2016-07-25 16:15 GMT+02:00 Thierry Reding <thierry.reding@xxxxxxxxx>:
> On Mon, Jul 25, 2016 at 03:16:28PM +0200, Mirza Krak wrote:
>> 2016-07-25 13:30 GMT+02:00 Thierry Reding <thierry.reding@xxxxxxxxx>:
> Yes, that clarifies many things. The presence of an external, address-
> based chip-select is essential information in order to describe this
> setup properly.
>
> Given that the external chip select is entirely invisible to software, I
> think a more accurate description of your setup would be:
>
> gmi@70090000 {
> ...
>
> /* for the chip select */
> #address-cells = <1>;
> #size-cells = <0>;
>
> /*
> * Technically this could be used to translate the range from
> * 0x48000000 to 0x4fffffff into a different range, but that
> * no longer works because of the #address-cells. Does this
> * matter?
> */
> ranges;
>
> bus@0 {
> compatible = "simple-bus";
> reg = <0>;
>
> #address-cells = <1>;
> #size-cells = <1>;
>
> can@48000000 {
> reg = <0x48000000 0x100>;
> ...
> };
>
> can@48040000 {
> reg = <0x48040000 0x100>;
> ...
> };
> };
> };
>
Finally got around to test this. Above example had some issues, or I
am doing something wrong.
First of, the address parser does not seem to like that #size-cells =
<0> when ranges are empty. Got following warning from device tree
compiler:
Warning (ranges_format): /nor@70009000 has empty "ranges" property but
its #size-cells (0) differs from / (1)
and on boot:
[ 0.399357] prom_parse: Bad cell count for /nor@70009000/bus@0
Got it to work if I changed to (also had to add an empty ranges prop
in bus node):
gmi@70009000 {
#address-cells = <1>;
#size-cells = <1>;
ranges;
bus@0,0 {
compatible = "simple-bus";
reg = <0 0>;
ranges;
#address-cells = <1>;
#size-cells = <1>;
can@48000000 {
reg = <0x48000000 0x100>;
...
};
can@48040000 {
reg = <0x48040000 0x100>;
...
};
}
But I wonder is there something wrong with below example (which does
work), that is omitting the bus node:
gmi@70009000 {
#address-cells = <1>;
#size-cells = <1>;
ranges;
can@48000000 {
reg = <0x48000000 0x100>;
...
};
can@48040000 {
reg = <0x48040000 0x100>;
...
};
}
Just feel that I need to duplicate information if add an bus node.
Best Regards,
Mirza
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