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+RapidIO subsystem Channelized Messaging character device driver (rio_cm.c)
+==========================================================================
+
+Version History:
+----------------
+ 1.0.0 - Initial driver release.
+
+==========================================================================
+
+I. Overview
+
+This device driver is the result of collaboration within the RapidIO.org
+Software Task Group (STG) between Texas Instruments, Prodrive Technologies,
+Nokia Networks, BAE and IDT. Additional input was received from other members
+of RapidIO.org.
+
+The objective was to create a character mode driver interface which exposes
+messaging capabilities of RapidIO endpoint devices (mports) directly
+to applications, in a manner that allows the numerous and varied RapidIO
+implementations to interoperate.
+
+This driver (RIO_CM) provides to user-space applications shared access to
+RapidIO mailbox messaging resources.
+
+RapidIO specification (Part 2) defines that endpoint devices may have up to four
+messaging mailboxes in case of multi-packet message (up to 4KB) and
+up to 64 mailboxes if single-packet messages (up to 256 B) are used. In addition
+to protocol definition limitations, a particular hardware implementation can
+have reduced number of messaging mailboxes. RapidIO aware applications must
+therefore share the messaging resources of a RapidIO endpoint.
+
+Main purpose of this device driver is to provide RapidIO mailbox messaging
+capability to large number of user-space processes by introducing socket-like
+operations using a single messaging mailbox. This allows applications to
+use the limited RapidIO messaging hardware resources efficiently.
+
+Most of device driver's operations are supported through 'ioctl' system calls.
+
+When loaded this device driver creates a single file system node named rio_cm
+in /dev directory common for all registered RapidIO mport devices.
+
+Following ioctl commands are available to user-space applications:
+
+- RIO_CM_MPORT_GET_LIST : Returns to caller list of local mport devices that
+ support messaging operations (number of entries up to RIO_MAX_MPORTS).
+ Each list entry is combination of mport's index in the system and RapidIO
+ destination ID assigned to the port.
+- RIO_CM_EP_GET_LIST_SIZE : Returns number of messaging capable remote endpoints
+ in a RapidIO network associated with the specified mport device.
+- RIO_CM_EP_GET_LIST : Returns list of RapidIO destination IDs for messaging
+ capable remote endpoints (peers) available in a RapidIO network associated
+ with the specified mport device.
+- RIO_CM_CHAN_CREATE : Creates RapidIO message exchange channel data structure
+ with channel ID assigned automatically or as requested by a caller.
+- RIO_CM_CHAN_BIND : Binds the specified channel data structure to the specified
+ mport device.
+- RIO_CM_CHAN_LISTEN : Enables listening for connection requests on the specified
+ channel.
+- RIO_CM_CHAN_ACCEPT : Accepts a connection request from peer on the specified
+ channel. If wait timeout for this request is specified by a caller it is
+ a blocking call. If timeout set to 0 this is non-blocking call - ioctl
+ handler checks for a pending connection request and if one is not available
+ exits with -EGAIN error status immediately.
+- RIO_CM_CHAN_CONNECT : Sends a connection request to a remote peer/channel.
+- RIO_CM_CHAN_SEND : Sends a data message through the specified channel.
+ The handler for this request assumes that message buffer specified by
+ a caller includes the reserved space for a packet header required by
+ this driver.
+- RIO_CM_CHAN_RECEIVE : Receives a data message through a connected channel.
+ If the channel does not have an incoming message ready to return this ioctl
+ handler will wait for new message until timeout specified by a caller
+ expires. If timeout value is set to 0, ioctl handler uses a default value
+ defined by MAX_SCHEDULE_TIMEOUT.
+- RIO_CM_CHAN_CLOSE : Closes a specified channel and frees associated buffers.
+ If the specified channel is in the CONNECTED state, sends close notification
+ to the remote peer.
+
+The ioctl command codes and corresponding data structures intended for use by
+user-space applications are defined in 'include/uapi/linux/rio_cm_cdev.h'.
+
+II. Hardware Compatibility
+
+This device driver uses standard interfaces defined by kernel RapidIO subsystem
+and therefore it can be used with any mport device driver registered by RapidIO
+subsystem with limitations set by available mport HW implementation of messaging
+mailboxes.
+
+III. Module parameters
+
+- 'dbg_level' - This parameter allows to control amount of debug information
+ generated by this device driver. This parameter is formed by set of
+ bit masks that correspond to the specific functional block.
+ For mask definitions see 'drivers/rapidio/devices/rio_cm.c'
+ This parameter can be changed dynamically.
+ Use CONFIG_RAPIDIO_DEBUG=y to enable debug output at the top level.
+
+- 'cmbox' - Number of RapidIO mailbox to use (default value is 1).
+ This parameter allows to set messaging mailbox number that will be used
+ within entire RapidIO network. It can be used when default mailbox is
+ used by other device drivers or is not supported by some nodes in the
+ RapidIO network.
+
+- 'chstart' - Start channel number for dynamic assignment. Default value - 256.
+ Allows to exclude channel numbers below this parameter from dynamic
+ allocation to avoid conflicts with software components that use
+ reserved predefined channel numbers.
+
+IV. Known problems
+
+ None.
+
+V. User-space Applications and API Library
+
+Messaging API library and applications that use this device driver are available
+from RapidIO.org.
+
+VI. TODO List
+
+- Add support for system notification messages (reserved channel 0).