HID: wacom: generic: Scale battery capacity measurements to percentages

The power_supply subsystem expects us to provide it with capacity values
measured in percent. In particular, AES devices (HID_DG_BATTERYSTRENGTH)
use the range 0-255, which needs to be rescaled. The MobileStudio Pro
(WACOM_HID_WD_BATTERY_LEVEL) uses the range 0-100, but there's no guarantee
that future devices will share the same range.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Ping Cheng <ping.cheng@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 4b225fb..fd989e0 100644 (file)
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -1811,6 +1811,7 @@ static void wacom_wac_pad_battery_event(struct hid_device *hdev, struct hid_fiel
 
        switch (equivalent_usage) {
        case WACOM_HID_WD_BATTERY_LEVEL:
+               value = value * 100 / (field->logical_maximum - field->logical_minimum);
                wacom_wac->hid_data.battery_capacity = value;
                wacom_wac->hid_data.bat_connected = 1;
                break;
@@ -2035,6 +2036,7 @@ static void wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field
                        wacom_wac->hid_data.sense_state = value;
                return;
        case HID_DG_BATTERYSTRENGTH:
+               value = value * 100 / (field->logical_maximum - field->logical_minimum);
                wacom_wac->hid_data.battery_capacity = value;
                wacom_wac->hid_data.bat_connected = 1;
                break;