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SubjectRe: PATCH : LEDs - possibly the most pointless kernel subsystem ever
Strangely (and perhaps sadly) enough a couple of years ago I wrote
an LED, um, "pattern generator" because, ah, someone insisted that
it would be "really cool" if the kit we were (going to) build had
a Knight Rider / Cylon "sweep"...

It had drivers for parport (I did initial development using LEDs
hanging off the back of a Thinkpad), a 5.25" SBC made by WinEnt
(LEDs on the PIIX4 GPO pins), an i2c I/O chip (used in the semi-custom
PC we eventually chose), and a test stub that just output bit patterns.

Since running patterns from user space is anti-social (and it's
difficult to get the timing good enough) there was a kernel space
"interpreter" that you could load scripts in to. Sweeps, scans,
blinks, ping-pong etc. Plus you could have multiple scripts with
LEDs "owned" by different scripts so you could do knock outs,
fill ins etc. And, of course, change scripts to reflect system
status on the fly :-)

Ok, it was a sunday afternoon hack so I got carried away a bit...

Like I say it was a couple of years ago so it probably needs some
work. But I'm quite happy to mail it to anyone that's curious. And
if any hardware manufacturers still think sweeping LEDs are cool
and trendy they're welcome to talk to me. Discreetly :-).


Mike Jagdis
Eris Associates Limited

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