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 from the given endpoint.
81 one becomes available (i.e. until the remote processor consumes
93 sends a message across to the remote processor from a given endpoint,
99 The message will then be sent to the remote processor to which the
105 one becomes available (i.e. until the remote processor consumes
119 sends a message across to the remote processor, using the src and dst
124 The message will then be sent to the remote processor to which the
130 one becomes available (i.e. until the remote processor consumes
142 sends a message across to the remote processor from a given endpoint.
160 sends a message across to the remote processor from a given endpoint,
166 The message will then be sent to the remote processor to which the
182 sends a message across to the remote processor, using source and
187 The message will then be sent to the remote processor to which the
226 to the same remote processor their channel belongs to), an rx callback
330 This is possible only with remote processors that have the VIRTIO_RPMSG_F_NS
331 virtio device feature set. This feature bit means that the remote
335 is completely dynamic: the remote processor announces the existence of a
336 remote rpmsg service by sending a name service message (which contains
337 the name and rpmsg addr of the remote service, see struct rpmsg_ns_msg).
340 creates and registers an rpmsg channel (which represents the remote service).
342 by the bus, and can then start sending messages to the remote service.