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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[];
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 
tb_phy_port_from_link(unsigned int link)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  * @needs_uuid: If the XDomain does not have @remote_uuid it will be
185  *		queried first
186  * @transmit_path: HopID which the remote end expects us to transmit
187  * @transmit_ring: Local ring (hop) where outgoing packets are pushed
188  * @receive_path: HopID which we expect the remote end to transmit
189  * @receive_ring: Local ring (hop) where incoming packets arrive
190  * @service_ids: Used to generate IDs for the services
191  * @properties: Properties exported by the remote domain
192  * @property_block_gen: Generation of @properties
193  * @properties_lock: Lock protecting @properties.
194  * @get_uuid_work: Work used to retrieve @remote_uuid
195  * @uuid_retries: Number of times left @remote_uuid is requested before
196  *		  giving up
197  * @get_properties_work: Work used to get remote domain properties
198  * @properties_retries: Number of times left to read properties
199  * @properties_changed_work: Work used to notify the remote domain that
200  *			     our properties have changed
201  * @properties_changed_retries: Number of times left to send properties
202  *				changed notification
203  * @link: Root switch link the remote domain is connected (ICM only)
204  * @depth: Depth in the chain the remote domain is connected (ICM only)
205  *
206  * This structure represents connection across two domains (hosts).
207  * Each XDomain contains zero or more services which are exposed as
208  * &struct tb_service objects.
209  *
210  * Service drivers may access this structure if they need to enumerate
211  * non-standard properties but they need hold @lock when doing so
212  * because properties can be changed asynchronously in response to
213  * changes in the remote domain.
214  */
215 struct tb_xdomain {
216 	struct device dev;
217 	struct tb *tb;
218 	uuid_t *remote_uuid;
219 	const uuid_t *local_uuid;
220 	u64 route;
221 	u16 vendor;
222 	u16 device;
223 	struct mutex lock;
224 	const char *vendor_name;
225 	const char *device_name;
226 	bool is_unplugged;
227 	bool resume;
228 	bool needs_uuid;
229 	u16 transmit_path;
230 	u16 transmit_ring;
231 	u16 receive_path;
232 	u16 receive_ring;
233 	struct ida service_ids;
234 	struct tb_property_dir *properties;
235 	u32 property_block_gen;
236 	struct delayed_work get_uuid_work;
237 	int uuid_retries;
238 	struct delayed_work get_properties_work;
239 	int properties_retries;
240 	struct delayed_work properties_changed_work;
241 	int properties_changed_retries;
242 	u8 link;
243 	u8 depth;
244 };
245 
246 int tb_xdomain_enable_paths(struct tb_xdomain *xd, u16 transmit_path,
247 			    u16 transmit_ring, u16 receive_path,
248 			    u16 receive_ring);
249 int tb_xdomain_disable_paths(struct tb_xdomain *xd);
250 struct tb_xdomain *tb_xdomain_find_by_uuid(struct tb *tb, const uuid_t *uuid);
251 struct tb_xdomain *tb_xdomain_find_by_route(struct tb *tb, u64 route);
252 
253 static inline struct tb_xdomain *
tb_xdomain_find_by_uuid_locked(struct tb * tb,const uuid_t * uuid)254 tb_xdomain_find_by_uuid_locked(struct tb *tb, const uuid_t *uuid)
255 {
256 	struct tb_xdomain *xd;
257 
258 	mutex_lock(&tb->lock);
259 	xd = tb_xdomain_find_by_uuid(tb, uuid);
260 	mutex_unlock(&tb->lock);
261 
262 	return xd;
263 }
264 
265 static inline struct tb_xdomain *
tb_xdomain_find_by_route_locked(struct tb * tb,u64 route)266 tb_xdomain_find_by_route_locked(struct tb *tb, u64 route)
267 {
268 	struct tb_xdomain *xd;
269 
270 	mutex_lock(&tb->lock);
271 	xd = tb_xdomain_find_by_route(tb, route);
272 	mutex_unlock(&tb->lock);
273 
274 	return xd;
275 }
276 
tb_xdomain_get(struct tb_xdomain * xd)277 static inline struct tb_xdomain *tb_xdomain_get(struct tb_xdomain *xd)
278 {
279 	if (xd)
280 		get_device(&xd->dev);
281 	return xd;
282 }
283 
tb_xdomain_put(struct tb_xdomain * xd)284 static inline void tb_xdomain_put(struct tb_xdomain *xd)
285 {
286 	if (xd)
287 		put_device(&xd->dev);
288 }
289 
tb_is_xdomain(const struct device * dev)290 static inline bool tb_is_xdomain(const struct device *dev)
291 {
292 	return dev->type == &tb_xdomain_type;
293 }
294 
tb_to_xdomain(struct device * dev)295 static inline struct tb_xdomain *tb_to_xdomain(struct device *dev)
296 {
297 	if (tb_is_xdomain(dev))
298 		return container_of(dev, struct tb_xdomain, dev);
299 	return NULL;
300 }
301 
302 int tb_xdomain_response(struct tb_xdomain *xd, const void *response,
303 			size_t size, enum tb_cfg_pkg_type type);
304 int tb_xdomain_request(struct tb_xdomain *xd, const void *request,
305 		       size_t request_size, enum tb_cfg_pkg_type request_type,
306 		       void *response, size_t response_size,
307 		       enum tb_cfg_pkg_type response_type,
308 		       unsigned int timeout_msec);
309 
310 /**
311  * tb_protocol_handler - Protocol specific handler
312  * @uuid: XDomain messages with this UUID are dispatched to this handler
313  * @callback: Callback called with the XDomain message. Returning %1
314  *	      here tells the XDomain core that the message was handled
315  *	      by this handler and should not be forwared to other
316  *	      handlers.
317  * @data: Data passed with the callback
318  * @list: Handlers are linked using this
319  *
320  * Thunderbolt services can hook into incoming XDomain requests by
321  * registering protocol handler. Only limitation is that the XDomain
322  * discovery protocol UUID cannot be registered since it is handled by
323  * the core XDomain code.
324  *
325  * The @callback must check that the message is really directed to the
326  * service the driver implements.
327  */
328 struct tb_protocol_handler {
329 	const uuid_t *uuid;
330 	int (*callback)(const void *buf, size_t size, void *data);
331 	void *data;
332 	struct list_head list;
333 };
334 
335 int tb_register_protocol_handler(struct tb_protocol_handler *handler);
336 void tb_unregister_protocol_handler(struct tb_protocol_handler *handler);
337 
338 /**
339  * struct tb_service - Thunderbolt service
340  * @dev: XDomain device
341  * @id: ID of the service (shown in sysfs)
342  * @key: Protocol key from the properties directory
343  * @prtcid: Protocol ID from the properties directory
344  * @prtcvers: Protocol version from the properties directory
345  * @prtcrevs: Protocol software revision from the properties directory
346  * @prtcstns: Protocol settings mask from the properties directory
347  *
348  * Each domain exposes set of services it supports as collection of
349  * properties. For each service there will be one corresponding
350  * &struct tb_service. Service drivers are bound to these.
351  */
352 struct tb_service {
353 	struct device dev;
354 	int id;
355 	const char *key;
356 	u32 prtcid;
357 	u32 prtcvers;
358 	u32 prtcrevs;
359 	u32 prtcstns;
360 };
361 
tb_service_get(struct tb_service * svc)362 static inline struct tb_service *tb_service_get(struct tb_service *svc)
363 {
364 	if (svc)
365 		get_device(&svc->dev);
366 	return svc;
367 }
368 
tb_service_put(struct tb_service * svc)369 static inline void tb_service_put(struct tb_service *svc)
370 {
371 	if (svc)
372 		put_device(&svc->dev);
373 }
374 
tb_is_service(const struct device * dev)375 static inline bool tb_is_service(const struct device *dev)
376 {
377 	return dev->type == &tb_service_type;
378 }
379 
tb_to_service(struct device * dev)380 static inline struct tb_service *tb_to_service(struct device *dev)
381 {
382 	if (tb_is_service(dev))
383 		return container_of(dev, struct tb_service, dev);
384 	return NULL;
385 }
386 
387 /**
388  * tb_service_driver - Thunderbolt service driver
389  * @driver: Driver structure
390  * @probe: Called when the driver is probed
391  * @remove: Called when the driver is removed (optional)
392  * @shutdown: Called at shutdown time to stop the service (optional)
393  * @id_table: Table of service identifiers the driver supports
394  */
395 struct tb_service_driver {
396 	struct device_driver driver;
397 	int (*probe)(struct tb_service *svc, const struct tb_service_id *id);
398 	void (*remove)(struct tb_service *svc);
399 	void (*shutdown)(struct tb_service *svc);
400 	const struct tb_service_id *id_table;
401 };
402 
403 #define TB_SERVICE(key, id)				\
404 	.match_flags = TBSVC_MATCH_PROTOCOL_KEY |	\
405 		       TBSVC_MATCH_PROTOCOL_ID,		\
406 	.protocol_key = (key),				\
407 	.protocol_id = (id)
408 
409 int tb_register_service_driver(struct tb_service_driver *drv);
410 void tb_unregister_service_driver(struct tb_service_driver *drv);
411 
tb_service_get_drvdata(const struct tb_service * svc)412 static inline void *tb_service_get_drvdata(const struct tb_service *svc)
413 {
414 	return dev_get_drvdata(&svc->dev);
415 }
416 
tb_service_set_drvdata(struct tb_service * svc,void * data)417 static inline void tb_service_set_drvdata(struct tb_service *svc, void *data)
418 {
419 	dev_set_drvdata(&svc->dev, data);
420 }
421 
tb_service_parent(struct tb_service * svc)422 static inline struct tb_xdomain *tb_service_parent(struct tb_service *svc)
423 {
424 	return tb_to_xdomain(svc->dev.parent);
425 }
426 
427 /**
428  * struct tb_nhi - thunderbolt native host interface
429  * @lock: Must be held during ring creation/destruction. Is acquired by
430  *	  interrupt_work when dispatching interrupts to individual rings.
431  * @pdev: Pointer to the PCI device
432  * @ops: NHI specific optional ops
433  * @iobase: MMIO space of the NHI
434  * @tx_rings: All Tx rings available on this host controller
435  * @rx_rings: All Rx rings available on this host controller
436  * @msix_ida: Used to allocate MSI-X vectors for rings
437  * @going_away: The host controller device is about to disappear so when
438  *		this flag is set, avoid touching the hardware anymore.
439  * @interrupt_work: Work scheduled to handle ring interrupt when no
440  *		    MSI-X is used.
441  * @hop_count: Number of rings (end point hops) supported by NHI.
442  */
443 struct tb_nhi {
444 	spinlock_t lock;
445 	struct pci_dev *pdev;
446 	const struct tb_nhi_ops *ops;
447 	void __iomem *iobase;
448 	struct tb_ring **tx_rings;
449 	struct tb_ring **rx_rings;
450 	struct ida msix_ida;
451 	bool going_away;
452 	struct work_struct interrupt_work;
453 	u32 hop_count;
454 };
455 
456 /**
457  * struct tb_ring - thunderbolt TX or RX ring associated with a NHI
458  * @lock: Lock serializing actions to this ring. Must be acquired after
459  *	  nhi->lock.
460  * @nhi: Pointer to the native host controller interface
461  * @size: Size of the ring
462  * @hop: Hop (DMA channel) associated with this ring
463  * @head: Head of the ring (write next descriptor here)
464  * @tail: Tail of the ring (complete next descriptor here)
465  * @descriptors: Allocated descriptors for this ring
466  * @queue: Queue holding frames to be transferred over this ring
467  * @in_flight: Queue holding frames that are currently in flight
468  * @work: Interrupt work structure
469  * @is_tx: Is the ring Tx or Rx
470  * @running: Is the ring running
471  * @irq: MSI-X irq number if the ring uses MSI-X. %0 otherwise.
472  * @vector: MSI-X vector number the ring uses (only set if @irq is > 0)
473  * @flags: Ring specific flags
474  * @sof_mask: Bit mask used to detect start of frame PDF
475  * @eof_mask: Bit mask used to detect end of frame PDF
476  * @start_poll: Called when ring interrupt is triggered to start
477  *		polling. Passing %NULL keeps the ring in interrupt mode.
478  * @poll_data: Data passed to @start_poll
479  */
480 struct tb_ring {
481 	spinlock_t lock;
482 	struct tb_nhi *nhi;
483 	int size;
484 	int hop;
485 	int head;
486 	int tail;
487 	struct ring_desc *descriptors;
488 	dma_addr_t descriptors_dma;
489 	struct list_head queue;
490 	struct list_head in_flight;
491 	struct work_struct work;
492 	bool is_tx:1;
493 	bool running:1;
494 	int irq;
495 	u8 vector;
496 	unsigned int flags;
497 	u16 sof_mask;
498 	u16 eof_mask;
499 	void (*start_poll)(void *data);
500 	void *poll_data;
501 };
502 
503 /* Leave ring interrupt enabled on suspend */
504 #define RING_FLAG_NO_SUSPEND	BIT(0)
505 /* Configure the ring to be in frame mode */
506 #define RING_FLAG_FRAME		BIT(1)
507 
508 struct ring_frame;
509 typedef void (*ring_cb)(struct tb_ring *, struct ring_frame *, bool canceled);
510 
511 /**
512  * enum ring_desc_flags - Flags for DMA ring descriptor
513  * %RING_DESC_ISOCH: Enable isonchronous DMA (Tx only)
514  * %RING_DESC_CRC_ERROR: In frame mode CRC check failed for the frame (Rx only)
515  * %RING_DESC_COMPLETED: Descriptor completed (set by NHI)
516  * %RING_DESC_POSTED: Always set this
517  * %RING_DESC_BUFFER_OVERRUN: RX buffer overrun
518  * %RING_DESC_INTERRUPT: Request an interrupt on completion
519  */
520 enum ring_desc_flags {
521 	RING_DESC_ISOCH = 0x1,
522 	RING_DESC_CRC_ERROR = 0x1,
523 	RING_DESC_COMPLETED = 0x2,
524 	RING_DESC_POSTED = 0x4,
525 	RING_DESC_BUFFER_OVERRUN = 0x04,
526 	RING_DESC_INTERRUPT = 0x8,
527 };
528 
529 /**
530  * struct ring_frame - For use with ring_rx/ring_tx
531  * @buffer_phy: DMA mapped address of the frame
532  * @callback: Callback called when the frame is finished (optional)
533  * @list: Frame is linked to a queue using this
534  * @size: Size of the frame in bytes (%0 means %4096)
535  * @flags: Flags for the frame (see &enum ring_desc_flags)
536  * @eof: End of frame protocol defined field
537  * @sof: Start of frame protocol defined field
538  */
539 struct ring_frame {
540 	dma_addr_t buffer_phy;
541 	ring_cb callback;
542 	struct list_head list;
543 	u32 size:12;
544 	u32 flags:12;
545 	u32 eof:4;
546 	u32 sof:4;
547 };
548 
549 /* Minimum size for ring_rx */
550 #define TB_FRAME_SIZE		0x100
551 
552 struct tb_ring *tb_ring_alloc_tx(struct tb_nhi *nhi, int hop, int size,
553 				 unsigned int flags);
554 struct tb_ring *tb_ring_alloc_rx(struct tb_nhi *nhi, int hop, int size,
555 				 unsigned int flags, u16 sof_mask, u16 eof_mask,
556 				 void (*start_poll)(void *), void *poll_data);
557 void tb_ring_start(struct tb_ring *ring);
558 void tb_ring_stop(struct tb_ring *ring);
559 void tb_ring_free(struct tb_ring *ring);
560 
561 int __tb_ring_enqueue(struct tb_ring *ring, struct ring_frame *frame);
562 
563 /**
564  * tb_ring_rx() - enqueue a frame on an RX ring
565  * @ring: Ring to enqueue the frame
566  * @frame: Frame to enqueue
567  *
568  * @frame->buffer, @frame->buffer_phy have to be set. The buffer must
569  * contain at least %TB_FRAME_SIZE bytes.
570  *
571  * @frame->callback will be invoked with @frame->size, @frame->flags,
572  * @frame->eof, @frame->sof set once the frame has been received.
573  *
574  * If ring_stop() is called after the packet has been enqueued
575  * @frame->callback will be called with canceled set to true.
576  *
577  * Return: Returns %-ESHUTDOWN if ring_stop has been called. Zero otherwise.
578  */
tb_ring_rx(struct tb_ring * ring,struct ring_frame * frame)579 static inline int tb_ring_rx(struct tb_ring *ring, struct ring_frame *frame)
580 {
581 	WARN_ON(ring->is_tx);
582 	return __tb_ring_enqueue(ring, frame);
583 }
584 
585 /**
586  * tb_ring_tx() - enqueue a frame on an TX ring
587  * @ring: Ring the enqueue the frame
588  * @frame: Frame to enqueue
589  *
590  * @frame->buffer, @frame->buffer_phy, @frame->size, @frame->eof and
591  * @frame->sof have to be set.
592  *
593  * @frame->callback will be invoked with once the frame has been transmitted.
594  *
595  * If ring_stop() is called after the packet has been enqueued @frame->callback
596  * will be called with canceled set to true.
597  *
598  * Return: Returns %-ESHUTDOWN if ring_stop has been called. Zero otherwise.
599  */
tb_ring_tx(struct tb_ring * ring,struct ring_frame * frame)600 static inline int tb_ring_tx(struct tb_ring *ring, struct ring_frame *frame)
601 {
602 	WARN_ON(!ring->is_tx);
603 	return __tb_ring_enqueue(ring, frame);
604 }
605 
606 /* Used only when the ring is in polling mode */
607 struct ring_frame *tb_ring_poll(struct tb_ring *ring);
608 void tb_ring_poll_complete(struct tb_ring *ring);
609 
610 /**
611  * tb_ring_dma_device() - Return device used for DMA mapping
612  * @ring: Ring whose DMA device is retrieved
613  *
614  * Use this function when you are mapping DMA for buffers that are
615  * passed to the ring for sending/receiving.
616  */
tb_ring_dma_device(struct tb_ring * ring)617 static inline struct device *tb_ring_dma_device(struct tb_ring *ring)
618 {
619 	return &ring->nhi->pdev->dev;
620 }
621 
622 #endif /* THUNDERBOLT_H_ */
623