linux-kernel - Re: [PATCH v2 2/4] Input: adc-keys - support EV_SW as well, not just EV

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Message-ID: <202512160845594c145070@mail.local>
Date: Tue, 16 Dec 2025 09:45:59 +0100
From: Alexandre Belloni <alexandre.belloni@...tlin.com>
To: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Heiko Stuebner <heiko@...ech.de>, kernel@...labora.com,
	linux-input@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH v2 2/4] Input: adc-keys - support EV_SW as well, not just
 EV_KEY.

On 15/12/2025 13:29:30+0100, Nicolas Frattaroli wrote:
> Instead of doing something like what gpio-keys is doing, adc-keys
> hardcodes that all keycodes must be of type EV_KEY.
> 
> This limits the usefulness of adc-keys, and overcomplicates the code
> with manual bit-setting logic.
> 
> Instead, refactor the code to read the linux,input-type fwnode property,
> and get rid of the custom bit setting logic, replacing it with
> input_set_capability instead. input_report_key is replaced with
> input_event, which allows us to explicitly pass the type.
> 
> Only EV_KEY and EV_SW is allowed at this stage.
> 
> Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>

Reviewed-by: Alexandre Belloni <alexandre.belloni@...tlin.com>

> ---
>  drivers/input/keyboard/adc-keys.c | 37 +++++++++++++++++++++++++------------
>  1 file changed, 25 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/input/keyboard/adc-keys.c b/drivers/input/keyboard/adc-keys.c
> index f1753207429d..62376f34f7d0 100644
> --- a/drivers/input/keyboard/adc-keys.c
> +++ b/drivers/input/keyboard/adc-keys.c
> @@ -18,13 +18,15 @@
>  
>  struct adc_keys_button {
>  	u32 voltage;
> -	u32 keycode;
> +	u32 code;
> +	u32 type;
>  };
>  
>  struct adc_keys_state {
>  	struct iio_channel *channel;
>  	u32 num_keys;
>  	u32 last_key;
> +	u32 last_type;
>  	u32 keyup_voltage;
>  	const struct adc_keys_button *map;
>  };
> @@ -34,7 +36,8 @@ static void adc_keys_poll(struct input_dev *input)
>  	struct adc_keys_state *st = input_get_drvdata(input);
>  	int i, value, ret;
>  	u32 diff, closest = 0xffffffff;
> -	int keycode = 0;
> +	u32 code = 0;
> +	u32 type = EV_KEY;
>  
>  	ret = iio_read_channel_processed(st->channel, &value);
>  	if (unlikely(ret < 0)) {
> @@ -45,22 +48,24 @@ static void adc_keys_poll(struct input_dev *input)
>  			diff = abs(st->map[i].voltage - value);
>  			if (diff < closest) {
>  				closest = diff;
> -				keycode = st->map[i].keycode;
> +				code = st->map[i].code;
> +				type = st->map[i].type;
>  			}
>  		}
>  	}
>  
>  	if (abs(st->keyup_voltage - value) < closest)
> -		keycode = 0;
> +		code = 0;
>  
> -	if (st->last_key && st->last_key != keycode)
> -		input_report_key(input, st->last_key, 0);
> +	if (st->last_key && st->last_key != code)
> +		input_event(input, st->last_type, st->last_key, 0);
>  
> -	if (keycode)
> -		input_report_key(input, keycode, 1);
> +	if (code)
> +		input_event(input, type, code, 1);
>  
>  	input_sync(input);
> -	st->last_key = keycode;
> +	st->last_key = code;
> +	st->last_type = type;
>  }
>  
>  static int adc_keys_load_keymap(struct device *dev, struct adc_keys_state *st)
> @@ -88,11 +93,20 @@ static int adc_keys_load_keymap(struct device *dev, struct adc_keys_state *st)
>  		map[i].voltage /= 1000;
>  
>  		if (fwnode_property_read_u32(child, "linux,code",
> -					     &map[i].keycode)) {
> +					     &map[i].code)) {
>  			dev_err(dev, "Key with invalid or missing linux,code\n");
>  			return -EINVAL;
>  		}
>  
> +		if (fwnode_property_read_u32(child, "linux,input-type",
> +					     &map[i].type))
> +			map[i].type = EV_KEY;
> +
> +		if (map[i].type != EV_KEY && map[i].type != EV_SW)
> +			return dev_err_probe(dev, -EINVAL,
> +					     "Invalid linux,input-type: 0x%x\n",
> +					     map[i].type);
> +
>  		i++;
>  	}
>  
> @@ -156,9 +170,8 @@ static int adc_keys_probe(struct platform_device *pdev)
>  	input->id.product = 0x0001;
>  	input->id.version = 0x0100;
>  
> -	__set_bit(EV_KEY, input->evbit);
>  	for (i = 0; i < st->num_keys; i++)
> -		__set_bit(st->map[i].keycode, input->keybit);
> +		input_set_capability(input, st->map[i].type, st->map[i].code);
>  
>  	if (device_property_read_bool(dev, "autorepeat"))
>  		__set_bit(EV_REP, input->evbit);
> 
> -- 
> 2.52.0
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com