2016-07-25 16:15 GMT+02:00 Thierry Reding [off-list ref]:

On Mon, Jul 25, 2016 at 03:16:28PM +0200, Mirza Krak wrote:

quoted

2016-07-25 13:30 GMT+02:00 Thierry Reding [off-list ref]:

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 at 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 at 0 {
                        compatible = "simple-bus";
                        reg = <0>;

                        #address-cells = <1>;
                        #size-cells = <1>;

                        can at 48000000 {
                                reg = <0x48000000 0x100>;
                                ...
                        };

                        can at 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 at 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 at 70009000/bus at 0

Got it to work if I changed to (also had to add an empty ranges prop
in bus node):

gmi at 70009000 {
    #address-cells = <1>;
    #size-cells = <1>;
    ranges;

    bus at 0,0 {
                compatible = "simple-bus";
                reg = <0 0>;
                ranges;

                #address-cells = <1>;
                #size-cells = <1>;

                can at 48000000 {
                    reg = <0x48000000 0x100>;
                    ...
                };


                can at 48040000 {
                    reg = <0x48040000 0x100>;
                    ...
                };
}

But I wonder is there something wrong with below example (which does
work), that is omitting the bus node:

gmi at 70009000 {
    #address-cells = <1>;
    #size-cells = <1>;
    ranges;

    can at 48000000 {
        reg = <0x48000000 0x100>;
        ...
    };

    can at 48040000 {
        reg = <0x48040000 0x100>;
        ...
    };
}

Just feel that I need to duplicate information if add an bus node.

Best Regards,
Mirza