Input: wacom - use hidinput_calc_abs_res instead of duplicating its code

This may infer a small difference with the previous implementation
due to the DIV_ROUND_CLOSEST() in the hid implementation.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Jason Gerecke <killertofu@gmail.com>
Tested-by: Jason Gerecke <killertofu@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 9 insertions, 39 deletions

diff --git a/drivers/input/tablet/wacom_sys.c b/drivers/input/tablet/wacom_sys.c
index ed27e7da5444..06e304b3bbfd 100644
--- a/drivers/input/tablet/wacom_sys.c
+++ b/drivers/input/tablet/wacom_sys.c
@@ -85,49 +85,19 @@ static void wacom_close(struct input_dev *dev)
 }
 
 /*
- * Calculate the resolution of the X or Y axis, given appropriate HID data.
- * This function is little more than hidinput_calc_abs_res stripped down.
+ * Calculate the resolution of the X or Y axis using hidinput_calc_abs_res.
  */
 static int wacom_calc_hid_res(int logical_extents, int physical_extents,
                                unsigned unit, int exponent)
 {
-        int prev;
-        int unit_exponent = exponent;
-
-        /* Check if the extents are sane */
-        if (logical_extents <= 0 || physical_extents <= 0)
-                return 0;
-
-        /* Convert physical_extents to millimeters */
-        if (unit == 0x11) {             /* If centimeters */
-                unit_exponent += 1;
-        } else if (unit == 0x13) {      /* If inches */
-                prev = physical_extents;
-                physical_extents *= 254;
-                if (physical_extents < prev)
-                        return 0;
-                unit_exponent -= 1;
-        } else {
-                return 0;
-        }
-
-        /* Apply negative unit exponent */
-        for (; unit_exponent < 0; unit_exponent++) {
-                prev = logical_extents;
-                logical_extents *= 10;
-                if (logical_extents < prev)
-                        return 0;
-        }
-        /* Apply positive unit exponent */
-        for (; unit_exponent > 0; unit_exponent--) {
-                prev = physical_extents;
-                physical_extents *= 10;
-                if (physical_extents < prev)
-                        return 0;
-        }
-
-        /* Calculate resolution */
-        return logical_extents / physical_extents;
+        struct hid_field field = {
+                .logical_maximum = logical_extents,
+                .physical_maximum = physical_extents,
+                .unit = unit,
+                .unit_exponent = exponent,
+        };
+
+        return hidinput_calc_abs_res(&field, ABS_X);
 }
 
 static void wacom_feature_mapping(struct hid_device *hdev,