include/linux/thunderbolt.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Thunderbolt service API
   4  *
   5  * Copyright (C) 2014 Andreas Noever <andreas.noever@gmail.com>
   6  * Copyright (C) 2017, Intel Corporation
   7  * Authors: Michael Jamet <michael.jamet@intel.com>
   8  *          Mika Westerberg <mika.westerberg@linux.intel.com>
   9  */
  10
  11 #ifndef THUNDERBOLT_H_
  12 #define THUNDERBOLT_H_
  13
  14 #include <linux/device.h>
  15 #include <linux/idr.h>
  16 #include <linux/list.h>
  17 #include <linux/mutex.h>
  18 #include <linux/mod_devicetable.h>
  19 #include <linux/pci.h>
  20 #include <linux/uuid.h>
  21 #include <linux/workqueue.h>
  22
  23 enum tb_cfg_pkg_type {
  24         TB_CFG_PKG_READ = 1,
  25         TB_CFG_PKG_WRITE = 2,
  26         TB_CFG_PKG_ERROR = 3,
  27         TB_CFG_PKG_NOTIFY_ACK = 4,
  28         TB_CFG_PKG_EVENT = 5,
  29         TB_CFG_PKG_XDOMAIN_REQ = 6,
  30         TB_CFG_PKG_XDOMAIN_RESP = 7,
  31         TB_CFG_PKG_OVERRIDE = 8,
  32         TB_CFG_PKG_RESET = 9,
  33         TB_CFG_PKG_ICM_EVENT = 10,
  34         TB_CFG_PKG_ICM_CMD = 11,
  35         TB_CFG_PKG_ICM_RESP = 12,
  36         TB_CFG_PKG_PREPARE_TO_SLEEP = 13,
  37 };
  38
  39 /**
  40  * enum tb_security_level - Thunderbolt security level
  41  * @TB_SECURITY_NONE: No security, legacy mode
  42  * @TB_SECURITY_USER: User approval required at minimum
  43  * @TB_SECURITY_SECURE: One time saved key required at minimum
  44  * @TB_SECURITY_DPONLY: Only tunnel Display port (and USB)
  45  * @TB_SECURITY_USBONLY: Only tunnel USB controller of the connected
  46  *                       Thunderbolt dock (and Display Port). All PCIe
  47  *                       links downstream of the dock are removed.
  48  */
  49 enum tb_security_level {
  50         TB_SECURITY_NONE,
  51         TB_SECURITY_USER,
  52         TB_SECURITY_SECURE,
  53         TB_SECURITY_DPONLY,
  54         TB_SECURITY_USBONLY,
  55 };
  56
  57 /**
  58  * struct tb - main thunderbolt bus structure
  59  * @dev: Domain device
  60  * @lock: Big lock. Must be held when accessing any struct
  61  *        tb_switch / struct tb_port.
  62  * @nhi: Pointer to the NHI structure
  63  * @ctl: Control channel for this domain
  64  * @wq: Ordered workqueue for all domain specific work
  65  * @root_switch: Root switch of this domain
  66  * @cm_ops: Connection manager specific operations vector
  67  * @index: Linux assigned domain number
  68  * @security_level: Current security level
  69  * @nboot_acl: Number of boot ACLs the domain supports
  70  * @privdata: Private connection manager specific data
  71  */
  72 struct tb {
  73         struct device dev;
  74         struct mutex lock;
  75         struct tb_nhi *nhi;
  76         struct tb_ctl *ctl;
  77         struct workqueue_struct *wq;
  78         struct tb_switch *root_switch;
  79         const struct tb_cm_ops *cm_ops;
  80         int index;
  81         enum tb_security_level security_level;
  82         size_t nboot_acl;
  83         unsigned long privdata[0];
  84 };
  85
  86 extern struct bus_type tb_bus_type;
  87 extern struct device_type tb_service_type;
  88 extern struct device_type tb_xdomain_type;
  89
  90 #define TB_LINKS_PER_PHY_PORT   2
  91
  92 static inline unsigned int tb_phy_port_from_link(unsigned int link)
  93 {
  94         return (link - 1) / TB_LINKS_PER_PHY_PORT;
  95 }
  96
  97 /**
  98  * struct tb_property_dir - XDomain property directory
  99  * @uuid: Directory UUID or %NULL if root directory
 100  * @properties: List of properties in this directory
 101  *
 102  * User needs to provide serialization if needed.
 103  */
 104 struct tb_property_dir {
 105         const uuid_t *uuid;
 106         struct list_head properties;
 107 };
 108
 109 enum tb_property_type {
 110         TB_PROPERTY_TYPE_UNKNOWN = 0x00,
 111         TB_PROPERTY_TYPE_DIRECTORY = 0x44,
 112         TB_PROPERTY_TYPE_DATA = 0x64,
 113         TB_PROPERTY_TYPE_TEXT = 0x74,
 114         TB_PROPERTY_TYPE_VALUE = 0x76,
 115 };
 116
 117 #define TB_PROPERTY_KEY_SIZE    8
 118
 119 /**
 120  * struct tb_property - XDomain property
 121  * @list: Used to link properties together in a directory
 122  * @key: Key for the property (always terminated).
 123  * @type: Type of the property
 124  * @length: Length of the property data in dwords
 125  * @value: Property value
 126  *
 127  * Users use @type to determine which field in @value is filled.
 128  */
 129 struct tb_property {
 130         struct list_head list;
 131         char key[TB_PROPERTY_KEY_SIZE + 1];
 132         enum tb_property_type type;
 133         size_t length;
 134         union {
 135                 struct tb_property_dir *dir;
 136                 u8 *data;
 137                 char *text;
 138                 u32 immediate;
 139         } value;
 140 };
 141
 142 struct tb_property_dir *tb_property_parse_dir(const u32 *block,
 143                                               size_t block_len);
 144 ssize_t tb_property_format_dir(const struct tb_property_dir *dir, u32 *block,
 145                                size_t block_len);
 146 struct tb_property_dir *tb_property_create_dir(const uuid_t *uuid);
 147 void tb_property_free_dir(struct tb_property_dir *dir);
 148 int tb_property_add_immediate(struct tb_property_dir *parent, const char *key,
 149                               u32 value);
 150 int tb_property_add_data(struct tb_property_dir *parent, const char *key,
 151                          const void *buf, size_t buflen);
 152 int tb_property_add_text(struct tb_property_dir *parent, const char *key,
 153                          const char *text);
 154 int tb_property_add_dir(struct tb_property_dir *parent, const char *key,
 155                         struct tb_property_dir *dir);
 156 void tb_property_remove(struct tb_property *tb_property);
 157 struct tb_property *tb_property_find(struct tb_property_dir *dir,
 158                         const char *key, enum tb_property_type type);
 159 struct tb_property *tb_property_get_next(struct tb_property_dir *dir,
 160                                          struct tb_property *prev);
 161
 162 #define tb_property_for_each(dir, property)                     \
 163         for (property = tb_property_get_next(dir, NULL);        \
 164              property;                                          \
 165              property = tb_property_get_next(dir, property))
 166
 167 int tb_register_property_dir(const char *key, struct tb_property_dir *dir);
 168 void tb_unregister_property_dir(const char *key, struct tb_property_dir *dir);
 169
 170 /**
 171  * struct tb_xdomain - Cross-domain (XDomain) connection
 172  * @dev: XDomain device
 173  * @tb: Pointer to the domain
 174  * @remote_uuid: UUID of the remote domain (host)
 175  * @local_uuid: Cached local UUID
 176  * @route: Route string the other domain can be reached
 177  * @vendor: Vendor ID of the remote domain
 178  * @device: Device ID of the demote domain
 179  * @lock: Lock to serialize access to the following fields of this structure
 180  * @vendor_name: Name of the vendor (or %NULL if not known)
 181  * @device_name: Name of the device (or %NULL if not known)
 182  * @is_unplugged: The XDomain is unplugged
 183  * @resume: The XDomain is being resumed
 184  * @transmit_path: HopID which the remote end expects us to transmit
 185  * @transmit_ring: Local ring (hop) where outgoing packets are pushed
 186  * @receive_path: HopID which we expect the remote end to transmit
 187  * @receive_ring: Local ring (hop) where incoming packets arrive
 188  * @service_ids: Used to generate IDs for the services
 189  * @properties: Properties exported by the remote domain
 190  * @property_block_gen: Generation of @properties
 191  * @properties_lock: Lock protecting @properties.
 192  * @get_properties_work: Work used to get remote domain properties
 193  * @properties_retries: Number of times left to read properties
 194  * @properties_changed_work: Work used to notify the remote domain that
 195  *                           our properties have changed
 196  * @properties_changed_retries: Number of times left to send properties
 197  *                              changed notification
 198  * @link: Root switch link the remote domain is connected (ICM only)
 199  * @depth: Depth in the chain the remote domain is connected (ICM only)
 200  *
 201  * This structure represents connection across two domains (hosts).
 202  * Each XDomain contains zero or more services which are exposed as
 203  * &struct tb_service objects.
 204  *
 205  * Service drivers may access this structure if they need to enumerate
 206  * non-standard properties but they need hold @lock when doing so
 207  * because properties can be changed asynchronously in response to
 208  * changes in the remote domain.
 209  */
 210 struct tb_xdomain {
 211         struct device dev;
 212         struct tb *tb;
 213         uuid_t *remote_uuid;
 214         const uuid_t *local_uuid;
 215         u64 route;
 216         u16 vendor;
 217         u16 device;
 218         struct mutex lock;
 219         const char *vendor_name;
 220         const char *device_name;
 221         bool is_unplugged;
 222         bool resume;
 223         u16 transmit_path;
 224         u16 transmit_ring;
 225         u16 receive_path;
 226         u16 receive_ring;
 227         struct ida service_ids;
 228         struct tb_property_dir *properties;
 229         u32 property_block_gen;
 230         struct delayed_work get_properties_work;
 231         int properties_retries;
 232         struct delayed_work properties_changed_work;
 233         int properties_changed_retries;
 234         u8 link;
 235         u8 depth;
 236 };
 237
 238 int tb_xdomain_enable_paths(struct tb_xdomain *xd, u16 transmit_path,
 239                             u16 transmit_ring, u16 receive_path,
 240                             u16 receive_ring);
 241 int tb_xdomain_disable_paths(struct tb_xdomain *xd);
 242 struct tb_xdomain *tb_xdomain_find_by_uuid(struct tb *tb, const uuid_t *uuid);
 243 struct tb_xdomain *tb_xdomain_find_by_route(struct tb *tb, u64 route);
 244
 245 static inline struct tb_xdomain *
 246 tb_xdomain_find_by_uuid_locked(struct tb *tb, const uuid_t *uuid)
 247 {
 248         struct tb_xdomain *xd;
 249
 250         mutex_lock(&tb->lock);
 251         xd = tb_xdomain_find_by_uuid(tb, uuid);
 252         mutex_unlock(&tb->lock);
 253
 254         return xd;
 255 }
 256
 257 static inline struct tb_xdomain *
 258 tb_xdomain_find_by_route_locked(struct tb *tb, u64 route)
 259 {
 260         struct tb_xdomain *xd;
 261
 262         mutex_lock(&tb->lock);
 263         xd = tb_xdomain_find_by_route(tb, route);
 264         mutex_unlock(&tb->lock);
 265
 266         return xd;
 267 }
 268
 269 static inline struct tb_xdomain *tb_xdomain_get(struct tb_xdomain *xd)
 270 {
 271         if (xd)
 272                 get_device(&xd->dev);
 273         return xd;
 274 }
 275
 276 static inline void tb_xdomain_put(struct tb_xdomain *xd)
 277 {
 278         if (xd)
 279                 put_device(&xd->dev);
 280 }
 281
 282 static inline bool tb_is_xdomain(const struct device *dev)
 283 {
 284         return dev->type == &tb_xdomain_type;
 285 }
 286
 287 static inline struct tb_xdomain *tb_to_xdomain(struct device *dev)
 288 {
 289         if (tb_is_xdomain(dev))
 290                 return container_of(dev, struct tb_xdomain, dev);
 291         return NULL;
 292 }
 293
 294 int tb_xdomain_response(struct tb_xdomain *xd, const void *response,
 295                         size_t size, enum tb_cfg_pkg_type type);
 296 int tb_xdomain_request(struct tb_xdomain *xd, const void *request,
 297                        size_t request_size, enum tb_cfg_pkg_type request_type,
 298                        void *response, size_t response_size,
 299                        enum tb_cfg_pkg_type response_type,
 300                        unsigned int timeout_msec);
 301
 302 /**
 303  * tb_protocol_handler - Protocol specific handler
 304  * @uuid: XDomain messages with this UUID are dispatched to this handler
 305  * @callback: Callback called with the XDomain message. Returning %1
 306  *            here tells the XDomain core that the message was handled
 307  *            by this handler and should not be forwared to other
 308  *            handlers.
 309  * @data: Data passed with the callback
 310  * @list: Handlers are linked using this
 311  *
 312  * Thunderbolt services can hook into incoming XDomain requests by
 313  * registering protocol handler. Only limitation is that the XDomain
 314  * discovery protocol UUID cannot be registered since it is handled by
 315  * the core XDomain code.
 316  *
 317  * The @callback must check that the message is really directed to the
 318  * service the driver implements.
 319  */
 320 struct tb_protocol_handler {
 321         const uuid_t *uuid;
 322         int (*callback)(const void *buf, size_t size, void *data);
 323         void *data;
 324         struct list_head list;
 325 };
 326
 327 int tb_register_protocol_handler(struct tb_protocol_handler *handler);
 328 void tb_unregister_protocol_handler(struct tb_protocol_handler *handler);
 329
 330 /**
 331  * struct tb_service - Thunderbolt service
 332  * @dev: XDomain device
 333  * @id: ID of the service (shown in sysfs)
 334  * @key: Protocol key from the properties directory
 335  * @prtcid: Protocol ID from the properties directory
 336  * @prtcvers: Protocol version from the properties directory
 337  * @prtcrevs: Protocol software revision from the properties directory
 338  * @prtcstns: Protocol settings mask from the properties directory
 339  *
 340  * Each domain exposes set of services it supports as collection of
 341  * properties. For each service there will be one corresponding
 342  * &struct tb_service. Service drivers are bound to these.
 343  */
 344 struct tb_service {
 345         struct device dev;
 346         int id;
 347         const char *key;
 348         u32 prtcid;
 349         u32 prtcvers;
 350         u32 prtcrevs;
 351         u32 prtcstns;
 352 };
 353
 354 static inline struct tb_service *tb_service_get(struct tb_service *svc)
 355 {
 356         if (svc)
 357                 get_device(&svc->dev);
 358         return svc;
 359 }
 360
 361 static inline void tb_service_put(struct tb_service *svc)
 362 {
 363         if (svc)
 364                 put_device(&svc->dev);
 365 }
 366
 367 static inline bool tb_is_service(const struct device *dev)
 368 {
 369         return dev->type == &tb_service_type;
 370 }
 371
 372 static inline struct tb_service *tb_to_service(struct device *dev)
 373 {
 374         if (tb_is_service(dev))
 375                 return container_of(dev, struct tb_service, dev);
 376         return NULL;
 377 }
 378
 379 /**
 380  * tb_service_driver - Thunderbolt service driver
 381  * @driver: Driver structure
 382  * @probe: Called when the driver is probed
 383  * @remove: Called when the driver is removed (optional)
 384  * @shutdown: Called at shutdown time to stop the service (optional)
 385  * @id_table: Table of service identifiers the driver supports
 386  */
 387 struct tb_service_driver {
 388         struct device_driver driver;
 389         int (*probe)(struct tb_service *svc, const struct tb_service_id *id);
 390         void (*remove)(struct tb_service *svc);
 391         void (*shutdown)(struct tb_service *svc);
 392         const struct tb_service_id *id_table;
 393 };
 394
 395 #define TB_SERVICE(key, id)                             \
 396         .match_flags = TBSVC_MATCH_PROTOCOL_KEY |       \
 397                        TBSVC_MATCH_PROTOCOL_ID,         \
 398         .protocol_key = (key),                          \
 399         .protocol_id = (id)
 400
 401 int tb_register_service_driver(struct tb_service_driver *drv);
 402 void tb_unregister_service_driver(struct tb_service_driver *drv);
 403
 404 static inline void *tb_service_get_drvdata(const struct tb_service *svc)
 405 {
 406         return dev_get_drvdata(&svc->dev);
 407 }
 408
 409 static inline void tb_service_set_drvdata(struct tb_service *svc, void *data)
 410 {
 411         dev_set_drvdata(&svc->dev, data);
 412 }
 413
 414 static inline struct tb_xdomain *tb_service_parent(struct tb_service *svc)
 415 {
 416         return tb_to_xdomain(svc->dev.parent);
 417 }
 418
 419 /**
 420  * struct tb_nhi - thunderbolt native host interface
 421  * @lock: Must be held during ring creation/destruction. Is acquired by
 422  *        interrupt_work when dispatching interrupts to individual rings.
 423  * @pdev: Pointer to the PCI device
 424  * @iobase: MMIO space of the NHI
 425  * @tx_rings: All Tx rings available on this host controller
 426  * @rx_rings: All Rx rings available on this host controller
 427  * @msix_ida: Used to allocate MSI-X vectors for rings
 428  * @going_away: The host controller device is about to disappear so when
 429  *              this flag is set, avoid touching the hardware anymore.
 430  * @interrupt_work: Work scheduled to handle ring interrupt when no
 431  *                  MSI-X is used.
 432  * @hop_count: Number of rings (end point hops) supported by NHI.
 433  */
 434 struct tb_nhi {
 435         spinlock_t lock;
 436         struct pci_dev *pdev;
 437         void __iomem *iobase;
 438         struct tb_ring **tx_rings;
 439         struct tb_ring **rx_rings;
 440         struct ida msix_ida;
 441         bool going_away;
 442         struct work_struct interrupt_work;
 443         u32 hop_count;
 444 };
 445
 446 /**
 447  * struct tb_ring - thunderbolt TX or RX ring associated with a NHI
 448  * @lock: Lock serializing actions to this ring. Must be acquired after
 449  *        nhi->lock.
 450  * @nhi: Pointer to the native host controller interface
 451  * @size: Size of the ring
 452  * @hop: Hop (DMA channel) associated with this ring
 453  * @head: Head of the ring (write next descriptor here)
 454  * @tail: Tail of the ring (complete next descriptor here)
 455  * @descriptors: Allocated descriptors for this ring
 456  * @queue: Queue holding frames to be transferred over this ring
 457  * @in_flight: Queue holding frames that are currently in flight
 458  * @work: Interrupt work structure
 459  * @is_tx: Is the ring Tx or Rx
 460  * @running: Is the ring running
 461  * @irq: MSI-X irq number if the ring uses MSI-X. %0 otherwise.
 462  * @vector: MSI-X vector number the ring uses (only set if @irq is > 0)
 463  * @flags: Ring specific flags
 464  * @sof_mask: Bit mask used to detect start of frame PDF
 465  * @eof_mask: Bit mask used to detect end of frame PDF
 466  * @start_poll: Called when ring interrupt is triggered to start
 467  *              polling. Passing %NULL keeps the ring in interrupt mode.
 468  * @poll_data: Data passed to @start_poll
 469  */
 470 struct tb_ring {
 471         spinlock_t lock;
 472         struct tb_nhi *nhi;
 473         int size;
 474         int hop;
 475         int head;
 476         int tail;
 477         struct ring_desc *descriptors;
 478         dma_addr_t descriptors_dma;
 479         struct list_head queue;
 480         struct list_head in_flight;
 481         struct work_struct work;
 482         bool is_tx:1;
 483         bool running:1;
 484         int irq;
 485         u8 vector;
 486         unsigned int flags;
 487         u16 sof_mask;
 488         u16 eof_mask;
 489         void (*start_poll)(void *data);
 490         void *poll_data;
 491 };
 492
 493 /* Leave ring interrupt enabled on suspend */
 494 #define RING_FLAG_NO_SUSPEND    BIT(0)
 495 /* Configure the ring to be in frame mode */
 496 #define RING_FLAG_FRAME         BIT(1)
 497 /* Enable end-to-end flow control */
 498 #define RING_FLAG_E2E           BIT(2)
 499
 500 struct ring_frame;
 501 typedef void (*ring_cb)(struct tb_ring *, struct ring_frame *, bool canceled);
 502
 503 /**
 504  * enum ring_desc_flags - Flags for DMA ring descriptor
 505  * %RING_DESC_ISOCH: Enable isonchronous DMA (Tx only)
 506  * %RING_DESC_CRC_ERROR: In frame mode CRC check failed for the frame (Rx only)
 507  * %RING_DESC_COMPLETED: Descriptor completed (set by NHI)
 508  * %RING_DESC_POSTED: Always set this
 509  * %RING_DESC_BUFFER_OVERRUN: RX buffer overrun
 510  * %RING_DESC_INTERRUPT: Request an interrupt on completion
 511  */
 512 enum ring_desc_flags {
 513         RING_DESC_ISOCH = 0x1,
 514         RING_DESC_CRC_ERROR = 0x1,
 515         RING_DESC_COMPLETED = 0x2,
 516         RING_DESC_POSTED = 0x4,
 517         RING_DESC_BUFFER_OVERRUN = 0x04,
 518         RING_DESC_INTERRUPT = 0x8,
 519 };
 520
 521 /**
 522  * struct ring_frame - For use with ring_rx/ring_tx
 523  * @buffer_phy: DMA mapped address of the frame
 524  * @callback: Callback called when the frame is finished (optional)
 525  * @list: Frame is linked to a queue using this
 526  * @size: Size of the frame in bytes (%0 means %4096)
 527  * @flags: Flags for the frame (see &enum ring_desc_flags)
 528  * @eof: End of frame protocol defined field
 529  * @sof: Start of frame protocol defined field
 530  */
 531 struct ring_frame {
 532         dma_addr_t buffer_phy;
 533         ring_cb callback;
 534         struct list_head list;
 535         u32 size:12;
 536         u32 flags:12;
 537         u32 eof:4;
 538         u32 sof:4;
 539 };
 540
 541 /* Minimum size for ring_rx */
 542 #define TB_FRAME_SIZE           0x100
 543
 544 struct tb_ring *tb_ring_alloc_tx(struct tb_nhi *nhi, int hop, int size,
 545                                  unsigned int flags);
 546 struct tb_ring *tb_ring_alloc_rx(struct tb_nhi *nhi, int hop, int size,
 547                                  unsigned int flags, u16 sof_mask, u16 eof_mask,
 548                                  void (*start_poll)(void *), void *poll_data);
 549 void tb_ring_start(struct tb_ring *ring);
 550 void tb_ring_stop(struct tb_ring *ring);
 551 void tb_ring_free(struct tb_ring *ring);
 552
 553 int __tb_ring_enqueue(struct tb_ring *ring, struct ring_frame *frame);
 554
 555 /**
 556  * tb_ring_rx() - enqueue a frame on an RX ring
 557  * @ring: Ring to enqueue the frame
 558  * @frame: Frame to enqueue
 559  *
 560  * @frame->buffer, @frame->buffer_phy have to be set. The buffer must
 561  * contain at least %TB_FRAME_SIZE bytes.
 562  *
 563  * @frame->callback will be invoked with @frame->size, @frame->flags,
 564  * @frame->eof, @frame->sof set once the frame has been received.
 565  *
 566  * If ring_stop() is called after the packet has been enqueued
 567  * @frame->callback will be called with canceled set to true.
 568  *
 569  * Return: Returns %-ESHUTDOWN if ring_stop has been called. Zero otherwise.
 570  */
 571 static inline int tb_ring_rx(struct tb_ring *ring, struct ring_frame *frame)
 572 {
 573         WARN_ON(ring->is_tx);
 574         return __tb_ring_enqueue(ring, frame);
 575 }
 576
 577 /**
 578  * tb_ring_tx() - enqueue a frame on an TX ring
 579  * @ring: Ring the enqueue the frame
 580  * @frame: Frame to enqueue
 581  *
 582  * @frame->buffer, @frame->buffer_phy, @frame->size, @frame->eof and
 583  * @frame->sof have to be set.
 584  *
 585  * @frame->callback will be invoked with once the frame has been transmitted.
 586  *
 587  * If ring_stop() is called after the packet has been enqueued @frame->callback
 588  * will be called with canceled set to true.
 589  *
 590  * Return: Returns %-ESHUTDOWN if ring_stop has been called. Zero otherwise.
 591  */
 592 static inline int tb_ring_tx(struct tb_ring *ring, struct ring_frame *frame)
 593 {
 594         WARN_ON(!ring->is_tx);
 595         return __tb_ring_enqueue(ring, frame);
 596 }
 597
 598 /* Used only when the ring is in polling mode */
 599 struct ring_frame *tb_ring_poll(struct tb_ring *ring);
 600 void tb_ring_poll_complete(struct tb_ring *ring);
 601
 602 /**
 603  * tb_ring_dma_device() - Return device used for DMA mapping
 604  * @ring: Ring whose DMA device is retrieved
 605  *
 606  * Use this function when you are mapping DMA for buffers that are
 607  * passed to the ring for sending/receiving.
 608  */
 609 static inline struct device *tb_ring_dma_device(struct tb_ring *ring)
 610 {
 611         return &ring->nhi->pdev->dev;
 612 }
 613
 614 #endif /* THUNDERBOLT_H_ */