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[pohmelfs.git] / drivers / acpi / acpica / evglock.c
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1 /******************************************************************************
3 * Module Name: evglock - Global Lock support
5 *****************************************************************************/
7 /*
8 * Copyright (C) 2000 - 2012, Intel Corp.
9 * All rights reserved.
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions, and the following disclaimer,
16 * without modification.
17 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
18 * substantially similar to the "NO WARRANTY" disclaimer below
19 * ("Disclaimer") and any redistribution must be conditioned upon
20 * including a substantially similar Disclaimer requirement for further
21 * binary redistribution.
22 * 3. Neither the names of the above-listed copyright holders nor the names
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
28 * Software Foundation.
30 * NO WARRANTY
31 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
32 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
33 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
34 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
35 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
40 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
41 * POSSIBILITY OF SUCH DAMAGES.
44 #include <acpi/acpi.h>
45 #include "accommon.h"
46 #include "acevents.h"
47 #include "acinterp.h"
49 #define _COMPONENT ACPI_EVENTS
50 ACPI_MODULE_NAME("evglock")
52 /* Local prototypes */
53 static u32 acpi_ev_global_lock_handler(void *context);
55 /*******************************************************************************
57 * FUNCTION: acpi_ev_init_global_lock_handler
59 * PARAMETERS: None
61 * RETURN: Status
63 * DESCRIPTION: Install a handler for the global lock release event
65 ******************************************************************************/
67 acpi_status acpi_ev_init_global_lock_handler(void)
69 acpi_status status;
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,
83 NULL);
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) {
93 ACPI_ERROR((AE_INFO,
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
113 * PARAMETERS: None
115 * RETURN: Status
117 * DESCRIPTION: Remove the handler for the Global Lock
119 ******************************************************************************/
121 acpi_status acpi_ev_remove_global_lock_handler(void)
123 acpi_status status;
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 return_ACPI_STATUS(status);
134 /*******************************************************************************
136 * FUNCTION: acpi_ev_global_lock_handler
138 * PARAMETERS: Context - From thread interface, not used
140 * RETURN: ACPI_INTERRUPT_HANDLED
142 * DESCRIPTION: Invoked directly from the SCI handler when a global lock
143 * release interrupt occurs. If there is actually a pending
144 * request for the lock, signal the waiting thread.
146 ******************************************************************************/
148 static u32 acpi_ev_global_lock_handler(void *context)
150 acpi_status status;
151 acpi_cpu_flags flags;
153 flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
156 * If a request for the global lock is not actually pending,
157 * we are done. This handles "spurious" global lock interrupts
158 * which are possible (and have been seen) with bad BIOSs.
160 if (!acpi_gbl_global_lock_pending) {
161 goto cleanup_and_exit;
165 * Send a unit to the global lock semaphore. The actual acquisition
166 * of the global lock will be performed by the waiting thread.
168 status = acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore, 1);
169 if (ACPI_FAILURE(status)) {
170 ACPI_ERROR((AE_INFO, "Could not signal Global Lock semaphore"));
173 acpi_gbl_global_lock_pending = FALSE;
175 cleanup_and_exit:
177 acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
178 return (ACPI_INTERRUPT_HANDLED);
181 /******************************************************************************
183 * FUNCTION: acpi_ev_acquire_global_lock
185 * PARAMETERS: Timeout - Max time to wait for the lock, in millisec.
187 * RETURN: Status
189 * DESCRIPTION: Attempt to gain ownership of the Global Lock.
191 * MUTEX: Interpreter must be locked
193 * Note: The original implementation allowed multiple threads to "acquire" the
194 * Global Lock, and the OS would hold the lock until the last thread had
195 * released it. However, this could potentially starve the BIOS out of the
196 * lock, especially in the case where there is a tight handshake between the
197 * Embedded Controller driver and the BIOS. Therefore, this implementation
198 * allows only one thread to acquire the HW Global Lock at a time, and makes
199 * the global lock appear as a standard mutex on the OS side.
201 *****************************************************************************/
203 acpi_status acpi_ev_acquire_global_lock(u16 timeout)
205 acpi_cpu_flags flags;
206 acpi_status status;
207 u8 acquired = FALSE;
209 ACPI_FUNCTION_TRACE(ev_acquire_global_lock);
212 * Only one thread can acquire the GL at a time, the global_lock_mutex
213 * enforces this. This interface releases the interpreter if we must wait.
215 status =
216 acpi_ex_system_wait_mutex(acpi_gbl_global_lock_mutex->mutex.
217 os_mutex, timeout);
218 if (ACPI_FAILURE(status)) {
219 return_ACPI_STATUS(status);
223 * Update the global lock handle and check for wraparound. The handle is
224 * only used for the external global lock interfaces, but it is updated
225 * here to properly handle the case where a single thread may acquire the
226 * lock via both the AML and the acpi_acquire_global_lock interfaces. The
227 * handle is therefore updated on the first acquire from a given thread
228 * regardless of where the acquisition request originated.
230 acpi_gbl_global_lock_handle++;
231 if (acpi_gbl_global_lock_handle == 0) {
232 acpi_gbl_global_lock_handle = 1;
236 * Make sure that a global lock actually exists. If not, just
237 * treat the lock as a standard mutex.
239 if (!acpi_gbl_global_lock_present) {
240 acpi_gbl_global_lock_acquired = TRUE;
241 return_ACPI_STATUS(AE_OK);
244 flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
246 do {
248 /* Attempt to acquire the actual hardware lock */
250 ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_FACS, acquired);
251 if (acquired) {
252 acpi_gbl_global_lock_acquired = TRUE;
253 ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
254 "Acquired hardware Global Lock\n"));
255 break;
259 * Did not get the lock. The pending bit was set above, and
260 * we must now wait until we receive the global lock
261 * released interrupt.
263 acpi_gbl_global_lock_pending = TRUE;
264 acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
266 ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
267 "Waiting for hardware Global Lock\n"));
270 * Wait for handshake with the global lock interrupt handler.
271 * This interface releases the interpreter if we must wait.
273 status =
274 acpi_ex_system_wait_semaphore
275 (acpi_gbl_global_lock_semaphore, ACPI_WAIT_FOREVER);
277 flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
279 } while (ACPI_SUCCESS(status));
281 acpi_gbl_global_lock_pending = FALSE;
282 acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
284 return_ACPI_STATUS(status);
287 /*******************************************************************************
289 * FUNCTION: acpi_ev_release_global_lock
291 * PARAMETERS: None
293 * RETURN: Status
295 * DESCRIPTION: Releases ownership of the Global Lock.
297 ******************************************************************************/
299 acpi_status acpi_ev_release_global_lock(void)
301 u8 pending = FALSE;
302 acpi_status status = AE_OK;
304 ACPI_FUNCTION_TRACE(ev_release_global_lock);
306 /* Lock must be already acquired */
308 if (!acpi_gbl_global_lock_acquired) {
309 ACPI_WARNING((AE_INFO,
310 "Cannot release the ACPI Global Lock, it has not been acquired"));
311 return_ACPI_STATUS(AE_NOT_ACQUIRED);
314 if (acpi_gbl_global_lock_present) {
316 /* Allow any thread to release the lock */
318 ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_FACS, pending);
321 * If the pending bit was set, we must write GBL_RLS to the control
322 * register
324 if (pending) {
325 status =
326 acpi_write_bit_register
327 (ACPI_BITREG_GLOBAL_LOCK_RELEASE,
328 ACPI_ENABLE_EVENT);
331 ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
332 "Released hardware Global Lock\n"));
335 acpi_gbl_global_lock_acquired = FALSE;
337 /* Release the local GL mutex */
339 acpi_os_release_mutex(acpi_gbl_global_lock_mutex->mutex.os_mutex);
340 return_ACPI_STATUS(status);