Siemens Simatic Industrial PCs can monitor the voltage of the CMOS
battery with two bits that indicate low or empty state. This can be GPIO
or PortIO based.
Here we model that as a hwmon voltage. The core driver does the PortIO
and provides boilerplate for the GPIO versions. Which are split out to
model runtime dependencies while allowing fine-grained kernel
configuration.
Signed-off-by: Henning Schild <henning.schild@siemens.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230706154831.19100-3-henning.schild@siemens.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
This mainly implements detection of these devices and will allow
secondary drivers to work on such machines.
The identification is DMI-based with a vendor specific way to tell them
apart in a reliable way.
Drivers for LEDs and Watchdogs will follow to make use of that platform
detection.
There is also some code to allow secondary drivers to find GPIO memory,
that needs to be in place because the pinctrl drivers do not come up.
Signed-off-by: Henning Schild <henning.schild@siemens.com>
Link: https://lore.kernel.org/r/20211213120502.20661-2-henning.schild@siemens.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
