drivers/i2c/i2c-core-acpi.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Linux I2C core ACPI support code
   4  *
   5  * Copyright (C) 2014 Intel Corp, Author: Lan Tianyu <[email protected]>
   6  */
   7
   8 #include <linux/acpi.h>
   9 #include <linux/device.h>
  10 #include <linux/err.h>
  11 #include <linux/i2c.h>
  12 #include <linux/list.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15
  16 #include "i2c-core.h"
  17
  18 struct i2c_acpi_handler_data {
  19         struct acpi_connection_info info;
  20         struct i2c_adapter *adapter;
  21 };
  22
  23 struct gsb_buffer {
  24         u8      status;
  25         u8      len;
  26         union {
  27                 u16     wdata;
  28                 u8      bdata;
  29                 u8      data[0];
  30         };
  31 } __packed;
  32
  33 struct i2c_acpi_lookup {
  34         struct i2c_board_info *info;
  35         acpi_handle adapter_handle;
  36         acpi_handle device_handle;
  37         acpi_handle search_handle;
  38         int n;
  39         int index;
  40         u32 speed;
  41         u32 min_speed;
  42 };
  43
  44 /**
  45  * i2c_acpi_get_i2c_resource - Gets I2cSerialBus resource if type matches
  46  * @ares:       ACPI resource
  47  * @i2c:        Pointer to I2cSerialBus resource will be returned here
  48  *
  49  * Checks if the given ACPI resource is of type I2cSerialBus.
  50  * In this case, returns a pointer to it to the caller.
  51  *
  52  * Returns true if resource type is of I2cSerialBus, otherwise false.
  53  */
  54 bool i2c_acpi_get_i2c_resource(struct acpi_resource *ares,
  55                                struct acpi_resource_i2c_serialbus **i2c)
  56 {
  57         struct acpi_resource_i2c_serialbus *sb;
  58
  59         if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
  60                 return false;
  61
  62         sb = &ares->data.i2c_serial_bus;
  63         if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
  64                 return false;
  65
  66         *i2c = sb;
  67         return true;
  68 }
  69 EXPORT_SYMBOL_GPL(i2c_acpi_get_i2c_resource);
  70
  71 static int i2c_acpi_fill_info(struct acpi_resource *ares, void *data)
  72 {
  73         struct i2c_acpi_lookup *lookup = data;
  74         struct i2c_board_info *info = lookup->info;
  75         struct acpi_resource_i2c_serialbus *sb;
  76         acpi_status status;
  77
  78         if (info->addr || !i2c_acpi_get_i2c_resource(ares, &sb))
  79                 return 1;
  80
  81         if (lookup->index != -1 && lookup->n++ != lookup->index)
  82                 return 1;
  83
  84         status = acpi_get_handle(lookup->device_handle,
  85                                  sb->resource_source.string_ptr,
  86                                  &lookup->adapter_handle);
  87         if (ACPI_FAILURE(status))
  88                 return 1;
  89
  90         info->addr = sb->slave_address;
  91         lookup->speed = sb->connection_speed;
  92         if (sb->access_mode == ACPI_I2C_10BIT_MODE)
  93                 info->flags |= I2C_CLIENT_TEN;
  94
  95         return 1;
  96 }
  97
  98 static const struct acpi_device_id i2c_acpi_ignored_device_ids[] = {
  99         /*
 100          * ACPI video acpi_devices, which are handled by the acpi-video driver
 101          * sometimes contain a SERIAL_TYPE_I2C ACPI resource, ignore these.
 102          */
 103         { ACPI_VIDEO_HID, 0 },
 104         {}
 105 };
 106
 107 static int i2c_acpi_do_lookup(struct acpi_device *adev,
 108                               struct i2c_acpi_lookup *lookup)
 109 {
 110         struct i2c_board_info *info = lookup->info;
 111         struct list_head resource_list;
 112         int ret;
 113
 114         if (acpi_bus_get_status(adev) || !adev->status.present)
 115                 return -EINVAL;
 116
 117         if (acpi_match_device_ids(adev, i2c_acpi_ignored_device_ids) == 0)
 118                 return -ENODEV;
 119
 120         memset(info, 0, sizeof(*info));
 121         lookup->device_handle = acpi_device_handle(adev);
 122
 123         /* Look up for I2cSerialBus resource */
 124         INIT_LIST_HEAD(&resource_list);
 125         ret = acpi_dev_get_resources(adev, &resource_list,
 126                                      i2c_acpi_fill_info, lookup);
 127         acpi_dev_free_resource_list(&resource_list);
 128
 129         if (ret < 0 || !info->addr)
 130                 return -EINVAL;
 131
 132         return 0;
 133 }
 134
 135 static int i2c_acpi_add_resource(struct acpi_resource *ares, void *data)
 136 {
 137         int *irq = data;
 138         struct resource r;
 139
 140         if (*irq <= 0 && acpi_dev_resource_interrupt(ares, 0, &r))
 141                 *irq = i2c_dev_irq_from_resources(&r, 1);
 142
 143         return 1; /* No need to add resource to the list */
 144 }
 145
 146 /**
 147  * i2c_acpi_get_irq - get device IRQ number from ACPI
 148  * @client: Pointer to the I2C client device
 149  *
 150  * Find the IRQ number used by a specific client device.
 151  *
 152  * Return: The IRQ number or an error code.
 153  */
 154 int i2c_acpi_get_irq(struct i2c_client *client)
 155 {
 156         struct acpi_device *adev = ACPI_COMPANION(&client->dev);
 157         struct list_head resource_list;
 158         int irq = -ENOENT;
 159         int ret;
 160
 161         INIT_LIST_HEAD(&resource_list);
 162
 163         ret = acpi_dev_get_resources(adev, &resource_list,
 164                                      i2c_acpi_add_resource, &irq);
 165         if (ret < 0)
 166                 return ret;
 167
 168         acpi_dev_free_resource_list(&resource_list);
 169
 170         if (irq == -ENOENT)
 171                 irq = acpi_dev_gpio_irq_get(adev, 0);
 172
 173         return irq;
 174 }
 175
 176 static int i2c_acpi_get_info(struct acpi_device *adev,
 177                              struct i2c_board_info *info,
 178                              struct i2c_adapter *adapter,
 179                              acpi_handle *adapter_handle)
 180 {
 181         struct i2c_acpi_lookup lookup;
 182         int ret;
 183
 184         memset(&lookup, 0, sizeof(lookup));
 185         lookup.info = info;
 186         lookup.index = -1;
 187
 188         if (acpi_device_enumerated(adev))
 189                 return -EINVAL;
 190
 191         ret = i2c_acpi_do_lookup(adev, &lookup);
 192         if (ret)
 193                 return ret;
 194
 195         if (adapter) {
 196                 /* The adapter must match the one in I2cSerialBus() connector */
 197                 if (ACPI_HANDLE(&adapter->dev) != lookup.adapter_handle)
 198                         return -ENODEV;
 199         } else {
 200                 struct acpi_device *adapter_adev;
 201
 202                 /* The adapter must be present */
 203                 if (acpi_bus_get_device(lookup.adapter_handle, &adapter_adev))
 204                         return -ENODEV;
 205                 if (acpi_bus_get_status(adapter_adev) ||
 206                     !adapter_adev->status.present)
 207                         return -ENODEV;
 208         }
 209
 210         info->fwnode = acpi_fwnode_handle(adev);
 211         if (adapter_handle)
 212                 *adapter_handle = lookup.adapter_handle;
 213
 214         acpi_set_modalias(adev, dev_name(&adev->dev), info->type,
 215                           sizeof(info->type));
 216
 217         return 0;
 218 }
 219
 220 static void i2c_acpi_register_device(struct i2c_adapter *adapter,
 221                                      struct acpi_device *adev,
 222                                      struct i2c_board_info *info)
 223 {
 224         adev->power.flags.ignore_parent = true;
 225         acpi_device_set_enumerated(adev);
 226
 227         if (!i2c_new_device(adapter, info)) {
 228                 adev->power.flags.ignore_parent = false;
 229                 dev_err(&adapter->dev,
 230                         "failed to add I2C device %s from ACPI\n",
 231                         dev_name(&adev->dev));
 232         }
 233 }
 234
 235 static acpi_status i2c_acpi_add_device(acpi_handle handle, u32 level,
 236                                        void *data, void **return_value)
 237 {
 238         struct i2c_adapter *adapter = data;
 239         struct acpi_device *adev;
 240         struct i2c_board_info info;
 241
 242         if (acpi_bus_get_device(handle, &adev))
 243                 return AE_OK;
 244
 245         if (i2c_acpi_get_info(adev, &info, adapter, NULL))
 246                 return AE_OK;
 247
 248         i2c_acpi_register_device(adapter, adev, &info);
 249
 250         return AE_OK;
 251 }
 252
 253 #define I2C_ACPI_MAX_SCAN_DEPTH 32
 254
 255 /**
 256  * i2c_acpi_register_devices - enumerate I2C slave devices behind adapter
 257  * @adap: pointer to adapter
 258  *
 259  * Enumerate all I2C slave devices behind this adapter by walking the ACPI
 260  * namespace. When a device is found it will be added to the Linux device
 261  * model and bound to the corresponding ACPI handle.
 262  */
 263 void i2c_acpi_register_devices(struct i2c_adapter *adap)
 264 {
 265         acpi_status status;
 266
 267         if (!has_acpi_companion(&adap->dev))
 268                 return;
 269
 270         status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 271                                      I2C_ACPI_MAX_SCAN_DEPTH,
 272                                      i2c_acpi_add_device, NULL,
 273                                      adap, NULL);
 274         if (ACPI_FAILURE(status))
 275                 dev_warn(&adap->dev, "failed to enumerate I2C slaves\n");
 276 }
 277
 278 const struct acpi_device_id *
 279 i2c_acpi_match_device(const struct acpi_device_id *matches,
 280                       struct i2c_client *client)
 281 {
 282         if (!(client && matches))
 283                 return NULL;
 284
 285         return acpi_match_device(matches, &client->dev);
 286 }
 287
 288 static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
 289                                            void *data, void **return_value)
 290 {
 291         struct i2c_acpi_lookup *lookup = data;
 292         struct acpi_device *adev;
 293
 294         if (acpi_bus_get_device(handle, &adev))
 295                 return AE_OK;
 296
 297         if (i2c_acpi_do_lookup(adev, lookup))
 298                 return AE_OK;
 299
 300         if (lookup->search_handle != lookup->adapter_handle)
 301                 return AE_OK;
 302
 303         if (lookup->speed <= lookup->min_speed)
 304                 lookup->min_speed = lookup->speed;
 305
 306         return AE_OK;
 307 }
 308
 309 /**
 310  * i2c_acpi_find_bus_speed - find I2C bus speed from ACPI
 311  * @dev: The device owning the bus
 312  *
 313  * Find the I2C bus speed by walking the ACPI namespace for all I2C slaves
 314  * devices connected to this bus and use the speed of slowest device.
 315  *
 316  * Returns the speed in Hz or zero
 317  */
 318 u32 i2c_acpi_find_bus_speed(struct device *dev)
 319 {
 320         struct i2c_acpi_lookup lookup;
 321         struct i2c_board_info dummy;
 322         acpi_status status;
 323
 324         if (!has_acpi_companion(dev))
 325                 return 0;
 326
 327         memset(&lookup, 0, sizeof(lookup));
 328         lookup.search_handle = ACPI_HANDLE(dev);
 329         lookup.min_speed = UINT_MAX;
 330         lookup.info = &dummy;
 331         lookup.index = -1;
 332
 333         status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 334                                      I2C_ACPI_MAX_SCAN_DEPTH,
 335                                      i2c_acpi_lookup_speed, NULL,
 336                                      &lookup, NULL);
 337
 338         if (ACPI_FAILURE(status)) {
 339                 dev_warn(dev, "unable to find I2C bus speed from ACPI\n");
 340                 return 0;
 341         }
 342
 343         return lookup.min_speed != UINT_MAX ? lookup.min_speed : 0;
 344 }
 345 EXPORT_SYMBOL_GPL(i2c_acpi_find_bus_speed);
 346
 347 static int i2c_acpi_find_match_adapter(struct device *dev, const void *data)
 348 {
 349         struct i2c_adapter *adapter = i2c_verify_adapter(dev);
 350
 351         if (!adapter)
 352                 return 0;
 353
 354         return ACPI_HANDLE(dev) == (acpi_handle)data;
 355 }
 356
 357 struct i2c_adapter *i2c_acpi_find_adapter_by_handle(acpi_handle handle)
 358 {
 359         struct device *dev;
 360
 361         dev = bus_find_device(&i2c_bus_type, NULL, handle,
 362                               i2c_acpi_find_match_adapter);
 363
 364         return dev ? i2c_verify_adapter(dev) : NULL;
 365 }
 366 EXPORT_SYMBOL_GPL(i2c_acpi_find_adapter_by_handle);
 367
 368 static struct i2c_client *i2c_acpi_find_client_by_adev(struct acpi_device *adev)
 369 {
 370         struct device *dev;
 371
 372         dev = bus_find_device_by_acpi_dev(&i2c_bus_type, adev);
 373         return dev ? i2c_verify_client(dev) : NULL;
 374 }
 375
 376 static int i2c_acpi_notify(struct notifier_block *nb, unsigned long value,
 377                            void *arg)
 378 {
 379         struct acpi_device *adev = arg;
 380         struct i2c_board_info info;
 381         acpi_handle adapter_handle;
 382         struct i2c_adapter *adapter;
 383         struct i2c_client *client;
 384
 385         switch (value) {
 386         case ACPI_RECONFIG_DEVICE_ADD:
 387                 if (i2c_acpi_get_info(adev, &info, NULL, &adapter_handle))
 388                         break;
 389
 390                 adapter = i2c_acpi_find_adapter_by_handle(adapter_handle);
 391                 if (!adapter)
 392                         break;
 393
 394                 i2c_acpi_register_device(adapter, adev, &info);
 395                 break;
 396         case ACPI_RECONFIG_DEVICE_REMOVE:
 397                 if (!acpi_device_enumerated(adev))
 398                         break;
 399
 400                 client = i2c_acpi_find_client_by_adev(adev);
 401                 if (!client)
 402                         break;
 403
 404                 i2c_unregister_device(client);
 405                 put_device(&client->dev);
 406                 break;
 407         }
 408
 409         return NOTIFY_OK;
 410 }
 411
 412 struct notifier_block i2c_acpi_notifier = {
 413         .notifier_call = i2c_acpi_notify,
 414 };
 415
 416 /**
 417  * i2c_acpi_new_device - Create i2c-client for the Nth I2cSerialBus resource
 418  * @dev:     Device owning the ACPI resources to get the client from
 419  * @index:   Index of ACPI resource to get
 420  * @info:    describes the I2C device; note this is modified (addr gets set)
 421  * Context: can sleep
 422  *
 423  * By default the i2c subsys creates an i2c-client for the first I2cSerialBus
 424  * resource of an acpi_device, but some acpi_devices have multiple I2cSerialBus
 425  * resources, in that case this function can be used to create an i2c-client
 426  * for other I2cSerialBus resources in the Current Resource Settings table.
 427  *
 428  * Also see i2c_new_device, which this function calls to create the i2c-client.
 429  *
 430  * Returns a pointer to the new i2c-client, or error pointer in case of failure.
 431  * Specifically, -EPROBE_DEFER is returned if the adapter is not found.
 432  */
 433 struct i2c_client *i2c_acpi_new_device(struct device *dev, int index,
 434                                        struct i2c_board_info *info)
 435 {
 436         struct i2c_acpi_lookup lookup;
 437         struct i2c_adapter *adapter;
 438         struct i2c_client *client;
 439         struct acpi_device *adev;
 440         LIST_HEAD(resource_list);
 441         int ret;
 442
 443         adev = ACPI_COMPANION(dev);
 444         if (!adev)
 445                 return ERR_PTR(-EINVAL);
 446
 447         memset(&lookup, 0, sizeof(lookup));
 448         lookup.info = info;
 449         lookup.device_handle = acpi_device_handle(adev);
 450         lookup.index = index;
 451
 452         ret = acpi_dev_get_resources(adev, &resource_list,
 453                                      i2c_acpi_fill_info, &lookup);
 454         if (ret < 0)
 455                 return ERR_PTR(ret);
 456
 457         acpi_dev_free_resource_list(&resource_list);
 458
 459         if (!info->addr)
 460                 return ERR_PTR(-EADDRNOTAVAIL);
 461
 462         adapter = i2c_acpi_find_adapter_by_handle(lookup.adapter_handle);
 463         if (!adapter)
 464                 return ERR_PTR(-EPROBE_DEFER);
 465
 466         client = i2c_new_device(adapter, info);
 467         if (!client)
 468                 return ERR_PTR(-ENODEV);
 469
 470         return client;
 471 }
 472 EXPORT_SYMBOL_GPL(i2c_acpi_new_device);
 473
 474 #ifdef CONFIG_ACPI_I2C_OPREGION
 475 static int acpi_gsb_i2c_read_bytes(struct i2c_client *client,
 476                 u8 cmd, u8 *data, u8 data_len)
 477 {
 478
 479         struct i2c_msg msgs[2];
 480         int ret;
 481         u8 *buffer;
 482
 483         buffer = kzalloc(data_len, GFP_KERNEL);
 484         if (!buffer)
 485                 return AE_NO_MEMORY;
 486
 487         msgs[0].addr = client->addr;
 488         msgs[0].flags = client->flags;
 489         msgs[0].len = 1;
 490         msgs[0].buf = &cmd;
 491
 492         msgs[1].addr = client->addr;
 493         msgs[1].flags = client->flags | I2C_M_RD;
 494         msgs[1].len = data_len;
 495         msgs[1].buf = buffer;
 496
 497         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 498         if (ret < 0) {
 499                 /* Getting a NACK is unfortunately normal with some DSTDs */
 500                 if (ret == -EREMOTEIO)
 501                         dev_dbg(&client->adapter->dev, "i2c read %d bytes from client@%#x starting at reg %#x failed, error: %d\n",
 502                                 data_len, client->addr, cmd, ret);
 503                 else
 504                         dev_err(&client->adapter->dev, "i2c read %d bytes from client@%#x starting at reg %#x failed, error: %d\n",
 505                                 data_len, client->addr, cmd, ret);
 506         /* 2 transfers must have completed successfully */
 507         } else if (ret == 2) {
 508                 memcpy(data, buffer, data_len);
 509                 ret = 0;
 510         } else {
 511                 ret = -EIO;
 512         }
 513
 514         kfree(buffer);
 515         return ret;
 516 }
 517
 518 static int acpi_gsb_i2c_write_bytes(struct i2c_client *client,
 519                 u8 cmd, u8 *data, u8 data_len)
 520 {
 521
 522         struct i2c_msg msgs[1];
 523         u8 *buffer;
 524         int ret = AE_OK;
 525
 526         buffer = kzalloc(data_len + 1, GFP_KERNEL);
 527         if (!buffer)
 528                 return AE_NO_MEMORY;
 529
 530         buffer[0] = cmd;
 531         memcpy(buffer + 1, data, data_len);
 532
 533         msgs[0].addr = client->addr;
 534         msgs[0].flags = client->flags;
 535         msgs[0].len = data_len + 1;
 536         msgs[0].buf = buffer;
 537
 538         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 539
 540         kfree(buffer);
 541
 542         if (ret < 0) {
 543                 dev_err(&client->adapter->dev, "i2c write failed: %d\n", ret);
 544                 return ret;
 545         }
 546
 547         /* 1 transfer must have completed successfully */
 548         return (ret == 1) ? 0 : -EIO;
 549 }
 550
 551 static acpi_status
 552 i2c_acpi_space_handler(u32 function, acpi_physical_address command,
 553                         u32 bits, u64 *value64,
 554                         void *handler_context, void *region_context)
 555 {
 556         struct gsb_buffer *gsb = (struct gsb_buffer *)value64;
 557         struct i2c_acpi_handler_data *data = handler_context;
 558         struct acpi_connection_info *info = &data->info;
 559         struct acpi_resource_i2c_serialbus *sb;
 560         struct i2c_adapter *adapter = data->adapter;
 561         struct i2c_client *client;
 562         struct acpi_resource *ares;
 563         u32 accessor_type = function >> 16;
 564         u8 action = function & ACPI_IO_MASK;
 565         acpi_status ret;
 566         int status;
 567
 568         ret = acpi_buffer_to_resource(info->connection, info->length, &ares);
 569         if (ACPI_FAILURE(ret))
 570                 return ret;
 571
 572         client = kzalloc(sizeof(*client), GFP_KERNEL);
 573         if (!client) {
 574                 ret = AE_NO_MEMORY;
 575                 goto err;
 576         }
 577
 578         if (!value64 || !i2c_acpi_get_i2c_resource(ares, &sb)) {
 579                 ret = AE_BAD_PARAMETER;
 580                 goto err;
 581         }
 582
 583         client->adapter = adapter;
 584         client->addr = sb->slave_address;
 585
 586         if (sb->access_mode == ACPI_I2C_10BIT_MODE)
 587                 client->flags |= I2C_CLIENT_TEN;
 588
 589         switch (accessor_type) {
 590         case ACPI_GSB_ACCESS_ATTRIB_SEND_RCV:
 591                 if (action == ACPI_READ) {
 592                         status = i2c_smbus_read_byte(client);
 593                         if (status >= 0) {
 594                                 gsb->bdata = status;
 595                                 status = 0;
 596                         }
 597                 } else {
 598                         status = i2c_smbus_write_byte(client, gsb->bdata);
 599                 }
 600                 break;
 601
 602         case ACPI_GSB_ACCESS_ATTRIB_BYTE:
 603                 if (action == ACPI_READ) {
 604                         status = i2c_smbus_read_byte_data(client, command);
 605                         if (status >= 0) {
 606                                 gsb->bdata = status;
 607                                 status = 0;
 608                         }
 609                 } else {
 610                         status = i2c_smbus_write_byte_data(client, command,
 611                                         gsb->bdata);
 612                 }
 613                 break;
 614
 615         case ACPI_GSB_ACCESS_ATTRIB_WORD:
 616                 if (action == ACPI_READ) {
 617                         status = i2c_smbus_read_word_data(client, command);
 618                         if (status >= 0) {
 619                                 gsb->wdata = status;
 620                                 status = 0;
 621                         }
 622                 } else {
 623                         status = i2c_smbus_write_word_data(client, command,
 624                                         gsb->wdata);
 625                 }
 626                 break;
 627
 628         case ACPI_GSB_ACCESS_ATTRIB_BLOCK:
 629                 if (action == ACPI_READ) {
 630                         status = i2c_smbus_read_block_data(client, command,
 631                                         gsb->data);
 632                         if (status >= 0) {
 633                                 gsb->len = status;
 634                                 status = 0;
 635                         }
 636                 } else {
 637                         status = i2c_smbus_write_block_data(client, command,
 638                                         gsb->len, gsb->data);
 639                 }
 640                 break;
 641
 642         case ACPI_GSB_ACCESS_ATTRIB_MULTIBYTE:
 643                 if (action == ACPI_READ) {
 644                         status = acpi_gsb_i2c_read_bytes(client, command,
 645                                         gsb->data, info->access_length);
 646                 } else {
 647                         status = acpi_gsb_i2c_write_bytes(client, command,
 648                                         gsb->data, info->access_length);
 649                 }
 650                 break;
 651
 652         default:
 653                 dev_warn(&adapter->dev, "protocol 0x%02x not supported for client 0x%02x\n",
 654                          accessor_type, client->addr);
 655                 ret = AE_BAD_PARAMETER;
 656                 goto err;
 657         }
 658
 659         gsb->status = status;
 660
 661  err:
 662         kfree(client);
 663         ACPI_FREE(ares);
 664         return ret;
 665 }
 666
 667
 668 int i2c_acpi_install_space_handler(struct i2c_adapter *adapter)
 669 {
 670         acpi_handle handle;
 671         struct i2c_acpi_handler_data *data;
 672         acpi_status status;
 673
 674         if (!adapter->dev.parent)
 675                 return -ENODEV;
 676
 677         handle = ACPI_HANDLE(adapter->dev.parent);
 678
 679         if (!handle)
 680                 return -ENODEV;
 681
 682         data = kzalloc(sizeof(struct i2c_acpi_handler_data),
 683                             GFP_KERNEL);
 684         if (!data)
 685                 return -ENOMEM;
 686
 687         data->adapter = adapter;
 688         status = acpi_bus_attach_private_data(handle, (void *)data);
 689         if (ACPI_FAILURE(status)) {
 690                 kfree(data);
 691                 return -ENOMEM;
 692         }
 693
 694         status = acpi_install_address_space_handler(handle,
 695                                 ACPI_ADR_SPACE_GSBUS,
 696                                 &i2c_acpi_space_handler,
 697                                 NULL,
 698                                 data);
 699         if (ACPI_FAILURE(status)) {
 700                 dev_err(&adapter->dev, "Error installing i2c space handler\n");
 701                 acpi_bus_detach_private_data(handle);
 702                 kfree(data);
 703                 return -ENOMEM;
 704         }
 705
 706         acpi_walk_dep_device_list(handle);
 707         return 0;
 708 }
 709
 710 void i2c_acpi_remove_space_handler(struct i2c_adapter *adapter)
 711 {
 712         acpi_handle handle;
 713         struct i2c_acpi_handler_data *data;
 714         acpi_status status;
 715
 716         if (!adapter->dev.parent)
 717                 return;
 718
 719         handle = ACPI_HANDLE(adapter->dev.parent);
 720
 721         if (!handle)
 722                 return;
 723
 724         acpi_remove_address_space_handler(handle,
 725                                 ACPI_ADR_SPACE_GSBUS,
 726                                 &i2c_acpi_space_handler);
 727
 728         status = acpi_bus_get_private_data(handle, (void **)&data);
 729         if (ACPI_SUCCESS(status))
 730                 kfree(data);
 731
 732         acpi_bus_detach_private_data(handle);
 733 }
 734 #endif /* CONFIG_ACPI_I2C_OPREGION */