Documentation/staging/rpmsg.rst

2 Remote Processor Messaging (rpmsg) Framework
14 Modern SoCs typically employ heterogeneous remote processor devices in
24 Typically AMP remote processors employ dedicated DSP codecs and multimedia
28 These remote processors could also be used to control latency-sensitive
32 Users of those remote processors can either be userland apps (e.g. multimedia
33 frameworks talking with remote OMX components) or kernel drivers (controlling
34 hardware accessible only by the remote processor, reserving kernel-controlled
35 resources on behalf of the remote processor, etc..).
38 with remote processors available on the system. In turn, drivers could then
42 keep in mind that remote processors might have direct access to the
44 OMAP4, remote cores and hardware accelerators may have direct access to the
46 devices, hwspinlocks, etc..). Moreover, those remote processors might be
49 exploiting remote bugs, and by that taking over the system, it is often
54 Every rpmsg device is a communication channel with a remote processor (thus
56 and have a local ("source") rpmsg address, and remote ("destination") rpmsg
73 sends a message across to the remote processor on a given channel.
80 one becomes available (i.e. until the remote processor consumes
92 sends a message across to the remote processor on a given channel,
98 The message will then be sent to the remote processor to which the
103 one becomes available (i.e. until the remote processor consumes
117 sends a message across to the remote processor, using the src and dst
122 The message will then be sent to the remote processor to which the
127 one becomes available (i.e. until the remote processor consumes
139 sends a message across to the remote processor on a given channel.
156 sends a message across to the remote processor on a given channel,
162 The message will then be sent to the remote processor to which the
178 sends a message across to the remote processor, using source and
183 The message will then be sent to the remote processor to which the
222 to the same remote processor their channel belongs to), an rx callback
326 This is possible only with remote processors that have the VIRTIO_RPMSG_F_NS
327 virtio device feature set. This feature bit means that the remote
331 is completely dynamic: the remote processor announces the existence of a
332 remote rpmsg service by sending a name service message (which contains
333 the name and rpmsg addr of the remote service, see struct rpmsg_ns_msg).
336 creates and registers an rpmsg channel (which represents the remote service).
338 by the bus, and can then start sending messages to the remote service.