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310 lines
8.7 KiB
310 lines
8.7 KiB
// 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 - 2021, 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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