evglock.c revision 25f044e64568dd83de34c16c837a96bbb2b0cecb 
1/******************************************************************************
2 *
3 * Module Name: evglock - Global Lock support
4 *
5 *****************************************************************************/
6
7/*
8 * Copyright (C) 2000 - 2013, 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
50ACPI_MODULE_NAME("evglock")
51#if (!ACPI_REDUCED_HARDWARE)	/* Entire module */
52/* Local prototypes */
53static 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
67acpi_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
121acpi_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
148static 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
203acpi_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
299acpi_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 */
344