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