Re: best way to handle LEDs

[Paul Mundt <lethal@linux-sh.org>]

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On Wed, Nov 02, 2005 at 12:44:59AM +0100, Pavel Machek wrote:
> Handheld machines have limited number of software-controlled status
> LEDs. Collie, for example has two of them; one is labeled "charge" and
> second is labeled "mail".
> 
> At least the "mail" led should be handled from userspace, and it would
> be nice if (at least) different speeds of blinking could be used --
> original Sharp ROM uses at least:
> 
> yellow off: 	not charging
> yellow on:	charging
> yellow fast blink: charge error
> 
> I think even slow blinking was used somewhere. I have some code from
> John Lenz (attached); it uses sysfs interface, exports led collor, and
> allows setting different frequencies.
> 
> Is that acceptable, or should some other interface be used?
> 
I would also be in favour of having a more generic interface for
something like this (as opposed to each architecture rolling their own).

For example, sh currently has a very simplistic framework in place where
LED manipulation is done via a heartbeat callback in the machvec for each
timer tick, so it would be nice to have things somewhat more flexible in
this regard (especially for boards with multi-coloured LEDs, and for
userspace input).

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