Re: [spi-devel-general] Accelerometer, Gyros and ADC's etc withinthe kernel.

From: Jonathan Cameron
Date: Thu May 22 2008 - 05:35:23 EST

Hi David,
On Tuesday 20 May 2008, Jean Delvare wrote:
This all sounds quite different from our hwmon drivers. Our hwmon
drivers read all the sensor values at once and cache the readings for a
couple seconds, so you can't get an instant reading at any time, and
they also don't support interrupts in general.

That's something of an issue when the hardware monitor
triggers alarms though, right? I couldn't figure out
how to get a TMP75 alert out to any userspace code that
would care, to pick one example, even after teaching
the i2c core how to handle SMBus alerts. ;)

I suppose this just emphasizes the point made by Hans
that we kind of need (industrial) "control" components
(or "data acquisition"?) not just "monitoring" ones.
I get the feeling even the name is going to evolve for some time to come, getting broader as and when we add more classes of device.
Such alarms are of course different from the "data
ready" signals of an accelerometer.
Whilst this is true, most accelerometers also have "alarm" triggers, for example
the ST LIS3L02DQ will raise a pin on configurable conditions such as thresholds
and even a double click detector (though I've never tried them!). I suppose we
will ideally support this functionality as well.
Jonathan Cameron
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at