Input: Add EVIOC mechanism for MT slots
This patch adds the ability to extract MT slot data via a new ioctl,
EVIOCGMTSLOTS. The function returns an array of slot values for the
specified ABS_MT event type.
Example of user space usage:
struct { unsigned code; int values[64]; } req;
req.code = ABS_MT_POSITION_X;
if (ioctl(fd, EVIOCGMTSLOTS(sizeof(req)), &req) < 0)
return -1;
for (i = 0; i < 64; i++)
printf("slot %d: %d\n", i, req.values[i]);
Reviewed-by: Chase Douglas <chase.douglas@canonical.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
diff --git a/include/linux/input.h b/include/linux/input.h
index 3862e32..af26443 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -114,6 +114,31 @@
#define EVIOCGUNIQ(len) _IOC(_IOC_READ, 'E', 0x08, len) /* get unique identifier */
#define EVIOCGPROP(len) _IOC(_IOC_READ, 'E', 0x09, len) /* get device properties */
+/**
+ * EVIOCGMTSLOTS(len) - get MT slot values
+ *
+ * The ioctl buffer argument should be binary equivalent to
+ *
+ * struct input_mt_request_layout {
+ * __u32 code;
+ * __s32 values[num_slots];
+ * };
+ *
+ * where num_slots is the (arbitrary) number of MT slots to extract.
+ *
+ * The ioctl size argument (len) is the size of the buffer, which
+ * should satisfy len = (num_slots + 1) * sizeof(__s32). If len is
+ * too small to fit all available slots, the first num_slots are
+ * returned.
+ *
+ * Before the call, code is set to the wanted ABS_MT event type. On
+ * return, values[] is filled with the slot values for the specified
+ * ABS_MT code.
+ *
+ * If the request code is not an ABS_MT value, -EINVAL is returned.
+ */
+#define EVIOCGMTSLOTS(len) _IOC(_IOC_READ, 'E', 0x0a, len)
+
#define EVIOCGKEY(len) _IOC(_IOC_READ, 'E', 0x18, len) /* get global key state */
#define EVIOCGLED(len) _IOC(_IOC_READ, 'E', 0x19, len) /* get all LEDs */
#define EVIOCGSND(len) _IOC(_IOC_READ, 'E', 0x1a, len) /* get all sounds status */