Bob Moore | 0f6896f | 2011-04-13 11:33:17 +0800 | [diff] [blame] | 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 | |
Bob Moore | 22e5b40 | 2011-11-16 10:57:28 +0800 | [diff] [blame] | 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 | |
Bob Moore | 0f6896f | 2011-04-13 11:33:17 +0800 | [diff] [blame] | 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 | |
| 121 | acpi_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 | |
| 148 | static 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 | |
| 203 | acpi_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 | |
| 299 | acpi_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 | } |