kernel/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  *  You should have received a copy of the GNU General Public License along
  21  *  with this program; if not, write to the Free Software Foundation, Inc.,
  22  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  23  *
  24  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  25  */
  26
  27 #include <linux/module.h>
  28 #include <linux/acpi.h>
  29 #include <linux/ipmi.h>
  30 #include <linux/spinlock.h>
  31
  32 MODULE_AUTHOR("Zhao Yakui");
  33 MODULE_DESCRIPTION("ACPI IPMI Opregion driver");
  34 MODULE_LICENSE("GPL");
  35
  36 #define ACPI_IPMI_OK                    0
  37 #define ACPI_IPMI_TIMEOUT               0x10
  38 #define ACPI_IPMI_UNKNOWN               0x07
  39 /* the IPMI timeout is 5s */
  40 #define IPMI_TIMEOUT                    (5000)
  41 #define ACPI_IPMI_MAX_MSG_LENGTH        64
  42
  43 struct acpi_ipmi_device {
  44         /* the device list attached to driver_data.ipmi_devices */
  45         struct list_head head;
  46
  47         /* the IPMI request message list */
  48         struct list_head tx_msg_list;
  49
  50         spinlock_t tx_msg_lock;
  51         acpi_handle handle;
  52         struct device *dev;
  53         ipmi_user_t user_interface;
  54         int ipmi_ifnum; /* IPMI interface number */
  55         long curr_msgid;
  56         bool dead;
  57         struct kref kref;
  58 };
  59
  60 struct ipmi_driver_data {
  61         struct list_head ipmi_devices;
  62         struct ipmi_smi_watcher bmc_events;
  63         struct ipmi_user_hndl ipmi_hndlrs;
  64         struct mutex ipmi_lock;
  65
  66         /*
  67          * NOTE: IPMI System Interface Selection
  68          * There is no system interface specified by the IPMI operation
  69          * region access.  We try to select one system interface with ACPI
  70          * handle set.  IPMI messages passed from the ACPI codes are sent
  71          * to this selected global IPMI system interface.
  72          */
  73         struct acpi_ipmi_device *selected_smi;
  74 };
  75
  76 struct acpi_ipmi_msg {
  77         struct list_head head;
  78
  79         /*
  80          * General speaking the addr type should be SI_ADDR_TYPE. And
  81          * the addr channel should be BMC.
  82          * In fact it can also be IPMB type. But we will have to
  83          * parse it from the Netfn command buffer. It is so complex
  84          * that it is skipped.
  85          */
  86         struct ipmi_addr addr;
  87         long tx_msgid;
  88
  89         /* it is used to track whether the IPMI message is finished */
  90         struct completion tx_complete;
  91
  92         struct kernel_ipmi_msg tx_message;
  93         int msg_done;
  94
  95         /* tx/rx data . And copy it from/to ACPI object buffer */
  96         u8 data[ACPI_IPMI_MAX_MSG_LENGTH];
  97         u8 rx_len;
  98
  99         struct acpi_ipmi_device *device;
 100         struct kref kref;
 101 };
 102
 103 /* IPMI request/response buffer per ACPI 4.0, sec 5.5.2.4.3.2 */
 104 struct acpi_ipmi_buffer {
 105         u8 status;
 106         u8 length;
 107         u8 data[ACPI_IPMI_MAX_MSG_LENGTH];
 108 };
 109
 110 static void ipmi_register_bmc(int iface, struct device *dev);
 111 static void ipmi_bmc_gone(int iface);
 112 static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data);
 113
 114 static struct ipmi_driver_data driver_data = {
 115         .ipmi_devices = LIST_HEAD_INIT(driver_data.ipmi_devices),
 116         .bmc_events = {
 117                 .owner = THIS_MODULE,
 118                 .new_smi = ipmi_register_bmc,
 119                 .smi_gone = ipmi_bmc_gone,
 120         },
 121         .ipmi_hndlrs = {
 122                 .ipmi_recv_hndl = ipmi_msg_handler,
 123         },
 124         .ipmi_lock = __MUTEX_INITIALIZER(driver_data.ipmi_lock)
 125 };
 126
 127 static struct acpi_ipmi_device *
 128 ipmi_dev_alloc(int iface, struct device *dev, acpi_handle handle)
 129 {
 130         struct acpi_ipmi_device *ipmi_device;
 131         int err;
 132         ipmi_user_t user;
 133
 134         ipmi_device = kzalloc(sizeof(*ipmi_device), GFP_KERNEL);
 135         if (!ipmi_device)
 136                 return NULL;
 137
 138         kref_init(&ipmi_device->kref);
 139         INIT_LIST_HEAD(&ipmi_device->head);
 140         INIT_LIST_HEAD(&ipmi_device->tx_msg_list);
 141         spin_lock_init(&ipmi_device->tx_msg_lock);
 142         ipmi_device->handle = handle;
 143         ipmi_device->dev = get_device(dev);
 144         ipmi_device->ipmi_ifnum = iface;
 145
 146         err = ipmi_create_user(iface, &driver_data.ipmi_hndlrs,
 147                                ipmi_device, &user);
 148         if (err) {
 149                 put_device(dev);
 150                 kfree(ipmi_device);
 151                 return NULL;
 152         }
 153         ipmi_device->user_interface = user;
 154
 155         return ipmi_device;
 156 }
 157
 158 static void ipmi_dev_release(struct acpi_ipmi_device *ipmi_device)
 159 {
 160         ipmi_destroy_user(ipmi_device->user_interface);
 161         put_device(ipmi_device->dev);
 162         kfree(ipmi_device);
 163 }
 164
 165 static void ipmi_dev_release_kref(struct kref *kref)
 166 {
 167         struct acpi_ipmi_device *ipmi =
 168                 container_of(kref, struct acpi_ipmi_device, kref);
 169
 170         ipmi_dev_release(ipmi);
 171 }
 172
 173 static void __ipmi_dev_kill(struct acpi_ipmi_device *ipmi_device)
 174 {
 175         list_del(&ipmi_device->head);
 176         if (driver_data.selected_smi == ipmi_device)
 177                 driver_data.selected_smi = NULL;
 178
 179         /*
 180          * Always setting dead flag after deleting from the list or
 181          * list_for_each_entry() codes must get changed.
 182          */
 183         ipmi_device->dead = true;
 184 }
 185
 186 static struct acpi_ipmi_device *acpi_ipmi_dev_get(void)
 187 {
 188         struct acpi_ipmi_device *ipmi_device = NULL;
 189
 190         mutex_lock(&driver_data.ipmi_lock);
 191         if (driver_data.selected_smi) {
 192                 ipmi_device = driver_data.selected_smi;
 193                 kref_get(&ipmi_device->kref);
 194         }
 195         mutex_unlock(&driver_data.ipmi_lock);
 196
 197         return ipmi_device;
 198 }
 199
 200 static void acpi_ipmi_dev_put(struct acpi_ipmi_device *ipmi_device)
 201 {
 202         kref_put(&ipmi_device->kref, ipmi_dev_release_kref);
 203 }
 204
 205 static struct acpi_ipmi_msg *ipmi_msg_alloc(void)
 206 {
 207         struct acpi_ipmi_device *ipmi;
 208         struct acpi_ipmi_msg *ipmi_msg;
 209
 210         ipmi = acpi_ipmi_dev_get();
 211         if (!ipmi)
 212                 return NULL;
 213
 214         ipmi_msg = kzalloc(sizeof(struct acpi_ipmi_msg), GFP_KERNEL);
 215         if (!ipmi_msg) {
 216                 acpi_ipmi_dev_put(ipmi);
 217                 return NULL;
 218         }
 219
 220         kref_init(&ipmi_msg->kref);
 221         init_completion(&ipmi_msg->tx_complete);
 222         INIT_LIST_HEAD(&ipmi_msg->head);
 223         ipmi_msg->device = ipmi;
 224         ipmi_msg->msg_done = ACPI_IPMI_UNKNOWN;
 225
 226         return ipmi_msg;
 227 }
 228
 229 static void ipmi_msg_release(struct acpi_ipmi_msg *tx_msg)
 230 {
 231         acpi_ipmi_dev_put(tx_msg->device);
 232         kfree(tx_msg);
 233 }
 234
 235 static void ipmi_msg_release_kref(struct kref *kref)
 236 {
 237         struct acpi_ipmi_msg *tx_msg =
 238                 container_of(kref, struct acpi_ipmi_msg, kref);
 239
 240         ipmi_msg_release(tx_msg);
 241 }
 242
 243 static struct acpi_ipmi_msg *acpi_ipmi_msg_get(struct acpi_ipmi_msg *tx_msg)
 244 {
 245         kref_get(&tx_msg->kref);
 246
 247         return tx_msg;
 248 }
 249
 250 static void acpi_ipmi_msg_put(struct acpi_ipmi_msg *tx_msg)
 251 {
 252         kref_put(&tx_msg->kref, ipmi_msg_release_kref);
 253 }
 254
 255 #define IPMI_OP_RGN_NETFN(offset)       ((offset >> 8) & 0xff)
 256 #define IPMI_OP_RGN_CMD(offset)         (offset & 0xff)
 257 static int acpi_format_ipmi_request(struct acpi_ipmi_msg *tx_msg,
 258                                     acpi_physical_address address,
 259                                     acpi_integer *value)
 260 {
 261         struct kernel_ipmi_msg *msg;
 262         struct acpi_ipmi_buffer *buffer;
 263         struct acpi_ipmi_device *device;
 264         unsigned long flags;
 265
 266         msg = &tx_msg->tx_message;
 267
 268         /*
 269          * IPMI network function and command are encoded in the address
 270          * within the IPMI OpRegion; see ACPI 4.0, sec 5.5.2.4.3.
 271          */
 272         msg->netfn = IPMI_OP_RGN_NETFN(address);
 273         msg->cmd = IPMI_OP_RGN_CMD(address);
 274         msg->data = tx_msg->data;
 275
 276         /*
 277          * value is the parameter passed by the IPMI opregion space handler.
 278          * It points to the IPMI request message buffer
 279          */
 280         buffer = (struct acpi_ipmi_buffer *)value;
 281
 282         /* copy the tx message data */
 283         if (buffer->length > ACPI_IPMI_MAX_MSG_LENGTH) {
 284                 dev_WARN_ONCE(tx_msg->device->dev, true,
 285                               "Unexpected request (msg len %d).\n",
 286                               buffer->length);
 287                 return -EINVAL;
 288         }
 289         msg->data_len = buffer->length;
 290         memcpy(tx_msg->data, buffer->data, msg->data_len);
 291
 292         /*
 293          * now the default type is SYSTEM_INTERFACE and channel type is BMC.
 294          * If the netfn is APP_REQUEST and the cmd is SEND_MESSAGE,
 295          * the addr type should be changed to IPMB. Then we will have to parse
 296          * the IPMI request message buffer to get the IPMB address.
 297          * If so, please fix me.
 298          */
 299         tx_msg->addr.addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
 300         tx_msg->addr.channel = IPMI_BMC_CHANNEL;
 301         tx_msg->addr.data[0] = 0;
 302
 303         /* Get the msgid */
 304         device = tx_msg->device;
 305
 306         spin_lock_irqsave(&device->tx_msg_lock, flags);
 307         device->curr_msgid++;
 308         tx_msg->tx_msgid = device->curr_msgid;
 309         spin_unlock_irqrestore(&device->tx_msg_lock, flags);
 310
 311         return 0;
 312 }
 313
 314 static void acpi_format_ipmi_response(struct acpi_ipmi_msg *msg,
 315                                       acpi_integer *value)
 316 {
 317         struct acpi_ipmi_buffer *buffer;
 318
 319         /*
 320          * value is also used as output parameter. It represents the response
 321          * IPMI message returned by IPMI command.
 322          */
 323         buffer = (struct acpi_ipmi_buffer *)value;
 324
 325         /*
 326          * If the flag of msg_done is not set, it means that the IPMI command is
 327          * not executed correctly.
 328          */
 329         buffer->status = msg->msg_done;
 330         if (msg->msg_done != ACPI_IPMI_OK)
 331                 return;
 332
 333         /*
 334          * If the IPMI response message is obtained correctly, the status code
 335          * will be ACPI_IPMI_OK
 336          */
 337         buffer->length = msg->rx_len;
 338         memcpy(buffer->data, msg->data, msg->rx_len);
 339 }
 340
 341 static void ipmi_flush_tx_msg(struct acpi_ipmi_device *ipmi)
 342 {
 343         struct acpi_ipmi_msg *tx_msg;
 344         unsigned long flags;
 345
 346         /*
 347          * NOTE: On-going ipmi_recv_msg
 348          * ipmi_msg_handler() may still be invoked by ipmi_si after
 349          * flushing.  But it is safe to do a fast flushing on module_exit()
 350          * without waiting for all ipmi_recv_msg(s) to complete from
 351          * ipmi_msg_handler() as it is ensured by ipmi_si that all
 352          * ipmi_recv_msg(s) are freed after invoking ipmi_destroy_user().
 353          */
 354         spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
 355         while (!list_empty(&ipmi->tx_msg_list)) {
 356                 tx_msg = list_first_entry(&ipmi->tx_msg_list,
 357                                           struct acpi_ipmi_msg,
 358                                           head);
 359                 list_del(&tx_msg->head);
 360                 spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
 361
 362                 /* wake up the sleep thread on the Tx msg */
 363                 complete(&tx_msg->tx_complete);
 364                 acpi_ipmi_msg_put(tx_msg);
 365                 spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
 366         }
 367         spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
 368 }
 369
 370 static void ipmi_cancel_tx_msg(struct acpi_ipmi_device *ipmi,
 371                                struct acpi_ipmi_msg *msg)
 372 {
 373         struct acpi_ipmi_msg *tx_msg, *temp;
 374         bool msg_found = false;
 375         unsigned long flags;
 376
 377         spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
 378         list_for_each_entry_safe(tx_msg, temp, &ipmi->tx_msg_list, head) {
 379                 if (msg == tx_msg) {
 380                         msg_found = true;
 381                         list_del(&tx_msg->head);
 382                         break;
 383                 }
 384         }
 385         spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
 386
 387         if (msg_found)
 388                 acpi_ipmi_msg_put(tx_msg);
 389 }
 390
 391 static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
 392 {
 393         struct acpi_ipmi_device *ipmi_device = user_msg_data;
 394         bool msg_found = false;
 395         struct acpi_ipmi_msg *tx_msg, *temp;
 396         struct device *dev = ipmi_device->dev;
 397         unsigned long flags;
 398
 399         if (msg->user != ipmi_device->user_interface) {
 400                 dev_warn(dev,
 401                          "Unexpected response is returned. returned user %p, expected user %p\n",
 402                          msg->user, ipmi_device->user_interface);
 403                 goto out_msg;
 404         }
 405
 406         spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
 407         list_for_each_entry_safe(tx_msg, temp, &ipmi_device->tx_msg_list, head) {
 408                 if (msg->msgid == tx_msg->tx_msgid) {
 409                         msg_found = true;
 410                         list_del(&tx_msg->head);
 411                         break;
 412                 }
 413         }
 414         spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
 415
 416         if (!msg_found) {
 417                 dev_warn(dev,
 418                          "Unexpected response (msg id %ld) is returned.\n",
 419                          msg->msgid);
 420                 goto out_msg;
 421         }
 422
 423         /* copy the response data to Rx_data buffer */
 424         if (msg->msg.data_len > ACPI_IPMI_MAX_MSG_LENGTH) {
 425                 dev_WARN_ONCE(dev, true,
 426                               "Unexpected response (msg len %d).\n",
 427                               msg->msg.data_len);
 428                 goto out_comp;
 429         }
 430
 431         /* response msg is an error msg */
 432         msg->recv_type = IPMI_RESPONSE_RECV_TYPE;
 433         if (msg->recv_type == IPMI_RESPONSE_RECV_TYPE &&
 434             msg->msg.data_len == 1) {
 435                 if (msg->msg.data[0] == IPMI_TIMEOUT_COMPLETION_CODE) {
 436                         dev_WARN_ONCE(dev, true,
 437                                       "Unexpected response (timeout).\n");
 438                         tx_msg->msg_done = ACPI_IPMI_TIMEOUT;
 439                 }
 440                 goto out_comp;
 441         }
 442
 443         tx_msg->rx_len = msg->msg.data_len;
 444         memcpy(tx_msg->data, msg->msg.data, tx_msg->rx_len);
 445         tx_msg->msg_done = ACPI_IPMI_OK;
 446
 447 out_comp:
 448         complete(&tx_msg->tx_complete);
 449         acpi_ipmi_msg_put(tx_msg);
 450 out_msg:
 451         ipmi_free_recv_msg(msg);
 452 }
 453
 454 static void ipmi_register_bmc(int iface, struct device *dev)
 455 {
 456         struct acpi_ipmi_device *ipmi_device, *temp;
 457         int err;
 458         struct ipmi_smi_info smi_data;
 459         acpi_handle handle;
 460
 461         err = ipmi_get_smi_info(iface, &smi_data);
 462         if (err)
 463                 return;
 464
 465         if (smi_data.addr_src != SI_ACPI)
 466                 goto err_ref;
 467         handle = smi_data.addr_info.acpi_info.acpi_handle;
 468         if (!handle)
 469                 goto err_ref;
 470
 471         ipmi_device = ipmi_dev_alloc(iface, smi_data.dev, handle);
 472         if (!ipmi_device) {
 473                 dev_warn(smi_data.dev, "Can't create IPMI user interface\n");
 474                 goto err_ref;
 475         }
 476
 477         mutex_lock(&driver_data.ipmi_lock);
 478         list_for_each_entry(temp, &driver_data.ipmi_devices, head) {
 479                 /*
 480                  * if the corresponding ACPI handle is already added
 481                  * to the device list, don't add it again.
 482                  */
 483                 if (temp->handle == handle)
 484                         goto err_lock;
 485         }
 486         if (!driver_data.selected_smi)
 487                 driver_data.selected_smi = ipmi_device;
 488         list_add_tail(&ipmi_device->head, &driver_data.ipmi_devices);
 489         mutex_unlock(&driver_data.ipmi_lock);
 490
 491         put_device(smi_data.dev);
 492         return;
 493
 494 err_lock:
 495         mutex_unlock(&driver_data.ipmi_lock);
 496         ipmi_dev_release(ipmi_device);
 497 err_ref:
 498         put_device(smi_data.dev);
 499         return;
 500 }
 501
 502 static void ipmi_bmc_gone(int iface)
 503 {
 504         struct acpi_ipmi_device *ipmi_device, *temp;
 505         bool dev_found = false;
 506
 507         mutex_lock(&driver_data.ipmi_lock);
 508         list_for_each_entry_safe(ipmi_device, temp,
 509                                  &driver_data.ipmi_devices, head) {
 510                 if (ipmi_device->ipmi_ifnum != iface) {
 511                         dev_found = true;
 512                         __ipmi_dev_kill(ipmi_device);
 513                         break;
 514                 }
 515         }
 516         if (!driver_data.selected_smi)
 517                 driver_data.selected_smi = list_first_entry_or_null(
 518                                         &driver_data.ipmi_devices,
 519                                         struct acpi_ipmi_device, head);
 520         mutex_unlock(&driver_data.ipmi_lock);
 521
 522         if (dev_found) {
 523                 ipmi_flush_tx_msg(ipmi_device);
 524                 acpi_ipmi_dev_put(ipmi_device);
 525         }
 526 }
 527
 528 /*
 529  * This is the IPMI opregion space handler.
 530  * @function: indicates the read/write. In fact as the IPMI message is driven
 531  * by command, only write is meaningful.
 532  * @address: This contains the netfn/command of IPMI request message.
 533  * @bits   : not used.
 534  * @value  : it is an in/out parameter. It points to the IPMI message buffer.
 535  *           Before the IPMI message is sent, it represents the actual request
 536  *           IPMI message. After the IPMI message is finished, it represents
 537  *           the response IPMI message returned by IPMI command.
 538  * @handler_context: IPMI device context.
 539  */
 540 static acpi_status
 541 acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
 542                         u32 bits, acpi_integer *value,
 543                         void *handler_context, void *region_context)
 544 {
 545         struct acpi_ipmi_msg *tx_msg;
 546         struct acpi_ipmi_device *ipmi_device;
 547         int err;
 548         acpi_status status;
 549         unsigned long flags;
 550
 551         /*
 552          * IPMI opregion message.
 553          * IPMI message is firstly written to the BMC and system software
 554          * can get the respsonse. So it is unmeaningful for the read access
 555          * of IPMI opregion.
 556          */
 557         if ((function & ACPI_IO_MASK) == ACPI_READ)
 558                 return AE_TYPE;
 559
 560         tx_msg = ipmi_msg_alloc();
 561         if (!tx_msg)
 562                 return AE_NOT_EXIST;
 563         ipmi_device = tx_msg->device;
 564
 565         if (acpi_format_ipmi_request(tx_msg, address, value) != 0) {
 566                 ipmi_msg_release(tx_msg);
 567                 return AE_TYPE;
 568         }
 569
 570         acpi_ipmi_msg_get(tx_msg);
 571         mutex_lock(&driver_data.ipmi_lock);
 572         /* Do not add a tx_msg that can not be flushed. */
 573         if (ipmi_device->dead) {
 574                 mutex_unlock(&driver_data.ipmi_lock);
 575                 ipmi_msg_release(tx_msg);
 576                 return AE_NOT_EXIST;
 577         }
 578         spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
 579         list_add_tail(&tx_msg->head, &ipmi_device->tx_msg_list);
 580         spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
 581         mutex_unlock(&driver_data.ipmi_lock);
 582
 583         err = ipmi_request_settime(ipmi_device->user_interface,
 584                                    &tx_msg->addr,
 585                                    tx_msg->tx_msgid,
 586                                    &tx_msg->tx_message,
 587                                    NULL, 0, 0, IPMI_TIMEOUT);
 588         if (err) {
 589                 status = AE_ERROR;
 590                 goto out_msg;
 591         }
 592         wait_for_completion(&tx_msg->tx_complete);
 593
 594         acpi_format_ipmi_response(tx_msg, value);
 595         status = AE_OK;
 596
 597 out_msg:
 598         ipmi_cancel_tx_msg(ipmi_device, tx_msg);
 599         acpi_ipmi_msg_put(tx_msg);
 600         return status;
 601 }
 602
 603 static int __init acpi_ipmi_init(void)
 604 {
 605         int result;
 606         acpi_status status;
 607
 608         if (acpi_disabled)
 609                 return 0;
 610
 611         status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
 612                                                     ACPI_ADR_SPACE_IPMI,
 613                                                     &acpi_ipmi_space_handler,
 614                                                     NULL, NULL);
 615         if (ACPI_FAILURE(status)) {
 616                 pr_warn("Can't register IPMI opregion space handle\n");
 617                 return -EINVAL;
 618         }
 619         result = ipmi_smi_watcher_register(&driver_data.bmc_events);
 620         if (result)
 621                 pr_err("Can't register IPMI system interface watcher\n");
 622
 623         return result;
 624 }
 625
 626 static void __exit acpi_ipmi_exit(void)
 627 {
 628         struct acpi_ipmi_device *ipmi_device;
 629
 630         if (acpi_disabled)
 631                 return;
 632
 633         ipmi_smi_watcher_unregister(&driver_data.bmc_events);
 634
 635         /*
 636          * When one smi_watcher is unregistered, it is only deleted
 637          * from the smi_watcher list. But the smi_gone callback function
 638          * is not called. So explicitly uninstall the ACPI IPMI oregion
 639          * handler and free it.
 640          */
 641         mutex_lock(&driver_data.ipmi_lock);
 642         while (!list_empty(&driver_data.ipmi_devices)) {
 643                 ipmi_device = list_first_entry(&driver_data.ipmi_devices,
 644                                                struct acpi_ipmi_device,
 645                                                head);
 646                 __ipmi_dev_kill(ipmi_device);
 647                 mutex_unlock(&driver_data.ipmi_lock);
 648
 649                 ipmi_flush_tx_msg(ipmi_device);
 650                 acpi_ipmi_dev_put(ipmi_device);
 651
 652                 mutex_lock(&driver_data.ipmi_lock);
 653         }
 654         mutex_unlock(&driver_data.ipmi_lock);
 655         acpi_remove_address_space_handler(ACPI_ROOT_OBJECT,
 656                                           ACPI_ADR_SPACE_IPMI,
 657                                           &acpi_ipmi_space_handler);
 658 }
 659
 660 module_init(acpi_ipmi_init);
 661 module_exit(acpi_ipmi_exit);