From: erik quanstrom <quanstro@quanstro.net>
To: 9fans@9fans.net
Subject: Re: [9fans] "gpio device" for Plan 9
Date: Tue, 31 Dec 2013 14:18:51 -0500 [thread overview]
Message-ID: <821cb256954ce0bf4ad389ffe5eafa50@mikro> (raw)
In-Reply-To: <4657D0DD-A119-4E19-B50D-EBCE5861F9F8@gmail.com>
On Tue Dec 31 12:47:30 EST 2013, krystian.lew@gmail.com wrote:
> Thank you for the feedback, i think "ctl" file and numbering scheme
> selection could do the job. And maybe it could help to establish
> reasonable base for SPI and others.
>
> Is it safe to just generate new dev tree - to return either BCM,
> WiringPi or board pin set - based on pin numbering scheme selection
> made by user? What will happen if a process would try o read/write
> from/to pin when numbering scheme is changed? I tried to look at
> devproc.c (what would happen when process dies and something is
> reading its /proc entries) but i can^[.F^[N"t see any specific
> precautions there.
(sorry about the funny formatting. the header specifies
Content-Type: text/plain; charset=iso-2022-jp-2
which might be the same as iso-2022-jp, but i haven't tracked this down yet.)
there is a 1 character argument to attach. you can avoid the issue
by letting the attach argument specify which scheme you'd like, e.g.:
mount -a '#Gx' /dev
> Regarding ISRs - this is not implemented yet. Polling at the moment
> is the only option. But maybe "events^[$B!I^[(B file, with data
> populated by interrupt routine would be the answer. Is it correct
> Plan 9 way of doing things? QIO looks very suitable for this purpose.
"long" reads are an established way to avoid polling. plan 9
was doing this long before i'd heard the term. the network drivers
work this way.
- erik
next prev parent reply other threads:[~2013-12-31 19:18 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-29 22:04 Krystian Lewandowski
2013-12-29 22:34 ` erik quanstrom
2013-12-30 7:32 ` Skip Tavakkolian
2013-12-30 22:38 ` Shane Morris
[not found] ` <35A33F66-EF03-4659-ABA1-F25082DBFE41@gmail.com>
2013-12-31 17:46 ` Krystian Lewandowski
2013-12-31 19:18 ` erik quanstrom [this message]
2013-12-31 19:37 ` Shane Morris
2013-12-31 19:48 ` Skip Tavakkolian
2013-12-31 19:50 ` erik quanstrom
2013-12-31 20:45 ` Shane Morris
2013-12-31 22:03 ` erik quanstrom
2013-12-31 22:17 ` Shane Morris
2013-12-31 22:52 ` erik quanstrom
2013-12-31 22:57 ` Krystian Lewandowski
2013-12-31 23:16 ` Shane Morris
2013-12-31 23:35 ` Shane Morris
2014-01-01 0:04 ` Krystian Lewandowski
2014-01-01 0:12 ` Shane Morris
2014-01-01 1:12 ` Matthew Veety
2014-01-01 11:38 ` Richard Miller
2014-01-01 22:16 ` erik quanstrom
2014-02-28 23:30 ` Krystian Lewandowski
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