[RFC 1/2] input: mt: Add method to extract the MT slot state

[Benjamin Tissoires]

This patch adds the function input_mt_get_abs_value(), which may be
used to extract the current state of the MT slots.

Signed-off-by: Henrik Rydberg <rydberg@xxxxxxxxxxx>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxx>
---
 drivers/input/input-mt.c |   32 ++++++++++++++++++++++++++++++++
 include/linux/input/mt.h |    1 +
 2 files changed, 33 insertions(+), 0 deletions(-)

diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c
index c48c81f..5b95e38 100644
--- a/drivers/input/input-mt.c
+++ b/drivers/input/input-mt.c
@@ -168,3 +168,35 @@ void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
 	}
 }
 EXPORT_SYMBOL(input_mt_report_pointer_emulation);
+
+/**
+ * input_mt_get_absinfo - retrieve MT state variables from a device slot
+ * @dev: input device which state is being queried
+ * @code: ABS code to retrieve
+ * @slot: slot to retrieve from
+ *
+ * Return the ABS state of the given MT slot. If code is not an MT
+ * event, the corresponding ABS event is returned.
+ *
+ * This function may be called by anyone interested in extracting the
+ * current MT state. Used by evdev handlers.
+ */
+struct input_absinfo input_mt_get_absinfo(struct input_dev *dev, unsigned int code, int slot)
+{
+	unsigned int mtmap = code > ABS_MT_FIRST ? code - ABS_MT_FIRST : 0;
+	unsigned long flags;
+	struct input_absinfo retval;
+
+	spin_lock_irqsave(&dev->event_lock, flags);
+	if (!mtmap)
+		retval = dev->absinfo[code];
+	else if (slot >= 0 && slot < dev->mtsize) {
+		retval = dev->absinfo[code];
+		retval.value = dev->mt[slot].abs[mtmap];
+	} else
+		retval.value = 0;
+	spin_unlock_irqrestore(&dev->event_lock, flags);
+
+	return retval;
+}
+EXPORT_SYMBOL(input_mt_get_absinfo);
diff --git a/include/linux/input/mt.h b/include/linux/input/mt.h
index b3ac06a..a71a27f 100644
--- a/include/linux/input/mt.h
+++ b/include/linux/input/mt.h
@@ -54,4 +54,5 @@ void input_mt_report_slot_state(struct input_dev *dev,
 void input_mt_report_finger_count(struct input_dev *dev, int count);
 void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count);
 
+struct input_absinfo input_mt_get_absinfo(struct input_dev *dev, unsigned int code, int slot);
 #endif
-- 
1.7.3.4

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