1 | // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 |
2 | /****************************************************************************** |
3 | * |
4 | * Module Name: evglock - Global Lock support |
5 | * |
6 | * Copyright (C) 2000 - 2023, Intel Corp. |
7 | * |
8 | *****************************************************************************/ |
9 | |
10 | #include <acpi/acpi.h> |
11 | #include "accommon.h" |
12 | #include "acevents.h" |
13 | #include "acinterp.h" |
14 | |
15 | #define _COMPONENT ACPI_EVENTS |
16 | ACPI_MODULE_NAME("evglock" ) |
17 | #if (!ACPI_REDUCED_HARDWARE) /* Entire module */ |
18 | /* Local prototypes */ |
19 | static u32 acpi_ev_global_lock_handler(void *context); |
20 | |
21 | /******************************************************************************* |
22 | * |
23 | * FUNCTION: acpi_ev_init_global_lock_handler |
24 | * |
25 | * PARAMETERS: None |
26 | * |
27 | * RETURN: Status |
28 | * |
29 | * DESCRIPTION: Install a handler for the global lock release event |
30 | * |
31 | ******************************************************************************/ |
32 | |
33 | acpi_status acpi_ev_init_global_lock_handler(void) |
34 | { |
35 | acpi_status status; |
36 | |
37 | ACPI_FUNCTION_TRACE(ev_init_global_lock_handler); |
38 | |
39 | /* If Hardware Reduced flag is set, there is no global lock */ |
40 | |
41 | if (acpi_gbl_reduced_hardware) { |
42 | return_ACPI_STATUS(AE_OK); |
43 | } |
44 | |
45 | /* Attempt installation of the global lock handler */ |
46 | |
47 | status = acpi_install_fixed_event_handler(ACPI_EVENT_GLOBAL, |
48 | acpi_ev_global_lock_handler, |
49 | NULL); |
50 | |
51 | /* |
52 | * If the global lock does not exist on this platform, the attempt to |
53 | * enable GBL_STATUS will fail (the GBL_ENABLE bit will not stick). |
54 | * Map to AE_OK, but mark global lock as not present. Any attempt to |
55 | * actually use the global lock will be flagged with an error. |
56 | */ |
57 | acpi_gbl_global_lock_present = FALSE; |
58 | if (status == AE_NO_HARDWARE_RESPONSE) { |
59 | ACPI_ERROR((AE_INFO, |
60 | "No response from Global Lock hardware, disabling lock" )); |
61 | |
62 | return_ACPI_STATUS(AE_OK); |
63 | } |
64 | |
65 | status = acpi_os_create_lock(&acpi_gbl_global_lock_pending_lock); |
66 | if (ACPI_FAILURE(status)) { |
67 | return_ACPI_STATUS(status); |
68 | } |
69 | |
70 | acpi_gbl_global_lock_pending = FALSE; |
71 | acpi_gbl_global_lock_present = TRUE; |
72 | return_ACPI_STATUS(status); |
73 | } |
74 | |
75 | /******************************************************************************* |
76 | * |
77 | * FUNCTION: acpi_ev_remove_global_lock_handler |
78 | * |
79 | * PARAMETERS: None |
80 | * |
81 | * RETURN: Status |
82 | * |
83 | * DESCRIPTION: Remove the handler for the Global Lock |
84 | * |
85 | ******************************************************************************/ |
86 | |
87 | acpi_status acpi_ev_remove_global_lock_handler(void) |
88 | { |
89 | acpi_status status; |
90 | |
91 | ACPI_FUNCTION_TRACE(ev_remove_global_lock_handler); |
92 | |
93 | acpi_gbl_global_lock_present = FALSE; |
94 | status = acpi_remove_fixed_event_handler(ACPI_EVENT_GLOBAL, |
95 | acpi_ev_global_lock_handler); |
96 | |
97 | acpi_os_delete_lock(acpi_gbl_global_lock_pending_lock); |
98 | return_ACPI_STATUS(status); |
99 | } |
100 | |
101 | /******************************************************************************* |
102 | * |
103 | * FUNCTION: acpi_ev_global_lock_handler |
104 | * |
105 | * PARAMETERS: context - From thread interface, not used |
106 | * |
107 | * RETURN: ACPI_INTERRUPT_HANDLED |
108 | * |
109 | * DESCRIPTION: Invoked directly from the SCI handler when a global lock |
110 | * release interrupt occurs. If there is actually a pending |
111 | * request for the lock, signal the waiting thread. |
112 | * |
113 | ******************************************************************************/ |
114 | |
115 | static u32 acpi_ev_global_lock_handler(void *context) |
116 | { |
117 | acpi_status status; |
118 | acpi_cpu_flags flags; |
119 | |
120 | flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock); |
121 | |
122 | /* |
123 | * If a request for the global lock is not actually pending, |
124 | * we are done. This handles "spurious" global lock interrupts |
125 | * which are possible (and have been seen) with bad BIOSs. |
126 | */ |
127 | if (!acpi_gbl_global_lock_pending) { |
128 | goto cleanup_and_exit; |
129 | } |
130 | |
131 | /* |
132 | * Send a unit to the global lock semaphore. The actual acquisition |
133 | * of the global lock will be performed by the waiting thread. |
134 | */ |
135 | status = acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore, 1); |
136 | if (ACPI_FAILURE(status)) { |
137 | ACPI_ERROR((AE_INFO, "Could not signal Global Lock semaphore" )); |
138 | } |
139 | |
140 | acpi_gbl_global_lock_pending = FALSE; |
141 | |
142 | cleanup_and_exit: |
143 | |
144 | acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags); |
145 | return (ACPI_INTERRUPT_HANDLED); |
146 | } |
147 | |
148 | /****************************************************************************** |
149 | * |
150 | * FUNCTION: acpi_ev_acquire_global_lock |
151 | * |
152 | * PARAMETERS: timeout - Max time to wait for the lock, in millisec. |
153 | * |
154 | * RETURN: Status |
155 | * |
156 | * DESCRIPTION: Attempt to gain ownership of the Global Lock. |
157 | * |
158 | * MUTEX: Interpreter must be locked |
159 | * |
160 | * Note: The original implementation allowed multiple threads to "acquire" the |
161 | * Global Lock, and the OS would hold the lock until the last thread had |
162 | * released it. However, this could potentially starve the BIOS out of the |
163 | * lock, especially in the case where there is a tight handshake between the |
164 | * Embedded Controller driver and the BIOS. Therefore, this implementation |
165 | * allows only one thread to acquire the HW Global Lock at a time, and makes |
166 | * the global lock appear as a standard mutex on the OS side. |
167 | * |
168 | *****************************************************************************/ |
169 | |
170 | acpi_status acpi_ev_acquire_global_lock(u16 timeout) |
171 | { |
172 | acpi_cpu_flags flags; |
173 | acpi_status status; |
174 | u8 acquired = FALSE; |
175 | |
176 | ACPI_FUNCTION_TRACE(ev_acquire_global_lock); |
177 | |
178 | /* |
179 | * Only one thread can acquire the GL at a time, the global_lock_mutex |
180 | * enforces this. This interface releases the interpreter if we must wait. |
181 | */ |
182 | status = |
183 | acpi_ex_system_wait_mutex(acpi_gbl_global_lock_mutex->mutex. |
184 | os_mutex, timeout); |
185 | if (ACPI_FAILURE(status)) { |
186 | return_ACPI_STATUS(status); |
187 | } |
188 | |
189 | /* |
190 | * Update the global lock handle and check for wraparound. The handle is |
191 | * only used for the external global lock interfaces, but it is updated |
192 | * here to properly handle the case where a single thread may acquire the |
193 | * lock via both the AML and the acpi_acquire_global_lock interfaces. The |
194 | * handle is therefore updated on the first acquire from a given thread |
195 | * regardless of where the acquisition request originated. |
196 | */ |
197 | acpi_gbl_global_lock_handle++; |
198 | if (acpi_gbl_global_lock_handle == 0) { |
199 | acpi_gbl_global_lock_handle = 1; |
200 | } |
201 | |
202 | /* |
203 | * Make sure that a global lock actually exists. If not, just |
204 | * treat the lock as a standard mutex. |
205 | */ |
206 | if (!acpi_gbl_global_lock_present) { |
207 | acpi_gbl_global_lock_acquired = TRUE; |
208 | return_ACPI_STATUS(AE_OK); |
209 | } |
210 | |
211 | flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock); |
212 | |
213 | do { |
214 | |
215 | /* Attempt to acquire the actual hardware lock */ |
216 | |
217 | ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_FACS, acquired); |
218 | if (acquired) { |
219 | acpi_gbl_global_lock_acquired = TRUE; |
220 | ACPI_DEBUG_PRINT((ACPI_DB_EXEC, |
221 | "Acquired hardware Global Lock\n" )); |
222 | break; |
223 | } |
224 | |
225 | /* |
226 | * Did not get the lock. The pending bit was set above, and |
227 | * we must now wait until we receive the global lock |
228 | * released interrupt. |
229 | */ |
230 | acpi_gbl_global_lock_pending = TRUE; |
231 | acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags); |
232 | |
233 | ACPI_DEBUG_PRINT((ACPI_DB_EXEC, |
234 | "Waiting for hardware Global Lock\n" )); |
235 | |
236 | /* |
237 | * Wait for handshake with the global lock interrupt handler. |
238 | * This interface releases the interpreter if we must wait. |
239 | */ |
240 | status = |
241 | acpi_ex_system_wait_semaphore |
242 | (acpi_gbl_global_lock_semaphore, ACPI_WAIT_FOREVER); |
243 | |
244 | flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock); |
245 | |
246 | } while (ACPI_SUCCESS(status)); |
247 | |
248 | acpi_gbl_global_lock_pending = FALSE; |
249 | acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags); |
250 | |
251 | return_ACPI_STATUS(status); |
252 | } |
253 | |
254 | /******************************************************************************* |
255 | * |
256 | * FUNCTION: acpi_ev_release_global_lock |
257 | * |
258 | * PARAMETERS: None |
259 | * |
260 | * RETURN: Status |
261 | * |
262 | * DESCRIPTION: Releases ownership of the Global Lock. |
263 | * |
264 | ******************************************************************************/ |
265 | |
266 | acpi_status acpi_ev_release_global_lock(void) |
267 | { |
268 | u8 pending = FALSE; |
269 | acpi_status status = AE_OK; |
270 | |
271 | ACPI_FUNCTION_TRACE(ev_release_global_lock); |
272 | |
273 | /* Lock must be already acquired */ |
274 | |
275 | if (!acpi_gbl_global_lock_acquired) { |
276 | ACPI_WARNING((AE_INFO, |
277 | "Cannot release the ACPI Global Lock, it has not been acquired" )); |
278 | return_ACPI_STATUS(AE_NOT_ACQUIRED); |
279 | } |
280 | |
281 | if (acpi_gbl_global_lock_present) { |
282 | |
283 | /* Allow any thread to release the lock */ |
284 | |
285 | ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_FACS, pending); |
286 | |
287 | /* |
288 | * If the pending bit was set, we must write GBL_RLS to the control |
289 | * register |
290 | */ |
291 | if (pending) { |
292 | status = |
293 | acpi_write_bit_register |
294 | (ACPI_BITREG_GLOBAL_LOCK_RELEASE, |
295 | ACPI_ENABLE_EVENT); |
296 | } |
297 | |
298 | ACPI_DEBUG_PRINT((ACPI_DB_EXEC, |
299 | "Released hardware Global Lock\n" )); |
300 | } |
301 | |
302 | acpi_gbl_global_lock_acquired = FALSE; |
303 | |
304 | /* Release the local GL mutex */ |
305 | |
306 | acpi_os_release_mutex(acpi_gbl_global_lock_mutex->mutex.os_mutex); |
307 | return_ACPI_STATUS(status); |
308 | } |
309 | |
310 | #endif /* !ACPI_REDUCED_HARDWARE */ |
311 | |