SK-AM62P-LP: Configure pin WKUP_CLKOUT0 with clock 32768Hz

Mark Corbin

Part Number: SK-AM62P-LP
Other Parts Discussed in Thread: AM62P

Tool/software:

Hello

I'm trying to configure the WKUP_CLKOUT0 pin to output 32KHz instead of 25MHz. This is for an external WiFi module connected via an M.2 interface. The processor on our board is an AM6232A.

I have the following device tree section...

&sdhci2 {
        boot-ph-all;
        pinctrl-names = "default";
        pinctrl-0 = <&wifi_pins_default
                     &wifi_32k_clk_pins_default>;
        status = "okay";
        vmmc-supply = <&vdd_3v3>;
      vqmmc-supply = <&buck2_reg>;
        mmc-pwrseq = <&wifi_pwrseq>;
        bus-width = <4>;
        non-removable;
        ti,fails-without-test-cd;
        keep-power-in-suspend;
        ti,driver-strength-ohm = <50>;
        max-frequency = <50000000>;
        cap-power-off-card;

        #address-cells = <1>;
        #size-cells = <0>;
        wlcore: wlcore@2 {
                compatible = "ti,cc33xx";
                reg = <2>;
                pinctrl-names = "default";
                pinctrl-0 = <&wifi_irq_pins_default>;
                interrupt-parent = <&main_gpio0>;
                interrupts = <71 IRQ_TYPE_EDGE_FALLING>;
        };
};

...but can't work out what I need to add for 'assigned-clocks'.

I've found this in the TRM...

and this from software-dl.ti.com/.../clocks.html

We have a 32.768KHz crystal connected externally across the WKUP_LFOSC0_X... pins.

How do I configure my DTS file to route the LFOSC0 clock to the WKUP_CLKOUT0 pin?

Thanks

Mark

6 months ago

0 Anshu Madwesh 6 months ago

TI__Mastermind 18590 points

Hello Mark,

Can you confirm which device you are using? AM62x or AM62P? The clocking architecture is slightly different for each device.

The Clock Tree Tool will be useful to use to use: https://dev.ti.com/sysconfig/#/start

Just select AM6x Clock Tree and the device you are using. WKUP_CLKOUT0 is under Device Configuration > Clock Outputs > WKUP_CLKOUT0.

You can change the WKUP_CLKOUT_SEL register to change which one to use by clicking on the UI. See the register diff at the bottom to see what changed. You can write to a register in Linux using devmem2.

Lets test if this works. You can use K3Conf to dump the clock output ('k3conf dump clocks | grep WKUP_CLKOUT0' is what I used).

I'm not sure how this is done in the device tree, but I'll look into it.

Best Regards,

Anshu

0 Mark Corbin 6 months ago in reply to Anshu Madwesh

Prodigy 60 points

The device part number is AM6232A-SCGHAALW

+1 Anshu Madwesh 6 months ago in reply to Mark Corbin

TI__Mastermind 18590 points

Hi Mark,

Refer to the k3-am625-beagleplay.dts device tree: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts?h=ti-linux-6.6.y#n863

In this node, there is an assigned clock of 158 as the input and then sets the parent to 160: https://downloads.ti.com/tisci/esd/latest/5_soc_doc/am62x/clocks.html#clocks-for-board0-device

Best Regards,

Anshu

0 Mark Corbin 6 months ago in reply to Anshu Madwesh

Prodigy 60 points

Hello Anshu

I can confirm that adding the following worked for me.

assigned-clocks = <&k3_clks 157 158>;
assigned-clock-parents = <&k3_clks 157 160>;

Thanks for your help.

Regards

Mark

0 Anshu Madwesh 6 months ago in reply to Mark Corbin

TI__Mastermind 18590 points

Thanks for the update Mark. This thread will be closed. Feel free to make another post for additional questions.

Thanks,

Anshu

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SK-AM62P-LP: Configure pin WKUP_CLKOUT0 with clock 32768Hz