HID: multitouch: implement precision touchpad latency and switches

The Win 8.1 precision touchpad spec introduce new modes for touchpads
that can come in handy[1].

Implement the settings of these modes, so we are not taken off-guard if
a firmware decides to enforce them.

[1] https://docs.microsoft.com/en-us/windows-hardware/design/component-guidelines/windows-precision-touchpad-required-hid-top-level-collections

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

2 files changed, 32 insertions, 5 deletions

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 8878de9eedba..82c98bf14d60 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -81,6 +81,11 @@ MODULE_LICENSE("GPL");
 
 #define MT_BUTTONTYPE_CLICKPAD          0
 
+enum latency_mode {
+        HID_LATENCY_NORMAL = 0,
+        HID_LATENCY_HIGH = 1,
+};
+
 #define MT_IO_FLAGS_RUNNING             0
 #define MT_IO_FLAGS_ACTIVE_SLOTS        1
 #define MT_IO_FLAGS_PENDING_SLOTS       2
@@ -1156,7 +1161,10 @@ static void mt_report(struct hid_device *hid, struct hid_report *report)
 
 static bool mt_need_to_apply_feature(struct hid_device *hdev,
                                      struct hid_field *field,
-                                     struct hid_usage *usage)
+                                     struct hid_usage *usage,
+                                     enum latency_mode latency,
+                                     bool surface_switch,
+                                     bool button_switch)
 {
         struct mt_device *td = hid_get_drvdata(hdev);
         struct mt_class *cls = &td->mtclass;
@@ -1195,12 +1203,25 @@ static bool mt_need_to_apply_feature(struct hid_device *hdev,
                         }
                 }
                 break;
+
+        case HID_DG_LATENCYMODE:
+                field->value[index] = latency;
+                return 1;
+
+        case HID_DG_SURFACESWITCH:
+                field->value[index] = surface_switch;
+                return 1;
+
+        case HID_DG_BUTTONSWITCH:
+                field->value[index] = button_switch;
+                return 1;
         }
 
         return false; /* no need to update the report */
 }
 
-static void mt_set_modes(struct hid_device *hdev)
+static void mt_set_modes(struct hid_device *hdev, enum latency_mode latency,
+                         bool surface_switch, bool button_switch)
 {
         struct hid_report_enum *rep_enum;
         struct hid_report *rep;
@@ -1222,7 +1243,10 @@ static void mt_set_modes(struct hid_device *hdev)
 
                                 if (mt_need_to_apply_feature(hdev,
                                                              rep->field[i],
-                                                             usage))
+                                                             usage,
+                                                             latency,
+                                                             surface_switch,
+                                                             button_switch))
                                         update_report = true;
                         }
                 }
@@ -1467,7 +1491,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
                 dev_warn(&hdev->dev, "Cannot allocate sysfs group for %s\n",
                                 hdev->name);
 
-        mt_set_modes(hdev);
+        mt_set_modes(hdev, HID_LATENCY_NORMAL, true, true);
 
         /* release .fields memory as it is not used anymore */
         devm_kfree(&hdev->dev, td->fields);
@@ -1480,7 +1504,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
 static int mt_reset_resume(struct hid_device *hdev)
 {
         mt_release_contacts(hdev);
-        mt_set_modes(hdev);
+        mt_set_modes(hdev, HID_LATENCY_NORMAL, true, true);
         return 0;
 }
 
diff --git a/include/linux/hid.h b/include/linux/hid.h
index f03d7a410c5d..a1be991e1eae 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -292,9 +292,12 @@ struct hid_item {
 #define HID_DG_CONTACTCOUNT     0x000d0054
 #define HID_DG_CONTACTMAX       0x000d0055
 #define HID_DG_SCANTIME         0x000d0056
+#define HID_DG_SURFACESWITCH    0x000d0057
+#define HID_DG_BUTTONSWITCH     0x000d0058
 #define HID_DG_BUTTONTYPE       0x000d0059
 #define HID_DG_BARRELSWITCH2    0x000d005a
 #define HID_DG_TOOLSERIALNUMBER 0x000d005b
+#define HID_DG_LATENCYMODE      0x000d0060
 
 #define HID_VD_ASUS_CUSTOM_MEDIA_KEYS   0xff310076
 /*