1 /******************************************************************************
3 * Module Name: evglock - Global Lock support
5 *****************************************************************************/
8 * Copyright (C) 2000 - 2015, Intel Corp.
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12 * modification, are permitted provided that the following conditions
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20 * including a substantially similar Disclaimer requirement for further
21 * binary redistribution.
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23 * of any contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
26 * Alternatively, this software may be distributed under the terms of the
27 * GNU General Public License ("GPL") version 2 as published by the Free
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44 #include <acpi/acpi.h>
49 #define _COMPONENT ACPI_EVENTS
50 ACPI_MODULE_NAME("evglock")
51 #if (!ACPI_REDUCED_HARDWARE) /* Entire module */
52 /* Local prototypes */
53 static u32
acpi_ev_global_lock_handler(void *context
);
55 /*******************************************************************************
57 * FUNCTION: acpi_ev_init_global_lock_handler
63 * DESCRIPTION: Install a handler for the global lock release event
65 ******************************************************************************/
67 acpi_status
acpi_ev_init_global_lock_handler(void)
71 ACPI_FUNCTION_TRACE(ev_init_global_lock_handler
);
73 /* If Hardware Reduced flag is set, there is no global lock */
75 if (acpi_gbl_reduced_hardware
) {
76 return_ACPI_STATUS(AE_OK
);
79 /* Attempt installation of the global lock handler */
81 status
= acpi_install_fixed_event_handler(ACPI_EVENT_GLOBAL
,
82 acpi_ev_global_lock_handler
,
86 * If the global lock does not exist on this platform, the attempt to
87 * enable GBL_STATUS will fail (the GBL_ENABLE bit will not stick).
88 * Map to AE_OK, but mark global lock as not present. Any attempt to
89 * actually use the global lock will be flagged with an error.
91 acpi_gbl_global_lock_present
= FALSE
;
92 if (status
== AE_NO_HARDWARE_RESPONSE
) {
94 "No response from Global Lock hardware, disabling lock"));
96 return_ACPI_STATUS(AE_OK
);
99 status
= acpi_os_create_lock(&acpi_gbl_global_lock_pending_lock
);
100 if (ACPI_FAILURE(status
)) {
101 return_ACPI_STATUS(status
);
104 acpi_gbl_global_lock_pending
= FALSE
;
105 acpi_gbl_global_lock_present
= TRUE
;
106 return_ACPI_STATUS(status
);
109 /*******************************************************************************
111 * FUNCTION: acpi_ev_remove_global_lock_handler
117 * DESCRIPTION: Remove the handler for the Global Lock
119 ******************************************************************************/
121 acpi_status
acpi_ev_remove_global_lock_handler(void)
125 ACPI_FUNCTION_TRACE(ev_remove_global_lock_handler
);
127 acpi_gbl_global_lock_present
= FALSE
;
128 status
= acpi_remove_fixed_event_handler(ACPI_EVENT_GLOBAL
,
129 acpi_ev_global_lock_handler
);
131 acpi_os_delete_lock(acpi_gbl_global_lock_pending_lock
);
132 return_ACPI_STATUS(status
);
135 /*******************************************************************************
137 * FUNCTION: acpi_ev_global_lock_handler
139 * PARAMETERS: context - From thread interface, not used
141 * RETURN: ACPI_INTERRUPT_HANDLED
143 * DESCRIPTION: Invoked directly from the SCI handler when a global lock
144 * release interrupt occurs. If there is actually a pending
145 * request for the lock, signal the waiting thread.
147 ******************************************************************************/
149 static u32
acpi_ev_global_lock_handler(void *context
)
152 acpi_cpu_flags flags
;
154 flags
= acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock
);
157 * If a request for the global lock is not actually pending,
158 * we are done. This handles "spurious" global lock interrupts
159 * which are possible (and have been seen) with bad BIOSs.
161 if (!acpi_gbl_global_lock_pending
) {
162 goto cleanup_and_exit
;
166 * Send a unit to the global lock semaphore. The actual acquisition
167 * of the global lock will be performed by the waiting thread.
169 status
= acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore
, 1);
170 if (ACPI_FAILURE(status
)) {
171 ACPI_ERROR((AE_INFO
, "Could not signal Global Lock semaphore"));
174 acpi_gbl_global_lock_pending
= FALSE
;
178 acpi_os_release_lock(acpi_gbl_global_lock_pending_lock
, flags
);
179 return (ACPI_INTERRUPT_HANDLED
);
182 /******************************************************************************
184 * FUNCTION: acpi_ev_acquire_global_lock
186 * PARAMETERS: timeout - Max time to wait for the lock, in millisec.
190 * DESCRIPTION: Attempt to gain ownership of the Global Lock.
192 * MUTEX: Interpreter must be locked
194 * Note: The original implementation allowed multiple threads to "acquire" the
195 * Global Lock, and the OS would hold the lock until the last thread had
196 * released it. However, this could potentially starve the BIOS out of the
197 * lock, especially in the case where there is a tight handshake between the
198 * Embedded Controller driver and the BIOS. Therefore, this implementation
199 * allows only one thread to acquire the HW Global Lock at a time, and makes
200 * the global lock appear as a standard mutex on the OS side.
202 *****************************************************************************/
204 acpi_status
acpi_ev_acquire_global_lock(u16 timeout
)
206 acpi_cpu_flags flags
;
210 ACPI_FUNCTION_TRACE(ev_acquire_global_lock
);
213 * Only one thread can acquire the GL at a time, the global_lock_mutex
214 * enforces this. This interface releases the interpreter if we must wait.
217 acpi_ex_system_wait_mutex(acpi_gbl_global_lock_mutex
->mutex
.
219 if (ACPI_FAILURE(status
)) {
220 return_ACPI_STATUS(status
);
224 * Update the global lock handle and check for wraparound. The handle is
225 * only used for the external global lock interfaces, but it is updated
226 * here to properly handle the case where a single thread may acquire the
227 * lock via both the AML and the acpi_acquire_global_lock interfaces. The
228 * handle is therefore updated on the first acquire from a given thread
229 * regardless of where the acquisition request originated.
231 acpi_gbl_global_lock_handle
++;
232 if (acpi_gbl_global_lock_handle
== 0) {
233 acpi_gbl_global_lock_handle
= 1;
237 * Make sure that a global lock actually exists. If not, just
238 * treat the lock as a standard mutex.
240 if (!acpi_gbl_global_lock_present
) {
241 acpi_gbl_global_lock_acquired
= TRUE
;
242 return_ACPI_STATUS(AE_OK
);
245 flags
= acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock
);
249 /* Attempt to acquire the actual hardware lock */
251 ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_FACS
, acquired
);
253 acpi_gbl_global_lock_acquired
= TRUE
;
254 ACPI_DEBUG_PRINT((ACPI_DB_EXEC
,
255 "Acquired hardware Global Lock\n"));
260 * Did not get the lock. The pending bit was set above, and
261 * we must now wait until we receive the global lock
262 * released interrupt.
264 acpi_gbl_global_lock_pending
= TRUE
;
265 acpi_os_release_lock(acpi_gbl_global_lock_pending_lock
, flags
);
267 ACPI_DEBUG_PRINT((ACPI_DB_EXEC
,
268 "Waiting for hardware Global Lock\n"));
271 * Wait for handshake with the global lock interrupt handler.
272 * This interface releases the interpreter if we must wait.
275 acpi_ex_system_wait_semaphore
276 (acpi_gbl_global_lock_semaphore
, ACPI_WAIT_FOREVER
);
278 flags
= acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock
);
280 } while (ACPI_SUCCESS(status
));
282 acpi_gbl_global_lock_pending
= FALSE
;
283 acpi_os_release_lock(acpi_gbl_global_lock_pending_lock
, flags
);
285 return_ACPI_STATUS(status
);
288 /*******************************************************************************
290 * FUNCTION: acpi_ev_release_global_lock
296 * DESCRIPTION: Releases ownership of the Global Lock.
298 ******************************************************************************/
300 acpi_status
acpi_ev_release_global_lock(void)
303 acpi_status status
= AE_OK
;
305 ACPI_FUNCTION_TRACE(ev_release_global_lock
);
307 /* Lock must be already acquired */
309 if (!acpi_gbl_global_lock_acquired
) {
310 ACPI_WARNING((AE_INFO
,
311 "Cannot release the ACPI Global Lock, it has not been acquired"));
312 return_ACPI_STATUS(AE_NOT_ACQUIRED
);
315 if (acpi_gbl_global_lock_present
) {
317 /* Allow any thread to release the lock */
319 ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_FACS
, pending
);
322 * If the pending bit was set, we must write GBL_RLS to the control
327 acpi_write_bit_register
328 (ACPI_BITREG_GLOBAL_LOCK_RELEASE
,
332 ACPI_DEBUG_PRINT((ACPI_DB_EXEC
,
333 "Released hardware Global Lock\n"));
336 acpi_gbl_global_lock_acquired
= FALSE
;
338 /* Release the local GL mutex */
340 acpi_os_release_mutex(acpi_gbl_global_lock_mutex
->mutex
.os_mutex
);
341 return_ACPI_STATUS(status
);
344 #endif /* !ACPI_REDUCED_HARDWARE */