evglock.c revision 306536 
1/******************************************************************************
2 *
3 * Module Name: evglock - Global Lock support
4 *
5 *****************************************************************************/
6
7/*
8 * Copyright (C) 2000 - 2016, 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 <contrib/dev/acpica/include/acpi.h>
45#include <contrib/dev/acpica/include/accommon.h>
46#include <contrib/dev/acpica/include/acevents.h>
47#include <contrib/dev/acpica/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
56static UINT32
57AcpiEvGlobalLockHandler (
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
73ACPI_STATUS
74AcpiEvInitGlobalLockHandler (
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
134ACPI_STATUS
135AcpiEvRemoveGlobalLockHandler (
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
167static UINT32
168AcpiEvGlobalLockHandler (
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
200CleanupAndExit:
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
229ACPI_STATUS
230AcpiEvAcquireGlobalLock (
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
332ACPI_STATUS
333AcpiEvReleaseGlobalLock (
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