AM335x: Assigning interrupt to a GPIO via DTS

For reference, this is what I have added so far. I added this right after the uart definitions in the am33xx.dtsi. The duart is at address ox01000000 (CS1).

        uart6: serial@01000000 {
            device_type = "serial";
            compatible = "ns16550";
            ti,hwmods = "uart7";
            clock-frequency = <7372800>;
            reg = <0x01000000 0x8>;
            interrupt-parent = <&gpio3>;
            interrupts = <17 1>;
            status = "disabled";
        };

I did not touch the gpio3 node, but here it is below in case something needs to be changed:

        gpio3: gpio@481ae000 {
            compatible = "ti,omap4-gpio";
            ti,hwmods = "gpio4";
            gpio-controller;
            #gpio-cells = <2>;
            interrupt-controller;
            #interrupt-cells = <2>;
            reg = <0x481ae000 0x1000>;
            interrupts = <62>;
        };

For configuring the interrupt as active low level-sensitive, you need to set the second cell of the "interrupts" member to 0x8. For more information about this, read <kernel_dir>/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt.

Another useful reading: http://www.devicetree.org/Device_Tree_Usage#How_Interrupts_Work

Best regards,
Miroslav

Thanks Miroslav. I have read the documents you mentioned. Still a few things that Im a bit unclear on. For uart0, the linux console, I also see the following in am335x-bone-common:

    uart0_pins: pinmux_uart0_pins {
        pinctrl-single,pins = <
            0x170 (PIN_INPUT_PULLUP | MUX_MODE0)    /* uart0_rxd.uart0_rxd */
            0x174 (PIN_OUTPUT_PULLDOWN | MUX_MODE0)    /* uart0_txd.uart0_txd */
        >;
    };

and:

&uart0 {
    pinctrl-names = "default";
    pinctrl-0 = <&uart0_pins>;

    status = "okay";
};

It appears that these sections are needed since uart0 uses tx/rx pins straight off the processor. For an external uart, can I omit these sections completely? Seems that I can definitely omit "uart0_pins: pinmux_uart0_pins" node. But should I keep the "&uart0" node since it contains the line:

status = "okay"

In my uart6 node in the original post the status is set to status = "disabled", so Im wondering if I need this status = "okay" somewhere in the dts to enable the port.

Also, is there any easy way to know how my new serial port will look in the /dev directory once linux boots? Just want to know what to look for to see if my serial port is there. My kernel boots with the linux console at /dev/ttyO0. There is also /dev/ttyS0-S3. Not sure where these are coming from.

Thanks for your help - Anthony

As far as I can see in the documentation, the "status" property is used to check if a device is ready for use. Check here: http://lxr.free-electrons.com/source/drivers/of/base.c?v=3.12#L395

/**
 *  __of_device_is_available - check if a device is available for use
 *
 *  @device: Node to check for availability, with locks already held
 *
 *  Returns 1 if the status property is absent or set to "okay" or "ok",
 *  0 otherwise
 */
static int __of_device_is_available(const struct device_node *device)
{
    const char *status;
    int statlen;

    status = __of_get_property(device, "status", &statlen);
    if (status == NULL)
        return 1;

    if (statlen > 0) {
        if (!strcmp(status, "okay") || !strcmp(status, "ok"))
            return 1;
    }

    return 0;
}

My knowledge on your second question is limited, sorry.

Best regards,
Miroslav