Revert "ARM: tegra: tegratab: dummy change"
[linux-2.6.git] / drivers / acpi / acpica / evglock.c
1 /******************************************************************************
2  *
3  * Module Name: evglock - Global Lock support
4  *
5  *****************************************************************************/
6
7 /*
8  * Copyright (C) 2000 - 2012, Intel Corp.
9  * All rights reserved.
10  *
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.
25  *
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.
29  *
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.
42  */
43
44 #include <acpi/acpi.h>
45 #include "accommon.h"
46 #include "acevents.h"
47 #include "acinterp.h"
48
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);
54
55 /*******************************************************************************
56  *
57  * FUNCTION:    acpi_ev_init_global_lock_handler
58  *
59  * PARAMETERS:  None
60  *
61  * RETURN:      Status
62  *
63  * DESCRIPTION: Install a handler for the global lock release event
64  *
65  ******************************************************************************/
66
67 acpi_status acpi_ev_init_global_lock_handler(void)
68 {
69         acpi_status status;
70
71         ACPI_FUNCTION_TRACE(ev_init_global_lock_handler);
72
73         /* If Hardware Reduced flag is set, there is no global lock */
74
75         if (acpi_gbl_reduced_hardware) {
76                 return_ACPI_STATUS(AE_OK);
77         }
78
79         /* Attempt installation of the global lock handler */
80
81         status = acpi_install_fixed_event_handler(ACPI_EVENT_GLOBAL,
82                                                   acpi_ev_global_lock_handler,
83                                                   NULL);
84
85         /*
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.
90          */
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"));
95
96                 return_ACPI_STATUS(AE_OK);
97         }
98
99         status = acpi_os_create_lock(&acpi_gbl_global_lock_pending_lock);
100         if (ACPI_FAILURE(status)) {
101                 return_ACPI_STATUS(status);
102         }
103
104         acpi_gbl_global_lock_pending = FALSE;
105         acpi_gbl_global_lock_present = TRUE;
106         return_ACPI_STATUS(status);
107 }
108
109 /*******************************************************************************
110  *
111  * FUNCTION:    acpi_ev_remove_global_lock_handler
112  *
113  * PARAMETERS:  None
114  *
115  * RETURN:      Status
116  *
117  * DESCRIPTION: Remove the handler for the Global Lock
118  *
119  ******************************************************************************/
120
121 acpi_status acpi_ev_remove_global_lock_handler(void)
122 {
123         acpi_status status;
124
125         ACPI_FUNCTION_TRACE(ev_remove_global_lock_handler);
126
127         acpi_gbl_global_lock_present = FALSE;
128         status = acpi_remove_fixed_event_handler(ACPI_EVENT_GLOBAL,
129                                                  acpi_ev_global_lock_handler);
130
131         return_ACPI_STATUS(status);
132 }
133
134 /*******************************************************************************
135  *
136  * FUNCTION:    acpi_ev_global_lock_handler
137  *
138  * PARAMETERS:  Context         - From thread interface, not used
139  *
140  * RETURN:      ACPI_INTERRUPT_HANDLED
141  *
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.
145  *
146  ******************************************************************************/
147
148 static u32 acpi_ev_global_lock_handler(void *context)
149 {
150         acpi_status status;
151         acpi_cpu_flags flags;
152
153         flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
154
155         /*
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.
159          */
160         if (!acpi_gbl_global_lock_pending) {
161                 goto cleanup_and_exit;
162         }
163
164         /*
165          * Send a unit to the global lock semaphore. The actual acquisition
166          * of the global lock will be performed by the waiting thread.
167          */
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"));
171         }
172
173         acpi_gbl_global_lock_pending = FALSE;
174
175       cleanup_and_exit:
176
177         acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
178         return (ACPI_INTERRUPT_HANDLED);
179 }
180
181 /******************************************************************************
182  *
183  * FUNCTION:    acpi_ev_acquire_global_lock
184  *
185  * PARAMETERS:  Timeout         - Max time to wait for the lock, in millisec.
186  *
187  * RETURN:      Status
188  *
189  * DESCRIPTION: Attempt to gain ownership of the Global Lock.
190  *
191  * MUTEX:       Interpreter must be locked
192  *
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.
200  *
201  *****************************************************************************/
202
203 acpi_status acpi_ev_acquire_global_lock(u16 timeout)
204 {
205         acpi_cpu_flags flags;
206         acpi_status status;
207         u8 acquired = FALSE;
208
209         ACPI_FUNCTION_TRACE(ev_acquire_global_lock);
210
211         /*
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.
214          */
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);
220         }
221
222         /*
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.
229          */
230         acpi_gbl_global_lock_handle++;
231         if (acpi_gbl_global_lock_handle == 0) {
232                 acpi_gbl_global_lock_handle = 1;
233         }
234
235         /*
236          * Make sure that a global lock actually exists. If not, just
237          * treat the lock as a standard mutex.
238          */
239         if (!acpi_gbl_global_lock_present) {
240                 acpi_gbl_global_lock_acquired = TRUE;
241                 return_ACPI_STATUS(AE_OK);
242         }
243
244         flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
245
246         do {
247
248                 /* Attempt to acquire the actual hardware lock */
249
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;
256                 }
257
258                 /*
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.
262                  */
263                 acpi_gbl_global_lock_pending = TRUE;
264                 acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
265
266                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
267                                   "Waiting for hardware Global Lock\n"));
268
269                 /*
270                  * Wait for handshake with the global lock interrupt handler.
271                  * This interface releases the interpreter if we must wait.
272                  */
273                 status =
274                     acpi_ex_system_wait_semaphore
275                     (acpi_gbl_global_lock_semaphore, ACPI_WAIT_FOREVER);
276
277                 flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);
278
279         } while (ACPI_SUCCESS(status));
280
281         acpi_gbl_global_lock_pending = FALSE;
282         acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
283
284         return_ACPI_STATUS(status);
285 }
286
287 /*******************************************************************************
288  *
289  * FUNCTION:    acpi_ev_release_global_lock
290  *
291  * PARAMETERS:  None
292  *
293  * RETURN:      Status
294  *
295  * DESCRIPTION: Releases ownership of the Global Lock.
296  *
297  ******************************************************************************/
298
299 acpi_status acpi_ev_release_global_lock(void)
300 {
301         u8 pending = FALSE;
302         acpi_status status = AE_OK;
303
304         ACPI_FUNCTION_TRACE(ev_release_global_lock);
305
306         /* Lock must be already acquired */
307
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);
312         }
313
314         if (acpi_gbl_global_lock_present) {
315
316                 /* Allow any thread to release the lock */
317
318                 ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_FACS, pending);
319
320                 /*
321                  * If the pending bit was set, we must write GBL_RLS to the control
322                  * register
323                  */
324                 if (pending) {
325                         status =
326                             acpi_write_bit_register
327                             (ACPI_BITREG_GLOBAL_LOCK_RELEASE,
328                              ACPI_ENABLE_EVENT);
329                 }
330
331                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
332                                   "Released hardware Global Lock\n"));
333         }
334
335         acpi_gbl_global_lock_acquired = FALSE;
336
337         /* Release the local GL mutex */
338
339         acpi_os_release_mutex(acpi_gbl_global_lock_mutex->mutex.os_mutex);
340         return_ACPI_STATUS(status);
341 }
342
343 #endif                          /* !ACPI_REDUCED_HARDWARE */