HID: wacom: generic: Send BTN_STYLUS3 when both barrel switches are set

The Wacom Pro Pen 3D includes a third barrel switch which is intended to
be particularly useful in applications where one frequency uses pan, zoom,
and rotate to navigate around a scene or model. The pen is compatible with
the MobileStudio Pro, 2nd-gen Intuos Pro, and Cintiq Pro. When the third
button is pressed, these devices set both the HID_DG_BARRELSWITCH and
HID_DG_BARRELSWITCH2 usages since their HID descriptors do not include a
usage specific to the button.

Rather than send both BTN_STYLUS and BTN_STYLUS2 when the third button is
pressed, userspace (libinput) has requested that we detect this condition
and report a newly-defined BTN_STYLUS3 event instead. We could define a
quirk specific to devices compatible with the Pro Pen 3D, but the liklihood
of seeing both barrel switch bits set with other pens/devices is low enough
to not worry about (pens mechanically prevent accidental activation of
multiple switches).

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Peter Hutterer <peter.hutterer@who-t.net>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

3 files changed, 19 insertions, 2 deletions

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index e3223b0c4f90..16af6886e828 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -2140,6 +2140,12 @@ static void wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field
         case HID_DG_TIPSWITCH:
                 wacom_wac->hid_data.tipswitch |= value;
                 return;
+        case HID_DG_BARRELSWITCH:
+                wacom_wac->hid_data.barrelswitch = value;
+                return;
+        case HID_DG_BARRELSWITCH2:
+                wacom_wac->hid_data.barrelswitch2 = value;
+                return;
         case HID_DG_TOOLSERIALNUMBER:
                 if (value) {
                         wacom_wac->serial[0] = (wacom_wac->serial[0] & ~0xFFFFFFFFULL);
@@ -2254,6 +2260,12 @@ static void wacom_wac_pen_report(struct hid_device *hdev,
 
         if (!delay_pen_events(wacom_wac) && wacom_wac->tool[0]) {
                 int id = wacom_wac->id[0];
+                int sw_state = wacom_wac->hid_data.barrelswitch |
+                               (wacom_wac->hid_data.barrelswitch2 << 1);
+
+                input_report_key(input, BTN_STYLUS, sw_state == 1);
+                input_report_key(input, BTN_STYLUS2, sw_state == 2);
+                input_report_key(input, BTN_STYLUS3, sw_state == 3);
 
                 /*
                  * Non-USI EMR tools should have their IDs mangled to
@@ -3300,9 +3312,11 @@ int wacom_setup_pen_input_capabilities(struct input_dev *input_dev,
         else
                 __set_bit(INPUT_PROP_POINTER, input_dev->propbit);
 
-        if (features->type == HID_GENERIC)
-                /* setup has already been done */
+        if (features->type == HID_GENERIC) {
+                /* setup has already been done; apply otherwise-undetectible quirks */
+                input_set_capability(input_dev, EV_KEY, BTN_STYLUS3);
                 return 0;
+        }
 
         __set_bit(BTN_TOUCH, input_dev->keybit);
         __set_bit(ABS_MISC, input_dev->absbit);
diff --git a/drivers/hid/wacom_wac.h b/drivers/hid/wacom_wac.h
index 8a03654048bf..69dda27e8dde 100644
--- a/drivers/hid/wacom_wac.h
+++ b/drivers/hid/wacom_wac.h
@@ -291,6 +291,8 @@ struct hid_data {
         bool inrange_state;
         bool invert_state;
         bool tipswitch;
+        bool barrelswitch;
+        bool barrelswitch2;
         int x;
         int y;
         int pressure;
diff --git a/include/uapi/linux/input-event-codes.h b/include/uapi/linux/input-event-codes.h
index 179891074b3c..9b3a522f50d1 100644
--- a/include/uapi/linux/input-event-codes.h
+++ b/include/uapi/linux/input-event-codes.h
@@ -406,6 +406,7 @@
 #define BTN_TOOL_MOUSE          0x146
 #define BTN_TOOL_LENS           0x147
 #define BTN_TOOL_QUINTTAP       0x148   /* Five fingers on trackpad */
+#define BTN_STYLUS3             0x149
 #define BTN_TOUCH               0x14a
 #define BTN_STYLUS              0x14b
 #define BTN_STYLUS2             0x14c