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;
+
+ 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);
+}
+EXPORT_SYMBOL(input_copy_abs);
/**
* input_grab_device - grabs device for exclusive use
diff --git a/include/linux/input.h b/include/linux/input.h
index 0354b298d874..49790c1bd2c4 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -475,6 +475,8 @@ static inline void input_set_events_per_packet(struct input_dev *dev, int n_even
void input_alloc_absinfo(struct input_dev *dev);
void input_set_abs_params(struct input_dev *dev, unsigned int axis,
int min, int max, int fuzz, int flat);
+void input_copy_abs(struct input_dev *dst, unsigned int dst_axis,
+ const struct input_dev *src, unsigned int src_axis);
#define INPUT_GENERATE_ABS_ACCESSORS(_suffix, _item) \
static inline int input_abs_get_##_suffix(struct input_dev *dev, \
--
2.33.1
