Subject: Re: [PATCH 2/3][POWERPC][V2] Xilinx: of_serial support for Xilinx uart 16550.

From: Sergei Shtylyov <[email-masked]>
Date: Wed, 02 Apr 2008 23:19:53 +0400

Hello.

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 <[email-masked]>

> diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt
> index 87f4d84..af112d9 100644
> --- a/Documentation/powerpc/booting-without-of.txt
> +++ b/Documentation/powerpc/booting-without-of.txt
> @@ -2539,6 +2539,17 @@ 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 such that they
> +      use the ns16550 binding with properties to specify 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

    I'm proposing you to use the already existing "big-endian" property ISO 
"reg-offset" (used in the  nodes describing OpenPIC, for example).

WBR, Sergei