HID: Add driver for USB ELAN Touchpad

This is driver for usb touchpad found on HP Pavilion x2 10-p0xx laptop. On this
device keyboard and touchpad connected as a single usb device with two
interfaces: keyboard, which exposes ordinary keys and second interface is
touchpad which also contains FlightMode button and audio mute led (which
physically placed on keyboard for some reason).

Initially, this touchpad works in mouse emulation mode, this driver will switch
it to touchpad mode, which can track 5 fingers and can report coordinates for
two of them.

Signed-off-by: Alexandrov Stansilav <neko@nya.ai>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 421 insertions, 0 deletions

diff --git a/drivers/hid/hid-elan.c b/drivers/hid/hid-elan.c
new file mode 100644
index 000000000000..803a725785cf
--- /dev/null
+++ b/drivers/hid/hid-elan.c
@@ -0,0 +1,421 @@
+/*
+ * HID Driver for ELAN Touchpad
+ *
+ * Currently only supports touchpad found on HP Pavilion X2 10
+ *
+ * Copyright (c) 2016 Alexandrov Stanislav <neko@nya.ai>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#include <linux/hid.h>
+#include <linux/input/mt.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+
+#include "hid-ids.h"
+
+#define ELAN_SINGLE_FINGER	0x81
+#define ELAN_MT_FIRST_FINGER	0x82
+#define ELAN_MT_SECOND_FINGER	0x83
+#define ELAN_INPUT_REPORT_SIZE	8
+
+#define ELAN_MUTE_LED_REPORT	0xBC
+#define ELAN_LED_REPORT_SIZE	8
+
+struct elan_touchpad_settings {
+	u8 max_fingers;
+	u16 max_x;
+	u16 max_y;
+	u8 max_area_x;
+	u8 max_area_y;
+	u8 max_w;
+	int usb_bInterfaceNumber;
+};
+
+struct elan_drvdata {
+	struct input_dev *input;
+	u8 prev_report[ELAN_INPUT_REPORT_SIZE];
+	struct led_classdev mute_led;
+	u8 mute_led_state;
+	struct elan_touchpad_settings *settings;
+};
+
+static int is_not_elan_touchpad(struct hid_device *hdev)
+{
+	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+	struct elan_drvdata *drvdata = hid_get_drvdata(hdev);
+
+	return (intf->altsetting->desc.bInterfaceNumber != drvdata->settings->usb_bInterfaceNumber);
+}
+
+static int elan_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+			      struct hid_field *field, struct hid_usage *usage,
+			      unsigned long **bit, int *max)
+{
+	if (is_not_elan_touchpad(hdev))
+		return 0;
+
+	if (field->report->id == ELAN_SINGLE_FINGER ||
+	    field->report->id == ELAN_MT_FIRST_FINGER ||
+	    field->report->id == ELAN_MT_SECOND_FINGER)
+		return -1;
+
+	return 0;
+}
+
+static int elan_input_configured(struct hid_device *hdev, struct hid_input *hi)
+{
+	int ret;
+	struct input_dev *input;
+	struct elan_drvdata *drvdata = hid_get_drvdata(hdev);
+
+	if (is_not_elan_touchpad(hdev))
+		return 0;
+
+	input = devm_input_allocate_device(&hdev->dev);
+	if (!input)
+		return -ENOMEM;
+
+	input->name = "Elan Touchpad";
+	input->phys = hdev->phys;
+	input->uniq = hdev->uniq;
+	input->id.bustype = hdev->bus;
+	input->id.vendor  = hdev->vendor;
+	input->id.product = hdev->product;
+	input->id.version = hdev->version;
+	input->dev.parent = &hdev->dev;
+
+	input_set_abs_params(input, ABS_MT_POSITION_X, 0,
+			     drvdata->settings->max_x, 0, 0);
+	input_set_abs_params(input, ABS_MT_POSITION_Y, 0,
+			     drvdata->settings->max_y, 0, 0);
+	input_set_abs_params(input, ABS_MT_TOUCH_MAJOR, 0,
+			     drvdata->settings->max_fingers, 0, 0);
+	input_set_abs_params(input, ABS_TOOL_WIDTH, 0,
+			     drvdata->settings->max_w, 0, 0);
+
+	__set_bit(BTN_LEFT, input->keybit);
+	__set_bit(INPUT_PROP_BUTTONPAD, input->propbit);
+
+	ret = input_mt_init_slots(input, drvdata->settings->max_fingers,
+				  INPUT_MT_POINTER);
+	if (ret) {
+		hid_err(hdev, "Failed to init elan MT slots: %d\n", ret);
+		return ret;
+	}
+
+	ret = input_register_device(input);
+	if (ret) {
+		hid_err(hdev, "Failed to register elan input device: %d\n",
+			ret);
+		input_free_device(input);
+		return ret;
+	}
+
+	drvdata->input = input;
+
+	return 0;
+}
+
+static void elan_report_mt_slot(struct elan_drvdata *drvdata, u8 *data,
+				unsigned int slot_num)
+{
+	struct input_dev *input = drvdata->input;
+	int x, y, w;
+
+	bool active = !!data;
+
+	input_mt_slot(input, slot_num);
+	input_mt_report_slot_state(input, MT_TOOL_FINGER, active);
+	if (active) {
+		x = ((data[0] & 0xF0) << 4) | data[1];
+		y = drvdata->settings->max_y -
+		    (((data[0] & 0x07) << 8) | data[2]);
+		w = data[4];
+
+		input_report_abs(input, ABS_MT_POSITION_X, x);
+		input_report_abs(input, ABS_MT_POSITION_Y, y);
+		input_report_abs(input, ABS_TOOL_WIDTH, w);
+	}
+}
+
+static void elan_report_input(struct elan_drvdata *drvdata, u8 *data)
+{
+	int i;
+	struct input_dev *input = drvdata->input;
+
+	/*
+	 * There is 3 types of reports: for single touch,
+	 * for multitouch - first finger and for multitouch - second finger
+	 *
+	 * packet structure for ELAN_SINGLE_FINGER and ELAN_MT_FIRST_FINGER:
+	 *
+	 * byte 1: 1   0   0   0   0   0   0   1  // 0x81 or 0x82
+	 * byte 2: 0   0   0   0   0   0   0   0  // looks like unused
+	 * byte 3: f5  f4  f3  f2  f1  0   0   L
+	 * byte 4: x12 x11 x10 x9  0?  y11 y10 y9
+	 * byte 5: x8  x7  x6  x5  x4  x3  x2  x1
+	 * byte 6: y8  y7  y6  y5  y4  y3  y2  y1
+	 * byte 7: sy4 sy3 sy2 sy1 sx4 sx3 sx2 sx1
+	 * byte 8: w8  w7  w6  w5  w4  w3  w2  w1
+	 *
+	 * packet structure for ELAN_MT_SECOND_FINGER:
+	 *
+	 * byte 1: 1   0   0   0   0   0   1   1  // 0x83
+	 * byte 2: x12 x11 x10 x9  0   y11 y10 y9
+	 * byte 3: x8  x7  x6  x5  x4  x3  x2  x1
+	 * byte 4: y8  y7  y6  y5  y4  y3  y2  y1
+	 * byte 5: sy4 sy3 sy2 sy1 sx4 sx3 sx2 sx1
+	 * byte 6: w8  w7  w6  w5  w4  w3  w2  w1
+	 * byte 7: 0   0   0   0   0   0   0   0
+	 * byte 8: 0   0   0   0   0   0   0   0
+	 *
+	 * f5-f1: finger touch bits
+	 * L: clickpad button
+	 * sy / sx: not sure yet, but this looks like rectangular
+	 * area for finger
+	 * w: looks like finger width
+	 */
+
+	if (data[0] == ELAN_SINGLE_FINGER) {
+		for (i = 0; i < drvdata->settings->max_fingers; i++) {
+			if (data[2] & BIT(i + 3))
+				elan_report_mt_slot(drvdata, data + 3, i);
+			else
+				elan_report_mt_slot(drvdata, NULL, i);
+		}
+		input_report_key(input, BTN_LEFT, data[2] & 0x01);
+	}
+	/*
+	 * When touched with two fingers Elan touchpad will emit two HID reports
+	 * first is ELAN_MT_FIRST_FINGER and second is ELAN_MT_SECOND_FINGER
+	 * we will save ELAN_MT_FIRST_FINGER report and wait for
+	 * ELAN_MT_SECOND_FINGER to finish multitouch
+	 */
+	if (data[0] == ELAN_MT_FIRST_FINGER) {
+		memcpy(drvdata->prev_report, data,
+		       sizeof(drvdata->prev_report));
+		return;
+	}
+
+	if (data[0] == ELAN_MT_SECOND_FINGER) {
+		int first = 0;
+		u8 *prev_report = drvdata->prev_report;
+
+		if (prev_report[0] != ELAN_MT_FIRST_FINGER)
+			return;
+
+		for (i = 0; i < drvdata->settings->max_fingers; i++) {
+			if (prev_report[2] & BIT(i + 3)) {
+				if (!first) {
+					first = 1;
+					elan_report_mt_slot(drvdata, prev_report + 3, i);
+				} else {
+					elan_report_mt_slot(drvdata, data + 1, i);
+				}
+			} else {
+				elan_report_mt_slot(drvdata, NULL, i);
+			}
+		}
+		input_report_key(input, BTN_LEFT, prev_report[2] & 0x01);
+	}
+
+	input_mt_sync_frame(input);
+	input_sync(input);
+}
+
+static int elan_raw_event(struct hid_device *hdev,
+			  struct hid_report *report, u8 *data, int size)
+{
+	struct elan_drvdata *drvdata = hid_get_drvdata(hdev);
+
+	if (is_not_elan_touchpad(hdev))
+		return 0;
+
+	if (data[0] == ELAN_SINGLE_FINGER ||
+	    data[0] == ELAN_MT_FIRST_FINGER ||
+	    data[0] == ELAN_MT_SECOND_FINGER) {
+		if (size == ELAN_INPUT_REPORT_SIZE) {
+			elan_report_input(drvdata, data);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static int elan_start_multitouch(struct hid_device *hdev)
+{
+	int ret;
+
+	/*
+	 * This byte sequence will enable multitouch mode and disable
+	 * mouse emulation
+	 */
+	const unsigned char buf[] = { 0x0D, 0x00, 0x03, 0x21, 0x00 };
+	unsigned char *dmabuf = kmemdup(buf, sizeof(buf), GFP_KERNEL);
+
+	if (!dmabuf)
+		return -ENOMEM;
+
+	ret = hid_hw_raw_request(hdev, dmabuf[0], dmabuf, sizeof(buf),
+				 HID_FEATURE_REPORT, HID_REQ_SET_REPORT);
+
+	kfree(dmabuf);
+
+	if (ret != sizeof(buf)) {
+		hid_err(hdev, "Failed to start multitouch: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static enum led_brightness elan_mute_led_get_brigtness(struct led_classdev *led_cdev)
+{
+	struct device *dev = led_cdev->dev->parent;
+	struct hid_device *hdev = to_hid_device(dev);
+	struct elan_drvdata *drvdata = hid_get_drvdata(hdev);
+
+	return drvdata->mute_led_state;
+}
+
+static int elan_mute_led_set_brigtness(struct led_classdev *led_cdev,
+				       enum led_brightness value)
+{
+	int ret;
+	u8 led_state;
+	struct device *dev = led_cdev->dev->parent;
+	struct hid_device *hdev = to_hid_device(dev);
+	struct elan_drvdata *drvdata = hid_get_drvdata(hdev);
+
+	unsigned char *dmabuf = kzalloc(ELAN_LED_REPORT_SIZE, GFP_KERNEL);
+
+	if (!dmabuf)
+		return -ENOMEM;
+
+	led_state = !!value;
+
+	dmabuf[0] = ELAN_MUTE_LED_REPORT;
+	dmabuf[1] = 0x02;
+	dmabuf[2] = led_state;
+
+	ret = hid_hw_raw_request(hdev, dmabuf[0], dmabuf, ELAN_LED_REPORT_SIZE,
+				 HID_FEATURE_REPORT, HID_REQ_SET_REPORT);
+
+	kfree(dmabuf);
+
+	if (ret != ELAN_LED_REPORT_SIZE) {
+		hid_err(hdev, "Failed to set mute led brightness: %d\n", ret);
+		return ret;
+	}
+
+	drvdata->mute_led_state = led_state;
+	return 0;
+}
+
+static int elan_init_mute_led(struct hid_device *hdev)
+{
+	struct elan_drvdata *drvdata = hid_get_drvdata(hdev);
+	struct led_classdev *mute_led = &drvdata->mute_led;
+
+	mute_led->name = "elan:red:mute";
+	mute_led->brightness_get = elan_mute_led_get_brigtness;
+	mute_led->brightness_set_blocking = elan_mute_led_set_brigtness;
+	mute_led->max_brightness = LED_ON;
+	mute_led->dev = &hdev->dev;
+
+	return devm_led_classdev_register(&hdev->dev, mute_led);
+}
+
+static int elan_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	int ret;
+	struct elan_drvdata *drvdata;
+
+	drvdata = devm_kzalloc(&hdev->dev, sizeof(*drvdata), GFP_KERNEL);
+
+	if (!drvdata)
+		return -ENOMEM;
+
+	drvdata->settings = (struct elan_touchpad_settings *)id->driver_data;
+	hid_set_drvdata(hdev, drvdata);
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "Hid Parse failed\n");
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "Hid hw start failed\n");
+		return ret;
+	}
+
+	if (is_not_elan_touchpad(hdev))
+		return 0;
+
+	if (!drvdata->input) {
+		hid_err(hdev, "Input device is not registred\n");
+		ret = -ENAVAIL;
+		goto err;
+	}
+
+	ret = elan_start_multitouch(hdev);
+	if (ret)
+		goto err;
+
+	ret = elan_init_mute_led(hdev);
+	if (ret)
+		goto err;
+
+	return 0;
+err:
+	hid_hw_stop(hdev);
+	return ret;
+}
+
+static void elan_remove(struct hid_device *hdev)
+{
+	hid_hw_stop(hdev);
+}
+
+static const struct elan_touchpad_settings hp_x2_10_touchpad_data = {
+	.max_fingers = 5,
+	.max_x = 2930,
+	.max_y = 1250,
+	.max_area_x = 15,
+	.max_area_y = 15,
+	.max_w = 255,
+	.usb_bInterfaceNumber = 1,
+};
+
+static const struct hid_device_id elan_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELAN, USB_DEVICE_ID_HP_X2_10_COVER),
+		(kernel_ulong_t)&hp_x2_10_touchpad_data},
+	{ }
+};
+
+MODULE_DEVICE_TABLE(hid, elan_devices);
+
+static struct hid_driver elan_driver = {
+	.name = "elan",
+	.id_table = elan_devices,
+	.input_mapping = elan_input_mapping,
+	.input_configured = elan_input_configured,
+	.raw_event = elan_raw_event,
+	.probe = elan_probe,
+	.remove = elan_remove,
+};
+
+module_hid_driver(elan_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Alexandrov Stanislav");
+MODULE_DESCRIPTION("Driver for HID ELAN Touchpads");