[PATCH v3 08/17] HID: input: calculate resolution for pressure

From: Angela Czubak <acz@semihalf.com>
To: linux-input@vger.kernel.org
Cc: upstream@semihalf.com, benjamin.tissoires@redhat.com,
	jikos@kernel.org, dmitry.torokhov@gmail.com,
	Angela Czubak <acz@semihalf.com>
Subject: [PATCH v3 08/17] HID: input: calculate resolution for pressure
Date: Fri, 13 May 2022 09:39:18 +0000	[thread overview]
Message-ID: <20220513093927.1632262-9-acz@semihalf.com> (raw)
In-Reply-To: <20220513093927.1632262-1-acz@semihalf.com>

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 <acz@semihalf.com>
---
 drivers/hid/hid-input.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 77f2930f78f5..c9f8405c0522 100644
--- 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;
 	}
-- 
2.36.0.550.gb090851708-goog

