Re: [PATCH v4 1/4] dt-bindings: gpio: spacemit: add support for K1 SoC

Olof Johansson
2025-01-22T20:06:48Z

Hi,

On Tue, Jan 21, 2025 at 11:38:11AM +0800, Yixun Lan wrote:
> The GPIO controller of K1 support basic functions as input/output,
> all pins can be used as interrupt which route to one IRQ line,
> trigger type can be select between rising edge, failing edge, or both.
> There are four GPIO ports, each consisting of 32 pins.
>
> Signed-off-by: Yixun Lan <dlan@gentoo.org>
> ---
> .../devicetree/bindings/gpio/spacemit,k1-gpio.yaml | 116 +++++++++++++++++++++
> 1 file changed, 116 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/gpio/spacemit,k1-gpio.yaml b/Documentation/devicetree/bindings/gpio/spacemit,k1-gpio.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..dd9459061aecfcba84e6a3c5052fbcddf6c61150
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/spacemit,k1-gpio.yaml
> @@ -0,0 +1,116 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/gpio/spacemit,k1-gpio.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: SpacemiT K1 GPIO controller
> +
> +maintainers:
> + - Yixun Lan <dlan@gentoo.org>
> +
> +description:
> + The controller's registers are organized as sets of eight 32-bit
> + registers with each set of port controlling 32 pins. A single
> + interrupt line is shared for all of the pins by the controller.
> + Each port will be represented as child nodes with the generic
> + GPIO-controller properties in this bindings file.

There's only one interrupt line for all ports, but you have a binding that
duplicates them for every set of ports. That seems overly complicated,
doesn't it? They'd all bind the same handler, so there's no benefit in
providing the flexibility,.

> +properties:
> + $nodename:
> + pattern: "^gpio@[0-9a-f]+$"
> +
> + compatible:
> + const: spacemit,k1-gpio
> +
> + reg:
> + maxItems: 1
> +
> + "#address-cells":
> + const: 1
> +
> + "#size-cells":
> + const: 0
> +
> +patternProperties:
> + "^gpio-port@[0-9a-f]+$":
> + type: object
> + properties:
> + compatible:
> + const: spacemit,k1-gpio-port
> +
> + reg:
> + maxItems: 1
> +
> + gpio-controller: true
> +
> + "#gpio-cells":
> + const: 2
> +
> + gpio-ranges: true
> +
> + interrupts:
> + maxItems: 1
> +
> + interrupt-controller: true
> +
> + "#interrupt-cells":
> + const: 2
> + description:
> + The first cell is the GPIO number, the second should specify interrupt
> + flag. The controller does not support level interrupts, so flags of
> + IRQ_TYPE_LEVEL_HIGH, IRQ_TYPE_LEVEL_LOW should not be used.
> + Refer <dt-bindings/interrupt-controller/irq.h> for valid flags.

Same here, since there's no real flexibility between the banks, it might
make sense to consider a 3-cell GPIO specifier instead, and having
the first cell indicate bank. I could see this argument go in either
direction, but I'm not sure I understand why to provide a gpio-controller
per bank.

Comparing to say Rockchip, where each bank has a separate interrupt line
-- so there the granularity makes sense.

-Olof