[U-Boot] [PATCH 15/17] Add console command to access io space registers

[Vadim Bendebury]

On Sat, Nov 3, 2012 at 8:26 AM, Wolfgang Denk <wd at denx.de> wrote:

> Dear Simon Glass,
>
> In message <1351902453-27956-16-git-send-email-sjg at chromium.org> you
> wrote:
> > From: Vadim Bendebury <vbendeb at chromium.org>
> >
> > Provide u-boot console functions to access IO space registers. A no
> > thrills implementation, accessing one register at a time.
> >
> > For example:
> >     boot > iod 80
> >     0080: 00000094
> >     boot > iod.w 80
> >     0080: 0094
> >     boot > iod.b 80
> >     0080: 94
> >     boot > iow.b 0x80 12
> >     boot > iod 0x80
> >     0080: 00000012
>
> What are the exact use cases where this is necessary, i. e. where
> plain md / mw does not work?
>
>
Wolfgang,

the x86 architecture defines this different kind of address space, device
IO, in addition to memory address space. This is a remnant of the days when
address lines were sparse.

On typical x86 systems devices are accessed through this device IO space,
and this patch adds a command which allows the operator to read and write
device registers on such systems.

Cheers,
/vb

Best regards,
>
> Wolfgang Denk
>
> --
> DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
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