drivers/acpi/acpica/evglock.c

   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 }