1 /****************************************************************************** 2 * 3 * Module Name: evglock - Global Lock support 4 * 5 *****************************************************************************/ 6 7 /* 8 * Copyright (C) 2000 - 2011, 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 50 ACPI_MODULE_NAME("evglock") 51 52 /* Local prototypes */ 53 static 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 67 acpi_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 /* Attempt installation of the global lock handler */ 74 75 status = acpi_install_fixed_event_handler(ACPI_EVENT_GLOBAL, 76 acpi_ev_global_lock_handler, 77 NULL); 78 79 /* 80 * If the global lock does not exist on this platform, the attempt to 81 * enable GBL_STATUS will fail (the GBL_ENABLE bit will not stick). 82 * Map to AE_OK, but mark global lock as not present. Any attempt to 83 * actually use the global lock will be flagged with an error. 84 */ 85 acpi_gbl_global_lock_present = FALSE; 86 if (status == AE_NO_HARDWARE_RESPONSE) { 87 ACPI_ERROR((AE_INFO, 88 "No response from Global Lock hardware, disabling lock")); 89 90 return_ACPI_STATUS(AE_OK); 91 } 92 93 status = acpi_os_create_lock(&acpi_gbl_global_lock_pending_lock); 94 if (ACPI_FAILURE(status)) { 95 return_ACPI_STATUS(status); 96 } 97 98 acpi_gbl_global_lock_pending = FALSE; 99 acpi_gbl_global_lock_present = TRUE; 100 return_ACPI_STATUS(status); 101 } 102 103 /******************************************************************************* 104 * 105 * FUNCTION: acpi_ev_remove_global_lock_handler 106 * 107 * PARAMETERS: None 108 * 109 * RETURN: Status 110 * 111 * DESCRIPTION: Remove the handler for the Global Lock 112 * 113 ******************************************************************************/ 114 115 acpi_status acpi_ev_remove_global_lock_handler(void) 116 { 117 acpi_status status; 118 119 ACPI_FUNCTION_TRACE(ev_remove_global_lock_handler); 120 121 acpi_gbl_global_lock_present = FALSE; 122 status = acpi_remove_fixed_event_handler(ACPI_EVENT_GLOBAL, 123 acpi_ev_global_lock_handler); 124 125 return_ACPI_STATUS(status); 126 } 127 128 /******************************************************************************* 129 * 130 * FUNCTION: acpi_ev_global_lock_handler 131 * 132 * PARAMETERS: Context - From thread interface, not used 133 * 134 * RETURN: ACPI_INTERRUPT_HANDLED 135 * 136 * DESCRIPTION: Invoked directly from the SCI handler when a global lock 137 * release interrupt occurs. If there is actually a pending 138 * request for the lock, signal the waiting thread. 139 * 140 ******************************************************************************/ 141 142 static u32 acpi_ev_global_lock_handler(void *context) 143 { 144 acpi_status status; 145 acpi_cpu_flags flags; 146 147 flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock); 148 149 /* 150 * If a request for the global lock is not actually pending, 151 * we are done. This handles "spurious" global lock interrupts 152 * which are possible (and have been seen) with bad BIOSs. 153 */ 154 if (!acpi_gbl_global_lock_pending) { 155 goto cleanup_and_exit; 156 } 157 158 /* 159 * Send a unit to the global lock semaphore. The actual acquisition 160 * of the global lock will be performed by the waiting thread. 161 */ 162 status = acpi_os_signal_semaphore(acpi_gbl_global_lock_semaphore, 1); 163 if (ACPI_FAILURE(status)) { 164 ACPI_ERROR((AE_INFO, "Could not signal Global Lock semaphore")); 165 } 166 167 acpi_gbl_global_lock_pending = FALSE; 168 169 cleanup_and_exit: 170 171 acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags); 172 return (ACPI_INTERRUPT_HANDLED); 173 } 174 175 /****************************************************************************** 176 * 177 * FUNCTION: acpi_ev_acquire_global_lock 178 * 179 * PARAMETERS: Timeout - Max time to wait for the lock, in millisec. 180 * 181 * RETURN: Status 182 * 183 * DESCRIPTION: Attempt to gain ownership of the Global Lock. 184 * 185 * MUTEX: Interpreter must be locked 186 * 187 * Note: The original implementation allowed multiple threads to "acquire" the 188 * Global Lock, and the OS would hold the lock until the last thread had 189 * released it. However, this could potentially starve the BIOS out of the 190 * lock, especially in the case where there is a tight handshake between the 191 * Embedded Controller driver and the BIOS. Therefore, this implementation 192 * allows only one thread to acquire the HW Global Lock at a time, and makes 193 * the global lock appear as a standard mutex on the OS side. 194 * 195 *****************************************************************************/ 196 197 acpi_status acpi_ev_acquire_global_lock(u16 timeout) 198 { 199 acpi_cpu_flags flags; 200 acpi_status status; 201 u8 acquired = FALSE; 202 203 ACPI_FUNCTION_TRACE(ev_acquire_global_lock); 204 205 /* 206 * Only one thread can acquire the GL at a time, the global_lock_mutex 207 * enforces this. This interface releases the interpreter if we must wait. 208 */ 209 status = 210 acpi_ex_system_wait_mutex(acpi_gbl_global_lock_mutex->mutex. 211 os_mutex, timeout); 212 if (ACPI_FAILURE(status)) { 213 return_ACPI_STATUS(status); 214 } 215 216 /* 217 * Update the global lock handle and check for wraparound. The handle is 218 * only used for the external global lock interfaces, but it is updated 219 * here to properly handle the case where a single thread may acquire the 220 * lock via both the AML and the acpi_acquire_global_lock interfaces. The 221 * handle is therefore updated on the first acquire from a given thread 222 * regardless of where the acquisition request originated. 223 */ 224 acpi_gbl_global_lock_handle++; 225 if (acpi_gbl_global_lock_handle == 0) { 226 acpi_gbl_global_lock_handle = 1; 227 } 228 229 /* 230 * Make sure that a global lock actually exists. If not, just 231 * treat the lock as a standard mutex. 232 */ 233 if (!acpi_gbl_global_lock_present) { 234 acpi_gbl_global_lock_acquired = TRUE; 235 return_ACPI_STATUS(AE_OK); 236 } 237 238 flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock); 239 240 do { 241 242 /* Attempt to acquire the actual hardware lock */ 243 244 ACPI_ACQUIRE_GLOBAL_LOCK(acpi_gbl_FACS, acquired); 245 if (acquired) { 246 acpi_gbl_global_lock_acquired = TRUE; 247 ACPI_DEBUG_PRINT((ACPI_DB_EXEC, 248 "Acquired hardware Global Lock\n")); 249 break; 250 } 251 252 /* 253 * Did not get the lock. The pending bit was set above, and 254 * we must now wait until we receive the global lock 255 * released interrupt. 256 */ 257 acpi_gbl_global_lock_pending = TRUE; 258 acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags); 259 260 ACPI_DEBUG_PRINT((ACPI_DB_EXEC, 261 "Waiting for hardware Global Lock\n")); 262 263 /* 264 * Wait for handshake with the global lock interrupt handler. 265 * This interface releases the interpreter if we must wait. 266 */ 267 status = 268 acpi_ex_system_wait_semaphore 269 (acpi_gbl_global_lock_semaphore, ACPI_WAIT_FOREVER); 270 271 flags = acpi_os_acquire_lock(acpi_gbl_global_lock_pending_lock); 272 273 } while (ACPI_SUCCESS(status)); 274 275 acpi_gbl_global_lock_pending = FALSE; 276 acpi_os_release_lock(acpi_gbl_global_lock_pending_lock, flags); 277 278 return_ACPI_STATUS(status); 279 } 280 281 /******************************************************************************* 282 * 283 * FUNCTION: acpi_ev_release_global_lock 284 * 285 * PARAMETERS: None 286 * 287 * RETURN: Status 288 * 289 * DESCRIPTION: Releases ownership of the Global Lock. 290 * 291 ******************************************************************************/ 292 293 acpi_status acpi_ev_release_global_lock(void) 294 { 295 u8 pending = FALSE; 296 acpi_status status = AE_OK; 297 298 ACPI_FUNCTION_TRACE(ev_release_global_lock); 299 300 /* Lock must be already acquired */ 301 302 if (!acpi_gbl_global_lock_acquired) { 303 ACPI_WARNING((AE_INFO, 304 "Cannot release the ACPI Global Lock, it has not been acquired")); 305 return_ACPI_STATUS(AE_NOT_ACQUIRED); 306 } 307 308 if (acpi_gbl_global_lock_present) { 309 310 /* Allow any thread to release the lock */ 311 312 ACPI_RELEASE_GLOBAL_LOCK(acpi_gbl_FACS, pending); 313 314 /* 315 * If the pending bit was set, we must write GBL_RLS to the control 316 * register 317 */ 318 if (pending) { 319 status = 320 acpi_write_bit_register 321 (ACPI_BITREG_GLOBAL_LOCK_RELEASE, 322 ACPI_ENABLE_EVENT); 323 } 324 325 ACPI_DEBUG_PRINT((ACPI_DB_EXEC, 326 "Released hardware Global Lock\n")); 327 } 328 329 acpi_gbl_global_lock_acquired = FALSE; 330 331 /* Release the local GL mutex */ 332 333 acpi_os_release_mutex(acpi_gbl_global_lock_mutex->mutex.os_mutex); 334 return_ACPI_STATUS(status); 335 } 336