rpmsg.txt: standardize document format
Each text file under Documentation follows a different format. Some doesn't even have titles! Change its representation to follow the adopted standard, using ReST markups for it to be parseable by Sphinx: - mark document and chapter titles; - mark notes; - mark literal blocks; - adjust identation. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>hifive-unleashed-5.1
Mauro Carvalho Chehab
Jonathan Corbet
parent
773810d30e
commit
af3137f132
|
|
@ -1,10 +1,15 @@
|
||||||
|
============================================
|
||||||
Remote Processor Messaging (rpmsg) Framework
|
Remote Processor Messaging (rpmsg) Framework
|
||||||
|
============================================
|
||||||
|
|
||||||
Note: this document describes the rpmsg bus and how to write rpmsg drivers.
|
.. note::
|
||||||
To learn how to add rpmsg support for new platforms, check out remoteproc.txt
|
|
||||||
(also a resident of Documentation/).
|
|
||||||
|
|
||||||
1. Introduction
|
This document describes the rpmsg bus and how to write rpmsg drivers.
|
||||||
|
To learn how to add rpmsg support for new platforms, check out remoteproc.txt
|
||||||
|
(also a resident of Documentation/).
|
||||||
|
|
||||||
|
Introduction
|
||||||
|
============
|
||||||
|
|
||||||
Modern SoCs typically employ heterogeneous remote processor devices in
|
Modern SoCs typically employ heterogeneous remote processor devices in
|
||||||
asymmetric multiprocessing (AMP) configurations, which may be running
|
asymmetric multiprocessing (AMP) configurations, which may be running
|
||||||
|
|
@ -58,170 +63,222 @@ to their destination address (this is done by invoking the driver's rx handler
|
||||||
with the payload of the inbound message).
|
with the payload of the inbound message).
|
||||||
|
|
||||||
|
|
||||||
2. User API
|
User API
|
||||||
|
========
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
int rpmsg_send(struct rpmsg_channel *rpdev, void *data, int len);
|
int rpmsg_send(struct rpmsg_channel *rpdev, void *data, int len);
|
||||||
- sends a message across to the remote processor on a given channel.
|
|
||||||
The caller should specify the channel, the data it wants to send,
|
|
||||||
and its length (in bytes). The message will be sent on the specified
|
|
||||||
channel, i.e. its source and destination address fields will be
|
|
||||||
set to the channel's src and dst addresses.
|
|
||||||
|
|
||||||
In case there are no TX buffers available, the function will block until
|
sends a message across to the remote processor on a given channel.
|
||||||
one becomes available (i.e. until the remote processor consumes
|
The caller should specify the channel, the data it wants to send,
|
||||||
a tx buffer and puts it back on virtio's used descriptor ring),
|
and its length (in bytes). The message will be sent on the specified
|
||||||
or a timeout of 15 seconds elapses. When the latter happens,
|
channel, i.e. its source and destination address fields will be
|
||||||
-ERESTARTSYS is returned.
|
set to the channel's src and dst addresses.
|
||||||
The function can only be called from a process context (for now).
|
|
||||||
Returns 0 on success and an appropriate error value on failure.
|
In case there are no TX buffers available, the function will block until
|
||||||
|
one becomes available (i.e. until the remote processor consumes
|
||||||
|
a tx buffer and puts it back on virtio's used descriptor ring),
|
||||||
|
or a timeout of 15 seconds elapses. When the latter happens,
|
||||||
|
-ERESTARTSYS is returned.
|
||||||
|
|
||||||
|
The function can only be called from a process context (for now).
|
||||||
|
Returns 0 on success and an appropriate error value on failure.
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
int rpmsg_sendto(struct rpmsg_channel *rpdev, void *data, int len, u32 dst);
|
int rpmsg_sendto(struct rpmsg_channel *rpdev, void *data, int len, u32 dst);
|
||||||
- sends a message across to the remote processor on a given channel,
|
|
||||||
to a destination address provided by the caller.
|
|
||||||
The caller should specify the channel, the data it wants to send,
|
|
||||||
its length (in bytes), and an explicit destination address.
|
|
||||||
The message will then be sent to the remote processor to which the
|
|
||||||
channel belongs, using the channel's src address, and the user-provided
|
|
||||||
dst address (thus the channel's dst address will be ignored).
|
|
||||||
|
|
||||||
In case there are no TX buffers available, the function will block until
|
sends a message across to the remote processor on a given channel,
|
||||||
one becomes available (i.e. until the remote processor consumes
|
to a destination address provided by the caller.
|
||||||
a tx buffer and puts it back on virtio's used descriptor ring),
|
|
||||||
or a timeout of 15 seconds elapses. When the latter happens,
|
The caller should specify the channel, the data it wants to send,
|
||||||
-ERESTARTSYS is returned.
|
its length (in bytes), and an explicit destination address.
|
||||||
The function can only be called from a process context (for now).
|
|
||||||
Returns 0 on success and an appropriate error value on failure.
|
The message will then be sent to the remote processor to which the
|
||||||
|
channel belongs, using the channel's src address, and the user-provided
|
||||||
|
dst address (thus the channel's dst address will be ignored).
|
||||||
|
|
||||||
|
In case there are no TX buffers available, the function will block until
|
||||||
|
one becomes available (i.e. until the remote processor consumes
|
||||||
|
a tx buffer and puts it back on virtio's used descriptor ring),
|
||||||
|
or a timeout of 15 seconds elapses. When the latter happens,
|
||||||
|
-ERESTARTSYS is returned.
|
||||||
|
|
||||||
|
The function can only be called from a process context (for now).
|
||||||
|
Returns 0 on success and an appropriate error value on failure.
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
int rpmsg_send_offchannel(struct rpmsg_channel *rpdev, u32 src, u32 dst,
|
int rpmsg_send_offchannel(struct rpmsg_channel *rpdev, u32 src, u32 dst,
|
||||||
void *data, int len);
|
void *data, int len);
|
||||||
- sends a message across to the remote processor, using the src and dst
|
|
||||||
addresses provided by the user.
|
|
||||||
The caller should specify the channel, the data it wants to send,
|
|
||||||
its length (in bytes), and explicit source and destination addresses.
|
|
||||||
The message will then be sent to the remote processor to which the
|
|
||||||
channel belongs, but the channel's src and dst addresses will be
|
|
||||||
ignored (and the user-provided addresses will be used instead).
|
|
||||||
|
|
||||||
In case there are no TX buffers available, the function will block until
|
|
||||||
one becomes available (i.e. until the remote processor consumes
|
sends a message across to the remote processor, using the src and dst
|
||||||
a tx buffer and puts it back on virtio's used descriptor ring),
|
addresses provided by the user.
|
||||||
or a timeout of 15 seconds elapses. When the latter happens,
|
|
||||||
-ERESTARTSYS is returned.
|
The caller should specify the channel, the data it wants to send,
|
||||||
The function can only be called from a process context (for now).
|
its length (in bytes), and explicit source and destination addresses.
|
||||||
Returns 0 on success and an appropriate error value on failure.
|
The message will then be sent to the remote processor to which the
|
||||||
|
channel belongs, but the channel's src and dst addresses will be
|
||||||
|
ignored (and the user-provided addresses will be used instead).
|
||||||
|
|
||||||
|
In case there are no TX buffers available, the function will block until
|
||||||
|
one becomes available (i.e. until the remote processor consumes
|
||||||
|
a tx buffer and puts it back on virtio's used descriptor ring),
|
||||||
|
or a timeout of 15 seconds elapses. When the latter happens,
|
||||||
|
-ERESTARTSYS is returned.
|
||||||
|
|
||||||
|
The function can only be called from a process context (for now).
|
||||||
|
Returns 0 on success and an appropriate error value on failure.
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
int rpmsg_trysend(struct rpmsg_channel *rpdev, void *data, int len);
|
int rpmsg_trysend(struct rpmsg_channel *rpdev, void *data, int len);
|
||||||
- sends a message across to the remote processor on a given channel.
|
|
||||||
The caller should specify the channel, the data it wants to send,
|
|
||||||
and its length (in bytes). The message will be sent on the specified
|
|
||||||
channel, i.e. its source and destination address fields will be
|
|
||||||
set to the channel's src and dst addresses.
|
|
||||||
|
|
||||||
In case there are no TX buffers available, the function will immediately
|
sends a message across to the remote processor on a given channel.
|
||||||
return -ENOMEM without waiting until one becomes available.
|
The caller should specify the channel, the data it wants to send,
|
||||||
The function can only be called from a process context (for now).
|
and its length (in bytes). The message will be sent on the specified
|
||||||
Returns 0 on success and an appropriate error value on failure.
|
channel, i.e. its source and destination address fields will be
|
||||||
|
set to the channel's src and dst addresses.
|
||||||
|
|
||||||
|
In case there are no TX buffers available, the function will immediately
|
||||||
|
return -ENOMEM without waiting until one becomes available.
|
||||||
|
|
||||||
|
The function can only be called from a process context (for now).
|
||||||
|
Returns 0 on success and an appropriate error value on failure.
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
int rpmsg_trysendto(struct rpmsg_channel *rpdev, void *data, int len, u32 dst)
|
int rpmsg_trysendto(struct rpmsg_channel *rpdev, void *data, int len, u32 dst)
|
||||||
- sends a message across to the remote processor on a given channel,
|
|
||||||
to a destination address provided by the user.
|
|
||||||
The user should specify the channel, the data it wants to send,
|
|
||||||
its length (in bytes), and an explicit destination address.
|
|
||||||
The message will then be sent to the remote processor to which the
|
|
||||||
channel belongs, using the channel's src address, and the user-provided
|
|
||||||
dst address (thus the channel's dst address will be ignored).
|
|
||||||
|
|
||||||
In case there are no TX buffers available, the function will immediately
|
|
||||||
return -ENOMEM without waiting until one becomes available.
|
sends a message across to the remote processor on a given channel,
|
||||||
The function can only be called from a process context (for now).
|
to a destination address provided by the user.
|
||||||
Returns 0 on success and an appropriate error value on failure.
|
|
||||||
|
The user should specify the channel, the data it wants to send,
|
||||||
|
its length (in bytes), and an explicit destination address.
|
||||||
|
|
||||||
|
The message will then be sent to the remote processor to which the
|
||||||
|
channel belongs, using the channel's src address, and the user-provided
|
||||||
|
dst address (thus the channel's dst address will be ignored).
|
||||||
|
|
||||||
|
In case there are no TX buffers available, the function will immediately
|
||||||
|
return -ENOMEM without waiting until one becomes available.
|
||||||
|
|
||||||
|
The function can only be called from a process context (for now).
|
||||||
|
Returns 0 on success and an appropriate error value on failure.
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
int rpmsg_trysend_offchannel(struct rpmsg_channel *rpdev, u32 src, u32 dst,
|
int rpmsg_trysend_offchannel(struct rpmsg_channel *rpdev, u32 src, u32 dst,
|
||||||
void *data, int len);
|
void *data, int len);
|
||||||
- sends a message across to the remote processor, using source and
|
|
||||||
destination addresses provided by the user.
|
|
||||||
The user should specify the channel, the data it wants to send,
|
|
||||||
its length (in bytes), and explicit source and destination addresses.
|
|
||||||
The message will then be sent to the remote processor to which the
|
|
||||||
channel belongs, but the channel's src and dst addresses will be
|
|
||||||
ignored (and the user-provided addresses will be used instead).
|
|
||||||
|
|
||||||
In case there are no TX buffers available, the function will immediately
|
|
||||||
return -ENOMEM without waiting until one becomes available.
|
sends a message across to the remote processor, using source and
|
||||||
The function can only be called from a process context (for now).
|
destination addresses provided by the user.
|
||||||
Returns 0 on success and an appropriate error value on failure.
|
|
||||||
|
The user should specify the channel, the data it wants to send,
|
||||||
|
its length (in bytes), and explicit source and destination addresses.
|
||||||
|
The message will then be sent to the remote processor to which the
|
||||||
|
channel belongs, but the channel's src and dst addresses will be
|
||||||
|
ignored (and the user-provided addresses will be used instead).
|
||||||
|
|
||||||
|
In case there are no TX buffers available, the function will immediately
|
||||||
|
return -ENOMEM without waiting until one becomes available.
|
||||||
|
|
||||||
|
The function can only be called from a process context (for now).
|
||||||
|
Returns 0 on success and an appropriate error value on failure.
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_channel *rpdev,
|
struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_channel *rpdev,
|
||||||
void (*cb)(struct rpmsg_channel *, void *, int, void *, u32),
|
void (*cb)(struct rpmsg_channel *, void *, int, void *, u32),
|
||||||
void *priv, u32 addr);
|
void *priv, u32 addr);
|
||||||
- every rpmsg address in the system is bound to an rx callback (so when
|
|
||||||
inbound messages arrive, they are dispatched by the rpmsg bus using the
|
|
||||||
appropriate callback handler) by means of an rpmsg_endpoint struct.
|
|
||||||
|
|
||||||
This function allows drivers to create such an endpoint, and by that,
|
every rpmsg address in the system is bound to an rx callback (so when
|
||||||
bind a callback, and possibly some private data too, to an rpmsg address
|
inbound messages arrive, they are dispatched by the rpmsg bus using the
|
||||||
(either one that is known in advance, or one that will be dynamically
|
appropriate callback handler) by means of an rpmsg_endpoint struct.
|
||||||
assigned for them).
|
|
||||||
|
|
||||||
Simple rpmsg drivers need not call rpmsg_create_ept, because an endpoint
|
This function allows drivers to create such an endpoint, and by that,
|
||||||
is already created for them when they are probed by the rpmsg bus
|
bind a callback, and possibly some private data too, to an rpmsg address
|
||||||
(using the rx callback they provide when they registered to the rpmsg bus).
|
(either one that is known in advance, or one that will be dynamically
|
||||||
|
assigned for them).
|
||||||
|
|
||||||
So things should just work for simple drivers: they already have an
|
Simple rpmsg drivers need not call rpmsg_create_ept, because an endpoint
|
||||||
endpoint, their rx callback is bound to their rpmsg address, and when
|
is already created for them when they are probed by the rpmsg bus
|
||||||
relevant inbound messages arrive (i.e. messages which their dst address
|
(using the rx callback they provide when they registered to the rpmsg bus).
|
||||||
equals to the src address of their rpmsg channel), the driver's handler
|
|
||||||
is invoked to process it.
|
|
||||||
|
|
||||||
That said, more complicated drivers might do need to allocate
|
So things should just work for simple drivers: they already have an
|
||||||
additional rpmsg addresses, and bind them to different rx callbacks.
|
endpoint, their rx callback is bound to their rpmsg address, and when
|
||||||
To accomplish that, those drivers need to call this function.
|
relevant inbound messages arrive (i.e. messages which their dst address
|
||||||
Drivers should provide their channel (so the new endpoint would bind
|
equals to the src address of their rpmsg channel), the driver's handler
|
||||||
to the same remote processor their channel belongs to), an rx callback
|
is invoked to process it.
|
||||||
function, an optional private data (which is provided back when the
|
|
||||||
rx callback is invoked), and an address they want to bind with the
|
|
||||||
callback. If addr is RPMSG_ADDR_ANY, then rpmsg_create_ept will
|
|
||||||
dynamically assign them an available rpmsg address (drivers should have
|
|
||||||
a very good reason why not to always use RPMSG_ADDR_ANY here).
|
|
||||||
|
|
||||||
Returns a pointer to the endpoint on success, or NULL on error.
|
That said, more complicated drivers might do need to allocate
|
||||||
|
additional rpmsg addresses, and bind them to different rx callbacks.
|
||||||
|
To accomplish that, those drivers need to call this function.
|
||||||
|
Drivers should provide their channel (so the new endpoint would bind
|
||||||
|
to the same remote processor their channel belongs to), an rx callback
|
||||||
|
function, an optional private data (which is provided back when the
|
||||||
|
rx callback is invoked), and an address they want to bind with the
|
||||||
|
callback. If addr is RPMSG_ADDR_ANY, then rpmsg_create_ept will
|
||||||
|
dynamically assign them an available rpmsg address (drivers should have
|
||||||
|
a very good reason why not to always use RPMSG_ADDR_ANY here).
|
||||||
|
|
||||||
|
Returns a pointer to the endpoint on success, or NULL on error.
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
void rpmsg_destroy_ept(struct rpmsg_endpoint *ept);
|
void rpmsg_destroy_ept(struct rpmsg_endpoint *ept);
|
||||||
- destroys an existing rpmsg endpoint. user should provide a pointer
|
|
||||||
to an rpmsg endpoint that was previously created with rpmsg_create_ept().
|
|
||||||
|
destroys an existing rpmsg endpoint. user should provide a pointer
|
||||||
|
to an rpmsg endpoint that was previously created with rpmsg_create_ept().
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
int register_rpmsg_driver(struct rpmsg_driver *rpdrv);
|
int register_rpmsg_driver(struct rpmsg_driver *rpdrv);
|
||||||
- registers an rpmsg driver with the rpmsg bus. user should provide
|
|
||||||
a pointer to an rpmsg_driver struct, which contains the driver's
|
|
||||||
->probe() and ->remove() functions, an rx callback, and an id_table
|
registers an rpmsg driver with the rpmsg bus. user should provide
|
||||||
specifying the names of the channels this driver is interested to
|
a pointer to an rpmsg_driver struct, which contains the driver's
|
||||||
be probed with.
|
->probe() and ->remove() functions, an rx callback, and an id_table
|
||||||
|
specifying the names of the channels this driver is interested to
|
||||||
|
be probed with.
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
void unregister_rpmsg_driver(struct rpmsg_driver *rpdrv);
|
void unregister_rpmsg_driver(struct rpmsg_driver *rpdrv);
|
||||||
- unregisters an rpmsg driver from the rpmsg bus. user should provide
|
|
||||||
a pointer to a previously-registered rpmsg_driver struct.
|
|
||||||
Returns 0 on success, and an appropriate error value on failure.
|
|
||||||
|
|
||||||
|
|
||||||
3. Typical usage
|
unregisters an rpmsg driver from the rpmsg bus. user should provide
|
||||||
|
a pointer to a previously-registered rpmsg_driver struct.
|
||||||
|
Returns 0 on success, and an appropriate error value on failure.
|
||||||
|
|
||||||
|
|
||||||
|
Typical usage
|
||||||
|
=============
|
||||||
|
|
||||||
The following is a simple rpmsg driver, that sends an "hello!" message
|
The following is a simple rpmsg driver, that sends an "hello!" message
|
||||||
on probe(), and whenever it receives an incoming message, it dumps its
|
on probe(), and whenever it receives an incoming message, it dumps its
|
||||||
content to the console.
|
content to the console.
|
||||||
|
|
||||||
#include <linux/kernel.h>
|
::
|
||||||
#include <linux/module.h>
|
|
||||||
#include <linux/rpmsg.h>
|
|
||||||
|
|
||||||
static void rpmsg_sample_cb(struct rpmsg_channel *rpdev, void *data, int len,
|
#include <linux/kernel.h>
|
||||||
|
#include <linux/module.h>
|
||||||
|
#include <linux/rpmsg.h>
|
||||||
|
|
||||||
|
static void rpmsg_sample_cb(struct rpmsg_channel *rpdev, void *data, int len,
|
||||||
void *priv, u32 src)
|
void *priv, u32 src)
|
||||||
{
|
{
|
||||||
print_hex_dump(KERN_INFO, "incoming message:", DUMP_PREFIX_NONE,
|
print_hex_dump(KERN_INFO, "incoming message:", DUMP_PREFIX_NONE,
|
||||||
16, 1, data, len, true);
|
16, 1, data, len, true);
|
||||||
}
|
}
|
||||||
|
|
||||||
static int rpmsg_sample_probe(struct rpmsg_channel *rpdev)
|
static int rpmsg_sample_probe(struct rpmsg_channel *rpdev)
|
||||||
{
|
{
|
||||||
int err;
|
int err;
|
||||||
|
|
||||||
dev_info(&rpdev->dev, "chnl: 0x%x -> 0x%x\n", rpdev->src, rpdev->dst);
|
dev_info(&rpdev->dev, "chnl: 0x%x -> 0x%x\n", rpdev->src, rpdev->dst);
|
||||||
|
|
@ -234,32 +291,35 @@ static int rpmsg_sample_probe(struct rpmsg_channel *rpdev)
|
||||||
}
|
}
|
||||||
|
|
||||||
return 0;
|
return 0;
|
||||||
}
|
}
|
||||||
|
|
||||||
static void rpmsg_sample_remove(struct rpmsg_channel *rpdev)
|
static void rpmsg_sample_remove(struct rpmsg_channel *rpdev)
|
||||||
{
|
{
|
||||||
dev_info(&rpdev->dev, "rpmsg sample client driver is removed\n");
|
dev_info(&rpdev->dev, "rpmsg sample client driver is removed\n");
|
||||||
}
|
}
|
||||||
|
|
||||||
static struct rpmsg_device_id rpmsg_driver_sample_id_table[] = {
|
static struct rpmsg_device_id rpmsg_driver_sample_id_table[] = {
|
||||||
{ .name = "rpmsg-client-sample" },
|
{ .name = "rpmsg-client-sample" },
|
||||||
{ },
|
{ },
|
||||||
};
|
};
|
||||||
MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_sample_id_table);
|
MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_sample_id_table);
|
||||||
|
|
||||||
static struct rpmsg_driver rpmsg_sample_client = {
|
static struct rpmsg_driver rpmsg_sample_client = {
|
||||||
.drv.name = KBUILD_MODNAME,
|
.drv.name = KBUILD_MODNAME,
|
||||||
.id_table = rpmsg_driver_sample_id_table,
|
.id_table = rpmsg_driver_sample_id_table,
|
||||||
.probe = rpmsg_sample_probe,
|
.probe = rpmsg_sample_probe,
|
||||||
.callback = rpmsg_sample_cb,
|
.callback = rpmsg_sample_cb,
|
||||||
.remove = rpmsg_sample_remove,
|
.remove = rpmsg_sample_remove,
|
||||||
};
|
};
|
||||||
module_rpmsg_driver(rpmsg_sample_client);
|
module_rpmsg_driver(rpmsg_sample_client);
|
||||||
|
|
||||||
Note: a similar sample which can be built and loaded can be found
|
.. note::
|
||||||
in samples/rpmsg/.
|
|
||||||
|
|
||||||
4. Allocations of rpmsg channels:
|
a similar sample which can be built and loaded can be found
|
||||||
|
in samples/rpmsg/.
|
||||||
|
|
||||||
|
Allocations of rpmsg channels
|
||||||
|
=============================
|
||||||
|
|
||||||
At this point we only support dynamic allocations of rpmsg channels.
|
At this point we only support dynamic allocations of rpmsg channels.
|
||||||
|
|
||||||
|
|
|
||||||
Loading…
Reference in New Issue