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

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Message-ID: <48353E45.2080903@cam.ac.uk>
Date:	Thu, 22 May 2008 10:35:01 +0100
From:	Jonathan Cameron <jic23@....ac.uk>
To:	David Brownell <david-b@...bell.net>
CC:	Jean Delvare <khali@...ux-fr.org>,
	spi-devel-general@...ts.sourceforge.net,
	Jonathan Cameron <Jonathan.Cameron@...il.com>,
	LM Sensors <lm-sensors@...sensors.org>,
	linux-kernel@...r.kernel.org, Dmitry Torokhov <dtor@...l.ru>
Subject: Re: [spi-devel-general] Accelerometer,	Gyros and ADC's etc within
 the kernel.

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
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