linux-kernel - Re: Linux support for a 7 segment LED display

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <a70425d3-95be-4360-9828-d5403404e803@alliedtelesis.co.nz>
Date: Mon, 19 Feb 2024 20:12:54 +0000
From: Chris Packham <Chris.Packham@...iedtelesis.co.nz>
To: Lee Jones <lee@...nel.org>
CC: Pavel Machek <pavel@....cz>, "linux-leds@...r.kernel.org"
	<linux-leds@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: Re: Linux support for a 7 segment LED display

Hi Lee,

On 20/02/24 04:13, Lee Jones wrote:
> On Sun, 11 Feb 2024, Chris Packham wrote:
>
>> Hi Blinkenlight enthusiasts,
>>
>> I'm looking for something that I figured must exists but maybe it's so
>> niche that no-one has bothered to upstream a driver for it.
>>
>> I have a requirement to support a 7-segment LED display[1] (one that can
>> display a single digit from 0-9). Hardware wise it's just a bunch of
>> individual GPIOs connected to each segment (plus an extra one for a
>> dot). I can't see anything obvious in drivers/leds but maybe I'm looking
>> in the wrong place. Or maybe it's the kind of thing on PC hardware that
>> is just driven by the BIOS without the operating system knowing about it.
>>
>> Is there an existing in-kernel driver for such a thing?
> Why would LEDs connected to a bunch of GPIOs in a specific fashion
> require a hardware driver?  Doesn't drivers/leds/leds-gpio.c already
> provide all the support you need?
Yes I could expose the individual segments as gpio-ledsbut it would be 
nicer if they worked in a more co-ordinated fashion so I didn't have to 
care about the individual segments and could just say "display 7" or 
"display 0".