/*
 * Copyright (C) 2012-2013 MundoReader S.L.
 * Author: Heiko Stuebner <heiko@sntech.de>
 *
 * based in parts on Nook zforce driver
 *
 * Copyright (C) 2010 Barnes & Noble, Inc.
 * Author: Pieter Truter<ptruter@intrinsyc.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/hrtimer.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/device.h>
#include <linux/sysfs.h>
#include <linux/input/mt.h>
#include <linux/platform_data/zforce_ts.h>
#include <linux/regulator/consumer.h>
#include <linux/of.h>

#define WAIT_TIMEOUT            msecs_to_jiffies(1000)

#define FRAME_START             0xee
#define FRAME_MAXSIZE           257

/* Offsets of the different parts of the payload the controller sends */
#define PAYLOAD_HEADER          0
#define PAYLOAD_LENGTH          1
#define PAYLOAD_BODY            2

/* Response offsets */
#define RESPONSE_ID             0
#define RESPONSE_DATA           1

/* Commands */
#define COMMAND_DEACTIVATE      0x00
#define COMMAND_INITIALIZE      0x01
#define COMMAND_RESOLUTION      0x02
#define COMMAND_SETCONFIG       0x03
#define COMMAND_DATAREQUEST     0x04
#define COMMAND_SCANFREQ        0x08
#define COMMAND_STATUS          0X1e

/*
 * Responses the controller sends as a result of
 * command requests
 */
#define RESPONSE_DEACTIVATE     0x00
#define RESPONSE_INITIALIZE     0x01
#define RESPONSE_RESOLUTION     0x02
#define RESPONSE_SETCONFIG      0x03
#define RESPONSE_SCANFREQ       0x08
#define RESPONSE_STATUS         0X1e

/*
 * Notifications are sent by the touch controller without
 * being requested by the driver and include for example
 * touch indications
 */
#define NOTIFICATION_TOUCH              0x04
#define NOTIFICATION_BOOTCOMPLETE       0x07
#define NOTIFICATION_OVERRUN            0x25
#define NOTIFICATION_PROXIMITY          0x26
#define NOTIFICATION_INVALID_COMMAND    0xfe

#define ZFORCE_REPORT_POINTS            2
#define ZFORCE_MAX_AREA                 0xff

#define STATE_DOWN                      0
#define STATE_MOVE                      1
#define STATE_UP                        2

#define SETCONFIG_DUALTOUCH             (1 << 0)

struct zforce_point {
        int coord_x;
        int coord_y;
        int state;
        int id;
        int area_major;
        int area_minor;
        int orientation;
        int pressure;
        int prblty;
};

/*
 * @client              the i2c_client
 * @input               the input device
 * @suspending          in the process of going to suspend (don't emit wakeup
 *                      events for commands executed to suspend the device)
 * @suspended           device suspended
 * @access_mutex        serialize i2c-access, to keep multipart reads together
 * @command_done        completion to wait for the command result
 * @command_mutex       serialize commands sent to the ic
 * @command_waiting     the id of the command that is currently waiting
 *                      for a result
 * @command_result      returned result of the command
 */
struct zforce_ts {
        struct i2c_client       *client;
        struct input_dev        *input;
        const struct zforce_ts_platdata *pdata;
        char                    phys[32];

        struct regulator        *reg_vdd;

        struct gpio_desc        *gpio_int;
        struct gpio_desc        *gpio_rst;

        bool                    suspending;
        bool                    suspended;
        bool                    boot_complete;

        /* Firmware version information */
        u16                     version_major;
        u16                     version_minor;
        u16                     version_build;
        u16                     version_rev;

        struct mutex            access_mutex;

        struct completion       command_done;
        struct mutex            command_mutex;
        int                     command_waiting;
        int                     command_result;
};

static int zforce_command(struct zforce_ts *ts, u8 cmd)
{
        struct i2c_client *client = ts->client;
        char buf[3];
        int ret;

        dev_dbg(&client->dev, "%s: 0x%x\n", __func__, cmd);

        buf[0] = FRAME_START;
        buf[1] = 1; /* data size, command only */
        buf[2] = cmd;

        mutex_lock(&ts->access_mutex);
        ret = i2c_master_send(client, &buf[0], ARRAY_SIZE(buf));
        mutex_unlock(&ts->access_mutex);
        if (ret < 0) {
                dev_err(&client->dev, "i2c send data request error: %d\n", ret);
                return ret;
        }

        return 0;
}

static void zforce_reset_assert(struct zforce_ts *ts)
{
        gpiod_set_value_cansleep(ts->gpio_rst, 1);
}

static void zforce_reset_deassert(struct zforce_ts *ts)
{
        gpiod_set_value_cansleep(ts->gpio_rst, 0);
}

static int zforce_send_wait(struct zforce_ts *ts, const char *buf, int len)
{
        struct i2c_client *client = ts->client;
        int ret;

        ret = mutex_trylock(&ts->command_mutex);
        if (!ret) {
                dev_err(&client->dev, "already waiting for a command\n");
                return -EBUSY;
        }

        dev_dbg(&client->dev, "sending %d bytes for command 0x%x\n",
                buf[1], buf[2]);

        ts->command_waiting = buf[2];

        mutex_lock(&ts->access_mutex);
        ret = i2c_master_send(client, buf, len);
        mutex_unlock(&ts->access_mutex);
        if (ret < 0) {
                dev_err(&client->dev, "i2c send data request error: %d\n", ret);
                goto unlock;
        }

        dev_dbg(&client->dev, "waiting for result for command 0x%x\n", buf[2]);

        if (wait_for_completion_timeout(&ts->command_done, WAIT_TIMEOUT) == 0) {
                ret = -ETIME;
                goto unlock;
        }

        ret = ts->command_result;

unlock:
        mutex_unlock(&ts->command_mutex);
        return ret;
}

static int zforce_command_wait(struct zforce_ts *ts, u8 cmd)
{
        struct i2c_client *client = ts->client;
        char buf[3];
        int ret;

        dev_dbg(&client->dev, "%s: 0x%x\n", __func__, cmd);

        buf[0] = FRAME_START;
        buf[1] = 1; /* data size, command only */
        buf[2] = cmd;

        ret = zforce_send_wait(ts, &buf[0], ARRAY_SIZE(buf));
        if (ret < 0) {
                dev_err(&client->dev, "i2c send data request error: %d\n", ret);
                return ret;
        }

        return 0;
}

static int zforce_resolution(struct zforce_ts *ts, u16 x, u16 y)
{
        struct i2c_client *client = ts->client;
        char buf[7] = { FRAME_START, 5, COMMAND_RESOLUTION,
                        (x & 0xff), ((x >> 8) & 0xff),
                        (y & 0xff), ((y >> 8) & 0xff) };

        dev_dbg(&client->dev, "set resolution to (%d,%d)\n", x, y);

        return zforce_send_wait(ts, &buf[0], ARRAY_SIZE(buf));
}

static int zforce_scan_frequency(struct zforce_ts *ts, u16 idle, u16 finger,
                                 u16 stylus)
{
        struct i2c_client *client = ts->client;
        char buf[9] = { FRAME_START, 7, COMMAND_SCANFREQ,
                        (idle & 0xff), ((idle >> 8) & 0xff),
                        (finger & 0xff), ((finger >> 8) & 0xff),
                        (stylus & 0xff), ((stylus >> 8) & 0xff) };

        dev_dbg(&client->dev,
                "set scan frequency to (idle: %d, finger: %d, stylus: %d)\n",
                idle, finger, stylus);

        return zforce_send_wait(ts, &buf[0], ARRAY_SIZE(buf));
}

static int zforce_setconfig(struct zforce_ts *ts, char b1)
{
        struct i2c_client *client = ts->client;
        char buf[7] = { FRAME_START, 5, COMMAND_SETCONFIG,
                        b1, 0, 0, 0 };

        dev_dbg(&client->dev, "set config to (%d)\n", b1);

        return zforce_send_wait(ts, &buf[0], ARRAY_SIZE(buf));
}

static int zforce_start(struct zforce_ts *ts)
{
        struct i2c_client *client = ts->client;
        const struct zforce_ts_platdata *pdata = ts->pdata;
        int ret;

        dev_dbg(&client->dev, "starting device\n");

        ret = zforce_command_wait(ts, COMMAND_INITIALIZE);
        if (ret) {
                dev_err(&client->dev, "Unable to initialize, %d\n", ret);
                return ret;
        }

        ret = zforce_resolution(ts, pdata->x_max, pdata->y_max);
        if (ret) {
                dev_err(&client->dev, "Unable to set resolution, %d\n", ret);
                goto error;
        }

        ret = zforce_scan_frequency(ts, 10, 50, 50);
        if (ret) {
                dev_err(&client->dev, "Unable to set scan frequency, %d\n",
                        ret);
                goto error;
        }

        ret = zforce_setconfig(ts, SETCONFIG_DUALTOUCH);
        if (ret) {
                dev_err(&client->dev, "Unable to set config\n");
                goto error;
        }

        /* start sending touch events */
        ret = zforce_command(ts, COMMAND_DATAREQUEST);
        if (ret) {
                dev_err(&client->dev, "Unable to request data\n");
                goto error;
        }

        /*
         * Per NN, initial cal. take max. of 200msec.
         * Allow time to complete this calibration
         */
        msleep(200);

        return 0;

error:
        zforce_command_wait(ts, COMMAND_DEACTIVATE);
        return ret;
}

static int zforce_stop(struct zforce_ts *ts)
{
        struct i2c_client *client = ts->client;
        int ret;

        dev_dbg(&client->dev, "stopping device\n");

        /* Deactivates touch sensing and puts the device into sleep. */
        ret = zforce_command_wait(ts, COMMAND_DEACTIVATE);
        if (ret != 0) {
                dev_err(&client->dev, "could not deactivate device, %d\n",
                        ret);
                return ret;
        }

        return 0;
}

static int zforce_touch_event(struct zforce_ts *ts, u8 *payload)
{
        struct i2c_client *client = ts->client;
        const struct zforce_ts_platdata *pdata = ts->pdata;
        struct zforce_point point;
        int count, i, num = 0;

        count = payload[0];
        if (count > ZFORCE_REPORT_POINTS) {
                dev_warn(&client->dev,
                         "too many coordinates %d, expected max %d\n",
                         count, ZFORCE_REPORT_POINTS);
                count = ZFORCE_REPORT_POINTS;
        }

        for (i = 0; i < count; i++) {
                point.coord_x =
                        payload[9 * i + 2] << 8 | payload[9 * i + 1];
                point.coord_y =
                        payload[9 * i + 4] << 8 | payload[9 * i + 3];

                if (point.coord_x > pdata->x_max ||
                    point.coord_y > pdata->y_max) {
                        dev_warn(&client->dev, "coordinates (%d,%d) invalid\n",
                                point.coord_x, point.coord_y);
                        point.coord_x = point.coord_y = 0;
                }

                point.state = payload[9 * i + 5] & 0x0f;
                point.id = (payload[9 * i + 5] & 0xf0) >> 4;

                /* determine touch major, minor and orientation */
                point.area_major = max(payload[9 * i + 6],
                                          payload[9 * i + 7]);
                point.area_minor = min(payload[9 * i + 6],
                                          payload[9 * i + 7]);
                point.orientation = payload[9 * i + 6] > payload[9 * i + 7];

                point.pressure = payload[9 * i + 8];
                point.prblty = payload[9 * i + 9];

                dev_dbg(&client->dev,
                        "point %d/%d: state %d, id %d, pressure %d, prblty %d, x %d, y %d, amajor %d, aminor %d, ori %d\n",
                        i, count, point.state, point.id,
                        point.pressure, point.prblty,
                        point.coord_x, point.coord_y,
                        point.area_major, point.area_minor,
                        point.orientation);

                /* the zforce id starts with "1", so needs to be decreased */
                input_mt_slot(ts->input, point.id - 1);

                input_mt_report_slot_state(ts->input, MT_TOOL_FINGER,
                                                point.state != STATE_UP);

                if (point.state != STATE_UP) {
                        input_report_abs(ts->input, ABS_MT_POSITION_X,
                                         point.coord_x);
                        input_report_abs(ts->input, ABS_MT_POSITION_Y,
                                         point.coord_y);
                        input_report_abs(ts->input, ABS_MT_TOUCH_MAJOR,
                                         point.area_major);
                        input_report_abs(ts->input, ABS_MT_TOUCH_MINOR,
                                         point.area_minor);
                        input_report_abs(ts->input, ABS_MT_ORIENTATION,
                                         point.orientation);
                        num++;
                }
        }

        input_mt_sync_frame(ts->input);

        input_mt_report_finger_count(ts->input, num);

        input_sync(ts->input);

        return 0;
}

static int zforce_read_packet(struct zforce_ts *ts, u8 *buf)
{
        struct i2c_client *client = ts->client;
        int ret;

        mutex_lock(&ts->access_mutex);

        /* read 2 byte message header */
        ret = i2c_master_recv(client, buf, 2);
        if (ret < 0) {
                dev_err(&client->dev, "error reading header: %d\n", ret);
                goto unlock;
        }

        if (buf[PAYLOAD_HEADER] != FRAME_START) {
                dev_err(&client->dev, "invalid frame start: %d\n", buf[0]);
                ret = -EIO;
                goto unlock;
        }

        if (buf[PAYLOAD_LENGTH] == 0) {
                dev_err(&client->dev, "invalid payload length: %d\n",
                        buf[PAYLOAD_LENGTH]);
                ret = -EIO;
                goto unlock;
        }

        /* read the message */
        ret = i2c_master_recv(client, &buf[PAYLOAD_BODY], buf[PAYLOAD_LENGTH]);
        if (ret < 0) {
                dev_err(&client->dev, "error reading payload: %d\n", ret);
                goto unlock;
        }

        dev_dbg(&client->dev, "read %d bytes for response command 0x%x\n",
                buf[PAYLOAD_LENGTH], buf[PAYLOAD_BODY]);

unlock:
        mutex_unlock(&ts->access_mutex);
        return ret;
}

static void zforce_complete(struct zforce_ts *ts, int cmd, int result)
{
        struct i2c_client *client = ts->client;

        if (ts->command_waiting == cmd) {
                dev_dbg(&client->dev, "completing command 0x%x\n", cmd);
                ts->command_result = result;
                complete(&ts->command_done);
        } else {
                dev_dbg(&client->dev, "command %d not for us\n", cmd);
        }
}

static irqreturn_t zforce_irq(int irq, void *dev_id)
{
        struct zforce_ts *ts = dev_id;
        struct i2c_client *client = ts->client;

        if (ts->suspended && device_may_wakeup(&client->dev))
                pm_wakeup_event(&client->dev, 500);

        return IRQ_WAKE_THREAD;
}

static irqreturn_t zforce_irq_thread(int irq, void *dev_id)
{
        struct zforce_ts *ts = dev_id;
        struct i2c_client *client = ts->client;
        int ret;
        u8 payload_buffer[FRAME_MAXSIZE];
        u8 *payload;

        /*
         * When still suspended, return.
         * Due to the level-interrupt we will get re-triggered later.
         */
        if (ts->suspended) {
                msleep(20);
                return IRQ_HANDLED;
        }

        dev_dbg(&client->dev, "handling interrupt\n");

        /* Don't emit wakeup events from commands run by zforce_suspend */
        if (!ts->suspending && device_may_wakeup(&client->dev))
                pm_stay_awake(&client->dev);

        /*
         * Run at least once and exit the loop if
         * - the optional interrupt GPIO isn't specified
         *   (there is only one packet read per ISR invocation, then)
         * or
         * - the GPIO isn't active any more
         *   (packet read until the level GPIO indicates that there is
         *    no IRQ any more)
         */
        do {
                ret = zforce_read_packet(ts, payload_buffer);
                if (ret < 0) {
                        dev_err(&client->dev,
                                "could not read packet, ret: %d\n", ret);
                        break;
                }

                payload =  &payload_buffer[PAYLOAD_BODY];

                switch (payload[RESPONSE_ID]) {
                case NOTIFICATION_TOUCH:
                        /*
                         * Always report touch-events received while
                         * suspending, when being a wakeup source
                         */
                        if (ts->suspending && device_may_wakeup(&client->dev))
                                pm_wakeup_event(&client->dev, 500);
                        zforce_touch_event(ts, &payload[RESPONSE_DATA]);
                        break;

                case NOTIFICATION_BOOTCOMPLETE:
                        ts->boot_complete = payload[RESPONSE_DATA];
                        zforce_complete(ts, payload[RESPONSE_ID], 0);
                        break;

                case RESPONSE_INITIALIZE:
                case RESPONSE_DEACTIVATE:
                case RESPONSE_SETCONFIG:
                case RESPONSE_RESOLUTION:
                case RESPONSE_SCANFREQ:
                        zforce_complete(ts, payload[RESPONSE_ID],
                                        payload[RESPONSE_DATA]);
                        break;

                case RESPONSE_STATUS:
                        /*
                         * Version Payload Results
                         * [2:major] [2:minor] [2:build] [2:rev]
                         */
                        ts->version_major = (payload[RESPONSE_DATA + 1] << 8) |
                                                payload[RESPONSE_DATA];
                        ts->version_minor = (payload[RESPONSE_DATA + 3] << 8) |
                                                payload[RESPONSE_DATA + 2];
                        ts->version_build = (payload[RESPONSE_DATA + 5] << 8) |
                                                payload[RESPONSE_DATA + 4];
                        ts->version_rev   = (payload[RESPONSE_DATA + 7] << 8) |
                                                payload[RESPONSE_DATA + 6];
                        dev_dbg(&ts->client->dev,
                                "Firmware Version %04x:%04x %04x:%04x\n",
                                ts->version_major, ts->version_minor,
                                ts->version_build, ts->version_rev);

                        zforce_complete(ts, payload[RESPONSE_ID], 0);
                        break;

                case NOTIFICATION_INVALID_COMMAND:
                        dev_err(&ts->client->dev, "invalid command: 0x%x\n",
                                payload[RESPONSE_DATA]);
                        break;

                default:
                        dev_err(&ts->client->dev,
                                "unrecognized response id: 0x%x\n",
                                payload[RESPONSE_ID]);
                        break;
                }
        } while (gpiod_get_value_cansleep(ts->gpio_int));

        if (!ts->suspending && device_may_wakeup(&client->dev))
                pm_relax(&client->dev);

        dev_dbg(&client->dev, "finished interrupt\n");

        return IRQ_HANDLED;
}

static int zforce_input_open(struct input_dev *dev)
{
        struct zforce_ts *ts = input_get_drvdata(dev);

        return zforce_start(ts);
}

static void zforce_input_close(struct input_dev *dev)
{
        struct zforce_ts *ts = input_get_drvdata(dev);
        struct i2c_client *client = ts->client;
        int ret;

        ret = zforce_stop(ts);
        if (ret)
                dev_warn(&client->dev, "stopping zforce failed\n");

        return;
}

static int __maybe_unused zforce_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct zforce_ts *ts = i2c_get_clientdata(client);
        struct input_dev *input = ts->input;
        int ret = 0;

        mutex_lock(&input->mutex);
        ts->suspending = true;

        /*
         * When configured as a wakeup source device should always wake
         * the system, therefore start device if necessary.
         */
        if (device_may_wakeup(&client->dev)) {
                dev_dbg(&client->dev, "suspend while being a wakeup source\n");

                /* Need to start device, if not open, to be a wakeup source. */
                if (!input->users) {
                        ret = zforce_start(ts);
                        if (ret)
                                goto unlock;
                }

                enable_irq_wake(client->irq);
        } else if (input->users) {
                dev_dbg(&client->dev,
                        "suspend without being a wakeup source\n");

                ret = zforce_stop(ts);
                if (ret)
                        goto unlock;

                disable_irq(client->irq);
        }

        ts->suspended = true;

unlock:
        ts->suspending = false;
        mutex_unlock(&input->mutex);

        return ret;
}

static int __maybe_unused zforce_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct zforce_ts *ts = i2c_get_clientdata(client);
        struct input_dev *input = ts->input;
        int ret = 0;

        mutex_lock(&input->mutex);

        ts->suspended = false;

        if (device_may_wakeup(&client->dev)) {
                dev_dbg(&client->dev, "resume from being a wakeup source\n");

                disable_irq_wake(client->irq);

                /* need to stop device if it was not open on suspend */
                if (!input->users) {
                        ret = zforce_stop(ts);
                        if (ret)
                                goto unlock;
                }
        } else if (input->users) {
                dev_dbg(&client->dev, "resume without being a wakeup source\n");

                enable_irq(client->irq);

                ret = zforce_start(ts);
                if (ret < 0)
                        goto unlock;
        }

unlock:
        mutex_unlock(&input->mutex);

        return ret;
}

static SIMPLE_DEV_PM_OPS(zforce_pm_ops, zforce_suspend, zforce_resume);

static void zforce_reset(void *data)
{
        struct zforce_ts *ts = data;

        zforce_reset_assert(ts);

        udelay(10);

        if (!IS_ERR(ts->reg_vdd))
                regulator_disable(ts->reg_vdd);
}

static struct zforce_ts_platdata *zforce_parse_dt(struct device *dev)
{
        struct zforce_ts_platdata *pdata;
        struct device_node *np = dev->of_node;

        if (!np)
                return ERR_PTR(-ENOENT);

        pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
        if (!pdata) {
                dev_err(dev, "failed to allocate platform data\n");
                return ERR_PTR(-ENOMEM);
        }

        if (of_property_read_u32(np, "x-size", &pdata->x_max)) {
                dev_err(dev, "failed to get x-size property\n");
                return ERR_PTR(-EINVAL);
        }

        if (of_property_read_u32(np, "y-size", &pdata->y_max)) {
                dev_err(dev, "failed to get y-size property\n");
                return ERR_PTR(-EINVAL);
        }

        return pdata;
}

static int zforce_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
{
        const struct zforce_ts_platdata *pdata = dev_get_platdata(&client->dev);
        struct zforce_ts *ts;
        struct input_dev *input_dev;
        int ret;

        if (!pdata) {
                pdata = zforce_parse_dt(&client->dev);
                if (IS_ERR(pdata))
                        return PTR_ERR(pdata);
        }

        ts = devm_kzalloc(&client->dev, sizeof(struct zforce_ts), GFP_KERNEL);
        if (!ts)
                return -ENOMEM;

        ts->gpio_rst = devm_gpiod_get_optional(&client->dev, "reset",
                                               GPIOD_OUT_HIGH);
        if (IS_ERR(ts->gpio_rst)) {
                ret = PTR_ERR(ts->gpio_rst);
                dev_err(&client->dev,
                        "failed to request reset GPIO: %d\n", ret);
                return ret;
        }

        if (ts->gpio_rst) {
                ts->gpio_int = devm_gpiod_get_optional(&client->dev, "irq",
                                                       GPIOD_IN);
                if (IS_ERR(ts->gpio_int)) {
                        ret = PTR_ERR(ts->gpio_int);
                        dev_err(&client->dev,
                                "failed to request interrupt GPIO: %d\n", ret);
                        return ret;
                }
        } else {
                /*
                 * Deprecated GPIO handling for compatibility
                 * with legacy binding.
                 */

                /* INT GPIO */
                ts->gpio_int = devm_gpiod_get_index(&client->dev, NULL, 0,
                                                    GPIOD_IN);
                if (IS_ERR(ts->gpio_int)) {
                        ret = PTR_ERR(ts->gpio_int);
                        dev_err(&client->dev,
                                "failed to request interrupt GPIO: %d\n", ret);
                        return ret;
                }

                /* RST GPIO */
                ts->gpio_rst = devm_gpiod_get_index(&client->dev, NULL, 1,
                                            GPIOD_OUT_HIGH);
                if (IS_ERR(ts->gpio_rst)) {
                        ret = PTR_ERR(ts->gpio_rst);
                        dev_err(&client->dev,
                                "failed to request reset GPIO: %d\n", ret);
                        return ret;
                }
        }

        ts->reg_vdd = devm_regulator_get_optional(&client->dev, "vdd");
        if (IS_ERR(ts->reg_vdd)) {
                ret = PTR_ERR(ts->reg_vdd);
                if (ret == -EPROBE_DEFER)
                        return ret;
        } else {
                ret = regulator_enable(ts->reg_vdd);
                if (ret)
                        return ret;

                /*
                 * according to datasheet add 100us grace time after regular
                 * regulator enable delay.
                 */
                udelay(100);
        }

        ret = devm_add_action(&client->dev, zforce_reset, ts);
        if (ret) {
                dev_err(&client->dev, "failed to register reset action, %d\n",
                        ret);

                /* hereafter the regulator will be disabled by the action */
                if (!IS_ERR(ts->reg_vdd))
                        regulator_disable(ts->reg_vdd);

                return ret;
        }

        snprintf(ts->phys, sizeof(ts->phys),
                 "%s/input0", dev_name(&client->dev));

        input_dev = devm_input_allocate_device(&client->dev);
        if (!input_dev) {
                dev_err(&client->dev, "could not allocate input device\n");
                return -ENOMEM;
        }

        mutex_init(&ts->access_mutex);
        mutex_init(&ts->command_mutex);

        ts->pdata = pdata;
        ts->client = client;
        ts->input = input_dev;

        input_dev->name = "Neonode zForce touchscreen";
        input_dev->phys = ts->phys;
        input_dev->id.bustype = BUS_I2C;

        input_dev->open = zforce_input_open;
        input_dev->close = zforce_input_close;

        __set_bit(EV_KEY, input_dev->evbit);
        __set_bit(EV_SYN, input_dev->evbit);
        __set_bit(EV_ABS, input_dev->evbit);

        /* For multi touch */
        input_set_abs_params(input_dev, ABS_MT_POSITION_X, 0,
                             pdata->x_max, 0, 0);
        input_set_abs_params(input_dev, ABS_MT_POSITION_Y, 0,
                             pdata->y_max, 0, 0);

        input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR, 0,
                             ZFORCE_MAX_AREA, 0, 0);
        input_set_abs_params(input_dev, ABS_MT_TOUCH_MINOR, 0,
                             ZFORCE_MAX_AREA, 0, 0);
        input_set_abs_params(input_dev, ABS_MT_ORIENTATION, 0, 1, 0, 0);
        input_mt_init_slots(input_dev, ZFORCE_REPORT_POINTS, INPUT_MT_DIRECT);

        input_set_drvdata(ts->input, ts);

        init_completion(&ts->command_done);

        /*
         * The zforce pulls the interrupt low when it has data ready.
         * After it is triggered the isr thread runs until all the available
         * packets have been read and the interrupt is high again.
         * Therefore we can trigger the interrupt anytime it is low and do
         * not need to limit it to the interrupt edge.
         */
        ret = devm_request_threaded_irq(&client->dev, client->irq,
                                        zforce_irq, zforce_irq_thread,
                                        IRQF_TRIGGER_LOW | IRQF_ONESHOT,
                                        input_dev->name, ts);
        if (ret) {
                dev_err(&client->dev, "irq %d request failed\n", client->irq);
                return ret;
        }

        i2c_set_clientdata(client, ts);

        /* let the controller boot */
        zforce_reset_deassert(ts);

        ts->command_waiting = NOTIFICATION_BOOTCOMPLETE;
        if (wait_for_completion_timeout(&ts->command_done, WAIT_TIMEOUT) == 0)
                dev_warn(&client->dev, "bootcomplete timed out\n");

        /* need to start device to get version information */
        ret = zforce_command_wait(ts, COMMAND_INITIALIZE);
        if (ret) {
                dev_err(&client->dev, "unable to initialize, %d\n", ret);
                return ret;
        }

        /* this gets the firmware version among other information */
        ret = zforce_command_wait(ts, COMMAND_STATUS);
        if (ret < 0) {
                dev_err(&client->dev, "couldn't get status, %d\n", ret);
                zforce_stop(ts);
                return ret;
        }

        /* stop device and put it into sleep until it is opened */
        ret = zforce_stop(ts);
        if (ret < 0)
                return ret;

        device_set_wakeup_capable(&client->dev, true);

        ret = input_register_device(input_dev);
        if (ret) {
                dev_err(&client->dev, "could not register input device, %d\n",
                        ret);
                return ret;
        }

        return 0;
}

static struct i2c_device_id zforce_idtable[] = {
        { "zforce-ts", 0 },
        { }
};
MODULE_DEVICE_TABLE(i2c, zforce_idtable);

#ifdef CONFIG_OF
static const struct of_device_id zforce_dt_idtable[] = {
        { .compatible = "neonode,zforce" },
        {},
};
MODULE_DEVICE_TABLE(of, zforce_dt_idtable);
#endif

static struct i2c_driver zforce_driver = {
        .driver = {
                .name   = "zforce-ts",
                .pm     = &zforce_pm_ops,
                .of_match_table = of_match_ptr(zforce_dt_idtable),
        },
        .probe          = zforce_probe,
        .id_table       = zforce_idtable,
};

module_i2c_driver(zforce_driver);

MODULE_AUTHOR("Heiko Stuebner <heiko@sntech.de>");
MODULE_DESCRIPTION("zForce TouchScreen Driver");
MODULE_LICENSE("GPL");