From: Frank Bennett <bennett78@lpbroadband.net>
To: "Benedict, Michael" <MBenedict@twacs.com>
Cc: linuxppc-embedded@ozlabs.org
Subject: Re: Early driver development resources
Date: Mon, 21 Jan 2008 12:25:14 -0700 [thread overview]
Message-ID: <4794F19A.30604@lpbroadband.net> (raw)
In-Reply-To: <BAF8B1E0BB28024A90895E746A3B610D1C2F01@twx-exch01.twacs.local>
[-- Attachment #1: Type: text/plain, Size: 1682 bytes --]
Benedict, Michael wrote:
> Hello,
> I wrote a driver for a 4 segment digital display device. I have
> a requirement that this device be used as early as possible to report
> kernel bootup state. The driver itself is pretty simple, just using
> in/out_be32() and udelay(). The problem is that I don't know how to use
> hardware resources in the early stages of booting, before I can call
> request_mem_region() and friends.
> Can anyone recommend a book / documentation / reference code /
> anything that demonstrates this, or at least could improve my
> understanding enough to accomplish this?
>
u-boot for embedded (or OpenBios) documentation, source code.
Look for splash screen code although you will want to make
multiple calls for various boot states. In the ISA days and now
PCI there are cards that display a two hex-digit POST progress
code which is a single x86, 8bit output instruction to port 0x80.
This may still be supported in closed source BIOS distributions.
Not sure what they do now with PCIe since it will take more than
a single, simple processor instruction.
-Frank Bennett
> Many thanks,
> Michael
>
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
>
--
*/Frank Bennett
President/*
Mathegraphics,LLC
613 Bentley Pl
Fort Collins,CO 80526
970-229-9269 (hm) 970-402-9269 (cell)
www.mathegraphics.com <http://www.mathegraphics.com>
bennett78@lpbroadband.net <mailto:bennett78@lpbroadband.net>
"I think there's a world market for about five computers."
-- attr. Thomas J. Watson (Chairman of the Board, IBM), 1943
[-- Attachment #2: Type: text/html, Size: 3106 bytes --]
prev parent reply other threads:[~2008-01-21 19:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-21 18:20 Early driver development resources Benedict, Michael
2008-01-21 19:25 ` Frank Bennett [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4794F19A.30604@lpbroadband.net \
--to=bennett78@lpbroadband.net \
--cc=MBenedict@twacs.com \
--cc=linuxppc-embedded@ozlabs.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.