From: Arnd Bergmann <arnd@arndb•de>
To: linuxppc-dev@ozlabs•org
Cc: John Linn <john.linn@xilinx•com>
Subject: Re: [PATCH 2/3] [POWERPC][V3] Xilinx: of_serial support for Xilinx uart 16550.
Date: Thu, 3 Apr 2008 01:34:10 +0200 [thread overview]
Message-ID: <200804030134.11437.arnd@arndb.de> (raw)
In-Reply-To: <20080402232213.5D87515B8067@mail37-sin.bigfish.com>
On Thursday 03 April 2008, John Linn wrote:
> The Xilinx 16550 uart core is not a standard 16550 because it uses
> word-based addressing rather than byte-based addressing. With
> additional properties it is compatible with the open firmware
> 'ns16550' compatible binding.
>
> This code updates the of_serial driver to handle the reg-offset
> and reg-shift properties to enable this core to be used.
>
> Signed-off-by: John Linn <john.linn@xilinx•com>
I may not be the best driver maintainer, but please keep the illusion
alive for me and Cc me on patches to drivers I wrote ;-)
> diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt
> index 87f4d84..4066ec8 100644
> --- a/Documentation/powerpc/booting-without-of.txt
> +++ b/Documentation/powerpc/booting-without-of.txt
> @@ -2539,6 +2539,16 @@ platforms are moved over to use the flattened-device-tree model.
> differ between different families. May be
> 'virtex2p', 'virtex4', or 'virtex5'.
>
> + iv) Xilinx Uart 16550
> +
> + Xilinx UART 16550 devices are very similar to the NS16550 but with
> + different register spacing and an offset from the base address.
> +
> + Requred properties:
> + - clock-frequency : Frequency of the clock input
> + - reg-offset : A value of 3 is required
> + - reg-shift : A value of 2 is required
> +
> More devices will be defined as this spec matures.
Since it is not really compatible with ns16550, shouldn't you at least specify
a different "compatible" property? That way, the driver won't do incorrect
accesses when you try to use an old driver with a device tree that specifies
one of these.
> @@ -49,6 +50,17 @@ static int __devinit of_platform_serial_setup(struct of_device *ofdev,
>
> spin_lock_init(&port->lock);
> port->mapbase = resource.start;
> +
> + /* Check for shifted address mapping */
> + prop = of_get_property(np, "reg-offset", &prop_size);
> + if (prop && (prop_size == sizeof(u32)))
> + port->mapbase += *prop;
> +
> + /* Check for registers offset within the devices address range */
> + prop = of_get_property(np, "reg-shift", &prop_size);
> + if (prop && (prop_size == sizeof(u32)))
> + port->regshift = *prop;
> +
> port->irq = irq_of_parse_and_map(np, 0);
> port->iotype = UPIO_MEM;
> port->type = type;
This part looks good to me.
Arnd <><
next prev parent reply other threads:[~2008-04-02 23:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-02 23:22 [PATCH 2/3] [POWERPC][V3] Xilinx: of_serial support for Xilinx uart 16550 John Linn
2008-04-02 23:34 ` Arnd Bergmann [this message]
2008-04-03 2:43 ` Grant Likely
2008-04-03 4:16 ` Arnd Bergmann
2008-04-03 13:29 ` John Linn
2008-04-03 22:36 ` [PATCH 2/3] [POWERPC][V3] Xilinx: of_serial support for Xilinxuart 16550 Stephen Neuendorffer
2008-04-05 14:45 ` [PATCH 2/3] [POWERPC][V3] Xilinx: of_serial support for Xilinx uart 16550 Josh Boyer
2008-04-08 2:44 ` David Gibson
2008-04-03 12:25 ` Sergei Shtylyov
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=200804030134.11437.arnd@arndb.de \
--to=arnd@arndb$(echo .)de \
--cc=john.linn@xilinx$(echo .)com \
--cc=linuxppc-dev@ozlabs$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox