Re: [PATCHv2 4/4] Input: rotary-encoder - Add gpio as push button

[Rob Herring <robh@kernel.org>]

On Mon, Sep 07, 2020 at 10:40:45PM +0200, Sebastian Reichel wrote:
> From: Mylène Josserand <mylene.josserand@collabora.com>
> 
> Add the support of a gpio that can be defined as a push button.
> Thanks to that, it is possible to emit a keycode in case of a
> "push" event, if the rotary supports that.
> 
> The keycode to emit is defined using "linux,code" property
> (such as in gpio-keys).

But it is not...

> Signed-off-by: Mylène Josserand <mylene.josserand@collabora.com>
> [code cleanup to current standards and renamed some properties]
> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
> ---
>  .../bindings/input/rotary-encoder.yaml        | 21 +++++++++

Bindings should be a separate patch.

>  drivers/input/misc/rotary_encoder.c           | 43 +++++++++++++++++++
>  2 files changed, 64 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/input/rotary-encoder.yaml b/Documentation/devicetree/bindings/input/rotary-encoder.yaml
> index 5b60ea86bd62..682fee104004 100644
> --- a/Documentation/devicetree/bindings/input/rotary-encoder.yaml
> +++ b/Documentation/devicetree/bindings/input/rotary-encoder.yaml
> @@ -74,6 +74,24 @@ properties:
>        need to be passed.
>      type: boolean
>  
> +  push-gpios:
> +    description: GPIO used as a detection of a push from the rotary-encoder.
> +    maxItems: 1
> +
> +  linux,push-code:
> +    description:
> +      keycode to emit with the push-gpio of this rotary encoder.
> +      If not specified defaults to <28> == KEY_ENTER.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    default: 28
> +
> +  linux,push-type:
> +    description:
> +      Specify event type this button/key generates.
> +      If not specified defaults to <1> == EV_KEY.
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    default: 1

Can we just use 'linux,code' and 'linux,input-type' here. That's 
problematic if there's ever more than 1, but so is the current solution 
having to make up new property names every time.

Why can't the gpio-keys binding just be used here? Is it important to 
have the events on the same device? Is there some coordination needed 
between the functions?

> +
>  required:
>    - compatible
>    - gpios
> @@ -97,4 +115,7 @@ examples:
>              linux,axis = <ABS_Y>;
>              rotary-encoder,encoding = "binary";
>              rotary-encoder,rollover;
> +            push-gpios = <&gpio 23 GPIO_ACTIVE_HIGH>;
> +            linux,push-code = <KEY_ENTER>;
> +            linux,push-type = <EV_KEY>;
>      };
> diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
> index 16ad86fad7cb..484042a5afa0 100644
> --- a/drivers/input/misc/rotary_encoder.c
> +++ b/drivers/input/misc/rotary_encoder.c
> @@ -47,12 +47,33 @@ struct rotary_encoder {
>  
>  	unsigned int *irq;
>  
> +	struct gpio_desc *push_gpio;
> +	unsigned int push_code;
> +	unsigned int push_type;
> +
>  	bool armed;
>  	signed char dir;	/* 1 - clockwise, -1 - CCW */
>  
>  	unsigned int last_stable;
>  };
>  
> +static irqreturn_t rotary_push_irq(int irq, void *dev_id)
> +{
> +	struct rotary_encoder *encoder = dev_id;
> +	int val;
> +
> +	mutex_lock(&encoder->access_mutex);
> +
> +	val = gpiod_get_value_cansleep(encoder->push_gpio);
> +
> +	input_report_key(encoder->input, encoder->push_code, val);
> +	input_sync(encoder->input);
> +
> +	mutex_unlock(&encoder->access_mutex);
> +
> +	return IRQ_HANDLED;
> +}
> +
>  static unsigned int rotary_encoder_get_state(struct rotary_encoder *encoder)
>  {
>  	int i;
> @@ -248,6 +269,16 @@ static int rotary_encoder_probe(struct platform_device *pdev)
>  		return -EINVAL;
>  	}
>  
> +	encoder->push_gpio = devm_gpiod_get_optional(dev, "push", GPIOD_IN);
> +	if (IS_ERR(encoder->push_gpio))
> +		return dev_err_probe(dev, PTR_ERR(encoder->push_gpio), "failed to get push-gpio\n");
> +
> +	encoder->push_code = KEY_ENTER;
> +	device_property_read_u32(dev, "linux,push-code", &encoder->push_code);
> +
> +	encoder->push_type = EV_KEY;
> +	device_property_read_u32(dev, "linux,push-type", &encoder->push_type);
> +
>  	input = devm_input_allocate_device(dev);
>  	if (!input)
>  		return -ENOMEM;
> @@ -304,6 +335,18 @@ static int rotary_encoder_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> +	if (encoder->push_gpio) {
> +		input_set_capability(encoder->input, encoder->push_type, encoder->push_code);
> +		err = devm_request_threaded_irq(dev, gpiod_to_irq(encoder->push_gpio),
> +						NULL, rotary_push_irq,
> +						IRQF_TRIGGER_RISING |
> +						IRQF_TRIGGER_FALLING |
> +						IRQF_ONESHOT,
> +						DRV_NAME, encoder);
> +		if (err)
> +			return dev_err_probe(dev, err, "unable to request push IRQ\n");
> +	}
> +
>  	err = input_register_device(input);
>  	if (err) {
>  		dev_err(dev, "failed to register input device\n");
> -- 
> 2.28.0
>