/*
 * 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_report_key(dev, BTN_RIGHT, packet[0] & 0x02);
	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;
}

/*
 * Advertise INPUT_PROP_BUTTONPAD for clickpads. The testing of bit 12 in
 * fw_version for this is based on the following fw_version & caps table:
 *
 * Laptop-model:           fw_version:     caps:           buttons:
 * Acer S3                 0x461f00        10, 13, 0e      clickpad
 * Acer S7-392             0x581f01        50, 17, 0d      clickpad
 * Acer V5-131             0x461f02        01, 16, 0c      clickpad
 * Acer V5-551             0x461f00        ?               clickpad
 * Asus K53SV              0x450f01        78, 15, 0c      2 hw buttons
 * Asus G46VW              0x460f02        00, 18, 0c      2 hw buttons
 * Asus G750JX             0x360f00        00, 16, 0c      2 hw buttons
 * Asus UX31               0x361f00        20, 15, 0e      clickpad
 * Asus UX32VD             0x361f02        00, 15, 0e      clickpad
 * Avatar AVIU-145A2       0x361f00        ?               clickpad
 * Gigabyte U2442          0x450f01        58, 17, 0c      2 hw buttons
 * Lenovo L430             0x350f02        b9, 15, 0c      2 hw buttons (*)
 * Samsung NF210           0x150b00        78, 14, 0a      2 hw buttons
 * Samsung NP770Z5E        0x575f01        10, 15, 0f      clickpad
 * Samsung NP700Z5B        0x361f06        21, 15, 0f      clickpad
 * Samsung NP900X3E-A02    0x575f03        ?               clickpad
 * Samsung NP-QX410        0x851b00        19, 14, 0c      clickpad
 * Samsung RC512           0x450f00        08, 15, 0c      2 hw buttons
 * Samsung RF710           0x450f00        ?               2 hw buttons
 * System76 Pangolin       0x250f01        ?               2 hw buttons
 * (*) + 3 trackpoint buttons
 */
static void elantech_set_buttonpad_prop(struct psmouse *psmouse)
{
	struct input_dev *dev = psmouse->dev;
	struct elantech_data *etd = psmouse->private;

	if (etd->fw_version & 0x001000) {
		__set_bit(INPUT_PROP_BUTTONPAD, dev->propbit);
		__clear_bit(BTN_RIGHT, dev->keybit);
	}
}

/*
 * 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:
		if (etd->hw_version == 3)
			elantech_set_buttonpad_prop(psmouse);
		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");
		}
		elantech_set_buttonpad_prop(psmouse);
		__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:
		case 8:
			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;
}