rapidio: add RapidIO channelized messaging driver

RapidIO subsystem Channelized Messaging character device driver (rio_cm.c)

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Version History:

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  1.0.0 - Initial driver release.

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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).

endchoice

config RAPIDIO_CHMAN

	tristate "RapidIO Channelized Messaging driver"

	depends on RAPIDIO

	help

	  This option includes RapidIO channelized messaging driver which

	  provides socket-like interface to allow sharing of single RapidIO

	  messaging mailbox between multiple user-space applications.

	  See "Documentation/rapidio/rio_cm.txt" for driver description.

config RAPIDIO_MPORT_CDEV

	tristate "RapidIO /dev mport device driver"

	depends on RAPIDIO

rapidio-y := rio.o rio-access.o rio-driver.o rio-sysfs.o

obj-$(CONFIG_RAPIDIO_ENUM_BASIC) += rio-scan.o

obj-$(CONFIG_RAPIDIO_CHMAN)	+= rio_cm.o

obj-$(CONFIG_RAPIDIO)		+= switches/

obj-$(CONFIG_RAPIDIO)		+= devices/

header-y += reiserfs_xattr.h

header-y += resource.h

header-y += rfkill.h

header-y += rio_cm_cdev.h

header-y += rio_mport_cdev.h

header-y += romfs_fs.h

header-y += rose.h