5 files changed, 383 insertions, 28 deletions

diff --git a/Documentation/input/event-codes.rst b/Documentation/input/event-codes.rst
index a8c0873beb95..cef220c176a4 100644
--- a/Documentation/input/event-codes.rst
+++ b/Documentation/input/event-codes.rst
@@ -190,7 +190,16 @@ A few EV_REL codes have special meanings:
 * REL_WHEEL, REL_HWHEEL:
 
   - These codes are used for vertical and horizontal scroll wheels,
-    respectively.
+    respectively. The value is the number of "notches" moved on the wheel, the
+    physical size of which varies by device. For high-resolution wheels (which
+    report multiple events for each notch of movement, or do not have notches)
+    this may be an approximation based on the high-resolution scroll events.
+
+* REL_WHEEL_HI_RES:
+
+  - If a vertical scroll wheel supports high-resolution scrolling, this code
+    will be emitted in addition to REL_WHEEL. The value is the (approximate)
+    distance travelled by the user's finger, in microns.
 
 EV_ABS
 ------
diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index ad823a01bd65..567c3bf64515 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -1838,3 +1838,48 @@ void hidinput_disconnect(struct hid_device *hid)
 }
 EXPORT_SYMBOL_GPL(hidinput_disconnect);
 
+/**
+ * hid_scroll_counter_handle_scroll() - Send high- and low-resolution scroll
+ *                                      events given a high-resolution wheel
+ *                                      movement.
+ * @counter: a hid_scroll_counter struct describing the wheel.
+ * @hi_res_value: the movement of the wheel, in the mouse's high-resolution
+ *                units.
+ *
+ * Given a high-resolution movement, this function converts the movement into
+ * microns and emits high-resolution scroll events for the input device. It also
+ * uses the multiplier from &struct hid_scroll_counter to emit low-resolution
+ * scroll events when appropriate for backwards-compatibility with userspace
+ * input libraries.
+ */
+void hid_scroll_counter_handle_scroll(struct hid_scroll_counter *counter,
+                                      int hi_res_value)
+{
+        int low_res_scroll_amount;
+        /* Some wheels will rest 7/8ths of a notch from the previous notch
+         * after slow movement, so we want the threshold for low-res events to
+         * be in the middle of the notches (e.g. after 4/8ths) as opposed to on
+         * the notches themselves (8/8ths).
+         */
+        int threshold = counter->resolution_multiplier / 2;
+
+        input_report_rel(counter->dev, REL_WHEEL_HI_RES,
+                         hi_res_value * counter->microns_per_hi_res_unit);
+
+        counter->remainder += hi_res_value;
+        if (abs(counter->remainder) >= threshold) {
+                /* Add (or subtract) 1 because we want to trigger when the wheel
+                 * is half-way to the next notch (i.e. scroll 1 notch after a
+                 * 1/2 notch movement, 2 notches after a 1 1/2 notch movement,
+                 * etc.).
+                 */
+                low_res_scroll_amount =
+                        counter->remainder / counter->resolution_multiplier
+                        + (hi_res_value > 0 ? 1 : -1);
+                input_report_rel(counter->dev, REL_WHEEL,
+                                 low_res_scroll_amount);
+                counter->remainder -=
+                        low_res_scroll_amount * counter->resolution_multiplier;
+        }
+}
+EXPORT_SYMBOL_GPL(hid_scroll_counter_handle_scroll);
diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 19cc980eebce..f01280898b24 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -64,6 +64,14 @@ MODULE_PARM_DESC(disable_tap_to_click,
 #define HIDPP_QUIRK_NO_HIDINPUT                 BIT(23)
 #define HIDPP_QUIRK_FORCE_OUTPUT_REPORTS        BIT(24)
 #define HIDPP_QUIRK_UNIFYING                    BIT(25)
+#define HIDPP_QUIRK_HI_RES_SCROLL_1P0           BIT(26)
+#define HIDPP_QUIRK_HI_RES_SCROLL_X2120         BIT(27)
+#define HIDPP_QUIRK_HI_RES_SCROLL_X2121         BIT(28)
+
+/* Convenience constant to check for any high-res support. */
+#define HIDPP_QUIRK_HI_RES_SCROLL       (HIDPP_QUIRK_HI_RES_SCROLL_1P0 | \
+                                         HIDPP_QUIRK_HI_RES_SCROLL_X2120 | \
+                                         HIDPP_QUIRK_HI_RES_SCROLL_X2121)
 
 #define HIDPP_QUIRK_DELAYED_INIT                HIDPP_QUIRK_NO_HIDINPUT
 
@@ -149,6 +157,7 @@ struct hidpp_device {
         unsigned long capabilities;
 
         struct hidpp_battery battery;
+        struct hid_scroll_counter vertical_wheel_counter;
 };
 
 /* HID++ 1.0 error codes */
@@ -400,32 +409,53 @@ static void hidpp_prefix_name(char **name, int name_length)
 #define HIDPP_SET_LONG_REGISTER                         0x82
 #define HIDPP_GET_LONG_REGISTER                         0x83
 
-#define HIDPP_REG_GENERAL                               0x00
-
-static int hidpp10_enable_battery_reporting(struct hidpp_device *hidpp_dev)
+/**
+ * hidpp10_set_register_bit() - Sets a single bit in a HID++ 1.0 register.
+ * @hidpp_dev: the device to set the register on.
+ * @register_address: the address of the register to modify.
+ * @byte: the byte of the register to modify. Should be less than 3.
+ * Return: 0 if successful, otherwise a negative error code.
+ */
+static int hidpp10_set_register_bit(struct hidpp_device *hidpp_dev,
+        u8 register_address, u8 byte, u8 bit)
 {
         struct hidpp_report response;
         int ret;
         u8 params[3] = { 0 };
 
         ret = hidpp_send_rap_command_sync(hidpp_dev,
-                                        REPORT_ID_HIDPP_SHORT,
-                                        HIDPP_GET_REGISTER,
-                                        HIDPP_REG_GENERAL,
-                                        NULL, 0, &response);
+                                          REPORT_ID_HIDPP_SHORT,
+                                          HIDPP_GET_REGISTER,
+                                          register_address,
+                                          NULL, 0, &response);
         if (ret)
                 return ret;
 
         memcpy(params, response.rap.params, 3);
 
-        /* Set the battery bit */
-        params[0] |= BIT(4);
+        params[byte] |= BIT(bit);
 
         return hidpp_send_rap_command_sync(hidpp_dev,
-                                        REPORT_ID_HIDPP_SHORT,
-                                        HIDPP_SET_REGISTER,
-                                        HIDPP_REG_GENERAL,
-                                        params, 3, &response);
+                                           REPORT_ID_HIDPP_SHORT,
+                                           HIDPP_SET_REGISTER,
+                                           register_address,
+                                           params, 3, &response);
+}
+
+
+#define HIDPP_REG_GENERAL                               0x00
+
+static int hidpp10_enable_battery_reporting(struct hidpp_device *hidpp_dev)
+{
+        return hidpp10_set_register_bit(hidpp_dev, HIDPP_REG_GENERAL, 0, 4);
+}
+
+#define HIDPP_REG_FEATURES                              0x01
+
+/* On HID++ 1.0 devices, high-res scroll was called "scrolling acceleration". */
+static int hidpp10_enable_scrolling_acceleration(struct hidpp_device *hidpp_dev)
+{
+        return hidpp10_set_register_bit(hidpp_dev, HIDPP_REG_FEATURES, 0, 6);
 }
 
 #define HIDPP_REG_BATTERY_STATUS                        0x07
@@ -1137,6 +1167,100 @@ static int hidpp_battery_get_property(struct power_supply *psy,
 }
 
 /* -------------------------------------------------------------------------- */
+/* 0x2120: Hi-resolution scrolling                                            */
+/* -------------------------------------------------------------------------- */
+
+#define HIDPP_PAGE_HI_RESOLUTION_SCROLLING                      0x2120
+
+#define CMD_HI_RESOLUTION_SCROLLING_SET_HIGHRES_SCROLLING_MODE  0x10
+
+static int hidpp_hrs_set_highres_scrolling_mode(struct hidpp_device *hidpp,
+        bool enabled, u8 *multiplier)
+{
+        u8 feature_index;
+        u8 feature_type;
+        int ret;
+        u8 params[1];
+        struct hidpp_report response;
+
+        ret = hidpp_root_get_feature(hidpp,
+                                     HIDPP_PAGE_HI_RESOLUTION_SCROLLING,
+                                     &feature_index,
+                                     &feature_type);
+        if (ret)
+                return ret;
+
+        params[0] = enabled ? BIT(0) : 0;
+        ret = hidpp_send_fap_command_sync(hidpp, feature_index,
+                                          CMD_HI_RESOLUTION_SCROLLING_SET_HIGHRES_SCROLLING_MODE,
+                                          params, sizeof(params), &response);
+        if (ret)
+                return ret;
+        *multiplier = response.fap.params[1];
+        return 0;
+}
+
+/* -------------------------------------------------------------------------- */
+/* 0x2121: HiRes Wheel                                                        */
+/* -------------------------------------------------------------------------- */
+
+#define HIDPP_PAGE_HIRES_WHEEL          0x2121
+
+#define CMD_HIRES_WHEEL_GET_WHEEL_CAPABILITY    0x00
+#define CMD_HIRES_WHEEL_SET_WHEEL_MODE          0x20
+
+static int hidpp_hrw_get_wheel_capability(struct hidpp_device *hidpp,
+        u8 *multiplier)
+{
+        u8 feature_index;
+        u8 feature_type;
+        int ret;
+        struct hidpp_report response;
+
+        ret = hidpp_root_get_feature(hidpp, HIDPP_PAGE_HIRES_WHEEL,
+                                     &feature_index, &feature_type);
+        if (ret)
+                goto return_default;
+
+        ret = hidpp_send_fap_command_sync(hidpp, feature_index,
+                                          CMD_HIRES_WHEEL_GET_WHEEL_CAPABILITY,
+                                          NULL, 0, &response);
+        if (ret)
+                goto return_default;
+
+        *multiplier = response.fap.params[0];
+        return 0;
+return_default:
+        hid_warn(hidpp->hid_dev,
+                 "Couldn't get wheel multiplier (error %d), assuming %d.\n",
+                 ret, *multiplier);
+        return ret;
+}
+
+static int hidpp_hrw_set_wheel_mode(struct hidpp_device *hidpp, bool invert,
+        bool high_resolution, bool use_hidpp)
+{
+        u8 feature_index;
+        u8 feature_type;
+        int ret;
+        u8 params[1];
+        struct hidpp_report response;
+
+        ret = hidpp_root_get_feature(hidpp, HIDPP_PAGE_HIRES_WHEEL,
+                                     &feature_index, &feature_type);
+        if (ret)
+                return ret;
+
+        params[0] = (invert          ? BIT(2) : 0) |
+                    (high_resolution ? BIT(1) : 0) |
+                    (use_hidpp       ? BIT(0) : 0);
+
+        return hidpp_send_fap_command_sync(hidpp, feature_index,
+                                           CMD_HIRES_WHEEL_SET_WHEEL_MODE,
+                                           params, sizeof(params), &response);
+}
+
+/* -------------------------------------------------------------------------- */
 /* 0x4301: Solar Keyboard                                                     */
 /* -------------------------------------------------------------------------- */
 
@@ -2399,7 +2523,8 @@ static int m560_raw_event(struct hid_device *hdev, u8 *data, int size)
                 input_report_rel(mydata->input, REL_Y, v);
 
                 v = hid_snto32(data[6], 8);
-                input_report_rel(mydata->input, REL_WHEEL, v);
+                hid_scroll_counter_handle_scroll(
+                                &hidpp->vertical_wheel_counter, v);
 
                 input_sync(mydata->input);
         }
@@ -2528,6 +2653,72 @@ static int g920_get_config(struct hidpp_device *hidpp)
 }
 
 /* -------------------------------------------------------------------------- */
+/* High-resolution scroll wheels                                              */
+/* -------------------------------------------------------------------------- */
+
+/**
+ * struct hi_res_scroll_info - Stores info on a device's high-res scroll wheel.
+ * @product_id: the HID product ID of the device being described.
+ * @microns_per_hi_res_unit: the distance moved by the user's finger for each
+ *                         high-resolution unit reported by the device, in
+ *                         256ths of a millimetre.
+ */
+struct hi_res_scroll_info {
+        __u32 product_id;
+        int microns_per_hi_res_unit;
+};
+
+static struct hi_res_scroll_info hi_res_scroll_devices[] = {
+        { /* Anywhere MX */
+          .product_id = 0x1017, .microns_per_hi_res_unit = 445 },
+        { /* Performance MX */
+          .product_id = 0x101a, .microns_per_hi_res_unit = 406 },
+        { /* M560 */
+          .product_id = 0x402d, .microns_per_hi_res_unit = 435 },
+        { /* MX Master 2S */
+          .product_id = 0x4069, .microns_per_hi_res_unit = 406 },
+};
+
+static int hi_res_scroll_look_up_microns(__u32 product_id)
+{
+        int i;
+        int num_devices = sizeof(hi_res_scroll_devices)
+                          / sizeof(hi_res_scroll_devices[0]);
+        for (i = 0; i < num_devices; i++) {
+                if (hi_res_scroll_devices[i].product_id == product_id)
+                        return hi_res_scroll_devices[i].microns_per_hi_res_unit;
+        }
+        /* We don't have a value for this device, so use a sensible default. */
+        return 406;
+}
+
+static int hi_res_scroll_enable(struct hidpp_device *hidpp)
+{
+        int ret;
+        u8 multiplier = 8;
+
+        if (hidpp->quirks & HIDPP_QUIRK_HI_RES_SCROLL_X2121) {
+                ret = hidpp_hrw_set_wheel_mode(hidpp, false, true, false);
+                hidpp_hrw_get_wheel_capability(hidpp, &multiplier);
+        } else if (hidpp->quirks & HIDPP_QUIRK_HI_RES_SCROLL_X2120) {
+                ret = hidpp_hrs_set_highres_scrolling_mode(hidpp, true,
+                                                           &multiplier);
+        } else /* if (hidpp->quirks & HIDPP_QUIRK_HI_RES_SCROLL_1P0) */
+                ret = hidpp10_enable_scrolling_acceleration(hidpp);
+
+        if (ret)
+                return ret;
+
+        hidpp->vertical_wheel_counter.resolution_multiplier = multiplier;
+        hidpp->vertical_wheel_counter.microns_per_hi_res_unit =
+                hi_res_scroll_look_up_microns(hidpp->hid_dev->product);
+        hid_info(hidpp->hid_dev, "multiplier = %d, microns = %d\n",
+                 multiplier,
+                 hidpp->vertical_wheel_counter.microns_per_hi_res_unit);
+        return 0;
+}
+
+/* -------------------------------------------------------------------------- */
 /* Generic HID++ devices                                                      */
 /* -------------------------------------------------------------------------- */
 
@@ -2572,6 +2763,11 @@ static void hidpp_populate_input(struct hidpp_device *hidpp,
                 wtp_populate_input(hidpp, input, origin_is_hid_core);
         else if (hidpp->quirks & HIDPP_QUIRK_CLASS_M560)
                 m560_populate_input(hidpp, input, origin_is_hid_core);
+
+        if (hidpp->quirks & HIDPP_QUIRK_HI_RES_SCROLL) {
+                input_set_capability(input, EV_REL, REL_WHEEL_HI_RES);
+                hidpp->vertical_wheel_counter.dev = input;
+        }
 }
 
 static int hidpp_input_configured(struct hid_device *hdev,
@@ -2690,6 +2886,27 @@ static int hidpp_raw_event(struct hid_device *hdev, struct hid_report *report,
         return 0;
 }
 
+static int hidpp_event(struct hid_device *hdev, struct hid_field *field,
+        struct hid_usage *usage, __s32 value)
+{
+        /* This function will only be called for scroll events, due to the
+         * restriction imposed in hidpp_usages.
+         */
+        struct hidpp_device *hidpp = hid_get_drvdata(hdev);
+        struct hid_scroll_counter *counter = &hidpp->vertical_wheel_counter;
+        /* A scroll event may occur before the multiplier has been retrieved or
+         * the input device set, or high-res scroll enabling may fail. In such
+         * cases we must return early (falling back to default behaviour) to
+         * avoid a crash in hid_scroll_counter_handle_scroll.
+         */
+        if (!(hidpp->quirks & HIDPP_QUIRK_HI_RES_SCROLL) || value == 0
+            || counter->dev == NULL || counter->resolution_multiplier == 0)
+                return 0;
+
+        hid_scroll_counter_handle_scroll(counter, value);
+        return 1;
+}
+
 static int hidpp_initialize_battery(struct hidpp_device *hidpp)
 {
         static atomic_t battery_no = ATOMIC_INIT(0);
@@ -2901,6 +3118,9 @@ static void hidpp_connect_event(struct hidpp_device *hidpp)
         if (hidpp->battery.ps)
                 power_supply_changed(hidpp->battery.ps);
 
+        if (hidpp->quirks & HIDPP_QUIRK_HI_RES_SCROLL)
+                hi_res_scroll_enable(hidpp);
+
         if (!(hidpp->quirks & HIDPP_QUIRK_NO_HIDINPUT) || hidpp->delayed_input)
                 /* if the input nodes are already created, we can stop now */
                 return;
@@ -3086,35 +3306,63 @@ static void hidpp_remove(struct hid_device *hdev)
         mutex_destroy(&hidpp->send_mutex);
 }
 
+#define LDJ_DEVICE(product) \
+        HID_DEVICE(BUS_USB, HID_GROUP_LOGITECH_DJ_DEVICE, \
+                   USB_VENDOR_ID_LOGITECH, (product))
+
 static const struct hid_device_id hidpp_devices[] = {
         { /* wireless touchpad */
-          HID_DEVICE(BUS_USB, HID_GROUP_LOGITECH_DJ_DEVICE,
-                USB_VENDOR_ID_LOGITECH, 0x4011),
+          LDJ_DEVICE(0x4011),
           .driver_data = HIDPP_QUIRK_CLASS_WTP | HIDPP_QUIRK_DELAYED_INIT |
                          HIDPP_QUIRK_WTP_PHYSICAL_BUTTONS },
         { /* wireless touchpad T650 */
-          HID_DEVICE(BUS_USB, HID_GROUP_LOGITECH_DJ_DEVICE,
-                USB_VENDOR_ID_LOGITECH, 0x4101),
+          LDJ_DEVICE(0x4101),
           .driver_data = HIDPP_QUIRK_CLASS_WTP | HIDPP_QUIRK_DELAYED_INIT },
         { /* wireless touchpad T651 */
           HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_LOGITECH,
                 USB_DEVICE_ID_LOGITECH_T651),
           .driver_data = HIDPP_QUIRK_CLASS_WTP },
+        { /* Mouse Logitech Anywhere MX */
+          LDJ_DEVICE(0x1017), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_1P0 },
+        { /* Mouse Logitech Cube */
+          LDJ_DEVICE(0x4010), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2120 },
+        { /* Mouse Logitech M335 */
+          LDJ_DEVICE(0x4050), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { /* Mouse Logitech M515 */
+          LDJ_DEVICE(0x4007), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2120 },
         { /* Mouse logitech M560 */
-          HID_DEVICE(BUS_USB, HID_GROUP_LOGITECH_DJ_DEVICE,
-                USB_VENDOR_ID_LOGITECH, 0x402d),
-          .driver_data = HIDPP_QUIRK_DELAYED_INIT | HIDPP_QUIRK_CLASS_M560 },
+          LDJ_DEVICE(0x402d),
+          .driver_data = HIDPP_QUIRK_DELAYED_INIT | HIDPP_QUIRK_CLASS_M560
+                | HIDPP_QUIRK_HI_RES_SCROLL_X2120 },
+        { /* Mouse Logitech M705 (firmware RQM17) */
+          LDJ_DEVICE(0x101b), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_1P0 },
+        { /* Mouse Logitech M705 (firmware RQM67) */
+          LDJ_DEVICE(0x406d), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { /* Mouse Logitech M720 */
+          LDJ_DEVICE(0x405e), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { /* Mouse Logitech MX Anywhere 2 */
+          LDJ_DEVICE(0x404a), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { LDJ_DEVICE(0xb013), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { LDJ_DEVICE(0xb018), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { LDJ_DEVICE(0xb01f), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { /* Mouse Logitech MX Anywhere 2S */
+          LDJ_DEVICE(0x406a), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { /* Mouse Logitech MX Master */
+          LDJ_DEVICE(0x4041), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { LDJ_DEVICE(0x4060), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { LDJ_DEVICE(0x4071), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { /* Mouse Logitech MX Master 2S */
+          LDJ_DEVICE(0x4069), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_X2121 },
+        { /* Mouse Logitech Performance MX */
+          LDJ_DEVICE(0x101a), .driver_data = HIDPP_QUIRK_HI_RES_SCROLL_1P0 },
         { /* Keyboard logitech K400 */
-          HID_DEVICE(BUS_USB, HID_GROUP_LOGITECH_DJ_DEVICE,
-                USB_VENDOR_ID_LOGITECH, 0x4024),
+          LDJ_DEVICE(0x4024),
           .driver_data = HIDPP_QUIRK_CLASS_K400 },
         { /* Solar Keyboard Logitech K750 */
-          HID_DEVICE(BUS_USB, HID_GROUP_LOGITECH_DJ_DEVICE,
-                USB_VENDOR_ID_LOGITECH, 0x4002),
+          LDJ_DEVICE(0x4002),
           .driver_data = HIDPP_QUIRK_CLASS_K750 },
 
-        { HID_DEVICE(BUS_USB, HID_GROUP_LOGITECH_DJ_DEVICE,
-                USB_VENDOR_ID_LOGITECH, HID_ANY_ID)},
+        { LDJ_DEVICE(HID_ANY_ID) },
 
         { HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH, USB_DEVICE_ID_LOGITECH_G920_WHEEL),
                 .driver_data = HIDPP_QUIRK_CLASS_G920 | HIDPP_QUIRK_FORCE_OUTPUT_REPORTS},
@@ -3123,12 +3371,19 @@ static const struct hid_device_id hidpp_devices[] = {
 
 MODULE_DEVICE_TABLE(hid, hidpp_devices);
 
+static const struct hid_usage_id hidpp_usages[] = {
+        { HID_GD_WHEEL, EV_REL, REL_WHEEL },
+        { HID_ANY_ID - 1, HID_ANY_ID - 1, HID_ANY_ID - 1}
+};
+
 static struct hid_driver hidpp_driver = {
         .name = "logitech-hidpp-device",
         .id_table = hidpp_devices,
         .probe = hidpp_probe,
         .remove = hidpp_remove,
         .raw_event = hidpp_raw_event,
+        .usage_table = hidpp_usages,
+        .event = hidpp_event,
         .input_configured = hidpp_input_configured,
         .input_mapping = hidpp_input_mapping,
         .input_mapped = hidpp_input_mapped,
diff --git a/include/linux/hid.h b/include/linux/hid.h
index d44a78362942..2827b87590d8 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -1139,6 +1139,34 @@ static inline u32 hid_report_len(struct hid_report *report)
 int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, u32 size,
                 int interrupt);
 
+
+/**
+ * struct hid_scroll_counter - Utility class for processing high-resolution
+ *                             scroll events.
+ * @dev: the input device for which events should be reported.
+ * @microns_per_hi_res_unit: the amount moved by the user's finger for each
+ *                           high-resolution unit reported by the mouse, in
+ *                           microns.
+ * @resolution_multiplier: the wheel's resolution in high-resolution mode as a
+ *                         multiple of its lower resolution. For example, if
+ *                         moving the wheel by one "notch" would result in a
+ *                         value of 1 in low-resolution mode but 8 in
+ *                         high-resolution, the multiplier is 8.
+ * @remainder: counts the number of high-resolution units moved since the last
+ *             low-resolution event (REL_WHEEL or REL_HWHEEL) was sent. Should
+ *             only be used by class methods.
+ */
+struct hid_scroll_counter {
+        struct input_dev *dev;
+        int microns_per_hi_res_unit;
+        int resolution_multiplier;
+
+        int remainder;
+};
+
+void hid_scroll_counter_handle_scroll(struct hid_scroll_counter *counter,
+                                      int hi_res_value);
+
 /* HID quirks API */
 unsigned long hid_lookup_quirk(const struct hid_device *hdev);
 int hid_quirks_init(char **quirks_param, __u16 bus, int count);
diff --git a/include/uapi/linux/input-event-codes.h b/include/uapi/linux/input-event-codes.h
index 53fbae27b280..6d180cc60a5d 100644
--- a/include/uapi/linux/input-event-codes.h
+++ b/include/uapi/linux/input-event-codes.h
@@ -708,6 +708,15 @@
 #define REL_DIAL                0x07
 #define REL_WHEEL               0x08
 #define REL_MISC                0x09
+/*
+ * 0x0a is reserved and should not be used in input drivers.
+ * It was used by HID as REL_MISC+1 and userspace needs to detect if
+ * the next REL_* event is correct or is just REL_MISC + n.
+ * We define here REL_RESERVED so userspace can rely on it and detect
+ * the situation described above.
+ */
+#define REL_RESERVED            0x0a
+#define REL_WHEEL_HI_RES        0x0b
 #define REL_MAX                 0x0f
 #define REL_CNT                 (REL_MAX+1)
 
@@ -744,6 +753,15 @@
 
 #define ABS_MISC                0x28
 
+/*
+ * 0x2e is reserved and should not be used in input drivers.
+ * It was used by HID as ABS_MISC+6 and userspace needs to detect if
+ * the next ABS_* event is correct or is just ABS_MISC + n.
+ * We define here ABS_RESERVED so userspace can rely on it and detect
+ * the situation described above.
+ */
+#define ABS_RESERVED            0x2e
+
 #define ABS_MT_SLOT             0x2f    /* MT slot being modified */
 #define ABS_MT_TOUCH_MAJOR      0x30    /* Major axis of touching ellipse */
 #define ABS_MT_TOUCH_MINOR      0x31    /* Minor axis (omit if circular) */