4 Contact: linux1394-devel@lists.sourceforge.net
6 The character device files /dev/fw* are the interface between
7 firewire-core and IEEE 1394 device drivers implemented in
8 userspace. The ioctl(2)- and read(2)-based ABI is defined and
9 documented in <linux/firewire-cdev.h>.
11 This ABI offers most of the features which firewire-core also
12 exposes to kernelspace IEEE 1394 drivers.
14 Each /dev/fw* is associated with one IEEE 1394 node, which can
15 be remote or local nodes. Operations on a /dev/fw* file have
18 - The 1394 node which is associated with the file:
19 - Asynchronous request transmission
20 - Get the Configuration ROM
22 - Query maximum speed of the path between this node
25 - The 1394 bus (i.e. "card") to which the node is attached to:
26 - Isochronous stream transmission and reception
27 - Asynchronous stream transmission and reception
28 - Asynchronous broadcast request transmission
29 - PHY packet transmission and reception
30 - Allocate, reallocate, deallocate isochronous
31 resources (channels, bandwidth) at the bus's IRM
32 - Query node IDs of local node, root node, IRM, bus
35 - Bus reset initiation, bus reset event reception
38 - Allocation of IEEE 1212 address ranges on the local
39 link layers, reception of inbound requests to such
40 an address range, asynchronous response transmission
42 - Addition of descriptors or directories to the local
43 nodes' Configuration ROM
45 Due to the different scope of operations and in order to let
46 userland implement different access permission models, some
47 operations are restricted to /dev/fw* files that are associated
50 - Addition of descriptors or directories to the local
51 nodes' Configuration ROM
52 - PHY packet transmission and reception
54 A /dev/fw* file remains associated with one particular node
55 during its entire life time. Bus topology changes, and hence
56 node ID changes, are tracked by firewire-core. ABI users do not
57 need to be aware of topology.
59 The following file operations are supported:
62 Currently the only useful flags are O_RDWR.
65 Initiate various actions. Some take immediate effect, others
66 are performed asynchronously while or after the ioctl returns.
67 See the inline documentation in <linux/firewire-cdev.h> for
68 descriptions of all ioctls.
70 poll(2), select(2), epoll_wait(2) etc.
71 Watch for events to become available to be read.
74 Receive various events. There are solicited events like
75 outbound asynchronous transaction completion or isochronous
76 buffer completion, and unsolicited events such as bus resets,
77 request reception, or PHY packet reception. Always use a read
78 buffer which is large enough to receive the largest event that
79 could ever arrive. See <linux/firewire-cdev.h> for descriptions
80 of all event types and for which ioctls affect reception of
84 Allocate a DMA buffer for isochronous reception or transmission
85 and map it into the process address space. The arguments should
86 be used as follows: addr = NULL, length = the desired buffer
87 size, i.e. number of packets times size of largest packet,
88 prot = at least PROT_READ for reception and at least PROT_WRITE
89 for transmission, flags = MAP_SHARED, fd = the handle to the
92 Isochronous reception works in packet-per-buffer fashion except
93 for multichannel reception which works in buffer-fill mode.
96 Unmap the isochronous I/O buffer from the process address space.
99 Besides stopping and freeing I/O contexts that were associated
100 with the file descriptor, back out any changes to the local
101 nodes' Configuration ROM. Deallocate isochronous channels and
102 bandwidth at the IRM that were marked for kernel-assisted
103 re- and deallocation.
108 tools like linux-firewire-utils, fwhack, ...