/*
 * Elantech Touchpad driver (v5)
 *
 * Copyright (C) 2007-2008 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/module.h>
#include <linux/input.h>
#include <linux/serio.h>
#include <linux/libps2.h>
#include "psmouse.h"
#include "elantech.h"

#define elantech_debug(format, arg...)                          \
        do {                                                    \
                if (etd->debug)                                 \
                        printk(KERN_DEBUG format, ##arg);       \
        } 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)) {
                pr_err("elantech.c: synaptics_send_cmd query 0x%02x failed.\n", 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("elantech.c: retrying ps2 command 0x%02x (%d).\n",
                        command, tries);
                msleep(ETP_PS2_COMMAND_DELAY);
        } while (tries > 0);

        if (rc)
                pr_err("elantech.c: 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 < 0x10 || 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;
        }

        if (rc)
                pr_err("elantech.c: failed to read register 0x%02x.\n", reg);
        else
                *val = param[0];

        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 < 0x10 || 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;
        }

        if (rc)
                pr_err("elantech.c: 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(unsigned char *packet, int size)
{
        int     i;

        printk(KERN_DEBUG "elantech.c: PS/2 packet [");
        for (i = 0; i < size; i++)
                printk("%s0x%02x ", (i) ? ", " : " ", 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_maj == 0x01) {
                /* 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;
        }

        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, ETP_YMAX_V1 -
                        (((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_maj == 0x01) &&
            (etd->capabilities & 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);
}

/*
 * 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 input_dev *dev = psmouse->dev;
        unsigned char *packet = psmouse->packet;
        int fingers, x1, y1, x2, y2;

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

        switch (fingers) {
        case 1:
                /* byte 1: x15 x14 x13 x12 x11 x10 x9  x8
                   byte 2: x7  x6  x5  x4  x4  x2  x1  x0 */
                input_report_abs(dev, ABS_X, (packet[1] << 8) | packet[2]);
                /* byte 4: y15 y14 y13 y12 y11 y10 y8  y8
                   byte 5: y7  y6  y5  y4  y3  y2  y1  y0 */
                input_report_abs(dev, ABS_Y, ETP_YMAX_V2 -
                        ((packet[4] << 8) | packet[5]));
                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];
                /* byte 2: ay7 ay6 ay5 ay4 ay3 ay2 ay1 ay0 */
                y1 = ETP_2FT_YMAX - (((packet[0] & 0x20) << 3) | packet[2]);
                /* byte 3:  .   .  by8 bx8  .   .   .   .
                   byte 4: bx7 bx6 bx5 bx4 bx3 bx2 bx1 bx0 */
                x2 = ((packet[3] & 0x10) << 4) | packet[4];
                /* byte 5: by7 by8 by5 by4 by3 by2 by1 by0 */
                y2 = ETP_2FT_YMAX - (((packet[3] & 0x20) << 3) | packet[5]);
                /* For compatibility with the X Synaptics driver scale up one
                   coordinate and report as ordinary mouse movent */
                input_report_abs(dev, ABS_X, x1 << 2);
                input_report_abs(dev, ABS_Y, y1 << 2);
                /* For compatibility with the proprietary X Elantech driver
                   report both coordinates as hat coordinates */
                input_report_abs(dev, ABS_HAT0X, x1);
                input_report_abs(dev, ABS_HAT0Y, y1);
                input_report_abs(dev, ABS_HAT1X, x2);
                input_report_abs(dev, ABS_HAT1Y, y2);
                break;
        }

        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_sync(dev);
}

static int elantech_check_parity_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_maj == 0x01) {
                /* 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;
}

/*
 * 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;

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

        if (etd->debug > 1)
                elantech_packet_dump(psmouse->packet, psmouse->pktsize);

        switch (etd->hw_version) {
        case 1:
                if (etd->paritycheck && !elantech_check_parity_v1(psmouse))
                        return PSMOUSE_BAD_DATA;

                elantech_report_absolute_v1(psmouse);
                break;

        case 2:
                /* We don't know how to check parity in protocol v2 */
                elantech_report_absolute_v2(psmouse);
                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;
                }
                /*
                 * Read back reg 0x10. The touchpad is probably initalising
                 * 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("elantech.c: retrying read (%d).\n",
                                tries);
                        msleep(ETP_READ_BACK_DELAY);
                } while (tries > 0);
                if (rc)
                        pr_err("elantech.c: failed to read back register 0x10.\n");
                break;
        }

        if (rc)
                pr_err("elantech.c: failed to initialise registers.\n");

        return rc;
}

/*
 * Set the appropriate event bits for the input subsystem
 */
static void elantech_set_input_params(struct psmouse *psmouse)
{
        struct input_dev *dev = psmouse->dev;
        struct elantech_data *etd = psmouse->private;

        __set_bit(EV_KEY, dev->evbit);
        __set_bit(EV_ABS, 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_maj == 0x01) &&
                    (etd->capabilities & ETP_CAP_HAS_ROCKER)) {
                        __set_bit(BTN_FORWARD, dev->keybit);
                        __set_bit(BTN_BACK, dev->keybit);
                }
                input_set_abs_params(dev, ABS_X, ETP_XMIN_V1, ETP_XMAX_V1, 0, 0);
                input_set_abs_params(dev, ABS_Y, ETP_YMIN_V1, ETP_YMAX_V1, 0, 0);
                break;

        case 2:
                input_set_abs_params(dev, ABS_X, ETP_XMIN_V2, ETP_XMAX_V2, 0, 0);
                input_set_abs_params(dev, ABS_Y, ETP_YMIN_V2, ETP_YMAX_V2, 0, 0);
                input_set_abs_params(dev, ABS_HAT0X, ETP_2FT_XMIN, ETP_2FT_XMAX, 0, 0);
                input_set_abs_params(dev, ABS_HAT0Y, ETP_2FT_YMIN, ETP_2FT_YMAX, 0, 0);
                input_set_abs_params(dev, ABS_HAT1X, ETP_2FT_XMIN, ETP_2FT_XMAX, 0, 0);
                input_set_abs_params(dev, ABS_HAT1Y, ETP_2FT_YMIN, ETP_2FT_YMAX, 0, 0);
                break;
        }
}

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 long value;
        int err;

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

        if (value > 0xff)
                return -EINVAL;

        /* 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_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_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,
};

/*
 * Use magic knock to detect Elantech touchpad
 */
int elantech_detect(struct psmouse *psmouse, int 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)) {
                pr_err("elantech.c: 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) {
                pr_info("elantech.c: unexpected magic knock result 0x%02x, 0x%02x, 0x%02x.\n",
                        param[0], param[1], param[2]);
                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)
{
        if (elantech_detect(psmouse, 0))
                return -1;

        if (elantech_set_absolute_mode(psmouse)) {
                pr_err("elantech.c: failed to put touchpad back into absolute mode.\n");
                return -1;
        }

        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];

        etd = kzalloc(sizeof(struct elantech_data), GFP_KERNEL);
        psmouse->private = etd;
        if (!etd)
                return -1;

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

        /*
         * Find out what version hardware this is
         */
        if (synaptics_send_cmd(psmouse, ETP_FW_VERSION_QUERY, param)) {
                pr_err("elantech.c: failed to query firmware version.\n");
                goto init_fail;
        }
        pr_info("elantech.c: Elantech version query result 0x%02x, 0x%02x, 0x%02x.\n",
                param[0], param[1], param[2]);
        etd->fw_version_maj = param[0];
        etd->fw_version_min = param[2];

        /*
         * Assume every version greater than this is new EeePC style
         * hardware with 6 byte packets
         */
        if (etd->fw_version_maj >= 0x02 && etd->fw_version_min >= 0x30) {
                etd->hw_version = 2;
                /* For now show extra debug information */
                etd->debug = 1;
                /* Don't know how to do parity checking for version 2 */
                etd->paritycheck = 0;
        } else {
                etd->hw_version = 1;
                etd->paritycheck = 1;
        }
        pr_info("elantech.c: assuming hardware version %d, firmware version %d.%d\n",
                etd->hw_version, etd->fw_version_maj, etd->fw_version_min);

        if (synaptics_send_cmd(psmouse, ETP_CAPABILITIES_QUERY, param)) {
                pr_err("elantech.c: failed to query capabilities.\n");
                goto init_fail;
        }
        pr_info("elantech.c: Synaptics capabilities query result 0x%02x, 0x%02x, 0x%02x.\n",
                param[0], param[1], param[2]);
        etd->capabilities = param[0];

        if (elantech_set_absolute_mode(psmouse)) {
                pr_err("elantech.c: failed to put touchpad into absolute mode.\n");
                goto init_fail;
        }

        elantech_set_input_params(psmouse);

        error = sysfs_create_group(&psmouse->ps2dev.serio->dev.kobj,
                                   &elantech_attr_group);
        if (error) {
                pr_err("elantech.c: 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 == 2 ? 6 : 4;

        return 0;

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