Hi,

On 29 February 2016 at 09:56, Dinh Nguyen dinguyen@opensource.altera.com wrote:

Hi,

I have a few questions regarding the UCLASS_CLK driver. I need to implement a clock driver for a new-ish platform, an ARMv7 based SoCFPGA Arria10.

I think going forward, it would make sense to place the driver to be of UCLASS_CLK and would go into drivers/clk/, instead of under arch/arm/mach-socfpga directory, Am I correct in assuming that?

Yes.

My 2nd question is regarding the usage of uclass_get_device(UCLASS_CLK). If I have a DTS that is from: arch/arm/dts/socfpga.dtsi

Fragment of the clock portion from the DTS here:

clkmgr@ffd04000 { compatible = "altr,clk-mgr"; reg = <0xffd04000 0x1000>;

    clocks {
            #address-cells = <1>;
            #size-cells = <0>;

            osc1: osc1 {
                    #clock-cells = <0>;
                    compatible = "fixed-clock";
                    clock-frequency = <25000000>;

            };

            osc2: osc2 {
                    #clock-cells = <0>;
                    compatible = "fixed-clock";
            };

            f2s_periph_ref_clk: f2s_periph_ref_clk {
                    #clock-cells = <0>;
                    compatible = "fixed-clock";
            };

            f2s_sdram_ref_clk: f2s_sdram_ref_clk {
                    #clock-cells = <0>;
                    compatible = "fixed-clock";
            };

};

I tried calling uclass_get_device(UCLASS_CLK, 0, dev), thinking that it would return the "fixed-clock" clocks, then I can get the frequencies and move forward with calculating the rest of the clocks. But uclass_get_device() is returning an error for me. I'm sure I might have missed understood how the clock framework is supposed to work somewhere. Can you please point me in the right direction?

Do you have a driver for altr,clk-mgr? If not you could add a driver, or maybe "simple-bus" to the compatible string.

If you add a driver, see simple_bus_post_bind() for the function you need to call to bind devices in sub-nodes.

Regards, Simon