Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 119 insertions, 0 deletions

diff --git a/Documentation/rapidio/rio_cm.txt b/Documentation/rapidio/rio_cm.txt
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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).