summaryrefslogtreecommitdiffstats
path: root/drivers/acpi/acpica/evglock.c
blob: 9aab54797ded929449505222ca0510b1dabd2419 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/******************************************************************************
 *
 * Module Name: evglock - Global Lock support
 *
 * Copyright (C) 2000 - 2022, Intel Corp.
 *
 *****************************************************************************/

#include <acpi/acpi.h>
#include "accommon.h"
#include "acevents.h"
#include "acinterp.h"

#define _COMPONENT          ACPI_EVENTS
ACPI_MODULE_NAME("evglock")
#if (!ACPI_REDUCED_HARDWARE)	/* Entire module */
/* Local prototypes */
static u32 acpi_ev_global_lock_handler(void *context);

/*******************************************************************************
 *
 * FUNCTION:    acpi_ev_init_global_lock_handler
 *
 * PARAMETERS:  None
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Install a handler for the global lock release event
 *
 ******************************************************************************/

acpi_status acpi_ev_init_global_lock_handler(void)
{
	acpi_status status;

	ACPI_FUNCTION_TRACE(ev_init_global_lock_handler);

	/* If Hardware Reduced flag is set, there is no global lock */

	if (acpi_gbl_reduced_hardware) {
		return_ACPI_STATUS(AE_OK);
	}

	/* Attempt installation of the global lock handler */

	status = acpi_install_fixed_event_handler(ACPI_EVENT_GLOBAL,
						  acpi_ev_global_lock_handler,
						  NULL);

	/*
	 * If the global lock does not exist on this platform, the attempt to
	 * enable GBL_STATUS will fail (the GBL_ENABLE bit will not stick).
	 * Map to AE_OK, but mark global lock as not present. Any attempt to
	 * actually use the global lock will be flagged with an error.
	 */
	acpi_gbl_global_lock_present = FALSE;
	if (status == AE_NO_HARDWARE_RESPONSE) {
		ACPI_ERROR((AE_INFO,
			    "No response from Global Lock hardware, disabling lock"));

		return_ACPI_STATUS(AE_OK);
	}

	status = acpi_os_create_lock(&acpi_gbl_global_lock_pending_lock);
	if (ACPI_FAILURE(status)) {
		return_ACPI_STATUS(status);
	}

	acpi_gbl_global_lock_pending = FALSE;
	acpi_gbl_global_lock_present = TRUE;
	return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ev_remove_global_lock_handler
 *
 * PARAMETERS:  None
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Remove the handler for the Global Lock
 *
 ******************************************************************************/

acpi_status acpi_ev_remove_global_lock_handler(void)
{
	acpi_status status;

	ACPI_FUNCTION_TRACE(ev_remove_global_lock_handler);

	acpi_gbl_global_lock_present = FALSE;
	status = acpi_remove_fixed_event_handler(ACPI_EVENT_GLOBAL,
						 acpi_ev_global_lock_handler);

	acpi_os_delete_lock(acpi_gbl_global_lock_pending_lock);
	return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ev_global_lock_handler
 *
 * PARAMETERS:  context         - From thread interface, not used
 *
 * RETURN:      ACPI_INTERRUPT_HANDLED
 *
 * DESCRIPTION: Invoked directly from the SCI handler when a global lock
 *              release interrupt occurs. If there is actually a pending
 *              request for the lock, signal the waiting thread.
 *
 ******************************************************************************/

static u32 acpi_ev_global_lock_handler(void *context)
{
	acpi_status status;
	acpi_cpu_flags flags;

	flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);

	/*
	 * If a request for the global lock is not actually pending,
	 * we are done. This handles "spurious" global lock interrupts
	 * which are possible (and have been seen) with bad BIOSs.
	 */
	if (!acpi_gbl_global_lock_pending) {
		goto cleanup_and_exit;
	}

	/*
	 * Send a unit to the global lock semaphore. The actual acquisition
	 * of the global lock will be performed by the waiting thread.
	 */
	status = acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore, 1);
	if (ACPI_FAILURE(status)) {
		ACPI_ERROR((AE_INFO, "Could not signal Global Lock semaphore"));
	}

	acpi_gbl_global_lock_pending = FALSE;

cleanup_and_exit:

	acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);
	return (ACPI_INTERRUPT_HANDLED);
}

/******************************************************************************
 *
 * FUNCTION:    acpi_ev_acquire_global_lock
 *
 * PARAMETERS:  timeout         - Max time to wait for the lock, in millisec.
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Attempt to gain ownership of the Global Lock.
 *
 * MUTEX:       Interpreter must be locked
 *
 * Note: The original implementation allowed multiple threads to "acquire" the
 * Global Lock, and the OS would hold the lock until the last thread had
 * released it. However, this could potentially starve the BIOS out of the
 * lock, especially in the case where there is a tight handshake between the
 * Embedded Controller driver and the BIOS. Therefore, this implementation
 * allows only one thread to acquire the HW Global Lock at a time, and makes
 * the global lock appear as a standard mutex on the OS side.
 *
 *****************************************************************************/

acpi_status acpi_ev_acquire_global_lock(u16 timeout)
{
	acpi_cpu_flags flags;
	acpi_status status;
	u8 acquired = FALSE;

	ACPI_FUNCTION_TRACE(ev_acquire_global_lock);

	/*
	 * Only one thread can acquire the GL at a time, the global_lock_mutex
	 * enforces this. This interface releases the interpreter if we must wait.
	 */
	status =
	    acpi_ex_system_wait_mutex(acpi_gbl_global_lock_mutex->mutex.
				      os_mutex, timeout);
	if (ACPI_FAILURE(status)) {
		return_ACPI_STATUS(status);
	}

	/*
	 * Update the global lock handle and check for wraparound. The handle is
	 * only used for the external global lock interfaces, but it is updated
	 * here to properly handle the case where a single thread may acquire the
	 * lock via both the AML and the acpi_acquire_global_lock interfaces. The
	 * handle is therefore updated on the first acquire from a given thread
	 * regardless of where the acquisition request originated.
	 */
	acpi_gbl_global_lock_handle++;
	if (acpi_gbl_global_lock_handle == 0) {
		acpi_gbl_global_lock_handle = 1;
	}

	/*
	 * Make sure that a global lock actually exists. If not, just
	 * treat the lock as a standard mutex.
	 */
	if (!acpi_gbl_global_lock_present) {
		acpi_gbl_global_lock_acquired = TRUE;
		return_ACPI_STATUS(AE_OK);
	}

	flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);

	do {

		/* Attempt to acquire the actual hardware lock */

		ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_FACS, acquired);
		if (acquired) {
			acpi_gbl_global_lock_acquired = TRUE;
			ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
					  "Acquired hardware Global Lock\n"));
			break;
		}

		/*
		 * Did not get the lock. The pending bit was set above, and
		 * we must now wait until we receive the global lock
		 * released interrupt.
		 */
		acpi_gbl_global_lock_pending = TRUE;
		acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);

		ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
				  "Waiting for hardware Global Lock\n"));

		/*
		 * Wait for handshake with the global lock interrupt handler.
		 * This interface releases the interpreter if we must wait.
		 */
		status =
		    acpi_ex_system_wait_semaphore
		    (acpi_gbl_global_lock_semaphore, ACPI_WAIT_FOREVER);

		flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock);

	} while (ACPI_SUCCESS(status));

	acpi_gbl_global_lock_pending = FALSE;
	acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags);

	return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ev_release_global_lock
 *
 * PARAMETERS:  None
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Releases ownership of the Global Lock.
 *
 ******************************************************************************/

acpi_status acpi_ev_release_global_lock(void)
{
	u8 pending = FALSE;
	acpi_status status = AE_OK;

	ACPI_FUNCTION_TRACE(ev_release_global_lock);

	/* Lock must be already acquired */

	if (!acpi_gbl_global_lock_acquired) {
		ACPI_WARNING((AE_INFO,
			      "Cannot release the ACPI Global Lock, it has not been acquired"));
		return_ACPI_STATUS(AE_NOT_ACQUIRED);
	}

	if (acpi_gbl_global_lock_present) {

		/* Allow any thread to release the lock */

		ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_FACS, pending);

		/*
		 * If the pending bit was set, we must write GBL_RLS to the control
		 * register
		 */
		if (pending) {
			status =
			    acpi_write_bit_register
			    (ACPI_BITREG_GLOBAL_LOCK_RELEASE,
			     ACPI_ENABLE_EVENT);
		}

		ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
				  "Released hardware Global Lock\n"));
	}

	acpi_gbl_global_lock_acquired = FALSE;

	/* Release the local GL mutex */

	acpi_os_release_mutex(acpi_gbl_global_lock_mutex->mutex.os_mutex);
	return_ACPI_STATUS(status);
}

#endif				/* !ACPI_REDUCED_HARDWARE */