rpmsg: core: Make rpmsg_bus const

Now that the driver core can properly handle constant struct bus_type,
move the rpmsg_bus variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20240204-bus_cleanup-rpmsg-v1-1-1703508c23b7@marliere.net
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

rpmsg: core: Replace deprecated strncpy with strscpy

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

We expect chinfo.name to be NUL-terminated based on its usage with
strncmp():

rpmsg_core.c:
389: if (strncmp(chinfo->name, rpdev->id.name, RPMSG_NAME_SIZE))

Moreover, NUL-padding is not required as chinfo has stack default
initialized all fields to zero:

rpmsg_core.c:
539: struct rpmsg_channel_info chinfo = {};

Considering the above, a suitable replacement is `strscpy` [2] due to
the fact that it guarantees NUL-termination on the destination buffer
without unnecessarily NUL-padding.

Also, favor the more idiomatic strscpy() usage of:
(dest, src, sizeof(dest)).

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20231020-strncpy-drivers-rpmsg-rpmsg_core-c-v1-1-a86b7930c1cf@google.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

rpmsg: core: Add signal API support

Some transports like Glink support the state notifications between
clients using flow control signals similar to serial protocol signals.
Local glink client drivers can send and receive flow control status
to glink clients running on remote processors.

Add APIs to support sending and receiving of flow control status by
rpmsg clients.

Signed-off-by: Deepak Kumar Singh <quic_deesin@quicinc.com>
Signed-off-by: Sarannya S <quic_sarannya@quicinc.com>
Acked-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Link: https://lore.kernel.org/r/1688679698-31274-2-git-send-email-quic_sarannya@quicinc.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

driver core: class: remove module * from class_create()

The module pointer in class_create() never actually did anything, and it
shouldn't have been requred to be set as a parameter even if it did
something. So just remove it and fix up all callers of the function in
the kernel tree at the same time.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Link: https://lore.kernel.org/r/20230313181843.1207845-4-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

driver core: make struct bus_type.uevent() take a const *

The uevent() callback in struct bus_type should not be modifying the
device that is passed into it, so mark it as a const * and propagate the
function signature changes out into all relevant subsystems that use
this callback.

Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230111113018.459199-16-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

rpmsg: Strcpy is not safe, use strscpy_pad() instead

Replace strcpy() with strscpy_pad() for copying the rpmsg
device name in rpmsg_register_device_override().

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Saud Farooqui <farooqui_saud@hotmail.com>
Link: https://lore.kernel.org/r/PA4P189MB14210AA95DCA3715AFA7F4A68BB59@PA4P189MB1421.EURP189.PROD.OUTLOOK.COM
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

rpmsg: Fix possible refcount leak in rpmsg_register_device_override()

rpmsg_register_device_override need to call put_device to free vch when
driver_set_override fails.

Fix this by adding a put_device() to the error path.

Fixes: bb17d110cbf2 ("rpmsg: Fix calling device_lock() on non-initialized device")
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Link: https://lore.kernel.org/r/20220624024120.11576-1-hbh25y@gmail.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

rpmsg: use local 'dev' variable

'&rpdev->dev' is already cached as local variable, so use it to simplify
the code.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220429195946.1061725-3-krzysztof.kozlowski@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

rpmsg: Fix calling device_lock() on non-initialized device

driver_set_override() helper uses device_lock() so it should not be
called before rpmsg_register_device() (which calls device_register()).
Effect can be seen with CONFIG_DEBUG_MUTEXES:

DEBUG_LOCKS_WARN_ON(lock->magic != lock)
WARNING: CPU: 3 PID: 57 at kernel/locking/mutex.c:582 __mutex_lock+0x1ec/0x430
...
Call trace:
__mutex_lock+0x1ec/0x430
mutex_lock_nested+0x44/0x50
driver_set_override+0x124/0x150
qcom_glink_native_probe+0x30c/0x3b0
glink_rpm_probe+0x274/0x350
platform_probe+0x6c/0xe0
really_probe+0x17c/0x3d0
__driver_probe_device+0x114/0x190
driver_probe_device+0x3c/0xf0
...

Refactor the rpmsg_register_device() function to use two-step device
registering (initialization + add) and call driver_set_override() in
proper moment.

This moves the code around, so while at it also NULL-ify the
rpdev->driver_override in error path to be sure it won't be kfree()
second time.

Fixes: 42cd402b8fd4 ("rpmsg: Fix kfree() of static memory on setting driver_override")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20220429195946.1061725-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

rpmsg: Constify local variable in field store macro

Memory pointed by variable 'old' in field store macro is not modified,
so it can be made a pointer to const.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220419113435.246203-12-krzysztof.kozlowski@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

rpmsg: Create the rpmsg class in core instead of in rpmsg char

Migrate the creation of the rpmsg class from the rpmsg_char
to the core that the class is usable by the rpmsg_char and
the future rpmsg_ctrl module.

Suggested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220124102524.295783-3-arnaud.pouliquen@foss.st.com

rpmsg: core: Clean up resources on announce_create failure.

During the rpmsg_dev_probe, if rpdev->ops->announce_create returns an
error, the rpmsg device and default endpoint should be freed before
exiting the function.

Fixes: 5e619b48677c ("rpmsg: Split rpmsg core and virtio backend")
Suggested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20211206190758.10004-1-arnaud.pouliquen@foss.st.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

rpmsg: Fix documentation return formatting

kernel documentation specification:
"The return value, if any, should be described in a dedicated section
named Return."

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Link: https://lore.kernel.org/r/20211108140126.3530-1-arnaud.pouliquen@foss.st.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

rpmsg: core: add API to get MTU

Return the rpmsg buffer MTU for sending message, so rpmsg users
can split a long message in several sub rpmsg buffers.

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Link: https://lore.kernel.org/r/20211015094701.5732-2-arnaud.pouliquen@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

bus: Make remove callback return void

The driver core ignores the return value of this callback because there
is only little it can do when a device disappears.

This is the final bit of a long lasting cleanup quest where several
buses were converted to also return void from their remove callback.
Additionally some resource leaks were fixed that were caused by drivers
returning an error code in the expectation that the driver won't go
away.

With struct bus_type::remove returning void it's prevented that newly
implemented buses return an ignored error code and so don't anticipate
wrong expectations for driver authors.

Reviewed-by: Tom Rix <trix@redhat.com> (For fpga)
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com> (For drivers/s390 and drivers/vfio)
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> (For ARM, Amba and related parts)
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Chen-Yu Tsai <wens@csie.org> (for sunxi-rsb)
Acked-by: Pali Rohár <pali@kernel.org>
Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org> (for media)
Acked-by: Hans de Goede <hdegoede@redhat.com> (For drivers/platform)
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-By: Vinod Koul <vkoul@kernel.org>
Acked-by: Juergen Gross <jgross@suse.com> (For xen)
Acked-by: Lee Jones <lee.jones@linaro.org> (For mfd)
Acked-by: Johannes Thumshirn <jth@kernel.org> (For mcb)
Acked-by: Johan Hovold <johan@kernel.org>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> (For slimbus)
Acked-by: Kirti Wankhede <kwankhede@nvidia.com> (For vfio)
Acked-by: Maximilian Luz <luzmaximilian@gmail.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> (For ulpi and typec)
Acked-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com> (For ipack)
Acked-by: Geoff Levand <geoff@infradead.org> (For ps3)
Acked-by: Yehezkel Bernat <YehezkelShB@gmail.com> (For thunderbolt)
Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> (For intel_th)
Acked-by: Dominik Brodowski <linux@dominikbrodowski.net> (For pcmcia)
Acked-by: Rafael J. Wysocki <rafael@kernel.org> (For ACPI)
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org> (rpmsg and apr)
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> (For intel-ish-hid)
Acked-by: Dan Williams <dan.j.williams@intel.com> (For CXL, DAX, and NVDIMM)
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com> (For isa)
Acked-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (For firewire)
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> (For hid)
Acked-by: Thorsten Scherer <t.scherer@eckelmann.de> (For siox)
Acked-by: Sven Van Asbroeck <TheSven73@gmail.com> (For anybuss)
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> (For MMC)
Acked-by: Wolfram Sang <wsa@kernel.org> # for I2C
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Finn Thain <fthain@linux-m68k.org>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20210713193522.1770306-6-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

rpmsg: core: Add driver_data for rpmsg_device_id

Most device_id structs provide a driver_data field that can be used
by drivers to associate data more easily for a particular device ID.
Add the same for the rpmsg_device_id.

Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

rpmsg: core: Add channel creation internal API

Add the channel creation API as a first step to be able to define the
name service announcement as a rpmsg driver independent from the RPMsg
virtio bus.

Tested-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Link: https://lore.kernel.org/r/20201120214245.172963-6-mathieu.poirier@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Guard against null endpoint ops in destroy

In RPMSG GLINK the chrdev device will allocate an ept as part of the
rpdev creation. This device will not register endpoint ops even though
it has an allocated ept. Protect against the case where the device is
being destroyed.

Signed-off-by: Chris Lew <clew@codeaurora.org>
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org>
Link: https://lore.kernel.org/r/1593017121-7953-3-git-send-email-deesin@codeaurora.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: fix a comment typo for rpmsg_device_match()

Should be 'a' rather than 'an'.

Signed-off-by: WANG Wenhu <wenhu.wang@vivo.com>
Link: https://lore.kernel.org/r/20200313165049.62907-1-wenhu.wang@vivo.com
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: core: fix comments

Minor typos, grammar and copy/paste issues. Fix for consistency. No
functional or semantic change.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: core: Make remove handler for rpmsg driver optional.

Most other bus (for example, SPI, i2c) have the remove handler for
driver optional. Make remove handler for rpmsg driver optional too.

Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: core: add support to power domains for devices

Some of the rpmsg devices need to switch on power domains to communicate
with remote processor. For example on Qualcomm DB820c platform LPASS
power domain needs to switched on for any kind of audio services.
This patch adds the missing power domain support in rpmsg core.

Without this patch attempting to play audio via QDSP on DB820c would
reboot the system.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Switch to SPDX license identifier

Use the appropriate SPDX license identifier in the rpmsg core
source files and drop the previous boilerplate license text.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Add driver_override device attribute for rpmsg_device

This patch adds "driver_override" device attribute for rpmsg_device which
will allow users to explicitly specify the rpmsg_driver to be used via
sysfs entry.

The "driver_override" device attribute implemented here is very similar
to "driver_override" implemented for platform, pci, and amba bus types.

One important use-case of "driver_override" device attribute is to force
use of rpmsg_chrdev driver for certain rpmsg_device instances.

Signed-off-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Only invoke announce_create for rpdev with endpoints

For special rpmsg devices without a primary endpoint there is nothing to
announce so don't call the backend announce create function if we didn't
create an endpoint.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

the rest of drivers/*: annotate ->poll() instances

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

rpmsg: Make modalias work for DeviceTree based devices

When rpmsg devices are expected to be matched based on their compatible
the modalias should reflect this, so that module autoloading has a
chance to match and load the appropriate module.

Tested-by: Rob Clark <robdclark@gmail.com>
Reported-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Don't overwrite release op of rpdev

b0b03b811963 ("rpmsg: Release rpmsg devices in backends") attempted to
correct the ownership of freeing rpmsg device memory. But the patch
is not complete, in that the rpmsg core will overwrite the release op as
the device is being registered.

Fixes: b0b03b811963 ("rpmsg: Release rpmsg devices in backends")
Reported-by: Henri Roosen <henri.roosen@ginzinger.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: use dev_groups and not dev_attrs for bus_type

The dev_attrs field has long been "depreciated" and is finally being
removed, so move the driver to use the "correct" dev_groups field
instead for struct bus_type.

Cc: Ohad Ben-Cohen <ohad@wizery.com>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: <linux-remoteproc@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

rpmsg: rpmsg_create_ept() returns NULL on error

The parameter validation incorrectly returned an ERR_PTR(), which is not
handled by the callers to rpmsg_create_ept(), per the definition NULL
should be returned.

Fixes: 93e9324431c9 ("rpmsg: Handle invalid parameters in public API")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Introduce "poll" to endpoint ops

This allows rpmsg backends to implement polling of the outgoing buffer,
which provides poll support to user space when using the rpmsg character
device.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: virtio_rpmsg_bus: fix channel creation

Since commit 4dffed5b3ac796b ("rpmsg: Name rpmsg devices based on
channel id"), it is no more possible for a firmware to register twice
a service (on different endpoints). rpmsg_register_device function
is failing when calling device_add for the second time as second
device has the same name as first one already register.
It is because name is based only on service name and so is not more
unique. Previously name was unique thanks to the use of rpmsg_dev_index.

This patch adds destination and source endpoint numbers device name to
create an unique identifier.

Fixes: 4dffed5b3ac7 ("rpmsg: Name rpmsg devices based on channel id")
Acked-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Loic Pallardy <loic.pallardy@st.com>
[bjorn: flipped name and address in device name]
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Handle invalid parameters in public API

There are two cases of possible uninitialized pointer usage in the API,
either the parameters themselves are invalid or we're trying to jump to
functions not required to be implemented by all backends.

Suggested-by: Loic Pallardy <loic.pallardy@st.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Support drivers without primary endpoint

Some types of rpmsg drivers does not have a primary endpoint to tie
their existence upon, but wishes to create and destroy endpoints
dynamically, e.g. based on user interactions.

Allow rpmsg drivers to omit a driver callback to signal this case and
make the probe path not create a primary endpoint in this case.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Introduce a driver override mechanism

Similar to other subsystems it's useful to provide a mechanism to force
a specific driver match on a device, so introduce this.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Hide rpmsg indirection tables

Move the device and endpoint indirection tables to the rpmsg internal
header file, to hide them from the public API.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Split rpmsg core and virtio backend

Extract the generic rpmsg core functionality from the virtio rpmsg
implementation, splitting the implementation in a rpmsg core and a
virtio backend.

Based on initial work by Sricharan R <sricharan@codeaurora.org>

Cc: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Move helper for finding rpmsg devices to core

Extract and move the helper function for finding rpmsg child devices to
the core.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Move endpoint related interface to rpmsg core

Move the rpmsg_send() and rpmsg_destroy_ept() interface to the rpmsg
core, so that we eventually can hide the rpmsg_endpoint ops from the
public API.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Move rpmsg_device API to new file

Extract the now indirect rpmsg_create_ept() interface to a separate
file and start building up a rpmsg core.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>