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Bob Moore
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Len Brown
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May 10, 2011
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/****************************************************************************** | ||
* | ||
* Module Name: evglock - Global Lock support | ||
* | ||
*****************************************************************************/ | ||
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||
/* | ||
* Copyright (C) 2000 - 2011, 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. | ||
*/ | ||
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#include <acpi/acpi.h> | ||
#include "accommon.h" | ||
#include "acevents.h" | ||
#include "acinterp.h" | ||
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#define _COMPONENT ACPI_EVENTS | ||
ACPI_MODULE_NAME("evglock") | ||
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/* Local prototypes */ | ||
static u32 acpi_ev_global_lock_handler(void *context); | ||
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/******************************************************************************* | ||
* | ||
* FUNCTION: acpi_ev_init_global_lock_handler | ||
* | ||
* PARAMETERS: None | ||
* | ||
* RETURN: Status | ||
* | ||
* DESCRIPTION: Install a handler for the global lock release event | ||
* | ||
******************************************************************************/ | ||
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acpi_status acpi_ev_init_global_lock_handler(void) | ||
{ | ||
acpi_status status; | ||
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ACPI_FUNCTION_TRACE(ev_init_global_lock_handler); | ||
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/* Attempt installation of the global lock handler */ | ||
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status = acpi_install_fixed_event_handler(ACPI_EVENT_GLOBAL, | ||
acpi_ev_global_lock_handler, | ||
NULL); | ||
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/* | ||
* 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")); | ||
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return_ACPI_STATUS(AE_OK); | ||
} | ||
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status = acpi_os_create_lock(&acpi_gbl_global_lock_pending_lock); | ||
if (ACPI_FAILURE(status)) { | ||
return_ACPI_STATUS(status); | ||
} | ||
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acpi_gbl_global_lock_pending = FALSE; | ||
acpi_gbl_global_lock_present = TRUE; | ||
return_ACPI_STATUS(status); | ||
} | ||
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/******************************************************************************* | ||
* | ||
* FUNCTION: acpi_ev_remove_global_lock_handler | ||
* | ||
* PARAMETERS: None | ||
* | ||
* RETURN: Status | ||
* | ||
* DESCRIPTION: Remove the handler for the Global Lock | ||
* | ||
******************************************************************************/ | ||
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acpi_status acpi_ev_remove_global_lock_handler(void) | ||
{ | ||
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; | ||
status = acpi_remove_fixed_event_handler(ACPI_EVENT_GLOBAL, | ||
acpi_ev_global_lock_handler); | ||
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return_ACPI_STATUS(status); | ||
} | ||
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/******************************************************************************* | ||
* | ||
* 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. | ||
* | ||
******************************************************************************/ | ||
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static u32 acpi_ev_global_lock_handler(void *context) | ||
{ | ||
acpi_status status; | ||
acpi_cpu_flags flags; | ||
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flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock); | ||
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/* | ||
* 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; | ||
} | ||
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/* | ||
* 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")); | ||
} | ||
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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); | ||
return (ACPI_INTERRUPT_HANDLED); | ||
} | ||
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/****************************************************************************** | ||
* | ||
* 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. | ||
* | ||
*****************************************************************************/ | ||
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acpi_status acpi_ev_acquire_global_lock(u16 timeout) | ||
{ | ||
acpi_cpu_flags flags; | ||
acpi_status status; | ||
u8 acquired = FALSE; | ||
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ACPI_FUNCTION_TRACE(ev_acquire_global_lock); | ||
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/* | ||
* 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); | ||
} | ||
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/* | ||
* 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; | ||
} | ||
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/* | ||
* 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); | ||
} | ||
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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); | ||
if (acquired) { | ||
acpi_gbl_global_lock_acquired = TRUE; | ||
ACPI_DEBUG_PRINT((ACPI_DB_EXEC, | ||
"Acquired hardware Global Lock\n")); | ||
break; | ||
} | ||
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/* | ||
* 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); | ||
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ACPI_DEBUG_PRINT((ACPI_DB_EXEC, | ||
"Waiting for hardware Global Lock\n")); | ||
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/* | ||
* 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); | ||
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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; | ||
acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags); | ||
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return_ACPI_STATUS(status); | ||
} | ||
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/******************************************************************************* | ||
* | ||
* FUNCTION: acpi_ev_release_global_lock | ||
* | ||
* PARAMETERS: None | ||
* | ||
* RETURN: Status | ||
* | ||
* DESCRIPTION: Releases ownership of the Global Lock. | ||
* | ||
******************************************************************************/ | ||
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acpi_status acpi_ev_release_global_lock(void) | ||
{ | ||
u8 pending = FALSE; | ||
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) { | ||
ACPI_WARNING((AE_INFO, | ||
"Cannot release the ACPI Global Lock, it has not been acquired")); | ||
return_ACPI_STATUS(AE_NOT_ACQUIRED); | ||
} | ||
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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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/* | ||
* 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); | ||
} | ||
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ACPI_DEBUG_PRINT((ACPI_DB_EXEC, | ||
"Released hardware Global Lock\n")); | ||
} | ||
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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); | ||
return_ACPI_STATUS(status); | ||
} |
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