[PATCH 1/2] thermal: Add support for thermal sensor for Kirkwood SoC

[Russell King - ARM Linux]

On Fri, Dec 07, 2012 at 04:59:04PM -0700, Jason Gunthorpe wrote:
> On Fri, Dec 07, 2012 at 04:24:59PM -0700, Jason Gunthorpe wrote:
> > On Sat, Dec 08, 2012 at 08:15:50AM +0900, Nobuhiro Iwamatsu wrote:
> > > Some kirkwood SoC has thermal sensor.
> > > This patch adds support for 88F6282 and 88F6283.
> > 
> > Thanks! I was just about to write this.. Looks good here.
> 
> Ah, looking closer:
> 
> $ cat /sys/class/thermal/thermal_zone0/temp 
> 37
> 
> That should be 37000, the value out of the driver should be in
> milli-Celsius.
> 
> I'd use this equation instead:
> 
> 	*temp = ((322 - reg) * 10000 * 1000) / 13625;

Be careful of math overflows... make sure you do this calculation using
unsigned arithmetic as temperatures above 157 degress will cause this
to look like a negative number using signed math... However, that
probably won't ever be noticed because at 157 degrees, you'll definitely
be outside the operating limits of the device.