HID: wacom: Discover device_type from HID descriptor for all devices

Currently, we assume a device_type of BTN_TOOL_PEN before scanning the
HID descriptor and then change the device_type if what we discover
proves that assumption wrong. This way of doing things makes it more
difficult to figure out if a device (particularly a HID_GENERIC device)
actually does tablet/touch input or is something completley different.

This patch leaves device_type at its initial value of 0 and then calls
'wacom_parse_hid' for every device (not just those that have touch).
As we map the usages, we can set the device_type as before. After we're
finished, we can then check if the value is still zero and do whatever
is most appropriate.

Detecting the pen can be a little tricky on most Wacom devices because
the descriptors describe opaque blobs. Fortunately, older Wacom tablets
have the HID_DG_DIGITIZER usage on the pen's application collection and
newer tablets seem to have a similar vendor-defined usage that we can
trigger on.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Ping Cheng <pingc@wacom.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

3 files changed, 23 insertions, 14 deletions

diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
index 222baf500435..157aa7aa1067 100644
--- a/drivers/hid/wacom_sys.c
+++ b/drivers/hid/wacom_sys.c
@@ -181,7 +181,11 @@ static void wacom_usage_mapping(struct hid_device *hdev,
         * X/Y values and some cases of invalid Digitizer X/Y
         * values commonly reported.
         */
-        if (!pen && !finger)
+        if (pen)
+                features->device_type = BTN_TOOL_PEN;
+        else if (finger)
+                features->device_type = BTN_TOOL_FINGER;
+        else
                 return;
 
         /*
@@ -198,14 +202,11 @@ static void wacom_usage_mapping(struct hid_device *hdev,
         case HID_GD_X:
                 features->x_max = field->logical_maximum;
                 if (finger) {
-                        features->device_type = BTN_TOOL_FINGER;
                         features->x_phy = field->physical_maximum;
                         if (features->type != BAMBOO_PT) {
                                 features->unit = field->unit;
                                 features->unitExpo = field->unit_exponent;
                         }
-                } else {
-                        features->device_type = BTN_TOOL_PEN;
                 }
                 break;
         case HID_GD_Y:
@@ -425,7 +426,6 @@ static void wacom_retrieve_hid_descriptor(struct hid_device *hdev,
         struct usb_interface *intf = wacom->intf;
 
         /* default features */
-        features->device_type = BTN_TOOL_PEN;
         features->x_fuzz = 4;
         features->y_fuzz = 4;
         features->pressure_fuzz = 0;
@@ -446,10 +446,6 @@ static void wacom_retrieve_hid_descriptor(struct hid_device *hdev,
                 }
         }
 
-        /* only devices that support touch need to retrieve the info */
-        if (features->type < BAMBOO_PT)
-                return;
-
         wacom_parse_hid(hdev, features);
 }
 
@@ -1529,8 +1525,15 @@ static int wacom_probe(struct hid_device *hdev,
 
         /* Retrieve the physical and logical size for touch devices */
         wacom_retrieve_hid_descriptor(hdev, features);
-
         wacom_setup_device_quirks(wacom);
+
+        if (!features->device_type && features->type != WIRELESS) {
+                dev_warn(&hdev->dev, "Unknown device_type for '%s'. %s.",
+                         hdev->name, "Assuming pen");
+
+                features->device_type = BTN_TOOL_PEN;
+        }
+
         wacom_calculate_res(features);
 
         wacom_update_name(wacom);
diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index dff99ffc1bb1..a52fc2580b6b 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -2186,13 +2186,15 @@ void wacom_setup_device_quirks(struct wacom *wacom)
 
                         features->x_max = 4096;
                         features->y_max = 4096;
-                } else {
-                        features->device_type = BTN_TOOL_PEN;
                 }
         }
 
         /*
-         * Same thing for Bamboo PAD
+         * Raw Wacom-mode pen and touch events both come from interface
+         * 0, whose HID descriptor has an application usage of 0xFF0D
+         * (i.e., WACOM_VENDORDEFINED_PEN). We route pen packets back
+         * out through the HID_GENERIC device created for interface 1,
+         * so rewrite this one to be of type BTN_TOOL_FINGER.
          */
         if (features->type == BAMBOO_PAD)
                 features->device_type = BTN_TOOL_FINGER;
diff --git a/drivers/hid/wacom_wac.h b/drivers/hid/wacom_wac.h
index f5a5f686bc98..9a5ee623cb44 100644
--- a/drivers/hid/wacom_wac.h
+++ b/drivers/hid/wacom_wac.h
@@ -72,10 +72,14 @@
 #define WACOM_QUIRK_MONITOR             0x0004
 #define WACOM_QUIRK_BATTERY             0x0008
 
+#define WACOM_VENDORDEFINED_PEN         0xff0d0001
+
 #define WACOM_PEN_FIELD(f)      (((f)->logical == HID_DG_STYLUS) || \
                                  ((f)->physical == HID_DG_STYLUS) || \
                                  ((f)->physical == HID_DG_PEN) || \
-                                 ((f)->application == HID_DG_PEN))
+                                 ((f)->application == HID_DG_PEN) || \
+                                 ((f)->application == HID_DG_DIGITIZER) || \
+                                 ((f)->application == WACOM_VENDORDEFINED_PEN))
 #define WACOM_FINGER_FIELD(f)   (((f)->logical == HID_DG_FINGER) || \
                                  ((f)->physical == HID_DG_FINGER) || \
                                  ((f)->application == HID_DG_TOUCHSCREEN))