diff options
Diffstat (limited to 'drivers/acpi/events')
| -rw-r--r-- | drivers/acpi/events/evmisc.c | 113 |
1 files changed, 59 insertions, 54 deletions
diff --git a/drivers/acpi/events/evmisc.c b/drivers/acpi/events/evmisc.c index bf63edc6608..f82b81cc183 100644 --- a/drivers/acpi/events/evmisc.c +++ b/drivers/acpi/events/evmisc.c @@ -298,19 +298,13 @@ static void ACPI_SYSTEM_XFACE acpi_ev_global_lock_thread(void *context) { acpi_status status; - /* Signal threads that are waiting for the lock */ + /* Signal the thread that is waiting for the lock */ - if (acpi_gbl_global_lock_thread_count) { + /* Send a unit to the semaphore */ - /* 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")); - } + 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")); } } @@ -333,7 +327,8 @@ 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. */ @@ -341,6 +336,7 @@ static u32 acpi_ev_global_lock_handler(void *context) if (acquired) { /* Got the lock, now wake all threads waiting for it */ + acpi_gbl_global_lock_acquired = TRUE; acpi_ev_global_lock_thread(context); } @@ -399,6 +395,16 @@ 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) @@ -408,27 +414,25 @@ 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); if (acquired) { @@ -436,25 +440,24 @@ acpi_status acpi_ev_acquire_global_lock(u16 timeout) /* 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 +480,40 @@ 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 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(acpi_gbl_common_fACS.global_lock, + 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_MTX_LOCK); + } + + 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); } |