1 /******************************************************************************
2  *
3  * Module Name: evglock - Global Lock support
4  *
5  *****************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2022, 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 MERCHANTABILITY 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.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 
52 #if (!ACPI_REDUCED_HARDWARE) /* Entire module */
53 
54 /* Local prototypes */
55 
56 static UINT32
57 AcpiEvGlobalLockHandler (
58     void                    *Context);
59 
60 
61 /*******************************************************************************
62  *
63  * FUNCTION:    AcpiEvInitGlobalLockHandler
64  *
65  * PARAMETERS:  None
66  *
67  * RETURN:      Status
68  *
69  * DESCRIPTION: Install a handler for the global lock release event
70  *
71  ******************************************************************************/
72 
73 ACPI_STATUS
AcpiEvInitGlobalLockHandler(void)74 AcpiEvInitGlobalLockHandler (
75     void)
76 {
77     ACPI_STATUS             Status;
78 
79 
80     ACPI_FUNCTION_TRACE (EvInitGlobalLockHandler);
81 
82 
83     /* If Hardware Reduced flag is set, there is no global lock */
84 
85     if (AcpiGbl_ReducedHardware)
86     {
87         return_ACPI_STATUS (AE_OK);
88     }
89 
90     /* Attempt installation of the global lock handler */
91 
92     Status = AcpiInstallFixedEventHandler (ACPI_EVENT_GLOBAL,
93         AcpiEvGlobalLockHandler, NULL);
94 
95     /*
96      * If the global lock does not exist on this platform, the attempt to
97      * enable GBL_STATUS will fail (the GBL_ENABLE bit will not stick).
98      * Map to AE_OK, but mark global lock as not present. Any attempt to
99      * actually use the global lock will be flagged with an error.
100      */
101     AcpiGbl_GlobalLockPresent = FALSE;
102     if (Status == AE_NO_HARDWARE_RESPONSE)
103     {
104         ACPI_ERROR ((AE_INFO,
105             "No response from Global Lock hardware, disabling lock"));
106 
107         return_ACPI_STATUS (AE_OK);
108     }
109 
110     Status = AcpiOsCreateLock (&AcpiGbl_GlobalLockPendingLock);
111     if (ACPI_FAILURE (Status))
112     {
113         return_ACPI_STATUS (Status);
114     }
115 
116     AcpiGbl_GlobalLockPending = FALSE;
117     AcpiGbl_GlobalLockPresent = TRUE;
118     return_ACPI_STATUS (Status);
119 }
120 
121 
122 /*******************************************************************************
123  *
124  * FUNCTION:    AcpiEvRemoveGlobalLockHandler
125  *
126  * PARAMETERS:  None
127  *
128  * RETURN:      Status
129  *
130  * DESCRIPTION: Remove the handler for the Global Lock
131  *
132  ******************************************************************************/
133 
134 ACPI_STATUS
AcpiEvRemoveGlobalLockHandler(void)135 AcpiEvRemoveGlobalLockHandler (
136     void)
137 {
138     ACPI_STATUS             Status;
139 
140 
141     ACPI_FUNCTION_TRACE (EvRemoveGlobalLockHandler);
142 
143 
144     AcpiGbl_GlobalLockPresent = FALSE;
145     Status = AcpiRemoveFixedEventHandler (ACPI_EVENT_GLOBAL,
146         AcpiEvGlobalLockHandler);
147 
148     AcpiOsDeleteLock (AcpiGbl_GlobalLockPendingLock);
149     return_ACPI_STATUS (Status);
150 }
151 
152 
153 /*******************************************************************************
154  *
155  * FUNCTION:    AcpiEvGlobalLockHandler
156  *
157  * PARAMETERS:  Context         - From thread interface, not used
158  *
159  * RETURN:      ACPI_INTERRUPT_HANDLED
160  *
161  * DESCRIPTION: Invoked directly from the SCI handler when a global lock
162  *              release interrupt occurs. If there is actually a pending
163  *              request for the lock, signal the waiting thread.
164  *
165  ******************************************************************************/
166 
167 static UINT32
AcpiEvGlobalLockHandler(void * Context)168 AcpiEvGlobalLockHandler (
169     void                    *Context)
170 {
171     ACPI_STATUS             Status;
172     ACPI_CPU_FLAGS          Flags;
173 
174 
175     Flags = AcpiOsAcquireLock (AcpiGbl_GlobalLockPendingLock);
176 
177     /*
178      * If a request for the global lock is not actually pending,
179      * we are done. This handles "spurious" global lock interrupts
180      * which are possible (and have been seen) with bad BIOSs.
181      */
182     if (!AcpiGbl_GlobalLockPending)
183     {
184         goto CleanupAndExit;
185     }
186 
187     /*
188      * Send a unit to the global lock semaphore. The actual acquisition
189      * of the global lock will be performed by the waiting thread.
190      */
191     Status = AcpiOsSignalSemaphore (AcpiGbl_GlobalLockSemaphore, 1);
192     if (ACPI_FAILURE (Status))
193     {
194         ACPI_ERROR ((AE_INFO, "Could not signal Global Lock semaphore"));
195     }
196 
197     AcpiGbl_GlobalLockPending = FALSE;
198 
199 
200 CleanupAndExit:
201 
202     AcpiOsReleaseLock (AcpiGbl_GlobalLockPendingLock, Flags);
203     return (ACPI_INTERRUPT_HANDLED);
204 }
205 
206 
207 /******************************************************************************
208  *
209  * FUNCTION:    AcpiEvAcquireGlobalLock
210  *
211  * PARAMETERS:  Timeout         - Max time to wait for the lock, in millisec.
212  *
213  * RETURN:      Status
214  *
215  * DESCRIPTION: Attempt to gain ownership of the Global Lock.
216  *
217  * MUTEX:       Interpreter must be locked
218  *
219  * Note: The original implementation allowed multiple threads to "acquire" the
220  * Global Lock, and the OS would hold the lock until the last thread had
221  * released it. However, this could potentially starve the BIOS out of the
222  * lock, especially in the case where there is a tight handshake between the
223  * Embedded Controller driver and the BIOS. Therefore, this implementation
224  * allows only one thread to acquire the HW Global Lock at a time, and makes
225  * the global lock appear as a standard mutex on the OS side.
226  *
227  *****************************************************************************/
228 
229 ACPI_STATUS
AcpiEvAcquireGlobalLock(UINT16 Timeout)230 AcpiEvAcquireGlobalLock (
231     UINT16                  Timeout)
232 {
233     ACPI_CPU_FLAGS          Flags;
234     ACPI_STATUS             Status;
235     BOOLEAN                 Acquired = FALSE;
236 
237 
238     ACPI_FUNCTION_TRACE (EvAcquireGlobalLock);
239 
240 
241     /*
242      * Only one thread can acquire the GL at a time, the GlobalLockMutex
243      * enforces this. This interface releases the interpreter if we must wait.
244      */
245     Status = AcpiExSystemWaitMutex (AcpiGbl_GlobalLockMutex->Mutex.OsMutex,
246                 Timeout);
247     if (ACPI_FAILURE (Status))
248     {
249         return_ACPI_STATUS (Status);
250     }
251 
252     /*
253      * Update the global lock handle and check for wraparound. The handle is
254      * only used for the external global lock interfaces, but it is updated
255      * here to properly handle the case where a single thread may acquire the
256      * lock via both the AML and the AcpiAcquireGlobalLock interfaces. The
257      * handle is therefore updated on the first acquire from a given thread
258      * regardless of where the acquisition request originated.
259      */
260     AcpiGbl_GlobalLockHandle++;
261     if (AcpiGbl_GlobalLockHandle == 0)
262     {
263         AcpiGbl_GlobalLockHandle = 1;
264     }
265 
266     /*
267      * Make sure that a global lock actually exists. If not, just
268      * treat the lock as a standard mutex.
269      */
270     if (!AcpiGbl_GlobalLockPresent)
271     {
272         AcpiGbl_GlobalLockAcquired = TRUE;
273         return_ACPI_STATUS (AE_OK);
274     }
275 
276     Flags = AcpiOsAcquireLock (AcpiGbl_GlobalLockPendingLock);
277 
278     do
279     {
280         /* Attempt to acquire the actual hardware lock */
281 
282         ACPI_ACQUIRE_GLOBAL_LOCK (AcpiGbl_FACS, Acquired);
283         if (Acquired)
284         {
285             AcpiGbl_GlobalLockAcquired = TRUE;
286             ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,
287                 "Acquired hardware Global Lock\n"));
288             break;
289         }
290 
291         /*
292          * Did not get the lock. The pending bit was set above, and
293          * we must now wait until we receive the global lock
294          * released interrupt.
295          */
296         AcpiGbl_GlobalLockPending = TRUE;
297         AcpiOsReleaseLock (AcpiGbl_GlobalLockPendingLock, Flags);
298 
299         ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,
300             "Waiting for hardware Global Lock\n"));
301 
302         /*
303          * Wait for handshake with the global lock interrupt handler.
304          * This interface releases the interpreter if we must wait.
305          */
306         Status = AcpiExSystemWaitSemaphore (
307             AcpiGbl_GlobalLockSemaphore, ACPI_WAIT_FOREVER);
308 
309         Flags = AcpiOsAcquireLock (AcpiGbl_GlobalLockPendingLock);
310 
311     } while (ACPI_SUCCESS (Status));
312 
313     AcpiGbl_GlobalLockPending = FALSE;
314     AcpiOsReleaseLock (AcpiGbl_GlobalLockPendingLock, Flags);
315 
316     return_ACPI_STATUS (Status);
317 }
318 
319 
320 /*******************************************************************************
321  *
322  * FUNCTION:    AcpiEvReleaseGlobalLock
323  *
324  * PARAMETERS:  None
325  *
326  * RETURN:      Status
327  *
328  * DESCRIPTION: Releases ownership of the Global Lock.
329  *
330  ******************************************************************************/
331 
332 ACPI_STATUS
AcpiEvReleaseGlobalLock(void)333 AcpiEvReleaseGlobalLock (
334     void)
335 {
336     BOOLEAN                 Pending = FALSE;
337     ACPI_STATUS             Status = AE_OK;
338 
339 
340     ACPI_FUNCTION_TRACE (EvReleaseGlobalLock);
341 
342 
343     /* Lock must be already acquired */
344 
345     if (!AcpiGbl_GlobalLockAcquired)
346     {
347         ACPI_WARNING ((AE_INFO,
348             "Cannot release the ACPI Global Lock, it has not been acquired"));
349         return_ACPI_STATUS (AE_NOT_ACQUIRED);
350     }
351 
352     if (AcpiGbl_GlobalLockPresent)
353     {
354         /* Allow any thread to release the lock */
355 
356         ACPI_RELEASE_GLOBAL_LOCK (AcpiGbl_FACS, Pending);
357 
358         /*
359          * If the pending bit was set, we must write GBL_RLS to the control
360          * register
361          */
362         if (Pending)
363         {
364             Status = AcpiWriteBitRegister (
365                 ACPI_BITREG_GLOBAL_LOCK_RELEASE, ACPI_ENABLE_EVENT);
366         }
367 
368         ACPI_DEBUG_PRINT ((ACPI_DB_EXEC, "Released hardware Global Lock\n"));
369     }
370 
371     AcpiGbl_GlobalLockAcquired = FALSE;
372 
373     /* Release the local GL mutex */
374 
375     AcpiOsReleaseMutex (AcpiGbl_GlobalLockMutex->Mutex.OsMutex);
376     return_ACPI_STATUS (Status);
377 }
378 
379 #endif /* !ACPI_REDUCED_HARDWARE */
380