rio_cm.rst (5963B)
1========================================================================== 2RapidIO subsystem Channelized Messaging character device driver (rio_cm.c) 3========================================================================== 4 5 61. Overview 7=========== 8 9This device driver is the result of collaboration within the RapidIO.org 10Software Task Group (STG) between Texas Instruments, Prodrive Technologies, 11Nokia Networks, BAE and IDT. Additional input was received from other members 12of RapidIO.org. 13 14The objective was to create a character mode driver interface which exposes 15messaging capabilities of RapidIO endpoint devices (mports) directly 16to applications, in a manner that allows the numerous and varied RapidIO 17implementations to interoperate. 18 19This driver (RIO_CM) provides to user-space applications shared access to 20RapidIO mailbox messaging resources. 21 22RapidIO specification (Part 2) defines that endpoint devices may have up to four 23messaging mailboxes in case of multi-packet message (up to 4KB) and 24up to 64 mailboxes if single-packet messages (up to 256 B) are used. In addition 25to protocol definition limitations, a particular hardware implementation can 26have reduced number of messaging mailboxes. RapidIO aware applications must 27therefore share the messaging resources of a RapidIO endpoint. 28 29Main purpose of this device driver is to provide RapidIO mailbox messaging 30capability to large number of user-space processes by introducing socket-like 31operations using a single messaging mailbox. This allows applications to 32use 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_cm 37in /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 that 43 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 RapidIO 45 destination ID assigned to the port. 46- RIO_CM_EP_GET_LIST_SIZE: 47 Returns number of messaging capable remote endpoints 48 in a RapidIO network associated with the specified mport device. 49- RIO_CM_EP_GET_LIST: 50 Returns list of RapidIO destination IDs for messaging 51 capable remote endpoints (peers) available in a RapidIO network associated 52 with the specified mport device. 53- RIO_CM_CHAN_CREATE: 54 Creates RapidIO message exchange channel data structure 55 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 specified 58 mport device. 59- RIO_CM_CHAN_LISTEN: 60 Enables listening for connection requests on the specified 61 channel. 62- RIO_CM_CHAN_ACCEPT: 63 Accepts a connection request from peer on the specified 64 channel. If wait timeout for this request is specified by a caller it is 65 a blocking call. If timeout set to 0 this is non-blocking call - ioctl 66 handler checks for a pending connection request and if one is not available 67 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 by 73 a caller includes the reserved space for a packet header required by 74 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 ioctl 78 handler will wait for new message until timeout specified by a caller 79 expires. If timeout value is set to 0, ioctl handler uses a default value 80 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 notification 84 to the remote peer. 85 86The ioctl command codes and corresponding data structures intended for use by 87user-space applications are defined in 'include/uapi/linux/rio_cm_cdev.h'. 88 892. Hardware Compatibility 90========================= 91 92This device driver uses standard interfaces defined by kernel RapidIO subsystem 93and therefore it can be used with any mport device driver registered by RapidIO 94subsystem with limitations set by available mport HW implementation of messaging 95mailboxes. 96 973. Module parameters 98==================== 99 100- 'dbg_level' 101 - This parameter allows to control amount of debug information 102 generated by this device driver. This parameter is formed by set of 103 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 used 111 within entire RapidIO network. It can be used when default mailbox is 112 used by other device drivers or is not supported by some nodes in the 113 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 dynamic 118 allocation to avoid conflicts with software components that use 119 reserved predefined channel numbers. 120 1214. Known problems 122================= 123 124 None. 125 1265. User-space Applications and API Library 127========================================== 128 129Messaging API library and applications that use this device driver are available 130from RapidIO.org. 131 1326. TODO List 133============ 134 135- Add support for system notification messages (reserved channel 0).