drivers/usb/typec/pd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * USB Power Delivery sysfs entries
   4  *
   5  * Copyright (C) 2022, Intel Corporation
   6  * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
   7  */
   8
   9 #include <linux/slab.h>
  10 #include <linux/usb/pd.h>
  11
  12 #include "pd.h"
  13
  14 static DEFINE_IDA(pd_ida);
  15
  16 static struct class pd_class = {
  17         .name = "usb_power_delivery",
  18 };
  19
  20 #define to_pdo(o) container_of(o, struct pdo, dev)
  21
  22 struct pdo {
  23         struct device dev;
  24         int object_position;
  25         u32 pdo;
  26 };
  27
  28 static void pdo_release(struct device *dev)
  29 {
  30         kfree(to_pdo(dev));
  31 }
  32
  33 /* -------------------------------------------------------------------------- */
  34 /* Fixed Supply */
  35
  36 static ssize_t
  37 dual_role_power_show(struct device *dev, struct device_attribute *attr, char *buf)
  38 {
  39         return sysfs_emit(buf, "%u\n", !!(to_pdo(dev)->pdo & PDO_FIXED_DUAL_ROLE));
  40 }
  41 static DEVICE_ATTR_RO(dual_role_power);
  42
  43 static ssize_t
  44 usb_suspend_supported_show(struct device *dev, struct device_attribute *attr, char *buf)
  45 {
  46         return sysfs_emit(buf, "%u\n", !!(to_pdo(dev)->pdo & PDO_FIXED_SUSPEND));
  47 }
  48 static DEVICE_ATTR_RO(usb_suspend_supported);
  49
  50 static ssize_t
  51 higher_capability_show(struct device *dev, struct device_attribute *attr, char *buf)
  52 {
  53         return sysfs_emit(buf, "%u\n", !!(to_pdo(dev)->pdo & PDO_FIXED_HIGHER_CAP));
  54 }
  55 static DEVICE_ATTR_RO(higher_capability);
  56
  57 static ssize_t
  58 unconstrained_power_show(struct device *dev, struct device_attribute *attr, char *buf)
  59 {
  60         return sysfs_emit(buf, "%u\n", !!(to_pdo(dev)->pdo & PDO_FIXED_EXTPOWER));
  61 }
  62 static DEVICE_ATTR_RO(unconstrained_power);
  63
  64 static ssize_t
  65 usb_communication_capable_show(struct device *dev, struct device_attribute *attr, char *buf)
  66 {
  67         return sysfs_emit(buf, "%u\n", !!(to_pdo(dev)->pdo & PDO_FIXED_USB_COMM));
  68 }
  69 static DEVICE_ATTR_RO(usb_communication_capable);
  70
  71 static ssize_t
  72 dual_role_data_show(struct device *dev, struct device_attribute *attr, char *buf)
  73 {
  74         return sysfs_emit(buf, "%u\n", !!(to_pdo(dev)->pdo & PDO_FIXED_DATA_SWAP));
  75 }
  76 static DEVICE_ATTR_RO(dual_role_data);
  77
  78 static ssize_t
  79 unchunked_extended_messages_supported_show(struct device *dev,
  80                                            struct device_attribute *attr, char *buf)
  81 {
  82         return sysfs_emit(buf, "%u\n", !!(to_pdo(dev)->pdo & PDO_FIXED_UNCHUNK_EXT));
  83 }
  84 static DEVICE_ATTR_RO(unchunked_extended_messages_supported);
  85
  86 /*
  87  * REVISIT: Peak Current requires access also to the RDO.
  88 static ssize_t
  89 peak_current_show(struct device *dev, struct device_attribute *attr, char *buf)
  90 {
  91         ...
  92 }
  93 */
  94
  95 static ssize_t
  96 fast_role_swap_current_show(struct device *dev, struct device_attribute *attr, char *buf)
  97 {
  98         return sysfs_emit(buf, "%u\n", to_pdo(dev)->pdo >> PDO_FIXED_FRS_CURR_SHIFT) & 3;
  99 }
 100 static DEVICE_ATTR_RO(fast_role_swap_current);
 101
 102 static ssize_t voltage_show(struct device *dev, struct device_attribute *attr, char *buf)
 103 {
 104         return sysfs_emit(buf, "%umV\n", pdo_fixed_voltage(to_pdo(dev)->pdo));
 105 }
 106 static DEVICE_ATTR_RO(voltage);
 107
 108 /* Shared with Variable supplies, both source and sink */
 109 static ssize_t current_show(struct device *dev, struct device_attribute *attr, char *buf)
 110 {
 111         return sysfs_emit(buf, "%umA\n", pdo_max_current(to_pdo(dev)->pdo));
 112 }
 113
 114 /* Shared with Variable type supplies */
 115 static struct device_attribute maximum_current_attr = {
 116         .attr = {
 117                 .name = "maximum_current",
 118                 .mode = 0444,
 119         },
 120         .show = current_show,
 121 };
 122
 123 static struct device_attribute operational_current_attr = {
 124         .attr = {
 125                 .name = "operational_current",
 126                 .mode = 0444,
 127         },
 128         .show = current_show,
 129 };
 130
 131 static struct attribute *source_fixed_supply_attrs[] = {
 132         &dev_attr_dual_role_power.attr,
 133         &dev_attr_usb_suspend_supported.attr,
 134         &dev_attr_unconstrained_power.attr,
 135         &dev_attr_usb_communication_capable.attr,
 136         &dev_attr_dual_role_data.attr,
 137         &dev_attr_unchunked_extended_messages_supported.attr,
 138         /*&dev_attr_peak_current.attr,*/
 139         &dev_attr_voltage.attr,
 140         &maximum_current_attr.attr,
 141         NULL
 142 };
 143
 144 static umode_t fixed_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n)
 145 {
 146         if (to_pdo(kobj_to_dev(kobj))->object_position &&
 147             /*attr != &dev_attr_peak_current.attr &&*/
 148             attr != &dev_attr_voltage.attr &&
 149             attr != &maximum_current_attr.attr &&
 150             attr != &operational_current_attr.attr)
 151                 return 0;
 152
 153         return attr->mode;
 154 }
 155
 156 static const struct attribute_group source_fixed_supply_group = {
 157         .is_visible = fixed_attr_is_visible,
 158         .attrs = source_fixed_supply_attrs,
 159 };
 160 __ATTRIBUTE_GROUPS(source_fixed_supply);
 161
 162 static struct device_type source_fixed_supply_type = {
 163         .name = "pdo",
 164         .release = pdo_release,
 165         .groups = source_fixed_supply_groups,
 166 };
 167
 168 static struct attribute *sink_fixed_supply_attrs[] = {
 169         &dev_attr_dual_role_power.attr,
 170         &dev_attr_higher_capability.attr,
 171         &dev_attr_unconstrained_power.attr,
 172         &dev_attr_usb_communication_capable.attr,
 173         &dev_attr_dual_role_data.attr,
 174         &dev_attr_unchunked_extended_messages_supported.attr,
 175         &dev_attr_fast_role_swap_current.attr,
 176         &dev_attr_voltage.attr,
 177         &operational_current_attr.attr,
 178         NULL
 179 };
 180
 181 static const struct attribute_group sink_fixed_supply_group = {
 182         .is_visible = fixed_attr_is_visible,
 183         .attrs = sink_fixed_supply_attrs,
 184 };
 185 __ATTRIBUTE_GROUPS(sink_fixed_supply);
 186
 187 static struct device_type sink_fixed_supply_type = {
 188         .name = "pdo",
 189         .release = pdo_release,
 190         .groups = sink_fixed_supply_groups,
 191 };
 192
 193 /* -------------------------------------------------------------------------- */
 194 /* Variable Supply */
 195
 196 static ssize_t
 197 maximum_voltage_show(struct device *dev, struct device_attribute *attr, char *buf)
 198 {
 199         return sysfs_emit(buf, "%umV\n", pdo_max_voltage(to_pdo(dev)->pdo));
 200 }
 201 static DEVICE_ATTR_RO(maximum_voltage);
 202
 203 static ssize_t
 204 minimum_voltage_show(struct device *dev, struct device_attribute *attr, char *buf)
 205 {
 206         return sysfs_emit(buf, "%umV\n", pdo_min_voltage(to_pdo(dev)->pdo));
 207 }
 208 static DEVICE_ATTR_RO(minimum_voltage);
 209
 210 static struct attribute *source_variable_supply_attrs[] = {
 211         &dev_attr_maximum_voltage.attr,
 212         &dev_attr_minimum_voltage.attr,
 213         &maximum_current_attr.attr,
 214         NULL
 215 };
 216 ATTRIBUTE_GROUPS(source_variable_supply);
 217
 218 static struct device_type source_variable_supply_type = {
 219         .name = "pdo",
 220         .release = pdo_release,
 221         .groups = source_variable_supply_groups,
 222 };
 223
 224 static struct attribute *sink_variable_supply_attrs[] = {
 225         &dev_attr_maximum_voltage.attr,
 226         &dev_attr_minimum_voltage.attr,
 227         &operational_current_attr.attr,
 228         NULL
 229 };
 230 ATTRIBUTE_GROUPS(sink_variable_supply);
 231
 232 static struct device_type sink_variable_supply_type = {
 233         .name = "pdo",
 234         .release = pdo_release,
 235         .groups = sink_variable_supply_groups,
 236 };
 237
 238 /* -------------------------------------------------------------------------- */
 239 /* Battery */
 240
 241 static ssize_t
 242 maximum_power_show(struct device *dev, struct device_attribute *attr, char *buf)
 243 {
 244         return sysfs_emit(buf, "%umW\n", pdo_max_power(to_pdo(dev)->pdo));
 245 }
 246 static DEVICE_ATTR_RO(maximum_power);
 247
 248 static ssize_t
 249 operational_power_show(struct device *dev, struct device_attribute *attr, char *buf)
 250 {
 251         return sysfs_emit(buf, "%umW\n", pdo_max_power(to_pdo(dev)->pdo));
 252 }
 253 static DEVICE_ATTR_RO(operational_power);
 254
 255 static struct attribute *source_battery_attrs[] = {
 256         &dev_attr_maximum_voltage.attr,
 257         &dev_attr_minimum_voltage.attr,
 258         &dev_attr_maximum_power.attr,
 259         NULL
 260 };
 261 ATTRIBUTE_GROUPS(source_battery);
 262
 263 static struct device_type source_battery_type = {
 264         .name = "pdo",
 265         .release = pdo_release,
 266         .groups = source_battery_groups,
 267 };
 268
 269 static struct attribute *sink_battery_attrs[] = {
 270         &dev_attr_maximum_voltage.attr,
 271         &dev_attr_minimum_voltage.attr,
 272         &dev_attr_operational_power.attr,
 273         NULL
 274 };
 275 ATTRIBUTE_GROUPS(sink_battery);
 276
 277 static struct device_type sink_battery_type = {
 278         .name = "pdo",
 279         .release = pdo_release,
 280         .groups = sink_battery_groups,
 281 };
 282
 283 /* -------------------------------------------------------------------------- */
 284 /* Standard Power Range (SPR) Programmable Power Supply (PPS) */
 285
 286 static ssize_t
 287 pps_power_limited_show(struct device *dev, struct device_attribute *attr, char *buf)
 288 {
 289         return sysfs_emit(buf, "%u\n", !!(to_pdo(dev)->pdo & BIT(27)));
 290 }
 291 static DEVICE_ATTR_RO(pps_power_limited);
 292
 293 static ssize_t
 294 pps_max_voltage_show(struct device *dev, struct device_attribute *attr, char *buf)
 295 {
 296         return sysfs_emit(buf, "%umV\n", pdo_pps_apdo_max_voltage(to_pdo(dev)->pdo));
 297 }
 298
 299 static ssize_t
 300 pps_min_voltage_show(struct device *dev, struct device_attribute *attr, char *buf)
 301 {
 302         return sysfs_emit(buf, "%umV\n", pdo_pps_apdo_min_voltage(to_pdo(dev)->pdo));
 303 }
 304
 305 static ssize_t
 306 pps_max_current_show(struct device *dev, struct device_attribute *attr, char *buf)
 307 {
 308         return sysfs_emit(buf, "%umA\n", pdo_pps_apdo_max_current(to_pdo(dev)->pdo));
 309 }
 310
 311 static struct device_attribute pps_max_voltage_attr = {
 312         .attr = {
 313                 .name = "maximum_voltage",
 314                 .mode = 0444,
 315         },
 316         .show = pps_max_voltage_show,
 317 };
 318
 319 static struct device_attribute pps_min_voltage_attr = {
 320         .attr = {
 321                 .name = "minimum_voltage",
 322                 .mode = 0444,
 323         },
 324         .show = pps_min_voltage_show,
 325 };
 326
 327 static struct device_attribute pps_max_current_attr = {
 328         .attr = {
 329                 .name = "maximum_current",
 330                 .mode = 0444,
 331         },
 332         .show = pps_max_current_show,
 333 };
 334
 335 static struct attribute *source_pps_attrs[] = {
 336         &dev_attr_pps_power_limited.attr,
 337         &pps_max_voltage_attr.attr,
 338         &pps_min_voltage_attr.attr,
 339         &pps_max_current_attr.attr,
 340         NULL
 341 };
 342 ATTRIBUTE_GROUPS(source_pps);
 343
 344 static struct device_type source_pps_type = {
 345         .name = "pdo",
 346         .release = pdo_release,
 347         .groups = source_pps_groups,
 348 };
 349
 350 static struct attribute *sink_pps_attrs[] = {
 351         &pps_max_voltage_attr.attr,
 352         &pps_min_voltage_attr.attr,
 353         &pps_max_current_attr.attr,
 354         NULL
 355 };
 356 ATTRIBUTE_GROUPS(sink_pps);
 357
 358 static struct device_type sink_pps_type = {
 359         .name = "pdo",
 360         .release = pdo_release,
 361         .groups = sink_pps_groups,
 362 };
 363
 364 /* -------------------------------------------------------------------------- */
 365
 366 static const char * const supply_name[] = {
 367         [PDO_TYPE_FIXED] = "fixed_supply",
 368         [PDO_TYPE_BATT]  = "battery",
 369         [PDO_TYPE_VAR]   = "variable_supply",
 370 };
 371
 372 static const char * const apdo_supply_name[] = {
 373         [APDO_TYPE_PPS]  = "programmable_supply",
 374 };
 375
 376 static struct device_type *source_type[] = {
 377         [PDO_TYPE_FIXED] = &source_fixed_supply_type,
 378         [PDO_TYPE_BATT]  = &source_battery_type,
 379         [PDO_TYPE_VAR]   = &source_variable_supply_type,
 380 };
 381
 382 static struct device_type *source_apdo_type[] = {
 383         [APDO_TYPE_PPS]  = &source_pps_type,
 384 };
 385
 386 static struct device_type *sink_type[] = {
 387         [PDO_TYPE_FIXED] = &sink_fixed_supply_type,
 388         [PDO_TYPE_BATT]  = &sink_battery_type,
 389         [PDO_TYPE_VAR]   = &sink_variable_supply_type,
 390 };
 391
 392 static struct device_type *sink_apdo_type[] = {
 393         [APDO_TYPE_PPS]  = &sink_pps_type,
 394 };
 395
 396 /* REVISIT: Export when EPR_*_Capabilities need to be supported. */
 397 static int add_pdo(struct usb_power_delivery_capabilities *cap, u32 pdo, int position)
 398 {
 399         struct device_type *type;
 400         const char *name;
 401         struct pdo *p;
 402         int ret;
 403
 404         p = kzalloc(sizeof(*p), GFP_KERNEL);
 405         if (!p)
 406                 return -ENOMEM;
 407
 408         p->pdo = pdo;
 409         p->object_position = position;
 410
 411         if (pdo_type(pdo) == PDO_TYPE_APDO) {
 412                 /* FIXME: Only PPS supported for now! Skipping others. */
 413                 if (pdo_apdo_type(pdo) > APDO_TYPE_PPS) {
 414                         dev_warn(&cap->dev, "Unknown APDO type. PDO 0x%08x\n", pdo);
 415                         kfree(p);
 416                         return 0;
 417                 }
 418
 419                 if (is_source(cap->role))
 420                         type = source_apdo_type[pdo_apdo_type(pdo)];
 421                 else
 422                         type = sink_apdo_type[pdo_apdo_type(pdo)];
 423
 424                 name = apdo_supply_name[pdo_apdo_type(pdo)];
 425         } else {
 426                 if (is_source(cap->role))
 427                         type = source_type[pdo_type(pdo)];
 428                 else
 429                         type = sink_type[pdo_type(pdo)];
 430
 431                 name = supply_name[pdo_type(pdo)];
 432         }
 433
 434         p->dev.parent = &cap->dev;
 435         p->dev.type = type;
 436         dev_set_name(&p->dev, "%u:%s", position + 1, name);
 437
 438         ret = device_register(&p->dev);
 439         if (ret) {
 440                 put_device(&p->dev);
 441                 return ret;
 442         }
 443
 444         return 0;
 445 }
 446
 447 static int remove_pdo(struct device *dev, void *data)
 448 {
 449         device_unregister(dev);
 450         return 0;
 451 }
 452
 453 /* -------------------------------------------------------------------------- */
 454
 455 static const char * const cap_name[] = {
 456         [TYPEC_SINK]    = "sink-capabilities",
 457         [TYPEC_SOURCE]  = "source-capabilities",
 458 };
 459
 460 static void pd_capabilities_release(struct device *dev)
 461 {
 462         kfree(to_usb_power_delivery_capabilities(dev));
 463 }
 464
 465 static struct device_type pd_capabilities_type = {
 466         .name = "capabilities",
 467         .release = pd_capabilities_release,
 468 };
 469
 470 /**
 471  * usb_power_delivery_register_capabilities - Register a set of capabilities.
 472  * @pd: The USB PD instance that the capabilities belong to.
 473  * @desc: Description of the Capablities Message.
 474  *
 475  * This function registers a Capabilities Message described in @desc. The
 476  * capabilities will have their own sub-directory under @pd in sysfs.
 477  *
 478  * The function returns pointer to struct usb_power_delivery_capabilities, or
 479  * ERR_PRT(errno).
 480  */
 481 struct usb_power_delivery_capabilities *
 482 usb_power_delivery_register_capabilities(struct usb_power_delivery *pd,
 483                                          struct usb_power_delivery_capabilities_desc *desc)
 484 {
 485         struct usb_power_delivery_capabilities *cap;
 486         int ret;
 487         int i;
 488
 489         cap = kzalloc(sizeof(*cap), GFP_KERNEL);
 490         if (!cap)
 491                 return ERR_PTR(-ENOMEM);
 492
 493         cap->pd = pd;
 494         cap->role = desc->role;
 495
 496         cap->dev.parent = &pd->dev;
 497         cap->dev.type = &pd_capabilities_type;
 498         dev_set_name(&cap->dev, "%s", cap_name[cap->role]);
 499
 500         ret = device_register(&cap->dev);
 501         if (ret) {
 502                 put_device(&cap->dev);
 503                 return ERR_PTR(ret);
 504         }
 505
 506         for (i = 0; i < PDO_MAX_OBJECTS && desc->pdo[i]; i++) {
 507                 ret = add_pdo(cap, desc->pdo[i], i);
 508                 if (ret) {
 509                         usb_power_delivery_unregister_capabilities(cap);
 510                         return ERR_PTR(ret);
 511                 }
 512         }
 513
 514         return cap;
 515 }
 516 EXPORT_SYMBOL_GPL(usb_power_delivery_register_capabilities);
 517
 518 /**
 519  * usb_power_delivery_unregister_capabilities - Unregister a set of capabilities
 520  * @cap: The capabilities
 521  */
 522 void usb_power_delivery_unregister_capabilities(struct usb_power_delivery_capabilities *cap)
 523 {
 524         if (!cap)
 525                 return;
 526
 527         device_for_each_child(&cap->dev, NULL, remove_pdo);
 528         device_unregister(&cap->dev);
 529 }
 530 EXPORT_SYMBOL_GPL(usb_power_delivery_unregister_capabilities);
 531
 532 /* -------------------------------------------------------------------------- */
 533
 534 static ssize_t revision_show(struct device *dev, struct device_attribute *attr, char *buf)
 535 {
 536         struct usb_power_delivery *pd = to_usb_power_delivery(dev);
 537
 538         return sysfs_emit(buf, "%u.%u\n", (pd->revision >> 8) & 0xff, (pd->revision >> 4) & 0xf);
 539 }
 540 static DEVICE_ATTR_RO(revision);
 541
 542 static ssize_t version_show(struct device *dev, struct device_attribute *attr, char *buf)
 543 {
 544         struct usb_power_delivery *pd = to_usb_power_delivery(dev);
 545
 546         return sysfs_emit(buf, "%u.%u\n", (pd->version >> 8) & 0xff, (pd->version >> 4) & 0xf);
 547 }
 548 static DEVICE_ATTR_RO(version);
 549
 550 static struct attribute *pd_attrs[] = {
 551         &dev_attr_revision.attr,
 552         &dev_attr_version.attr,
 553         NULL
 554 };
 555
 556 static umode_t pd_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n)
 557 {
 558         struct usb_power_delivery *pd = to_usb_power_delivery(kobj_to_dev(kobj));
 559
 560         if (attr == &dev_attr_version.attr && !pd->version)
 561                 return 0;
 562
 563         return attr->mode;
 564 }
 565
 566 static const struct attribute_group pd_group = {
 567         .is_visible = pd_attr_is_visible,
 568         .attrs = pd_attrs,
 569 };
 570 __ATTRIBUTE_GROUPS(pd);
 571
 572 static void pd_release(struct device *dev)
 573 {
 574         struct usb_power_delivery *pd = to_usb_power_delivery(dev);
 575
 576         ida_simple_remove(&pd_ida, pd->id);
 577         kfree(pd);
 578 }
 579
 580 static struct device_type pd_type = {
 581         .name = "usb_power_delivery",
 582         .release = pd_release,
 583         .groups = pd_groups,
 584 };
 585
 586 struct usb_power_delivery *usb_power_delivery_find(const char *name)
 587 {
 588         struct device *dev;
 589
 590         dev = class_find_device_by_name(&pd_class, name);
 591
 592         return dev ? to_usb_power_delivery(dev) : NULL;
 593 }
 594
 595 /**
 596  * usb_power_delivery_register - Register USB Power Delivery Support.
 597  * @parent: Parent device.
 598  * @desc: Description of the USB PD contract.
 599  *
 600  * This routine can be used to register USB Power Delivery capabilities that a
 601  * device or devices can support. These capabilities represent all the
 602  * capabilities that can be negotiated with a partner, so not only the Power
 603  * Capabilities that are negotiated using the USB PD Capabilities Message.
 604  *
 605  * The USB Power Delivery Support object that this routine generates can be used
 606  * as the parent object for all the actual USB Power Delivery Messages and
 607  * objects that can be negotiated with the partner.
 608  *
 609  * Returns handle to struct usb_power_delivery or ERR_PTR.
 610  */
 611 struct usb_power_delivery *
 612 usb_power_delivery_register(struct device *parent, struct usb_power_delivery_desc *desc)
 613 {
 614         struct usb_power_delivery *pd;
 615         int ret;
 616
 617         pd = kzalloc(sizeof(*pd), GFP_KERNEL);
 618         if (!pd)
 619                 return ERR_PTR(-ENOMEM);
 620
 621         ret = ida_simple_get(&pd_ida, 0, 0, GFP_KERNEL);
 622         if (ret < 0) {
 623                 kfree(pd);
 624                 return ERR_PTR(ret);
 625         }
 626
 627         pd->id = ret;
 628         pd->revision = desc->revision;
 629         pd->version = desc->version;
 630
 631         pd->dev.parent = parent;
 632         pd->dev.type = &pd_type;
 633         pd->dev.class = &pd_class;
 634         dev_set_name(&pd->dev, "pd%d", pd->id);
 635
 636         ret = device_register(&pd->dev);
 637         if (ret) {
 638                 put_device(&pd->dev);
 639                 return ERR_PTR(ret);
 640         }
 641
 642         return pd;
 643 }
 644 EXPORT_SYMBOL_GPL(usb_power_delivery_register);
 645
 646 /**
 647  * usb_power_delivery_unregister - Unregister USB Power Delivery Support.
 648  * @pd: The USB PD contract.
 649  */
 650 void usb_power_delivery_unregister(struct usb_power_delivery *pd)
 651 {
 652         if (IS_ERR_OR_NULL(pd))
 653                 return;
 654
 655         device_unregister(&pd->dev);
 656 }
 657 EXPORT_SYMBOL_GPL(usb_power_delivery_unregister);
 658
 659 /**
 660  * usb_power_delivery_link_device - Link device to its USB PD object.
 661  * @pd: The USB PD instance.
 662  * @dev: The device.
 663  *
 664  * This function can be used to create a symlink named "usb_power_delivery" for
 665  * @dev that points to @pd.
 666  */
 667 int usb_power_delivery_link_device(struct usb_power_delivery *pd, struct device *dev)
 668 {
 669         int ret;
 670
 671         if (IS_ERR_OR_NULL(pd) || !dev)
 672                 return 0;
 673
 674         ret = sysfs_create_link(&dev->kobj, &pd->dev.kobj, "usb_power_delivery");
 675         if (ret)
 676                 return ret;
 677
 678         get_device(&pd->dev);
 679         get_device(dev);
 680
 681         return 0;
 682 }
 683 EXPORT_SYMBOL_GPL(usb_power_delivery_link_device);
 684
 685 /**
 686  * usb_power_delivery_unlink_device - Unlink device from its USB PD object.
 687  * @pd: The USB PD instance.
 688  * @dev: The device.
 689  *
 690  * Remove the symlink that was previously created with pd_link_device().
 691  */
 692 void usb_power_delivery_unlink_device(struct usb_power_delivery *pd, struct device *dev)
 693 {
 694         if (IS_ERR_OR_NULL(pd) || !dev)
 695                 return;
 696
 697         sysfs_remove_link(&dev->kobj, "usb_power_delivery");
 698         put_device(&pd->dev);
 699         put_device(dev);
 700 }
 701 EXPORT_SYMBOL_GPL(usb_power_delivery_unlink_device);
 702
 703 /* -------------------------------------------------------------------------- */
 704
 705 int __init usb_power_delivery_init(void)
 706 {
 707         return class_register(&pd_class);
 708 }
 709
 710 void __exit usb_power_delivery_exit(void)
 711 {
 712         ida_destroy(&pd_ida);
 713         class_unregister(&pd_class);
 714 }