Add a driver for the temperature and voltage sensors on PolarFire SoC. The temperature reports how hot the die is, and the voltages are the SoC's 1.05, 1.8 and 2.5 volt rails respectively. The hardware supports alarms in theory, but there is an erratum that prevents clearing them once triggered, so no support is added for them. The hardware measures voltage with 16 bits, of which 1 is a sign bit and the remainder holds the voltage as a fixed point integer value. It's improbable that the hardware will work if the voltages are negative, so the driver ignores the sign bits. There's no dt support etc here because this is the child of a simple-mfd syscon. Signed-off-by: Lars Randers <lranders@mail.dk> Co-developed-by: Conor Dooley <conor.dooley@microchip.com> Signed-off-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20260629-wriggle-headscarf-c85a4070dddb@spud Signed-off-by: Guenter Roeck <linux@roeck-us.net>