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 <[EMAIL PROTECTED]>
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 <><
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