1 files changed, 115 insertions, 86 deletions

diff --git a/drivers/acpi/events/evmisc.c b/drivers/acpi/events/evmisc.c
index bf63edc6608d..1b784ffe54c3 100644
--- a/drivers/acpi/events/evmisc.c
+++ b/drivers/acpi/events/evmisc.c
@@ -5,7 +5,7 @@
  *****************************************************************************/
 
 /*
- * Copyright (C) 2000 - 2006, R. Byron Moore
+ * Copyright (C) 2000 - 2007, R. Byron Moore
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -63,14 +63,18 @@ static const char *acpi_notify_value_names[] = {
 };
 #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);
 
+static acpi_status acpi_ev_remove_global_lock_handler(void);
+
 /*******************************************************************************
  *
  * FUNCTION:    acpi_ev_is_notify_object
@@ -282,49 +286,19 @@ static void ACPI_SYSTEM_XFACE acpi_ev_notify_dispatch(void *context)
 
 /*******************************************************************************
  *
- * 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.
  *
  ******************************************************************************/
 
@@ -333,16 +307,24 @@ static u32 acpi_ev_global_lock_handler(void *context)
         u8 acquired = FALSE;
 
         /*
-         * 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);
@@ -366,6 +348,13 @@ acpi_status acpi_ev_init_global_lock_handler(void)
 
         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,
@@ -389,6 +378,31 @@ acpi_status acpi_ev_init_global_lock_handler(void)
         return_ACPI_STATUS(status);
 }
 
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ev_remove_global_lock_handler
+ *
+ * PARAMETERS:  None
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Remove the handler for the Global Lock
+ *
+ ******************************************************************************/
+
+static 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);
+
+        return_ACPI_STATUS(status);
+}
+
 /******************************************************************************
  *
  * FUNCTION:    acpi_ev_acquire_global_lock
@@ -399,6 +413,16 @@ acpi_status acpi_ev_init_global_lock_handler(void)
  *
  * 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)
@@ -408,53 +432,51 @@ 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);
 }
 
@@ -477,38 +499,39 @@ acpi_status acpi_ev_release_global_lock(void)
 
         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);
 }
 
@@ -558,6 +581,12 @@ void acpi_ev_terminate(void)
                 if (ACPI_FAILURE(status)) {
                         ACPI_ERROR((AE_INFO, "Could not remove SCI handler"));
                 }
+
+                status = acpi_ev_remove_global_lock_handler();
+                if (ACPI_FAILURE(status)) {
+                        ACPI_ERROR((AE_INFO,
+                                    "Could not remove Global Lock handler"));
+                }
         }
 
         /* Deallocate all handler objects installed within GPE info structs */