drivers/acpi/acpi_ipmi.c

   1 /*
   2  *  acpi_ipmi.c - ACPI IPMI opregion
   3  *
   4  *  Copyright (C) 2010, 2013 Intel Corporation
   5  *    Author: Zhao Yakui <yakui.zhao@intel.com>
   6  *            Lv Zheng <lv.zheng@intel.com>
   7  *
   8  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License as published by
  12  *  the Free Software Foundation; either version 2 of the License, or (at
  13  *  your option) any later version.
  14  *
  15  *  This program is distributed in the hope that it will be useful, but
  16  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  17  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  *  General Public License for more details.
  19  *
  20  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/acpi.h>
  25 #include <linux/ipmi.h>
  26 #include <linux/spinlock.h>
  27
  28 MODULE_AUTHOR("Zhao Yakui");
  29 MODULE_DESCRIPTION("ACPI IPMI Opregion driver");
  30 MODULE_LICENSE("GPL");
  31
  32 #define ACPI_IPMI_OK                    0
  33 #define ACPI_IPMI_TIMEOUT               0x10
  34 #define ACPI_IPMI_UNKNOWN               0x07
  35 /* the IPMI timeout is 5s */
  36 #define IPMI_TIMEOUT                    (5000)
  37 #define ACPI_IPMI_MAX_MSG_LENGTH        64
  38
  39 struct acpi_ipmi_device {
  40         /* the device list attached to driver_data.ipmi_devices */
  41         struct list_head head;
  42
  43         /* the IPMI request message list */
  44         struct list_head tx_msg_list;
  45
  46         spinlock_t tx_msg_lock;
  47         acpi_handle handle;
  48         struct device *dev;
  49         ipmi_user_t user_interface;
  50         int ipmi_ifnum; /* IPMI interface number */
  51         long curr_msgid;
  52         bool dead;
  53         struct kref kref;
  54 };
  55
  56 struct ipmi_driver_data {
  57         struct list_head ipmi_devices;
  58         struct ipmi_smi_watcher bmc_events;
  59         struct ipmi_user_hndl ipmi_hndlrs;
  60         struct mutex ipmi_lock;
  61
  62         /*
  63          * NOTE: IPMI System Interface Selection
  64          * There is no system interface specified by the IPMI operation
  65          * region access.  We try to select one system interface with ACPI
  66          * handle set.  IPMI messages passed from the ACPI codes are sent
  67          * to this selected global IPMI system interface.
  68          */
  69         struct acpi_ipmi_device *selected_smi;
  70 };
  71
  72 struct acpi_ipmi_msg {
  73         struct list_head head;
  74
  75         /*
  76          * General speaking the addr type should be SI_ADDR_TYPE. And
  77          * the addr channel should be BMC.
  78          * In fact it can also be IPMB type. But we will have to
  79          * parse it from the Netfn command buffer. It is so complex
  80          * that it is skipped.
  81          */
  82         struct ipmi_addr addr;
  83         long tx_msgid;
  84
  85         /* it is used to track whether the IPMI message is finished */
  86         struct completion tx_complete;
  87
  88         struct kernel_ipmi_msg tx_message;
  89         int msg_done;
  90
  91         /* tx/rx data . And copy it from/to ACPI object buffer */
  92         u8 data[ACPI_IPMI_MAX_MSG_LENGTH];
  93         u8 rx_len;
  94
  95         struct acpi_ipmi_device *device;
  96         struct kref kref;
  97 };
  98
  99 /* IPMI request/response buffer per ACPI 4.0, sec 5.5.2.4.3.2 */
 100 struct acpi_ipmi_buffer {
 101         u8 status;
 102         u8 length;
 103         u8 data[ACPI_IPMI_MAX_MSG_LENGTH];
 104 };
 105
 106 static void ipmi_register_bmc(int iface, struct device *dev);
 107 static void ipmi_bmc_gone(int iface);
 108 static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data);
 109
 110 static struct ipmi_driver_data driver_data = {
 111         .ipmi_devices = LIST_HEAD_INIT(driver_data.ipmi_devices),
 112         .bmc_events = {
 113                 .owner = THIS_MODULE,
 114                 .new_smi = ipmi_register_bmc,
 115                 .smi_gone = ipmi_bmc_gone,
 116         },
 117         .ipmi_hndlrs = {
 118                 .ipmi_recv_hndl = ipmi_msg_handler,
 119         },
 120         .ipmi_lock = __MUTEX_INITIALIZER(driver_data.ipmi_lock)
 121 };
 122
 123 static struct acpi_ipmi_device *
 124 ipmi_dev_alloc(int iface, struct device *dev, acpi_handle handle)
 125 {
 126         struct acpi_ipmi_device *ipmi_device;
 127         int err;
 128         ipmi_user_t user;
 129
 130         ipmi_device = kzalloc(sizeof(*ipmi_device), GFP_KERNEL);
 131         if (!ipmi_device)
 132                 return NULL;
 133
 134         kref_init(&ipmi_device->kref);
 135         INIT_LIST_HEAD(&ipmi_device->head);
 136         INIT_LIST_HEAD(&ipmi_device->tx_msg_list);
 137         spin_lock_init(&ipmi_device->tx_msg_lock);
 138         ipmi_device->handle = handle;
 139         ipmi_device->dev = get_device(dev);
 140         ipmi_device->ipmi_ifnum = iface;
 141
 142         err = ipmi_create_user(iface, &driver_data.ipmi_hndlrs,
 143                                ipmi_device, &user);
 144         if (err) {
 145                 put_device(dev);
 146                 kfree(ipmi_device);
 147                 return NULL;
 148         }
 149         ipmi_device->user_interface = user;
 150
 151         return ipmi_device;
 152 }
 153
 154 static void ipmi_dev_release(struct acpi_ipmi_device *ipmi_device)
 155 {
 156         ipmi_destroy_user(ipmi_device->user_interface);
 157         put_device(ipmi_device->dev);
 158         kfree(ipmi_device);
 159 }
 160
 161 static void ipmi_dev_release_kref(struct kref *kref)
 162 {
 163         struct acpi_ipmi_device *ipmi =
 164                 container_of(kref, struct acpi_ipmi_device, kref);
 165
 166         ipmi_dev_release(ipmi);
 167 }
 168
 169 static void __ipmi_dev_kill(struct acpi_ipmi_device *ipmi_device)
 170 {
 171         list_del(&ipmi_device->head);
 172         if (driver_data.selected_smi == ipmi_device)
 173                 driver_data.selected_smi = NULL;
 174
 175         /*
 176          * Always setting dead flag after deleting from the list or
 177          * list_for_each_entry() codes must get changed.
 178          */
 179         ipmi_device->dead = true;
 180 }
 181
 182 static struct acpi_ipmi_device *acpi_ipmi_dev_get(void)
 183 {
 184         struct acpi_ipmi_device *ipmi_device = NULL;
 185
 186         mutex_lock(&driver_data.ipmi_lock);
 187         if (driver_data.selected_smi) {
 188                 ipmi_device = driver_data.selected_smi;
 189                 kref_get(&ipmi_device->kref);
 190         }
 191         mutex_unlock(&driver_data.ipmi_lock);
 192
 193         return ipmi_device;
 194 }
 195
 196 static void acpi_ipmi_dev_put(struct acpi_ipmi_device *ipmi_device)
 197 {
 198         kref_put(&ipmi_device->kref, ipmi_dev_release_kref);
 199 }
 200
 201 static struct acpi_ipmi_msg *ipmi_msg_alloc(void)
 202 {
 203         struct acpi_ipmi_device *ipmi;
 204         struct acpi_ipmi_msg *ipmi_msg;
 205
 206         ipmi = acpi_ipmi_dev_get();
 207         if (!ipmi)
 208                 return NULL;
 209
 210         ipmi_msg = kzalloc(sizeof(struct acpi_ipmi_msg), GFP_KERNEL);
 211         if (!ipmi_msg) {
 212                 acpi_ipmi_dev_put(ipmi);
 213                 return NULL;
 214         }
 215
 216         kref_init(&ipmi_msg->kref);
 217         init_completion(&ipmi_msg->tx_complete);
 218         INIT_LIST_HEAD(&ipmi_msg->head);
 219         ipmi_msg->device = ipmi;
 220         ipmi_msg->msg_done = ACPI_IPMI_UNKNOWN;
 221
 222         return ipmi_msg;
 223 }
 224
 225 static void ipmi_msg_release(struct acpi_ipmi_msg *tx_msg)
 226 {
 227         acpi_ipmi_dev_put(tx_msg->device);
 228         kfree(tx_msg);
 229 }
 230
 231 static void ipmi_msg_release_kref(struct kref *kref)
 232 {
 233         struct acpi_ipmi_msg *tx_msg =
 234                 container_of(kref, struct acpi_ipmi_msg, kref);
 235
 236         ipmi_msg_release(tx_msg);
 237 }
 238
 239 static struct acpi_ipmi_msg *acpi_ipmi_msg_get(struct acpi_ipmi_msg *tx_msg)
 240 {
 241         kref_get(&tx_msg->kref);
 242
 243         return tx_msg;
 244 }
 245
 246 static void acpi_ipmi_msg_put(struct acpi_ipmi_msg *tx_msg)
 247 {
 248         kref_put(&tx_msg->kref, ipmi_msg_release_kref);
 249 }
 250
 251 #define IPMI_OP_RGN_NETFN(offset)       ((offset >> 8) & 0xff)
 252 #define IPMI_OP_RGN_CMD(offset)         (offset & 0xff)
 253 static int acpi_format_ipmi_request(struct acpi_ipmi_msg *tx_msg,
 254                                     acpi_physical_address address,
 255                                     acpi_integer *value)
 256 {
 257         struct kernel_ipmi_msg *msg;
 258         struct acpi_ipmi_buffer *buffer;
 259         struct acpi_ipmi_device *device;
 260         unsigned long flags;
 261
 262         msg = &tx_msg->tx_message;
 263
 264         /*
 265          * IPMI network function and command are encoded in the address
 266          * within the IPMI OpRegion; see ACPI 4.0, sec 5.5.2.4.3.
 267          */
 268         msg->netfn = IPMI_OP_RGN_NETFN(address);
 269         msg->cmd = IPMI_OP_RGN_CMD(address);
 270         msg->data = tx_msg->data;
 271
 272         /*
 273          * value is the parameter passed by the IPMI opregion space handler.
 274          * It points to the IPMI request message buffer
 275          */
 276         buffer = (struct acpi_ipmi_buffer *)value;
 277
 278         /* copy the tx message data */
 279         if (buffer->length > ACPI_IPMI_MAX_MSG_LENGTH) {
 280                 dev_WARN_ONCE(tx_msg->device->dev, true,
 281                               "Unexpected request (msg len %d).\n",
 282                               buffer->length);
 283                 return -EINVAL;
 284         }
 285         msg->data_len = buffer->length;
 286         memcpy(tx_msg->data, buffer->data, msg->data_len);
 287
 288         /*
 289          * now the default type is SYSTEM_INTERFACE and channel type is BMC.
 290          * If the netfn is APP_REQUEST and the cmd is SEND_MESSAGE,
 291          * the addr type should be changed to IPMB. Then we will have to parse
 292          * the IPMI request message buffer to get the IPMB address.
 293          * If so, please fix me.
 294          */
 295         tx_msg->addr.addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
 296         tx_msg->addr.channel = IPMI_BMC_CHANNEL;
 297         tx_msg->addr.data[0] = 0;
 298
 299         /* Get the msgid */
 300         device = tx_msg->device;
 301
 302         spin_lock_irqsave(&device->tx_msg_lock, flags);
 303         device->curr_msgid++;
 304         tx_msg->tx_msgid = device->curr_msgid;
 305         spin_unlock_irqrestore(&device->tx_msg_lock, flags);
 306
 307         return 0;
 308 }
 309
 310 static void acpi_format_ipmi_response(struct acpi_ipmi_msg *msg,
 311                                       acpi_integer *value)
 312 {
 313         struct acpi_ipmi_buffer *buffer;
 314
 315         /*
 316          * value is also used as output parameter. It represents the response
 317          * IPMI message returned by IPMI command.
 318          */
 319         buffer = (struct acpi_ipmi_buffer *)value;
 320
 321         /*
 322          * If the flag of msg_done is not set, it means that the IPMI command is
 323          * not executed correctly.
 324          */
 325         buffer->status = msg->msg_done;
 326         if (msg->msg_done != ACPI_IPMI_OK)
 327                 return;
 328
 329         /*
 330          * If the IPMI response message is obtained correctly, the status code
 331          * will be ACPI_IPMI_OK
 332          */
 333         buffer->length = msg->rx_len;
 334         memcpy(buffer->data, msg->data, msg->rx_len);
 335 }
 336
 337 static void ipmi_flush_tx_msg(struct acpi_ipmi_device *ipmi)
 338 {
 339         struct acpi_ipmi_msg *tx_msg;
 340         unsigned long flags;
 341
 342         /*
 343          * NOTE: On-going ipmi_recv_msg
 344          * ipmi_msg_handler() may still be invoked by ipmi_si after
 345          * flushing.  But it is safe to do a fast flushing on module_exit()
 346          * without waiting for all ipmi_recv_msg(s) to complete from
 347          * ipmi_msg_handler() as it is ensured by ipmi_si that all
 348          * ipmi_recv_msg(s) are freed after invoking ipmi_destroy_user().
 349          */
 350         spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
 351         while (!list_empty(&ipmi->tx_msg_list)) {
 352                 tx_msg = list_first_entry(&ipmi->tx_msg_list,
 353                                           struct acpi_ipmi_msg,
 354                                           head);
 355                 list_del(&tx_msg->head);
 356                 spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
 357
 358                 /* wake up the sleep thread on the Tx msg */
 359                 complete(&tx_msg->tx_complete);
 360                 acpi_ipmi_msg_put(tx_msg);
 361                 spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
 362         }
 363         spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
 364 }
 365
 366 static void ipmi_cancel_tx_msg(struct acpi_ipmi_device *ipmi,
 367                                struct acpi_ipmi_msg *msg)
 368 {
 369         struct acpi_ipmi_msg *tx_msg, *temp;
 370         bool msg_found = false;
 371         unsigned long flags;
 372
 373         spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
 374         list_for_each_entry_safe(tx_msg, temp, &ipmi->tx_msg_list, head) {
 375                 if (msg == tx_msg) {
 376                         msg_found = true;
 377                         list_del(&tx_msg->head);
 378                         break;
 379                 }
 380         }
 381         spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
 382
 383         if (msg_found)
 384                 acpi_ipmi_msg_put(tx_msg);
 385 }
 386
 387 static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
 388 {
 389         struct acpi_ipmi_device *ipmi_device = user_msg_data;
 390         bool msg_found = false;
 391         struct acpi_ipmi_msg *tx_msg, *temp;
 392         struct device *dev = ipmi_device->dev;
 393         unsigned long flags;
 394
 395         if (msg->user != ipmi_device->user_interface) {
 396                 dev_warn(dev,
 397                          "Unexpected response is returned. returned user %p, expected user %p\n",
 398                          msg->user, ipmi_device->user_interface);
 399                 goto out_msg;
 400         }
 401
 402         spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
 403         list_for_each_entry_safe(tx_msg, temp, &ipmi_device->tx_msg_list, head) {
 404                 if (msg->msgid == tx_msg->tx_msgid) {
 405                         msg_found = true;
 406                         list_del(&tx_msg->head);
 407                         break;
 408                 }
 409         }
 410         spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
 411
 412         if (!msg_found) {
 413                 dev_warn(dev,
 414                          "Unexpected response (msg id %ld) is returned.\n",
 415                          msg->msgid);
 416                 goto out_msg;
 417         }
 418
 419         /* copy the response data to Rx_data buffer */
 420         if (msg->msg.data_len > ACPI_IPMI_MAX_MSG_LENGTH) {
 421                 dev_WARN_ONCE(dev, true,
 422                               "Unexpected response (msg len %d).\n",
 423                               msg->msg.data_len);
 424                 goto out_comp;
 425         }
 426
 427         /* response msg is an error msg */
 428         msg->recv_type = IPMI_RESPONSE_RECV_TYPE;
 429         if (msg->recv_type == IPMI_RESPONSE_RECV_TYPE &&
 430             msg->msg.data_len == 1) {
 431                 if (msg->msg.data[0] == IPMI_TIMEOUT_COMPLETION_CODE) {
 432                         dev_WARN_ONCE(dev, true,
 433                                       "Unexpected response (timeout).\n");
 434                         tx_msg->msg_done = ACPI_IPMI_TIMEOUT;
 435                 }
 436                 goto out_comp;
 437         }
 438
 439         tx_msg->rx_len = msg->msg.data_len;
 440         memcpy(tx_msg->data, msg->msg.data, tx_msg->rx_len);
 441         tx_msg->msg_done = ACPI_IPMI_OK;
 442
 443 out_comp:
 444         complete(&tx_msg->tx_complete);
 445         acpi_ipmi_msg_put(tx_msg);
 446 out_msg:
 447         ipmi_free_recv_msg(msg);
 448 }
 449
 450 static void ipmi_register_bmc(int iface, struct device *dev)
 451 {
 452         struct acpi_ipmi_device *ipmi_device, *temp;
 453         int err;
 454         struct ipmi_smi_info smi_data;
 455         acpi_handle handle;
 456
 457         err = ipmi_get_smi_info(iface, &smi_data);
 458         if (err)
 459                 return;
 460
 461         if (smi_data.addr_src != SI_ACPI)
 462                 goto err_ref;
 463         handle = smi_data.addr_info.acpi_info.acpi_handle;
 464         if (!handle)
 465                 goto err_ref;
 466
 467         ipmi_device = ipmi_dev_alloc(iface, smi_data.dev, handle);
 468         if (!ipmi_device) {
 469                 dev_warn(smi_data.dev, "Can't create IPMI user interface\n");
 470                 goto err_ref;
 471         }
 472
 473         mutex_lock(&driver_data.ipmi_lock);
 474         list_for_each_entry(temp, &driver_data.ipmi_devices, head) {
 475                 /*
 476                  * if the corresponding ACPI handle is already added
 477                  * to the device list, don't add it again.
 478                  */
 479                 if (temp->handle == handle)
 480                         goto err_lock;
 481         }
 482         if (!driver_data.selected_smi)
 483                 driver_data.selected_smi = ipmi_device;
 484         list_add_tail(&ipmi_device->head, &driver_data.ipmi_devices);
 485         mutex_unlock(&driver_data.ipmi_lock);
 486
 487         put_device(smi_data.dev);
 488         return;
 489
 490 err_lock:
 491         mutex_unlock(&driver_data.ipmi_lock);
 492         ipmi_dev_release(ipmi_device);
 493 err_ref:
 494         put_device(smi_data.dev);
 495         return;
 496 }
 497
 498 static void ipmi_bmc_gone(int iface)
 499 {
 500         struct acpi_ipmi_device *ipmi_device, *temp;
 501         bool dev_found = false;
 502
 503         mutex_lock(&driver_data.ipmi_lock);
 504         list_for_each_entry_safe(ipmi_device, temp,
 505                                  &driver_data.ipmi_devices, head) {
 506                 if (ipmi_device->ipmi_ifnum != iface) {
 507                         dev_found = true;
 508                         __ipmi_dev_kill(ipmi_device);
 509                         break;
 510                 }
 511         }
 512         if (!driver_data.selected_smi)
 513                 driver_data.selected_smi = list_first_entry_or_null(
 514                                         &driver_data.ipmi_devices,
 515                                         struct acpi_ipmi_device, head);
 516         mutex_unlock(&driver_data.ipmi_lock);
 517
 518         if (dev_found) {
 519                 ipmi_flush_tx_msg(ipmi_device);
 520                 acpi_ipmi_dev_put(ipmi_device);
 521         }
 522 }
 523
 524 /*
 525  * This is the IPMI opregion space handler.
 526  * @function: indicates the read/write. In fact as the IPMI message is driven
 527  * by command, only write is meaningful.
 528  * @address: This contains the netfn/command of IPMI request message.
 529  * @bits   : not used.
 530  * @value  : it is an in/out parameter. It points to the IPMI message buffer.
 531  *           Before the IPMI message is sent, it represents the actual request
 532  *           IPMI message. After the IPMI message is finished, it represents
 533  *           the response IPMI message returned by IPMI command.
 534  * @handler_context: IPMI device context.
 535  */
 536 static acpi_status
 537 acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
 538                         u32 bits, acpi_integer *value,
 539                         void *handler_context, void *region_context)
 540 {
 541         struct acpi_ipmi_msg *tx_msg;
 542         struct acpi_ipmi_device *ipmi_device;
 543         int err;
 544         acpi_status status;
 545         unsigned long flags;
 546
 547         /*
 548          * IPMI opregion message.
 549          * IPMI message is firstly written to the BMC and system software
 550          * can get the respsonse. So it is unmeaningful for the read access
 551          * of IPMI opregion.
 552          */
 553         if ((function & ACPI_IO_MASK) == ACPI_READ)
 554                 return AE_TYPE;
 555
 556         tx_msg = ipmi_msg_alloc();
 557         if (!tx_msg)
 558                 return AE_NOT_EXIST;
 559         ipmi_device = tx_msg->device;
 560
 561         if (acpi_format_ipmi_request(tx_msg, address, value) != 0) {
 562                 ipmi_msg_release(tx_msg);
 563                 return AE_TYPE;
 564         }
 565
 566         acpi_ipmi_msg_get(tx_msg);
 567         mutex_lock(&driver_data.ipmi_lock);
 568         /* Do not add a tx_msg that can not be flushed. */
 569         if (ipmi_device->dead) {
 570                 mutex_unlock(&driver_data.ipmi_lock);
 571                 ipmi_msg_release(tx_msg);
 572                 return AE_NOT_EXIST;
 573         }
 574         spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
 575         list_add_tail(&tx_msg->head, &ipmi_device->tx_msg_list);
 576         spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
 577         mutex_unlock(&driver_data.ipmi_lock);
 578
 579         err = ipmi_request_settime(ipmi_device->user_interface,
 580                                    &tx_msg->addr,
 581                                    tx_msg->tx_msgid,
 582                                    &tx_msg->tx_message,
 583                                    NULL, 0, 0, IPMI_TIMEOUT);
 584         if (err) {
 585                 status = AE_ERROR;
 586                 goto out_msg;
 587         }
 588         wait_for_completion(&tx_msg->tx_complete);
 589
 590         acpi_format_ipmi_response(tx_msg, value);
 591         status = AE_OK;
 592
 593 out_msg:
 594         ipmi_cancel_tx_msg(ipmi_device, tx_msg);
 595         acpi_ipmi_msg_put(tx_msg);
 596         return status;
 597 }
 598
 599 static int __init acpi_ipmi_init(void)
 600 {
 601         int result;
 602         acpi_status status;
 603
 604         if (acpi_disabled)
 605                 return 0;
 606
 607         status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
 608                                                     ACPI_ADR_SPACE_IPMI,
 609                                                     &acpi_ipmi_space_handler,
 610                                                     NULL, NULL);
 611         if (ACPI_FAILURE(status)) {
 612                 pr_warn("Can't register IPMI opregion space handle\n");
 613                 return -EINVAL;
 614         }
 615         result = ipmi_smi_watcher_register(&driver_data.bmc_events);
 616         if (result)
 617                 pr_err("Can't register IPMI system interface watcher\n");
 618
 619         return result;
 620 }
 621
 622 static void __exit acpi_ipmi_exit(void)
 623 {
 624         struct acpi_ipmi_device *ipmi_device;
 625
 626         if (acpi_disabled)
 627                 return;
 628
 629         ipmi_smi_watcher_unregister(&driver_data.bmc_events);
 630
 631         /*
 632          * When one smi_watcher is unregistered, it is only deleted
 633          * from the smi_watcher list. But the smi_gone callback function
 634          * is not called. So explicitly uninstall the ACPI IPMI oregion
 635          * handler and free it.
 636          */
 637         mutex_lock(&driver_data.ipmi_lock);
 638         while (!list_empty(&driver_data.ipmi_devices)) {
 639                 ipmi_device = list_first_entry(&driver_data.ipmi_devices,
 640                                                struct acpi_ipmi_device,
 641                                                head);
 642                 __ipmi_dev_kill(ipmi_device);
 643                 mutex_unlock(&driver_data.ipmi_lock);
 644
 645                 ipmi_flush_tx_msg(ipmi_device);
 646                 acpi_ipmi_dev_put(ipmi_device);
 647
 648                 mutex_lock(&driver_data.ipmi_lock);
 649         }
 650         mutex_unlock(&driver_data.ipmi_lock);
 651         acpi_remove_address_space_handler(ACPI_ROOT_OBJECT,
 652                                           ACPI_ADR_SPACE_IPMI,
 653                                           &acpi_ipmi_space_handler);
 654 }
 655
 656 module_init(acpi_ipmi_init);
 657 module_exit(acpi_ipmi_exit);