On 31/08/16 12:22, Mirza Krak wrote:

2016-08-30 19:06 GMT+02:00 Rob Herring [off-list ref]:

...

quoted

quoted

                 nvidia,snor-cs = <4>;

NAK, no custom CS properties.

Ok, so ...

gmi at 70090000 {
        compatible = "nvidia,tegra20-gmi";
        reg = <0x70009000 0x1000>;
        #address-cells = <2>;
        #size-cells = <1>;
        clocks = <&tegra_car TEGRA20_CLK_NOR>;
        clock-names = "gmi";
        resets = <&tegra_car 42>;
        reset-names = "gmi";
        ranges = <4 0 0xd0000000 0xfffffff>;

        status = "okay";

        bus at 4,0 {
                compatible = "simple-bus";
                #address-cells = <1>;
                #size-cells = <1>;
                ranges = <0 4 0 0x40000>;

                nvidia,snor-mux-mode;
                nvidia,snor-adv-inv;

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

                can at 40000 {
                        reg = <0x40000 0x100>;
                        ...
                };
        };
};

Have I understood you correct?

Also wanted to verify the example case where you only have on device
connected to one CS#, from what I see in other implementations it
seems OK to put the CS# in the reg property in that case. Is this
correct?

Example with one SJA1000 CAN controller connected to the GMI bus
on CS4:

gmi at 70090000 {
        compatible = "nvidia,tegra20-gmi";
        reg = <0x70009000 0x1000>;
        #address-cells = <2>;
        #size-cells = <1>;
        clocks = <&tegra_car TEGRA20_CLK_NOR>;
        clock-names = "gmi";
        resets = <&tegra_car 42>;
        reset-names = "gmi";
        ranges = <4 0 0xd0000000 0xfffffff>;

        status = "okay";

        can at 4,0 {
                reg = <4 0 0x100>;
                nvidia,snor-mux-mode;
                nvidia,snor-adv-inv;
                ...
        };
};

Jon, to be able to handle both cases in the driver we would first
attempt to decode the CS# from the ranges property, and fallback to
reg property if no ranges are defined. Does that sound reasonable?

Given the above examples that may be supported, is there a
better/simpler way to extract the CS# than what Mirza is proposing? For
example, from the node-name unit-address?

Cheers
Jon

-- 
nvpublic