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: Fix incorrect error propagation in scmi_voltage_descriptors_get

scmi_voltage_descriptors_get() will incorrecly return an error code if
the last iteration of the for loop that retrieves the descriptors is
skipped due to an error. Skipping an iteration in the loop is not an
error, but the `ret` value from the last iteration will be propagated
when the function returns.

Fix by not saving return values that should not be propagated. This
solution also minimizes the risk of future patches accidentally
re-introducing this bug.

Link: https://lore.kernel.org/r/20220610140055.31491-1-ludvig.parsson@axis.com
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Ludvig Pärsson <ludvig.parsson@axis.com>
[sudeep.holla: Removed unneeded reset_rx_to_maxsz and check for return
value from scmi_voltage_levels_get as suggested by Cristian]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Avoid using extended string-buffers sizes if not necessary

Commit b260fccaebdc2 ("firmware: arm_scmi: Add SCMI v3.1 protocol extended
names support") moved all the name string buffers to use the extended buffer
size of 64 instead of the required 16 bytes. While that should be fine if
the firmware terminates the string before 16 bytes, there is possibility
of copying random data if the name is not NULL terminated by the firmware.

SCMI base protocol agent_name/vendor_id/sub_vendor_id are defined by the
specification as NULL-terminated ASCII strings up to 16-bytes in length.

The underlying buffers and message descriptors are currently bigger than
needed; resize them to fit only the strictly needed 16 bytes to avoid
any possible leaks when reading data from the firmware.

Change the size argument of strlcpy to use SCMI_SHORT_NAME_MAX_SIZE always
when dealing with short domain names, so as to limit the possibility that
an ill-formed non-NULL terminated short reply from the SCMI platform
firmware can leak stale content laying in the underlying transport shared
memory area.

While at that, convert all strings handling routines to use the preferred
strscpy.

Link: https://lore.kernel.org/r/20220608095530.497879-1-cristian.marussi@arm.com
Fixes: b260fccaebdc2 ("firmware: arm_scmi: Add SCMI v3.1 protocol extended names support")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Remove all the unused local variables

While using SCMI iterators helpers a few local automatic variables are
defined but then used only as input for sizeof operators.

cppcheck is fooled to complain about this with:

| drivers/firmware/arm_scmi/sensors.c:341:48: warning: Variable 'msg' is
| not assigned a value. [unassignedVariable]
| struct scmi_msg_sensor_list_update_intervals *msg;

Even though this is an innocuos warning, since the uninitialized variable
is at the end never used in the reported cases, fix these occurences all
over SCMI stack to avoid keeping unneeded objects on the stack.

Link: https://lore.kernel.org/r/20220530115237.277077-1-cristian.marussi@arm.com
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Sudeep Holla <sudeep.holla@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: Add SCMI v3.1 VOLTAGE_LEVEL_SET_COMPLETE

Add SCMI v3.1 voltage protocol support for asynchronous VOLTAGE_LEVEL_SET
command.

Note that, if a voltage domain is advertised to support the asynchronous
version of VOLTAGE_LEVEL_SET, the command will be issued asynchronously
unless explicitly requested to use the synchronous version by setting the
mode to SCMI_VOLTAGE_LEVEL_SET_SYNC when calling voltage_ops->level_set.

The SCMI regulator driver level_set invocation has been left unchanged
so that it will transparently use the asynchronous version if available.

Link: https://lore.kernel.org/r/20220330150551.2573938-21-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 common iterators in the voltage protocol

Make SCMI voltage protocol use the common iterator protocol helpers for
issuing the multi-part commands.

Link: https://lore.kernel.org/r/20220330150551.2573938-18-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 protocol extended names support

Using the common protocol helper implementation add support for all new
SCMIv3.1 extended names commands related to all protocols with the
exception of SENSOR_AXIS_GET_NAME.

Link: https://lore.kernel.org/r/20220330150551.2573938-12-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: Split protocol specific definitions in a dedicated header

Move some SCMI protocol specific definitions from common.h into a the new
dedicated protocols.h header so that SCMI protocols core code can include
only what it needs; this is going to be useful to avoid the risk of growing
indefinitely the dimension of common.h, especially when introducing some
common protocols helper functions.

Header common.h will continue to be included by SCMI core and transport
layers.

Link: https://lore.kernel.org/r/20220330150551.2573938-10-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 type error assignment in voltage protocol

Fix incorrect type assignment error reported by sparse as:

drivers/firmware/arm_scmi/voltage.c:159:42: warning: incorrect type in assignment (different base types)
drivers/firmware/arm_scmi/voltage.c:159:42: expected restricted __le32 [usertype] level_index
drivers/firmware/arm_scmi/voltage.c:159:42: got unsigned int [usertype] desc_index

Link: https://lore.kernel.org/r/20211115154043.49284-1-cristian.marussi@arm.com
Fixes: 2add5cacff353 ("firmware: arm_scmi: Add voltage domain management protocol support")
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: 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: Remove legacy scmi_voltage_ops protocol interface

Now that all the SCMI driver users have been migrated to the new interface
remove the legacy interface and all the transient code.

Link: https://lore.kernel.org/r/20210316124903.35011-31-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 voltage protocol to new protocols interface

Convert internals of protocol implementation to use protocol handles and
expose a new protocol operations interface for SCMI driver using the new
get/put common operations, while keeping the old handle->voltage_ops still
around to ease transition.

Remove handle->voltage_priv now unused.

Link: https://lore.kernel.org/r/20210316124903.35011-29-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>

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>