HID: multitouch: Add support for button type usage

According to [1], Windows Precision Touchpad devices must supply
a button type usage in the device capabilities feature report. A
value of 0 indicates that the device contains a depressible
button (i.e. it's a click-pad) whereas a value of 1 indicates
a non-depressible button. Add support for this usage and set
INPUT_PROP_BUTTONPAD on the touchpad input device whenever a
depressible button is present.

[1] https://msdn.microsoft.com/en-us/library/windows/hardware/dn467314(v=vs.85).aspx

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

3 files changed, 18 insertions, 0 deletions

diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c
index 8bf61d295ffd..4b2a18a8b7ec 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -165,6 +165,7 @@ static const struct hid_usage_entry hid_usage_table[] = {
     {0, 0x53, "DeviceIndex"},
     {0, 0x54, "ContactCount"},
     {0, 0x55, "ContactMaximumNumber"},
+    {0, 0x59, "ButtonType"},
     {0, 0x5A, "SecondaryBarrelSwitch"},
     {0, 0x5B, "TransducerSerialNumber"},
   { 15, 0, "PhysicalInterfaceDevice" },
diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index ef06dc30b9b1..55e89b16b3da 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -72,6 +72,8 @@ MODULE_LICENSE("GPL");
 #define MT_INPUTMODE_TOUCHSCREEN        0x02
 #define MT_INPUTMODE_TOUCHPAD           0x03
 
+#define MT_BUTTONTYPE_CLICKPAD          0
+
 struct mt_slot {
         __s32 x, y, cx, cy, p, w, h;
         __s32 contactid;        /* the device ContactID assigned to this slot */
@@ -117,6 +119,7 @@ struct mt_device {
                                 * 1 means we should use a serial protocol
                                 * > 1 means hybrid (multitouch) protocol */
         __u8 buttons_count;     /* number of physical buttons per touchpad */
+        bool is_buttonpad;      /* is this device a button pad? */
         bool serial_maybe;      /* need to check for serial protocol */
         bool curvalid;          /* is the current contact valid? */
         unsigned mt_flags;      /* flags to pass to input-mt */
@@ -335,6 +338,16 @@ static void mt_feature_mapping(struct hid_device *hdev,
                         td->maxcontacts = td->mtclass.maxcontacts;
 
                 break;
+        case HID_DG_BUTTONTYPE:
+                if (usage->usage_index >= field->report_count) {
+                        dev_err(&hdev->dev, "HID_DG_BUTTONTYPE out of range\n");
+                        break;
+                }
+
+                if (field->value[usage->usage_index] == MT_BUTTONTYPE_CLICKPAD)
+                        td->is_buttonpad = true;
+
+                break;
         }
 }
 
@@ -735,6 +748,9 @@ static void mt_touch_input_configured(struct hid_device *hdev,
 
         /* check for clickpads */
         if ((td->mt_flags & INPUT_MT_POINTER) && (td->buttons_count == 1))
+                td->is_buttonpad = true;
+
+        if (td->is_buttonpad)
                 __set_bit(INPUT_PROP_BUTTONPAD, input->propbit);
 
         input_mt_init_slots(input, td->maxcontacts, td->mt_flags);
diff --git a/include/linux/hid.h b/include/linux/hid.h
index efc7787a41a8..f455c38d7562 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -269,6 +269,7 @@ struct hid_item {
 #define HID_DG_DEVICEINDEX      0x000d0053
 #define HID_DG_CONTACTCOUNT     0x000d0054
 #define HID_DG_CONTACTMAX       0x000d0055
+#define HID_DG_BUTTONTYPE       0x000d0059
 #define HID_DG_BARRELSWITCH2    0x000d005a
 #define HID_DG_TOOLSERIALNUMBER 0x000d005b