// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * HID Driver for ELAN Touchpad
 *
 * Currently only supports touchpad found on HP Pavilion X2 10
 *
 * Copyright (c) 2016 Alexandrov Stanislav <neko@nya.ai>
 */

#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_MT_I2C             0x5d
#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_I2C_REPORT_SIZE    32
#define ELAN_FINGER_DATA_LEN    5
#define ELAN_MAX_FINGERS        5
#define ELAN_MAX_PRESSURE       255
#define ELAN_TP_USB_INTF        1

#define ELAN_FEATURE_REPORT     0x0d
#define ELAN_FEATURE_SIZE       5
#define ELAN_PARAM_MAX_X        6
#define ELAN_PARAM_MAX_Y        7
#define ELAN_PARAM_RES          8

#define ELAN_MUTE_LED_REPORT    0xBC
#define ELAN_LED_REPORT_SIZE    8

#define ELAN_HAS_LED            BIT(0)

struct elan_drvdata {
        struct input_dev *input;
        u8 prev_report[ELAN_INPUT_REPORT_SIZE];
        struct led_classdev mute_led;
        u8 mute_led_state;
        u16 max_x;
        u16 max_y;
        u16 res_x;
        u16 res_y;
};

static int is_not_elan_touchpad(struct hid_device *hdev)
{
        if (hid_is_usb(hdev)) {
                struct usb_interface *intf = to_usb_interface(hdev->dev.parent);

                return (intf->altsetting->desc.bInterfaceNumber !=
                        ELAN_TP_USB_INTF);
        }

        return 0;
}

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 ||
            field->report->id == ELAN_MT_I2C)
                return -1;

        return 0;
}

static int elan_get_device_param(struct hid_device *hdev,
                                 unsigned char *dmabuf, unsigned char param)
{
        int ret;

        dmabuf[0] = ELAN_FEATURE_REPORT;
        dmabuf[1] = 0x05;
        dmabuf[2] = 0x03;
        dmabuf[3] = param;
        dmabuf[4] = 0x01;

        ret = hid_hw_raw_request(hdev, ELAN_FEATURE_REPORT, dmabuf,
                                 ELAN_FEATURE_SIZE, HID_FEATURE_REPORT,
                                 HID_REQ_SET_REPORT);
        if (ret != ELAN_FEATURE_SIZE) {
                hid_err(hdev, "Set report error for parm %d: %d\n", param, ret);
                return ret;
        }

        ret = hid_hw_raw_request(hdev, ELAN_FEATURE_REPORT, dmabuf,
                                 ELAN_FEATURE_SIZE, HID_FEATURE_REPORT,
                                 HID_REQ_GET_REPORT);
        if (ret != ELAN_FEATURE_SIZE) {
                hid_err(hdev, "Get report error for parm %d: %d\n", param, ret);
                return ret;
        }

        return 0;
}

static unsigned int elan_convert_res(char val)
{
        /*
         * (value from firmware) * 10 + 790 = dpi
         * dpi * 10 / 254 = dots/mm
         */
        return (val * 10 + 790) * 10 / 254;
}

static int elan_get_device_params(struct hid_device *hdev)
{
        struct elan_drvdata *drvdata = hid_get_drvdata(hdev);
        unsigned char *dmabuf;
        int ret;

        dmabuf = kmalloc(ELAN_FEATURE_SIZE, GFP_KERNEL);
        if (!dmabuf)
                return -ENOMEM;

        ret = elan_get_device_param(hdev, dmabuf, ELAN_PARAM_MAX_X);
        if (ret)
                goto err;

        drvdata->max_x = (dmabuf[4] << 8) | dmabuf[3];

        ret = elan_get_device_param(hdev, dmabuf, ELAN_PARAM_MAX_Y);
        if (ret)
                goto err;

        drvdata->max_y = (dmabuf[4] << 8) | dmabuf[3];

        ret = elan_get_device_param(hdev, dmabuf, ELAN_PARAM_RES);
        if (ret)
                goto err;

        drvdata->res_x = elan_convert_res(dmabuf[3]);
        drvdata->res_y = elan_convert_res(dmabuf[4]);

err:
        kfree(dmabuf);
        return ret;
}

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;

        ret = elan_get_device_params(hdev);
        if (ret)
                return ret;

        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->max_x,
                             0, 0);
        input_set_abs_params(input, ABS_MT_POSITION_Y, 0, drvdata->max_y,
                             0, 0);
        input_set_abs_params(input, ABS_MT_PRESSURE, 0, ELAN_MAX_PRESSURE,
                             0, 0);

        __set_bit(BTN_LEFT, input->keybit);
        __set_bit(INPUT_PROP_BUTTONPAD, input->propbit);

        ret = input_mt_init_slots(input, ELAN_MAX_FINGERS, INPUT_MT_POINTER);
        if (ret) {
                hid_err(hdev, "Failed to init elan MT slots: %d\n", ret);
                return ret;
        }

        input_abs_set_res(input, ABS_X, drvdata->res_x);
        input_abs_set_res(input, ABS_Y, drvdata->res_y);

        ret = input_register_device(input);
        if (ret) {
                hid_err(hdev, "Failed to register elan input device: %d\n",
                        ret);
                input_mt_destroy_slots(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, p;

        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->max_y -
                    (((data[0] & 0x07) << 8) | data[2]);
                p = 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_MT_PRESSURE, p);
        }
}

static void elan_usb_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: p8  p7  p6  p5  p4  p3  p2  p1
         *
         * 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: p8  p7  p6  p5  p4  p3  p2  p1
         * 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: finger width / height expressed in traces, the total number
         *          of traces can be queried by doing a HID_REQ_SET_REPORT
         *          { 0x0d, 0x05, 0x03, 0x05, 0x01 } followed by a GET, in the
         *          returned buf, buf[3]=no-x-traces, buf[4]=no-y-traces.
         * p: pressure
         */

        if (data[0] == ELAN_SINGLE_FINGER) {
                for (i = 0; i < ELAN_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 < ELAN_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 void elan_i2c_report_input(struct elan_drvdata *drvdata, u8 *data)
{
        struct input_dev *input = drvdata->input;
        u8 *finger_data;
        int i;

        /*
         * Elan MT touchpads in i2c mode send finger data in the same format
         * as in USB mode, but then with all fingers in a single packet.
         *
         * packet structure for ELAN_MT_I2C:
         *
         * byte     1: 1   0   0   1   1   1   0   1   // 0x5d
         * byte     2: f5  f4  f3  f2  f1  0   0   L
         * byte     3: x12 x11 x10 x9  0?  y11 y10 y9
         * byte     4: x8  x7  x6  x5  x4  x3  x2  x1
         * byte     5: y8  y7  y6  y5  y4  y3  y2  y1
         * byte     6: sy4 sy3 sy2 sy1 sx4 sx3 sx2 sx1
         * byte     7: p8  p7  p6  p5  p4  p3  p2  p1
         * byte  8-12: Same as byte 3-7 for second finger down
         * byte 13-17: Same as byte 3-7 for third finger down
         * byte 18-22: Same as byte 3-7 for fourth finger down
         * byte 23-27: Same as byte 3-7 for fifth finger down
         */

        finger_data = data + 2;
        for (i = 0; i < ELAN_MAX_FINGERS; i++) {
                if (data[1] & BIT(i + 3)) {
                        elan_report_mt_slot(drvdata, finger_data, i);
                        finger_data += ELAN_FINGER_DATA_LEN;
                } else {
                        elan_report_mt_slot(drvdata, NULL, i);
                }
        }

        input_report_key(input, BTN_LEFT, data[1] & 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_usb_report_input(drvdata, data);
                        return 1;
                }
        }

        if (data[0] == ELAN_MT_I2C && size == ELAN_I2C_REPORT_SIZE) {
                elan_i2c_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
         */
        static 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 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) {
                if (ret != -ENODEV)
                        hid_err(hdev, "Failed to set mute led brightness: %d\n", ret);
                return ret < 0 ? ret : -EIO;
        }

        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->default_trigger = "audio-mute";
        mute_led->brightness_set_blocking = elan_mute_led_set_brigtness;
        mute_led->max_brightness = LED_ON;
        mute_led->flags = LED_HW_PLUGGABLE;
        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;

        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 registered\n");
                ret = -ENAVAIL;
                goto err;
        }

        ret = elan_start_multitouch(hdev);
        if (ret)
                goto err;

        if (id->driver_data & ELAN_HAS_LED) {
                ret = elan_init_mute_led(hdev);
                if (ret)
                        goto err;
        }

        return 0;
err:
        hid_hw_stop(hdev);
        return ret;
}

static const struct hid_device_id elan_devices[] = {
        { HID_USB_DEVICE(USB_VENDOR_ID_ELAN, USB_DEVICE_ID_HP_X2),
          .driver_data = ELAN_HAS_LED },
        { HID_USB_DEVICE(USB_VENDOR_ID_ELAN, USB_DEVICE_ID_HP_X2_10_COVER),
          .driver_data = ELAN_HAS_LED },
        { HID_I2C_DEVICE(USB_VENDOR_ID_ELAN, USB_DEVICE_ID_TOSHIBA_CLICK_L9W) },
        { }
};
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,
};

module_hid_driver(elan_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alexandrov Stanislav");
MODULE_DESCRIPTION("Driver for HID ELAN Touchpads");