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5 .Dd July 9, 2018
6 .Dt IEC61883 7I
7 .Os
8 .Sh NAME
9 .Nm iec61883
10 .Nd IEC 61883 interfaces
11 .Sh SYNOPSIS
12 .In sys/av/iec61883.h
13 .Sh DESCRIPTION
14 The set of interfaces described in this man page can be used to control and
15 exchange data with consumer audio/video devices using protocols specified
16 in
17 .%T "IIEC 61883 Consumer Electronic Audio/Video Equipment - Digital Interface"
18 including Common Isochronous Packet (CIP), Connection Management
19 Procedures (CMP) and Function Control Protocol (FCP).
20 .Pp
21 An
22 .Nm
23 compliant driver exports two device nodes for isochronous and
24 for asynchronous transactions.
25 See the
26 .Sx FILES
27 section of this man page for the namespace definition.
28 .Ss "Isochronous Transfers"
29 Two methods are provided to receive/transmit isochronous data: using
30 .Xr mmap 2
31 in combination with
32 .Xr ioctl 2 ,
33 and
34 .Xr read 2
35 or
36 .Xr write 2 .
37 .Ss "Mmap/Ioctl"
38 This method provides better performance and finer-grained control than
39 read/write, and is a method of choice for most applications.
40 The data buffer is
41 mapped into a user process address space, which means no data copying between
42 the kernel and an application is necessary.
43 Synchronization between user
44 processes and the driver is performed using
45 .Xr ioctl 2
46 commands.
47 .Pp
48 An application allocates resources for isochronous transfer using
49 .Dv IEC61883_ISOCH_INIT .
50 Then the data buffer can be mapped into the process
51 space using
52 .Xr mmap 2 .
53 .Pp
54 A circular data buffer consists of one or more equal size frame buffers
55 (further referred to as frames, unless to avoid ambiguity with AV frames).
56 Frames are numbered starting with zero and are always transferred sequentially.
57 Frames consist equal sized packets.
58 Each packet contains a CIP header and one or more data blocks.
59 .Pp
60 A driver and an application act as a producer and a consumer: producer supplies
61 .Em full
62 frames (filled with data) to the consumer, and the producer is not
63 allowed to access those frames until the consumer claims them
64 .Em empty .
65 .Pp
66 A transfer can be initiated and suspended with
67 .Dv IEC61883_START
68 and
69 .Dv IEC61883_STOP
70 commands respectively.
71 .Dv IEC61883_RECV
72 or
73 .Dv IEC61883_XMIT
74 is used for producer-consumer synchronization.
75 .Ss "Read/Write"
76 Using this method, an application calls
77 .Xr read 2
78 or
79 .Xr write 2
80 to receive or transmit a specified amount of data.
81 Bus-specific overhead, such as isochronous packet headers, is handled by the driver
82 and is not exposed to applications.
83 Data returned by
84 .Xr read 2
85 contains CIP headers and data blocks.
86 Empty packets are not returned by
87 .Xr read 2 .
88 .Xr write 2
89 data should meet the same requirements.
90 .Pp
91 If one or more channels have been allocated since
92 .Xr open 2
93 (see
94 .Dv IEC61883_ISOCH_INIT ) ,
95 the data is received/transmitted using channel that was created the last.
96 .Pp
97 If no channels were allocated, the driver uses the broadcast channel by default
98 and allocates the default-size data buffer.
99 During transmit, the first packet's CIP header is used to auto-detect the data format.
100 If it is one of the formats supported by the driver, it is properly transmitted (with
101 inserted empty packets and timestamps).
102 .Pp
103 For both methods, if during transmit the driver runs out of data, it transmits
104 empty packets containing only a CIP header of the next to be transmitted
105 packet, as defined in
106 .Em IEC 61883-1 .
107 .Ss "Connection Management Procedures"
108 Applications wishing to follow Connection Management Procedures (CMP) in
109 combination with isochronous transfers should use the
110 .Xr ioctl 2
111 .Dv IEC61883_PLUG_INIT ,
112 .Dv IEC61883_PLUG_FINI ,
113 .Dv IEC61883_PLUG_REG_READ
114 and
115 .Dv IEC61883_PLUG_REG_CAS
116 commands.
117 .Ss "Asynchronous Transactions"
118 .Xr read 2 ,
119 .Xr write 2 ,
120 .Xr ioctl 2 ,
121 and
122 .Xr poll 2
123 can be used
124 with asynchronous nodes.
125 Asynchronous data exchange between a driver and an
126 application utilizes a common data structure called asynchronous request (ARQ):
127 .Bd -literal -offset 2n
128 typedef struct iec61883_arq {
129 int arq_type;
130 int arq_len;
131 union {
132 uint32_t quadlet;
133 uint64_t octlet;
134 uint8_t buf[8];
135 } arq_data;
136 } iec61883_arq_t;
137 .Ed
138 .Pp
139 .Fa arq_type
140 contains
141 .Sy ARQ
142 type:
143 .Pp
144 .Bl -tag -width " " -compact
145 .It Dv IEC61883_ARQ_FCP_CMD
146 .It Dv IEC61883_ARQ_FCP_RESP
147 .Pp
148 .Sy FCP
149 command and response frame respectively.
150 Outgoing frames are sent using
151 .Xr write 2 ,
152 incoming frames are received with
153 .Xr read 2 .
154 .Pp
155 See
156 .Em IIEC 61883-1
157 for the FCP frame structure definition.
158 .Pp
159 .It Dv IEC61883_ARQ_BUS_RESET
160 .Pp
161 Returned by the driver when a bus reset occurs.
162 There is no data associated with this request type, and \fBarq_len\fR is set to 0.
163 .El
164 .Pp
165 If
166 .Fa arq_len
167 is 4 or 8, then data should be supplied in
168 .Fa arq_data.quadlet
169 or
170 .Fa arq_data.octlet
171 respectively, otherwise up to 8 bytes can be put in
172 .Fa arq_data.buf ,
173 with the rest of the data following immediately after.
174 .Ss "write(2)"
175 For a request to be sent to a target, an
176 .Vt iec61883_arq_t
177 structure along with associated data is passed to the driver using
178 .Xr write 2 .
179 .Xr write 2
180 blocks until the request is completed.
181 .Ss "read(2)"
182 A driver collects incoming ARQs in the internal buffer.
183 Buffer size can be changed using the
184 .Xr ioctl 2
185 command
186 .Vt IEC61883_FCP_SET_IBUF_SIZE .
187 .Pp
188 Reading an ARQ takes one or two steps depending on data length.
189 An application
190 first reads
191 .Ql sizeof (iec61883_arq_t)
192 bytes: if
193 .Fa arq_len
194 is less than or equal 4, which is usually the case, no additional step is needed.
195 Otherwise,
196 the remaining
197 .Ql arq_len - 4
198 bytes should be read and concatenated.
199 .Pp
200 .Xr read 2
201 blocks until the specified amount of data is available, unless
202 .Dv O_NONBLOCK
203 or
204 .Dv O_NDELAY
205 flag was set during
206 .Xr open 2 ,
207 in which case
208 .Xr read 2
209 returns immediately.
210 .Ss "poll(2)"
211 Applications can
212 .Xr poll 2
213 asynchronous nodes on the
214 .Dv POLLIN
215 event.
216 .Ss "Bus Reset"
217 In case of a bus reset, the driver notifies an application by generating an
218 .Sy ARQ
219 of type
220 .Dv IEC61883_ARQ_BUS_RESET .
221 .Pp
222 If there were established isochronous connections before bus reset, the driver
223 attempts to restore all connections as described in
224 .Em IEC 61883
225 and resume any active transfers that were in progress.
226 .Sh IOCTLS
227 The following commands only apply to isochronous nodes:
228 .Bl -tag -width " "
229 .It Dv IEC61883_ISOCH_INIT
230 .Pp
231 This command allocates a data buffer and isochronous resources (if necessary)
232 for the isochronous transfer.
233 The argument is a pointer to the structure:
234 .Bd -literal -offset 2n
235 typedef struct iec61883_isoch_init {
236 int ii_version; /* interface version */
237 int ii_pkt_size; /* packet size */
238 int ii_frame_size; /* packets/frame */
239 int ii_frame_cnt; /* # of frames */
240 int ii_direction; /* xfer direction */
241 int ii_bus_speed; /* bus speed */
242 uint64_t ii_channel; /* channel mask */
243 int ii_dbs; /* DBS */
244 int ii_fn; /* FN */
245 int ii_rate_n; /* rate numerator */
246 int ii_rate_d; /* rate denominator */
247 int ii_ts_mode; /* timestamp mode */
248 int ii_flags; /* flags */
249 int ii_handle; /* isoch handle */
250 int ii_frame_rcnt; /* # of frames */
251 off_t *ii_mmap_off /* mmap offset */
252 int ii_rchannel; /* channel */
253 int ii_error; /* error code */
254 } iec61883_isoch_init_t;
255 .Ed
256 .Pp
257 .Fa ii_version
258 should be set to
259 .Dv IEC61883_V1_0 .
260 .Pp
261 The driver attempts to allocate a data buffer consisting of
262 .Fa ii_frame_cnt
263 frames, with
264 .Fa ii_frame_size
265 packets in each frame.
266 Packet size in bytes is specified by
267 .Fa ii_pkt_size
268 specifies and should be a multiple of 512 and compatible with
269 .Fa ii_bus_speed .
270 .Pp
271 .Fa ii_direction
272 can take one of the following values:
273 .Bl -tag -width "IEC61883_DIR_RECV"
274 .It Dv IEC61883_DIR_RECV
275 Receiving isochronous data.
276 .It Dv IEC61883_DIR_XMIT
277 Transmitting isochronous data.
278 .El
279 .Pp
280 .Fa ii_bus_speed
281 chooses bus speed to be used and can be either
282 .Dv IEC61883_S100 ,
283 .Dv IEC61883_S200
284 or
285 .Dv IEC61883_S400 .
286 .Pp
287 .Fa ii_channel
288 is a mask that specifies an isochronous channel number to be
289 used, with the
290 .Em N Ns th
291 bit representing channel
292 .Em N .
293 When transmitting data, several bits can be set at a time, in which case the
294 driver chooses one, for example,
295 .Sy 0x3FF
296 means a range from 0 to 9.
297 In case of receive, only one bit can be set.
298 .Pp
299 .Fa ii_dbs
300 specifies data block size in quadlets, for example, DBS value for
301 .Dv SD-DVCR
302 is
303 .Sy 0x78 .
304 Refer to
305 .Em IEC 61883
306 for more details on DBS.
307 .Pp
308 .Fa ii_fn
309 specifies fraction number, which defines the number of blocks in which a
310 source packet is divided.
311 Allowed values are from 0 to 3.
312 Refer to
313 .Em IEC 61883
314 for more details on FN.
315 .Pp
316 Data rate expected by the AV device can be lower than the bus speed, in which
317 case the driver has to periodically insert empty packets into the data stream
318 to avoid device buffer overflows.
319 This rate is specified with a fraction N/D,
320 set by
321 .Fa ii_rate_n
322 and
323 .Fa ii_rate_d
324 respectively.
325 Any integer numbers can be used, or the following predefined constants:
326 .Pp
327 .Bl -tag -width "IEC61883_RATE_N_DV_NTSC" -compact
328 .It Dv IEC61883_RATE_N_DV_NTSC
329 .It Dv IEC61883_RATE_D_DV_NTSC
330 Data rate expected by
331 .Sy DV-NTSC
332 devices.
333 .Pp
334 .It Dv IEC61883_RATE_N_DV_PAL
335 .It Dv IEC61883_RATE_D_DV_PAL
336 Data rate expected by
337 .Sy DV-PAL
338 devices.
339 .El
340 .Pp
341 During data transmission, a timestamp based on the current value of the cycle
342 timer is usually required.
343 .Fa ii_ts_mode
344 defines timestamp mode to be used:
345 .Bl -tag -width IEC61883_TS_NONE
346 .It Dv IEC61883_TS_SYT
347 Driver puts a timestamp in the SYT field of the first CIP header of each frame.
348 .It Dv IEC61883_TS_NONE
349 No timestamps.
350 .El
351 .Pp
352 .Fa ii_dbs ,
353 .Fa ii_fn ,
354 .Fa ii_rate_n ,
355 .Fa ii_rate_d
356 and
357 .Fa ii_ts_mode
358 are only required for transmission.
359 In other case these should be set to 0.
360 .Pp
361 .Fa ii_flags
362 should be set to 0.
363 .Pp
364 If command succeeds,
365 .Fa ii_handle
366 contains a handle that should be used with other isochronous commands.
367 .Fa ii_frame_rcnt
368 contains the number of allocated frames (can be less than
369 .Fa ii_frame_cnt ) .
370 .Fa ii_mmap_off
371 contains an offset to be used in
372 .Xr mmap 2 ,
373 for example, to map an entire data receive buffer:
374 .Bd -literal -offset 2n
375 pa = mmap(NULL, init.ii_pkt_size *
376 init.ii_frame_size * init.ii_frame_rcnt,
377 PROT_READ, MAP_PRIVATE, fd, init.ii_mmap_off);
378 .Ed
379 .Pp
380 .Fa ii_rchannel
381 contains channel number.
382 .Pp
383 In case of command success,
384 .Fa ii_error
385 is set to 0; otherwise one of the following values can be returned:
386 .Bl -tag -width IEC61883_ERR_NOCHANNEL
387 .It Dv IEC61883_ERR_NOMEM
388 Not enough memory for the data buffer.
389 .It Dv IEC61883_ERR_NOCHANNEL
390 Cannot allocate isochronous channel.
391 .It Dv IEC61883_ERR_PKT_SIZE
392 Packet size is not allowed at this bus speed.
393 .It Dv IEC61883_ERR_VERSION
394 Interface version is not supported.
395 .It Dv IEC61883_ERR_INVAL
396 One or more the parameters are invalid
397 .It Dv IEC61883_ERR_OTHER
398 Unspecified error type.
399 .El
400 .It Dv IEC61883_ISOCH_FINI
401 .Pp
402 Argument is a handle returned by
403 .Dv IEC61883_ISOCH_INIT .
404 This command frees any resources associated with this handle.
405 There must be no active transfers
406 and the data buffer must be unmapped; otherwise the command fails.
407 .It Dv IEC61883_START
408 .Pp
409 This command starts an isochronous transfer.
410 The argument is a handle returned
411 by
412 .Dv IEC61883_ISOCH_INIT .
413 .It Dv IEC61883_STOP
414 .Pp
415 This command stops an isochronous transfer.
416 The argument is a handle returned by
417 .Dv IEC61883_ISOCH_INIT .
418 .It Dv IEC61883_RECV
419 .Pp
420 This command is used to receive full frames and return empty frames to the driver.
421 The argument is a pointer to the structure:
422 .Bd -literal -offset 2n
423 typedef struct iec61883_recv {
424 int rx_handle; /* isoch handle */
425 int rx_flags; /* flags */
426 iec61883_xfer_t rx_xfer; /* xfer params */
427 } iec61883_recv_t;
428
429 typedef struct iec61883_xfer {
430 int xf_empty_idx; /* first empty frame */
431 int xf_empty_cnt; /* empty frame count */
432 int xf_full_idx; /* first full frame */
433 int xf_full_cnt; /* full frame count */
434 int xf_error; /* error */
435 } iec61883_xfer_t;
436 .Ed
437 .Pp
438 .Fa rx_flags
439 should be set to 0.
440 .Pp
441 An application sets
442 .Fa xf_empty_idx
443 and
444 .Fa xf_empty_cnt
445 to indicate frames it no longer needs.
446 E. g. if a buffer consists of 6 frames,
447 .Fa xf_empty_idx
448 is 4,
449 .Fa xf_empty_cnt
450 is 3 - means that frames 4, 5 and 0 can now be reused by the driver.
451 If there are no empty frames, for example, the
452 first time this command is called,
453 .Fa xf_empty_cnt
454 should be set to 0.
455 .Pp
456 When the command returns,
457 .Fa xf_full_idx
458 and
459 .Fa xf_full_cnt
460 specifies the frames that are full.
461 .Fa xf_error
462 is always 0.
463 .Pp
464 In general, AV frame boundaries are not aligned with the frame buffer
465 boundaries, because the first received packet might not be the first packet of
466 an AV frame, and, in contrast with the read/write method, the driver does not
467 remove empty CIP packets.
468 .Pp
469 Applications should detect empty packets by comparing adjacent packets'
470 continuity counters (DBC field of the CIP header).
471 .It Dv IEC61883_XMIT
472 .Pp
473 This command is used to transmit full frames and get more empty frames from the
474 driver.
475 The argument is a pointer to the structure:
476 .Bd -literal -offset 2n
477 typedef struct iec61883_xmit {
478 int tx_handle; /* isoch handle */
479 int tx_flags; /* flags */
480 iec61883_xfer_t tx_xfer; /* xfer params */
481 int tx_miss_cnt; /* missed cycles */
482 } iec61883_xmit_t;
483 .Ed
484 .Pp
485 .Fa tx_flags
486 should be set to zero.
487 .Pp
488 The application sets
489 .Fa xf_full_idx
490 and
491 .Fa xf_full_cnt
492 to specify frames it wishes to transmit.
493 If there are no frames to transmit (e. g. the first time this command is called),
494 .Fa xf_full_cnt
495 should be set to 0.
496 .Pp
497 When the command returns,
498 .Fa xf_empty_idx
499 and
500 .Fa xf_empty_cnt
501 specifies empty frames which can be to transmit more data.
502 .Fa xf_error
503 is always 0.
504 .Pp
505 .Fa tx_miss_cnt
506 contains the number of isochronous cycles missed since last
507 transfer due to data buffer under run.
508 This can happen when an application does not supply data fast enough.
509 For the purposes of time stamping, the driver considers the first packet in a
510 frame buffer to be the first packet of an AV frame.
511 .It Dv IEC61883_PLUG_INIT
512 .Pp
513 This command returns a handle for the specified plug.
514 The argument is a pointer
515 to the structure:
516 .Bd -literal -offset 2n
517 typedef struct iec61883_plug_init {
518 int pi_ver; /* interface version */
519 int pi_loc; /* plug location */
520 int pi_type; /* plug type */
521 int pi_num; /* plug number */
522 int pi_flags; /* flags */
523 int pi_handle; /* plug handle */
524 int pi_rnum; /* plug number */
525 } iec61883_plug_init_t;
526 .Ed
527 .Pp
528 .Fa pi_ver
529 should be set to
530 .Dv IEC61883_V1_0 .
531 .Pp
532 .Fa pi_loc
533 specifies plug location:
534 .Bl -tag -width IEC61883_LOC_REMOTE
535 .It Dv IEC61883_LOC_LOCAL
536 On the local unit (local plug).
537 A plug control register (PCR) is allocated.
538 Command fails if the plug already exists
539 .It Dv IEC61883_LOC_REMOTE
540 On the remote unit (remote plug).
541 The plug should exist on the remote unit,
542 otherwise the command fails.
543 .El
544 .Pp
545 .Fa pi_type
546 specifies isochronous plug type:
547 .Pp
548 .Bl -tag -width " " -compact
549 .It Dv IEC61883_PLUG_IN
550 .It Dv IEC61883_PLUG_OUT
551 .Pp
552 Input or output plugs.
553 .Pp
554 .It Dv IEC61883_PLUG_MASTER_IN
555 .It Dv IEC61883_PLUG_MASTER_OUT
556 .Pp
557 Master input or master output plug.
558 These plugs always exist on the local unit.
559 .El
560 .Pp
561 .Fa pi_num
562 specifies plug number.
563 This should be 0 for master plugs, and from 0 to 31 for input/output plugs.
564 Alternatively, a special value
565 .Dv IEC61883_PLUG_ANY
566 can be used to let the driver choose a free plug
567 number, create the plug and return the number in
568 .Fa pi_rnum .
569 .Pp
570 .Fa pi_flags
571 should be set to 0.
572 .Pp
573 If the command succeeds,
574 .Fa pi_handle
575 contains a handle that should be used with other plug commands.
576 .It Dv IEC61883_PLUG_FINI
577 .Pp
578 Argument is a handle returned by
579 .Dv IEC61883_PLUG_INIT .
580 This command frees any resources associated with this handle, including the PCR.
581 .It Dv IEC61883_PLUG_REG_READ
582 .Pp
583 Read plug register value.
584 The argument is a pointer to the structure:
585 .Bd -literal -offset 2n
586 typedef struct iec61883_plug_reg_val {
587 int pr_handle; /* plug handle */
588 uint32_t pr_val; /* register value */
589 } iec61883_plug_reg_val_t;
590 .Ed
591 .Pp
592 .Fa pr_handle
593 is a handle returned by
594 .Dv IEC61883_PLUG_INIT .
595 Register
596 value is returned in
597 .Fa pr_val .
598 .It Dv IEC61883_PLUG_REG_CAS
599 .Pp
600 Atomically compare and swap plug register value.
601 The argument is a pointer to the structure:
602 .Bd -literal -offset 2n
603 typedef struct iec61883_plug_reg_lock {
604 int pl_handle; /* plug handle */
605 uint32_t pl_arg; /* compare arg */
606 uint32_t pl_data; /* write value */
607 UINT32_t pl_old; /* original value */
608 } iec61883_plug_reg_lock_t;
609 .Ed
610 .Pp
611 .Fa pr_handle
612 is a handle returned by IEC61883_PLUG_INIT.
613 .Pp
614 Original register value is compared with
615 .Fa pl_arg
616 and if they are equal, register value is replaced with
617 .Fa pl_data .
618 In any case, the original value is stored in
619 .Fa pl_old .
620 .El
621 .Pp
622 The following commands only apply to asynchronous nodes:
623 .Bl -tag -width " "
624 .It Dv IEC61883_ARQ_GET_IBUF_SIZE
625 .Pp
626 This command returns current incoming ARQ buffer size.
627 The argument is a
628 pointer to
629 .Vt int .
630 .It Dv IEC61883_ARQ_SET_IBUF_SIZE
631 .Pp
632 This command changes incoming ARQ buffer size.
633 The argument is the new buffer
634 size in bytes.
635 .El
636 .Sh FILES
637 .Bl -tag -width /dev/av/N/async
638 .It Pa /dev/av/N/async
639 Device node for asynchronous data
640 .It Pa /dev/av/N/isoch
641 Device has been disconnected
642 .El
643 .Sh ERRORS
644 .Bl -tag -width EFAULT
645 .It Er EIO
646 Bus operation failed.
647 DMA failure.
648 .It Er EFAULT
649 .Xr ioctl 2
650 argument points to an illegal address.
651 .It Er EINVAL
652 Invalid argument or argument combination.
653 .It Er ENODEV
654 Device has been disconnected.
655 .El
656 .Sh ARCHITECTURE
657 All
658 .Sh INTERFACE STABILITY
659 Committed
660 .Sh SEE ALSO
661 .Xr ioctl 2 ,
662 .Xr mmap 2 ,
663 .Xr open 2 ,
664 .Xr poll 2 ,
665 .Xr read 2 ,
666 .Xr write 2 ,
667 .Xr attributes 5 ,
668 .Xr av1394 7D
669 .Rs
670 .%B IIEC 61883 Consumer audio/video equipment - Digital interface
671 .Re
672 .Rs
673 .%B IEEE Std 1394-1995 Standard for a High Performance Serial Bus
674 .Re