firmware: arm_scmi: Populate fast channel rate_limit

Arm SCMI spec. v3.2, s4.5.3.12 PERFORMANCE_DESCRIBE_FASTCHANNEL
defines a per-domain rate_limit for performance requests:
"""
Rate Limit in microseconds, indicating the minimum time
required between successive requests. A value of 0
indicates that this field is not applicable or supported
on the platform.
""""
The field is first defined in SCMI v2.0.

Add support to fetch this value and advertise it through
a fast_switch_rate_limit() callback.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

firmware: arm_scmi: Add support for v3.2 NEGOTIATE_PROTOCOL_VERSION

Freshly introduced NEGOTIATE_PROTOCOL_VERSION allows the agent to ascertain
upfront if a specific protocol(usually older) version is supported by the
platform.

It is used by the agent in case the platform has advertised the support of
a newer protocol version than the latest version supported by the agent,
since backward compatibility cannot be automatically assumed.

Emit a warning about possible incompatibility when negotiation was not
possible or just print the successfully negotiated protocol.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20240214183006.3403207-3-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add a common helper to check if a message is supported

A common helper is provided to check if a specific protocol message is
supported or not.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20240212123233.1230090-3-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/86165c8ccd0bb47000a29e711102795b36c8df41.1703693980.git.u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: arm_scmi: Add protocol versioning checks

Platform and agent supported protocols versions do not necessarily match.

When talking to an older SCMI platform, supporting only older protocol
versions, the kernel SCMI agent will downgrade the version of the used
protocol to match the platform and avoid compatibility issues.

In the case where the kernel/OSPM agent happens to communicate with a
newer platform which can support newer protocol versions unknown to
the agent, and potentially backward incompatible, the agent currently
carries on, silently, in a best-effort approach.

Note that the SCMI specification doesn't provide means to explicitly
detect the protocol versions used by the agents, neither it is required
to support multiple, older, protocol versions.

Add an explicit protocol version check to let the agent detect when this
version mismatch happens and warn the user about this condition.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20231201135858.2367651-1-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add optional flags to extended names helper

Some recently added SCMI protocols needs an additional flags parameter to
be able to properly configure the command used to query the extended name
of a resource.

Modify extended_name_get helper accordingly.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20231114145449.3136412-1-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add qcom smc/hvc transport support

This change adds the support for SCMI message exchange on Qualcomm
virtual platforms.

The hypervisor associates an object-id also known as capability-id
with each smc/hvc doorbell object. The capability-id is used to
identify the doorbell from the VM's capability namespace, similar
to a file-descriptor.

The hypervisor, in addition to the function-id, expects the capability-id
to be passed in x1 register when SMC/HVC call is invoked.

The capability-id is allocated by the hypervisor on bootup and is stored in
the shmem region by the firmware before starting Linux.

Signed-off-by: Nikunj Kela <quic_nkela@quicinc.com>
Reviewed-by: Brian Masney <bmasney@redhat.com>
Link: https://lore.kernel.org/r/20231009191437.27926-3-quic_nkela@quicinc.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: Explicitly include correct DT includes

The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.

Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20230803-dt-header-cleanups-for-soc-v2-17-d8de2cc88bff@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

firmware: arm_scmi: Augment SMC/HVC to allow optional parameters

This change adds support for passing shmem channel address as parameters
in smc/hvc call. The address is split into 4KB-page and offset.
This is useful when multiple scmi instances are using same smc-id
and firmware needs to distinguish among the instances.

Signed-off-by: Nikunj Kela <quic_nkela@quicinc.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230506182428.25343-3-quic_nkela@quicinc.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix xfers allocation on Rx channel

Two distinct pools of xfer descriptors are allocated at initialization
time: one (Tx) used to provide xfers to track commands and their replies
(or delayed replies) and another (Rx) to pick xfers from to be used for
processing notifications.

Such pools, though, are allocated globally to be used by the whole SCMI
instance, they are not allocated per-channel and as such the allocation of
notifications xfers cannot be simply skipped if no Rx channel was found for
the base protocol common channel, because there could be defined more
optional per-protocol dedicated channels that instead support Rx channels.

Change the conditional check to skip allocation for the notification pool
only if no Rx channel has been detected on any per-channel protocol at all.

Fixes: 4ebd8f6dea81 ("firmware: arm_scmi: Add receive buffer support for notifications")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20230326203449.3492948-1-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Use the bitmap API to allocate bitmaps

Use devm_bitmap_zalloc() instead of hand-writing them.

It is less verbose and it improves the semantic.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/c073b1607ada34d5bde6ce1009179cf15bbf0da3.1657308593.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix raw coexistence mode behaviour on failure path

When SCMI raw coexistence mode is enabled make the core stack probe
successfully even when the initial base protocol exchanges with the
platform/server failed.

This behaviour enables the system to boot with a broken regular SCMI
stack but with a fully functional and accessible SCMI raw debugfs
interface that can be used to further debug the issue.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20230223152330.2707260-1-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Clean up a return statement in scmi_probe

The comments say "enabled" where "disabled" is intended. Also it's
cleaner to return zero explicitly instead of ret.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/r/Y86im5M49p3ePGxj@kili
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add per-channel raw injection support

On a system configured with multiple transport channels, expose a few
additional debugfs per-channel entries to allow a user to explicitly select
which transport channel to use for the SCMI message injection.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-18-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add the raw mode co-existence support

When the raw support is enabled and configured in co-existence mode the
normal SCMI drivers are allowed to register with the SCMI core and
operate as usual alongside the raw operations.

SCMI normal and raw messages will be kept segregated from each other,
but only at the transaction level. Any further possible interference at
the protocol layer will have instead to be handled by the user to attain
reliable results while using the raw transactions.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-17-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Call raw mode hooks from the core stack

Add a few call sites where, if SCMI raw mode access had been enabled in
Kconfig, the needed SCMI raw initialization and hooks are called.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-16-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add core raw transmission support

Add SCMI raw mode support which exposes a userspace interface to allow for
bare SCMI command injection and snooping from userspace.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-13-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Populate a common SCMI debugfs root

Create a common SCMI debugfs root directory and populate it with some
common SCMI data for each discovered SCMI platform instance if SCMI
debugfs is needed by any configured SCMI facility.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-11-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

include: trace: Add platform and channel instance references

Add the channel and platform instance indentifier to SCMI message dump
traces in order to easily associate message flows to specific transport
channels.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-9-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add internal platform/channel identifiers

Add a couple of unique identifiers to channel and platform instance
descriptors in order to emit more descriptive message dump traces.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-8-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Move errors defs and code to common.h

Move SCMI error codes definitions and helper to the common.h header
together with the delayed response timeout define.

No functional change.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-7-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add xfer helpers to provide raw access

Add a few SCMI helpers useful to implement SCMI raw access support.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-6-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Refactor scmi_wait_for_message_response

Refactor scmi_wait_for_message_response() to use a internal helper to
carry out its main duties; while doing that make it accept directly an
scmi_desc parameter to interact with the configured transport.

No functional change.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-4-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Refactor polling helpers

Refactor polling helpers to receive scmi_desc directly as a parameter and
move all of them to common.h.

No functional change.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-3-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Refactor xfer in-flight registration routines

Move the whole xfer in-flight registration process out of scmi_xfer_get
and while at that, split the sequence number selection steps from the
in-flight registration procedure itself.

No functional change.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-2-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Split bus and driver into distinct modules

Make the SCMI bus on its own as a distinct module initialized at
subsys_initcall level when builtin.

Keep the SCMI driver core stack, together with any configured transport,
in a different module initialized as module_init level.

SCMI drivers initialization remain unchanged at module_init level.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221222185049.737625-10-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Introduce a new lifecycle for protocol devices

Protocol devices are created or destroyed depending on the related device
request/unrequest events emitted on the scmi_requested_devices_nh
notification chain by the SCMI bus and served in the driver by the
scmi_device_request_notifier.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221222185049.737625-9-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Refactor device create/destroy helpers

Refactor SCMI device create/destroy helpers: it is now possible to ask
for the creation of all the currently requested devices for a whole
protocol, not only for the creation of a single well-defined device.

While at that, re-instate uniqueness checks on the creation of SCMI
SystemPower devices.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221222185049.737625-8-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Move handle get/set helpers

Move handle get/set helpers definitions into driver.c and invoke them
through the bus notifier helper.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221222185049.737625-7-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Refactor protocol device creation

Move protocol device request helpers from driver.c compilation unit to
bus.c, so reducing the cross interactions between driver.c and bus.c.

Get rid of old protocol device creation process as a whole from driver.c
and remove also stale SCMI system power unicity checks.

While at that make such helpers call into scmi_requested_devices_nh
notification chain.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221222185049.737625-6-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add common notifier helpers

Add a pair of notifier chains and generic empty notifier callbacks.
Currently they are still unused but they will be used to act properly
on device request and creation events.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221222185049.737625-5-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Move protocol registration helpers

Move protocol registration helpers and logic out of bus.c compilation
unit into driver.c.

No functional change.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221222185049.737625-4-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Use dedicated devices to initialize channels

Refactor channels initialization to use dedicated transport devices
instead of using devices borrowed from the SCMI drivers.

Initialize all channels, as described in the device tree, upfront during
SCMI core stack probe phase and free all of them, including the underlying
devices, when the SCMI core is removed.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221222185049.737625-3-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Simplify chan_available transport operation

SCMI transport operation .chan_available determines in a transport
specific way if an SCMI channel is still available and to be configured.
Such information is derived by analyzing bits of device node in a
transport specific way, all it needs is a device node to operate up on,
not necessarily a full blown device.

Simplify the helper to receive in input a reference to a device_node
instead of a device carrying a pointer to such device_node.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221222185049.737625-2-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Clear stale xfer->hdr.status

Stale error status reported from a previous message transaction must be
cleared before starting a new transaction to avoid being confusingly
reported in the following SCMI message dump traces.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221222183823.518856-2-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Make Rx chan_setup fail on memory errors

SCMI Rx channels are optional and they can fail to be setup when not
present but anyway channels setup routines must bail-out on memory errors.

Make channels setup, and related probing, fail when memory errors are
reported on Rx channels.

Fixes: 5c8a47a5a91d ("firmware: arm_scmi: Make scmi core independent of the transport type")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221028140833.280091-4-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Make tx_prepare time out eventually

SCMI transports based on shared memory, at start of transmissions, have
to wait for the shared Tx channel area to be eventually freed by the
SCMI platform before accessing the channel. In fact the channel is owned
by the SCMI platform until marked as free by the platform itself and,
as such, cannot be used by the agent until relinquished.

As a consequence a badly misbehaving SCMI platform firmware could lock
the channel indefinitely and make the kernel side SCMI stack loop
forever waiting for such channel to be freed, possibly hanging the
whole boot sequence.

Add a timeout to the existent Tx waiting spin-loop so that, when the
system ends up in this situation, the SCMI stack can at least bail-out,
nosily warn the user, and abort the transmission.

Reported-by: YaxiongTian <iambestgod@outlook.com>
Suggested-by: YaxiongTian <iambestgod@outlook.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Etienne Carriere <etienne.carriere@linaro.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221028140833.280091-3-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Suppress the driver's bind attributes

Suppress the capability to unbind the core SCMI driver since all the
SCMI stack protocol drivers depend on it.

Fixes: aa4f886f3893 ("firmware: arm_scmi: add basic driver infrastructure for SCMI")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221028140833.280091-2-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Cleanup the core driver removal callback

Platform drivers .remove callbacks are not supposed to fail and report
errors. Such errors are indeed ignored by the core platform drivers
and the driver unbind process is anyway completed.

The SCMI core platform driver as it is now, instead, bails out reporting
an error in case of an explicit unbind request.

Fix the removal path by adding proper device links between the core SCMI
device and the SCMI protocol devices so that a full SCMI stack unbind is
triggered when the core driver is removed. The remove process does not
bail out anymore on the anomalous conditions triggered by an explicit
unbind but the user is still warned.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20221028140833.280091-1-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Generalize the fast channel support

Generalize existing fast channel support used in the perf protocol and
make it available to possibly any protocol refactoring the common code
into a couple of new scmi_proto_helpers_ops routines.

Make perf protocol use this new infrastructure.

No functional change.

Link: https://lore.kernel.org/r/20220704102241.2988447-4-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add SCMI v3.1 powercap protocol basic support

Add support for SCMI v3.1 powercap protocol, with the exception of powercap
fast channels, exposing all the new related powercap protocol operations as
usual in include/linux/scmi_protocol.h.

Link: https://lore.kernel.org/r/20220704102241.2988447-3-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add devm_protocol_acquire helper

Add a method to get hold of a protocol, causing it to be initialized and
its resource accounting updated, without getting access to its operations
and handle.

Some protocols, like SCMI SystemPower, do not expose any protocol ops to
the kernel OSPM agent but still need to be at least initialized. This
helper avoids the need to invoke a full devm_get_protocol() only to get
the protocol initialized while throwing away unused the protocol ops and
handle.

Link: https://lore.kernel.org/r/20220704101933.2981635-4-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Support only one single system power device

In order to minimize SCMI platform fw-side complexity, only one single SCMI
platform should be in charge of SCMI SystemPower protocol communications
with the OSPM. Enforce the existence of one single unique device associated
with SystemPower protocol across any possible number of SCMI platforms, and
warn if a system tries to register different SystemPower devices from
multiple platforms.

Link: https://lore.kernel.org/r/20220704101933.2981635-2-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Use new SCMI full message tracing

Add full message tracing for all transmitted and successfully received SCMI
commands, replies and notifications.

Link: https://lore.kernel.org/r/20220630173135.2086631-3-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Relax CLOCK_DESCRIBE_RATES out-of-spec checks

A reply to CLOCK_DESCRIBE_RATES issued against a non rate-discrete clock
should be composed of a triplet of rates descriptors (min/max/step)
returned all in one reply message.

This is not always the case when dealing with some SCMI server deployed in
the wild: relax such constraint while maintaining memory safety by checking
carefully the returned payload size.

While at that cleanup a stale debug printout.

Link: https://lore.kernel.org/r/20220616170347.2800771-1-cristian.marussi@arm.com
Fixes: 7bc7caafe6b1 ("firmware: arm_scmi: Use common iterators in the clock protocol")
Tested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix late checks on pointer dereference

A few dereferences could happen before the iterator pointer argument was
checked for NULL, causing the following smatch warnings:

drivers/firmware/arm_scmi/driver.c:1214 scmi_iterator_run() warn: variable
dereferenced before check 'i' (see line 1210)

Fix by moving the checks early and dropping some unneeded local references.

No functional change.

Link: https://lore.kernel.org/r/20220503121047.3590340-1-cristian.marussi@arm.com
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add iterators for multi-part commands

SCMI specification defines some commands as optionally issued over multiple
messages in order to overcome possible limitations in payload size enforced
by the configured underlyinng transport.

Introduce some common protocol helpers to provide a unified solution for
issuing such SCMI multi-part commands.

Link: https://lore.kernel.org/r/20220330150551.2573938-14-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Introduce a common SCMI v3.1 .extended_name_get helper

Introduce a new set of common protocol operations bound to the protocol
handle structure so that can be invoked by the protocol implementation code
even when protocols are built as distinct loadable kernel module without
the need of exporting new symbols, like already done with scmi_xfer_ops.

Add at first, as new common protocol helper, an .extended_name_get helper
which will ease implementation and will avoid code duplication when adding
new SCMIv3.1 per-protocol _NAME_GET commands.

Link: https://lore.kernel.org/r/20220330150551.2573938-11-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Dynamically allocate implemented protocols array

Move away from a statically allocated array for holding the current set of
protocols implemented by the platform in favour of allocating it
dynamically based on the number of protocols effectively advertised by the
platform via BASE protocol exchanges.

While at that, rectify the BASE_DISCOVER_LIST_PROTOCOLS loop iterations to
terminate only when a number of protocols equal to the advertised ones has
been received, instead of looping till the platform returns no more
protocols descriptors. This new behaviour is better compliant with the
specification and it has been tested to work equally well against an SCMI
stack running on top of an official SCP firmware on a JUNO board.

Link: https://lore.kernel.org/r/20220330150551.2573938-6-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Remove clear channel call on the TX channel

On SCMI transports whose channels are based on a shared resource the TX
channel area has to be acquired by the agent before placing the desired
command into the channel and it will be then relinquished by the platform
once the related reply has been made available into the channel.
On an RX channel the logic is reversed with the platform acquiring the
channel area and the agent reliquishing it once done by calling the
scmi_clear_channel() helper.

As a consequence, even in case of error, the agent must never try to clear
a TX channel from its side: restrict the existing clear channel call on the
the reply path only to delayed responses since they are indeed coming from
the RX channel.

Link: https://lore.kernel.org/r/20220224152404.12877-1-cristian.marussi@arm.com
Fixes: e9b21c96181c ("firmware: arm_scmi: Make .clear_channel optional")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Support optional system wide atomic-threshold-us

An SCMI agent can be configured system-wide with a well-defined atomic
threshold: only SCMI synchronous command whose latency has been advertised
by the SCMI platform to be lower or equal to this configured threshold will
be considered for atomic operations, when requested and if supported by the
underlying transport at all.

Link: https://lore.kernel.org/r/20220217131234.50328-6-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add atomic mode support to virtio transport

Add support for .mark_txdone and .poll_done transport operations to SCMI
VirtIO transport as pre-requisites to enable atomic operations.

Add a Kernel configuration option to enable SCMI VirtIO transport polling
and atomic mode for selected SCMI transactions while leaving it default
disabled.

Link: https://lore.kernel.org/r/20220217131234.50328-4-cristian.marussi@arm.com
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Igor Skalkin <igor.skalkin@opensynergy.com>
Cc: Peter Hilber <peter.hilber@opensynergy.com>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add new parameter to mark_txdone

Add a new xfer parameter to mark_txdone transport operation which enables
the SCMI core to optionally pass back into the transport layer a reference
to the xfer descriptor that is being handled.

Link: https://lore.kernel.org/r/20211220195646.44498-9-cristian.marussi@arm.com
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add support for atomic transports

An SCMI transport can be configured as .atomic_enabled in order to signal
to the SCMI core that all its TX path is executed in atomic context and
that, when requested, polling mode should be used while waiting for command
responses.

When a specific platform configuration had properly configured such a
transport as .atomic_enabled, the SCMI core will also take care not to
sleep in the corresponding RX path while waiting for a response if that
specific command transaction was requested as atomic using polling mode.

Asynchronous commands should not be used in an atomic context and so a
warning is emitted if polling was requested for an asynchronous command.

Add also a method to check, from the SCMI drivers, if the underlying SCMI
transport is currently configured to support atomic transactions: this will
be used by upper layers to determine if atomic requests can be supported at
all on this SCMI instance.

Link: https://lore.kernel.org/r/20211220195646.44498-7-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add sync_cmds_completed_on_ret transport flag

Add a flag to let the transport signal to the core if its handling of sync
command implies that, after .send_message has returned successfully, the
requested command can be assumed to be fully and completely executed on
SCMI platform side so that any possible response value is already
immediately available to be retrieved by a .fetch_response: in other words
the polling phase can be skipped in such a case and the response values
accessed straight away.

Note that all of the above applies only when polling mode of operation was
selected by the core: if instead a completion IRQ was found to be available
the normal response processing path based on completions will still be
followed.

Link: https://lore.kernel.org/r/20211220195646.44498-4-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add configurable polling mode for transports

SCMI communications along TX channels can optionally be provided of a
completion interrupt; when such interrupt is not available, command
transactions should rely on polling, where the SCMI core takes care to
repeatedly evaluate the transport-specific .poll_done() function, if
available, to determine if and when a request was fully completed or
timed out.

Such mechanism is already present and working on a single transfer base:
SCMI protocols can indeed enable hdr.poll_completion on specific commands
ahead of each transfer and cause that transaction to be handled with
polling.

Introduce a couple of flags to be able to enforce such polling behaviour
globally at will:

- scmi_desc.force_polling: to statically switch the whole transport to
polling mode.

- scmi_chan_info.no_completion_irq: to switch a single channel dynamically
to polling mode if, at runtime, is determined that no completion
interrupt was available for such channel.

Link: https://lore.kernel.org/r/20211220195646.44498-2-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Use new trace event scmi_xfer_response_wait

Use new trace event to mark start of waiting for response section.

Link: https://lore.kernel.org/r/20211129191156.29322-6-cristian.marussi@arm.com
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Refactor message response path

Refactor code path waiting for message responses into a dedicated helper
function.

No functional change.

Link: https://lore.kernel.org/r/20211129191156.29322-4-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Set polling timeout to max_rx_timeout_ms

Use transport specific transmission timeout (max_rx_timeout_ms) also for
polling transactions.

Initially when polling mode was added, it was intended to be used only
in scheduler context and hence the choice of 100us for the polling timeout.
However the only user for that was dropped for other SCMI concurrency
issues, so it shouldn't cause any issue to increase this timeout value now.

Link: https://lore.kernel.org/r/20211129191156.29322-3-cristian.marussi@arm.com
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
[sudeep.holla: Updated commit message with historical facts about 100us timeout]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Perform earlier cinfo lookup call in do_xfer

Lookup cinfo data early in do_xfer so as to avoid any further init work
on xfer structure in case of error.

No functional change.

Link: https://lore.kernel.org/r/20211129191156.29322-2-cristian.marussi@arm.com
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add optee transport

Add a new transport channel to the SCMI firmware interface driver for
SCMI message exchange based on optee transport channel. The optee
transport is realized by connecting and invoking OP-TEE SCMI service
interface PTA.

Optee transport support (CONFIG_ARM_SCMI_TRANSPORT_OPTEE) is default
enabled when optee driver (CONFIG_OPTEE) is enabled. Effective optee
transport is setup upon OP-TEE SCMI service discovery at optee
device initialization. For this SCMI UUID is registered to the optee
bus for probing. This is done from the link_supplier operator of the
SCMI optee transport.

The optee transport can use a statically defined shared memory in
which case SCMI device tree node defines it using an "arm,scmi-shmem"
compatible phandle through property shmem. Alternatively, optee transport
allocates the shared memory buffer from the optee driver when no shmem
property is defined.

The protocol used to exchange SCMI message over that shared memory is
negotiated between optee transport driver and the OP-TEE service through
capabilities exchange.

OP-TEE SCMI service is integrated in OP-TEE since its release tag 3.13.0.
The service interface is published in [1].

Link: [1] https://github.com/OP-TEE/optee_os/blob/3.13.0/lib/libutee/include/pta_scmi_client.h
Link: https://lore.kernel.org/r/20211028140009.23331-2-etienne.carriere@linaro.org
Cc: Cristian Marussi <cristian.marussi@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Remove space in MODULE_ALIAS name

modprobe can't handle spaces in aliases. Get rid of it to fix the issue.

Link: https://lore.kernel.org/r/20220211102704.128354-1-sudeep.holla@arm.com
Fixes: aa4f886f3893 ("firmware: arm_scmi: add basic driver infrastructure for SCMI")
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Alyssa Ross <hi@alyssa.is>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Use WARN_ON() to check configured transports

Use a WARN_ON() when SCMI stack is loaded to check the consistency of
configured SCMI transports instead of the current compile-time check
BUILD_BUG_ON() to avoid breaking bot-builds on random bad configs.

Bail-out early and noisy during SCMI stack initialization if no transport
was enabled in configuration since SCMI cannot work without at least one
enabled transport and such constraint cannot be enforced in Kconfig due to
circular dependency issues.

Link: https://lore.kernel.org/r/20210809092245.8730-1-cristian.marussi@arm.com
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Free mailbox channels if probe fails

Mailbox channels for the base protocol are setup during probe.
There can be a scenario where probe fails to acquire the base
protocol due to a timeout leading to cleaning up of all device
managed memory including the scmi_mailbox structure setup during
mailbox_chan_setup function.

| arm-scmi soc:qcom,scmi: timed out in resp(caller: version_get+0x84/0x140)
| arm-scmi soc:qcom,scmi: unable to communicate with SCMI
| arm-scmi: probe of soc:qcom,scmi failed with error -110

Now when a message arrives at cpu slightly after the timeout, the mailbox
controller will try to call the rx_callback of the client and might end
up accessing freed memory.

| rx_callback+0x24/0x160
| mbox_chan_received_data+0x44/0x94
| __handle_irq_event_percpu+0xd4/0x240

This patch frees the mailbox channels setup during probe and adds some more
error handling in case the probe fails.

Link: https://lore.kernel.org/r/1628111999-21595-1-git-send-email-rishabhb@codeaurora.org
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add virtio transport

This transport enables communications with an SCMI platform through virtio;
the SCMI platform will be represented by a virtio device.

Implement an SCMI virtio driver according to the virtio SCMI device spec
[1]. Virtio device id 32 has been reserved for the SCMI device [2].

The virtio transport has one Tx channel (virtio cmdq, A2P channel) and
at most one Rx channel (virtio eventq, P2A channel).

The following feature bit defined in [1] is not implemented:
VIRTIO_SCMI_F_SHARED_MEMORY.

The number of messages which can be pending simultaneously is restricted
according to the virtqueue capacity negotiated at probing time.

As soon as Rx channel message buffers are allocated or have been read
out by the arm-scmi driver, feed them back to the virtio device.

Since some virtio devices may not have the short response time exhibited
by SCMI platforms using other transports, set a generous response
timeout.

SCMI polling mode is not supported by this virtio transport since deemed
meaningless: polling mode operation is offered by the SCMI core to those
transports that could not provide a completion interrupt on the TX path,
which is never the case for virtio whose core callbacks can easily call
into core scmi_rx_callback upon messages reception.

[1] https://github.com/oasis-tcs/virtio-spec/blob/master/virtio-scmi.tex
[2] https://www.oasis-open.org/committees/ballot.php?id=3496

Link: https://lore.kernel.org/r/20210803131024.40280-16-cristian.marussi@arm.com
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Co-developed-by: Peter Hilber <peter.hilber@opensynergy.com>
Co-developed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Igor Skalkin <igor.skalkin@opensynergy.com>
[ Peter: Adapted patch for submission to upstream. ]
Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
[ Cristian: simplified driver logic, changed link_supplier and channel
available/setup logic, removed dummy callbacks ]
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add priv parameter to scmi_rx_callback

Add a new opaque void *priv parameter to scmi_rx_callback which can be
optionally provided by the transport layer when invoking scmi_rx_callback
and that will be passed back to the transport layer in xfer->priv.

This can be used by transports that needs to keep track of their specific
data structures together with the valid xfers.

Link: https://lore.kernel.org/r/20210803131024.40280-15-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add optional link_supplier() transport op

Some transports are also effectively registered with other kernel subsystem
in order to be properly probed and initialized; as a consequence such kind
of transports, and their related devices, might still not have been probed
and initialized at the time the main SCMI core driver is probed.

Add an optional .link_supplier() transport operation which can be used by
the core SCMI stack to dynamically check if the transport is ready and
dynamically link its device to the SCMI platform instance device.

Link: https://lore.kernel.org/r/20210803131024.40280-13-cristian.marussi@arm.com
Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
[ Cristian: reworded commit message ]
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add method to override max message number

The maximum number of simultaneously pending messages is a transport
specific quantity that is usually described statically in struct scmi_desc.

Some transports, though, can calculate such number only at run-time after
some initial transport specific setup and probing is completed; moreover
the resulting max message numbers could also be different between rx and
tx channels.

Add an optional get_max_msg() operation so that a transport can report more
accurate max message numbers for each channel type.

The value in scmi_desc.max_msg is still used as default when transport does
not provide any get_max_msg() method.

Link: https://lore.kernel.org/r/20210803131024.40280-11-cristian.marussi@arm.com
Co-developed-by: Peter Hilber <peter.hilber@opensynergy.com>
Co-developed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Igor Skalkin <igor.skalkin@opensynergy.com>
[ Peter: Adapted patch for submission to upstream. ]
Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
[ Cristian: refactored how get_max_msg() is used to minimize core changes ]
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Make SCMI transports configurable

Add configuration options to be able to select which SCMI transports have
to be compiled into the SCMI stack.

Mailbox and SMC are by default enabled if their related dependencies are
satisfied.

While doing that move all SCMI related config options in their own
dedicated submenu.

Link: https://lore.kernel.org/r/20210803131024.40280-9-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Make polling mode optional

Add a check for the presence of .poll_done transport operation so that
transports that do not need to support polling mode have no need to provide
a dummy .poll_done callback either and polling mode can be disabled in the
SCMI core for that tranport.

Link: https://lore.kernel.org/r/20210803131024.40280-8-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Make .clear_channel optional

Make transport operation .clear_channel optional since some transports
do not need it and so avoid to have them implement dummy callbacks.

Link: https://lore.kernel.org/r/20210803131024.40280-7-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Handle concurrent and out-of-order messages

Even though in case of asynchronous commands an SCMI platform is
constrained to emit the delayed response message only after the related
message response has been sent, the configured underlying transport could
still deliver such messages together or in inverted order, causing races
due to the concurrent or out-of-order access to the underlying xfer.

Introduce a mechanism to grant exclusive access to an xfer in order to
properly serialize concurrent accesses to the same xfer originating from
multiple correlated messages.

Add additional state information to xfer descriptors so as to be able to
identify out-of-order message deliveries and act accordingly:

- when a delayed response is expected but delivered before the related
response, the synchronous response is considered as successfully
received and the delayed response processing is carried on as usual.

- when/if the missing synchronous response is subsequently received, it
is discarded as not congruent with the current state of the xfer, or
simply, because the xfer has been already released and so, now, the
monotonically increasing sequence number carried by the late response
is stale.

Link: https://lore.kernel.org/r/20210803131024.40280-6-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Introduce monotonically increasing tokens

Tokens are sequence numbers embedded in the each SCMI message header: they
are used to correlate commands with responses (and delayed responses), but
their usage and policy of selection is entirely up to the caller (usually
the OSPM agent), while they are completely opaque to the callee (i.e. SCMI
platform) which merely copies them back from the command into the response
message header.
This also means that the platform does not, can not and should not enforce
any kind of policy on received messages depending on the contained sequence
number: platform can perfectly handle concurrent requests carrying the same
identifiying token if that should happen.

Moreover the platform is not required to produce in-order responses to
agent requests, the only constraint in these regards is that in case of
an asynchronous message the delayed response must be sent after the
immediate response for the synchronous part of the command transaction.

Currenly the SCMI stack of the OSPM agent selects a token for the egressing
commands picking the lowest possible number which is not already in use by
an existing in-flight transaction, which means, in other words, that we
immediately reuse any token after its transaction has completed or it has
timed out: this policy indeed does simplify management and lookup of tokens
and associated xfers.

Under the above assumptions and constraints, since there is really no state
shared between the agent and the platform to let the platform know when a
token and its associated message has timed out, the current policy of early
reuse of tokens can easily lead to the situation in which a spurious or
late received response (or delayed_response), related to an old stale and
timed out transaction, can be wrongly associated to a newer valid in-flight
xfer that just happens to have reused the same token.

This misbehaviour on such late/spurious responses is more easily exposed on
those transports that naturally have an higher level of parallelism in
processing multiple concurrent in-flight messages.

This commit introduces a new policy of selection of tokens for the OSPM
agent: each new command transfer now gets the next available, monotonically
increasing token, until tokens are exhausted and the counter rolls over.

Such new policy mitigates the above issues with late/spurious responses
since the tokens are now reused as late as possible (when they roll back
ideally) and so it is much easier to identify such late/spurious responses
to stale timed out transactions: this also helps in simplifying the
specific transports implementation since stale transport messages can be
easily identified and discarded early on in the rx path without the need
to cross check their actual state with the core transport layer.
This mitigation is even more effective when, as is usually the case, the
maximum number of pending messages is capped by the platform to a much
lower number than the whole possible range of tokens values (2^10).

This internal policy change in the core SCMI transport layer is fully
transparent to the specific transports so it has not and should not have
any impact on the transports implementation.

Link: https://lore.kernel.org/r/20210803131024.40280-5-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add optional transport_init/exit support

Some SCMI transport could need to perform some transport specific setup
before they can be used by the SCMI core transport layer: typically this
early setup consists in registering with some other kernel subsystem.

Add the optional capability for a transport to provide a couple of init
and exit functions that are assured to be called early during the SCMI
core initialization phase, well before the SCMI core probing step.

[ Peter: Adapted RFC patch by Cristian for submission to upstream. ]

Link: https://lore.kernel.org/r/20210803131024.40280-4-cristian.marussi@arm.com
Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
[ Cristian: Fixed scmi_transports_exit point of invocation ]
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Remove scmi_dump_header_dbg() helper

Being a while that we have SCMI trace events in the SCMI stack, remove
this debug helper and its call sites.

Link: https://lore.kernel.org/r/20210803131024.40280-3-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add support for type handling in common functions

Add SCMI type handling to pack/unpack_scmi_header common helper functions.
Initialize hdr.type properly when initializing a command xfer.

Link: https://lore.kernel.org/r/20210803131024.40280-2-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix range check for the maximum number of pending messages

SCMI message headers carry a sequence number and such field is sized to
allow for MSG_TOKEN_MAX distinct numbers; moreover zero is not really an
acceptable maximum number of pending in-flight messages.

Fix accordingly the checks performed on the value exported by transports
in scmi_desc.max_msg

Link: https://lore.kernel.org/r/20210712141833.6628-3-cristian.marussi@arm.com
Reported-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
[sudeep.holla: updated the patch title and error message]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix kernel doc warnings about return values

Kernel doc validation script still complains about the following:

|No description found for return value of 'scmi_get_protocol_device'
|No description found for return value of 'scmi_devm_notifier_register'
|No description found for return value of 'scmi_devm_notifier_unregister'

Fix adding missing Return kernel-doc statements.

Link: https://lore.kernel.org/r/20210712143504.33541-1-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix possible scmi_linux_errmap buffer overflow

The scmi_linux_errmap buffer access index is supposed to depend on the
array size to prevent element out of bounds access. It uses SCMI_ERR_MAX
to check bounds but that can mismatch with the array size. It also
changes the success into -EIO though scmi_linux_errmap is never used in
case of success, it is expected to work for success case too.

It is slightly confusing code as the negative of the error code
is used as index to the buffer. Fix it by negating it at the start and
make it more readable.

Link: https://lore.kernel.org/r/20210707135028.1869642-1-sudeep.holla@arm.com
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Avoid multiple initialisations of hdr->protocol_id

Since the hdr->protocol_id is set from the scmi_protocol_instance handle
just before the transfer, there is no need to initialise the same in
scmi_xfer_get_init. Remove the unnecessary initialisations.

Link: https://lore.kernel.org/r/20210608140140.2042257-1-sudeep.holla@arm.com
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Move reinit_completion from scmi_xfer_get to do_xfer

Re-using timed out xfers in a loop can lead to issue if completion was
not properly reinitialized. Move reinit_completion from scmi_xfer_get to
do_xfer to avoid the issue.

Link: https://lore.kernel.org/r/20210606221232.33768-3-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
[sudeep.holla: moved reinit_completion instead of adding another one]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add delayed response status check

A successfully received delayed response could anyway report a failure at
the protocol layer in the message status field.

Add a check also for this error condition.

Link: https://lore.kernel.org/r/20210608103056.3388-1-cristian.marussi@arm.com
Fixes: 58ecdf03dbb9 ("firmware: arm_scmi: Add support for asynchronous commands and delayed response")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix the build when CONFIG_MAILBOX is not selected

0day CI kernel test robot reported following build error with randconfig

aarch64-linux-ld: drivers/firmware/arm_scmi/driver.o:(.rodata+0x1e0):
undefined reference to `scmi_mailbox_desc'

Fix the error by adding CONFIG_MAILBOX dependency for scmi_mailbox_desc.

Link: https://lore.kernel.org/r/20210603072631.1660963-1-sudeep.holla@arm.com
Cc: Etienne Carriere <etienne.carriere@linaro.org>
Cc: Cristian Marussi <cristian.marussi@arm.com>
Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Reset Rx buffer to max size during async commands

During an async commands execution the Rx buffer length is at first set
to max_msg_sz when the synchronous part of the command is first sent.
However once the synchronous part completes the transport layer waits
for the delayed response which will be processed using the same xfer
descriptor initially allocated. Since synchronous response received at
the end of the xfer will shrink the Rx buffer length to the effective
payload response length, it needs to be reset again.

Raise the Rx buffer length again to max_msg_sz before fetching the
delayed response to ensure full response is read correctly from the
shared memory.

Link: https://lore.kernel.org/r/20210601102421.26581-2-cristian.marussi@arm.com
Fixes: 58ecdf03dbb9 ("firmware: arm_scmi: Add support for asynchronous commands and delayed response")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
[sudeep.holla: moved reset to scmi_handle_response as it could race with
do_xfer_with_response]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add dynamic scmi devices creation

Having added the support for SCMI protocols as modules in order to let
vendors extend the SCMI core with their own additions it seems odd to
then force SCMI drivers built on top to use a static device table to
declare their devices since this way any new SCMI drivers addition
would need the core SCMI device table to be updated too.

Remove the static core device table and let SCMI drivers to simply declare
which device/protocol pair they need at initialization time: the core will
then take care to generate such devices dynamically during platform
initialization or at module loading time, as long as the requested
underlying protocol is defined in the devicetree.

Link: https://lore.kernel.org/r/20210316124903.35011-39-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add protocol modularization support

Extend SCMI protocols accounting mechanism to address possible module
usage and add the support to possibly define new protocols as loadable
modules.

Keep the standard protocols built into the SCMI core.

Link: https://lore.kernel.org/r/20210316124903.35011-38-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Make notify_priv really private

Notification private data is currently accessible via handle->notify_priv,
this data was indeed meant to be private to the notification core support
and not to be accessible by SCMI drivers. Make it private hiding it
inside instance descriptor struct scmi_info and accessible only via
dedicated helpers.

Link: https://lore.kernel.org/r/20210316124903.35011-36-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Cleanup unused core transfer helper wrappers

Remove unused core scmi_xfer wrappers now that we have migrated all
protocols to the new interface based on protocol handles.

Link: https://lore.kernel.org/r/20210316124903.35011-34-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Make references to handle const

Now that all the protocol private variable data have been moved out of
struct scmi_handle, mark all of its references as const.

Link: https://lore.kernel.org/r/20210316124903.35011-32-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Port base protocol to new interface

Port the SCMI base protocol to new protocol handles based interface.

Link: https://lore.kernel.org/r/20210316124903.35011-11-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add helper to access protocol revision/version

Add an helper to access from a protocol handle, the SCMI version data
which is exposed on sysfs. Such helper will be needed by SCMI base
protocol initialization once it will be moved to new protocol handles
scheme.

Link: https://lore.kernel.org/r/20210316124903.35011-10-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add new protocol handle core transfer ops

Add new core SCMI transfer operations based on protocol handles to
enable protocols to builds and send their own protocol specific messages.

Keep old original scmi_xfer_ operations interface as wrappers around the
new interface in order to let coexist old and new interfaces to ease
protocol by protocol migration.

In order to support such migration the above wrappers and some
additional transient code is also introduced in this commit. It will be
later removed as a whole once the full migration of protocols and SCMI
drivers will have been completed.

Link: https://lore.kernel.org/r/20210316124903.35011-9-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Convert events registration to protocol handles

Convert all refactored events registration routines to use protocol
handles.

In order to maintain bisectability and to allow protocols and drivers
to be later ported to the new protocol handle interface one by one,
introduce here also some transient code that will be removed later
in order to ease such transition.

Link: https://lore.kernel.org/r/20210316124903.35011-8-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Refactor events registration

Add a new refactored protocol events registration helper and invoke it
from the centralized initialization process triggered by get_ops() and
friends.

Also add a `get_num_sources` as a new optional callback amongst protocol
events operations. Finally remove events registration call-sites from
within the legacy protocol init routines.

Link: https://lore.kernel.org/r/20210316124903.35011-7-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Introduce devres get/put protocols operations

Expose to the SCMI drivers a new devres managed common protocols API
based on generic get/put methods and protocol handles.

All drivers still keep using the old API, no functional change.

Link: https://lore.kernel.org/r/20210316124903.35011-4-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Introduce protocol handle definitions

Add basic protocol handles definitions and private data helpers.

A protocol handle identifies a protocol instance initialized against a
specific handle, it embeds all the references to the core SCMI transfer
methods that will be needed by a protocol implementation to build and
send its own protocol specific messages using common core methods.

As such, in the interface, a protocol handle will be passed down from
the core to the protocol specific initialization callback at init time.

Anyways, at this point only definitions are introduced, all protocols
initialization code and SCMI drivers probing is still based on the old
interface, so no functional change.

Link: https://lore.kernel.org/r/20210316124903.35011-3-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Extend protocol registration interfaces

Extend common protocol registration routines and provide some new generic
protocols get/put helpers that can track protocols usage and automatically
perform the proper initialization and de-initialization on demand when
required.

Convert all standard protocols to use this new registration scheme while
keeping them all still using the usual initialization logic bound to SCMI
devices probing.

Link: https://lore.kernel.org/r/20210316124903.35011-2-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

iio/scmi: Adding support for IIO SCMI Based Sensors

This change provides ARM SCMI Protocol based IIO device.
This driver provides support for Accelerometer and Gyroscope using
SCMI Sensor Protocol extensions added in the SCMIv3.0 ARM specification

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jyoti Bhayana <jbhayana@google.com>
Link: https://lore.kernel.org/r/20210212172235.507028-2-jbhayana@google.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20210309231259.78050-2-jbhayana@google.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

firmware: arm_scmi: Fix call site of scmi_notification_exit

Call scmi_notification_exit() only when SCMI platform driver instance has
been really successfully removed.

Link: https://lore.kernel.org/r/20210112191326.29091-1-cristian.marussi@arm.com
Fixes: 6b8a69131dc63 ("firmware: arm_scmi: Enable notification core")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
[sudeep.holla: Move the call outside the list mutex locking]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add support to enumerated SCMI voltage domain device

Add SCMI voltage domain device name to the core list of supported protocol
devices so that it can be enumerated if the firmware supports it.

Link: https://lore.kernel.org/r/20201119191051.46363-3-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add voltage domain management protocol support

SCMI v3.0 introduces voltage domain protocol which provides commands to:
- Discover the voltage levels supported by a domain
- Get the configuration and voltage level of a domain
- Set the configuration and voltage level of a domain

Let us add support for the same.

Link: https://lore.kernel.org/r/20201119191051.46363-2-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add missing Rx size re-initialisation

Few commands provide the list of description partially and require
to be called consecutively until all the descriptors are fetched
completely. In such cases, we don't release the buffers and reuse
them for consecutive transmits.

However, currently we don't reset the Rx size which will be set as
per the response for the last transmit. This may result in incorrect
response size being interpretted as the firmware may repond with size
greater than the one set but we read only upto the size set by previous
response.

Let us reset the receive buffer size to max possible in such cases as
we don't know the exact size of the response.

Link: https://lore.kernel.org/r/20201012141746.32575-1-sudeep.holla@arm.com
Fixes: b6f20ff8bd94 ("firmware: arm_scmi: add common infrastructure and support for base protocol")
Reported-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Move scmi protocols registration into the driver

In preparation to enable building SCMI as a single module, let us move
the SCMI protocol registration call into the driver. This enables us
to also add unregistration of the SCMI protocols.

The main reason for this is to keep it simple instead of maintaining
it as separate modules and dealing with all possible initcall races
and deferred probe handling. We can move it as separate modules if
needed in future.

Link: https://lore.kernel.org/r/20200907195046.56615-4-sudeep.holla@arm.com
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Move scmi bus init and exit calls into the driver

In preparation to enable building scmi as a single module, let us move
the scmi bus {de-,}initialisation call into the driver.

The main reason for this is to keep it simple instead of maintaining
it as separate modules and dealing with all possible initcall races
and deferred probe handling. We can move it as separate modules if
needed in future.

Link: https://lore.kernel.org/r/20200907195046.56615-3-sudeep.holla@arm.com
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add SCMI device for system power protocol

Add SCMI device for system power protocol by just adding the name "syspower"
to the list of supported core protocol devices.

Link: https://lore.kernel.org/r/20200907174657.32466-3-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Remove fixed size fields from reports/scmi_event_header

Event reports are used to convey information describing events to the
registered user-callbacks: they are necessarily derived from the underlying
raw SCMI events' messages but they are not meant to expose or directly
mirror any of those messages data layout, which belong to the protocol
layer.

Using fixed size types for report fields, mirroring messages structure,
is at odd with this: get rid of them using more generic, equivalent,
typing.

Substitute scmi_event_header fixed size fields with generic types too and
shuffle around fields definitions to minimize implicit padding while
adapting involved functions.

Link: https://lore.kernel.org/r/20200710133919.39792-3-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Enable notification core

Initialize and enable SCMI notifications core support during bus/driver
probe phase, so that protocols can start registering their supported
events during their initialization.

Link: https://lore.kernel.org/r/20200701155348.52864-5-cristian.marussi@arm.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Use HAVE_ARM_SMCCC_DISCOVERY instead of ARM_PSCI_FW

Commit e5bfb21d98b6 ("firmware: smccc: Add HAVE_ARM_SMCCC_DISCOVERY to
identify SMCCC v1.1 and above") introduced new config option to identify
the availability of SMCCC discoverability of version and features
transparently hiding the indirect dependency on ARM_PSCI_FW.

Commit 5a897e3ab429 ("firmware: arm_scmi: fix psci dependency") just
worked around the build dependency making SCMI SMC/HVC transport depend
on ARM_PSCI_FW at the time. Since it really just relies on SMCCC directly
and not on ARM_PSCI_FW, let us move to use CONFIG_HAVE_ARM_SMCCC_DISCOVERY
instead of CONFIG_ARM_PSCI_FW.

Link: https://lore.kernel.org/r/20200625101937.51939-1-sudeep.holla@arm.com
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Use signed integer to report transfer status

Currently the trace event 'scmi_xfer_end' reports the status of the
transfer using the unsigned status field read from the firmware which
may not be easy to interpret. It may also miss to emit any timeouts
that happen in the driver resulting in emitting garbage in the status
field in those scenarios.

Let us use signed integer so that error values are emitted out after
they are mapped from firmware error formats to standard linux error
codes. While at this, also include any timeouts in the driver itself.

Link: https://lore.kernel.org/r/20200609134503.55860-1-sudeep.holla@arm.com
Cc: Jim Quinlan <james.quinlan@broadcom.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: fix psci dependency

When CONFIG_ARM_PSCI_FW is disabled but CONFIG_HAVE_ARM_SMCCC is enabled,
arm-scmi runs into a link failure:

arm-linux-gnueabi-ld: drivers/firmware/arm_scmi/smc.o: in function `smc_send_message':
smc.c:(.text+0x200): undefined reference to `arm_smccc_1_1_get_conduit'

Change from HAVE_ARM_SMCCC to ARM_PSCI_FW config dependency for now.
We rely on PSCI bindings anyways for the conduit and this should be
fine.

Link: https://lore.kernel.org/r/20200507144905.11397-1-sudeep.holla@arm.com
Fixes: 1dc6558062da ("firmware: arm_scmi: Add smc/hvc transport")
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix handling of unexpected delayed responses

Upon reception of an unexpected bogus delayed response, clear the channel
and bail-out safely.

Link: https://lore.kernel.org/r/20200420152315.21008-5-cristian.marussi@arm.com
Fixes: 4d09852b6f01 ("firmware: arm_scmi: Add support for notifications message processing")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Clear channel for delayed responses

Clear channel properly when done processing a delayed response.
This will let the platform firmware know that the channel is now free to
use it for any new delayed response or notification.

Link: https://lore.kernel.org/r/20200420152315.21008-4-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
(sudeep.holla: Updated commit log to reflect that channel is now free for
platform to use)
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Clear channel on reception of unexpected responses

When an unexpected response message is received we currently warn the user
and bail-out, ensure to also free the channel by invoking the transport
independent operation .clear_channel()

Link: https://lore.kernel.org/r/20200420152315.21008-3-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Rename .clear_notification() transport_ops

SCMI transport operation .clear_notification() is indeed a generic method
to clear the channel in a transport dependent way, as such it could be a
useful helper also in other contexts.

Rename such method as .clear_channel(), renaming accordingly also its
already existent call-sites.

No functional change.

Link: https://lore.kernel.org/r/20200420152315.21008-2-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add support for notifications message processing

Add the mechanisms to distinguish notifications from delayed responses
and command responses. Also add support to properly fetch notification
messages upon reception. Notifications processing does not continue any
further after the fetch phase.

Link: https://lore.kernel.org/r/20200327143438.5382-5-cristian.marussi@arm.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[Reworked/renamed scmi_handle_xfer_delayed_resp()]
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add receive buffer support for notifications

With all the plumbing in place, let's just add the separate dedicated
receive buffers to handle notifications that can arrive asynchronously
from the platform firmware to OS.

Also add one check to see if the platform supports any receive channels
before allocating the receive buffers: since those buffers are optionally
supported though, the whole xfer initialization is also postponed to be
able to check for their existence in advance.

Link: https://lore.kernel.org/r/20200327143438.5382-2-cristian.marussi@arm.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[Changed parameters in __scmi_xfer_info_init()]
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add smc/hvc transport

Use the value of "arm,smc-id" property from the device tree as the first
argument for SMCCC call leaving all the other arguments as zero for now.

There is no Rx, only Tx because of smc/hvc not support Rx.

Link: https://lore.kernel.org/r/1583673879-20714-3-git-send-email-peng.fan@nxp.com
Signed-off-by: Peng Fan <peng.fan@nxp.com>
[sudeep.holla: reworded commit log/subject and fixed !HAVE_ARM_SMCCC build]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Make scmi core independent of the transport type

The SCMI specification is fairly independent of the transport protocol,
which can be a simple mailbox (already implemented) or anything else.
The current Linux implementation however is very much dependent on the
mailbox transport layer.

This patch makes the SCMI core code (driver.c) independent of the
mailbox transport layer and moves all mailbox related code to a new
file: mailbox.c and all struct shared_mem related code to a new file:
shmem.c.

We can now implement more transport protocols to transport SCMI
messages.

The transport protocols just need to provide struct scmi_transport_ops,
with its version of the callbacks to enable exchange of SCMI messages.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/8698a3cec199b8feab35c2339f02dc232bfd773b.1580448239.git.viresh.kumar@linaro.org
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Move macros and helpers to common.h

Move message header specific macros and helper routines to common.h as
they will be used outside of driver.c in a later commit.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/6615db480370719b0a0241447a5f3feb8eea421f.1580448239.git.viresh.kumar@linaro.org
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Update doc style comments

Fix minor formatting issues with the doc style comments.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/1bff7c0d1ad2c8b6eeff9660421f414f8c612eb2.1580448239.git.viresh.kumar@linaro.org
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers: firmware: scmi: Extend SCMI transport layer by trace events

The SCMI transport layer communicates via mailboxes and shared memory with
firmware running on a microcontroller. It is platform specific how long it
takes to pass a SCMI message. The most sensitive requests are coming from
CPUFreq subsystem, which might be used by the scheduler.
Thus, there is a need to measure these delays and capture anomalies.
This change introduces trace events wrapped around transfer code.

According to Jim's suggestion a unique transfer_id is to distinguish
similar entries which might have the same message id, protocol id and
sequence. This is a case then there are some timeouts in transfers.

Suggested-by: Jim Quinlan <james.quinlan@broadcom.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add versions and identifier attributes using dev_groups

Platform drivers now have the option to have the platform core create
and remove any needed sysfs attribute files. Using the same, let's add
the scmi firmware and protocol version attributes as well as vendor and
sub-vendor identifiers to sysfs.

It helps to identify the firmware details from the sysfs entries similar
to ARM SCPI implementation.

Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add names to scmi devices created

Now that scmi bus provides option to create named scmi device, let us
create the default devices with names. This will help to add names for
matching to respective drivers and eventually to add multiple devices
and drivers per protocol.

Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Skip scmi mbox channel setup for addtional devices

Now that the scmi bus supports adding multiple devices per protocol,
and since scmi_create_protocol_device calls scmi_mbox_chan_setup,
we must avoid allocating and initialising the mbox channel if it is
already initialised.

Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add support for multiple device per protocol

Currently only one scmi device is created for each protocol enumerated.
However, there is requirement to make use of some procotols by multiple
kernel subsystems/frameworks. One such example is SCMI PERFORMANCE
protocol which can be used by both cpufreq and devfreq drivers.
Similarly, SENSOR protocol may be used by hwmon and iio subsystems,
and POWER protocol may be used by genpd and regulator drivers.

In order to achieve that, let us extend the scmi bus to match based
not only protocol id but also the scmi device name if one is available.

Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add support for asynchronous commands and delayed response

Messages that are sent to platform, also known as commands and can be:

1. Synchronous commands that block the channel until the requested work
has been completed. The platform responds to these commands over the
same channel and hence can't be used to send another command until the
previous command has completed.

2. Asynchronous commands on the other hand, the platform schedules the
requested work to complete later in time and returns almost immediately
freeing the channel for new commands. The response indicates the success
or failure in the ability to schedule the requested work. When the work
has completed, the platform sends an additional delayed response message.

Using the same transmit buffer used for sending the asynchronous command
even for the delayed response corresponding to it simplifies handling of
the delayed response. It's the caller of asynchronous command that is
responsible for allocating the completion flag that scmi driver can
complete to indicate the arrival of delayed response.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add mechanism to unpack message headers

In order to identify the message type when a response arrives, we need
a mechanism to unpack the message header similar to packing. Let's
add one.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Separate out tx buffer handling and prepare to add rx

Currently we pre-allocate transmit buffers only and use the first free
slot in that pre-allocated buffer for transmitting any new message that
are generally originated from OS to the platform firmware.

Notifications or the delayed responses on the other hand are originated
from the platform firmware and consumes by the OS. It's better to have
separate and dedicated pre-allocated buffers to handle the notifications.
We can still use the transmit buffers for the delayed responses.

In addition, let's prepare existing scmi_xfer_{get,put} for acquiring
and releasing a slot to identify the right(tx/rx) buffers.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add receive channel support for notifications

With scmi_mbox_chan_setup enabled to identify and setup both Tx and Rx,
let's consolidate setting up of both the channels under the function
scmi_mbox_txrx_setup.

Since some platforms may opt not to support notifications or delayed
response, they may not need support for Rx. Hence Rx is optional and
failure of setting one up is not considered fatal.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Segregate tx channel handling and prepare to add rx

The transmit(Tx) channels are specified as the first entry and the
receive(Rx) channels are the second entry as per the device tree
bindings. Since we currently just support Tx, index 0 is hardcoded at
all required callsites.

In order to prepare for adding Rx support, let's remove those hardcoded
index and add boolean parameter to identify Tx/Rx channels when setting
them up.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Reorder some functions to avoid forward declarations

Re-shuffling few functions to keep definitions and their usages close.
This is also needed to avoid too many unnecessary forward declarations
while adding new features(delayed response and notifications).

Keeping this separate to avoid mixing up of these trivial change that
doesn't affect functionality into the ones that does.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Check if platform has released shmem before using

Sometimes platfom may take too long to respond to the command and OS
might timeout before platform transfer the ownership of the shared
memory region to the OS with the response.

Since the mailbox channel associated with the channel is freed and new
commands are dispatch on the same channel, OS needs to wait until it
gets back the ownership. If not, either OS may end up overwriting the
platform response for the last command(which is fine as OS timed out
that command) or platform might overwrite the payload for the next
command with the response for the old.

The latter is problematic as platform may end up interpretting the
response as the payload. In order to avoid such race, let's wait until
the OS gets back the ownership before we prepare the shared memory with
the payload for the next command.

Reported-by: Jim Quinlan <james.quinlan@broadcom.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Use the term 'message' instead of 'command'

In preparation to adding support for other two types of messages that
SCMI specification mentions, let's replace the term 'command' with the
correct term 'message'.

As per the specification the messages are of 3 types:
commands(synchronous or asynchronous), delayed responses and notifications.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix few trivial typos in comments

While adding new comments found couple of typos that are better fixed.

s/informfation/information/
s/statues/status/

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Remove extra check for invalid length message responses

scmi_xfer_get_init ensures both transmit and receive buffer lengths are
within the maximum limits. If receive buffer length is not supplied by
the caller, it's set to the maximum limit value. Receive buffer length
is never modified after that. So there's no need for the extra check
when receive transmit completion for a command essage.

Further, if the response header length is greater than the prescribed
receive buffer length, the response buffer is truncated to the latter.

Reported-by: Jim Quinlan <james.quinlan@broadcom.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: replace of_match_device->data with of_device_get_match_data()

of_match_device can return NULL if no matching device is found though
it's highly unlikely to happen in scmi_probe as it's called only if
a valid match is found.

However we can use of_device_get_match_data() instead of
of_match_device()->data to handle NULL pointer checks and return -EINVAL
in such a scenario.

Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: fix of_node leak in scmi_mailbox_check

of_parse_phandle_with_args() requires the caller to call of_node_put() on
the returned args->np pointer. Otherwise the reference count will remain
incremented.

However, in this case, since we don't actually use the returned pointer,
we can simply pass in NULL.

Fixes: aa4f886f3893f ("firmware: arm_scmi: add basic driver infrastructure for SCMI")
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: simplify exit path by returning on error

Yet another nasty indentation left out during code restructuring. It's
must simpler to return on error instead of having unnecessary indentation.

Suggested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: remove unnecessary bitmap_zero

kcalloc zeros the memory and it's totally unnecessary to zero the bitmap
again using bitmap_zero. This patch just drops the unnecessary use of
the bitmap_zero in the context.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: rename scmi_xfer_{init,get,put}

Just after the initial patches were queued, Jonathan Cameron mentioned
that scmi_one_xfer_{get_put} were not very clear and suggested to use
scmi_xfer_{alloc,free}. While I agree to some extent, the reason not to
have alloc/free as these are preallocated buffers and these functions
just returns a reference to free slot in that preallocated array.
However it was agreed to drop "_one" as it's implicit that we are always
dealing with one slot anyways.

This patch updates the name accordingly dropping "_one" in both {get,put}
functions. Also scmi_one_xfer_init is renamed as scmi_xfer_get_init to
reflect the fact that it gets the free slots and then initialise it.

Reported-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: fix kernel-docs documentation

There are few missing descriptions for function parameters and structure
members along with certain instances where excessive function parameters
or structure members are described.

This patch fixes all of those warnings.

Reported-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: improve code readability using bitfield accessor macros

By using FIELD_{FIT,GET,PREP} and GENMASK macro accessors we can avoid
some clumpsy custom shifting and masking macros and also improve the
code better readability.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Use after free in scmi_create_protocol_device()

We need to return here instead of setting up the freed sdev device as a
transport.

Fixes: 907b6d14911d ("firmware: arm_scmi: add per-protocol channels support using idr objects")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: add per-protocol channels support using idr objects

In order to maintain the channel information per protocol, we need
some sort of list or hashtable to hold all this information. IDR
provides sparse array mapping of small integer ID numbers onto arbitrary
pointers. In this case the arbitrary pointers can be pointers to the
channel information.

This patch adds support for per-protocol channels using those idr
objects.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: refactor in preparation to support per-protocol channels

In order to support per-protocol channels if available, we need to
factor out all the mailbox channel information(Tx/Rx payload and
channel handle) out of the main SCMI instance information structure.

This patch refactors the existing channel information into a separate
chan_info structure.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: add support for polling based SCMI transfers

It would be useful to have options to perform some SCMI transfers
atomically by polling for the completion flag instead of interrupt
driven. The SCMI specification has option to disable the interrupt and
poll for the completion flag in the shared memory.

This patch adds support for polling based SCMI transfers using that
option. This might be used for uninterrupted/atomic DVFS operations
from the scheduler context.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: probe and initialise all the supported protocols

Now that we have basic support for all the protocols in the
specification, let's probe them individually and initialise them.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: add common infrastructure and support for base protocol

The base protocol describes the properties of the implementation and
provide generic error management. The base protocol provides commands
to describe protocol version, discover implementation specific
attributes and vendor/sub-vendor identification, list of protocols
implemented and the various agents are in the system including OSPM
and the platform. It also supports registering for notifications of
platform errors.

This protocol is mandatory. This patch adds support for the same along
with some basic infrastructure to add support for other protocols.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: add basic driver infrastructure for SCMI

The SCMI is intended to allow OSPM to manage various functions that are
provided by the hardware platform it is running on, including power and
performance functions. SCMI provides two levels of abstraction, protocols
and transports. Protocols define individual groups of system control and
management messages. A protocol specification describes the messages
that it supports. Transports describe the method by which protocol
messages are communicated between agents and the platform.

This patch adds basic infrastructure to manage the message allocation,
initialisation, packing/unpacking and shared memory management.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>