help with LCD touch configuration using tslib

Code:
static int check_fd(struct tslib_input *i)
{
        struct tsdev *ts = i->module.dev;
        int version;
        long evbit[BITS_TO_LONGS(EV_CNT)];
        long absbit[BITS_TO_LONGS(ABS_CNT)];
        long keybit[BITS_TO_LONGS(KEY_CNT)];
        long synbit[BITS_TO_LONGS(SYN_CNT)];

        if (ioctl(ts->fd, EVIOCGVERSION, &version) < 0) {
                fprintf(stderr, "tslib: Selected device is not a Linux input event device\n");
                return -1;
        }

        /* support version EV_VERSION 0x010000 and 0x010001
         * this check causes more troubles than it solves here */
        if (version < EV_VERSION)
                fprintf(stderr, "tslib: Warning: Selected device uses a different version of the event protocol than tslib was compiled for\n");

        if ( (ioctl(ts->fd, EVIOCGBIT(0, sizeof(evbit)), evbit) < 0) ||
                !(evbit[BIT_WORD(EV_ABS)] & BIT_MASK(EV_ABS)) ||
                !(evbit[BIT_WORD(EV_KEY)] & BIT_MASK(EV_KEY)) ) {
                fprintf(stderr, "tslib: Selected device is not a touchscreen (must support ABS and KEY event types)\n");
                return -1;
        }

        if ((ioctl(ts->fd, EVIOCGBIT(EV_ABS, sizeof(absbit)), absbit)) < 0 ||
            !(absbit[BIT_WORD(ABS_X)] & BIT_MASK(ABS_X)) ||
            !(absbit[BIT_WORD(ABS_Y)] & BIT_MASK(ABS_Y))) {
                if (!(absbit[BIT_WORD(ABS_MT_POSITION_X)] & BIT_MASK(ABS_MT_POSITION_X)) ||
                    !(absbit[BIT_WORD(ABS_MT_POSITION_Y)] & BIT_MASK(ABS_MT_POSITION_Y))) {
                        fprintf(stderr, "tslib: Selected device is not a touchscreen (must support ABS_X/Y or ABS_MT_POSITION_X/Y events)\n");
                        return -1;
                }
        }

        /* Since some touchscreens (eg. infrared) physically can't measure pressure,
         * the input system doesn't report it on those. Tslib relies on pressure, thus
         * we set it to constant 255. It's still controlled by BTN_TOUCH/BTN_LEFT -
         * when not touched, the pressure is forced to 0. */
        if (!(absbit[BIT_WORD(ABS_PRESSURE)] & BIT_MASK(ABS_PRESSURE)))
                i->no_pressure = 1;

        if ((ioctl(ts->fd, EVIOCGBIT(EV_KEY, sizeof(keybit)), keybit) < 0) ||
                !(keybit[BIT_WORD(BTN_TOUCH)] & BIT_MASK(BTN_TOUCH) ||
                  keybit[BIT_WORD(BTN_LEFT)] & BIT_MASK(BTN_LEFT))) {
                fprintf(stderr, "tslib: Selected device is not a touchscreen (must support BTN_TOUCH or BTN_LEFT events)\n");
                return -1;
        }

        /* Remember whether we have a multitouch device. We need to know for ABS_X,
         * ABS_Y and ABS_PRESSURE data. */
        if ((absbit[BIT_WORD(ABS_MT_POSITION_X)] & BIT_MASK(ABS_MT_POSITION_X)) &&
            (absbit[BIT_WORD(ABS_MT_POSITION_Y)] & BIT_MASK(ABS_MT_POSITION_Y)))
                i->mt = 1;

        /* remember if we have a device that doesn't support pressure. We have to
         * set pressure ourselves in this case. */
        if (i->mt && !(absbit[BIT_WORD(ABS_MT_PRESSURE)] & BIT_MASK(ABS_MT_PRESSURE)))
                i->no_pressure = 1;

        if (evbit[BIT_WORD(EV_SYN)] & BIT_MASK(EV_SYN))
                i->using_syn = 1;

        if ((ioctl(ts->fd, EVIOCGBIT(EV_SYN, sizeof(synbit)), synbit)) == -1)
                fprintf(stderr, "tslib: ioctl error\n");

        /* remember whether we have a multitouch type A device */
        if (i->mt && synbit[BIT_WORD(SYN_MT_REPORT)] & BIT_MASK(SYN_MT_REPORT) &&
            !(absbit[BIT_WORD(ABS_MT_SLOT)] & BIT_MASK(ABS_MT_SLOT)))
                i->type_a = 1;

        if (i->grab_events == GRAB_EVENTS_WANTED) {
                if (ioctl(ts->fd, EVIOCGRAB, (void *)1)) {
                        fprintf(stderr, "tslib: Unable to grab selected input device\n");
                        return -1;
                }
                i->grab_events = GRAB_EVENTS_ACTIVE;
        }

        return ts->fd;
}