************************************************************************/
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acpi_status acpi_ev_remove_global_lock_handler(void)
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{
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acpi_status status;
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ACPI_FUNCTION_TRACE(ev_remove_global_lock_handler);
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acpi_gbl_global_lock_present = FALSE;
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status = acpi_remove_fixed_event_handler(ACPI_EVENT_GLOBAL,
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acpi_ev_global_lock_handler);
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acpi_os_delete_lock(acpi_gbl_global_lock_pending_lock);
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return_ACPI_STATUS(status);
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}
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/*******************************************************************************
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*
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* FUNCTION: acpi_ev_global_lock_handler
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*
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* PARAMETERS: context - From thread interface, not used
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*
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* RETURN: ACPI_INTERRUPT_HANDLED
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*
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* DESCRIPTION: Invoked directly from the SCI handler when a global lock
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* release interrupt occurs. If there is actually a pending
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* request for the lock, signal the waiting thread.
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*
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******************************************************************************/
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static u32 acpi_ev_global_lock_handler(void *context)
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{
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acpi_status status;
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acpi_cpu_flags flags;
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flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
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/*
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* If a request for the global lock is not actually pending,
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* we are done. This handles "spurious" global lock interrupts
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* which are possible (and have been seen) with bad BIOSs.
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*/
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if (!acpi_gbl_global_lock_pending) {
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goto cleanup_and_exit;
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}
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/*
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* Send a unit to the global lock semaphore. The actual acquisition
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* of the global lock will be performed by the waiting thread.
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*/
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status = acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore, 1);
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if (ACPI_FAILURE(status)) {
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ACPI_ERROR((AE_INFO, "Could not signal Global Lock semaphore"));
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}
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acpi_gbl_global_lock_pending = FALSE;
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cleanup_and_exit:
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acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
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return (ACPI_INTERRUPT_HANDLED);
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}
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/******************************************************************************
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*
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* FUNCTION: acpi_ev_acquire_global_lock
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*
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* PARAMETERS: timeout - Max time to wait for the lock, in millisec.
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*
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* RETURN: Status
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*
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* DESCRIPTION: Attempt to gain ownership of the Global Lock.
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*
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* MUTEX: Interpreter must be locked
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*
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* Note: The original implementation allowed multiple threads to "acquire" the
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* Global Lock, and the OS would hold the lock until the last thread had
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* released it. However, this could potentially starve the BIOS out of the
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* lock, especially in the case where there is a tight handshake between the
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* Embedded Controller driver and the BIOS. Therefore, this implementation
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* allows only one thread to acquire the HW Global Lock at a time, and makes
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* the global lock appear as a standard mutex on the OS side.
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*
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*****************************************************************************/
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acpi_status acpi_ev_acquire_global_lock(u16 timeout)
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{
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acpi_cpu_flags flags;
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acpi_status status;
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u8 acquired = FALSE;
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ACPI_FUNCTION_TRACE(ev_acquire_global_lock);
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/*
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* Only one thread can acquire the GL at a time, the global_lock_mutex
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* enforces this. This interface releases the interpreter if we must wait.
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*/
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status =
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acpi_ex_system_wait_mutex(acpi_gbl_global_lock_mutex->mutex.
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os_mutex, timeout);
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if (ACPI_FAILURE(status)) {
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return_ACPI_STATUS(status);
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}
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/*
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* Update the global lock handle and check for wraparound. The handle is
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* only used for the external global lock interfaces, but it is updated
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* here to properly handle the case where a single thread may acquire the
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* lock via both the AML and the acpi_acquire_global_lock interfaces. The
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* handle is therefore updated on the first acquire from a given thread
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* regardless of where the acquisition request originated.
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*/
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acpi_gbl_global_lock_handle++;
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if (acpi_gbl_global_lock_handle == 0) {
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acpi_gbl_global_lock_handle = 1;
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}
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/*
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* Make sure that a global lock actually exists. If not, just
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* treat the lock as a standard mutex.
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*/
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if (!acpi_gbl_global_lock_present) {
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acpi_gbl_global_lock_acquired = TRUE;
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return_ACPI_STATUS(AE_OK);
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}
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flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
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do {
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/* Attempt to acquire the actual hardware lock */
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ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_FACS, acquired);
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if (acquired) {
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acpi_gbl_global_lock_acquired = TRUE;
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ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
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"Acquired hardware Global Lock\n"));
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break;
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}
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/*
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* Did not get the lock. The pending bit was set above, and
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* we must now wait until we receive the global lock
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* released interrupt.
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*/
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acpi_gbl_global_lock_pending = TRUE;
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acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
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ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
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"Waiting for hardware Global Lock\n"));
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/*
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* Wait for handshake with the global lock interrupt handler.
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* This interface releases the interpreter if we must wait.
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*/
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status =
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acpi_ex_system_wait_semaphore
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(acpi_gbl_global_lock_semaphore, ACPI_WAIT_FOREVER);
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flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
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} while (ACPI_SUCCESS(status));
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acpi_gbl_global_lock_pending = FALSE;
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acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
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return_ACPI_STATUS(status);
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}
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/*******************************************************************************
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*
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* FUNCTION: acpi_ev_release_global_lock
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*
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* PARAMETERS: None
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*
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* RETURN: Status
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*
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* DESCRIPTION: Releases ownership of the Global Lock.
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*
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******************************************************************************/
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acpi_status acpi_ev_release_global_lock(void)
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{
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u8 pending = FALSE;
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acpi_status status = AE_OK;
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ACPI_FUNCTION_TRACE(ev_release_global_lock);
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/* Lock must be already acquired */
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if (!acpi_gbl_global_lock_acquired) {
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ACPI_WARNING((AE_INFO,
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"Cannot release the ACPI Global Lock, it has not been acquired"));
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return_ACPI_STATUS(AE_NOT_ACQUIRED);
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}
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if (acpi_gbl_global_lock_present) {
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/* Allow any thread to release the lock */
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ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_FACS, pending);
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/*
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* If the pending bit was set, we must write GBL_RLS to the control
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* register
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*/
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if (pending) {
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status =
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acpi_write_bit_register
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(ACPI_BITREG_GLOBAL_LOCK_RELEASE,
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ACPI_ENABLE_EVENT);
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}
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ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
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"Released hardware Global Lock\n"));
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}
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acpi_gbl_global_lock_acquired = FALSE;
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/* Release the local GL mutex */
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acpi_os_release_mutex(acpi_gbl_global_lock_mutex->mutex.os_mutex);
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return_ACPI_STATUS(status);
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}
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#endif /* !ACPI_REDUCED_HARDWARE */
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