Hi Hans,
On Sun, Dec 12, 2021 at 01:42:38PM +0100, Hans de Goede wrote:
> Add a new helper function to copy absinfo from one input_dev to
> another input_dev.
>
> This is useful to e.g. setup a pen/stylus input-device for combined
> touchscreen/pen hardware where the pen uses the same coordinates as
> the touchscreen.
>
> Suggested-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/input/input.c | 34 ++++++++++++++++++++++++++++++++++
> include/linux/input.h | 2 ++
> 2 files changed, 36 insertions(+)
>
> diff --git a/drivers/input/input.c b/drivers/input/input.c
> index ccaeb2426385..60f3eb38906f 100644
> --- a/drivers/input/input.c
> +++ b/drivers/input/input.c
> @@ -526,6 +526,40 @@ void input_set_abs_params(struct input_dev *dev, unsigned int axis,
> }
> EXPORT_SYMBOL(input_set_abs_params);
>
> +/**
> + * input_copy_abs - Copy absinfo from one input_dev to another
> + * @dst: Destination input device to copy the abs settings to
> + * @dst_axis: ABS_* value selecting the destination axis
> + * @src: Source input device to copy the abs settings from
> + * @src_axis: ABS_* value selecting the source axis
> + *
> + * Set absinfo for the selected destination axis by copying it from
> + * the specified source input device's source axis.
> + * This is useful to e.g. setup a pen/stylus input-device for combined
> + * touchscreen/pen hardware where the pen uses the same coordinates as
> + * the touchscreen.
> + */
> +void input_copy_abs(struct input_dev *dst, unsigned int dst_axis,
> + const struct input_dev *src, unsigned int src_axis)
> +{
> + /*
> + * input_alloc_absinfo() may have failed for the source. Our caller is
> + * expected to catch this when registering the input devices, which may
> + * happen after the input_copy_abs() call.
> + */
> + if (!src->absinfo)
> + return;
I'd probably check if source device actually declared EV_ABS/src_axis
and yelled loudly (WARN?) in such case.
> +
> + input_alloc_absinfo(dst);
> + if (!dst->absinfo)
> + return;
> +
> + dst->absinfo[dst_axis] = src->absinfo[src_axis];
> +
> + __set_bit(EV_ABS, dst->evbit);
> + __set_bit(dst_axis, dst->absbit);
input_set_capability() ?
> +}
> +EXPORT_SYMBOL(input_copy_abs);
Thanks.
--
Dmitry
