firmware: arm_scmi: Check beforehand if the perf domain set operations are allowed

Certain SCMI performance domains may have restrictions on the set level
and/or limits operation. If the set level/limits are performed by an
agent who is not allowed to do so may get SCMI_ERR_SUPPORT. However,
since this information about the domain is already known to the
agent(OSPM here) obtained via PERF_DOMAIN_ATTRIBUTES, the agent(OSPM)
can avoid making PERF_LEVEL_SET and PERF_LIMITS_SET calls to the firmware.

Add those checks and return -ENOTSUPP to the caller without interacting
with the firmware based on the information collected during the domain
enumeration stage.

Signed-off-by: xinglong.yang <xinglong.yang@cixtech.com>
Link: https://lore.kernel.org/r/20231109082855.472681-1-xinglong.yang@cixtech.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
index c2435be0ae1be851b58fafef7242fc54bcf43774..f5a063b0b1ab9c23d62a6910c6920479dc2d3428 100644 (file)
--- a/drivers/firmware/arm_scmi/perf.c
+++ b/drivers/firmware/arm_scmi/perf.c
@@ -504,6 +504,9 @@ static int scmi_perf_limits_set(const struct scmi_protocol_handle *ph,
        if (IS_ERR(dom))
                return PTR_ERR(dom);
 
+       if (!dom->set_limits)
+               return -EOPNOTSUPP;
+
        if (PROTOCOL_REV_MAJOR(pi->version) >= 0x3 && !max_perf && !min_perf)
                return -EINVAL;
 
@@ -654,6 +657,9 @@ static int scmi_perf_level_set(const struct scmi_protocol_handle *ph,
        if (IS_ERR(dom))
                return PTR_ERR(dom);
 
+       if (!dom->info.set_perf)
+               return -EOPNOTSUPP;
+
        if (dom->level_indexing_mode) {
                struct scmi_opp *opp;