};
#endif
+/* Pointer to FACS needed for the Global Lock */
+
+static struct acpi_table_facs *facs = NULL;
+
/* Local prototypes */
static void ACPI_SYSTEM_XFACE acpi_ev_notify_dispatch(void *context);
-static void ACPI_SYSTEM_XFACE acpi_ev_global_lock_thread(void *context);
-
static u32 acpi_ev_global_lock_handler(void *context);
/*******************************************************************************
acpi_ut_delete_generic_state(notify_info);
}
-/*******************************************************************************
- *
- * FUNCTION: acpi_ev_global_lock_thread
- *
- * PARAMETERS: Context - From thread interface, not used
- *
- * RETURN: None
- *
- * DESCRIPTION: Invoked by SCI interrupt handler upon acquisition of the
- * Global Lock. Simply signal all threads that are waiting
- * for the lock.
- *
- ******************************************************************************/
-
-static void ACPI_SYSTEM_XFACE acpi_ev_global_lock_thread(void *context)
-{
- acpi_status status;
-
- /* Signal threads that are waiting for the lock */
-
- if (acpi_gbl_global_lock_thread_count) {
-
- /* Send sufficient units to the semaphore */
-
- status =
- acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore,
- acpi_gbl_global_lock_thread_count);
- if (ACPI_FAILURE(status)) {
- ACPI_ERROR((AE_INFO,
- "Could not signal Global Lock semaphore"));
- }
- }
-}
-
/*******************************************************************************
*
* FUNCTION: acpi_ev_global_lock_handler
*
* PARAMETERS: Context - From thread interface, not used
*
- * RETURN: ACPI_INTERRUPT_HANDLED or ACPI_INTERRUPT_NOT_HANDLED
+ * RETURN: ACPI_INTERRUPT_HANDLED
*
* DESCRIPTION: Invoked directly from the SCI handler when a global lock
- * release interrupt occurs. Grab the global lock and queue
- * the global lock thread for execution
+ * release interrupt occurs. Attempt to acquire the global lock,
+ * if successful, signal the thread waiting for the lock.
+ *
+ * NOTE: Assumes that the semaphore can be signaled from interrupt level. If
+ * this is not possible for some reason, a separate thread will have to be
+ * scheduled to do this.
*
******************************************************************************/
static u32 acpi_ev_global_lock_handler(void *context)
{
u8 acquired = FALSE;
- acpi_status status;
/*
- * Attempt to get the lock
+ * Attempt to get the lock.
+ *
* If we don't get it now, it will be marked pending and we will
* take another interrupt when it becomes free.
*/
- ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_common_fACS.global_lock, acquired);
+ ACPI_ACQUIRE_GLOBAL_LOCK(facs, acquired);
if (acquired) {
/* Got the lock, now wake all threads waiting for it */
+
acpi_gbl_global_lock_acquired = TRUE;
- acpi_ev_global_lock_thread(context);
+ /* 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);
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,
*
* 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_FUNCTION_TRACE(ev_acquire_global_lock);
-#ifndef ACPI_APPLICATION
- /* Make sure that we actually have a global lock */
-
- if (!acpi_gbl_global_lock_present) {
- return_ACPI_STATUS(AE_NO_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, timeout);
+ if (ACPI_FAILURE(status)) {
+ return_ACPI_STATUS(status);
}
-#endif
-
- /* One more thread wants the global lock */
-
- acpi_gbl_global_lock_thread_count++;
/*
- * If we (OS side vs. BIOS side) have the hardware lock already,
- * we are done
+ * Make sure that a global lock actually exists. If not, just treat
+ * the lock as a standard mutex.
*/
- if (acpi_gbl_global_lock_acquired) {
+ if (!acpi_gbl_global_lock_present) {
+ acpi_gbl_global_lock_acquired = TRUE;
return_ACPI_STATUS(AE_OK);
}
- /* We must acquire the actual hardware lock */
+ /* Attempt to acquire the actual hardware lock */
- ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_common_fACS.global_lock, acquired);
+ ACPI_ACQUIRE_GLOBAL_LOCK(facs, acquired);
if (acquired) {
/* We got the lock */
ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
- "Acquired the HW Global Lock\n"));
+ "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
+ * 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 the HW Global Lock\n"));
+ ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Waiting for hardware Global Lock\n"));
/*
- * Acquire the global lock semaphore first.
- * Since this wait will block, we must release the interpreter
+ * 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,
- timeout);
+ status = acpi_ex_system_wait_semaphore(acpi_gbl_global_lock_semaphore,
+ ACPI_WAIT_FOREVER);
+
return_ACPI_STATUS(status);
}
ACPI_FUNCTION_TRACE(ev_release_global_lock);
- if (!acpi_gbl_global_lock_thread_count) {
+ /* Lock must be already acquired */
+
+ if (!acpi_gbl_global_lock_acquired) {
ACPI_WARNING((AE_INFO,
- "Cannot release HW Global Lock, it has not been acquired"));
+ "Cannot release the ACPI Global Lock, it has not been acquired"));
return_ACPI_STATUS(AE_NOT_ACQUIRED);
}
- /* One fewer thread has the global lock */
+ if (acpi_gbl_global_lock_present) {
- acpi_gbl_global_lock_thread_count--;
- if (acpi_gbl_global_lock_thread_count) {
+ /* Allow any thread to release the lock */
- /* There are still some threads holding the lock, cannot release */
+ ACPI_RELEASE_GLOBAL_LOCK(facs, pending);
- return_ACPI_STATUS(AE_OK);
+ /*
+ * 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"));
}
- /*
- * No more threads holding lock, we can do the actual hardware
- * release
- */
- ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_common_fACS.global_lock, pending);
acpi_gbl_global_lock_acquired = FALSE;
- /*
- * 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_MTX_LOCK);
- }
+ /* Release the local GL mutex */
+ acpi_os_release_mutex(acpi_gbl_global_lock_mutex);
return_ACPI_STATUS(status);
}
git.samba.org / sfrench / cifs-2.6.git / blobdiff