Re: CPM2 mii-bitbang: Allowing mdio on port pins other than port C

[Laurent Pinchart <laurentp@cse-semaphore.com>]

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Hi Mark,

On Monday 16 June 2008 08:19, Mark Ware wrote:
> Hello,
> 
> I am preparing a board port (from 2.4.18!) for a proprietary board which
> has it's mdio on a different port than mdc.  The current mii-bitbang
> driver in fs_enet assumes both pins are connected to port C.  I have
> created a fairly simple patch to make this more flexible, but I'm new to
> device trees and am unsure how best to describe the situation in the
> dts.
> 
> The current mdio node for CPM2 looks something like:
> 
> mdio@10d40 {
>   device_type = "mdio";
>   compatible = "fsl,cpm2-mdio-bitbang";
>   #address-cells = <1>;
>   #size-cells = <0>
>   reg = <0x10d40 0x14>;
>   fsl,mdio-pin = <12>;
>   fsl,mdc-pin = <15>;
> }
> 
> I have made mdio work on our board by adding a second reg range and
> using the first one for mdc and the second one for mdio: 
> 
>   reg = <0x10d40 0x14 0x10d60 0x14>;  // mdc=port D, mdio=port A
>   fsl,mdio-pin = <12>;    		  // PD12
>   fsl,mdc-pin = <15>;     		  // PC15
> 
> The code remains backwards compatible, in that if only one reg range is
> present it is used for both.
> 
> Is this a valid (and acceptable) way to extend the reg property?

It is. Sergej Stepanov submitted similar patches some times ago. You can find 
them at

http://www.spinics.net/lists/netdev/msg45778.html
http://www.spinics.net/lists/netdev/msg47159.html

> Is their a cleaner way I should look at?

Using the GPIO lib might be cleaner. Have a look at 
http://www.nabble.com/-PATCH-0-2--MDIO-on-GPIO-support-for-the-fs_enet-driver-ts17468958.html 
for a patch.

Best regards,

-- 
Laurent Pinchart
CSE Semaphore Belgium

Chaussee de Bruxelles, 732A
B-1410 Waterloo
Belgium

T +32 (2) 387 42 59
F +32 (2) 387 42 75

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