From: "Stephen Neuendorffer" <stephen.neuendorffer@xilinx•com>
To: "Grant Likely" <grant.likely@secretlab•ca>,
"John Linn" <linnj@xilinx•com>
Cc: linuxppc-dev@ozlabs•org
Subject: RE: [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart16550.
Date: Fri, 21 Mar 2008 09:14:57 -0700 [thread overview]
Message-ID: <20080321161421.AAFD2518061@mail63-sin.bigfish.com> (raw)
In-Reply-To: <fa686aa40803201719i7bf02ba2qd259f1a36a24d943@mail.gmail.com>
> -----Original Message-----
> From: =
linuxppc-dev-bounces+stephen.neuendorffer=3Dxilinx.com@ozlabs•org
[mailto:linuxppc-dev-
> bounces+stephen.neuendorffer=3Dxilinx.com@ozlabs•org] On Behalf Of =
Grant
Likely
> Sent: Thursday, March 20, 2008 5:19 PM
> To: John Linn
> Cc: linuxppc-dev@ozlabs•org
> Subject: Re: [PATCH 2/3] [POWERPC] Xilinx: of_serial support for
Xilinx uart16550.
>=20
> On Thu, Mar 20, 2008 at 8:43 AM, John Linn <john.linn@xilinx•com>
wrote:
> > The Xilinx 16550 uart core is not a standard 16550, because it uses
> > word-based addressing rather than byte-based addressing. As a
result,
> > it is not compatible with the open firmware 'ns16550' compatible
> > binding. This code introduces new bindings, which pass the correct
> > register base and regshift properties to the uart driver to enable
> > this core to be used. Doing this cleanly required some refactoring
of
> > the existing code.
>=20
> Personally, I'm not fond of this approach. There is already some
> traction to using the reg-shift property to specify spacing, and I
> think it would be appropriate to also define a reg-offset property to
> handle the +3 offset and then let the xilinx 16550 nodes use those.
Since the ePAPR ns16550 defines reg-shift, I don't think it makes sense
to have a separate binding for sparse16550, or for the xilinx16550
types. Personally, I like having reg-offset better than
adding three to the reg space, but I leave that up to someone who is
much more involved in ePAPR.
> > +static struct of_serial_info __devinitdata ns8250_info =3D { .type =
=3D
PORT_8250 };
> > +static struct of_serial_info __devinitdata ns16450_info =3D { =
.type
=3D PORT_16450 };
> > +static struct of_serial_info __devinitdata ns16550_info =3D { =
.type
=3D PORT_16550 };
> > +static struct of_serial_info __devinitdata ns16750_info =3D { =
.type
=3D PORT_16750 };
> > +static struct of_serial_info __devinitdata xilinx_16550_info =3D {
> > + .type =3D PORT_16550,
> > + .regshift =3D 2,
> > + .regoffset =3D 3,
> > +};
> > +static struct of_serial_info __devinitdata unknown_info =3D { =
.type
=3D PORT_UNKNOWN };
>=20
> In support of my argument; the fact that you need a table of data says
> to me that this data should really be encoded in the device tree. :-)
The table of data was always there to bind the UART types, I just added
some more info to it.
Steve
next prev parent reply other threads:[~2008-03-21 16:14 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <12060242324116-git-send-email-john.linn@xilinx.com>
2008-03-20 14:43 ` [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart 16550 John Linn
2008-03-21 0:19 ` Grant Likely
2008-03-21 9:21 ` Paul Mackerras
2008-03-21 11:39 ` Segher Boessenkool
2008-03-21 16:08 ` [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart16550 Stephen Neuendorffer
2008-03-21 16:48 ` Segher Boessenkool
2008-03-22 14:50 ` [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart 16550 Grant Likely
2008-03-22 16:06 ` Sergei Shtylyov
2008-03-24 14:09 ` Sergei Shtylyov
2008-03-24 14:27 ` Grant Likely
2008-03-24 16:15 ` Sergei Shtylyov
2008-03-24 16:48 ` Grant Likely
2008-03-24 17:03 ` Sergei Shtylyov
2008-03-25 22:48 ` John Linn
2008-03-21 13:00 ` Sergei Shtylyov
2008-03-21 15:37 ` Segher Boessenkool
2008-03-21 15:54 ` Sergei Shtylyov
2008-03-21 16:45 ` Segher Boessenkool
2008-03-21 16:50 ` [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart16550 Stephen Neuendorffer
2008-03-21 17:01 ` [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart 16550 Sergei Shtylyov
2008-03-22 15:06 ` Grant Likely
2008-03-22 16:40 ` Sergei Shtylyov
2008-03-21 16:14 ` Stephen Neuendorffer [this message]
[not found] ` <1206024232655-git-send-email-john.linn@xilinx.com>
2008-03-20 14:43 ` [PATCH 3/3] [POWERPC] Xilinx: boot " John Linn
2008-03-20 14:54 ` Grant Likely
2008-03-20 16:15 ` John Linn
2008-03-20 21:18 ` Grant Likely
[not found] ` <20080320175601.5D86217C8055@mail127-sin.bigfish.com>
2008-03-20 21:07 ` Grant Likely
2008-03-20 22:04 ` Grant Likely
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