// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/******************************************************************************
*
* Module Name: evglock - Global Lock support
*
* Copyright (C) 2000 - 2023, Intel Corp.
*
*****************************************************************************/
#include <acpi/acpi.h>
#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 */
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