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author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-08-03 03:08:07 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-08-03 03:08:07 +0200 |
commit | d52bd54db8be8999df6df5a776f38c4f8b5e9cea (patch) | |
tree | 0d8f436e959bb975c002ddf12ea1bdc9adadd04f /Documentation/rapidio/rio_cm.txt | |
parent | Merge tag 'for-linus-v4.8' of git://github.com/martinbrandenburg/linux (diff) | |
parent | ipc: delete "nr_ipc_ns" (diff) | |
download | linux-d52bd54db8be8999df6df5a776f38c4f8b5e9cea.tar.xz linux-d52bd54db8be8999df6df5a776f38c4f8b5e9cea.zip |
Merge branch 'akpm' (patches from Andrew)
Merge yet more updates from Andrew Morton:
- the rest of ocfs2
- various hotfixes, mainly MM
- quite a bit of misc stuff - drivers, fork, exec, signals, etc.
- printk updates
- firmware
- checkpatch
- nilfs2
- more kexec stuff than usual
- rapidio updates
- w1 things
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (111 commits)
ipc: delete "nr_ipc_ns"
kcov: allow more fine-grained coverage instrumentation
init/Kconfig: add clarification for out-of-tree modules
config: add android config fragments
init/Kconfig: ban CONFIG_LOCALVERSION_AUTO with allmodconfig
relay: add global mode support for buffer-only channels
init: allow blacklisting of module_init functions
w1:omap_hdq: fix regression
w1: add helper macro module_w1_family
w1: remove need for ida and use PLATFORM_DEVID_AUTO
rapidio/switches: add driver for IDT gen3 switches
powerpc/fsl_rio: apply changes for RIO spec rev 3
rapidio: modify for rev.3 specification changes
rapidio: change inbound window size type to u64
rapidio/idt_gen2: fix locking warning
rapidio: fix error handling in mbox request/release functions
rapidio/tsi721_dma: advance queue processing from transfer submit call
rapidio/tsi721: add messaging mbox selector parameter
rapidio/tsi721: add PCIe MRRS override parameter
rapidio/tsi721_dma: add channel mask and queue size parameters
...
Diffstat (limited to 'Documentation/rapidio/rio_cm.txt')
-rw-r--r-- | Documentation/rapidio/rio_cm.txt | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/Documentation/rapidio/rio_cm.txt b/Documentation/rapidio/rio_cm.txt new file mode 100644 index 000000000000..27aa401f1126 --- /dev/null +++ b/Documentation/rapidio/rio_cm.txt @@ -0,0 +1,119 @@ +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). |