1 /* SPDX-License-Identifier: GPL-2.0+ */
2 /*
3 * Surface Serial Hub (SSH) protocol and communication interface.
4 *
5 * Lower-level communication layers and SSH protocol definitions for the
6 * Surface System Aggregator Module (SSAM). Provides the interface for basic
7 * packet- and request-based communication with the SSAM EC via SSH.
8 *
9 * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
10 */
11
12 #ifndef _LINUX_SURFACE_AGGREGATOR_SERIAL_HUB_H
13 #define _LINUX_SURFACE_AGGREGATOR_SERIAL_HUB_H
14
15 #include <linux/crc-itu-t.h>
16 #include <linux/kref.h>
17 #include <linux/ktime.h>
18 #include <linux/list.h>
19 #include <linux/types.h>
20
21
22 /* -- Data structures for SAM-over-SSH communication. ----------------------- */
23
24 /**
25 * enum ssh_frame_type - Frame types for SSH frames.
26 *
27 * @SSH_FRAME_TYPE_DATA_SEQ:
28 * Indicates a data frame, followed by a payload with the length specified
29 * in the ``struct ssh_frame.len`` field. This frame is sequenced, meaning
30 * that an ACK is required.
31 *
32 * @SSH_FRAME_TYPE_DATA_NSQ:
33 * Same as %SSH_FRAME_TYPE_DATA_SEQ, but unsequenced, meaning that the
34 * message does not have to be ACKed.
35 *
36 * @SSH_FRAME_TYPE_ACK:
37 * Indicates an ACK message.
38 *
39 * @SSH_FRAME_TYPE_NAK:
40 * Indicates an error response for previously sent frame. In general, this
41 * means that the frame and/or payload is malformed, e.g. a CRC is wrong.
42 * For command-type payloads, this can also mean that the command is
43 * invalid.
44 */
45 enum ssh_frame_type {
46 SSH_FRAME_TYPE_DATA_SEQ = 0x80,
47 SSH_FRAME_TYPE_DATA_NSQ = 0x00,
48 SSH_FRAME_TYPE_ACK = 0x40,
49 SSH_FRAME_TYPE_NAK = 0x04,
50 };
51
52 /**
53 * struct ssh_frame - SSH communication frame.
54 * @type: The type of the frame. See &enum ssh_frame_type.
55 * @len: The length of the frame payload directly following the CRC for this
56 * frame. Does not include the final CRC for that payload.
57 * @seq: The sequence number for this message/exchange.
58 */
59 struct ssh_frame {
60 u8 type;
61 __le16 len;
62 u8 seq;
63 } __packed;
64
65 static_assert(sizeof(struct ssh_frame) == 4);
66
67 /*
68 * SSH_FRAME_MAX_PAYLOAD_SIZE - Maximum SSH frame payload length in bytes.
69 *
70 * This is the physical maximum length of the protocol. Implementations may
71 * set a more constrained limit.
72 */
73 #define SSH_FRAME_MAX_PAYLOAD_SIZE U16_MAX
74
75 /**
76 * enum ssh_payload_type - Type indicator for the SSH payload.
77 * @SSH_PLD_TYPE_CMD: The payload is a command structure with optional command
78 * payload.
79 */
80 enum ssh_payload_type {
81 SSH_PLD_TYPE_CMD = 0x80,
82 };
83
84 /**
85 * struct ssh_command - Payload of a command-type frame.
86 * @type: The type of the payload. See &enum ssh_payload_type. Should be
87 * SSH_PLD_TYPE_CMD for this struct.
88 * @tc: Command target category.
89 * @tid: Target ID. Indicates the target of the message.
90 * @sid: Source ID. Indicates the source of the message.
91 * @iid: Instance ID.
92 * @rqid: Request ID. Used to match requests with responses and differentiate
93 * between responses and events.
94 * @cid: Command ID.
95 */
96 struct ssh_command {
97 u8 type;
98 u8 tc;
99 u8 tid;
100 u8 sid;
101 u8 iid;
102 __le16 rqid;
103 u8 cid;
104 } __packed;
105
106 static_assert(sizeof(struct ssh_command) == 8);
107
108 /*
109 * SSH_COMMAND_MAX_PAYLOAD_SIZE - Maximum SSH command payload length in bytes.
110 *
111 * This is the physical maximum length of the protocol. Implementations may
112 * set a more constrained limit.
113 */
114 #define SSH_COMMAND_MAX_PAYLOAD_SIZE \
115 (SSH_FRAME_MAX_PAYLOAD_SIZE - sizeof(struct ssh_command))
116
117 /*
118 * SSH_MSG_LEN_BASE - Base-length of a SSH message.
119 *
120 * This is the minimum number of bytes required to form a message. The actual
121 * message length is SSH_MSG_LEN_BASE plus the length of the frame payload.
122 */
123 #define SSH_MSG_LEN_BASE (sizeof(struct ssh_frame) + 3ull * sizeof(u16))
124
125 /*
126 * SSH_MSG_LEN_CTRL - Length of a SSH control message.
127 *
128 * This is the length of a SSH control message, which is equal to a SSH
129 * message without any payload.
130 */
131 #define SSH_MSG_LEN_CTRL SSH_MSG_LEN_BASE
132
133 /**
134 * SSH_MESSAGE_LENGTH() - Compute length of SSH message.
135 * @payload_size: Length of the payload inside the SSH frame.
136 *
137 * Return: Returns the length of a SSH message with payload of specified size.
138 */
139 #define SSH_MESSAGE_LENGTH(payload_size) (SSH_MSG_LEN_BASE + (payload_size))
140
141 /**
142 * SSH_COMMAND_MESSAGE_LENGTH() - Compute length of SSH command message.
143 * @payload_size: Length of the command payload.
144 *
145 * Return: Returns the length of a SSH command message with command payload of
146 * specified size.
147 */
148 #define SSH_COMMAND_MESSAGE_LENGTH(payload_size) \
149 SSH_MESSAGE_LENGTH(sizeof(struct ssh_command) + (payload_size))
150
151 /**
152 * SSH_MSGOFFSET_FRAME() - Compute offset in SSH message to specified field in
153 * frame.
154 * @field: The field for which the offset should be computed.
155 *
156 * Return: Returns the offset of the specified &struct ssh_frame field in the
157 * raw SSH message data as. Takes SYN bytes (u16) preceding the frame into
158 * account.
159 */
160 #define SSH_MSGOFFSET_FRAME(field) \
161 (sizeof(u16) + offsetof(struct ssh_frame, field))
162
163 /**
164 * SSH_MSGOFFSET_COMMAND() - Compute offset in SSH message to specified field
165 * in command.
166 * @field: The field for which the offset should be computed.
167 *
168 * Return: Returns the offset of the specified &struct ssh_command field in
169 * the raw SSH message data. Takes SYN bytes (u16) preceding the frame and the
170 * frame CRC (u16) between frame and command into account.
171 */
172 #define SSH_MSGOFFSET_COMMAND(field) \
173 (2ull * sizeof(u16) + sizeof(struct ssh_frame) \
174 + offsetof(struct ssh_command, field))
175
176 /*
177 * SSH_MSG_SYN - SSH message synchronization (SYN) bytes as u16.
178 */
179 #define SSH_MSG_SYN ((u16)0x55aa)
180
181 /**
182 * ssh_crc() - Compute CRC for SSH messages.
183 * @buf: The pointer pointing to the data for which the CRC should be computed.
184 * @len: The length of the data for which the CRC should be computed.
185 *
186 * Return: Returns the CRC computed on the provided data, as used for SSH
187 * messages.
188 */
ssh_crc(const u8 * buf,size_t len)189 static inline u16 ssh_crc(const u8 *buf, size_t len)
190 {
191 return crc_itu_t(0xffff, buf, len);
192 }
193
194 /*
195 * SSH_NUM_EVENTS - The number of reserved event IDs.
196 *
197 * The number of reserved event IDs, used for registering an SSH event
198 * handler. Valid event IDs are numbers below or equal to this value, with
199 * exception of zero, which is not an event ID. Thus, this is also the
200 * absolute maximum number of event handlers that can be registered.
201 */
202 #define SSH_NUM_EVENTS 38
203
204 /*
205 * SSH_NUM_TARGETS - The number of communication targets used in the protocol.
206 */
207 #define SSH_NUM_TARGETS 2
208
209 /**
210 * ssh_rqid_next_valid() - Return the next valid request ID.
211 * @rqid: The current request ID.
212 *
213 * Return: Returns the next valid request ID, following the current request ID
214 * provided to this function. This function skips any request IDs reserved for
215 * events.
216 */
ssh_rqid_next_valid(u16 rqid)217 static inline u16 ssh_rqid_next_valid(u16 rqid)
218 {
219 return rqid > 0 ? rqid + 1u : rqid + SSH_NUM_EVENTS + 1u;
220 }
221
222 /**
223 * ssh_rqid_to_event() - Convert request ID to its corresponding event ID.
224 * @rqid: The request ID to convert.
225 */
ssh_rqid_to_event(u16 rqid)226 static inline u16 ssh_rqid_to_event(u16 rqid)
227 {
228 return rqid - 1u;
229 }
230
231 /**
232 * ssh_rqid_is_event() - Check if given request ID is a valid event ID.
233 * @rqid: The request ID to check.
234 */
ssh_rqid_is_event(u16 rqid)235 static inline bool ssh_rqid_is_event(u16 rqid)
236 {
237 return ssh_rqid_to_event(rqid) < SSH_NUM_EVENTS;
238 }
239
240 /**
241 * ssh_tc_to_rqid() - Convert target category to its corresponding request ID.
242 * @tc: The target category to convert.
243 */
ssh_tc_to_rqid(u8 tc)244 static inline u16 ssh_tc_to_rqid(u8 tc)
245 {
246 return tc;
247 }
248
249 /**
250 * ssh_tid_to_index() - Convert target ID to its corresponding target index.
251 * @tid: The target ID to convert.
252 */
ssh_tid_to_index(u8 tid)253 static inline u8 ssh_tid_to_index(u8 tid)
254 {
255 return tid - 1u;
256 }
257
258 /**
259 * ssh_tid_is_valid() - Check if target ID is valid/supported.
260 * @tid: The target ID to check.
261 */
ssh_tid_is_valid(u8 tid)262 static inline bool ssh_tid_is_valid(u8 tid)
263 {
264 return ssh_tid_to_index(tid) < SSH_NUM_TARGETS;
265 }
266
267 /**
268 * struct ssam_span - Reference to a buffer region.
269 * @ptr: Pointer to the buffer region.
270 * @len: Length of the buffer region.
271 *
272 * A reference to a (non-owned) buffer segment, consisting of pointer and
273 * length. Use of this struct indicates non-owned data, i.e. data of which the
274 * life-time is managed (i.e. it is allocated/freed) via another pointer.
275 */
276 struct ssam_span {
277 u8 *ptr;
278 size_t len;
279 };
280
281 /**
282 * enum ssam_ssh_tid - Target/source IDs for Serial Hub messages.
283 * @SSAM_SSH_TID_HOST: We as the kernel Serial Hub driver.
284 * @SSAM_SSH_TID_SAM: The Surface Aggregator EC.
285 * @SSAM_SSH_TID_KIP: Keyboard and perihperal controller.
286 * @SSAM_SSH_TID_DEBUG: Debug connector.
287 * @SSAM_SSH_TID_SURFLINK: SurfLink connector.
288 */
289 enum ssam_ssh_tid {
290 SSAM_SSH_TID_HOST = 0x00,
291 SSAM_SSH_TID_SAM = 0x01,
292 SSAM_SSH_TID_KIP = 0x02,
293 SSAM_SSH_TID_DEBUG = 0x03,
294 SSAM_SSH_TID_SURFLINK = 0x04,
295 };
296
297 /*
298 * Known SSH/EC target categories.
299 *
300 * List of currently known target category values; "Known" as in we know they
301 * exist and are valid on at least some device/model. Detailed functionality
302 * or the full category name is only known for some of these categories and
303 * is detailed in the respective comment below.
304 *
305 * These values and abbreviations have been extracted from strings inside the
306 * Windows driver.
307 */
308 enum ssam_ssh_tc {
309 /* Category 0x00 is invalid for EC use. */
310 SSAM_SSH_TC_SAM = 0x01, /* Generic system functionality, real-time clock. */
311 SSAM_SSH_TC_BAT = 0x02, /* Battery/power subsystem. */
312 SSAM_SSH_TC_TMP = 0x03, /* Thermal subsystem. */
313 SSAM_SSH_TC_PMC = 0x04,
314 SSAM_SSH_TC_FAN = 0x05,
315 SSAM_SSH_TC_PoM = 0x06,
316 SSAM_SSH_TC_DBG = 0x07,
317 SSAM_SSH_TC_KBD = 0x08, /* Legacy keyboard (Laptop 1/2). */
318 SSAM_SSH_TC_FWU = 0x09,
319 SSAM_SSH_TC_UNI = 0x0a,
320 SSAM_SSH_TC_LPC = 0x0b,
321 SSAM_SSH_TC_TCL = 0x0c,
322 SSAM_SSH_TC_SFL = 0x0d,
323 SSAM_SSH_TC_KIP = 0x0e, /* Manages detachable peripherals (Pro X/8 keyboard cover) */
324 SSAM_SSH_TC_EXT = 0x0f,
325 SSAM_SSH_TC_BLD = 0x10,
326 SSAM_SSH_TC_BAS = 0x11, /* Detachment system (Surface Book 2/3). */
327 SSAM_SSH_TC_SEN = 0x12,
328 SSAM_SSH_TC_SRQ = 0x13,
329 SSAM_SSH_TC_MCU = 0x14,
330 SSAM_SSH_TC_HID = 0x15, /* Generic HID input subsystem. */
331 SSAM_SSH_TC_TCH = 0x16,
332 SSAM_SSH_TC_BKL = 0x17,
333 SSAM_SSH_TC_TAM = 0x18,
334 SSAM_SSH_TC_ACC0 = 0x19,
335 SSAM_SSH_TC_UFI = 0x1a,
336 SSAM_SSH_TC_USC = 0x1b,
337 SSAM_SSH_TC_PEN = 0x1c,
338 SSAM_SSH_TC_VID = 0x1d,
339 SSAM_SSH_TC_AUD = 0x1e,
340 SSAM_SSH_TC_SMC = 0x1f,
341 SSAM_SSH_TC_KPD = 0x20,
342 SSAM_SSH_TC_REG = 0x21, /* Extended event registry. */
343 SSAM_SSH_TC_SPT = 0x22,
344 SSAM_SSH_TC_SYS = 0x23,
345 SSAM_SSH_TC_ACC1 = 0x24,
346 SSAM_SSH_TC_SHB = 0x25,
347 SSAM_SSH_TC_POS = 0x26, /* For obtaining Laptop Studio screen position. */
348 };
349
350
351 /* -- Packet transport layer (ptl). ----------------------------------------- */
352
353 /**
354 * enum ssh_packet_base_priority - Base priorities for &struct ssh_packet.
355 * @SSH_PACKET_PRIORITY_FLUSH: Base priority for flush packets.
356 * @SSH_PACKET_PRIORITY_DATA: Base priority for normal data packets.
357 * @SSH_PACKET_PRIORITY_NAK: Base priority for NAK packets.
358 * @SSH_PACKET_PRIORITY_ACK: Base priority for ACK packets.
359 */
360 enum ssh_packet_base_priority {
361 SSH_PACKET_PRIORITY_FLUSH = 0, /* same as DATA to sequence flush */
362 SSH_PACKET_PRIORITY_DATA = 0,
363 SSH_PACKET_PRIORITY_NAK = 1,
364 SSH_PACKET_PRIORITY_ACK = 2,
365 };
366
367 /*
368 * Same as SSH_PACKET_PRIORITY() below, only with actual values.
369 */
370 #define __SSH_PACKET_PRIORITY(base, try) \
371 (((base) << 4) | ((try) & 0x0f))
372
373 /**
374 * SSH_PACKET_PRIORITY() - Compute packet priority from base priority and
375 * number of tries.
376 * @base: The base priority as suffix of &enum ssh_packet_base_priority, e.g.
377 * ``FLUSH``, ``DATA``, ``ACK``, or ``NAK``.
378 * @try: The number of tries (must be less than 16).
379 *
380 * Compute the combined packet priority. The combined priority is dominated by
381 * the base priority, whereas the number of (re-)tries decides the precedence
382 * of packets with the same base priority, giving higher priority to packets
383 * that already have more tries.
384 *
385 * Return: Returns the computed priority as value fitting inside a &u8. A
386 * higher number means a higher priority.
387 */
388 #define SSH_PACKET_PRIORITY(base, try) \
389 __SSH_PACKET_PRIORITY(SSH_PACKET_PRIORITY_##base, (try))
390
391 /**
392 * ssh_packet_priority_get_try() - Get number of tries from packet priority.
393 * @priority: The packet priority.
394 *
395 * Return: Returns the number of tries encoded in the specified packet
396 * priority.
397 */
ssh_packet_priority_get_try(u8 priority)398 static inline u8 ssh_packet_priority_get_try(u8 priority)
399 {
400 return priority & 0x0f;
401 }
402
403 /**
404 * ssh_packet_priority_get_base - Get base priority from packet priority.
405 * @priority: The packet priority.
406 *
407 * Return: Returns the base priority encoded in the given packet priority.
408 */
ssh_packet_priority_get_base(u8 priority)409 static inline u8 ssh_packet_priority_get_base(u8 priority)
410 {
411 return (priority & 0xf0) >> 4;
412 }
413
414 enum ssh_packet_flags {
415 /* state flags */
416 SSH_PACKET_SF_LOCKED_BIT,
417 SSH_PACKET_SF_QUEUED_BIT,
418 SSH_PACKET_SF_PENDING_BIT,
419 SSH_PACKET_SF_TRANSMITTING_BIT,
420 SSH_PACKET_SF_TRANSMITTED_BIT,
421 SSH_PACKET_SF_ACKED_BIT,
422 SSH_PACKET_SF_CANCELED_BIT,
423 SSH_PACKET_SF_COMPLETED_BIT,
424
425 /* type flags */
426 SSH_PACKET_TY_FLUSH_BIT,
427 SSH_PACKET_TY_SEQUENCED_BIT,
428 SSH_PACKET_TY_BLOCKING_BIT,
429
430 /* mask for state flags */
431 SSH_PACKET_FLAGS_SF_MASK =
432 BIT(SSH_PACKET_SF_LOCKED_BIT)
433 | BIT(SSH_PACKET_SF_QUEUED_BIT)
434 | BIT(SSH_PACKET_SF_PENDING_BIT)
435 | BIT(SSH_PACKET_SF_TRANSMITTING_BIT)
436 | BIT(SSH_PACKET_SF_TRANSMITTED_BIT)
437 | BIT(SSH_PACKET_SF_ACKED_BIT)
438 | BIT(SSH_PACKET_SF_CANCELED_BIT)
439 | BIT(SSH_PACKET_SF_COMPLETED_BIT),
440
441 /* mask for type flags */
442 SSH_PACKET_FLAGS_TY_MASK =
443 BIT(SSH_PACKET_TY_FLUSH_BIT)
444 | BIT(SSH_PACKET_TY_SEQUENCED_BIT)
445 | BIT(SSH_PACKET_TY_BLOCKING_BIT),
446 };
447
448 struct ssh_ptl;
449 struct ssh_packet;
450
451 /**
452 * struct ssh_packet_ops - Callback operations for a SSH packet.
453 * @release: Function called when the packet reference count reaches zero.
454 * This callback must be relied upon to ensure that the packet has
455 * left the transport system(s).
456 * @complete: Function called when the packet is completed, either with
457 * success or failure. In case of failure, the reason for the
458 * failure is indicated by the value of the provided status code
459 * argument. This value will be zero in case of success. Note that
460 * a call to this callback does not guarantee that the packet is
461 * not in use by the transport system any more.
462 */
463 struct ssh_packet_ops {
464 void (*release)(struct ssh_packet *p);
465 void (*complete)(struct ssh_packet *p, int status);
466 };
467
468 /**
469 * struct ssh_packet - SSH transport packet.
470 * @ptl: Pointer to the packet transport layer. May be %NULL if the packet
471 * (or enclosing request) has not been submitted yet.
472 * @refcnt: Reference count of the packet.
473 * @priority: Priority of the packet. Must be computed via
474 * SSH_PACKET_PRIORITY(). Must only be accessed while holding the
475 * queue lock after first submission.
476 * @data: Raw message data.
477 * @data.len: Length of the raw message data.
478 * @data.ptr: Pointer to the raw message data buffer.
479 * @state: State and type flags describing current packet state (dynamic)
480 * and type (static). See &enum ssh_packet_flags for possible
481 * options.
482 * @timestamp: Timestamp specifying when the latest transmission of a
483 * currently pending packet has been started. May be %KTIME_MAX
484 * before or in-between transmission attempts. Used for the packet
485 * timeout implementation. Must only be accessed while holding the
486 * pending lock after first submission.
487 * @queue_node: The list node for the packet queue.
488 * @pending_node: The list node for the set of pending packets.
489 * @ops: Packet operations.
490 */
491 struct ssh_packet {
492 struct ssh_ptl *ptl;
493 struct kref refcnt;
494
495 u8 priority;
496
497 struct {
498 size_t len;
499 u8 *ptr;
500 } data;
501
502 unsigned long state;
503 ktime_t timestamp;
504
505 struct list_head queue_node;
506 struct list_head pending_node;
507
508 const struct ssh_packet_ops *ops;
509 };
510
511 struct ssh_packet *ssh_packet_get(struct ssh_packet *p);
512 void ssh_packet_put(struct ssh_packet *p);
513
514 /**
515 * ssh_packet_set_data() - Set raw message data of packet.
516 * @p: The packet for which the message data should be set.
517 * @ptr: Pointer to the memory holding the message data.
518 * @len: Length of the message data.
519 *
520 * Sets the raw message data buffer of the packet to the provided memory. The
521 * memory is not copied. Instead, the caller is responsible for management
522 * (i.e. allocation and deallocation) of the memory. The caller must ensure
523 * that the provided memory is valid and contains a valid SSH message,
524 * starting from the time of submission of the packet until the ``release``
525 * callback has been called. During this time, the memory may not be altered
526 * in any way.
527 */
ssh_packet_set_data(struct ssh_packet * p,u8 * ptr,size_t len)528 static inline void ssh_packet_set_data(struct ssh_packet *p, u8 *ptr, size_t len)
529 {
530 p->data.ptr = ptr;
531 p->data.len = len;
532 }
533
534
535 /* -- Request transport layer (rtl). ---------------------------------------- */
536
537 enum ssh_request_flags {
538 /* state flags */
539 SSH_REQUEST_SF_LOCKED_BIT,
540 SSH_REQUEST_SF_QUEUED_BIT,
541 SSH_REQUEST_SF_PENDING_BIT,
542 SSH_REQUEST_SF_TRANSMITTING_BIT,
543 SSH_REQUEST_SF_TRANSMITTED_BIT,
544 SSH_REQUEST_SF_RSPRCVD_BIT,
545 SSH_REQUEST_SF_CANCELED_BIT,
546 SSH_REQUEST_SF_COMPLETED_BIT,
547
548 /* type flags */
549 SSH_REQUEST_TY_FLUSH_BIT,
550 SSH_REQUEST_TY_HAS_RESPONSE_BIT,
551
552 /* mask for state flags */
553 SSH_REQUEST_FLAGS_SF_MASK =
554 BIT(SSH_REQUEST_SF_LOCKED_BIT)
555 | BIT(SSH_REQUEST_SF_QUEUED_BIT)
556 | BIT(SSH_REQUEST_SF_PENDING_BIT)
557 | BIT(SSH_REQUEST_SF_TRANSMITTING_BIT)
558 | BIT(SSH_REQUEST_SF_TRANSMITTED_BIT)
559 | BIT(SSH_REQUEST_SF_RSPRCVD_BIT)
560 | BIT(SSH_REQUEST_SF_CANCELED_BIT)
561 | BIT(SSH_REQUEST_SF_COMPLETED_BIT),
562
563 /* mask for type flags */
564 SSH_REQUEST_FLAGS_TY_MASK =
565 BIT(SSH_REQUEST_TY_FLUSH_BIT)
566 | BIT(SSH_REQUEST_TY_HAS_RESPONSE_BIT),
567 };
568
569 struct ssh_rtl;
570 struct ssh_request;
571
572 /**
573 * struct ssh_request_ops - Callback operations for a SSH request.
574 * @release: Function called when the request's reference count reaches zero.
575 * This callback must be relied upon to ensure that the request has
576 * left the transport systems (both, packet an request systems).
577 * @complete: Function called when the request is completed, either with
578 * success or failure. The command data for the request response
579 * is provided via the &struct ssh_command parameter (``cmd``),
580 * the command payload of the request response via the &struct
581 * ssh_span parameter (``data``).
582 *
583 * If the request does not have any response or has not been
584 * completed with success, both ``cmd`` and ``data`` parameters will
585 * be NULL. If the request response does not have any command
586 * payload, the ``data`` span will be an empty (zero-length) span.
587 *
588 * In case of failure, the reason for the failure is indicated by
589 * the value of the provided status code argument (``status``). This
590 * value will be zero in case of success and a regular errno
591 * otherwise.
592 *
593 * Note that a call to this callback does not guarantee that the
594 * request is not in use by the transport systems any more.
595 */
596 struct ssh_request_ops {
597 void (*release)(struct ssh_request *rqst);
598 void (*complete)(struct ssh_request *rqst,
599 const struct ssh_command *cmd,
600 const struct ssam_span *data, int status);
601 };
602
603 /**
604 * struct ssh_request - SSH transport request.
605 * @packet: The underlying SSH transport packet.
606 * @node: List node for the request queue and pending set.
607 * @state: State and type flags describing current request state (dynamic)
608 * and type (static). See &enum ssh_request_flags for possible
609 * options.
610 * @timestamp: Timestamp specifying when we start waiting on the response of
611 * the request. This is set once the underlying packet has been
612 * completed and may be %KTIME_MAX before that, or when the request
613 * does not expect a response. Used for the request timeout
614 * implementation.
615 * @ops: Request Operations.
616 */
617 struct ssh_request {
618 struct ssh_packet packet;
619 struct list_head node;
620
621 unsigned long state;
622 ktime_t timestamp;
623
624 const struct ssh_request_ops *ops;
625 };
626
627 /**
628 * to_ssh_request() - Cast a SSH packet to its enclosing SSH request.
629 * @p: The packet to cast.
630 *
631 * Casts the given &struct ssh_packet to its enclosing &struct ssh_request.
632 * The caller is responsible for making sure that the packet is actually
633 * wrapped in a &struct ssh_request.
634 *
635 * Return: Returns the &struct ssh_request wrapping the provided packet.
636 */
to_ssh_request(struct ssh_packet * p)637 static inline struct ssh_request *to_ssh_request(struct ssh_packet *p)
638 {
639 return container_of(p, struct ssh_request, packet);
640 }
641
642 /**
643 * ssh_request_get() - Increment reference count of request.
644 * @r: The request to increment the reference count of.
645 *
646 * Increments the reference count of the given request by incrementing the
647 * reference count of the underlying &struct ssh_packet, enclosed in it.
648 *
649 * See also ssh_request_put(), ssh_packet_get().
650 *
651 * Return: Returns the request provided as input.
652 */
ssh_request_get(struct ssh_request * r)653 static inline struct ssh_request *ssh_request_get(struct ssh_request *r)
654 {
655 return r ? to_ssh_request(ssh_packet_get(&r->packet)) : NULL;
656 }
657
658 /**
659 * ssh_request_put() - Decrement reference count of request.
660 * @r: The request to decrement the reference count of.
661 *
662 * Decrements the reference count of the given request by decrementing the
663 * reference count of the underlying &struct ssh_packet, enclosed in it. If
664 * the reference count reaches zero, the ``release`` callback specified in the
665 * request's &struct ssh_request_ops, i.e. ``r->ops->release``, will be
666 * called.
667 *
668 * See also ssh_request_get(), ssh_packet_put().
669 */
ssh_request_put(struct ssh_request * r)670 static inline void ssh_request_put(struct ssh_request *r)
671 {
672 if (r)
673 ssh_packet_put(&r->packet);
674 }
675
676 /**
677 * ssh_request_set_data() - Set raw message data of request.
678 * @r: The request for which the message data should be set.
679 * @ptr: Pointer to the memory holding the message data.
680 * @len: Length of the message data.
681 *
682 * Sets the raw message data buffer of the underlying packet to the specified
683 * buffer. Does not copy the actual message data, just sets the buffer pointer
684 * and length. Refer to ssh_packet_set_data() for more details.
685 */
ssh_request_set_data(struct ssh_request * r,u8 * ptr,size_t len)686 static inline void ssh_request_set_data(struct ssh_request *r, u8 *ptr, size_t len)
687 {
688 ssh_packet_set_data(&r->packet, ptr, len);
689 }
690
691 #endif /* _LINUX_SURFACE_AGGREGATOR_SERIAL_HUB_H */
692