What:		/dev/fw[0-9]+Date:		May 2007KernelVersion:	2.6.22Contact:	linux1394-devel@lists.sourceforge.netDescription:		The character device files /dev/fw* are the interface between		firewire-core and IEEE 1394 device drivers implemented in		userspace.  The ioctl(2)- and read(2)-based ABI is defined and		documented in <linux/firewire-cdev.h>. 		This ABI offers most of the features which firewire-core also		exposes to kernelspace IEEE 1394 drivers. 		Each /dev/fw* is associated with one IEEE 1394 node, which can		be remote or local nodes.  Operations on a /dev/fw* file have		different scope: 		  - The 1394 node which is associated with the file: 			  - Asynchronous request transmission			  - Get the Configuration ROM			  - Query node ID			  - Query maximum speed of the path between this node			    and local node 		  - The 1394 bus (i.e. "card") to which the node is attached to: 			  - Isochronous stream transmission and reception			  - Asynchronous stream transmission and reception			  - Asynchronous broadcast request transmission			  - PHY packet transmission and reception			  - Allocate, reallocate, deallocate isochronous			    resources (channels, bandwidth) at the bus's IRM			  - Query node IDs of local node, root node, IRM, bus			    manager			  - Query cycle time			  - Bus reset initiation, bus reset event reception 		  - All 1394 buses: 			  - Allocation of IEEE 1212 address ranges on the local			    link layers, reception of inbound requests to such			    an address range, asynchronous response transmission			    to inbound requests			  - Addition of descriptors or directories to the local			    nodes' Configuration ROM 		Due to the different scope of operations and in order to let		userland implement different access permission models, some		operations are restricted to /dev/fw* files that are associated		with a local node: 			  - Addition of descriptors or directories to the local			    nodes' Configuration ROM			  - PHY packet transmission and reception 		A /dev/fw* file remains associated with one particular node		during its entire life time.  Bus topology changes, and hence		node ID changes, are tracked by firewire-core.  ABI users do not		need to be aware of topology. 		The following file operations are supported: 		open(2)		    Currently the only useful flags are O_RDWR. 		ioctl(2)		    Initiate various actions.  Some take immediate effect, others		    are performed asynchronously while or after the ioctl returns.		    See the inline documentation in <linux/firewire-cdev.h> for		    descriptions of all ioctls. 		poll(2), select(2), epoll_wait(2) etc.		    Watch for events to become available to be read. 		read(2)		    Receive various events.  There are solicited events like		    outbound asynchronous transaction completion or isochronous		    buffer completion, and unsolicited events such as bus resets,		    request reception, or PHY packet reception.  Always use a read		    buffer which is large enough to receive the largest event that		    could ever arrive.  See <linux/firewire-cdev.h> for descriptions		    of all event types and for which ioctls affect reception of		    events. 		mmap(2)		    Allocate a DMA buffer for isochronous reception or transmission		    and map it into the process address space.  The arguments should		    be used as follows:  addr = NULL, length = the desired buffer		    size, i.e. number of packets times size of largest packet,		    prot = at least PROT_READ for reception and at least PROT_WRITE		    for transmission, flags = MAP_SHARED, fd = the handle to the		    /dev/fw*, offset = 0. 		Isochronous reception works in packet-per-buffer fashion except		for multichannel reception which works in buffer-fill mode. 		munmap(2)		    Unmap the isochronous I/O buffer from the process address space. 		close(2)		    Besides stopping and freeing I/O contexts that were associated		    with the file descriptor, back out any changes to the local		    nodes' Configuration ROM.  Deallocate isochronous channels and		    bandwidth at the IRM that were marked for kernel-assisted		    re- and deallocation. Users:		libraw1394;		libdc1394;		libhinawa;		tools like linux-firewire-utils, fwhack, ...