linux/Documentation/hwmon/ftsteutates.rst
Armin Wolf 9aba03fb51 hwmon: (ftsteutates) Fix scaling of measurements
[ Upstream commit ca8fd8c16a ]

A user complained that the ftsteutates driver was displaying
bogus values since its introduction. This happens because the
sensor measurements need to be scaled in order to produce
meaningful results:
- the fan speed needs to be multiplied by 60 since its in RPS
- the temperature is in degrees celsius and needs an offset of 64
- the voltage is in 1/256 of 3.3V

The offical datasheet says the voltage needs to be divided by 256,
but this is likely an off-by-one-error, since even the BIOS
devides by 255 (otherwise 3.3V could not be measured).

The voltage channels additionally need a board-specific multiplier,
however this can be done by the driver since its board-specific.

The reason the missing scaling of measurements is the way Fujitsu
used this driver when it was still out-of-tree. Back then, all
scaling was done in userspace by libsensors, even the generic one.

Tested on a Fujitsu DS3401-B1.

Fixes: 08426eda58 ("hwmon: Add driver for FTS BMC chip "Teutates"")
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20221224041855.83981-2-W_Armin@gmx.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-03-10 09:33:10 +01:00

38 lines
1.2 KiB
ReStructuredText

Kernel driver ftsteutates
=========================
Supported chips:
* FTS Teutates
Prefix: 'ftsteutates'
Addresses scanned: I2C 0x73 (7-Bit)
Author: Thilo Cestonaro <thilo.cestonaro@ts.fujitsu.com>
Description
-----------
The BMC Teutates is the Eleventh generation of Superior System
monitoring and thermal management solution. It is builds on the basic
functionality of the BMC Theseus and contains several new features and
enhancements. It can monitor up to 4 voltages, 16 temperatures and
8 fans. It also contains an integrated watchdog which is currently
implemented in this driver.
The 4 voltages require a board-specific multiplier, since the BMC can
only measure voltages up to 3.3V and thus relies on voltage dividers.
Consult your motherboard manual for details.
To clear a temperature or fan alarm, execute the following command with the
correct path to the alarm file::
echo 0 >XXXX_alarm
Specification of the chip can be found here:
- ftp://ftp.ts.fujitsu.com/pub/Mainboard-OEM-Sales/Services/Software&Tools/Linux_SystemMonitoring&Watchdog&GPIO/BMC-Teutates_Specification_V1.21.pdf
- ftp://ftp.ts.fujitsu.com/pub/Mainboard-OEM-Sales/Services/Software&Tools/Linux_SystemMonitoring&Watchdog&GPIO/Fujitsu_mainboards-1-Sensors_HowTo-en-US.pdf