HID: input: calculate resolution for pressure

Assume that if the pressure is given in newtons it should be normalized
to grams. If the pressure has no unit do not calculate resolution.

Signed-off-by: Angela Czubak <aczubak@google.com>
Co-developed-by: Jonathan Denose <jdenose@google.com>
Signed-off-by: Jonathan Denose <jdenose@google.com>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index f6a920fe3102e7bf71a4f77c6b81ed133fe5b506..5d7532d79d21c1476e7ed2d332dad368cf464386 100644 (file)
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -303,6 +303,19 @@ __s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code)
                }
                break;
 
+       case ABS_PRESSURE:
+       case ABS_MT_PRESSURE:
+               if (field->unit == HID_UNIT_NEWTON) {
+                       /* Convert to grams, 1 newton is 101.97 grams */
+                       prev = physical_extents;
+                       physical_extents *= 10197;
+                       if (physical_extents < prev)
+                               return 0;
+                       unit_exponent -= 2;
+               } else if (field->unit != HID_UNIT_GRAM) {
+                       return 0;
+               }
+               break;
        default:
                return 0;
        }