On Mon, May 14 2018, Sergio Paracuellos wrote:

> This commit add missing dt bindings documentation for mt7621-gpio
> driver. After this checkpatch script complain about this
> issue dissapears.
>
> Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
> ---
>  .../devicetree/bindings/gpio/mtk,mt7621-gpio.txt   | 51 ++++++++++++++++++++++
>  1 file changed, 51 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/gpio/mtk,mt7621-gpio.txt
>
> diff --git a/Documentation/devicetree/bindings/gpio/mtk,mt7621-gpio.txt b/Documentation/devicetree/bindings/gpio/mtk,mt7621-gpio.txt
> new file mode 100644
> index 0000000..5fe4bb5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/mtk,mt7621-gpio.txt
> @@ -0,0 +1,51 @@
> +Mediatek SoC GPIO controller bindings
> +
> +The IP core used inside these SoCs has 3 banks of 32 GPIOs each.
> +The registers of all the banks are interwoven inside one single IO range.
> +We load one GPIO controller instance per bank. To make this possible
> +we support 2 types of nodes. The parent node defines the memory I/O range and
> +has 3 children each describing a single bank.
> +
> +Required properties for the top level node:
> +- compatible:
> +  - "mtk,mt7621-gpio" for Mediatek controllers
> +- reg : Physical base address and length of the controller's registers
> +
> +Required properties for the GPIO bank node:
> +- compatible:
> +  - "mtk,mt7621-gpio-bank" for Mediatek banks
> +- #gpio-cells : Should be two.
> +  - first cell is the pin number
> +  - second cell is used to specify optional parameters (unused)
> +- gpio-controller : Marks the device node as a GPIO controller
> +- reg : The id of the bank that the node describes.

This is really good, but not quite complete.
Searching for "of_" in gpio-mt7621.c I find code handling everything
you've described, but also:

	mediatek_gpio_irq = irq_of_parse_and_map(np, 0);
	if (mediatek_gpio_irq) {
		mediatek_gpio_irq_domain = irq_domain_add_linear(np,

The GPIO controller can receive interrupts on any of the GPIOs,
either edge or level.  It then interrupts the CPU using GIC INT12.

so
    interrupt-parent = <&gic>;
    interrupts = <GIC_SHARED 12 IRQ_TYPE_LEVEL_HIGH>
(I think).
Then you need whatever irq_domain_add_linear() expects.
I don't know what that is...  I tried following through
code and got lost in little twisty mazes.

So if you change this patch to add the file to
drivers/staging/mt7621-gpio
then I can give it
  Reviewed-by: NeilBrown <neil@brown.name>

and then we can fix it when an understanding of the interrupts is
available.
But I cannot approve it for Documentation/devicetree/bindings yet.

Thanks a lot,
NeilBrown


> +
> +Example:
> +	gpio@600 {
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		compatible = "mtk,mt7621-gpio";
> +		reg = <0x600 0x100>;
> +
> +		gpio0: bank@0 {
> +			reg = <0>;
> +			compatible = "mtk,mt7621-gpio-bank";
> +			gpio-controller;
> +			#gpio-cells = <2>;
> +		};
> +
> +		gpio1: bank@1 {
> +			reg = <1>;
> +			compatible = "mtk,mt7621-gpio-bank";
> +			gpio-controller;
> +			#gpio-cells = <2>;
> +		};
> +
> +		gpio2: bank@2 {
> +			reg = <2>;
> +			compatible = "mtk,mt7621-gpio-bank";
> +			gpio-controller;
> +			#gpio-cells = <2>;
> +		};
> +	};
> -- 
> 2.7.4