[v4,0/2] hwmon: scmi: Scale values to target desired HWMON units

Message

Florian Fainelli May 8, 2019, 5 p.m. UTC

Hi Sudeep, Guenter,

This patch series adds support for scaling SCMI sensor values read from
firmware. Sudeep, let me know if you think we should be treating scale
== 0 as a special value to preserve some firmware compatibility (not
that this would be desired).

Changes in v4:
- deal with overflow in the caller of __pow10() as suggested by Guenter
  which makes us rework a bit how the value argument/return value are
  passed
- don't harcode the latest power of 10 factor to be 18, just rely on
  overflowing the u64 value instead

Changes in v3:

- add a local __pow10 function to scmi-hwmon.c while a plan to provide
  a generic function is figured out.
- add check on power > 18 which would overflow a 64-bit unsigned integer
- use div64_u64() to properly divide a 64-bit quantity with an unsigned
  64-bit quantity

Changes in v2:

- added a helper function in kernel.h: __pow10()
- made the scale in scmi_sensor_info an s8 type, added defines for
  checking the sign bit and sign extending with a mask
- simplify computations in hwmon driver

Florian Fainelli (2):
  firmware: arm_scmi: Fetch and store sensor scale
  hwmon: scmi: Scale values to target desired HWMON units

 drivers/firmware/arm_scmi/sensors.c |  6 ++++
 drivers/hwmon/scmi-hwmon.c          | 46 +++++++++++++++++++++++++++++
 include/linux/scmi_protocol.h       |  1 +
 3 files changed, 53 insertions(+)