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| author | Cristian Marussi <cristian.marussi@arm.com> | 2023-12-01 14:58:58 +0100 |
|---|---|---|
| committer | Sudeep Holla <sudeep.holla@arm.com> | 2023-12-01 17:46:10 +0100 |
| commit | b5efc28a754d2e90b9d52ba5aaa051cc24a5c85d (patch) | |
| tree | 4d8be46e4eb0b1298b8d1f85db303d53481d5cbb /drivers/firmware/arm_scmi/driver.c | |
| parent | firmware: arm_scmi: Increase the maximum opp count in the perf protocol (diff) | |
| download | linux-b5efc28a754d2e90b9d52ba5aaa051cc24a5c85d.tar.xz linux-b5efc28a754d2e90b9d52ba5aaa051cc24a5c85d.zip | |
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>
Diffstat (limited to 'drivers/firmware/arm_scmi/driver.c')
| -rw-r--r-- | drivers/firmware/arm_scmi/driver.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index 3eb19ed6f148..a9f70e6e58ac 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -85,6 +85,7 @@ struct scmi_xfers_info { * @gid: A reference for per-protocol devres management. * @users: A refcount to track effective users of this protocol. * @priv: Reference for optional protocol private data. + * @version: Protocol version supported by the platform as detected at runtime. * @ph: An embedded protocol handle that will be passed down to protocol * initialization code to identify this instance. * @@ -97,6 +98,7 @@ struct scmi_protocol_instance { void *gid; refcount_t users; void *priv; + unsigned int version; struct scmi_protocol_handle ph; }; @@ -1392,15 +1394,17 @@ static int version_get(const struct scmi_protocol_handle *ph, u32 *version) * * @ph: A reference to the protocol handle. * @priv: The private data to set. + * @version: The detected protocol version for the core to register. * * Return: 0 on Success */ static int scmi_set_protocol_priv(const struct scmi_protocol_handle *ph, - void *priv) + void *priv, u32 version) { struct scmi_protocol_instance *pi = ph_to_pi(ph); pi->priv = priv; + pi->version = version; return 0; } @@ -1849,6 +1853,12 @@ scmi_alloc_init_protocol_instance(struct scmi_info *info, devres_close_group(handle->dev, pi->gid); dev_dbg(handle->dev, "Initialized protocol: 0x%X\n", pi->proto->id); + if (pi->version > proto->supported_version) + dev_warn(handle->dev, + "Detected UNSUPPORTED higher version 0x%X for protocol 0x%X." + "Backward compatibility is NOT assured.\n", + pi->version, pi->proto->id); + return pi; clean: |