appletouch.c

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/*
 * Apple USB Touchpad (for post-February 2005 PowerBooks and MacBooks) driver
 *
 * Copyright (C) 2001-2004 Greg Kroah-Hartman ([email protected])
 * Copyright (C) 2005-2008 Johannes Berg ([email protected])
 * Copyright (C) 2005-2008 Stelian Pop ([email protected])
 * Copyright (C) 2005      Frank Arnold ([email protected])
 * Copyright (C) 2005      Peter Osterlund ([email protected])
 * Copyright (C) 2005      Michael Hanselmann ([email protected])
 * Copyright (C) 2006      Nicolas Boichat ([email protected])
 * Copyright (C) 2007-2008 Sven Anders ([email protected])
 *
 * Thanks to Alex Harper <[email protected]> for his inputs.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/usb/input.h>

/*
 * Note: We try to keep the touchpad aspect ratio while still doing only
 * simple arithmetics:
 *  0 <= x <= (xsensors - 1) * xfact
 *  0 <= y <= (ysensors - 1) * yfact
 */
struct atp_info {
    int xsensors;               /* number of X sensors */
    int xsensors_17;            /* 17" models have more sensors */
    int ysensors;               /* number of Y sensors */
    int xfact;              /* X multiplication factor */
    int yfact;              /* Y multiplication factor */
    int datalen;                /* size of USB transfers */
    void (*callback)(struct urb *);     /* callback function */
};

static void atp_complete_geyser_1_2(struct urb *urb);
static void atp_complete_geyser_3_4(struct urb *urb);

static const struct atp_info fountain_info = {
    .xsensors   = 16,
    .xsensors_17    = 26,
    .ysensors   = 16,
    .xfact      = 64,
    .yfact      = 43,
    .datalen    = 81,
    .callback   = atp_complete_geyser_1_2,
};

static const struct atp_info geyser1_info = {
    .xsensors   = 16,
    .xsensors_17    = 26,
    .ysensors   = 16,
    .xfact      = 64,
    .yfact      = 43,
    .datalen    = 81,
    .callback   = atp_complete_geyser_1_2,
};

static const struct atp_info geyser2_info = {
    .xsensors   = 15,
    .xsensors_17    = 20,
    .ysensors   = 9,
    .xfact      = 64,
    .yfact      = 43,
    .datalen    = 64,
    .callback   = atp_complete_geyser_1_2,
};

static const struct atp_info geyser3_info = {
    .xsensors   = 20,
    .ysensors   = 10,
    .xfact      = 64,
    .yfact      = 64,
    .datalen    = 64,
    .callback   = atp_complete_geyser_3_4,
};

static const struct atp_info geyser4_info = {
    .xsensors   = 20,
    .ysensors   = 10,
    .xfact      = 64,
    .yfact      = 64,
    .datalen    = 64,
    .callback   = atp_complete_geyser_3_4,
};

#define ATP_DEVICE(prod, info)                  \
{                               \
    .match_flags = USB_DEVICE_ID_MATCH_DEVICE |     \
               USB_DEVICE_ID_MATCH_INT_CLASS |      \
               USB_DEVICE_ID_MATCH_INT_PROTOCOL,    \
    .idVendor = 0x05ac, /* Apple */             \
    .idProduct = (prod),                    \
    .bInterfaceClass = 0x03,                \
    .bInterfaceProtocol = 0x02,             \
    .driver_info = (unsigned long) &info,           \
}

/*
 * Table of devices (Product IDs) that work with this driver.
 * (The names come from Info.plist in AppleUSBTrackpad.kext,
 *  According to Info.plist Geyser IV is the same as Geyser III.)
 */

static struct usb_device_id atp_table[] = {
    /* PowerBooks Feb 2005, iBooks G4 */
    ATP_DEVICE(0x020e, fountain_info),  /* FOUNTAIN ANSI */
    ATP_DEVICE(0x020f, fountain_info),  /* FOUNTAIN ISO */
    ATP_DEVICE(0x030a, fountain_info),  /* FOUNTAIN TP ONLY */
    ATP_DEVICE(0x030b, geyser1_info),   /* GEYSER 1 TP ONLY */

    /* PowerBooks Oct 2005 */
    ATP_DEVICE(0x0214, geyser2_info),   /* GEYSER 2 ANSI */
    ATP_DEVICE(0x0215, geyser2_info),   /* GEYSER 2 ISO */
    ATP_DEVICE(0x0216, geyser2_info),   /* GEYSER 2 JIS */

    /* Core Duo MacBook & MacBook Pro */
    ATP_DEVICE(0x0217, geyser3_info),   /* GEYSER 3 ANSI */
    ATP_DEVICE(0x0218, geyser3_info),   /* GEYSER 3 ISO */
    ATP_DEVICE(0x0219, geyser3_info),   /* GEYSER 3 JIS */

    /* Core2 Duo MacBook & MacBook Pro */
    ATP_DEVICE(0x021a, geyser4_info),   /* GEYSER 4 ANSI */
    ATP_DEVICE(0x021b, geyser4_info),   /* GEYSER 4 ISO */
    ATP_DEVICE(0x021c, geyser4_info),   /* GEYSER 4 JIS */

    /* Core2 Duo MacBook3,1 */
    ATP_DEVICE(0x0229, geyser4_info),   /* GEYSER 4 HF ANSI */
    ATP_DEVICE(0x022a, geyser4_info),   /* GEYSER 4 HF ISO */
    ATP_DEVICE(0x022b, geyser4_info),   /* GEYSER 4 HF JIS */

    /* Terminating entry */
    { }
};
MODULE_DEVICE_TABLE(usb, atp_table);

/* maximum number of sensors */
#define ATP_XSENSORS    26
#define ATP_YSENSORS    16

/* amount of fuzz this touchpad generates */
#define ATP_FUZZ    16

/* maximum pressure this driver will report */
#define ATP_PRESSURE    300

/*
 * Threshold for the touchpad sensors. Any change less than ATP_THRESHOLD is
 * ignored.
 */
#define ATP_THRESHOLD    5

/* Geyser initialization constants */
#define ATP_GEYSER_MODE_READ_REQUEST_ID     1
#define ATP_GEYSER_MODE_WRITE_REQUEST_ID    9
#define ATP_GEYSER_MODE_REQUEST_VALUE       0x300
#define ATP_GEYSER_MODE_REQUEST_INDEX       0
#define ATP_GEYSER_MODE_VENDOR_VALUE        0x04

enum atp_status_bits {
    ATP_STATUS_BUTTON   = BIT(0),
    ATP_STATUS_BASE_UPDATE  = BIT(2),
    ATP_STATUS_FROM_RESET   = BIT(4),
};

/* Structure to hold all of our device specific stuff */
struct atp {
    char            phys[64];
    struct usb_device   *udev;      /* usb device */
    struct usb_interface    *intf;      /* usb interface */
    struct urb      *urb;       /* usb request block */
    u8          *data;      /* transferred data */
    struct input_dev    *input;     /* input dev */
    const struct atp_info   *info;      /* touchpad model */
    bool            open;
    bool            valid;      /* are the samples valid? */
    bool            size_detect_done;
    bool            overflow_warned;
    int         x_old;      /* last reported x/y, */
    int         y_old;      /* used for smoothing */
    signed char     xy_cur[ATP_XSENSORS + ATP_YSENSORS];
    signed char     xy_old[ATP_XSENSORS + ATP_YSENSORS];
    int         xy_acc[ATP_XSENSORS + ATP_YSENSORS];
    int         idlecount;  /* number of empty packets */
    struct work_struct  work;
};

#define dbg_dump(msg, tab) \
    if (debug > 1) {                        \
        int __i;                        \
        printk(KERN_DEBUG "appletouch: %s", msg);       \
        for (__i = 0; __i < ATP_XSENSORS + ATP_YSENSORS; __i++) \
            printk(" %02x", tab[__i]);          \
        printk("\n");                       \
    }

#define dprintk(format, a...)                       \
    do {                                \
        if (debug)                      \
            printk(KERN_DEBUG format, ##a);         \
    } while (0)

MODULE_AUTHOR("Johannes Berg");
MODULE_AUTHOR("Stelian Pop");
MODULE_AUTHOR("Frank Arnold");
MODULE_AUTHOR("Michael Hanselmann");
MODULE_AUTHOR("Sven Anders");
MODULE_DESCRIPTION("Apple PowerBook and MacBook USB touchpad driver");
MODULE_LICENSE("GPL");

/*
 * Make the threshold a module parameter
 */
static int threshold = ATP_THRESHOLD;
module_param(threshold, int, 0644);
MODULE_PARM_DESC(threshold, "Discard any change in data from a sensor"
                " (the trackpad has many of these sensors)"
                " less than this value.");

static int debug;
module_param(debug, int, 0644);
MODULE_PARM_DESC(debug, "Activate debugging output");

/*
 * By default newer Geyser devices send standard USB HID mouse
 * packets (Report ID 2). This code changes device mode, so it
 * sends raw sensor reports (Report ID 5).
 */
static int atp_geyser_init(struct atp *dev)
{
    struct usb_device *udev = dev->udev;
    char *data;
    int size;
    int i;
    int ret;

    data = kmalloc(8, GFP_KERNEL);
    if (!data) {
        dev_err(&dev->intf->dev, "Out of memory\n");
        return -ENOMEM;
    }

    size = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
            ATP_GEYSER_MODE_READ_REQUEST_ID,
            USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
            ATP_GEYSER_MODE_REQUEST_VALUE,
            ATP_GEYSER_MODE_REQUEST_INDEX, data, 8, 5000);

    if (size != 8) {
        dprintk("atp_geyser_init: read error\n");
        for (i = 0; i < 8; i++)
            dprintk("appletouch[%d]: %d\n", i, data[i]);

        dev_err(&dev->intf->dev, "Failed to read mode from device.\n");
        ret = -EIO;
        goto out_free;
    }

    /* Apply the mode switch */
    data[0] = ATP_GEYSER_MODE_VENDOR_VALUE;

    size = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
            ATP_GEYSER_MODE_WRITE_REQUEST_ID,
            USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
            ATP_GEYSER_MODE_REQUEST_VALUE,
            ATP_GEYSER_MODE_REQUEST_INDEX, data, 8, 5000);

    if (size != 8) {
        dprintk("atp_geyser_init: write error\n");
        for (i = 0; i < 8; i++)
            dprintk("appletouch[%d]: %d\n", i, data[i]);

        dev_err(&dev->intf->dev, "Failed to request geyser raw mode\n");
        ret = -EIO;
        goto out_free;
    }
    ret = 0;
out_free:
    kfree(data);
    return ret;
}

/*
 * Reinitialise the device. This usually stops stream of empty packets
 * coming from it.
 */
static void atp_reinit(struct work_struct *work)
{
    struct atp *dev = container_of(work, struct atp, work);
    int retval;

    dprintk("appletouch: putting appletouch to sleep (reinit)\n");
    atp_geyser_init(dev);

    retval = usb_submit_urb(dev->urb, GFP_ATOMIC);
    if (retval)
        dev_err(&dev->intf->dev,
            "atp_reinit: usb_submit_urb failed with error %d\n",
            retval);
}

static int atp_calculate_abs(int *xy_sensors, int nb_sensors, int fact,
                 int *z, int *fingers)
{
    int i;
    /* values to calculate mean */
    int pcum = 0, psum = 0;
    int is_increasing = 0;

    *fingers = 0;

    for (i = 0; i < nb_sensors; i++) {
        if (xy_sensors[i] < threshold) {
            if (is_increasing)
                is_increasing = 0;

            continue;
        }

        /*
         * Makes the finger detection more versatile.  For example,
         * two fingers with no gap will be detected.  Also, my
         * tests show it less likely to have intermittent loss
         * of multiple finger readings while moving around (scrolling).
         *
         * Changes the multiple finger detection to counting humps on
         * sensors (transitions from nonincreasing to increasing)
         * instead of counting transitions from low sensors (no
         * finger reading) to high sensors (finger above
         * sensor)
         *
         * - Jason Parekh <[email protected]>
         */
        if (i < 1 ||
            (!is_increasing && xy_sensors[i - 1] < xy_sensors[i])) {
            (*fingers)++;
            is_increasing = 1;
        } else if (i > 0 && (xy_sensors[i - 1] - xy_sensors[i] > threshold)) {
            is_increasing = 0;
        }

        /*
         * Subtracts threshold so a high sensor that just passes the
         * threshold won't skew the calculated absolute coordinate.
         * Fixes an issue where slowly moving the mouse would
         * occasionally jump a number of pixels (slowly moving the
         * finger makes this issue most apparent.)
         */
        pcum += (xy_sensors[i] - threshold) * i;
        psum += (xy_sensors[i] - threshold);
    }

    if (psum > 0) {
        *z = psum;
        return pcum * fact / psum;
    }

    return 0;
}

static inline void atp_report_fingers(struct input_dev *input, int fingers)
{
    input_report_key(input, BTN_TOOL_FINGER, fingers == 1);
    input_report_key(input, BTN_TOOL_DOUBLETAP, fingers == 2);
    input_report_key(input, BTN_TOOL_TRIPLETAP, fingers > 2);
}

/* Check URB status and for correct length of data package */

#define ATP_URB_STATUS_SUCCESS      0
#define ATP_URB_STATUS_ERROR        1
#define ATP_URB_STATUS_ERROR_FATAL  2

static int atp_status_check(struct urb *urb)
{
    struct atp *dev = urb->context;
    struct usb_interface *intf = dev->intf;

    switch (urb->status) {
    case 0:
        /* success */
        break;
    case -EOVERFLOW:
        if (!dev->overflow_warned) {
            dev_warn(&intf->dev,
                "appletouch: OVERFLOW with data length %d, actual length is %d\n",
                dev->info->datalen, dev->urb->actual_length);
            dev->overflow_warned = true;
        }
    case -ECONNRESET:
    case -ENOENT:
    case -ESHUTDOWN:
        /* This urb is terminated, clean up */
        dev_dbg(&intf->dev,
            "atp_complete: urb shutting down with status: %d\n",
            urb->status);
        return ATP_URB_STATUS_ERROR_FATAL;

    default:
        dev_dbg(&intf->dev,
            "atp_complete: nonzero urb status received: %d\n",
            urb->status);
        return ATP_URB_STATUS_ERROR;
    }

    /* drop incomplete datasets */
    if (dev->urb->actual_length != dev->info->datalen) {
        dprintk("appletouch: incomplete data package"
            " (first byte: %d, length: %d).\n",
            dev->data[0], dev->urb->actual_length);
        return ATP_URB_STATUS_ERROR;
    }

    return ATP_URB_STATUS_SUCCESS;
}

static void atp_detect_size(struct atp *dev)
{
    int i;

    /* 17" Powerbooks have extra X sensors */
    for (i = dev->info->xsensors; i < ATP_XSENSORS; i++) {
        if (dev->xy_cur[i]) {

            dev_info(&dev->intf->dev,
                "appletouch: 17\" model detected.\n");

            input_set_abs_params(dev->input, ABS_X, 0,
                         (dev->info->xsensors_17 - 1) *
                            dev->info->xfact - 1,
                         ATP_FUZZ, 0);
            break;
        }
    }
}

/*
 * USB interrupt callback functions
 */

/* Interrupt function for older touchpads: FOUNTAIN/GEYSER1/GEYSER2 */

static void atp_complete_geyser_1_2(struct urb *urb)
{
    int x, y, x_z, y_z, x_f, y_f;
    int retval, i, j;
    int key;
    struct atp *dev = urb->context;
    int status = atp_status_check(urb);

    if (status == ATP_URB_STATUS_ERROR_FATAL)
        return;
    else if (status == ATP_URB_STATUS_ERROR)
        goto exit;

    /* reorder the sensors values */
    if (dev->info == &geyser2_info) {
        memset(dev->xy_cur, 0, sizeof(dev->xy_cur));

        /*
         * The values are laid out like this:
         * Y1, Y2, -, Y3, Y4, -, ..., X1, X2, -, X3, X4, -, ...
         * '-' is an unused value.
         */

        /* read X values */
        for (i = 0, j = 19; i < 20; i += 2, j += 3) {
            dev->xy_cur[i] = dev->data[j];
            dev->xy_cur[i + 1] = dev->data[j + 1];
        }

        /* read Y values */
        for (i = 0, j = 1; i < 9; i += 2, j += 3) {
            dev->xy_cur[ATP_XSENSORS + i] = dev->data[j];
            dev->xy_cur[ATP_XSENSORS + i + 1] = dev->data[j + 1];
        }
    } else {
        for (i = 0; i < 8; i++) {
            /* X values */
            dev->xy_cur[i +  0] = dev->data[5 * i +  2];
            dev->xy_cur[i +  8] = dev->data[5 * i +  4];
            dev->xy_cur[i + 16] = dev->data[5 * i + 42];
            if (i < 2)
                dev->xy_cur[i + 24] = dev->data[5 * i + 44];

            /* Y values */
            dev->xy_cur[ATP_XSENSORS + i] = dev->data[5 * i +  1];
            dev->xy_cur[ATP_XSENSORS + i + 8] = dev->data[5 * i + 3];
        }
    }

    dbg_dump("sample", dev->xy_cur);

    if (!dev->valid) {
        /* first sample */
        dev->valid = true;
        dev->x_old = dev->y_old = -1;

        /* Store first sample */
        memcpy(dev->xy_old, dev->xy_cur, sizeof(dev->xy_old));

        /* Perform size detection, if not done already */
        if (unlikely(!dev->size_detect_done)) {
            atp_detect_size(dev);
            dev->size_detect_done = 1;
            goto exit;
        }
    }

    for (i = 0; i < ATP_XSENSORS + ATP_YSENSORS; i++) {
        /* accumulate the change */
        signed char change = dev->xy_old[i] - dev->xy_cur[i];
        dev->xy_acc[i] -= change;

        /* prevent down drifting */
        if (dev->xy_acc[i] < 0)
            dev->xy_acc[i] = 0;
    }

    memcpy(dev->xy_old, dev->xy_cur, sizeof(dev->xy_old));

    dbg_dump("accumulator", dev->xy_acc);

    x = atp_calculate_abs(dev->xy_acc, ATP_XSENSORS,
                  dev->info->xfact, &x_z, &x_f);
    y = atp_calculate_abs(dev->xy_acc + ATP_XSENSORS, ATP_YSENSORS,
                  dev->info->yfact, &y_z, &y_f);
    key = dev->data[dev->info->datalen - 1] & ATP_STATUS_BUTTON;

    if (x && y) {
        if (dev->x_old != -1) {
            x = (dev->x_old * 3 + x) >> 2;
            y = (dev->y_old * 3 + y) >> 2;
            dev->x_old = x;
            dev->y_old = y;

            if (debug > 1)
                printk(KERN_DEBUG "appletouch: "
                    "X: %3d Y: %3d Xz: %3d Yz: %3d\n",
                    x, y, x_z, y_z);

            input_report_key(dev->input, BTN_TOUCH, 1);
            input_report_abs(dev->input, ABS_X, x);
            input_report_abs(dev->input, ABS_Y, y);
            input_report_abs(dev->input, ABS_PRESSURE,
                     min(ATP_PRESSURE, x_z + y_z));
            atp_report_fingers(dev->input, max(x_f, y_f));
        }
        dev->x_old = x;
        dev->y_old = y;

    } else if (!x && !y) {

        dev->x_old = dev->y_old = -1;
        input_report_key(dev->input, BTN_TOUCH, 0);
        input_report_abs(dev->input, ABS_PRESSURE, 0);
        atp_report_fingers(dev->input, 0);

        /* reset the accumulator on release */
        memset(dev->xy_acc, 0, sizeof(dev->xy_acc));
    }

    input_report_key(dev->input, BTN_LEFT, key);
    input_sync(dev->input);

 exit:
    retval = usb_submit_urb(dev->urb, GFP_ATOMIC);
    if (retval)
        dev_err(&dev->intf->dev,
            "atp_complete: usb_submit_urb failed with result %d\n",
            retval);
}

/* Interrupt function for older touchpads: GEYSER3/GEYSER4 */

static void atp_complete_geyser_3_4(struct urb *urb)
{
    int x, y, x_z, y_z, x_f, y_f;
    int retval, i, j;
    int key;
    struct atp *dev = urb->context;
    int status = atp_status_check(urb);

    if (status == ATP_URB_STATUS_ERROR_FATAL)
        return;
    else if (status == ATP_URB_STATUS_ERROR)
        goto exit;

    /* Reorder the sensors values:
     *
     * The values are laid out like this:
     * -, Y1, Y2, -, Y3, Y4, -, ..., -, X1, X2, -, X3, X4, ...
     * '-' is an unused value.
     */

    /* read X values */
    for (i = 0, j = 19; i < 20; i += 2, j += 3) {
        dev->xy_cur[i] = dev->data[j + 1];
        dev->xy_cur[i + 1] = dev->data[j + 2];
    }
    /* read Y values */
    for (i = 0, j = 1; i < 9; i += 2, j += 3) {
        dev->xy_cur[ATP_XSENSORS + i] = dev->data[j + 1];
        dev->xy_cur[ATP_XSENSORS + i + 1] = dev->data[j + 2];
    }

    dbg_dump("sample", dev->xy_cur);

    /* Just update the base values (i.e. touchpad in untouched state) */
    if (dev->data[dev->info->datalen - 1] & ATP_STATUS_BASE_UPDATE) {

        dprintk("appletouch: updated base values\n");

        memcpy(dev->xy_old, dev->xy_cur, sizeof(dev->xy_old));
        goto exit;
    }

    for (i = 0; i < ATP_XSENSORS + ATP_YSENSORS; i++) {
        /* calculate the change */
        dev->xy_acc[i] = dev->xy_cur[i] - dev->xy_old[i];

        /* this is a round-robin value, so couple with that */
        if (dev->xy_acc[i] > 127)
            dev->xy_acc[i] -= 256;

        if (dev->xy_acc[i] < -127)
            dev->xy_acc[i] += 256;

        /* prevent down drifting */
        if (dev->xy_acc[i] < 0)
            dev->xy_acc[i] = 0;
    }

    dbg_dump("accumulator", dev->xy_acc);

    x = atp_calculate_abs(dev->xy_acc, ATP_XSENSORS,
                  dev->info->xfact, &x_z, &x_f);
    y = atp_calculate_abs(dev->xy_acc + ATP_XSENSORS, ATP_YSENSORS,
                  dev->info->yfact, &y_z, &y_f);
    key = dev->data[dev->info->datalen - 1] & ATP_STATUS_BUTTON;

    if (x && y) {
        if (dev->x_old != -1) {
            x = (dev->x_old * 3 + x) >> 2;
            y = (dev->y_old * 3 + y) >> 2;
            dev->x_old = x;
            dev->y_old = y;

            if (debug > 1)
                printk(KERN_DEBUG "appletouch: X: %3d Y: %3d "
                       "Xz: %3d Yz: %3d\n",
                       x, y, x_z, y_z);

            input_report_key(dev->input, BTN_TOUCH, 1);
            input_report_abs(dev->input, ABS_X, x);
            input_report_abs(dev->input, ABS_Y, y);
            input_report_abs(dev->input, ABS_PRESSURE,
                     min(ATP_PRESSURE, x_z + y_z));
            atp_report_fingers(dev->input, max(x_f, y_f));
        }
        dev->x_old = x;
        dev->y_old = y;

    } else if (!x && !y) {

        dev->x_old = dev->y_old = -1;
        input_report_key(dev->input, BTN_TOUCH, 0);
        input_report_abs(dev->input, ABS_PRESSURE, 0);
        atp_report_fingers(dev->input, 0);

        /* reset the accumulator on release */
        memset(dev->xy_acc, 0, sizeof(dev->xy_acc));
    }

    input_report_key(dev->input, BTN_LEFT, key);
    input_sync(dev->input);

    /*
     * Geysers 3/4 will continue to send packets continually after
     * the first touch unless reinitialised. Do so if it's been
     * idle for a while in order to avoid waking the kernel up
     * several hundred times a second.
     */

    /*
     * Button must not be pressed when entering suspend,
     * otherwise we will never release the button.
     */
    if (!x && !y && !key) {
        dev->idlecount++;
        if (dev->idlecount == 10) {
            dev->x_old = dev->y_old = -1;
            dev->idlecount = 0;
            schedule_work(&dev->work);
            /* Don't resubmit urb here, wait for reinit */
            return;
        }
    } else
        dev->idlecount = 0;

 exit:
    retval = usb_submit_urb(dev->urb, GFP_ATOMIC);
    if (retval)
        dev_err(&dev->intf->dev,
            "atp_complete: usb_submit_urb failed with result %d\n",
            retval);
}

static int atp_open(struct input_dev *input)
{
    struct atp *dev = input_get_drvdata(input);

    if (usb_submit_urb(dev->urb, GFP_ATOMIC))
        return -EIO;

    dev->open = 1;
    return 0;
}

static void atp_close(struct input_dev *input)
{
    struct atp *dev = input_get_drvdata(input);

    usb_kill_urb(dev->urb);
    cancel_work_sync(&dev->work);
    dev->open = 0;
}

static int atp_handle_geyser(struct atp *dev)
{
    if (dev->info != &fountain_info) {
        /* switch to raw sensor mode */
        if (atp_geyser_init(dev))
            return -EIO;

        dev_info(&dev->intf->dev, "Geyser mode initialized.\n");
    }

    return 0;
}

static int atp_probe(struct usb_interface *iface,
             const struct usb_device_id *id)
{
    struct atp *dev;
    struct input_dev *input_dev;
    struct usb_device *udev = interface_to_usbdev(iface);
    struct usb_host_interface *iface_desc;
    struct usb_endpoint_descriptor *endpoint;
    int int_in_endpointAddr = 0;
    int i, error = -ENOMEM;
    const struct atp_info *info = (const struct atp_info *)id->driver_info;

    /* set up the endpoint information */
    /* use only the first interrupt-in endpoint */
    iface_desc = iface->cur_altsetting;
    for (i = 0; i < iface_desc->desc.bNumEndpoints; i++) {
        endpoint = &iface_desc->endpoint[i].desc;
        if (!int_in_endpointAddr && usb_endpoint_is_int_in(endpoint)) {
            /* we found an interrupt in endpoint */
            int_in_endpointAddr = endpoint->bEndpointAddress;
            break;
        }
    }
    if (!int_in_endpointAddr) {
        dev_err(&iface->dev, "Could not find int-in endpoint\n");
        return -EIO;
    }

    /* allocate memory for our device state and initialize it */
    dev = kzalloc(sizeof(struct atp), GFP_KERNEL);
    input_dev = input_allocate_device();
    if (!dev || !input_dev) {
        dev_err(&iface->dev, "Out of memory\n");
        goto err_free_devs;
    }

    dev->udev = udev;
    dev->intf = iface;
    dev->input = input_dev;
    dev->info = info;
    dev->overflow_warned = false;

    dev->urb = usb_alloc_urb(0, GFP_KERNEL);
    if (!dev->urb)
        goto err_free_devs;

    dev->data = usb_alloc_coherent(dev->udev, dev->info->datalen, GFP_KERNEL,
                       &dev->urb->transfer_dma);
    if (!dev->data)
        goto err_free_urb;

    usb_fill_int_urb(dev->urb, udev,
             usb_rcvintpipe(udev, int_in_endpointAddr),
             dev->data, dev->info->datalen,
             dev->info->callback, dev, 1);

    error = atp_handle_geyser(dev);
    if (error)
        goto err_free_buffer;

    usb_make_path(udev, dev->phys, sizeof(dev->phys));
    strlcat(dev->phys, "/input0", sizeof(dev->phys));

    input_dev->name = "appletouch";
    input_dev->phys = dev->phys;
    usb_to_input_id(dev->udev, &input_dev->id);
    input_dev->dev.parent = &iface->dev;

    input_set_drvdata(input_dev, dev);

    input_dev->open = atp_open;
    input_dev->close = atp_close;

    set_bit(EV_ABS, input_dev->evbit);

    input_set_abs_params(input_dev, ABS_X, 0,
                 (dev->info->xsensors - 1) * dev->info->xfact - 1,
                 ATP_FUZZ, 0);
    input_set_abs_params(input_dev, ABS_Y, 0,
                 (dev->info->ysensors - 1) * dev->info->yfact - 1,
                 ATP_FUZZ, 0);
    input_set_abs_params(input_dev, ABS_PRESSURE, 0, ATP_PRESSURE, 0, 0);

    set_bit(EV_KEY, input_dev->evbit);
    set_bit(BTN_TOUCH, input_dev->keybit);
    set_bit(BTN_TOOL_FINGER, input_dev->keybit);
    set_bit(BTN_TOOL_DOUBLETAP, input_dev->keybit);
    set_bit(BTN_TOOL_TRIPLETAP, input_dev->keybit);
    set_bit(BTN_LEFT, input_dev->keybit);

    error = input_register_device(dev->input);
    if (error)
        goto err_free_buffer;

    /* save our data pointer in this interface device */
    usb_set_intfdata(iface, dev);

    INIT_WORK(&dev->work, atp_reinit);

    return 0;

 err_free_buffer:
    usb_free_coherent(dev->udev, dev->info->datalen,
              dev->data, dev->urb->transfer_dma);
 err_free_urb:
    usb_free_urb(dev->urb);
 err_free_devs:
    usb_set_intfdata(iface, NULL);
    kfree(dev);
    input_free_device(input_dev);
    return error;
}

static void atp_disconnect(struct usb_interface *iface)
{
    struct atp *dev = usb_get_intfdata(iface);

    usb_set_intfdata(iface, NULL);
    if (dev) {
        usb_kill_urb(dev->urb);
        input_unregister_device(dev->input);
        usb_free_coherent(dev->udev, dev->info->datalen,
                  dev->data, dev->urb->transfer_dma);
        usb_free_urb(dev->urb);
        kfree(dev);
    }
    dev_info(&iface->dev, "input: appletouch disconnected\n");
}

static int atp_recover(struct atp *dev)
{
    int error;

    error = atp_handle_geyser(dev);
    if (error)
        return error;

    if (dev->open && usb_submit_urb(dev->urb, GFP_ATOMIC))
        return -EIO;

    return 0;
}

static int atp_suspend(struct usb_interface *iface, pm_message_t message)
{
    struct atp *dev = usb_get_intfdata(iface);

    usb_kill_urb(dev->urb);
    return 0;
}

static int atp_resume(struct usb_interface *iface)
{
    struct atp *dev = usb_get_intfdata(iface);

    if (dev->open && usb_submit_urb(dev->urb, GFP_ATOMIC))
        return -EIO;

    return 0;
}

static int atp_reset_resume(struct usb_interface *iface)
{
    struct atp *dev = usb_get_intfdata(iface);

    return atp_recover(dev);
}

static struct usb_driver atp_driver = {
    .name       = "appletouch",
    .probe      = atp_probe,
    .disconnect = atp_disconnect,
    .suspend    = atp_suspend,
    .resume     = atp_resume,
    .reset_resume   = atp_reset_resume,
    .id_table   = atp_table,
};

module_usb_driver(atp_driver);