From: plagnioj@jcrosoft•com (Jean-Christophe PLAGNIOL-VILLARD)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC 1/5] ARM: at91: add general purpose backup register (GPBR) support
Date: Thu, 11 Apr 2013 16:53:03 +0200 [thread overview]
Message-ID: <20130411145303.GA25242@game.jcrosoft.org> (raw)
In-Reply-To: <20130411123908.GB21305@localhost>
On 14:39 Thu 11 Apr , Johan Hovold wrote:
> On Mon, Apr 08, 2013 at 12:04:17PM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > On 10:46 Mon 08 Apr , Johan Hovold wrote:
> > > On Mon, Apr 08, 2013 at 09:33:29AM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > > > On 17:12 Sun 07 Apr , Johan Hovold wrote:
> > > > >
> > > > > Add General Purpose Backup Register (GPBR) support.
> > > > >
> > > > > Most at91 SoCs have at least four 32-bit General Purpose Backup
> > > > > Registers (GPBR) powered by backup-power (VDDBU). One such register is
> > > > > currently used by rtc-at91sam9 driver to store the RTC time base.
> > > > >
> > > > > Make sure the registers are mapped by arch setup code and add generic
> > > > > accessors for in-kernel use.
> > > > >
> > > > > This is a step in adding device-tree support to the rtc-at91sam9 driver.
> > > > >
> > > > This is a regression
> > > >
> > > > we loose the tracking of what request and use the GPBR
> > >
> > > Implementing the GPBR accessors using a simple global resource was one
> > > quick way forward to decouple and generalise the GPBR. Of course, this
> > > could be turned into a more elaborate framework or driver where
> > > registers are requested and released by other drivers and possibly also
> > > by user-space.
> > yes must as we used on SAMA5 to pass the boot source from the firstage
> > of the boot loader to the other software
>
> Could you please elaborate on this; how is the GPBR used, how many
> registers, and when is it accessed?
The second stage bootloader store the content of the boot mode passs via r4
from the Rom-Code in the 2nd gpbr
>
> Is there already code in at91/at91-3.10-soc or are you referring to
> a userspace consumer?
no user you can see the code in barebox
you can see the code of barebox here
http://git.linupdate.org/git?p=barebox.git;a=shortlog;h=refs/heads/delivery/sama5-release-bootmode
Best Regards,
J.
>
> Thanks,
> Johan
next prev parent reply other threads:[~2013-04-11 14:53 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-04 3:54 [PATCH] rtc: rtc-at91sam9.c add DT support Douglas Gilbert
2013-04-04 8:11 ` Nicolas Ferre
2013-04-04 13:25 ` Douglas Gilbert
2013-04-04 14:08 ` Nicolas Ferre
2013-04-04 19:14 ` Douglas Gilbert
2013-04-07 15:09 ` Johan Hovold
[not found] ` <1365347572-14972-1-git-send-email-jhovold@gmail.com>
2013-04-08 7:33 ` [RFC 1/5] ARM: at91: add general purpose backup register (GPBR) support Jean-Christophe PLAGNIOL-VILLARD
2013-04-08 8:46 ` Johan Hovold
2013-04-08 10:04 ` Jean-Christophe PLAGNIOL-VILLARD
2013-04-11 12:39 ` Johan Hovold
2013-04-11 14:53 ` Jean-Christophe PLAGNIOL-VILLARD [this message]
[not found] ` <1365347572-14972-2-git-send-email-jhovold@gmail.com>
2013-04-08 7:35 ` [RFC 2/5] ARM: at91/dts: " Jean-Christophe PLAGNIOL-VILLARD
[not found] ` <1365347572-14972-4-git-send-email-jhovold@gmail.com>
2013-04-08 7:38 ` [RFC 4/5] RTC: rtc-at91sam9: add device-tree support Jean-Christophe PLAGNIOL-VILLARD
2013-04-08 9:00 ` Johan Hovold
2013-04-08 9:57 ` Nicolas Ferre
2013-04-08 10:03 ` Jean-Christophe PLAGNIOL-VILLARD
2013-04-08 10:42 ` Nicolas Ferre
2013-04-08 11:02 ` Jean-Christophe PLAGNIOL-VILLARD
2013-04-08 10:48 ` Johan Hovold
2013-04-08 11:08 ` Jean-Christophe PLAGNIOL-VILLARD
2013-04-08 10:38 ` Johan Hovold
2013-04-08 11:11 ` Jean-Christophe PLAGNIOL-VILLARD
2013-04-11 12:57 ` Johan Hovold
2013-04-04 8:16 ` [PATCH] rtc: rtc-at91sam9.c add DT support Johan Hovold
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