drivers/acpi/acpica/evglock.c

   1 /******************************************************************************
   2  *
   3  * Module Name: evglock - Global Lock support
   4  *
   5  *****************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2012, 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         /* 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
 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 }