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1==========================================================================2RapidIO subsystem Channelized Messaging character device driver (rio_cm.c)3==========================================================================4 5 61. Overview7===========8 9This device driver is the result of collaboration within the RapidIO.org10Software Task Group (STG) between Texas Instruments, Prodrive Technologies,11Nokia Networks, BAE and IDT. Additional input was received from other members12of RapidIO.org.13 14The objective was to create a character mode driver interface which exposes15messaging capabilities of RapidIO endpoint devices (mports) directly16to applications, in a manner that allows the numerous and varied RapidIO17implementations to interoperate.18 19This driver (RIO_CM) provides to user-space applications shared access to20RapidIO mailbox messaging resources.21 22RapidIO specification (Part 2) defines that endpoint devices may have up to four23messaging mailboxes in case of multi-packet message (up to 4KB) and24up to 64 mailboxes if single-packet messages (up to 256 B) are used. In addition25to protocol definition limitations, a particular hardware implementation can26have reduced number of messaging mailboxes. RapidIO aware applications must27therefore share the messaging resources of a RapidIO endpoint.28 29Main purpose of this device driver is to provide RapidIO mailbox messaging30capability to large number of user-space processes by introducing socket-like31operations using a single messaging mailbox. This allows applications to32use the limited RapidIO messaging hardware resources efficiently.33 34Most of device driver's operations are supported through 'ioctl' system calls.35 36When loaded this device driver creates a single file system node named rio_cm37in /dev directory common for all registered RapidIO mport devices.38 39Following ioctl commands are available to user-space applications:40 41- RIO_CM_MPORT_GET_LIST:42 Returns to caller list of local mport devices that43 support messaging operations (number of entries up to RIO_MAX_MPORTS).44 Each list entry is combination of mport's index in the system and RapidIO45 destination ID assigned to the port.46- RIO_CM_EP_GET_LIST_SIZE:47 Returns number of messaging capable remote endpoints48 in a RapidIO network associated with the specified mport device.49- RIO_CM_EP_GET_LIST:50 Returns list of RapidIO destination IDs for messaging51 capable remote endpoints (peers) available in a RapidIO network associated52 with the specified mport device.53- RIO_CM_CHAN_CREATE:54 Creates RapidIO message exchange channel data structure55 with channel ID assigned automatically or as requested by a caller.56- RIO_CM_CHAN_BIND:57 Binds the specified channel data structure to the specified58 mport device.59- RIO_CM_CHAN_LISTEN:60 Enables listening for connection requests on the specified61 channel.62- RIO_CM_CHAN_ACCEPT:63 Accepts a connection request from peer on the specified64 channel. If wait timeout for this request is specified by a caller it is65 a blocking call. If timeout set to 0 this is non-blocking call - ioctl66 handler checks for a pending connection request and if one is not available67 exits with -EGAIN error status immediately.68- RIO_CM_CHAN_CONNECT:69 Sends a connection request to a remote peer/channel.70- RIO_CM_CHAN_SEND:71 Sends a data message through the specified channel.72 The handler for this request assumes that message buffer specified by73 a caller includes the reserved space for a packet header required by74 this driver.75- RIO_CM_CHAN_RECEIVE:76 Receives a data message through a connected channel.77 If the channel does not have an incoming message ready to return this ioctl78 handler will wait for new message until timeout specified by a caller79 expires. If timeout value is set to 0, ioctl handler uses a default value80 defined by MAX_SCHEDULE_TIMEOUT.81- RIO_CM_CHAN_CLOSE:82 Closes a specified channel and frees associated buffers.83 If the specified channel is in the CONNECTED state, sends close notification84 to the remote peer.85 86The ioctl command codes and corresponding data structures intended for use by87user-space applications are defined in 'include/uapi/linux/rio_cm_cdev.h'.88 892. Hardware Compatibility90=========================91 92This device driver uses standard interfaces defined by kernel RapidIO subsystem93and therefore it can be used with any mport device driver registered by RapidIO94subsystem with limitations set by available mport HW implementation of messaging95mailboxes.96 973. Module parameters98====================99 100- 'dbg_level'101 - This parameter allows to control amount of debug information102 generated by this device driver. This parameter is formed by set of103 bit masks that correspond to the specific functional block.104 For mask definitions see 'drivers/rapidio/devices/rio_cm.c'105 This parameter can be changed dynamically.106 Use CONFIG_RAPIDIO_DEBUG=y to enable debug output at the top level.107 108- 'cmbox'109 - Number of RapidIO mailbox to use (default value is 1).110 This parameter allows to set messaging mailbox number that will be used111 within entire RapidIO network. It can be used when default mailbox is112 used by other device drivers or is not supported by some nodes in the113 RapidIO network.114 115- 'chstart'116 - Start channel number for dynamic assignment. Default value - 256.117 Allows to exclude channel numbers below this parameter from dynamic118 allocation to avoid conflicts with software components that use119 reserved predefined channel numbers.120 1214. Known problems122=================123 124 None.125 1265. User-space Applications and API Library127==========================================128 129Messaging API library and applications that use this device driver are available130from RapidIO.org.131 1326. TODO List133============134 135- Add support for system notification messages (reserved channel 0).136