[PATCH] of: added documentation for spi chipselects

[Wolfram Sang]

On Tue, Feb 16, 2010 at 07:39:57PM +0100, Ernst Schwab wrote:
> From: Ernst Schwab <eschwab at online.de>
> 
> Added devicetree binding documentation for gpios used as chipselect. The
> code to evaluate these is already present in spi_mpc8xxx.c.
> 
> Signed-off-by: Ernst Schwab <eschwab at online.de>
> ---
> diff -upr a/Documentation/powerpc/dts-bindings/fsl/spi.txt b/Documentation/powerpc/dts-bindings/fsl/spi.txt
> --- a/Documentation/powerpc/dts-bindings/fsl/spi.txt
> +++ b/Documentation/powerpc/dts-bindings/fsl/spi.txt
> @@ -13,6 +13,11 @@ Required properties:
>  - interrupt-parent : the phandle for the interrupt controller that
>    services interrupts for this device.
>  
> +Optional properties:
> +- gpios : specifies the gpio pins to be used for chipselects. 
> +  The gpios will be referred to as reg=<index> in the SPI child nodes.
> +  If unspecified, a single SPI device without a chip select can be used.

Minor: I'd prefer spaces around the '='.

> +
>  Example:
>  	spi at 4c0 {
>  		cell-index = <0>;
> @@ -21,4 +26,6 @@ Example:
>  		interrupts = <82 0>;
>  		interrupt-parent = <700>;
>  		mode = "cpu";
> +		gpios = <&gpio 18 1	// device reg=<0>, low-active
> +			 &gpio 19 1>;	// device reg=<1>, low-active

I'd drop the comments. GPIO controllers may have private xlate-functions, so
'1' could theoretically mean something else than "low-active" (although in
practice it hopefully won't).

>  	};
> 
> 
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-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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