From: Harry Cutts <hcu...@chromium.org>

There are three features used by various Logitech mice for
high-resolution scrolling: the scrolling acceleration bit in HID++ 1.0,
and the x2120 and x2121 features in HID++ 2.0 and above. This patch
supports all three, and uses the multiplier reported by the mouse for
the HID++ 2.0+ features.

The full list of product IDs of mice which support high-resolution
scrolling was provided by Logitech, but the patch was tested using the
following mice (using the Unifying receiver):

* HID++ 1.0: Anywhere MX, Performance MX
* x2120: M560
* x2121: MX Anywhere 2, MX Master 2S

This patch is a combinations of the now-reverted commits 1ff2e1a44e0,
d56ca9855bf9, 5fe2ccbef9d, 044ee89028 together with some extra bits for the
directional and timeout-based reset.
The previous patch series was in hid-input, it appears this remainder
handling is logitech-specific and was moved to hid-logitech-hidpp.c and
renamed accordingly.

Signed-off-by: Harry Cutts <hcu...@chromium.org>
Signed-off-by: Peter Hutterer <peter.hutte...@who-t.net>
---
Changes to v1:
- get rid of the timer in favour of sched_clock()
- drop storing the multiplier and calculate value on the fly

 drivers/hid/hid-logitech-hidpp.c | 292 ++++++++++++++++++++++++++++++-
 1 file changed, 288 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 67ca587aecfa..236ed256e4e7 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -21,6 +21,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
+#include <linux/sched/clock.h>
 #include <linux/kfifo.h>
 #include <linux/input/mt.h>
 #include <linux/workqueue.h>
@@ -64,6 +65,14 @@ 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
 
@@ -128,6 +137,25 @@ struct hidpp_battery {
        bool online;
 };
 
+/**
+ * struct hidpp_scroll_counter - Utility class for processing high-resolution
+ *                             scroll events.
+ * @dev: the input device for which events should be reported.
+ * @wheel_multiplier: the scalar multiplier to be applied to each wheel event
+ * @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.
+ * @direction: direction of last movement (1 or -1)
+ * @last_time: last event time, used to reset remainder after inactivity
+ */
+struct hidpp_scroll_counter {
+       struct input_dev *dev;
+       int wheel_multiplier;
+       int remainder;
+       int direction;
+       unsigned long long last_time;
+};
+
 struct hidpp_device {
        struct hid_device *hid_dev;
        struct mutex send_mutex;
@@ -149,6 +177,7 @@ struct hidpp_device {
        unsigned long capabilities;
 
        struct hidpp_battery battery;
+       struct hidpp_scroll_counter vertical_wheel_counter;
 };
 
 /* HID++ 1.0 error codes */
@@ -391,6 +420,67 @@ static void hidpp_prefix_name(char **name, int name_length)
        *name = new_name;
 }
 
+/**
+ * hidpp_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
+ * fractions of 120 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.
+ */
+static void hidpp_scroll_counter_handle_scroll(struct hidpp_scroll_counter 
*counter,
+                                              int hi_res_value)
+{
+       int low_res_value, remainder, direction;
+       unsigned long long now, previous;
+
+       hi_res_value = hi_res_value * 120/counter->wheel_multiplier;
+       input_report_rel(counter->dev, REL_WHEEL_HI_RES, hi_res_value);
+
+       remainder = counter->remainder;
+       direction = hi_res_value > 0 ? 1 : -1;
+
+       now = sched_clock();
+       previous = counter->last_time;
+       counter->last_time = now;
+       /*
+        * Reset the remainder after a period of inactivity or when the
+        * direction changes. This prevents the REL_WHEEL emulation point
+        * from sliding for devices that don't always provide the same
+        * number of movements per detent.
+        */
+       if (now - previous > 1000000000 || direction != counter->direction)
+               remainder = 0;
+
+       counter->direction = direction;
+       remainder += hi_res_value;
+
+       /* Some wheels will rest 7/8ths of a detent from the previous detent
+        * after slow movement, so we want the threshold for low-res events to
+        * be in the middle between two detents (e.g. after 4/8ths) as
+        * opposed to on the detents themselves (8/8ths).
+        */
+       if (abs(remainder) >= 60) {
+               /* Add (or subtract) 1 because we want to trigger when the wheel
+                * is half-way to the next detent (i.e. scroll 1 detent after a
+                * 1/2 detent movement, 2 detents after a 1 1/2 detent movement,
+                * etc.).
+                */
+               low_res_value = remainder / 120;
+               if (low_res_value == 0)
+                       low_res_value = (hi_res_value > 0 ? 1 : -1);
+               input_report_rel(counter->dev, REL_WHEEL, low_res_value);
+               remainder -= low_res_value * 120;
+       }
+       counter->remainder = remainder;
+}
+
 /* -------------------------------------------------------------------------- 
*/
 /* HIDP++ 1.0 commands                                                        
*/
 /* -------------------------------------------------------------------------- 
*/
@@ -1157,6 +1247,99 @@ static int hidpp_battery_get_property(struct 
power_supply *psy,
        return ret;
 }
 
+/* -------------------------------------------------------------------------- 
*/
+/* 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)\n", ret);
+       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                                                     
*/
 /* -------------------------------------------------------------------------- 
*/
@@ -2420,7 +2603,8 @@ 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);
+               hidpp_scroll_counter_handle_scroll(
+                               &hidpp->vertical_wheel_counter, v);
 
                input_sync(mydata->input);
        }
@@ -2548,6 +2732,37 @@ static int g920_get_config(struct hidpp_device *hidpp)
        return 0;
 }
 
+/* -------------------------------------------------------------------------- 
*/
+/* High-resolution scroll wheels                                              
*/
+/* -------------------------------------------------------------------------- 
*/
+
+static int hi_res_scroll_enable(struct hidpp_device *hidpp)
+{
+       int ret;
+       u8 multiplier = 1;
+
+       if (hidpp->quirks & HIDPP_QUIRK_HI_RES_SCROLL_X2121) {
+               ret = hidpp_hrw_set_wheel_mode(hidpp, false, true, false);
+               if (ret == 0)
+                       ret = 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);
+               multiplier = 8;
+       }
+       if (ret)
+               return ret;
+
+       if (multiplier == 0)
+               multiplier = 1;
+
+       hidpp->vertical_wheel_counter.wheel_multiplier = multiplier;
+       hid_info(hidpp->hid_dev, "multiplier = %d\n", multiplier);
+       return 0;
+}
+
 /* -------------------------------------------------------------------------- 
*/
 /* Generic HID++ devices                                                      
*/
 /* -------------------------------------------------------------------------- 
*/
@@ -2593,6 +2808,11 @@ 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,
@@ -2711,6 +2931,27 @@ 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 hidpp_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 hidpp_scroll_counter_handle_scroll.
+        */
+       if (!(hidpp->quirks & HIDPP_QUIRK_HI_RES_SCROLL) || value == 0
+           || counter->dev == NULL || counter->wheel_multiplier == 0)
+               return 0;
+
+       hidpp_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);
@@ -2922,6 +3163,9 @@ 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;
@@ -3107,6 +3351,10 @@ 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 */
          LDJ_DEVICE(0x4011),
@@ -3119,10 +3367,39 @@ static const struct hid_device_id hidpp_devices[] = {
          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 */
          LDJ_DEVICE(0x4024),
          .driver_data = HIDPP_QUIRK_CLASS_K400 },
@@ -3139,12 +3416,19 @@ 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_HI_RES },
+       { 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,
-- 
2.19.1

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