pldm: Enable polling sensors individually

[spargaon]

Sensors are polling as part of the polling loop in sensor manager. There is no provision to read a sensor individually. Add the provision to read a sensor
using D-Bus infrastructure.

[spargaon]

Can poll sensors individually, especially sensor ReadBIOSBoostFMax (sensor id 8) that is not part of polling loop run by sensor manager whereas sensor ReadMaxPackagePowerLimit (sensor id 4) is.

Please refer to:
Section 3.3 of https://amd.atlassian.net/wiki/spaces/ES/pages/982097049/Venice+-+PLDM+Verification

root@congo-0555:/tmp# busctl get-property xyz.openbmc_project.PLDM /xyz/openbmc_project/sensors/frequency/Processor0_ReadBIOSBoostFMax xyz.openbmc_project.Sensor.Value Value
d 0

root@congo-0555:/tmp# busctl get-property xyz.openbmc_project.PLDM /xyz/openbmc_project/sensors/frequency/Processor0_ReadBIOSBoostFMax xyz.openbmc_project.Sensor.Value Value
d 4e+09

root@congo-0555:/tmp# busctl get-property xyz.openbmc_project.PLDM /xyz/openbmc_project/sensors/power/Processor0_ReadMaxPackagePowerLimit xyz.openbmc_project.Sensor.Value Value
d 500

[mahkurap]

Making the Sensor Reading Value forced everytime - is changing the OpenBMC sensor interface which works on periodic polling, and returning the sensor Value from the cached value.

Instead, I think we should have a different interface/method called "ReadNow". This method will update the cache value.
Pros: Existing OpenBMC sensor cache implementation will not have any impact.
Cons: One additional dbus call to make to update the cache value.

Another alternative:
have the Sync reading only for the sensors that have a corresponding effecter, and do it only in AMD specific compile time flag.

May be we need to take Sreedhar/Supreeth's opinion.

[spargaon]

Users will have to distinguish between sensors that are polled and that are not polled, listed on
https://amd.atlassian.net/wiki/spaces/ES/pages/982097049/Venice+-+PLDM+Verification
3.3.1 Sensors that are polled periodically (every 5 seconds)
and
3.3.2 Sensors that are not polled

The new interface should only be used for sensors that are not polled, so uses will have to be aware of the
nature of a sensor, pollable versus non-pollable.

[spargaon]

root@congo-0555:~# busctl get-property xyz.openbmc_project.PLDM /xyz/openbmc_project/sensors/power/Processor0_ReadMaxPackagePowerLimit xyz.openbmc_project.Sensor.Value Value
d 500

root@congo-0555:~# busctl get-property xyz.openbmc_project.PLDM /xyz/openbmc_project/sensors/frequency/Processor0_ReadBIOSBoostFMax xyz.openbmc_project.Sensor.Value Value
d 0

root@congo-0555:# busctl get-property xyz.openbmc_project.PLDM /xyz/openbmc_project/sensors/frequency/Processor0_ReadBIOSBoostFMax xyz.openbmc_project.Sensor.Value Value
d 4e+09
root@congo-0555:#

getSensorReading is invoked only for sensor ReadBIOSBoostFMax (id 8) which is not polled but, the value returned is the fetched from PMFW and cached.
getSensorReading is not invoked for sensor ReadMaxPackagePowerLimit (id 4) is polled, the value returned is the cache value.

<6> Match found: Sensor 256 has corresponding Effecter. Disabling polling.
<6> Get reading for sensor Id: 8
<6> Get reading for sensor Id: 8

[spargaon]

root@congo-0555:~# pldmtool mctpRaw -m 17 -e 1 -d 0x1 0x80 0x2 0x11 0x04 0x00 0x00 0x00
pldmtool: Tx: 01 80 02 11 04 00 00 00
pldmtool: Rx: 00 02 11 00 04 00 00 01 01 01 20 a1 07 00

root@congo-0555:~# pldmtool mctpRaw -m 17 -e 1 -d 0x1 0x80 0x2 0x11 0x08 0x00 0x00 0x00
pldmtool: Tx: 01 80 02 11 08 00 00 00
pldmtool: Rx: 00 02 11 00 04 00 00 01 01 01 a0 0f 00 00