/*
 * Elantech Touchpad driver (v6)
 *
 * Copyright (C) 2007-2009 Arjan Opmeer <arjan@opmeer.net>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * Trademarks are the property of their respective owners.
 */

#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/input/mt.h>
#include <linux/serio.h>
#include <linux/libps2.h>
#include "psmouse.h"
#include "elantech.h"

#define elantech_debug(fmt, ...)                                        \
        do {                                                            \
                if (etd->debug)                                         \
                        psmouse_printk(KERN_DEBUG, psmouse,             \
                                        fmt, ##__VA_ARGS__);            \
        } while (0)

/*
 * Send a Synaptics style sliced query command
 */
static int synaptics_send_cmd(struct psmouse *psmouse, unsigned char c,
                                unsigned char *param)
{
        if (psmouse_sliced_command(psmouse, c) ||
            ps2_command(&psmouse->ps2dev, param, PSMOUSE_CMD_GETINFO)) {
                psmouse_err(psmouse, "%s query 0x%02x failed.\n", __func__, c);
                return -1;
        }

        return 0;
}

/*
 * V3 and later support this fast command
 */
static int elantech_send_cmd(struct psmouse *psmouse, unsigned char c,
                                unsigned char *param)
{
        struct ps2dev *ps2dev = &psmouse->ps2dev;

        if (ps2_command(ps2dev, NULL, ETP_PS2_CUSTOM_COMMAND) ||
            ps2_command(ps2dev, NULL, c) ||
            ps2_command(ps2dev, param, PSMOUSE_CMD_GETINFO)) {
                psmouse_err(psmouse, "%s query 0x%02x failed.\n", __func__, c);
                return -1;
        }

        return 0;
}

/*
 * A retrying version of ps2_command
 */
static int elantech_ps2_command(struct psmouse *psmouse,
                                unsigned char *param, int command)
{
        struct ps2dev *ps2dev = &psmouse->ps2dev;
        struct elantech_data *etd = psmouse->private;
        int rc;
        int tries = ETP_PS2_COMMAND_TRIES;

        do {
                rc = ps2_command(ps2dev, param, command);
                if (rc == 0)
                        break;
                tries--;
                elantech_debug("retrying ps2 command 0x%02x (%d).\n",
                                command, tries);
                msleep(ETP_PS2_COMMAND_DELAY);
        } while (tries > 0);

        if (rc)
                psmouse_err(psmouse, "ps2 command 0x%02x failed.\n", command);

        return rc;
}

/*
 * Send an Elantech style special command to read a value from a register
 */
static int elantech_read_reg(struct psmouse *psmouse, unsigned char reg,
                                unsigned char *val)
{
        struct elantech_data *etd = psmouse->private;
        unsigned char param[3];
        int rc = 0;

        if (reg < 0x07 || reg > 0x26)
                return -1;

        if (reg > 0x11 && reg < 0x20)
                return -1;

        switch (etd->hw_version) {
        case 1:
                if (psmouse_sliced_command(psmouse, ETP_REGISTER_READ) ||
                    psmouse_sliced_command(psmouse, reg) ||
                    ps2_command(&psmouse->ps2dev, param, PSMOUSE_CMD_GETINFO)) {
                        rc = -1;
                }
                break;

        case 2:
                if (elantech_ps2_command(psmouse,  NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse,  NULL, ETP_REGISTER_READ) ||
                    elantech_ps2_command(psmouse,  NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse,  NULL, reg) ||
                    elantech_ps2_command(psmouse, param, PSMOUSE_CMD_GETINFO)) {
                        rc = -1;
                }
                break;

        case 3 ... 4:
                if (elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_READWRITE) ||
                    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, reg) ||
                    elantech_ps2_command(psmouse, param, PSMOUSE_CMD_GETINFO)) {
                        rc = -1;
                }
                break;
        }

        if (rc)
                psmouse_err(psmouse, "failed to read register 0x%02x.\n", reg);
        else if (etd->hw_version != 4)
                *val = param[0];
        else
                *val = param[1];

        return rc;
}

/*
 * Send an Elantech style special command to write a register with a value
 */
static int elantech_write_reg(struct psmouse *psmouse, unsigned char reg,
                                unsigned char val)
{
        struct elantech_data *etd = psmouse->private;
        int rc = 0;

        if (reg < 0x07 || reg > 0x26)
                return -1;

        if (reg > 0x11 && reg < 0x20)
                return -1;

        switch (etd->hw_version) {
        case 1:
                if (psmouse_sliced_command(psmouse, ETP_REGISTER_WRITE) ||
                    psmouse_sliced_command(psmouse, reg) ||
                    psmouse_sliced_command(psmouse, val) ||
                    ps2_command(&psmouse->ps2dev, NULL, PSMOUSE_CMD_SETSCALE11)) {
                        rc = -1;
                }
                break;

        case 2:
                if (elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_WRITE) ||
                    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, reg) ||
                    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, val) ||
                    elantech_ps2_command(psmouse, NULL, PSMOUSE_CMD_SETSCALE11)) {
                        rc = -1;
                }
                break;

        case 3:
                if (elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_READWRITE) ||
                    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, reg) ||
                    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, val) ||
                    elantech_ps2_command(psmouse, NULL, PSMOUSE_CMD_SETSCALE11)) {
                        rc = -1;
                }
                break;

        case 4:
                if (elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_READWRITE) ||
                    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, reg) ||
                    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, ETP_REGISTER_READWRITE) ||
                    elantech_ps2_command(psmouse, NULL, ETP_PS2_CUSTOM_COMMAND) ||
                    elantech_ps2_command(psmouse, NULL, val) ||
                    elantech_ps2_command(psmouse, NULL, PSMOUSE_CMD_SETSCALE11)) {
                        rc = -1;
                }
                break;
        }

        if (rc)
                psmouse_err(psmouse,
                            "failed to write register 0x%02x with value 0x%02x.\n",
                            reg, val);

        return rc;
}

/*
 * Dump a complete mouse movement packet to the syslog
 */
static void elantech_packet_dump(struct psmouse *psmouse)
{
        int     i;

        psmouse_printk(KERN_DEBUG, psmouse, "PS/2 packet [");
        for (i = 0; i < psmouse->pktsize; i++)
                printk("%s0x%02x ", i ? ", " : " ", psmouse->packet[i]);
        printk("]\n");
}

/*
 * Interpret complete data packets and report absolute mode input events for
 * hardware version 1. (4 byte packets)
 */
static void elantech_report_absolute_v1(struct psmouse *psmouse)
{
        struct input_dev *dev = psmouse->dev;
        struct elantech_data *etd = psmouse->private;
        unsigned char *packet = psmouse->packet;
        int fingers;

        if (etd->fw_version < 0x020000) {
                /*
                 * byte 0:  D   U  p1  p2   1  p3   R   L
                 * byte 1:  f   0  th  tw  x9  x8  y9  y8
                 */
                fingers = ((packet[1] & 0x80) >> 7) +
                                ((packet[1] & 0x30) >> 4);
        } else {
                /*
                 * byte 0: n1  n0  p2  p1   1  p3   R   L
                 * byte 1:  0   0   0   0  x9  x8  y9  y8
                 */
                fingers = (packet[0] & 0xc0) >> 6;
        }

        if (etd->jumpy_cursor) {
                if (fingers != 1) {
                        etd->single_finger_reports = 0;
                } else if (etd->single_finger_reports < 2) {
                        /* Discard first 2 reports of one finger, bogus */
                        etd->single_finger_reports++;
                        elantech_debug("discarding packet\n");
                        return;
                }
        }

        input_report_key(dev, BTN_TOUCH, fingers != 0);

        /*
         * byte 2: x7  x6  x5  x4  x3  x2  x1  x0
         * byte 3: y7  y6  y5  y4  y3  y2  y1  y0
         */
        if (fingers) {
                input_report_abs(dev, ABS_X,
                        ((packet[1] & 0x0c) << 6) | packet[2]);
                input_report_abs(dev, ABS_Y,
                        etd->y_max - (((packet[1] & 0x03) << 8) | packet[3]));
        }

        input_report_key(dev, BTN_TOOL_FINGER, fingers == 1);
        input_report_key(dev, BTN_TOOL_DOUBLETAP, fingers == 2);
        input_report_key(dev, BTN_TOOL_TRIPLETAP, fingers == 3);
        input_report_key(dev, BTN_LEFT, packet[0] & 0x01);
        input_report_key(dev, BTN_RIGHT, packet[0] & 0x02);

        if (etd->fw_version < 0x020000 &&
            (etd->capabilities[0] & ETP_CAP_HAS_ROCKER)) {
                /* rocker up */
                input_report_key(dev, BTN_FORWARD, packet[0] & 0x40);
                /* rocker down */
                input_report_key(dev, BTN_BACK, packet[0] & 0x80);
        }

        input_sync(dev);
}

static void elantech_set_slot(struct input_dev *dev, int slot, bool active,
                              unsigned int x, unsigned int y)
{
        input_mt_slot(dev, slot);
        input_mt_report_slot_state(dev, MT_TOOL_FINGER, active);
        if (active) {
                input_report_abs(dev, ABS_MT_POSITION_X, x);
                input_report_abs(dev, ABS_MT_POSITION_Y, y);
        }
}

/* x1 < x2 and y1 < y2 when two fingers, x = y = 0 when not pressed */
static void elantech_report_semi_mt_data(struct input_dev *dev,
                                         unsigned int num_fingers,
                                         unsigned int x1, unsigned int y1,
                                         unsigned int x2, unsigned int y2)
{
        elantech_set_slot(dev, 0, num_fingers != 0, x1, y1);
        elantech_set_slot(dev, 1, num_fingers == 2, x2, y2);
}

/*
 * Interpret complete data packets and report absolute mode input events for
 * hardware version 2. (6 byte packets)
 */
static void elantech_report_absolute_v2(struct psmouse *psmouse)
{
        struct elantech_data *etd = psmouse->private;
        struct input_dev *dev = psmouse->dev;
        unsigned char *packet = psmouse->packet;
        unsigned int fingers, x1 = 0, y1 = 0, x2 = 0, y2 = 0;
        unsigned int width = 0, pres = 0;

        /* byte 0: n1  n0   .   .   .   .   R   L */
        fingers = (packet[0] & 0xc0) >> 6;

        switch (fingers) {
        case 3:
                /*
                 * Same as one finger, except report of more than 3 fingers:
                 * byte 3:  n4  .   w1  w0   .   .   .   .
                 */
                if (packet[3] & 0x80)
                        fingers = 4;
                /* pass through... */
        case 1:
                /*
                 * byte 1:  .   .   .   .  x11 x10 x9  x8
                 * byte 2: x7  x6  x5  x4  x4  x2  x1  x0
                 */
                x1 = ((packet[1] & 0x0f) << 8) | packet[2];
                /*
                 * byte 4:  .   .   .   .  y11 y10 y9  y8
                 * byte 5: y7  y6  y5  y4  y3  y2  y1  y0
                 */
                y1 = etd->y_max - (((packet[4] & 0x0f) << 8) | packet[5]);

                pres = (packet[1] & 0xf0) | ((packet[4] & 0xf0) >> 4);
                width = ((packet[0] & 0x30) >> 2) | ((packet[3] & 0x30) >> 4);
                break;

        case 2:
                /*
                 * The coordinate of each finger is reported separately
                 * with a lower resolution for two finger touches:
                 * byte 0:  .   .  ay8 ax8  .   .   .   .
                 * byte 1: ax7 ax6 ax5 ax4 ax3 ax2 ax1 ax0
                 */
                x1 = (((packet[0] & 0x10) << 4) | packet[1]) << 2;
                /* byte 2: ay7 ay6 ay5 ay4 ay3 ay2 ay1 ay0 */
                y1 = etd->y_max -
                        ((((packet[0] & 0x20) << 3) | packet[2]) << 2);
                /*
                 * byte 3:  .   .  by8 bx8  .   .   .   .
                 * byte 4: bx7 bx6 bx5 bx4 bx3 bx2 bx1 bx0
                 */
                x2 = (((packet[3] & 0x10) << 4) | packet[4]) << 2;
                /* byte 5: by7 by8 by5 by4 by3 by2 by1 by0 */
                y2 = etd->y_max -
                        ((((packet[3] & 0x20) << 3) | packet[5]) << 2);

                /* Unknown so just report sensible values */
                pres = 127;
                width = 7;
                break;
        }

        input_report_key(dev, BTN_TOUCH, fingers != 0);
        if (fingers != 0) {
                input_report_abs(dev, ABS_X, x1);
                input_report_abs(dev, ABS_Y, y1);
        }
        elantech_report_semi_mt_data(dev, fingers, x1, y1, x2, y2);
        input_report_key(dev, BTN_TOOL_FINGER, fingers == 1);
        input_report_key(dev, BTN_TOOL_DOUBLETAP, fingers == 2);
        input_report_key(dev, BTN_TOOL_TRIPLETAP, fingers == 3);
        input_report_key(dev, BTN_TOOL_QUADTAP, fingers == 4);
        input_report_key(dev, BTN_LEFT, packet[0] & 0x01);
        input_report_key(dev, BTN_RIGHT, packet[0] & 0x02);
        if (etd->reports_pressure) {
                input_report_abs(dev, ABS_PRESSURE, pres);
                input_report_abs(dev, ABS_TOOL_WIDTH, width);
        }

        input_sync(dev);
}

/*
 * Interpret complete data packets and report absolute mode input events for
 * hardware version 3. (12 byte packets for two fingers)
 */
static void elantech_report_absolute_v3(struct psmouse *psmouse,
                                        int packet_type)
{
        struct input_dev *dev = psmouse->dev;
        struct elantech_data *etd = psmouse->private;
        unsigned char *packet = psmouse->packet;
        unsigned int fingers = 0, x1 = 0, y1 = 0, x2 = 0, y2 = 0;
        unsigned int width = 0, pres = 0;

        /* byte 0: n1  n0   .   .   .   .   R   L */
        fingers = (packet[0] & 0xc0) >> 6;

        switch (fingers) {
        case 3:
        case 1:
                /*
                 * byte 1:  .   .   .   .  x11 x10 x9  x8
                 * byte 2: x7  x6  x5  x4  x4  x2  x1  x0
                 */
                x1 = ((packet[1] & 0x0f) << 8) | packet[2];
                /*
                 * byte 4:  .   .   .   .  y11 y10 y9  y8
                 * byte 5: y7  y6  y5  y4  y3  y2  y1  y0
                 */
                y1 = etd->y_max - (((packet[4] & 0x0f) << 8) | packet[5]);
                break;

        case 2:
                if (packet_type == PACKET_V3_HEAD) {
                        /*
                         * byte 1:   .    .    .    .  ax11 ax10 ax9  ax8
                         * byte 2: ax7  ax6  ax5  ax4  ax3  ax2  ax1  ax0
                         */
                        etd->mt[0].x = ((packet[1] & 0x0f) << 8) | packet[2];
                        /*
                         * byte 4:   .    .    .    .  ay11 ay10 ay9  ay8
                         * byte 5: ay7  ay6  ay5  ay4  ay3  ay2  ay1  ay0
                         */
                        etd->mt[0].y = etd->y_max -
                                (((packet[4] & 0x0f) << 8) | packet[5]);
                        /*
                         * wait for next packet
                         */
                        return;
                }

                /* packet_type == PACKET_V3_TAIL */
                x1 = etd->mt[0].x;
                y1 = etd->mt[0].y;
                x2 = ((packet[1] & 0x0f) << 8) | packet[2];
                y2 = etd->y_max - (((packet[4] & 0x0f) << 8) | packet[5]);
                break;
        }

        pres = (packet[1] & 0xf0) | ((packet[4] & 0xf0) >> 4);
        width = ((packet[0] & 0x30) >> 2) | ((packet[3] & 0x30) >> 4);

        input_report_key(dev, BTN_TOUCH, fingers != 0);
        if (fingers != 0) {
                input_report_abs(dev, ABS_X, x1);
                input_report_abs(dev, ABS_Y, y1);
        }
        elantech_report_semi_mt_data(dev, fingers, x1, y1, x2, y2);
        input_report_key(dev, BTN_TOOL_FINGER, fingers == 1);
        input_report_key(dev, BTN_TOOL_DOUBLETAP, fingers == 2);
        input_report_key(dev, BTN_TOOL_TRIPLETAP, fingers == 3);
        input_report_key(dev, BTN_LEFT, packet[0] & 0x01);
        input_report_key(dev, BTN_RIGHT, packet[0] & 0x02);
        input_report_abs(dev, ABS_PRESSURE, pres);
        input_report_abs(dev, ABS_TOOL_WIDTH, width);

        input_sync(dev);
}

static void elantech_input_sync_v4(struct psmouse *psmouse)
{
        struct input_dev *dev = psmouse->dev;
        unsigned char *packet = psmouse->packet;

        input_report_key(dev, BTN_LEFT, packet[0] & 0x01);
        input_mt_report_pointer_emulation(dev, true);
        input_sync(dev);
}

static void process_packet_status_v4(struct psmouse *psmouse)
{
        struct input_dev *dev = psmouse->dev;
        unsigned char *packet = psmouse->packet;
        unsigned fingers;
        int i;

        /* notify finger state change */
        fingers = packet[1] & 0x1f;
        for (i = 0; i < ETP_MAX_FINGERS; i++) {
                if ((fingers & (1 << i)) == 0) {
                        input_mt_slot(dev, i);
                        input_mt_report_slot_state(dev, MT_TOOL_FINGER, false);
                }
        }

        elantech_input_sync_v4(psmouse);
}

static void process_packet_head_v4(struct psmouse *psmouse)
{
        struct input_dev *dev = psmouse->dev;
        struct elantech_data *etd = psmouse->private;
        unsigned char *packet = psmouse->packet;
        int id = ((packet[3] & 0xe0) >> 5) - 1;
        int pres, traces;

        if (id < 0)
                return;

        etd->mt[id].x = ((packet[1] & 0x0f) << 8) | packet[2];
        etd->mt[id].y = etd->y_max - (((packet[4] & 0x0f) << 8) | packet[5]);
        pres = (packet[1] & 0xf0) | ((packet[4] & 0xf0) >> 4);
        traces = (packet[0] & 0xf0) >> 4;

        input_mt_slot(dev, id);
        input_mt_report_slot_state(dev, MT_TOOL_FINGER, true);

        input_report_abs(dev, ABS_MT_POSITION_X, etd->mt[id].x);
        input_report_abs(dev, ABS_MT_POSITION_Y, etd->mt[id].y);
        input_report_abs(dev, ABS_MT_PRESSURE, pres);
        input_report_abs(dev, ABS_MT_TOUCH_MAJOR, traces * etd->width);
        /* report this for backwards compatibility */
        input_report_abs(dev, ABS_TOOL_WIDTH, traces);

        elantech_input_sync_v4(psmouse);
}

static void process_packet_motion_v4(struct psmouse *psmouse)
{
        struct input_dev *dev = psmouse->dev;
        struct elantech_data *etd = psmouse->private;
        unsigned char *packet = psmouse->packet;
        int weight, delta_x1 = 0, delta_y1 = 0, delta_x2 = 0, delta_y2 = 0;
        int id, sid;

        id = ((packet[0] & 0xe0) >> 5) - 1;
        if (id < 0)
                return;

        sid = ((packet[3] & 0xe0) >> 5) - 1;
        weight = (packet[0] & 0x10) ? ETP_WEIGHT_VALUE : 1;
        /*
         * Motion packets give us the delta of x, y values of specific fingers,
         * but in two's complement. Let the compiler do the conversion for us.
         * Also _enlarge_ the numbers to int, in case of overflow.
         */
        delta_x1 = (signed char)packet[1];
        delta_y1 = (signed char)packet[2];
        delta_x2 = (signed char)packet[4];
        delta_y2 = (signed char)packet[5];

        etd->mt[id].x += delta_x1 * weight;
        etd->mt[id].y -= delta_y1 * weight;
        input_mt_slot(dev, id);
        input_report_abs(dev, ABS_MT_POSITION_X, etd->mt[id].x);
        input_report_abs(dev, ABS_MT_POSITION_Y, etd->mt[id].y);

        if (sid >= 0) {
                etd->mt[sid].x += delta_x2 * weight;
                etd->mt[sid].y -= delta_y2 * weight;
                input_mt_slot(dev, sid);
                input_report_abs(dev, ABS_MT_POSITION_X, etd->mt[sid].x);
                input_report_abs(dev, ABS_MT_POSITION_Y, etd->mt[sid].y);
        }

        elantech_input_sync_v4(psmouse);
}

static void elantech_report_absolute_v4(struct psmouse *psmouse,
                                        int packet_type)
{
        switch (packet_type) {
        case PACKET_V4_STATUS:
                process_packet_status_v4(psmouse);
                break;

        case PACKET_V4_HEAD:
                process_packet_head_v4(psmouse);
                break;

        case PACKET_V4_MOTION:
                process_packet_motion_v4(psmouse);
                break;

        case PACKET_UNKNOWN:
        default:
                /* impossible to get here */
                break;
        }
}

static int elantech_packet_check_v1(struct psmouse *psmouse)
{
        struct elantech_data *etd = psmouse->private;
        unsigned char *packet = psmouse->packet;
        unsigned char p1, p2, p3;

        /* Parity bits are placed differently */
        if (etd->fw_version < 0x020000) {
                /* byte 0:  D   U  p1  p2   1  p3   R   L */
                p1 = (packet[0] & 0x20) >> 5;
                p2 = (packet[0] & 0x10) >> 4;
        } else {
                /* byte 0: n1  n0  p2  p1   1  p3   R   L */
                p1 = (packet[0] & 0x10) >> 4;
                p2 = (packet[0] & 0x20) >> 5;
        }

        p3 = (packet[0] & 0x04) >> 2;

        return etd->parity[packet[1]] == p1 &&
               etd->parity[packet[2]] == p2 &&
               etd->parity[packet[3]] == p3;
}

static int elantech_debounce_check_v2(struct psmouse *psmouse)
{
        /*
         * When we encounter packet that matches this exactly, it means the
         * hardware is in debounce status. Just ignore the whole packet.
         */
        const u8 debounce_packet[] = { 0x84, 0xff, 0xff, 0x02, 0xff, 0xff };
        unsigned char *packet = psmouse->packet;

        return !memcmp(packet, debounce_packet, sizeof(debounce_packet));
}

static int elantech_packet_check_v2(struct psmouse *psmouse)
{
        struct elantech_data *etd = psmouse->private;
        unsigned char *packet = psmouse->packet;

        /*
         * V2 hardware has two flavors. Older ones that do not report pressure,
         * and newer ones that reports pressure and width. With newer ones, all
         * packets (1, 2, 3 finger touch) have the same constant bits. With
         * older ones, 1/3 finger touch packets and 2 finger touch packets
         * have different constant bits.
         * With all three cases, if the constant bits are not exactly what I
         * expected, I consider them invalid.
         */
        if (etd->reports_pressure)
                return (packet[0] & 0x0c) == 0x04 &&
                       (packet[3] & 0x0f) == 0x02;

        if ((packet[0] & 0xc0) == 0x80)
                return (packet[0] & 0x0c) == 0x0c &&
                       (packet[3] & 0x0e) == 0x08;

        return (packet[0] & 0x3c) == 0x3c &&
               (packet[1] & 0xf0) == 0x00 &&
               (packet[3] & 0x3e) == 0x38 &&
               (packet[4] & 0xf0) == 0x00;
}

/*
 * We check the constant bits to determine what packet type we get,
 * so packet checking is mandatory for v3 and later hardware.
 */
static int elantech_packet_check_v3(struct psmouse *psmouse)
{
        struct elantech_data *etd = psmouse->private;
        const u8 debounce_packet[] = { 0xc4, 0xff, 0xff, 0x02, 0xff, 0xff };
        unsigned char *packet = psmouse->packet;

        /*
         * check debounce first, it has the same signature in byte 0
         * and byte 3 as PACKET_V3_HEAD.
         */
        if (!memcmp(packet, debounce_packet, sizeof(debounce_packet)))
                return PACKET_DEBOUNCE;

        /*
         * If the hardware flag 'crc_enabled' is set the packets have
         * different signatures.
         */
        if (etd->crc_enabled) {
                if ((packet[3] & 0x09) == 0x08)
                        return PACKET_V3_HEAD;

                if ((packet[3] & 0x09) == 0x09)
                        return PACKET_V3_TAIL;
        } else {
                if ((packet[0] & 0x0c) == 0x04 && (packet[3] & 0xcf) == 0x02)
                        return PACKET_V3_HEAD;

                if ((packet[0] & 0x0c) == 0x0c && (packet[3] & 0xce) == 0x0c)
                        return PACKET_V3_TAIL;
        }

        return PACKET_UNKNOWN;
}

static int elantech_packet_check_v4(struct psmouse *psmouse)
{
        struct elantech_data *etd = psmouse->private;
        unsigned char *packet = psmouse->packet;
        unsigned char packet_type = packet[3] & 0x03;
        bool sanity_check;

        /*
         * Sanity check based on the constant bits of a packet.
         * The constant bits change depending on the value of
         * the hardware flag 'crc_enabled' but are the same for
         * every packet, regardless of the type.
         */
        if (etd->crc_enabled)
                sanity_check = ((packet[3] & 0x08) == 0x00);
        else
                sanity_check = ((packet[0] & 0x0c) == 0x04 &&
                                (packet[3] & 0x1c) == 0x10);

        if (!sanity_check)
                return PACKET_UNKNOWN;

        switch (packet_type) {
        case 0:
                return PACKET_V4_STATUS;

        case 1:
                return PACKET_V4_HEAD;

        case 2:
                return PACKET_V4_MOTION;
        }

        return PACKET_UNKNOWN;
}

/*
 * Process byte stream from mouse and handle complete packets
 */
static psmouse_ret_t elantech_process_byte(struct psmouse *psmouse)
{
        struct elantech_data *etd = psmouse->private;
        int packet_type;

        if (psmouse->pktcnt < psmouse->pktsize)
                return PSMOUSE_GOOD_DATA;

        if (etd->debug > 1)
                elantech_packet_dump(psmouse);

        switch (etd->hw_version) {
        case 1:
                if (etd->paritycheck && !elantech_packet_check_v1(psmouse))
                        return PSMOUSE_BAD_DATA;

                elantech_report_absolute_v1(psmouse);
                break;

        case 2:
                /* ignore debounce */
                if (elantech_debounce_check_v2(psmouse))
                        return PSMOUSE_FULL_PACKET;

                if (etd->paritycheck && !elantech_packet_check_v2(psmouse))
                        return PSMOUSE_BAD_DATA;

                elantech_report_absolute_v2(psmouse);
                break;

        case 3:
                packet_type = elantech_packet_check_v3(psmouse);
                /* ignore debounce */
                if (packet_type == PACKET_DEBOUNCE)
                        return PSMOUSE_FULL_PACKET;

                if (packet_type == PACKET_UNKNOWN)
                        return PSMOUSE_BAD_DATA;

                elantech_report_absolute_v3(psmouse, packet_type);
                break;

        case 4:
                packet_type = elantech_packet_check_v4(psmouse);
                if (packet_type == PACKET_UNKNOWN)
                        return PSMOUSE_BAD_DATA;

                elantech_report_absolute_v4(psmouse, packet_type);
                break;
        }

        return PSMOUSE_FULL_PACKET;
}

/*
 * Put the touchpad into absolute mode
 */
static int elantech_set_absolute_mode(struct psmouse *psmouse)
{
        struct elantech_data *etd = psmouse->private;
        unsigned char val;
        int tries = ETP_READ_BACK_TRIES;
        int rc = 0;

        switch (etd->hw_version) {
        case 1:
                etd->reg_10 = 0x16;
                etd->reg_11 = 0x8f;
                if (elantech_write_reg(psmouse, 0x10, etd->reg_10) ||
                    elantech_write_reg(psmouse, 0x11, etd->reg_11)) {
                        rc = -1;
                }
                break;

        case 2:
                                        /* Windows driver values */
                etd->reg_10 = 0x54;
                etd->reg_11 = 0x88;     /* 0x8a */
                etd->reg_21 = 0x60;     /* 0x00 */
                if (elantech_write_reg(psmouse, 0x10, etd->reg_10) ||
                    elantech_write_reg(psmouse, 0x11, etd->reg_11) ||
                    elantech_write_reg(psmouse, 0x21, etd->reg_21)) {
                        rc = -1;
                }
                break;

        case 3:
                etd->reg_10 = 0x0b;
                if (elantech_write_reg(psmouse, 0x10, etd->reg_10))
                        rc = -1;

                break;

        case 4:
                etd->reg_07 = 0x01;
                if (elantech_write_reg(psmouse, 0x07, etd->reg_07))
                        rc = -1;

                goto skip_readback_reg_10; /* v4 has no reg 0x10 to read */
        }

        if (rc == 0) {
                /*
                 * Read back reg 0x10. For hardware version 1 we must make
                 * sure the absolute mode bit is set. For hardware version 2
                 * the touchpad is probably initializing and not ready until
                 * we read back the value we just wrote.
                 */
                do {
                        rc = elantech_read_reg(psmouse, 0x10, &val);
                        if (rc == 0)
                                break;
                        tries--;
                        elantech_debug("retrying read (%d).\n", tries);
                        msleep(ETP_READ_BACK_DELAY);
                } while (tries > 0);

                if (rc) {
                        psmouse_err(psmouse,
                                    "failed to read back register 0x10.\n");
                } else if (etd->hw_version == 1 &&
                           !(val & ETP_R10_ABSOLUTE_MODE)) {
                        psmouse_err(psmouse,
                                    "touchpad refuses to switch to absolute mode.\n");
                        rc = -1;
                }
        }

 skip_readback_reg_10:
        if (rc)
                psmouse_err(psmouse, "failed to initialise registers.\n");

        return rc;
}

static int elantech_set_range(struct psmouse *psmouse,
                              unsigned int *x_min, unsigned int *y_min,
                              unsigned int *x_max, unsigned int *y_max,
                              unsigned int *width)
{
        struct elantech_data *etd = psmouse->private;
        unsigned char param[3];
        unsigned char traces;

        switch (etd->hw_version) {
        case 1:
                *x_min = ETP_XMIN_V1;
                *y_min = ETP_YMIN_V1;
                *x_max = ETP_XMAX_V1;
                *y_max = ETP_YMAX_V1;
                break;

        case 2:
                if (etd->fw_version == 0x020800 ||
                    etd->fw_version == 0x020b00 ||
                    etd->fw_version == 0x020030) {
                        *x_min = ETP_XMIN_V2;
                        *y_min = ETP_YMIN_V2;
                        *x_max = ETP_XMAX_V2;
                        *y_max = ETP_YMAX_V2;
                } else {
                        int i;
                        int fixed_dpi;

                        i = (etd->fw_version > 0x020800 &&
                             etd->fw_version < 0x020900) ? 1 : 2;

                        if (etd->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
                                return -1;

                        fixed_dpi = param[1] & 0x10;

                        if (((etd->fw_version >> 16) == 0x14) && fixed_dpi) {
                                if (etd->send_cmd(psmouse, ETP_SAMPLE_QUERY, param))
                                        return -1;

                                *x_max = (etd->capabilities[1] - i) * param[1] / 2;
                                *y_max = (etd->capabilities[2] - i) * param[2] / 2;
                        } else if (etd->fw_version == 0x040216) {
                                *x_max = 819;
                                *y_max = 405;
                        } else if (etd->fw_version == 0x040219 || etd->fw_version == 0x040215) {
                                *x_max = 900;
                                *y_max = 500;
                        } else {
                                *x_max = (etd->capabilities[1] - i) * 64;
                                *y_max = (etd->capabilities[2] - i) * 64;
                        }
                }
                break;

        case 3:
                if (etd->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
                        return -1;

                *x_max = (0x0f & param[0]) << 8 | param[1];
                *y_max = (0xf0 & param[0]) << 4 | param[2];
                break;

        case 4:
                if (etd->send_cmd(psmouse, ETP_FW_ID_QUERY, param))
                        return -1;

                *x_max = (0x0f & param[0]) << 8 | param[1];
                *y_max = (0xf0 & param[0]) << 4 | param[2];
                traces = etd->capabilities[1];
                if ((traces < 2) || (traces > *x_max))
                        return -1;

                *width = *x_max / (traces - 1);
                break;
        }

        return 0;
}

/*
 * (value from firmware) * 10 + 790 = dpi
 * we also have to convert dpi to dots/mm (*10/254 to avoid floating point)
 */
static unsigned int elantech_convert_res(unsigned int val)
{
        return (val * 10 + 790) * 10 / 254;
}

static int elantech_get_resolution_v4(struct psmouse *psmouse,
                                      unsigned int *x_res,
                                      unsigned int *y_res)
{
        unsigned char param[3];

        if (elantech_send_cmd(psmouse, ETP_RESOLUTION_QUERY, param))
                return -1;

        *x_res = elantech_convert_res(param[1] & 0x0f);
        *y_res = elantech_convert_res((param[1] & 0xf0) >> 4);

        return 0;
}

/*
 * Set the appropriate event bits for the input subsystem
 */
static int elantech_set_input_params(struct psmouse *psmouse)
{
        struct input_dev *dev = psmouse->dev;
        struct elantech_data *etd = psmouse->private;
        unsigned int x_min = 0, y_min = 0, x_max = 0, y_max = 0, width = 0;
        unsigned int x_res = 0, y_res = 0;

        if (elantech_set_range(psmouse, &x_min, &y_min, &x_max, &y_max, &width))
                return -1;

        __set_bit(INPUT_PROP_POINTER, dev->propbit);
        __set_bit(EV_KEY, dev->evbit);

        __set_bit(EV_ABS, dev->evbit);
        __clear_bit(EV_REL, dev->evbit);

        __set_bit(BTN_LEFT, dev->keybit);
        __set_bit(BTN_RIGHT, dev->keybit);

        __set_bit(BTN_TOUCH, dev->keybit);
        __set_bit(BTN_TOOL_FINGER, dev->keybit);
        __set_bit(BTN_TOOL_DOUBLETAP, dev->keybit);
        __set_bit(BTN_TOOL_TRIPLETAP, dev->keybit);

        switch (etd->hw_version) {
        case 1:
                /* Rocker button */
                if (etd->fw_version < 0x020000 &&
                    (etd->capabilities[0] & ETP_CAP_HAS_ROCKER)) {
                        __set_bit(BTN_FORWARD, dev->keybit);
                        __set_bit(BTN_BACK, dev->keybit);
                }
                input_set_abs_params(dev, ABS_X, x_min, x_max, 0, 0);
                input_set_abs_params(dev, ABS_Y, y_min, y_max, 0, 0);
                break;

        case 2:
                __set_bit(BTN_TOOL_QUADTAP, dev->keybit);
                __set_bit(INPUT_PROP_SEMI_MT, dev->propbit);
                /* fall through */
        case 3:
                input_set_abs_params(dev, ABS_X, x_min, x_max, 0, 0);
                input_set_abs_params(dev, ABS_Y, y_min, y_max, 0, 0);
                if (etd->reports_pressure) {
                        input_set_abs_params(dev, ABS_PRESSURE, ETP_PMIN_V2,
                                             ETP_PMAX_V2, 0, 0);
                        input_set_abs_params(dev, ABS_TOOL_WIDTH, ETP_WMIN_V2,
                                             ETP_WMAX_V2, 0, 0);
                }
                input_mt_init_slots(dev, 2, 0);
                input_set_abs_params(dev, ABS_MT_POSITION_X, x_min, x_max, 0, 0);
                input_set_abs_params(dev, ABS_MT_POSITION_Y, y_min, y_max, 0, 0);
                break;

        case 4:
                if (elantech_get_resolution_v4(psmouse, &x_res, &y_res)) {
                        /*
                         * if query failed, print a warning and leave the values
                         * zero to resemble synaptics.c behavior.
                         */
                        psmouse_warn(psmouse, "couldn't query resolution data.\n");
                }
                /* v4 is clickpad, with only one button. */
                __set_bit(INPUT_PROP_BUTTONPAD, dev->propbit);
                __clear_bit(BTN_RIGHT, dev->keybit);
                __set_bit(BTN_TOOL_QUADTAP, dev->keybit);
                /* For X to recognize me as touchpad. */
                input_set_abs_params(dev, ABS_X, x_min, x_max, 0, 0);
                input_set_abs_params(dev, ABS_Y, y_min, y_max, 0, 0);
                input_abs_set_res(dev, ABS_X, x_res);
                input_abs_set_res(dev, ABS_Y, y_res);
                /*
                 * range of pressure and width is the same as v2,
                 * report ABS_PRESSURE, ABS_TOOL_WIDTH for compatibility.
                 */
                input_set_abs_params(dev, ABS_PRESSURE, ETP_PMIN_V2,
                                     ETP_PMAX_V2, 0, 0);
                input_set_abs_params(dev, ABS_TOOL_WIDTH, ETP_WMIN_V2,
                                     ETP_WMAX_V2, 0, 0);
                /* Multitouch capable pad, up to 5 fingers. */
                input_mt_init_slots(dev, ETP_MAX_FINGERS, 0);
                input_set_abs_params(dev, ABS_MT_POSITION_X, x_min, x_max, 0, 0);
                input_set_abs_params(dev, ABS_MT_POSITION_Y, y_min, y_max, 0, 0);
                input_abs_set_res(dev, ABS_MT_POSITION_X, x_res);
                input_abs_set_res(dev, ABS_MT_POSITION_Y, y_res);
                input_set_abs_params(dev, ABS_MT_PRESSURE, ETP_PMIN_V2,
                                     ETP_PMAX_V2, 0, 0);
                /*
                 * The firmware reports how many trace lines the finger spans,
                 * convert to surface unit as Protocol-B requires.
                 */
                input_set_abs_params(dev, ABS_MT_TOUCH_MAJOR, 0,
                                     ETP_WMAX_V2 * width, 0, 0);
                break;
        }

        etd->y_max = y_max;
        etd->width = width;

        return 0;
}

struct elantech_attr_data {
        size_t          field_offset;
        unsigned char   reg;
};

/*
 * Display a register value by reading a sysfs entry
 */
static ssize_t elantech_show_int_attr(struct psmouse *psmouse, void *data,
                                        char *buf)
{
        struct elantech_data *etd = psmouse->private;
        struct elantech_attr_data *attr = data;
        unsigned char *reg = (unsigned char *) etd + attr->field_offset;
        int rc = 0;

        if (attr->reg)
                rc = elantech_read_reg(psmouse, attr->reg, reg);

        return sprintf(buf, "0x%02x\n", (attr->reg && rc) ? -1 : *reg);
}

/*
 * Write a register value by writing a sysfs entry
 */
static ssize_t elantech_set_int_attr(struct psmouse *psmouse,
                                     void *data, const char *buf, size_t count)
{
        struct elantech_data *etd = psmouse->private;
        struct elantech_attr_data *attr = data;
        unsigned char *reg = (unsigned char *) etd + attr->field_offset;
        unsigned char value;
        int err;

        err = kstrtou8(buf, 16, &value);
        if (err)
                return err;

        /* Do we need to preserve some bits for version 2 hardware too? */
        if (etd->hw_version == 1) {
                if (attr->reg == 0x10)
                        /* Force absolute mode always on */
                        value |= ETP_R10_ABSOLUTE_MODE;
                else if (attr->reg == 0x11)
                        /* Force 4 byte mode always on */
                        value |= ETP_R11_4_BYTE_MODE;
        }

        if (!attr->reg || elantech_write_reg(psmouse, attr->reg, value) == 0)
                *reg = value;

        return count;
}

#define ELANTECH_INT_ATTR(_name, _register)                             \
        static struct elantech_attr_data elantech_attr_##_name = {      \
                .field_offset = offsetof(struct elantech_data, _name),  \
                .reg = _register,                                       \
        };                                                              \
        PSMOUSE_DEFINE_ATTR(_name, S_IWUSR | S_IRUGO,                   \
                            &elantech_attr_##_name,                     \
                            elantech_show_int_attr,                     \
                            elantech_set_int_attr)

ELANTECH_INT_ATTR(reg_07, 0x07);
ELANTECH_INT_ATTR(reg_10, 0x10);
ELANTECH_INT_ATTR(reg_11, 0x11);
ELANTECH_INT_ATTR(reg_20, 0x20);
ELANTECH_INT_ATTR(reg_21, 0x21);
ELANTECH_INT_ATTR(reg_22, 0x22);
ELANTECH_INT_ATTR(reg_23, 0x23);
ELANTECH_INT_ATTR(reg_24, 0x24);
ELANTECH_INT_ATTR(reg_25, 0x25);
ELANTECH_INT_ATTR(reg_26, 0x26);
ELANTECH_INT_ATTR(debug, 0);
ELANTECH_INT_ATTR(paritycheck, 0);

static struct attribute *elantech_attrs[] = {
        &psmouse_attr_reg_07.dattr.attr,
        &psmouse_attr_reg_10.dattr.attr,
        &psmouse_attr_reg_11.dattr.attr,
        &psmouse_attr_reg_20.dattr.attr,
        &psmouse_attr_reg_21.dattr.attr,
        &psmouse_attr_reg_22.dattr.attr,
        &psmouse_attr_reg_23.dattr.attr,
        &psmouse_attr_reg_24.dattr.attr,
        &psmouse_attr_reg_25.dattr.attr,
        &psmouse_attr_reg_26.dattr.attr,
        &psmouse_attr_debug.dattr.attr,
        &psmouse_attr_paritycheck.dattr.attr,
        NULL
};

static struct attribute_group elantech_attr_group = {
        .attrs = elantech_attrs,
};

static bool elantech_is_signature_valid(const unsigned char *param)
{
        static const unsigned char rates[] = { 200, 100, 80, 60, 40, 20, 10 };
        int i;

        if (param[0] == 0)
                return false;

        if (param[1] == 0)
                return true;

        for (i = 0; i < ARRAY_SIZE(rates); i++)
                if (param[2] == rates[i])
                        return false;

        return true;
}

/*
 * Use magic knock to detect Elantech touchpad
 */
int elantech_detect(struct psmouse *psmouse, bool set_properties)
{
        struct ps2dev *ps2dev = &psmouse->ps2dev;
        unsigned char param[3];

        ps2_command(&psmouse->ps2dev, NULL, PSMOUSE_CMD_RESET_DIS);

        if (ps2_command(ps2dev,  NULL, PSMOUSE_CMD_DISABLE) ||
            ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11) ||
            ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11) ||
            ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11) ||
            ps2_command(ps2dev, param, PSMOUSE_CMD_GETINFO)) {
                psmouse_dbg(psmouse, "sending Elantech magic knock failed.\n");
                return -1;
        }

        /*
         * Report this in case there are Elantech models that use a different
         * set of magic numbers
         */
        if (param[0] != 0x3c || param[1] != 0x03 ||
            (param[2] != 0xc8 && param[2] != 0x00)) {
                psmouse_dbg(psmouse,
                            "unexpected magic knock result 0x%02x, 0x%02x, 0x%02x.\n",
                            param[0], param[1], param[2]);
                return -1;
        }

        /*
         * Query touchpad's firmware version and see if it reports known
         * value to avoid mis-detection. Logitech mice are known to respond
         * to Elantech magic knock and there might be more.
         */
        if (synaptics_send_cmd(psmouse, ETP_FW_VERSION_QUERY, param)) {
                psmouse_dbg(psmouse, "failed to query firmware version.\n");
                return -1;
        }

        psmouse_dbg(psmouse,
                    "Elantech version query result 0x%02x, 0x%02x, 0x%02x.\n",
                    param[0], param[1], param[2]);

        if (!elantech_is_signature_valid(param)) {
                psmouse_dbg(psmouse,
                            "Probably not a real Elantech touchpad. Aborting.\n");
                return -1;
        }

        if (set_properties) {
                psmouse->vendor = "Elantech";
                psmouse->name = "Touchpad";
        }

        return 0;
}

/*
 * Clean up sysfs entries when disconnecting
 */
static void elantech_disconnect(struct psmouse *psmouse)
{
        sysfs_remove_group(&psmouse->ps2dev.serio->dev.kobj,
                           &elantech_attr_group);
        kfree(psmouse->private);
        psmouse->private = NULL;
}

/*
 * Put the touchpad back into absolute mode when reconnecting
 */
static int elantech_reconnect(struct psmouse *psmouse)
{
        psmouse_reset(psmouse);

        if (elantech_detect(psmouse, 0))
                return -1;

        if (elantech_set_absolute_mode(psmouse)) {
                psmouse_err(psmouse,
                            "failed to put touchpad back into absolute mode.\n");
                return -1;
        }

        return 0;
}

/*
 * determine hardware version and set some properties according to it.
 */
static int elantech_set_properties(struct elantech_data *etd)
{
        /* This represents the version of IC body. */
        int ver = (etd->fw_version & 0x0f0000) >> 16;

        /* Early version of Elan touchpads doesn't obey the rule. */
        if (etd->fw_version < 0x020030 || etd->fw_version == 0x020600)
                etd->hw_version = 1;
        else {
                switch (ver) {
                case 2:
                case 4:
                        etd->hw_version = 2;
                        break;
                case 5:
                        etd->hw_version = 3;
                        break;
                case 6:
                case 7:
                        etd->hw_version = 4;
                        break;
                default:
                        return -1;
                }
        }

        /* decide which send_cmd we're gonna use early */
        etd->send_cmd = etd->hw_version >= 3 ? elantech_send_cmd :
                                               synaptics_send_cmd;

        /* Turn on packet checking by default */
        etd->paritycheck = 1;

        /*
         * This firmware suffers from misreporting coordinates when
         * a touch action starts causing the mouse cursor or scrolled page
         * to jump. Enable a workaround.
         */
        etd->jumpy_cursor =
                (etd->fw_version == 0x020022 || etd->fw_version == 0x020600);

        if (etd->hw_version > 1) {
                /* For now show extra debug information */
                etd->debug = 1;

                if (etd->fw_version >= 0x020800)
                        etd->reports_pressure = true;
        }

        /*
         * The signatures of v3 and v4 packets change depending on the
         * value of this hardware flag.
         */
        etd->crc_enabled = ((etd->fw_version & 0x4000) == 0x4000);

        return 0;
}

/*
 * Initialize the touchpad and create sysfs entries
 */
int elantech_init(struct psmouse *psmouse)
{
        struct elantech_data *etd;
        int i, error;
        unsigned char param[3];

        psmouse->private = etd = kzalloc(sizeof(struct elantech_data), GFP_KERNEL);
        if (!etd)
                return -ENOMEM;

        psmouse_reset(psmouse);

        etd->parity[0] = 1;
        for (i = 1; i < 256; i++)
                etd->parity[i] = etd->parity[i & (i - 1)] ^ 1;

        /*
         * Do the version query again so we can store the result
         */
        if (synaptics_send_cmd(psmouse, ETP_FW_VERSION_QUERY, param)) {
                psmouse_err(psmouse, "failed to query firmware version.\n");
                goto init_fail;
        }
        etd->fw_version = (param[0] << 16) | (param[1] << 8) | param[2];

        if (elantech_set_properties(etd)) {
                psmouse_err(psmouse, "unknown hardware version, aborting...\n");
                goto init_fail;
        }
        psmouse_info(psmouse,
                     "assuming hardware version %d (with firmware version 0x%02x%02x%02x)\n",
                     etd->hw_version, param[0], param[1], param[2]);

        if (etd->send_cmd(psmouse, ETP_CAPABILITIES_QUERY,
            etd->capabilities)) {
                psmouse_err(psmouse, "failed to query capabilities.\n");
                goto init_fail;
        }
        psmouse_info(psmouse,
                     "Synaptics capabilities query result 0x%02x, 0x%02x, 0x%02x.\n",
                     etd->capabilities[0], etd->capabilities[1],
                     etd->capabilities[2]);

        if (elantech_set_absolute_mode(psmouse)) {
                psmouse_err(psmouse,
                            "failed to put touchpad into absolute mode.\n");
                goto init_fail;
        }

        if (elantech_set_input_params(psmouse)) {
                psmouse_err(psmouse, "failed to query touchpad range.\n");
                goto init_fail;
        }

        error = sysfs_create_group(&psmouse->ps2dev.serio->dev.kobj,
                                   &elantech_attr_group);
        if (error) {
                psmouse_err(psmouse,
                            "failed to create sysfs attributes, error: %d.\n",
                            error);
                goto init_fail;
        }

        psmouse->protocol_handler = elantech_process_byte;
        psmouse->disconnect = elantech_disconnect;
        psmouse->reconnect = elantech_reconnect;
        psmouse->pktsize = etd->hw_version > 1 ? 6 : 4;

        return 0;

 init_fail:
        kfree(etd);
        return -1;
}