[v2,1/2] devicetree: bindings: Update gpio-keys-polled with support for abs/rel axis

The devicetree binding for gpio-keys-polled already allows specifying
what type of events (key / rel / abs) a button generates when pressed.

But for rel / abs axis we also need to specify which value this specific
gpio represents.

One usecase is digital joysticks / direction-pads which are hooked up to
gpio, in this case we've left and right buttons which we want to map to
EV_ABS, ABS_X and we want generate events for left with a value of -1 and
for right with a value of +1 (and similar for up / down and ABS_Y).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Rob Herring <robh@kernel.org>
---
Changes in v2:
-Add Rob's ack
-s/send/sent/
-Make the remarks of axis reporting a value of 0 when all buttons tied to
 that axis are released also apply to EV_REL axis
---
 Documentation/devicetree/bindings/input/gpio-keys-polled.txt | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

On Thu, Sep 17, 2015 at 06:14:40PM -0400, Hans de Goede wrote:
> Add support for EV_ABS / EV_REL events to the gpio-keys-polled driver.
> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
> Changes in v2:
> -Fix commit message to actually describe what the patch does
>  (fix patch squashing fail)
> ---
>  drivers/input/keyboard/gpio_keys_polled.c | 88 +++++++++++++++++++++++++++----
>  1 file changed, 79 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/input/keyboard/gpio_keys_polled.c b/drivers/input/keyboard/gpio_keys_polled.c
> index 870cfa6..62bdb1d 100644
> --- a/drivers/input/keyboard/gpio_keys_polled.c
> +++ b/drivers/input/keyboard/gpio_keys_polled.c
> @@ -40,10 +40,36 @@ struct gpio_keys_polled_dev {
>  	struct input_polled_dev *poll_dev;
>  	struct device *dev;
>  	const struct gpio_keys_platform_data *pdata;
> +	unsigned long rel_axis_seen[BITS_TO_LONGS(REL_CNT)];
> +	unsigned long abs_axis_seen[BITS_TO_LONGS(ABS_CNT)];
>  	struct gpio_keys_button_data data[0];
>  };
>  
> -static void gpio_keys_polled_check_state(struct input_dev *input,
> +static void gpio_keys_button_event(struct input_polled_dev *dev,
> +				   struct gpio_keys_button *button,
> +				   int state)
> +{
> +	struct gpio_keys_polled_dev *bdev = dev->private;
> +	struct input_dev *input = dev->input;
> +	unsigned int type = button->type ?: EV_KEY;
> +
> +	if (type == EV_REL) {
> +		if (state) {
> +			input_event(input, type, button->code, button->value);
> +			__set_bit(button->code, bdev->rel_axis_seen);
> +		}
> +	} else if (type == EV_ABS) {
> +		if (state) {
> +			input_event(input, type, button->code, button->value);
> +			__set_bit(button->code, bdev->abs_axis_seen);
> +		}
> +	} else {
> +		input_event(input, type, button->code, state);
> +		input_sync(input);
> +	}
> +}
> +
> +static void gpio_keys_polled_check_state(struct input_polled_dev *dev,
>  					 struct gpio_keys_button *button,
>  					 struct gpio_keys_button_data *bdata)
>  {
> @@ -54,11 +80,9 @@ static void gpio_keys_polled_check_state(struct input_dev *input,
>  	else
>  		state = !!gpiod_get_value(button->gpiod);
>  
> -	if (state != bdata->last_state) {
> -		unsigned int type = button->type ?: EV_KEY;
> +	gpio_keys_button_event(dev, button, state);
>  
> -		input_event(input, type, button->code, state);
> -		input_sync(input);
> +	if (state != bdata->last_state) {
>  		bdata->count = 0;
>  		bdata->last_state = state;
>  	}
> @@ -71,15 +95,33 @@ static void gpio_keys_polled_poll(struct input_polled_dev *dev)
>  	struct input_dev *input = dev->input;
>  	int i;
>  
> +	memset(bdev->rel_axis_seen, 0, sizeof(bdev->rel_axis_seen));
> +	memset(bdev->abs_axis_seen, 0, sizeof(bdev->abs_axis_seen));
> +
>  	for (i = 0; i < pdata->nbuttons; i++) {
>  		struct gpio_keys_button_data *bdata = &bdev->data[i];
>  
> -		if (bdata->count < bdata->threshold)
> +		if (bdata->count < bdata->threshold) {
>  			bdata->count++;
> -		else
> -			gpio_keys_polled_check_state(input, &pdata->buttons[i],
> +			gpio_keys_button_event(dev, &pdata->buttons[i],
> +					       bdata->last_state);
> +		} else {
> +			gpio_keys_polled_check_state(dev, &pdata->buttons[i],
>  						     bdata);
> +		}
> +	}
> +
> +	for_each_set_bit(i, input->relbit, REL_CNT) {
> +		if (!test_bit(i, bdev->rel_axis_seen))
> +			input_event(input, EV_REL, i, 0);
> +	}

I wonder if this should be written as

	for_each_set_bit(i, bdev->rel_axis_seen, REL_CNT)
		input_event(input, EV_REL, i, 0);

i.e. the 2nd bit test is not really needed because we should not see
unsupported bits in "seen" axes.

> +
> +	for_each_set_bit(i, input->absbit, ABS_CNT) {
> +		if (!test_bit(i, bdev->abs_axis_seen))
> +			input_event(input, EV_ABS, i, 0);
>  	}
> +
> +	input_sync(input);
>  }
>  
>  static void gpio_keys_polled_open(struct input_polled_dev *dev)
> @@ -152,6 +194,10 @@ static struct gpio_keys_platform_data *gpio_keys_polled_get_devtree_pdata(struct
>  					     &button->type))
>  			button->type = EV_KEY;
>  
> +		if (fwnode_property_read_u32(child, "linux,input-value",
> +					     (u32 *)&button->value))
> +			button->value = 1;

Umm, we need negative values too... but there is no
fwnode_property_read_s32 :(. We need to document in the bindings that
value is treated as signed so that users can still achieve the needed
effect.

> +
>  		button->wakeup =
>  			fwnode_property_read_bool(child, "wakeup-source") ||
>  			/* legacy name */
> @@ -168,6 +214,25 @@ static struct gpio_keys_platform_data *gpio_keys_polled_get_devtree_pdata(struct
>  	return pdata;
>  }
>  
> +static void gpio_keys_polled_set_abs_params(struct input_dev *input,
> +	const struct gpio_keys_platform_data *pdata, unsigned int code)
> +{
> +	int i, min = 0, max = 0;
> +
> +	for (i = 0; i < pdata->nbuttons; i++) {
> +		struct gpio_keys_button *button = &pdata->buttons[i];
> +
> +		if (button->type != EV_ABS || button->code != code)
> +			continue;
> +
> +		if (button->value < min)
> +			min = button->value;
> +		if (button->value > max)
> +			max = button->value;
> +	}
> +	input_set_abs_params(input, code, min, max, 0, 0);
> +}
> +
>  static const struct of_device_id gpio_keys_polled_of_match[] = {
>  	{ .compatible = "gpio-keys-polled", },
>  	{ },
> @@ -274,6 +339,9 @@ static int gpio_keys_polled_probe(struct platform_device *pdev)
>  						pdata->poll_interval);
>  
>  		input_set_capability(input, type, button->code);
> +		if (type == EV_ABS)
> +			gpio_keys_polled_set_abs_params(input, pdata,
> +							button->code);
>  	}
>  
>  	bdev->poll_dev = poll_dev;
> @@ -290,9 +358,11 @@ static int gpio_keys_polled_probe(struct platform_device *pdev)
>  
>  	/* report initial state of the buttons */
>  	for (i = 0; i < pdata->nbuttons; i++)
> -		gpio_keys_polled_check_state(input, &pdata->buttons[i],
> +		gpio_keys_polled_check_state(poll_dev, &pdata->buttons[i],
>  					     &bdev->data[i]);
>  
> +	input_sync(input);
> +
>  	return 0;
>  }
>  
> -- 
> 2.4.3
> 

Thanks.