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Date:   Wed, 28 Nov 2018 13:38:33 +1000
From:   Peter Hutterer <peter.hutterer@who-t.net>
To:     linux-input@vger.kernel.org
Cc:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Jiri Kosina <jikos@kernel.org>,
        Harry Cutts <hcutts@chromium.org>,
        torvalds@linux-foundation.org,
        Nestor Lopez Casado <nlopezcasad@logitech.com>,
        linux-kernel@vger.kernel.org,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>
Subject: [PATCH v2 8/8] HID: logitech: Enable high-resolution scrolling on
 Logitech mice
Message-ID: <20181128033833.GA20646@jelly>
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From: Harry Cutts <hcutts@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 <hcutts@chromium.org>
Signed-off-by: Peter Hutterer <peter.hutterer@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