path: root/usr/src/man/man4i/iec61883.4i

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.Dd July  9, 2018
.Dt IEC61883 4I
.Os
.Sh NAME
.Nm iec61883
.Nd IEC 61883 interfaces
.Sh SYNOPSIS
.In sys/av/iec61883.h
.Sh DESCRIPTION
The set of interfaces described in this man page can be used to control and
exchange data with consumer audio/video devices using protocols specified
in
.%T "IIEC 61883 Consumer Electronic Audio/Video Equipment - Digital Interface"
including Common Isochronous Packet (CIP), Connection Management
Procedures (CMP) and Function Control Protocol (FCP).
.Pp
An
.Nm
compliant driver exports two device nodes for isochronous and
for asynchronous transactions.
See the
.Sx FILES
section of this man page for the namespace definition.
.Ss "Isochronous Transfers"
Two methods are provided to receive/transmit isochronous data: using
.Xr mmap 2
in combination with
.Xr ioctl 2 ,
and
.Xr read 2
or
.Xr write 2 .
.Ss "Mmap/Ioctl"
This method provides better performance and finer-grained control than
read/write, and is a method of choice for most applications.
The data buffer is
mapped into a user process address space, which means no data copying between
the kernel and an application is necessary.
Synchronization between user
processes and the driver is performed using
.Xr ioctl 2
commands.
.Pp
An application allocates resources for isochronous transfer using
.Dv IEC61883_ISOCH_INIT .
Then the data buffer can be mapped into the process
space using
.Xr mmap 2 .
.Pp
A circular data buffer consists of one or more equal size frame buffers
(further referred to as frames, unless to avoid ambiguity with AV frames).
Frames are numbered starting with zero and are always transferred sequentially.
Frames consist equal sized packets.
Each packet contains a CIP header and one or more data blocks.
.Pp
A driver and an application act as a producer and a consumer: producer supplies
.Em full
frames (filled with data) to the consumer, and the producer is not
allowed to access those frames until the consumer claims them
.Em empty .
.Pp
A transfer can be initiated and suspended with
.Dv IEC61883_START
and
.Dv IEC61883_STOP
commands respectively.
.Dv IEC61883_RECV
or
.Dv IEC61883_XMIT
is used for producer-consumer synchronization.
.Ss "Read/Write"
Using this method, an application calls
.Xr read 2
or
.Xr write 2
to receive or transmit a specified amount of data.
Bus-specific overhead, such as isochronous packet headers, is handled by the driver
and is not exposed to applications.
Data returned by
.Xr read 2
contains CIP headers and data blocks.
Empty packets are not returned by
.Xr read 2 .
.Xr write 2
data should meet the same requirements.
.Pp
If one or more channels have been allocated since
.Xr open 2
(see
.Dv IEC61883_ISOCH_INIT ) ,
the data is received/transmitted using channel that was created the last.
.Pp
If no channels were allocated, the driver uses the broadcast channel by default
and allocates the default-size data buffer.
During transmit, the first packet's CIP header is used to auto-detect the data format.
If it is one of the formats supported by the driver, it is properly transmitted (with
inserted empty packets and timestamps).
.Pp
For both methods, if during transmit the driver runs out of data, it transmits
empty packets containing only a CIP header of the next to be transmitted
packet, as defined in
.Em IEC 61883-1 .
.Ss "Connection Management Procedures"
Applications wishing to follow Connection Management Procedures (CMP) in
combination with isochronous transfers should use the
.Xr ioctl 2
.Dv IEC61883_PLUG_INIT ,
.Dv IEC61883_PLUG_FINI ,
.Dv IEC61883_PLUG_REG_READ
and
.Dv IEC61883_PLUG_REG_CAS
commands.
.Ss "Asynchronous Transactions"
.Xr read 2 ,
.Xr write 2 ,
.Xr ioctl 2 ,
and
.Xr poll 2
can be used
with asynchronous nodes.
Asynchronous data exchange between a driver and an
application utilizes a common data structure called asynchronous request (ARQ):
.Bd -literal -offset 2n
typedef struct iec61883_arq {
        int        arq_type;
        int        arq_len;
        union {
                uint32_t   quadlet;
                uint64_t   octlet;
                uint8_t    buf[8];
        } arq_data;
} iec61883_arq_t;
.Ed
.Pp
.Fa arq_type
contains
.Sy ARQ
type:
.Pp
.Bl -tag -width " " -compact
.It Dv IEC61883_ARQ_FCP_CMD
.It Dv IEC61883_ARQ_FCP_RESP
.Pp
.Sy FCP
command and response frame respectively.
Outgoing frames are sent using
.Xr write 2 ,
incoming frames are received with
.Xr read 2 .
.Pp
See
.Em IIEC 61883-1
for the FCP frame structure definition.
.Pp
.It Dv IEC61883_ARQ_BUS_RESET
.Pp
Returned by the driver when a bus reset occurs.
There is no data associated with this request type, and \fBarq_len\fR is set to 0.
.El
.Pp
If
.Fa arq_len
is 4 or 8, then data should be supplied in
.Fa arq_data.quadlet
or
.Fa arq_data.octlet
respectively, otherwise up to 8 bytes can be put in
.Fa arq_data.buf ,
with the rest of the data following immediately after.
.Ss "write(2)"
For a request to be sent to a target, an
.Vt iec61883_arq_t
structure along with associated data is passed to the driver using
.Xr write 2 .
.Xr write 2
blocks until the request is completed.
.Ss "read(2)"
A driver collects incoming ARQs in the internal buffer.
Buffer size can be changed using the
.Xr ioctl 2
command
.Vt IEC61883_FCP_SET_IBUF_SIZE .
.Pp
Reading an ARQ takes one or two steps depending on data length.
An application
first reads
.Ql sizeof (iec61883_arq_t)
bytes: if
.Fa arq_len
is less than or equal 4, which is usually the case, no additional step is needed.
Otherwise,
the remaining
.Ql arq_len - 4
bytes should be read and concatenated.
.Pp
.Xr read 2
blocks until the specified amount of data is available, unless
.Dv O_NONBLOCK
or
.Dv O_NDELAY
flag was set during
.Xr open 2 ,
in which case
.Xr read 2
returns immediately.
.Ss "poll(2)"
Applications can
.Xr poll 2
asynchronous nodes on the
.Dv POLLIN
event.
.Ss "Bus Reset"
In case of a bus reset, the driver notifies an application by generating an
.Sy ARQ
of type
.Dv IEC61883_ARQ_BUS_RESET .
.Pp
If there were established isochronous connections before bus reset, the driver
attempts to restore all connections as described in
.Em IEC 61883
and resume any active transfers that were in progress.
.Sh IOCTLS
The following commands only apply to isochronous nodes:
.Bl -tag -width " "
.It Dv IEC61883_ISOCH_INIT
.Pp
This command allocates a data buffer and isochronous resources (if necessary)
for the isochronous transfer.
The argument is a pointer to the structure:
.Bd -literal -offset 2n
typedef struct iec61883_isoch_init {
      int   ii_version;     /* interface version */
      int   ii_pkt_size;    /* packet size */
      int   ii_frame_size;  /* packets/frame */
      int   ii_frame_cnt;   /* # of frames */
      int   ii_direction;   /* xfer direction */
      int   ii_bus_speed;   /* bus speed */
      uint64_t ii_channel;  /* channel mask */
      int   ii_dbs;         /* DBS */
      int   ii_fn;          /* FN */
      int   ii_rate_n;      /* rate numerator */
      int   ii_rate_d;      /* rate denominator */
      int   ii_ts_mode;     /* timestamp mode */
      int   ii_flags;       /* flags */
      int   ii_handle;      /* isoch handle */
      int   ii_frame_rcnt;  /* # of frames */
      off_t *ii_mmap_off    /* mmap offset */
      int   ii_rchannel;    /* channel */
      int   ii_error;       /* error code */
} iec61883_isoch_init_t;
.Ed
.Pp
.Fa ii_version
should be set to
.Dv IEC61883_V1_0 .
.Pp
The driver attempts to allocate a data buffer consisting of
.Fa ii_frame_cnt
frames, with
.Fa ii_frame_size
packets in each frame.
Packet size in bytes is specified by
.Fa ii_pkt_size
specifies and should be a multiple of 512 and compatible with
.Fa ii_bus_speed .
.Pp
.Fa ii_direction
can take one of the following values:
.Bl -tag -width "IEC61883_DIR_RECV"
.It Dv IEC61883_DIR_RECV
Receiving isochronous data.
.It Dv IEC61883_DIR_XMIT
Transmitting isochronous data.
.El
.Pp
.Fa ii_bus_speed
chooses bus speed to be used and can be either
.Dv IEC61883_S100 ,
.Dv IEC61883_S200
or
.Dv IEC61883_S400 .
.Pp
.Fa ii_channel
is a mask that specifies an isochronous channel number to be
used, with the
.Em N Ns th
bit representing channel
.Em N .
When transmitting data, several bits can be set at a time, in which case the
driver chooses one, for example,
.Sy 0x3FF
means a range from 0 to 9.
In case of receive, only one bit can be set.
.Pp
.Fa ii_dbs
specifies data block size in quadlets, for example, DBS value for
.Dv SD-DVCR
is
.Sy 0x78 .
Refer to
.Em IEC 61883
for more details on DBS.
.Pp
.Fa ii_fn
specifies fraction number, which defines the number of blocks in which a
source packet is divided.
Allowed values are from 0 to 3.
Refer to
.Em IEC 61883
for more details on FN.
.Pp
Data rate expected by the AV device can be lower than the bus speed, in which
case the driver has to periodically insert empty packets into the data stream
to avoid device buffer overflows.
This rate is specified with a fraction N/D,
set by
.Fa ii_rate_n
and
.Fa ii_rate_d
respectively.
Any integer numbers can be used, or the following predefined constants:
.Pp
.Bl -tag -width "IEC61883_RATE_N_DV_NTSC" -compact
.It Dv IEC61883_RATE_N_DV_NTSC
.It Dv IEC61883_RATE_D_DV_NTSC
Data rate expected by
.Sy DV-NTSC
devices.
.Pp
.It Dv IEC61883_RATE_N_DV_PAL
.It Dv IEC61883_RATE_D_DV_PAL
Data rate expected by
.Sy DV-PAL
devices.
.El
.Pp
During data transmission, a timestamp based on the current value of the cycle
timer is usually required.
.Fa ii_ts_mode
defines timestamp mode to be used:
.Bl -tag -width IEC61883_TS_NONE
.It Dv IEC61883_TS_SYT
Driver puts a timestamp in the SYT field of the first CIP header of each frame.
.It Dv IEC61883_TS_NONE
No timestamps.
.El
.Pp
.Fa ii_dbs ,
.Fa ii_fn ,
.Fa ii_rate_n ,
.Fa ii_rate_d
and
.Fa ii_ts_mode
are only required for transmission.
In other case these should be set to 0.
.Pp
.Fa ii_flags
should be set to 0.
.Pp
If command succeeds,
.Fa ii_handle
contains a handle that should be used with other isochronous commands.
.Fa ii_frame_rcnt
contains the number of allocated frames (can be less than
.Fa ii_frame_cnt ) .
.Fa ii_mmap_off
contains an offset to be used in
.Xr mmap 2 ,
for example, to map an entire data receive buffer:
.Bd -literal -offset 2n
pa = mmap(NULL, init.ii_pkt_size *
      init.ii_frame_size * init.ii_frame_rcnt,
      PROT_READ, MAP_PRIVATE, fd, init.ii_mmap_off);
.Ed
.Pp
.Fa ii_rchannel
contains channel number.
.Pp
In case of command success,
.Fa ii_error
is set to 0; otherwise one of the following values can be returned:
.Bl -tag -width IEC61883_ERR_NOCHANNEL
.It Dv IEC61883_ERR_NOMEM
Not enough memory for the data buffer.
.It Dv IEC61883_ERR_NOCHANNEL
Cannot allocate isochronous channel.
.It Dv IEC61883_ERR_PKT_SIZE
Packet size is not allowed at this bus speed.
.It Dv IEC61883_ERR_VERSION
Interface version is not supported.
.It Dv IEC61883_ERR_INVAL
One or more the parameters are invalid
.It Dv IEC61883_ERR_OTHER
Unspecified error type.
.El
.It Dv IEC61883_ISOCH_FINI
.Pp
Argument is a handle returned by
.Dv IEC61883_ISOCH_INIT .
This command frees any resources associated with this handle.
There must be no active transfers
and the data buffer must be unmapped; otherwise the command fails.
.It Dv IEC61883_START
.Pp
This command starts an isochronous transfer.
The argument is a handle returned
by
.Dv IEC61883_ISOCH_INIT .
.It Dv IEC61883_STOP
.Pp
This command stops an isochronous transfer.
The argument is a handle returned by
.Dv IEC61883_ISOCH_INIT .
.It Dv IEC61883_RECV
.Pp
This command is used to receive full frames and return empty frames to the driver.
The argument is a pointer to the structure:
.Bd -literal -offset 2n
typedef struct iec61883_recv {
        int   rx_handle;    /* isoch handle */
        int   rx_flags;     /* flags */
        iec61883_xfer_t rx_xfer;   /* xfer params */
} iec61883_recv_t;

typedef struct iec61883_xfer {
        int   xf_empty_idx; /* first empty frame */
        int   xf_empty_cnt; /* empty frame count */
        int   xf_full_idx;  /* first full frame */
        int   xf_full_cnt;  /* full frame count */
        int   xf_error;     /* error */
} iec61883_xfer_t;
.Ed
.Pp
.Fa rx_flags
should be set to 0.
.Pp
An application sets
.Fa xf_empty_idx
and
.Fa xf_empty_cnt
to indicate frames it no longer needs.
E. g.  if a buffer consists of 6 frames,
.Fa xf_empty_idx
is 4,
.Fa xf_empty_cnt
is 3 - means that frames 4, 5 and 0 can now be reused by the driver.
If there are no empty frames, for example, the
first time this command is called,
.Fa xf_empty_cnt
should be set to 0.
.Pp
When the command returns,
.Fa xf_full_idx
and
.Fa xf_full_cnt
specifies the frames that are full.
.Fa xf_error
is always 0.
.Pp
In general, AV frame boundaries are not aligned with the frame buffer
boundaries, because the first received packet might not be the first packet of
an AV frame, and, in contrast with the read/write method, the driver does not
remove empty CIP packets.
.Pp
Applications should detect empty packets by comparing adjacent packets'
continuity counters (DBC field of the CIP header).
.It Dv IEC61883_XMIT
.Pp
This command is used to transmit full frames and get more empty frames from the
driver.
The argument is a pointer to the structure:
.Bd -literal -offset 2n
typedef struct iec61883_xmit {
        int   tx_handle;         /* isoch handle */
        int   tx_flags;          /* flags */
        iec61883_xfer_t tx_xfer; /* xfer params */
        int   tx_miss_cnt;       /* missed cycles */
 } iec61883_xmit_t;
.Ed
.Pp
.Fa tx_flags
should be set to zero.
.Pp
The application sets
.Fa xf_full_idx
and
.Fa xf_full_cnt
to specify frames it wishes to transmit.
If there are no frames to transmit (e. g. the first time this command is called),
.Fa xf_full_cnt
should be set to 0.
.Pp
When the command returns,
.Fa xf_empty_idx
and
.Fa xf_empty_cnt
specifies empty frames which can be to transmit more data.
.Fa xf_error
is always 0.
.Pp
.Fa tx_miss_cnt
contains the number of isochronous cycles missed since last
transfer due to data buffer under run.
This can happen when an application does not supply data fast enough.
For the purposes of time stamping, the driver considers the first packet in a
frame buffer to be the first packet of an AV frame.
.It Dv IEC61883_PLUG_INIT
.Pp
This command returns a handle for the specified plug.
The argument is a pointer
to the structure:
.Bd -literal -offset 2n
typedef struct iec61883_plug_init {
        int   pi_ver;     /* interface version */
        int   pi_loc;     /* plug location */
        int   pi_type;    /* plug type */
        int   pi_num;     /* plug number */
        int   pi_flags;   /* flags */
        int   pi_handle;  /* plug handle */
        int   pi_rnum;    /* plug number */
 } iec61883_plug_init_t;
.Ed
.Pp
.Fa pi_ver
should be set to
.Dv IEC61883_V1_0 .
.Pp
.Fa pi_loc
specifies plug location:
.Bl -tag -width IEC61883_LOC_REMOTE
.It Dv IEC61883_LOC_LOCAL
On the local unit (local plug).
A plug control register (PCR) is allocated.
Command fails if the plug already exists
.It Dv IEC61883_LOC_REMOTE
On the remote unit (remote plug).
The plug should exist on the remote unit,
otherwise the command fails.
.El
.Pp
.Fa pi_type
specifies isochronous plug type:
.Pp
.Bl -tag -width " " -compact
.It Dv IEC61883_PLUG_IN
.It Dv IEC61883_PLUG_OUT
.Pp
Input or output plugs.
.Pp
.It Dv IEC61883_PLUG_MASTER_IN
.It Dv IEC61883_PLUG_MASTER_OUT
.Pp
Master input or master output plug.
These plugs always exist on the local unit.
.El
.Pp
.Fa pi_num
specifies plug number.
This should be 0 for master plugs, and from 0 to 31 for input/output plugs.
Alternatively, a special value
.Dv IEC61883_PLUG_ANY
can be used to let the driver choose a free plug
number, create the plug and return the number in
.Fa pi_rnum .
.Pp
.Fa pi_flags
should be set to 0.
.Pp
If the command succeeds,
.Fa pi_handle
contains a handle that should be used with other plug commands.
.It Dv IEC61883_PLUG_FINI
.Pp
Argument is a handle returned by
.Dv IEC61883_PLUG_INIT .
This command frees any resources associated with this handle, including the PCR.
.It Dv IEC61883_PLUG_REG_READ
.Pp
Read plug register value.
The argument is a pointer to the structure:
.Bd -literal -offset 2n
typedef struct iec61883_plug_reg_val {
        int         pr_handle; /* plug handle */
        uint32_t    pr_val;    /* register value */
} iec61883_plug_reg_val_t;
.Ed
.Pp
.Fa pr_handle
is a handle returned by
.Dv IEC61883_PLUG_INIT .
Register
value is returned in
.Fa pr_val .
.It Dv IEC61883_PLUG_REG_CAS
.Pp
Atomically compare and swap plug register value.
The argument is a pointer to the structure:
.Bd -literal -offset 2n
typedef struct iec61883_plug_reg_lock {
        int        pl_handle; /* plug handle */
        uint32_t   pl_arg;    /* compare arg */
        uint32_t   pl_data;   /* write value */
        UINT32_t   pl_old;    /* original value */
} iec61883_plug_reg_lock_t;
.Ed
.Pp
.Fa pr_handle
is a handle returned by IEC61883_PLUG_INIT.
.Pp
Original register value is compared with
.Fa pl_arg
and if they are equal, register value is replaced with
.Fa pl_data .
In any case, the original value is stored in
.Fa pl_old .
.El
.Pp
The following commands only apply to asynchronous nodes:
.Bl -tag -width " "
.It Dv IEC61883_ARQ_GET_IBUF_SIZE
.Pp
This command returns current incoming ARQ buffer size.
The argument is a
pointer to
.Vt int .
.It Dv IEC61883_ARQ_SET_IBUF_SIZE
.Pp
This command changes incoming ARQ buffer size.
The argument is the new buffer
size in bytes.
.El
.Sh FILES
.Bl -tag -width /dev/av/N/async
.It Pa /dev/av/N/async
Device node for asynchronous data
.It Pa /dev/av/N/isoch
Device has been disconnected
.El
.Sh ERRORS
.Bl -tag -width EFAULT
.It Er EIO
Bus operation failed.
DMA failure.
.It Er EFAULT
.Xr ioctl 2
argument points to an illegal address.
.It Er EINVAL
Invalid argument or argument combination.
.It Er ENODEV
Device has been disconnected.
.El
.Sh ARCHITECTURE
All
.Sh INTERFACE STABILITY
Committed
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr mmap 2 ,
.Xr open 2 ,
.Xr poll 2 ,
.Xr read 2 ,
.Xr write 2 ,
.Xr av1394 4D ,
.Xr attributes 7
.Rs
.%B IIEC 61883 Consumer audio/video equipment - Digital interface
.Re
.Rs
.%B IEEE Std 1394-1995 Standard for a High Performance Serial Bus
.Re