drivers/tty/serdev/core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2016-2017 Linaro Ltd., Rob Herring <robh@kernel.org>
   4  *
   5  * Based on drivers/spmi/spmi.c:
   6  * Copyright (c) 2012-2015, The Linux Foundation. All rights reserved.
   7  */
   8
   9 #include <linux/acpi.h>
  10 #include <linux/errno.h>
  11 #include <linux/idr.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/of.h>
  15 #include <linux/of_device.h>
  16 #include <linux/pm_domain.h>
  17 #include <linux/pm_runtime.h>
  18 #include <linux/sched.h>
  19 #include <linux/serdev.h>
  20 #include <linux/slab.h>
  21 #include <linux/platform_data/x86/apple.h>
  22
  23 static bool is_registered;
  24 static DEFINE_IDA(ctrl_ida);
  25
  26 static ssize_t modalias_show(struct device *dev,
  27                              struct device_attribute *attr, char *buf)
  28 {
  29         int len;
  30
  31         len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
  32         if (len != -ENODEV)
  33                 return len;
  34
  35         return of_device_modalias(dev, buf, PAGE_SIZE);
  36 }
  37 static DEVICE_ATTR_RO(modalias);
  38
  39 static struct attribute *serdev_device_attrs[] = {
  40         &dev_attr_modalias.attr,
  41         NULL,
  42 };
  43 ATTRIBUTE_GROUPS(serdev_device);
  44
  45 static int serdev_device_uevent(struct device *dev, struct kobj_uevent_env *env)
  46 {
  47         int rc;
  48
  49         /* TODO: platform modalias */
  50
  51         rc = acpi_device_uevent_modalias(dev, env);
  52         if (rc != -ENODEV)
  53                 return rc;
  54
  55         return of_device_uevent_modalias(dev, env);
  56 }
  57
  58 static void serdev_device_release(struct device *dev)
  59 {
  60         struct serdev_device *serdev = to_serdev_device(dev);
  61         kfree(serdev);
  62 }
  63
  64 static const struct device_type serdev_device_type = {
  65         .groups         = serdev_device_groups,
  66         .uevent         = serdev_device_uevent,
  67         .release        = serdev_device_release,
  68 };
  69
  70 static bool is_serdev_device(const struct device *dev)
  71 {
  72         return dev->type == &serdev_device_type;
  73 }
  74
  75 static void serdev_ctrl_release(struct device *dev)
  76 {
  77         struct serdev_controller *ctrl = to_serdev_controller(dev);
  78         ida_simple_remove(&ctrl_ida, ctrl->nr);
  79         kfree(ctrl);
  80 }
  81
  82 static const struct device_type serdev_ctrl_type = {
  83         .release        = serdev_ctrl_release,
  84 };
  85
  86 static int serdev_device_match(struct device *dev, struct device_driver *drv)
  87 {
  88         if (!is_serdev_device(dev))
  89                 return 0;
  90
  91         /* TODO: platform matching */
  92         if (acpi_driver_match_device(dev, drv))
  93                 return 1;
  94
  95         return of_driver_match_device(dev, drv);
  96 }
  97
  98 /**
  99  * serdev_device_add() - add a device previously constructed via serdev_device_alloc()
 100  * @serdev:     serdev_device to be added
 101  */
 102 int serdev_device_add(struct serdev_device *serdev)
 103 {
 104         struct serdev_controller *ctrl = serdev->ctrl;
 105         struct device *parent = serdev->dev.parent;
 106         int err;
 107
 108         dev_set_name(&serdev->dev, "%s-%d", dev_name(parent), serdev->nr);
 109
 110         /* Only a single slave device is currently supported. */
 111         if (ctrl->serdev) {
 112                 dev_err(&serdev->dev, "controller busy\n");
 113                 return -EBUSY;
 114         }
 115         ctrl->serdev = serdev;
 116
 117         err = device_add(&serdev->dev);
 118         if (err < 0) {
 119                 dev_err(&serdev->dev, "Can't add %s, status %pe\n",
 120                         dev_name(&serdev->dev), ERR_PTR(err));
 121                 goto err_clear_serdev;
 122         }
 123
 124         dev_dbg(&serdev->dev, "device %s registered\n", dev_name(&serdev->dev));
 125
 126         return 0;
 127
 128 err_clear_serdev:
 129         ctrl->serdev = NULL;
 130         return err;
 131 }
 132 EXPORT_SYMBOL_GPL(serdev_device_add);
 133
 134 /**
 135  * serdev_device_remove(): remove an serdev device
 136  * @serdev:     serdev_device to be removed
 137  */
 138 void serdev_device_remove(struct serdev_device *serdev)
 139 {
 140         struct serdev_controller *ctrl = serdev->ctrl;
 141
 142         device_unregister(&serdev->dev);
 143         ctrl->serdev = NULL;
 144 }
 145 EXPORT_SYMBOL_GPL(serdev_device_remove);
 146
 147 int serdev_device_open(struct serdev_device *serdev)
 148 {
 149         struct serdev_controller *ctrl = serdev->ctrl;
 150         int ret;
 151
 152         if (!ctrl || !ctrl->ops->open)
 153                 return -EINVAL;
 154
 155         ret = ctrl->ops->open(ctrl);
 156         if (ret)
 157                 return ret;
 158
 159         ret = pm_runtime_get_sync(&ctrl->dev);
 160         if (ret < 0) {
 161                 pm_runtime_put_noidle(&ctrl->dev);
 162                 goto err_close;
 163         }
 164
 165         return 0;
 166
 167 err_close:
 168         if (ctrl->ops->close)
 169                 ctrl->ops->close(ctrl);
 170
 171         return ret;
 172 }
 173 EXPORT_SYMBOL_GPL(serdev_device_open);
 174
 175 void serdev_device_close(struct serdev_device *serdev)
 176 {
 177         struct serdev_controller *ctrl = serdev->ctrl;
 178
 179         if (!ctrl || !ctrl->ops->close)
 180                 return;
 181
 182         pm_runtime_put(&ctrl->dev);
 183
 184         ctrl->ops->close(ctrl);
 185 }
 186 EXPORT_SYMBOL_GPL(serdev_device_close);
 187
 188 static void devm_serdev_device_release(struct device *dev, void *dr)
 189 {
 190         serdev_device_close(*(struct serdev_device **)dr);
 191 }
 192
 193 int devm_serdev_device_open(struct device *dev, struct serdev_device *serdev)
 194 {
 195         struct serdev_device **dr;
 196         int ret;
 197
 198         dr = devres_alloc(devm_serdev_device_release, sizeof(*dr), GFP_KERNEL);
 199         if (!dr)
 200                 return -ENOMEM;
 201
 202         ret = serdev_device_open(serdev);
 203         if (ret) {
 204                 devres_free(dr);
 205                 return ret;
 206         }
 207
 208         *dr = serdev;
 209         devres_add(dev, dr);
 210
 211         return 0;
 212 }
 213 EXPORT_SYMBOL_GPL(devm_serdev_device_open);
 214
 215 void serdev_device_write_wakeup(struct serdev_device *serdev)
 216 {
 217         complete(&serdev->write_comp);
 218 }
 219 EXPORT_SYMBOL_GPL(serdev_device_write_wakeup);
 220
 221 /**
 222  * serdev_device_write_buf() - write data asynchronously
 223  * @serdev:     serdev device
 224  * @buf:        data to be written
 225  * @count:      number of bytes to write
 226  *
 227  * Write data to the device asynchronously.
 228  *
 229  * Note that any accepted data has only been buffered by the controller; use
 230  * serdev_device_wait_until_sent() to make sure the controller write buffer
 231  * has actually been emptied.
 232  *
 233  * Return: The number of bytes written (less than count if not enough room in
 234  * the write buffer), or a negative errno on errors.
 235  */
 236 int serdev_device_write_buf(struct serdev_device *serdev,
 237                             const unsigned char *buf, size_t count)
 238 {
 239         struct serdev_controller *ctrl = serdev->ctrl;
 240
 241         if (!ctrl || !ctrl->ops->write_buf)
 242                 return -EINVAL;
 243
 244         return ctrl->ops->write_buf(ctrl, buf, count);
 245 }
 246 EXPORT_SYMBOL_GPL(serdev_device_write_buf);
 247
 248 /**
 249  * serdev_device_write() - write data synchronously
 250  * @serdev:     serdev device
 251  * @buf:        data to be written
 252  * @count:      number of bytes to write
 253  * @timeout:    timeout in jiffies, or 0 to wait indefinitely
 254  *
 255  * Write data to the device synchronously by repeatedly calling
 256  * serdev_device_write() until the controller has accepted all data (unless
 257  * interrupted by a timeout or a signal).
 258  *
 259  * Note that any accepted data has only been buffered by the controller; use
 260  * serdev_device_wait_until_sent() to make sure the controller write buffer
 261  * has actually been emptied.
 262  *
 263  * Note that this function depends on serdev_device_write_wakeup() being
 264  * called in the serdev driver write_wakeup() callback.
 265  *
 266  * Return: The number of bytes written (less than count if interrupted),
 267  * -ETIMEDOUT or -ERESTARTSYS if interrupted before any bytes were written, or
 268  * a negative errno on errors.
 269  */
 270 int serdev_device_write(struct serdev_device *serdev,
 271                         const unsigned char *buf, size_t count,
 272                         long timeout)
 273 {
 274         struct serdev_controller *ctrl = serdev->ctrl;
 275         int written = 0;
 276         int ret;
 277
 278         if (!ctrl || !ctrl->ops->write_buf || !serdev->ops->write_wakeup)
 279                 return -EINVAL;
 280
 281         if (timeout == 0)
 282                 timeout = MAX_SCHEDULE_TIMEOUT;
 283
 284         mutex_lock(&serdev->write_lock);
 285         do {
 286                 reinit_completion(&serdev->write_comp);
 287
 288                 ret = ctrl->ops->write_buf(ctrl, buf, count);
 289                 if (ret < 0)
 290                         break;
 291
 292                 written += ret;
 293                 buf += ret;
 294                 count -= ret;
 295
 296                 if (count == 0)
 297                         break;
 298
 299                 timeout = wait_for_completion_interruptible_timeout(&serdev->write_comp,
 300                                                                     timeout);
 301         } while (timeout > 0);
 302         mutex_unlock(&serdev->write_lock);
 303
 304         if (ret < 0)
 305                 return ret;
 306
 307         if (timeout <= 0 && written == 0) {
 308                 if (timeout == -ERESTARTSYS)
 309                         return -ERESTARTSYS;
 310                 else
 311                         return -ETIMEDOUT;
 312         }
 313
 314         return written;
 315 }
 316 EXPORT_SYMBOL_GPL(serdev_device_write);
 317
 318 void serdev_device_write_flush(struct serdev_device *serdev)
 319 {
 320         struct serdev_controller *ctrl = serdev->ctrl;
 321
 322         if (!ctrl || !ctrl->ops->write_flush)
 323                 return;
 324
 325         ctrl->ops->write_flush(ctrl);
 326 }
 327 EXPORT_SYMBOL_GPL(serdev_device_write_flush);
 328
 329 int serdev_device_write_room(struct serdev_device *serdev)
 330 {
 331         struct serdev_controller *ctrl = serdev->ctrl;
 332
 333         if (!ctrl || !ctrl->ops->write_room)
 334                 return 0;
 335
 336         return serdev->ctrl->ops->write_room(ctrl);
 337 }
 338 EXPORT_SYMBOL_GPL(serdev_device_write_room);
 339
 340 unsigned int serdev_device_set_baudrate(struct serdev_device *serdev, unsigned int speed)
 341 {
 342         struct serdev_controller *ctrl = serdev->ctrl;
 343
 344         if (!ctrl || !ctrl->ops->set_baudrate)
 345                 return 0;
 346
 347         return ctrl->ops->set_baudrate(ctrl, speed);
 348
 349 }
 350 EXPORT_SYMBOL_GPL(serdev_device_set_baudrate);
 351
 352 void serdev_device_set_flow_control(struct serdev_device *serdev, bool enable)
 353 {
 354         struct serdev_controller *ctrl = serdev->ctrl;
 355
 356         if (!ctrl || !ctrl->ops->set_flow_control)
 357                 return;
 358
 359         ctrl->ops->set_flow_control(ctrl, enable);
 360 }
 361 EXPORT_SYMBOL_GPL(serdev_device_set_flow_control);
 362
 363 int serdev_device_set_parity(struct serdev_device *serdev,
 364                              enum serdev_parity parity)
 365 {
 366         struct serdev_controller *ctrl = serdev->ctrl;
 367
 368         if (!ctrl || !ctrl->ops->set_parity)
 369                 return -ENOTSUPP;
 370
 371         return ctrl->ops->set_parity(ctrl, parity);
 372 }
 373 EXPORT_SYMBOL_GPL(serdev_device_set_parity);
 374
 375 void serdev_device_wait_until_sent(struct serdev_device *serdev, long timeout)
 376 {
 377         struct serdev_controller *ctrl = serdev->ctrl;
 378
 379         if (!ctrl || !ctrl->ops->wait_until_sent)
 380                 return;
 381
 382         ctrl->ops->wait_until_sent(ctrl, timeout);
 383 }
 384 EXPORT_SYMBOL_GPL(serdev_device_wait_until_sent);
 385
 386 int serdev_device_get_tiocm(struct serdev_device *serdev)
 387 {
 388         struct serdev_controller *ctrl = serdev->ctrl;
 389
 390         if (!ctrl || !ctrl->ops->get_tiocm)
 391                 return -ENOTSUPP;
 392
 393         return ctrl->ops->get_tiocm(ctrl);
 394 }
 395 EXPORT_SYMBOL_GPL(serdev_device_get_tiocm);
 396
 397 int serdev_device_set_tiocm(struct serdev_device *serdev, int set, int clear)
 398 {
 399         struct serdev_controller *ctrl = serdev->ctrl;
 400
 401         if (!ctrl || !ctrl->ops->set_tiocm)
 402                 return -ENOTSUPP;
 403
 404         return ctrl->ops->set_tiocm(ctrl, set, clear);
 405 }
 406 EXPORT_SYMBOL_GPL(serdev_device_set_tiocm);
 407
 408 static int serdev_drv_probe(struct device *dev)
 409 {
 410         const struct serdev_device_driver *sdrv = to_serdev_device_driver(dev->driver);
 411         int ret;
 412
 413         ret = dev_pm_domain_attach(dev, true);
 414         if (ret)
 415                 return ret;
 416
 417         ret = sdrv->probe(to_serdev_device(dev));
 418         if (ret)
 419                 dev_pm_domain_detach(dev, true);
 420
 421         return ret;
 422 }
 423
 424 static int serdev_drv_remove(struct device *dev)
 425 {
 426         const struct serdev_device_driver *sdrv = to_serdev_device_driver(dev->driver);
 427         if (sdrv->remove)
 428                 sdrv->remove(to_serdev_device(dev));
 429
 430         dev_pm_domain_detach(dev, true);
 431
 432         return 0;
 433 }
 434
 435 static struct bus_type serdev_bus_type = {
 436         .name           = "serial",
 437         .match          = serdev_device_match,
 438         .probe          = serdev_drv_probe,
 439         .remove         = serdev_drv_remove,
 440 };
 441
 442 /**
 443  * serdev_device_alloc() - Allocate a new serdev device
 444  * @ctrl:       associated controller
 445  *
 446  * Caller is responsible for either calling serdev_device_add() to add the
 447  * newly allocated controller, or calling serdev_device_put() to discard it.
 448  */
 449 struct serdev_device *serdev_device_alloc(struct serdev_controller *ctrl)
 450 {
 451         struct serdev_device *serdev;
 452
 453         serdev = kzalloc(sizeof(*serdev), GFP_KERNEL);
 454         if (!serdev)
 455                 return NULL;
 456
 457         serdev->ctrl = ctrl;
 458         device_initialize(&serdev->dev);
 459         serdev->dev.parent = &ctrl->dev;
 460         serdev->dev.bus = &serdev_bus_type;
 461         serdev->dev.type = &serdev_device_type;
 462         init_completion(&serdev->write_comp);
 463         mutex_init(&serdev->write_lock);
 464         return serdev;
 465 }
 466 EXPORT_SYMBOL_GPL(serdev_device_alloc);
 467
 468 /**
 469  * serdev_controller_alloc() - Allocate a new serdev controller
 470  * @parent:     parent device
 471  * @size:       size of private data
 472  *
 473  * Caller is responsible for either calling serdev_controller_add() to add the
 474  * newly allocated controller, or calling serdev_controller_put() to discard it.
 475  * The allocated private data region may be accessed via
 476  * serdev_controller_get_drvdata()
 477  */
 478 struct serdev_controller *serdev_controller_alloc(struct device *parent,
 479                                               size_t size)
 480 {
 481         struct serdev_controller *ctrl;
 482         int id;
 483
 484         if (WARN_ON(!parent))
 485                 return NULL;
 486
 487         ctrl = kzalloc(sizeof(*ctrl) + size, GFP_KERNEL);
 488         if (!ctrl)
 489                 return NULL;
 490
 491         id = ida_simple_get(&ctrl_ida, 0, 0, GFP_KERNEL);
 492         if (id < 0) {
 493                 dev_err(parent,
 494                         "unable to allocate serdev controller identifier.\n");
 495                 goto err_free;
 496         }
 497
 498         ctrl->nr = id;
 499
 500         device_initialize(&ctrl->dev);
 501         ctrl->dev.type = &serdev_ctrl_type;
 502         ctrl->dev.bus = &serdev_bus_type;
 503         ctrl->dev.parent = parent;
 504         ctrl->dev.of_node = parent->of_node;
 505         serdev_controller_set_drvdata(ctrl, &ctrl[1]);
 506
 507         dev_set_name(&ctrl->dev, "serial%d", id);
 508
 509         pm_runtime_no_callbacks(&ctrl->dev);
 510         pm_suspend_ignore_children(&ctrl->dev, true);
 511
 512         dev_dbg(&ctrl->dev, "allocated controller 0x%p id %d\n", ctrl, id);
 513         return ctrl;
 514
 515 err_free:
 516         kfree(ctrl);
 517
 518         return NULL;
 519 }
 520 EXPORT_SYMBOL_GPL(serdev_controller_alloc);
 521
 522 static int of_serdev_register_devices(struct serdev_controller *ctrl)
 523 {
 524         struct device_node *node;
 525         struct serdev_device *serdev = NULL;
 526         int err;
 527         bool found = false;
 528
 529         for_each_available_child_of_node(ctrl->dev.of_node, node) {
 530                 if (!of_get_property(node, "compatible", NULL))
 531                         continue;
 532
 533                 dev_dbg(&ctrl->dev, "adding child %pOF\n", node);
 534
 535                 serdev = serdev_device_alloc(ctrl);
 536                 if (!serdev)
 537                         continue;
 538
 539                 serdev->dev.of_node = node;
 540
 541                 err = serdev_device_add(serdev);
 542                 if (err) {
 543                         dev_err(&serdev->dev,
 544                                 "failure adding device. status %pe\n",
 545                                 ERR_PTR(err));
 546                         serdev_device_put(serdev);
 547                 } else
 548                         found = true;
 549         }
 550         if (!found)
 551                 return -ENODEV;
 552
 553         return 0;
 554 }
 555
 556 #ifdef CONFIG_ACPI
 557
 558 #define SERDEV_ACPI_MAX_SCAN_DEPTH 32
 559
 560 struct acpi_serdev_lookup {
 561         acpi_handle device_handle;
 562         acpi_handle controller_handle;
 563         int n;
 564         int index;
 565 };
 566
 567 static int acpi_serdev_parse_resource(struct acpi_resource *ares, void *data)
 568 {
 569         struct acpi_serdev_lookup *lookup = data;
 570         struct acpi_resource_uart_serialbus *sb;
 571         acpi_status status;
 572
 573         if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
 574                 return 1;
 575
 576         if (ares->data.common_serial_bus.type != ACPI_RESOURCE_SERIAL_TYPE_UART)
 577                 return 1;
 578
 579         if (lookup->index != -1 && lookup->n++ != lookup->index)
 580                 return 1;
 581
 582         sb = &ares->data.uart_serial_bus;
 583
 584         status = acpi_get_handle(lookup->device_handle,
 585                                  sb->resource_source.string_ptr,
 586                                  &lookup->controller_handle);
 587         if (ACPI_FAILURE(status))
 588                 return 1;
 589
 590         /*
 591          * NOTE: Ideally, we would also want to retreive other properties here,
 592          * once setting them before opening the device is supported by serdev.
 593          */
 594
 595         return 1;
 596 }
 597
 598 static int acpi_serdev_do_lookup(struct acpi_device *adev,
 599                                  struct acpi_serdev_lookup *lookup)
 600 {
 601         struct list_head resource_list;
 602         int ret;
 603
 604         lookup->device_handle = acpi_device_handle(adev);
 605         lookup->controller_handle = NULL;
 606         lookup->n = 0;
 607
 608         INIT_LIST_HEAD(&resource_list);
 609         ret = acpi_dev_get_resources(adev, &resource_list,
 610                                      acpi_serdev_parse_resource, lookup);
 611         acpi_dev_free_resource_list(&resource_list);
 612
 613         if (ret < 0)
 614                 return -EINVAL;
 615
 616         return 0;
 617 }
 618
 619 static int acpi_serdev_check_resources(struct serdev_controller *ctrl,
 620                                        struct acpi_device *adev)
 621 {
 622         struct acpi_serdev_lookup lookup;
 623         int ret;
 624
 625         if (acpi_bus_get_status(adev) || !adev->status.present)
 626                 return -EINVAL;
 627
 628         /* Look for UARTSerialBusV2 resource */
 629         lookup.index = -1;      // we only care for the last device
 630
 631         ret = acpi_serdev_do_lookup(adev, &lookup);
 632         if (ret)
 633                 return ret;
 634
 635         /*
 636          * Apple machines provide an empty resource template, so on those
 637          * machines just look for immediate children with a "baud" property
 638          * (from the _DSM method) instead.
 639          */
 640         if (!lookup.controller_handle && x86_apple_machine &&
 641             !acpi_dev_get_property(adev, "baud", ACPI_TYPE_BUFFER, NULL))
 642                 acpi_get_parent(adev->handle, &lookup.controller_handle);
 643
 644         /* Make sure controller and ResourceSource handle match */
 645         if (ACPI_HANDLE(ctrl->dev.parent) != lookup.controller_handle)
 646                 return -ENODEV;
 647
 648         return 0;
 649 }
 650
 651 static acpi_status acpi_serdev_register_device(struct serdev_controller *ctrl,
 652                                                struct acpi_device *adev)
 653 {
 654         struct serdev_device *serdev;
 655         int err;
 656
 657         serdev = serdev_device_alloc(ctrl);
 658         if (!serdev) {
 659                 dev_err(&ctrl->dev, "failed to allocate serdev device for %s\n",
 660                         dev_name(&adev->dev));
 661                 return AE_NO_MEMORY;
 662         }
 663
 664         ACPI_COMPANION_SET(&serdev->dev, adev);
 665         acpi_device_set_enumerated(adev);
 666
 667         err = serdev_device_add(serdev);
 668         if (err) {
 669                 dev_err(&serdev->dev,
 670                         "failure adding ACPI serdev device. status %pe\n",
 671                         ERR_PTR(err));
 672                 serdev_device_put(serdev);
 673         }
 674
 675         return AE_OK;
 676 }
 677
 678 static const struct acpi_device_id serdev_acpi_devices_blacklist[] = {
 679         { "INT3511", 0 },
 680         { "INT3512", 0 },
 681         { },
 682 };
 683
 684 static acpi_status acpi_serdev_add_device(acpi_handle handle, u32 level,
 685                                           void *data, void **return_value)
 686 {
 687         struct serdev_controller *ctrl = data;
 688         struct acpi_device *adev;
 689
 690         if (acpi_bus_get_device(handle, &adev))
 691                 return AE_OK;
 692
 693         if (acpi_device_enumerated(adev))
 694                 return AE_OK;
 695
 696         /* Skip if black listed */
 697         if (!acpi_match_device_ids(adev, serdev_acpi_devices_blacklist))
 698                 return AE_OK;
 699
 700         if (acpi_serdev_check_resources(ctrl, adev))
 701                 return AE_OK;
 702
 703         return acpi_serdev_register_device(ctrl, adev);
 704 }
 705
 706
 707 static int acpi_serdev_register_devices(struct serdev_controller *ctrl)
 708 {
 709         acpi_status status;
 710
 711         if (!has_acpi_companion(ctrl->dev.parent))
 712                 return -ENODEV;
 713
 714         status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 715                                      SERDEV_ACPI_MAX_SCAN_DEPTH,
 716                                      acpi_serdev_add_device, NULL, ctrl, NULL);
 717         if (ACPI_FAILURE(status))
 718                 dev_warn(&ctrl->dev, "failed to enumerate serdev slaves\n");
 719
 720         if (!ctrl->serdev)
 721                 return -ENODEV;
 722
 723         return 0;
 724 }
 725 #else
 726 static inline int acpi_serdev_register_devices(struct serdev_controller *ctrl)
 727 {
 728         return -ENODEV;
 729 }
 730 #endif /* CONFIG_ACPI */
 731
 732 /**
 733  * serdev_controller_add() - Add an serdev controller
 734  * @ctrl:       controller to be registered.
 735  *
 736  * Register a controller previously allocated via serdev_controller_alloc() with
 737  * the serdev core.
 738  */
 739 int serdev_controller_add(struct serdev_controller *ctrl)
 740 {
 741         int ret_of, ret_acpi, ret;
 742
 743         /* Can't register until after driver model init */
 744         if (WARN_ON(!is_registered))
 745                 return -EAGAIN;
 746
 747         ret = device_add(&ctrl->dev);
 748         if (ret)
 749                 return ret;
 750
 751         pm_runtime_enable(&ctrl->dev);
 752
 753         ret_of = of_serdev_register_devices(ctrl);
 754         ret_acpi = acpi_serdev_register_devices(ctrl);
 755         if (ret_of && ret_acpi) {
 756                 dev_dbg(&ctrl->dev, "no devices registered: of:%pe acpi:%pe\n",
 757                         ERR_PTR(ret_of), ERR_PTR(ret_acpi));
 758                 ret = -ENODEV;
 759                 goto err_rpm_disable;
 760         }
 761
 762         dev_dbg(&ctrl->dev, "serdev%d registered: dev:%p\n",
 763                 ctrl->nr, &ctrl->dev);
 764         return 0;
 765
 766 err_rpm_disable:
 767         pm_runtime_disable(&ctrl->dev);
 768         device_del(&ctrl->dev);
 769         return ret;
 770 };
 771 EXPORT_SYMBOL_GPL(serdev_controller_add);
 772
 773 /* Remove a device associated with a controller */
 774 static int serdev_remove_device(struct device *dev, void *data)
 775 {
 776         struct serdev_device *serdev = to_serdev_device(dev);
 777         if (dev->type == &serdev_device_type)
 778                 serdev_device_remove(serdev);
 779         return 0;
 780 }
 781
 782 /**
 783  * serdev_controller_remove(): remove an serdev controller
 784  * @ctrl:       controller to remove
 785  *
 786  * Remove a serdev controller.  Caller is responsible for calling
 787  * serdev_controller_put() to discard the allocated controller.
 788  */
 789 void serdev_controller_remove(struct serdev_controller *ctrl)
 790 {
 791         int dummy;
 792
 793         if (!ctrl)
 794                 return;
 795
 796         dummy = device_for_each_child(&ctrl->dev, NULL,
 797                                       serdev_remove_device);
 798         pm_runtime_disable(&ctrl->dev);
 799         device_del(&ctrl->dev);
 800 }
 801 EXPORT_SYMBOL_GPL(serdev_controller_remove);
 802
 803 /**
 804  * serdev_driver_register() - Register client driver with serdev core
 805  * @sdrv:       client driver to be associated with client-device.
 806  *
 807  * This API will register the client driver with the serdev framework.
 808  * It is typically called from the driver's module-init function.
 809  */
 810 int __serdev_device_driver_register(struct serdev_device_driver *sdrv, struct module *owner)
 811 {
 812         sdrv->driver.bus = &serdev_bus_type;
 813         sdrv->driver.owner = owner;
 814
 815         /* force drivers to async probe so I/O is possible in probe */
 816         sdrv->driver.probe_type = PROBE_PREFER_ASYNCHRONOUS;
 817
 818         return driver_register(&sdrv->driver);
 819 }
 820 EXPORT_SYMBOL_GPL(__serdev_device_driver_register);
 821
 822 static void __exit serdev_exit(void)
 823 {
 824         bus_unregister(&serdev_bus_type);
 825         ida_destroy(&ctrl_ida);
 826 }
 827 module_exit(serdev_exit);
 828
 829 static int __init serdev_init(void)
 830 {
 831         int ret;
 832
 833         ret = bus_register(&serdev_bus_type);
 834         if (ret)
 835                 return ret;
 836
 837         is_registered = true;
 838         return 0;
 839 }
 840 /* Must be before serial drivers register */
 841 postcore_initcall(serdev_init);
 842
 843 MODULE_AUTHOR("Rob Herring <robh@kernel.org>");
 844 MODULE_LICENSE("GPL v2");
 845 MODULE_DESCRIPTION("Serial attached device bus");