/*
 *   imon.c:    input and display driver for SoundGraph iMON IR/VFD/LCD
 *
 *   Copyright(C) 2010  Jarod Wilson <jarod@wilsonet.com>
 *   Portions based on the original lirc_imon driver,
 *      Copyright(C) 2004  Venky Raju(dev@venky.ws)
 *
 *   Huge thanks to R. Geoff Newbury for invaluable debugging on the
 *   0xffdc iMON devices, and for sending me one to hack on, without
 *   which the support for them wouldn't be nearly as good. Thanks
 *   also to the numerous 0xffdc device owners that tested auto-config
 *   support for me and provided debug dumps from their devices.
 *
 *   imon 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/ktime.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/ratelimit.h>

#include <linux/input.h>
#include <linux/usb.h>
#include <linux/usb/input.h>
#include <media/rc-core.h>

#include <linux/timer.h>

#define MOD_AUTHOR      "Jarod Wilson <jarod@wilsonet.com>"
#define MOD_DESC        "Driver for SoundGraph iMON MultiMedia IR/Display"
#define MOD_NAME        "imon"
#define MOD_VERSION     "0.9.4"

#define DISPLAY_MINOR_BASE      144
#define DEVICE_NAME     "lcd%d"

#define BUF_CHUNK_SIZE  8
#define BUF_SIZE        128

#define BIT_DURATION    250     /* each bit received is 250us */

#define IMON_CLOCK_ENABLE_PACKETS       2

/*** P R O T O T Y P E S ***/

/* USB Callback prototypes */
static int imon_probe(struct usb_interface *interface,
                      const struct usb_device_id *id);
static void imon_disconnect(struct usb_interface *interface);
static void usb_rx_callback_intf0(struct urb *urb);
static void usb_rx_callback_intf1(struct urb *urb);
static void usb_tx_callback(struct urb *urb);

/* suspend/resume support */
static int imon_resume(struct usb_interface *intf);
static int imon_suspend(struct usb_interface *intf, pm_message_t message);

/* Display file_operations function prototypes */
static int display_open(struct inode *inode, struct file *file);
static int display_close(struct inode *inode, struct file *file);

/* VFD write operation */
static ssize_t vfd_write(struct file *file, const char __user *buf,
                         size_t n_bytes, loff_t *pos);

/* LCD file_operations override function prototypes */
static ssize_t lcd_write(struct file *file, const char __user *buf,
                         size_t n_bytes, loff_t *pos);

/*** G L O B A L S ***/

struct imon_panel_key_table {
        u64 hw_code;
        u32 keycode;
};

struct imon_usb_dev_descr {
        __u16 flags;
#define IMON_NO_FLAGS 0
#define IMON_NEED_20MS_PKT_DELAY 1
        struct imon_panel_key_table key_table[];
};

struct imon_context {
        struct device *dev;
        /* Newer devices have two interfaces */
        struct usb_device *usbdev_intf0;
        struct usb_device *usbdev_intf1;

        bool display_supported;         /* not all controllers do */
        bool display_isopen;            /* display port has been opened */
        bool rf_device;                 /* true if iMON 2.4G LT/DT RF device */
        bool rf_isassociating;          /* RF remote associating */
        bool dev_present_intf0;         /* USB device presence, interface 0 */
        bool dev_present_intf1;         /* USB device presence, interface 1 */

        struct mutex lock;              /* to lock this object */
        wait_queue_head_t remove_ok;    /* For unexpected USB disconnects */

        struct usb_endpoint_descriptor *rx_endpoint_intf0;
        struct usb_endpoint_descriptor *rx_endpoint_intf1;
        struct usb_endpoint_descriptor *tx_endpoint;
        struct urb *rx_urb_intf0;
        struct urb *rx_urb_intf1;
        struct urb *tx_urb;
        bool tx_control;
        unsigned char usb_rx_buf[8];
        unsigned char usb_tx_buf[8];
        unsigned int send_packet_delay;

        struct tx_t {
                unsigned char data_buf[35];     /* user data buffer */
                struct completion finished;     /* wait for write to finish */
                bool busy;                      /* write in progress */
                int status;                     /* status of tx completion */
        } tx;

        u16 vendor;                     /* usb vendor ID */
        u16 product;                    /* usb product ID */

        struct rc_dev *rdev;            /* rc-core device for remote */
        struct input_dev *idev;         /* input device for panel & IR mouse */
        struct input_dev *touch;        /* input device for touchscreen */

        spinlock_t kc_lock;             /* make sure we get keycodes right */
        u32 kc;                         /* current input keycode */
        u32 last_keycode;               /* last reported input keycode */
        u32 rc_scancode;                /* the computed remote scancode */
        u8 rc_toggle;                   /* the computed remote toggle bit */
        u64 rc_proto;                   /* iMON or MCE (RC6) IR protocol? */
        bool release_code;              /* some keys send a release code */

        u8 display_type;                /* store the display type */
        bool pad_mouse;                 /* toggle kbd(0)/mouse(1) mode */

        char name_rdev[128];            /* rc input device name */
        char phys_rdev[64];             /* rc input device phys path */

        char name_idev[128];            /* input device name */
        char phys_idev[64];             /* input device phys path */

        char name_touch[128];           /* touch screen name */
        char phys_touch[64];            /* touch screen phys path */
        struct timer_list ttimer;       /* touch screen timer */
        int touch_x;                    /* x coordinate on touchscreen */
        int touch_y;                    /* y coordinate on touchscreen */
        struct imon_usb_dev_descr *dev_descr; /* device description with key
                                                 table for front panels */
};

#define TOUCH_TIMEOUT   (HZ/30)

/* vfd character device file operations */
static const struct file_operations vfd_fops = {
        .owner          = THIS_MODULE,
        .open           = &display_open,
        .write          = &vfd_write,
        .release        = &display_close,
        .llseek         = noop_llseek,
};

/* lcd character device file operations */
static const struct file_operations lcd_fops = {
        .owner          = THIS_MODULE,
        .open           = &display_open,
        .write          = &lcd_write,
        .release        = &display_close,
        .llseek         = noop_llseek,
};

enum {
        IMON_DISPLAY_TYPE_AUTO = 0,
        IMON_DISPLAY_TYPE_VFD  = 1,
        IMON_DISPLAY_TYPE_LCD  = 2,
        IMON_DISPLAY_TYPE_VGA  = 3,
        IMON_DISPLAY_TYPE_NONE = 4,
};

enum {
        IMON_KEY_IMON   = 0,
        IMON_KEY_MCE    = 1,
        IMON_KEY_PANEL  = 2,
};

static struct usb_class_driver imon_vfd_class = {
        .name           = DEVICE_NAME,
        .fops           = &vfd_fops,
        .minor_base     = DISPLAY_MINOR_BASE,
};

static struct usb_class_driver imon_lcd_class = {
        .name           = DEVICE_NAME,
        .fops           = &lcd_fops,
        .minor_base     = DISPLAY_MINOR_BASE,
};

/* imon receiver front panel/knob key table */
static const struct imon_usb_dev_descr imon_default_table = {
        .flags = IMON_NO_FLAGS,
        .key_table = {
                { 0x000000000f00ffeell, KEY_MEDIA }, /* Go */
                { 0x000000001200ffeell, KEY_UP },
                { 0x000000001300ffeell, KEY_DOWN },
                { 0x000000001400ffeell, KEY_LEFT },
                { 0x000000001500ffeell, KEY_RIGHT },
                { 0x000000001600ffeell, KEY_ENTER },
                { 0x000000001700ffeell, KEY_ESC },
                { 0x000000001f00ffeell, KEY_AUDIO },
                { 0x000000002000ffeell, KEY_VIDEO },
                { 0x000000002100ffeell, KEY_CAMERA },
                { 0x000000002700ffeell, KEY_DVD },
                { 0x000000002300ffeell, KEY_TV },
                { 0x000000002b00ffeell, KEY_EXIT },
                { 0x000000002c00ffeell, KEY_SELECT },
                { 0x000000002d00ffeell, KEY_MENU },
                { 0x000000000500ffeell, KEY_PREVIOUS },
                { 0x000000000700ffeell, KEY_REWIND },
                { 0x000000000400ffeell, KEY_STOP },
                { 0x000000003c00ffeell, KEY_PLAYPAUSE },
                { 0x000000000800ffeell, KEY_FASTFORWARD },
                { 0x000000000600ffeell, KEY_NEXT },
                { 0x000000010000ffeell, KEY_RIGHT },
                { 0x000001000000ffeell, KEY_LEFT },
                { 0x000000003d00ffeell, KEY_SELECT },
                { 0x000100000000ffeell, KEY_VOLUMEUP },
                { 0x010000000000ffeell, KEY_VOLUMEDOWN },
                { 0x000000000100ffeell, KEY_MUTE },
                /* 0xffdc iMON MCE VFD */
                { 0x00010000ffffffeell, KEY_VOLUMEUP },
                { 0x01000000ffffffeell, KEY_VOLUMEDOWN },
                { 0x00000001ffffffeell, KEY_MUTE },
                { 0x0000000fffffffeell, KEY_MEDIA },
                { 0x00000012ffffffeell, KEY_UP },
                { 0x00000013ffffffeell, KEY_DOWN },
                { 0x00000014ffffffeell, KEY_LEFT },
                { 0x00000015ffffffeell, KEY_RIGHT },
                { 0x00000016ffffffeell, KEY_ENTER },
                { 0x00000017ffffffeell, KEY_ESC },
                /* iMON Knob values */
                { 0x000100ffffffffeell, KEY_VOLUMEUP },
                { 0x010000ffffffffeell, KEY_VOLUMEDOWN },
                { 0x000008ffffffffeell, KEY_MUTE },
                { 0, KEY_RESERVED },
        }
};

static const struct imon_usb_dev_descr imon_OEM_VFD = {
        .flags = IMON_NEED_20MS_PKT_DELAY,
        .key_table = {
                { 0x000000000f00ffeell, KEY_MEDIA }, /* Go */
                { 0x000000001200ffeell, KEY_UP },
                { 0x000000001300ffeell, KEY_DOWN },
                { 0x000000001400ffeell, KEY_LEFT },
                { 0x000000001500ffeell, KEY_RIGHT },
                { 0x000000001600ffeell, KEY_ENTER },
                { 0x000000001700ffeell, KEY_ESC },
                { 0x000000001f00ffeell, KEY_AUDIO },
                { 0x000000002b00ffeell, KEY_EXIT },
                { 0x000000002c00ffeell, KEY_SELECT },
                { 0x000000002d00ffeell, KEY_MENU },
                { 0x000000000500ffeell, KEY_PREVIOUS },
                { 0x000000000700ffeell, KEY_REWIND },
                { 0x000000000400ffeell, KEY_STOP },
                { 0x000000003c00ffeell, KEY_PLAYPAUSE },
                { 0x000000000800ffeell, KEY_FASTFORWARD },
                { 0x000000000600ffeell, KEY_NEXT },
                { 0x000000010000ffeell, KEY_RIGHT },
                { 0x000001000000ffeell, KEY_LEFT },
                { 0x000000003d00ffeell, KEY_SELECT },
                { 0x000100000000ffeell, KEY_VOLUMEUP },
                { 0x010000000000ffeell, KEY_VOLUMEDOWN },
                { 0x000000000100ffeell, KEY_MUTE },
                /* 0xffdc iMON MCE VFD */
                { 0x00010000ffffffeell, KEY_VOLUMEUP },
                { 0x01000000ffffffeell, KEY_VOLUMEDOWN },
                { 0x00000001ffffffeell, KEY_MUTE },
                { 0x0000000fffffffeell, KEY_MEDIA },
                { 0x00000012ffffffeell, KEY_UP },
                { 0x00000013ffffffeell, KEY_DOWN },
                { 0x00000014ffffffeell, KEY_LEFT },
                { 0x00000015ffffffeell, KEY_RIGHT },
                { 0x00000016ffffffeell, KEY_ENTER },
                { 0x00000017ffffffeell, KEY_ESC },
                /* iMON Knob values */
                { 0x000100ffffffffeell, KEY_VOLUMEUP },
                { 0x010000ffffffffeell, KEY_VOLUMEDOWN },
                { 0x000008ffffffffeell, KEY_MUTE },
                { 0, KEY_RESERVED },
        }
};

/* imon receiver front panel/knob key table for DH102*/
static const struct imon_usb_dev_descr imon_DH102 = {
        .flags = IMON_NO_FLAGS,
        .key_table = {
                { 0x000100000000ffeell, KEY_VOLUMEUP },
                { 0x010000000000ffeell, KEY_VOLUMEDOWN },
                { 0x000000010000ffeell, KEY_MUTE },
                { 0x0000000f0000ffeell, KEY_MEDIA },
                { 0x000000120000ffeell, KEY_UP },
                { 0x000000130000ffeell, KEY_DOWN },
                { 0x000000140000ffeell, KEY_LEFT },
                { 0x000000150000ffeell, KEY_RIGHT },
                { 0x000000160000ffeell, KEY_ENTER },
                { 0x000000170000ffeell, KEY_ESC },
                { 0x0000002b0000ffeell, KEY_EXIT },
                { 0x0000002c0000ffeell, KEY_SELECT },
                { 0x0000002d0000ffeell, KEY_MENU },
                { 0, KEY_RESERVED }
        }
};

/*
 * USB Device ID for iMON USB Control Boards
 *
 * The Windows drivers contain 6 different inf files, more or less one for
 * each new device until the 0x0034-0x0046 devices, which all use the same
 * driver. Some of the devices in the 34-46 range haven't been definitively
 * identified yet. Early devices have either a TriGem Computer, Inc. or a
 * Samsung vendor ID (0x0aa8 and 0x04e8 respectively), while all later
 * devices use the SoundGraph vendor ID (0x15c2). This driver only supports
 * the ffdc and later devices, which do onboard decoding.
 */
static const struct usb_device_id imon_usb_id_table[] = {
        /*
         * Several devices with this same device ID, all use iMON_PAD.inf
         * SoundGraph iMON PAD (IR & VFD)
         * SoundGraph iMON PAD (IR & LCD)
         * SoundGraph iMON Knob (IR only)
         */
        { USB_DEVICE(0x15c2, 0xffdc),
          .driver_info = (unsigned long)&imon_default_table },

        /*
         * Newer devices, all driven by the latest iMON Windows driver, full
         * list of device IDs extracted via 'strings Setup/data1.hdr |grep 15c2'
         * Need user input to fill in details on unknown devices.
         */
        /* SoundGraph iMON OEM Touch LCD (IR & 7" VGA LCD) */
        { USB_DEVICE(0x15c2, 0x0034),
          .driver_info = (unsigned long)&imon_DH102 },
        /* SoundGraph iMON OEM Touch LCD (IR & 4.3" VGA LCD) */
        { USB_DEVICE(0x15c2, 0x0035),
          .driver_info = (unsigned long)&imon_default_table},
        /* SoundGraph iMON OEM VFD (IR & VFD) */
        { USB_DEVICE(0x15c2, 0x0036),
          .driver_info = (unsigned long)&imon_OEM_VFD },
        /* device specifics unknown */
        { USB_DEVICE(0x15c2, 0x0037),
          .driver_info = (unsigned long)&imon_default_table},
        /* SoundGraph iMON OEM LCD (IR & LCD) */
        { USB_DEVICE(0x15c2, 0x0038),
          .driver_info = (unsigned long)&imon_default_table},
        /* SoundGraph iMON UltraBay (IR & LCD) */
        { USB_DEVICE(0x15c2, 0x0039),
          .driver_info = (unsigned long)&imon_default_table},
        /* device specifics unknown */
        { USB_DEVICE(0x15c2, 0x003a),
          .driver_info = (unsigned long)&imon_default_table},
        /* device specifics unknown */
        { USB_DEVICE(0x15c2, 0x003b),
          .driver_info = (unsigned long)&imon_default_table},
        /* SoundGraph iMON OEM Inside (IR only) */
        { USB_DEVICE(0x15c2, 0x003c),
          .driver_info = (unsigned long)&imon_default_table},
        /* device specifics unknown */
        { USB_DEVICE(0x15c2, 0x003d),
          .driver_info = (unsigned long)&imon_default_table},
        /* device specifics unknown */
        { USB_DEVICE(0x15c2, 0x003e),
          .driver_info = (unsigned long)&imon_default_table},
        /* device specifics unknown */
        { USB_DEVICE(0x15c2, 0x003f),
          .driver_info = (unsigned long)&imon_default_table},
        /* device specifics unknown */
        { USB_DEVICE(0x15c2, 0x0040),
          .driver_info = (unsigned long)&imon_default_table},
        /* SoundGraph iMON MINI (IR only) */
        { USB_DEVICE(0x15c2, 0x0041),
          .driver_info = (unsigned long)&imon_default_table},
        /* Antec Veris Multimedia Station EZ External (IR only) */
        { USB_DEVICE(0x15c2, 0x0042),
          .driver_info = (unsigned long)&imon_default_table},
        /* Antec Veris Multimedia Station Basic Internal (IR only) */
        { USB_DEVICE(0x15c2, 0x0043),
          .driver_info = (unsigned long)&imon_default_table},
        /* Antec Veris Multimedia Station Elite (IR & VFD) */
        { USB_DEVICE(0x15c2, 0x0044),
          .driver_info = (unsigned long)&imon_default_table},
        /* Antec Veris Multimedia Station Premiere (IR & LCD) */
        { USB_DEVICE(0x15c2, 0x0045),
          .driver_info = (unsigned long)&imon_default_table},
        /* device specifics unknown */
        { USB_DEVICE(0x15c2, 0x0046),
          .driver_info = (unsigned long)&imon_default_table},
        {}
};

/* USB Device data */
static struct usb_driver imon_driver = {
        .name           = MOD_NAME,
        .probe          = imon_probe,
        .disconnect     = imon_disconnect,
        .suspend        = imon_suspend,
        .resume         = imon_resume,
        .id_table       = imon_usb_id_table,
};

/* to prevent races between open() and disconnect(), probing, etc */
static DEFINE_MUTEX(driver_lock);

/* Module bookkeeping bits */
MODULE_AUTHOR(MOD_AUTHOR);
MODULE_DESCRIPTION(MOD_DESC);
MODULE_VERSION(MOD_VERSION);
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(usb, imon_usb_id_table);

static bool debug;
module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug messages: 0=no, 1=yes (default: no)");

/* lcd, vfd, vga or none? should be auto-detected, but can be overridden... */
static int display_type;
module_param(display_type, int, S_IRUGO);
MODULE_PARM_DESC(display_type, "Type of attached display. 0=autodetect, 1=vfd, 2=lcd, 3=vga, 4=none (default: autodetect)");

static int pad_stabilize = 1;
module_param(pad_stabilize, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(pad_stabilize, "Apply stabilization algorithm to iMON PAD presses in arrow key mode. 0=disable, 1=enable (default).");

/*
 * In certain use cases, mouse mode isn't really helpful, and could actually
 * cause confusion, so allow disabling it when the IR device is open.
 */
static bool nomouse;
module_param(nomouse, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(nomouse, "Disable mouse input device mode when IR device is open. 0=don't disable, 1=disable. (default: don't disable)");

/* threshold at which a pad push registers as an arrow key in kbd mode */
static int pad_thresh;
module_param(pad_thresh, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(pad_thresh, "Threshold at which a pad push registers as an arrow key in kbd mode (default: 28)");


static void free_imon_context(struct imon_context *ictx)
{
        struct device *dev = ictx->dev;

        usb_free_urb(ictx->tx_urb);
        usb_free_urb(ictx->rx_urb_intf0);
        usb_free_urb(ictx->rx_urb_intf1);
        kfree(ictx);

        dev_dbg(dev, "%s: iMON context freed\n", __func__);
}

/*
 * Called when the Display device (e.g. /dev/lcd0)
 * is opened by the application.
 */
static int display_open(struct inode *inode, struct file *file)
{
        struct usb_interface *interface;
        struct imon_context *ictx = NULL;
        int subminor;
        int retval = 0;

        /* prevent races with disconnect */
        mutex_lock(&driver_lock);

        subminor = iminor(inode);
        interface = usb_find_interface(&imon_driver, subminor);
        if (!interface) {
                pr_err("could not find interface for minor %d\n", subminor);
                retval = -ENODEV;
                goto exit;
        }
        ictx = usb_get_intfdata(interface);

        if (!ictx) {
                pr_err("no context found for minor %d\n", subminor);
                retval = -ENODEV;
                goto exit;
        }

        mutex_lock(&ictx->lock);

        if (!ictx->display_supported) {
                pr_err("display not supported by device\n");
                retval = -ENODEV;
        } else if (ictx->display_isopen) {
                pr_err("display port is already open\n");
                retval = -EBUSY;
        } else {
                ictx->display_isopen = true;
                file->private_data = ictx;
                dev_dbg(ictx->dev, "display port opened\n");
        }

        mutex_unlock(&ictx->lock);

exit:
        mutex_unlock(&driver_lock);
        return retval;
}

/*
 * Called when the display device (e.g. /dev/lcd0)
 * is closed by the application.
 */
static int display_close(struct inode *inode, struct file *file)
{
        struct imon_context *ictx = NULL;
        int retval = 0;

        ictx = file->private_data;

        if (!ictx) {
                pr_err("no context for device\n");
                return -ENODEV;
        }

        mutex_lock(&ictx->lock);

        if (!ictx->display_supported) {
                pr_err("display not supported by device\n");
                retval = -ENODEV;
        } else if (!ictx->display_isopen) {
                pr_err("display is not open\n");
                retval = -EIO;
        } else {
                ictx->display_isopen = false;
                dev_dbg(ictx->dev, "display port closed\n");
        }

        mutex_unlock(&ictx->lock);
        return retval;
}

/*
 * Sends a packet to the device -- this function must be called with
 * ictx->lock held, or its unlock/lock sequence while waiting for tx
 * to complete can/will lead to a deadlock.
 */
static int send_packet(struct imon_context *ictx)
{
        unsigned int pipe;
        unsigned long timeout;
        int interval = 0;
        int retval = 0;
        struct usb_ctrlrequest *control_req = NULL;

        /* Check if we need to use control or interrupt urb */
        if (!ictx->tx_control) {
                pipe = usb_sndintpipe(ictx->usbdev_intf0,
                                      ictx->tx_endpoint->bEndpointAddress);
                interval = ictx->tx_endpoint->bInterval;

                usb_fill_int_urb(ictx->tx_urb, ictx->usbdev_intf0, pipe,
                                 ictx->usb_tx_buf,
                                 sizeof(ictx->usb_tx_buf),
                                 usb_tx_callback, ictx, interval);

                ictx->tx_urb->actual_length = 0;
        } else {
                /* fill request into kmalloc'ed space: */
                control_req = kmalloc(sizeof(*control_req), GFP_KERNEL);
                if (control_req == NULL)
                        return -ENOMEM;

                /* setup packet is '21 09 0200 0001 0008' */
                control_req->bRequestType = 0x21;
                control_req->bRequest = 0x09;
                control_req->wValue = cpu_to_le16(0x0200);
                control_req->wIndex = cpu_to_le16(0x0001);
                control_req->wLength = cpu_to_le16(0x0008);

                /* control pipe is endpoint 0x00 */
                pipe = usb_sndctrlpipe(ictx->usbdev_intf0, 0);

                /* build the control urb */
                usb_fill_control_urb(ictx->tx_urb, ictx->usbdev_intf0,
                                     pipe, (unsigned char *)control_req,
                                     ictx->usb_tx_buf,
                                     sizeof(ictx->usb_tx_buf),
                                     usb_tx_callback, ictx);
                ictx->tx_urb->actual_length = 0;
        }

        reinit_completion(&ictx->tx.finished);
        ictx->tx.busy = true;
        smp_rmb(); /* ensure later readers know we're busy */

        retval = usb_submit_urb(ictx->tx_urb, GFP_KERNEL);
        if (retval) {
                ictx->tx.busy = false;
                smp_rmb(); /* ensure later readers know we're not busy */
                pr_err_ratelimited("error submitting urb(%d)\n", retval);
        } else {
                /* Wait for transmission to complete (or abort) */
                mutex_unlock(&ictx->lock);
                retval = wait_for_completion_interruptible(
                                &ictx->tx.finished);
                if (retval) {
                        usb_kill_urb(ictx->tx_urb);
                        pr_err_ratelimited("task interrupted\n");
                }
                mutex_lock(&ictx->lock);

                retval = ictx->tx.status;
                if (retval)
                        pr_err_ratelimited("packet tx failed (%d)\n", retval);
        }

        kfree(control_req);

        /*
         * Induce a mandatory delay before returning, as otherwise,
         * send_packet can get called so rapidly as to overwhelm the device,
         * particularly on faster systems and/or those with quirky usb.
         */
        timeout = msecs_to_jiffies(ictx->send_packet_delay);
        set_current_state(TASK_INTERRUPTIBLE);
        schedule_timeout(timeout);

        return retval;
}

/*
 * Sends an associate packet to the iMON 2.4G.
 *
 * This might not be such a good idea, since it has an id collision with
 * some versions of the "IR & VFD" combo. The only way to determine if it
 * is an RF version is to look at the product description string. (Which
 * we currently do not fetch).
 */
static int send_associate_24g(struct imon_context *ictx)
{
        int retval;
        const unsigned char packet[8] = { 0x01, 0x00, 0x00, 0x00,
                                          0x00, 0x00, 0x00, 0x20 };

        if (!ictx) {
                pr_err("no context for device\n");
                return -ENODEV;
        }

        if (!ictx->dev_present_intf0) {
                pr_err("no iMON device present\n");
                return -ENODEV;
        }

        memcpy(ictx->usb_tx_buf, packet, sizeof(packet));
        retval = send_packet(ictx);

        return retval;
}

/*
 * Sends packets to setup and show clock on iMON display
 *
 * Arguments: year - last 2 digits of year, month - 1..12,
 * day - 1..31, dow - day of the week (0-Sun...6-Sat),
 * hour - 0..23, minute - 0..59, second - 0..59
 */
static int send_set_imon_clock(struct imon_context *ictx,
                               unsigned int year, unsigned int month,
                               unsigned int day, unsigned int dow,
                               unsigned int hour, unsigned int minute,
                               unsigned int second)
{
        unsigned char clock_enable_pkt[IMON_CLOCK_ENABLE_PACKETS][8];
        int retval = 0;
        int i;

        if (!ictx) {
                pr_err("no context for device\n");
                return -ENODEV;
        }

        switch (ictx->display_type) {
        case IMON_DISPLAY_TYPE_LCD:
                clock_enable_pkt[0][0] = 0x80;
                clock_enable_pkt[0][1] = year;
                clock_enable_pkt[0][2] = month-1;
                clock_enable_pkt[0][3] = day;
                clock_enable_pkt[0][4] = hour;
                clock_enable_pkt[0][5] = minute;
                clock_enable_pkt[0][6] = second;

                clock_enable_pkt[1][0] = 0x80;
                clock_enable_pkt[1][1] = 0;
                clock_enable_pkt[1][2] = 0;
                clock_enable_pkt[1][3] = 0;
                clock_enable_pkt[1][4] = 0;
                clock_enable_pkt[1][5] = 0;
                clock_enable_pkt[1][6] = 0;

                if (ictx->product == 0xffdc) {
                        clock_enable_pkt[0][7] = 0x50;
                        clock_enable_pkt[1][7] = 0x51;
                } else {
                        clock_enable_pkt[0][7] = 0x88;
                        clock_enable_pkt[1][7] = 0x8a;
                }

                break;

        case IMON_DISPLAY_TYPE_VFD:
                clock_enable_pkt[0][0] = year;
                clock_enable_pkt[0][1] = month-1;
                clock_enable_pkt[0][2] = day;
                clock_enable_pkt[0][3] = dow;
                clock_enable_pkt[0][4] = hour;
                clock_enable_pkt[0][5] = minute;
                clock_enable_pkt[0][6] = second;
                clock_enable_pkt[0][7] = 0x40;

                clock_enable_pkt[1][0] = 0;
                clock_enable_pkt[1][1] = 0;
                clock_enable_pkt[1][2] = 1;
                clock_enable_pkt[1][3] = 0;
                clock_enable_pkt[1][4] = 0;
                clock_enable_pkt[1][5] = 0;
                clock_enable_pkt[1][6] = 0;
                clock_enable_pkt[1][7] = 0x42;

                break;

        default:
                return -ENODEV;
        }

        for (i = 0; i < IMON_CLOCK_ENABLE_PACKETS; i++) {
                memcpy(ictx->usb_tx_buf, clock_enable_pkt[i], 8);
                retval = send_packet(ictx);
                if (retval) {
                        pr_err("send_packet failed for packet %d\n", i);
                        break;
                }
        }

        return retval;
}

/*
 * These are the sysfs functions to handle the association on the iMON 2.4G LT.
 */
static ssize_t show_associate_remote(struct device *d,
                                     struct device_attribute *attr,
                                     char *buf)
{
        struct imon_context *ictx = dev_get_drvdata(d);

        if (!ictx)
                return -ENODEV;

        mutex_lock(&ictx->lock);
        if (ictx->rf_isassociating)
                strscpy(buf, "associating\n", PAGE_SIZE);
        else
                strscpy(buf, "closed\n", PAGE_SIZE);

        dev_info(d, "Visit http://www.lirc.org/html/imon-24g.html for instructions on how to associate your iMON 2.4G DT/LT remote\n");
        mutex_unlock(&ictx->lock);
        return strlen(buf);
}

static ssize_t store_associate_remote(struct device *d,
                                      struct device_attribute *attr,
                                      const char *buf, size_t count)
{
        struct imon_context *ictx;

        ictx = dev_get_drvdata(d);

        if (!ictx)
                return -ENODEV;

        mutex_lock(&ictx->lock);
        ictx->rf_isassociating = true;
        send_associate_24g(ictx);
        mutex_unlock(&ictx->lock);

        return count;
}

/*
 * sysfs functions to control internal imon clock
 */
static ssize_t show_imon_clock(struct device *d,
                               struct device_attribute *attr, char *buf)
{
        struct imon_context *ictx = dev_get_drvdata(d);
        size_t len;

        if (!ictx)
                return -ENODEV;

        mutex_lock(&ictx->lock);

        if (!ictx->display_supported) {
                len = snprintf(buf, PAGE_SIZE, "Not supported.");
        } else {
                len = snprintf(buf, PAGE_SIZE,
                        "To set the clock on your iMON display:\n"
                        "# date \"+%%y %%m %%d %%w %%H %%M %%S\" > imon_clock\n"
                        "%s", ictx->display_isopen ?
                        "\nNOTE: imon device must be closed\n" : "");
        }

        mutex_unlock(&ictx->lock);

        return len;
}

static ssize_t store_imon_clock(struct device *d,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct imon_context *ictx = dev_get_drvdata(d);
        ssize_t retval;
        unsigned int year, month, day, dow, hour, minute, second;

        if (!ictx)
                return -ENODEV;

        mutex_lock(&ictx->lock);

        if (!ictx->display_supported) {
                retval = -ENODEV;
                goto exit;
        } else if (ictx->display_isopen) {
                retval = -EBUSY;
                goto exit;
        }

        if (sscanf(buf, "%u %u %u %u %u %u %u", &year, &month, &day, &dow,
                   &hour, &minute, &second) != 7) {
                retval = -EINVAL;
                goto exit;
        }

        if ((month < 1 || month > 12) ||
            (day < 1 || day > 31) || (dow > 6) ||
            (hour > 23) || (minute > 59) || (second > 59)) {
                retval = -EINVAL;
                goto exit;
        }

        retval = send_set_imon_clock(ictx, year, month, day, dow,
                                     hour, minute, second);
        if (retval)
                goto exit;

        retval = count;
exit:
        mutex_unlock(&ictx->lock);

        return retval;
}


static DEVICE_ATTR(imon_clock, S_IWUSR | S_IRUGO, show_imon_clock,
                   store_imon_clock);

static DEVICE_ATTR(associate_remote, S_IWUSR | S_IRUGO, show_associate_remote,
                   store_associate_remote);

static struct attribute *imon_display_sysfs_entries[] = {
        &dev_attr_imon_clock.attr,
        NULL
};

static const struct attribute_group imon_display_attr_group = {
        .attrs = imon_display_sysfs_entries
};

static struct attribute *imon_rf_sysfs_entries[] = {
        &dev_attr_associate_remote.attr,
        NULL
};

static const struct attribute_group imon_rf_attr_group = {
        .attrs = imon_rf_sysfs_entries
};

/*
 * Writes data to the VFD.  The iMON VFD is 2x16 characters
 * and requires data in 5 consecutive USB interrupt packets,
 * each packet but the last carrying 7 bytes.
 *
 * I don't know if the VFD board supports features such as
 * scrolling, clearing rows, blanking, etc. so at
 * the caller must provide a full screen of data.  If fewer
 * than 32 bytes are provided spaces will be appended to
 * generate a full screen.
 */
static ssize_t vfd_write(struct file *file, const char __user *buf,
                         size_t n_bytes, loff_t *pos)
{
        int i;
        int offset;
        int seq;
        int retval = 0;
        struct imon_context *ictx;
        static const unsigned char vfd_packet6[] = {
                0x01, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF };

        ictx = file->private_data;
        if (!ictx) {
                pr_err_ratelimited("no context for device\n");
                return -ENODEV;
        }

        mutex_lock(&ictx->lock);

        if (!ictx->dev_present_intf0) {
                pr_err_ratelimited("no iMON device present\n");
                retval = -ENODEV;
                goto exit;
        }

        if (n_bytes <= 0 || n_bytes > 32) {
                pr_err_ratelimited("invalid payload size\n");
                retval = -EINVAL;
                goto exit;
        }

        if (copy_from_user(ictx->tx.data_buf, buf, n_bytes)) {
                retval = -EFAULT;
                goto exit;
        }

        /* Pad with spaces */
        for (i = n_bytes; i < 32; ++i)
                ictx->tx.data_buf[i] = ' ';

        for (i = 32; i < 35; ++i)
                ictx->tx.data_buf[i] = 0xFF;

        offset = 0;
        seq = 0;

        do {
                memcpy(ictx->usb_tx_buf, ictx->tx.data_buf + offset, 7);
                ictx->usb_tx_buf[7] = (unsigned char) seq;

                retval = send_packet(ictx);
                if (retval) {
                        pr_err_ratelimited("send packet #%d failed\n", seq / 2);
                        goto exit;
                } else {
                        seq += 2;
                        offset += 7;
                }

        } while (offset < 35);

        /* Send packet #6 */
        memcpy(ictx->usb_tx_buf, &vfd_packet6, sizeof(vfd_packet6));
        ictx->usb_tx_buf[7] = (unsigned char) seq;
        retval = send_packet(ictx);
        if (retval)
                pr_err_ratelimited("send packet #%d failed\n", seq / 2);

exit:
        mutex_unlock(&ictx->lock);

        return (!retval) ? n_bytes : retval;
}

/*
 * Writes data to the LCD.  The iMON OEM LCD screen expects 8-byte
 * packets. We accept data as 16 hexadecimal digits, followed by a
 * newline (to make it easy to drive the device from a command-line
 * -- even though the actual binary data is a bit complicated).
 *
 * The device itself is not a "traditional" text-mode display. It's
 * actually a 16x96 pixel bitmap display. That means if you want to
 * display text, you've got to have your own "font" and translate the
 * text into bitmaps for display. This is really flexible (you can
 * display whatever diacritics you need, and so on), but it's also
 * a lot more complicated than most LCDs...
 */

static ssize_t lcd_write(struct file *file, const char __user *buf,
                         size_t n_bytes, loff_t *pos)
{
        int retval = 0;
        struct imon_context *ictx;

        ictx = file->private_data;
        if (!ictx) {
                pr_err_ratelimited("no context for device\n");
                return -ENODEV;
        }

        mutex_lock(&ictx->lock);

        if (!ictx->display_supported) {
                pr_err_ratelimited("no iMON display present\n");
                retval = -ENODEV;
                goto exit;
        }

        if (n_bytes != 8) {
                pr_err_ratelimited("invalid payload size: %d (expected 8)\n",
                                   (int)n_bytes);
                retval = -EINVAL;
                goto exit;
        }

        if (copy_from_user(ictx->usb_tx_buf, buf, 8)) {
                retval = -EFAULT;
                goto exit;
        }

        retval = send_packet(ictx);
        if (retval) {
                pr_err_ratelimited("send packet failed!\n");
                goto exit;
        } else {
                dev_dbg(ictx->dev, "%s: write %d bytes to LCD\n",
                        __func__, (int) n_bytes);
        }
exit:
        mutex_unlock(&ictx->lock);
        return (!retval) ? n_bytes : retval;
}

/*
 * Callback function for USB core API: transmit data
 */
static void usb_tx_callback(struct urb *urb)
{
        struct imon_context *ictx;

        if (!urb)
                return;
        ictx = (struct imon_context *)urb->context;
        if (!ictx)
                return;

        ictx->tx.status = urb->status;

        /* notify waiters that write has finished */
        ictx->tx.busy = false;
        smp_rmb(); /* ensure later readers know we're not busy */
        complete(&ictx->tx.finished);
}

/*
 * report touchscreen input
 */
static void imon_touch_display_timeout(struct timer_list *t)
{
        struct imon_context *ictx = from_timer(ictx, t, ttimer);

        if (ictx->display_type != IMON_DISPLAY_TYPE_VGA)
                return;

        input_report_abs(ictx->touch, ABS_X, ictx->touch_x);
        input_report_abs(ictx->touch, ABS_Y, ictx->touch_y);
        input_report_key(ictx->touch, BTN_TOUCH, 0x00);
        input_sync(ictx->touch);
}

/*
 * iMON IR receivers support two different signal sets -- those used by
 * the iMON remotes, and those used by the Windows MCE remotes (which is
 * really just RC-6), but only one or the other at a time, as the signals
 * are decoded onboard the receiver.
 *
 * This function gets called two different ways, one way is from
 * rc_register_device, for initial protocol selection/setup, and the other is
 * via a userspace-initiated protocol change request, either by direct sysfs
 * prodding or by something like ir-keytable. In the rc_register_device case,
 * the imon context lock is already held, but when initiated from userspace,
 * it is not, so we must acquire it prior to calling send_packet, which
 * requires that the lock is held.
 */
static int imon_ir_change_protocol(struct rc_dev *rc, u64 *rc_proto)
{
        int retval;
        struct imon_context *ictx = rc->priv;
        struct device *dev = ictx->dev;
        bool unlock = false;
        unsigned char ir_proto_packet[] = {
                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x86 };

        if (*rc_proto && !(*rc_proto & rc->allowed_protocols))
                dev_warn(dev, "Looks like you're trying to use an IR protocol this device does not support\n");

        if (*rc_proto & RC_PROTO_BIT_RC6_MCE) {
                dev_dbg(dev, "Configuring IR receiver for MCE protocol\n");
                ir_proto_packet[0] = 0x01;
                *rc_proto = RC_PROTO_BIT_RC6_MCE;
        } else if (*rc_proto & RC_PROTO_BIT_IMON) {
                dev_dbg(dev, "Configuring IR receiver for iMON protocol\n");
                if (!pad_stabilize)
                        dev_dbg(dev, "PAD stabilize functionality disabled\n");
                /* ir_proto_packet[0] = 0x00; // already the default */
                *rc_proto = RC_PROTO_BIT_IMON;
        } else {
                dev_warn(dev, "Unsupported IR protocol specified, overriding to iMON IR protocol\n");
                if (!pad_stabilize)
                        dev_dbg(dev, "PAD stabilize functionality disabled\n");
                /* ir_proto_packet[0] = 0x00; // already the default */
                *rc_proto = RC_PROTO_BIT_IMON;
        }

        memcpy(ictx->usb_tx_buf, &ir_proto_packet, sizeof(ir_proto_packet));

        if (!mutex_is_locked(&ictx->lock)) {
                unlock = true;
                mutex_lock(&ictx->lock);
        }

        retval = send_packet(ictx);
        if (retval)
                goto out;

        ictx->rc_proto = *rc_proto;
        ictx->pad_mouse = false;

out:
        if (unlock)
                mutex_unlock(&ictx->lock);

        return retval;
}

/*
 * The directional pad behaves a bit differently, depending on whether this is
 * one of the older ffdc devices or a newer device. Newer devices appear to
 * have a higher resolution matrix for more precise mouse movement, but it
 * makes things overly sensitive in keyboard mode, so we do some interesting
 * contortions to make it less touchy. Older devices run through the same
 * routine with shorter timeout and a smaller threshold.
 */
static int stabilize(int a, int b, u16 timeout, u16 threshold)
{
        ktime_t ct;
        static ktime_t prev_time;
        static ktime_t hit_time;
        static int x, y, prev_result, hits;
        int result = 0;
        long msec, msec_hit;

        ct = ktime_get();
        msec = ktime_ms_delta(ct, prev_time);
        msec_hit = ktime_ms_delta(ct, hit_time);

        if (msec > 100) {
                x = 0;
                y = 0;
                hits = 0;
        }

        x += a;
        y += b;

        prev_time = ct;

        if (abs(x) > threshold || abs(y) > threshold) {
                if (abs(y) > abs(x))
                        result = (y > 0) ? 0x7F : 0x80;
                else
                        result = (x > 0) ? 0x7F00 : 0x8000;

                x = 0;
                y = 0;

                if (result == prev_result) {
                        hits++;

                        if (hits > 3) {
                                switch (result) {
                                case 0x7F:
                                        y = 17 * threshold / 30;
                                        break;
                                case 0x80:
                                        y -= 17 * threshold / 30;
                                        break;
                                case 0x7F00:
                                        x = 17 * threshold / 30;
                                        break;
                                case 0x8000:
                                        x -= 17 * threshold / 30;
                                        break;
                                }
                        }

                        if (hits == 2 && msec_hit < timeout) {
                                result = 0;
                                hits = 1;
                        }
                } else {
                        prev_result = result;
                        hits = 1;
                        hit_time = ct;
                }
        }

        return result;
}

static u32 imon_remote_key_lookup(struct imon_context *ictx, u32 scancode)
{
        u32 keycode;
        u32 release;
        bool is_release_code = false;

        /* Look for the initial press of a button */
        keycode = rc_g_keycode_from_table(ictx->rdev, scancode);
        ictx->rc_toggle = 0x0;
        ictx->rc_scancode = scancode;

        /* Look for the release of a button */
        if (keycode == KEY_RESERVED) {
                release = scancode & ~0x4000;
                keycode = rc_g_keycode_from_table(ictx->rdev, release);
                if (keycode != KEY_RESERVED)
                        is_release_code = true;
        }

        ictx->release_code = is_release_code;

        return keycode;
}

static u32 imon_mce_key_lookup(struct imon_context *ictx, u32 scancode)
{
        u32 keycode;

#define MCE_KEY_MASK 0x7000
#define MCE_TOGGLE_BIT 0x8000

        /*
         * On some receivers, mce keys decode to 0x8000f04xx and 0x8000f84xx
         * (the toggle bit flipping between alternating key presses), while
         * on other receivers, we see 0x8000f74xx and 0x8000ff4xx. To keep
         * the table trim, we always or in the bits to look up 0x8000ff4xx,
         * but we can't or them into all codes, as some keys are decoded in
         * a different way w/o the same use of the toggle bit...
         */
        if (scancode & 0x80000000)
                scancode = scancode | MCE_KEY_MASK | MCE_TOGGLE_BIT;

        ictx->rc_scancode = scancode;
        keycode = rc_g_keycode_from_table(ictx->rdev, scancode);

        /* not used in mce mode, but make sure we know its false */
        ictx->release_code = false;

        return keycode;
}

static u32 imon_panel_key_lookup(struct imon_context *ictx, u64 code)
{
        int i;
        u32 keycode = KEY_RESERVED;
        struct imon_panel_key_table *key_table = ictx->dev_descr->key_table;

        for (i = 0; key_table[i].hw_code != 0; i++) {
                if (key_table[i].hw_code == (code | 0xffee)) {
                        keycode = key_table[i].keycode;
                        break;
                }
        }
        ictx->release_code = false;
        return keycode;
}

static bool imon_mouse_event(struct imon_context *ictx,
                             unsigned char *buf, int len)
{
        signed char rel_x = 0x00, rel_y = 0x00;
        u8 right_shift = 1;
        bool mouse_input = true;
        int dir = 0;
        unsigned long flags;

        spin_lock_irqsave(&ictx->kc_lock, flags);

        /* newer iMON device PAD or mouse button */
        if (ictx->product != 0xffdc && (buf[0] & 0x01) && len == 5) {
                rel_x = buf[2];
                rel_y = buf[3];
                right_shift = 1;
        /* 0xffdc iMON PAD or mouse button input */
        } else if (ictx->product == 0xffdc && (buf[0] & 0x40) &&
                        !((buf[1] & 0x01) || ((buf[1] >> 2) & 0x01))) {
                rel_x = (buf[1] & 0x08) | (buf[1] & 0x10) >> 2 |
                        (buf[1] & 0x20) >> 4 | (buf[1] & 0x40) >> 6;
                if (buf[0] & 0x02)
                        rel_x |= ~0x0f;
                rel_x = rel_x + rel_x / 2;
                rel_y = (buf[2] & 0x08) | (buf[2] & 0x10) >> 2 |
                        (buf[2] & 0x20) >> 4 | (buf[2] & 0x40) >> 6;
                if (buf[0] & 0x01)
                        rel_y |= ~0x0f;
                rel_y = rel_y + rel_y / 2;
                right_shift = 2;
        /* some ffdc devices decode mouse buttons differently... */
        } else if (ictx->product == 0xffdc && (buf[0] == 0x68)) {
                right_shift = 2;
        /* ch+/- buttons, which we use for an emulated scroll wheel */
        } else if (ictx->kc == KEY_CHANNELUP && (buf[2] & 0x40) != 0x40) {
                dir = 1;
        } else if (ictx->kc == KEY_CHANNELDOWN && (buf[2] & 0x40) != 0x40) {
                dir = -1;
        } else
                mouse_input = false;

        spin_unlock_irqrestore(&ictx->kc_lock, flags);

        if (mouse_input) {
                dev_dbg(ictx->dev, "sending mouse data via input subsystem\n");

                if (dir) {
                        input_report_rel(ictx->idev, REL_WHEEL, dir);
                } else if (rel_x || rel_y) {
                        input_report_rel(ictx->idev, REL_X, rel_x);
                        input_report_rel(ictx->idev, REL_Y, rel_y);
                } else {
                        input_report_key(ictx->idev, BTN_LEFT, buf[1] & 0x1);
                        input_report_key(ictx->idev, BTN_RIGHT,
                                         buf[1] >> right_shift & 0x1);
                }
                input_sync(ictx->idev);
                spin_lock_irqsave(&ictx->kc_lock, flags);
                ictx->last_keycode = ictx->kc;
                spin_unlock_irqrestore(&ictx->kc_lock, flags);
        }

        return mouse_input;
}

static void imon_touch_event(struct imon_context *ictx, unsigned char *buf)
{
        mod_timer(&ictx->ttimer, jiffies + TOUCH_TIMEOUT);
        ictx->touch_x = (buf[0] << 4) | (buf[1] >> 4);
        ictx->touch_y = 0xfff - ((buf[2] << 4) | (buf[1] & 0xf));
        input_report_abs(ictx->touch, ABS_X, ictx->touch_x);
        input_report_abs(ictx->touch, ABS_Y, ictx->touch_y);
        input_report_key(ictx->touch, BTN_TOUCH, 0x01);
        input_sync(ictx->touch);
}

static void imon_pad_to_keys(struct imon_context *ictx, unsigned char *buf)
{
        int dir = 0;
        signed char rel_x = 0x00, rel_y = 0x00;
        u16 timeout, threshold;
        u32 scancode = KEY_RESERVED;
        unsigned long flags;

        /*
         * The imon directional pad functions more like a touchpad. Bytes 3 & 4
         * contain a position coordinate (x,y), with each component ranging
         * from -14 to 14. We want to down-sample this to only 4 discrete values
         * for up/down/left/right arrow keys. Also, when you get too close to
         * diagonals, it has a tendency to jump back and forth, so lets try to
         * ignore when they get too close.
         */
        if (ictx->product != 0xffdc) {
                /* first, pad to 8 bytes so it conforms with everything else */
                buf[5] = buf[6] = buf[7] = 0;
                timeout = 500;  /* in msecs */
                /* (2*threshold) x (2*threshold) square */
                threshold = pad_thresh ? pad_thresh : 28;
                rel_x = buf[2];
                rel_y = buf[3];

                if (ictx->rc_proto == RC_PROTO_BIT_IMON && pad_stabilize) {
                        if ((buf[1] == 0) && ((rel_x != 0) || (rel_y != 0))) {
                                dir = stabilize((int)rel_x, (int)rel_y,
                                                timeout, threshold);
                                if (!dir) {
                                        spin_lock_irqsave(&ictx->kc_lock,
                                                          flags);
                                        ictx->kc = KEY_UNKNOWN;
                                        spin_unlock_irqrestore(&ictx->kc_lock,
                                                               flags);
                                        return;
                                }
                                buf[2] = dir & 0xFF;
                                buf[3] = (dir >> 8) & 0xFF;
                                scancode = be32_to_cpu(*((__be32 *)buf));
                        }
                } else {
                        /*
                         * Hack alert: instead of using keycodes, we have
                         * to use hard-coded scancodes here...
                         */
                        if (abs(rel_y) > abs(rel_x)) {
                                buf[2] = (rel_y > 0) ? 0x7F : 0x80;
                                buf[3] = 0;
                                if (rel_y > 0)
                                        scancode = 0x01007f00; /* KEY_DOWN */
                                else
                                        scancode = 0x01008000; /* KEY_UP */
                        } else {
                                buf[2] = 0;
                                buf[3] = (rel_x > 0) ? 0x7F : 0x80;
                                if (rel_x > 0)
                                        scancode = 0x0100007f; /* KEY_RIGHT */
                                else
                                        scancode = 0x01000080; /* KEY_LEFT */
                        }
                }

        /*
         * Handle on-board decoded pad events for e.g. older VFD/iMON-Pad
         * device (15c2:ffdc). The remote generates various codes from
         * 0x68nnnnB7 to 0x6AnnnnB7, the left mouse button generates
         * 0x688301b7 and the right one 0x688481b7. All other keys generate
         * 0x2nnnnnnn. Position coordinate is encoded in buf[1] and buf[2] with
         * reversed endianness. Extract direction from buffer, rotate endianness,
         * adjust sign and feed the values into stabilize(). The resulting codes
         * will be 0x01008000, 0x01007F00, which match the newer devices.
         */
        } else {
                timeout = 10;   /* in msecs */
                /* (2*threshold) x (2*threshold) square */
                threshold = pad_thresh ? pad_thresh : 15;

                /* buf[1] is x */
                rel_x = (buf[1] & 0x08) | (buf[1] & 0x10) >> 2 |
                        (buf[1] & 0x20) >> 4 | (buf[1] & 0x40) >> 6;
                if (buf[0] & 0x02)
                        rel_x |= ~0x10+1;
                /* buf[2] is y */
                rel_y = (buf[2] & 0x08) | (buf[2] & 0x10) >> 2 |
                        (buf[2] & 0x20) >> 4 | (buf[2] & 0x40) >> 6;
                if (buf[0] & 0x01)
                        rel_y |= ~0x10+1;

                buf[0] = 0x01;
                buf[1] = buf[4] = buf[5] = buf[6] = buf[7] = 0;

                if (ictx->rc_proto == RC_PROTO_BIT_IMON && pad_stabilize) {
                        dir = stabilize((int)rel_x, (int)rel_y,
                                        timeout, threshold);
                        if (!dir) {
                                spin_lock_irqsave(&ictx->kc_lock, flags);
                                ictx->kc = KEY_UNKNOWN;
                                spin_unlock_irqrestore(&ictx->kc_lock, flags);
                                return;
                        }
                        buf[2] = dir & 0xFF;
                        buf[3] = (dir >> 8) & 0xFF;
                        scancode = be32_to_cpu(*((__be32 *)buf));
                } else {
                        /*
                         * Hack alert: instead of using keycodes, we have
                         * to use hard-coded scancodes here...
                         */
                        if (abs(rel_y) > abs(rel_x)) {
                                buf[2] = (rel_y > 0) ? 0x7F : 0x80;
                                buf[3] = 0;
                                if (rel_y > 0)
                                        scancode = 0x01007f00; /* KEY_DOWN */
                                else
                                        scancode = 0x01008000; /* KEY_UP */
                        } else {
                                buf[2] = 0;
                                buf[3] = (rel_x > 0) ? 0x7F : 0x80;
                                if (rel_x > 0)
                                        scancode = 0x0100007f; /* KEY_RIGHT */
                                else
                                        scancode = 0x01000080; /* KEY_LEFT */
                        }
                }
        }

        if (scancode) {
                spin_lock_irqsave(&ictx->kc_lock, flags);
                ictx->kc = imon_remote_key_lookup(ictx, scancode);
                spin_unlock_irqrestore(&ictx->kc_lock, flags);
        }
}

/*
 * figure out if these is a press or a release. We don't actually
 * care about repeats, as those will be auto-generated within the IR
 * subsystem for repeating scancodes.
 */
static int imon_parse_press_type(struct imon_context *ictx,
                                 unsigned char *buf, u8 ktype)
{
        int press_type = 0;
        unsigned long flags;

        spin_lock_irqsave(&ictx->kc_lock, flags);

        /* key release of 0x02XXXXXX key */
        if (ictx->kc == KEY_RESERVED && buf[0] == 0x02 && buf[3] == 0x00)
                ictx->kc = ictx->last_keycode;

        /* mouse button release on (some) 0xffdc devices */
        else if (ictx->kc == KEY_RESERVED && buf[0] == 0x68 && buf[1] == 0x82 &&
                 buf[2] == 0x81 && buf[3] == 0xb7)
                ictx->kc = ictx->last_keycode;

        /* mouse button release on (some other) 0xffdc devices */
        else if (ictx->kc == KEY_RESERVED && buf[0] == 0x01 && buf[1] == 0x00 &&
                 buf[2] == 0x81 && buf[3] == 0xb7)
                ictx->kc = ictx->last_keycode;

        /* mce-specific button handling, no keyup events */
        else if (ktype == IMON_KEY_MCE) {
                ictx->rc_toggle = buf[2];
                press_type = 1;

        /* incoherent or irrelevant data */
        } else if (ictx->kc == KEY_RESERVED)
                press_type = -EINVAL;

        /* key release of 0xXXXXXXb7 key */
        else if (ictx->release_code)
                press_type = 0;

        /* this is a button press */
        else
                press_type = 1;

        spin_unlock_irqrestore(&ictx->kc_lock, flags);

        return press_type;
}

/*
 * Process the incoming packet
 */
static void imon_incoming_packet(struct imon_context *ictx,
                                 struct urb *urb, int intf)
{
        int len = urb->actual_length;
        unsigned char *buf = urb->transfer_buffer;
        struct device *dev = ictx->dev;
        unsigned long flags;
        u32 kc;
        u64 scancode;
        int press_type = 0;
        long msec;
        ktime_t t;
        static ktime_t prev_time;
        u8 ktype;

        /* filter out junk data on the older 0xffdc imon devices */
        if ((buf[0] == 0xff) && (buf[1] == 0xff) && (buf[2] == 0xff))
                return;

        /* Figure out what key was pressed */
        if (len == 8 && buf[7] == 0xee) {
                scancode = be64_to_cpu(*((__be64 *)buf));
                ktype = IMON_KEY_PANEL;
                kc = imon_panel_key_lookup(ictx, scancode);
                ictx->release_code = false;
        } else {
                scancode = be32_to_cpu(*((__be32 *)buf));
                if (ictx->rc_proto == RC_PROTO_BIT_RC6_MCE) {
                        ktype = IMON_KEY_IMON;
                        if (buf[0] == 0x80)
                                ktype = IMON_KEY_MCE;
                        kc = imon_mce_key_lookup(ictx, scancode);
                } else {
                        ktype = IMON_KEY_IMON;
                        kc = imon_remote_key_lookup(ictx, scancode);
                }
        }

        spin_lock_irqsave(&ictx->kc_lock, flags);
        /* keyboard/mouse mode toggle button */
        if (kc == KEY_KEYBOARD && !ictx->release_code) {
                ictx->last_keycode = kc;
                if (!nomouse) {
                        ictx->pad_mouse = !ictx->pad_mouse;
                        dev_dbg(dev, "toggling to %s mode\n",
                                ictx->pad_mouse ? "mouse" : "keyboard");
                        spin_unlock_irqrestore(&ictx->kc_lock, flags);
                        return;
                } else {
                        ictx->pad_mouse = false;
                        dev_dbg(dev, "mouse mode disabled, passing key value\n");
                }
        }

        ictx->kc = kc;
        spin_unlock_irqrestore(&ictx->kc_lock, flags);

        /* send touchscreen events through input subsystem if touchpad data */
        if (ictx->display_type == IMON_DISPLAY_TYPE_VGA && len == 8 &&
            buf[7] == 0x86) {
                imon_touch_event(ictx, buf);
                return;

        /* look for mouse events with pad in mouse mode */
        } else if (ictx->pad_mouse) {
                if (imon_mouse_event(ictx, buf, len))
                        return;
        }

        /* Now for some special handling to convert pad input to arrow keys */
        if (((len == 5) && (buf[0] == 0x01) && (buf[4] == 0x00)) ||
            ((len == 8) && (buf[0] & 0x40) &&
             !(buf[1] & 0x1 || buf[1] >> 2 & 0x1))) {
                len = 8;
                imon_pad_to_keys(ictx, buf);
        }

        if (debug) {
                printk(KERN_INFO "intf%d decoded packet: %*ph\n",
                       intf, len, buf);
        }

        press_type = imon_parse_press_type(ictx, buf, ktype);
        if (press_type < 0)
                goto not_input_data;

        if (ktype != IMON_KEY_PANEL) {
                if (press_type == 0)
                        rc_keyup(ictx->rdev);
                else {
                        enum rc_proto proto;

                        if (ictx->rc_proto == RC_PROTO_BIT_RC6_MCE)
                                proto = RC_PROTO_RC6_MCE;
                        else if (ictx->rc_proto == RC_PROTO_BIT_IMON)
                                proto = RC_PROTO_IMON;
                        else
                                return;

                        rc_keydown(ictx->rdev, proto, ictx->rc_scancode,
                                   ictx->rc_toggle);

                        spin_lock_irqsave(&ictx->kc_lock, flags);
                        ictx->last_keycode = ictx->kc;
                        spin_unlock_irqrestore(&ictx->kc_lock, flags);
                }
                return;
        }

        /* Only panel type events left to process now */
        spin_lock_irqsave(&ictx->kc_lock, flags);

        t = ktime_get();
        /* KEY_MUTE repeats from knob need to be suppressed */
        if (ictx->kc == KEY_MUTE && ictx->kc == ictx->last_keycode) {
                msec = ktime_ms_delta(t, prev_time);
                if (msec < ictx->idev->rep[REP_DELAY]) {
                        spin_unlock_irqrestore(&ictx->kc_lock, flags);
                        return;
                }
        }
        prev_time = t;
        kc = ictx->kc;

        spin_unlock_irqrestore(&ictx->kc_lock, flags);

        input_report_key(ictx->idev, kc, press_type);
        input_sync(ictx->idev);

        /* panel keys don't generate a release */
        input_report_key(ictx->idev, kc, 0);
        input_sync(ictx->idev);

        spin_lock_irqsave(&ictx->kc_lock, flags);
        ictx->last_keycode = kc;
        spin_unlock_irqrestore(&ictx->kc_lock, flags);

        return;

not_input_data:
        if (len != 8) {
                dev_warn(dev, "imon %s: invalid incoming packet size (len = %d, intf%d)\n",
                         __func__, len, intf);
                return;
        }

        /* iMON 2.4G associate frame */
        if (buf[0] == 0x00 &&
            buf[2] == 0xFF &&                           /* REFID */
            buf[3] == 0xFF &&
            buf[4] == 0xFF &&
            buf[5] == 0xFF &&                           /* iMON 2.4G */
           ((buf[6] == 0x4E && buf[7] == 0xDF) ||       /* LT */
            (buf[6] == 0x5E && buf[7] == 0xDF))) {      /* DT */
                dev_warn(dev, "%s: remote associated refid=%02X\n",
                         __func__, buf[1]);
                ictx->rf_isassociating = false;
        }
}

/*
 * Callback function for USB core API: receive data
 */
static void usb_rx_callback_intf0(struct urb *urb)
{
        struct imon_context *ictx;
        int intfnum = 0;

        if (!urb)
                return;

        ictx = (struct imon_context *)urb->context;
        if (!ictx)
                return;

        /*
         * if we get a callback before we're done configuring the hardware, we
         * can't yet process the data, as there's nowhere to send it, but we
         * still need to submit a new rx URB to avoid wedging the hardware
         */
        if (!ictx->dev_present_intf0)
                goto out;

        switch (urb->status) {
        case -ENOENT:           /* usbcore unlink successful! */
                return;

        case -ESHUTDOWN:        /* transport endpoint was shut down */
                break;

        case 0:
                imon_incoming_packet(ictx, urb, intfnum);
                break;

        default:
                dev_warn(ictx->dev, "imon %s: status(%d): ignored\n",
                         __func__, urb->status);
                break;
        }

out:
        usb_submit_urb(ictx->rx_urb_intf0, GFP_ATOMIC);
}

static void usb_rx_callback_intf1(struct urb *urb)
{
        struct imon_context *ictx;
        int intfnum = 1;

        if (!urb)
                return;

        ictx = (struct imon_context *)urb->context;
        if (!ictx)
                return;

        /*
         * if we get a callback before we're done configuring the hardware, we
         * can't yet process the data, as there's nowhere to send it, but we
         * still need to submit a new rx URB to avoid wedging the hardware
         */
        if (!ictx->dev_present_intf1)
                goto out;

        switch (urb->status) {
        case -ENOENT:           /* usbcore unlink successful! */
                return;

        case -ESHUTDOWN:        /* transport endpoint was shut down */
                break;

        case 0:
                imon_incoming_packet(ictx, urb, intfnum);
                break;

        default:
                dev_warn(ictx->dev, "imon %s: status(%d): ignored\n",
                         __func__, urb->status);
                break;
        }

out:
        usb_submit_urb(ictx->rx_urb_intf1, GFP_ATOMIC);
}

/*
 * The 0x15c2:0xffdc device ID was used for umpteen different imon
 * devices, and all of them constantly spew interrupts, even when there
 * is no actual data to report. However, byte 6 of this buffer looks like
 * its unique across device variants, so we're trying to key off that to
 * figure out which display type (if any) and what IR protocol the device
 * actually supports. These devices have their IR protocol hard-coded into
 * their firmware, they can't be changed on the fly like the newer hardware.
 */
static void imon_get_ffdc_type(struct imon_context *ictx)
{
        u8 ffdc_cfg_byte = ictx->usb_rx_buf[6];
        u8 detected_display_type = IMON_DISPLAY_TYPE_NONE;
        u64 allowed_protos = RC_PROTO_BIT_IMON;

        switch (ffdc_cfg_byte) {
        /* iMON Knob, no display, iMON IR + vol knob */
        case 0x21:
                dev_info(ictx->dev, "0xffdc iMON Knob, iMON IR");
                ictx->display_supported = false;
                break;
        /* iMON 2.4G LT (usb stick), no display, iMON RF */
        case 0x4e:
                dev_info(ictx->dev, "0xffdc iMON 2.4G LT, iMON RF");
                ictx->display_supported = false;
                ictx->rf_device = true;
                break;
        /* iMON VFD, no IR (does have vol knob tho) */
        case 0x35:
                dev_info(ictx->dev, "0xffdc iMON VFD + knob, no IR");
                detected_display_type = IMON_DISPLAY_TYPE_VFD;
                break;
        /* iMON VFD, iMON IR */
        case 0x24:
        case 0x30:
        case 0x85:
                dev_info(ictx->dev, "0xffdc iMON VFD, iMON IR");
                detected_display_type = IMON_DISPLAY_TYPE_VFD;
                break;
        /* iMON VFD, MCE IR */
        case 0x46:
        case 0x7e:
        case 0x9e:
                dev_info(ictx->dev, "0xffdc iMON VFD, MCE IR");
                detected_display_type = IMON_DISPLAY_TYPE_VFD;
                allowed_protos = RC_PROTO_BIT_RC6_MCE;
                break;
        /* iMON LCD, MCE IR */
        case 0x9f:
                dev_info(ictx->dev, "0xffdc iMON LCD, MCE IR");
                detected_display_type = IMON_DISPLAY_TYPE_LCD;
                allowed_protos = RC_PROTO_BIT_RC6_MCE;
                break;
        /* no display, iMON IR */
        case 0x26:
                dev_info(ictx->dev, "0xffdc iMON Inside, iMON IR");
                ictx->display_supported = false;
                break;
        default:
                dev_info(ictx->dev, "Unknown 0xffdc device, defaulting to VFD and iMON IR");
                detected_display_type = IMON_DISPLAY_TYPE_VFD;
                /*
                 * We don't know which one it is, allow user to set the
                 * RC6 one from userspace if IMON wasn't correct.
                 */
                allowed_protos |= RC_PROTO_BIT_RC6_MCE;
                break;
        }

        printk(KERN_CONT " (id 0x%02x)\n", ffdc_cfg_byte);

        ictx->display_type = detected_display_type;
        ictx->rc_proto = allowed_protos;
}

static void imon_set_display_type(struct imon_context *ictx)
{
        u8 configured_display_type = IMON_DISPLAY_TYPE_VFD;

        /*
         * Try to auto-detect the type of display if the user hasn't set
         * it by hand via the display_type modparam. Default is VFD.
         */

        if (display_type == IMON_DISPLAY_TYPE_AUTO) {
                switch (ictx->product) {
                case 0xffdc:
                        /* set in imon_get_ffdc_type() */
                        configured_display_type = ictx->display_type;
                        break;
                case 0x0034:
                case 0x0035:
                        configured_display_type = IMON_DISPLAY_TYPE_VGA;
                        break;
                case 0x0038:
                case 0x0039:
                case 0x0045:
                        configured_display_type = IMON_DISPLAY_TYPE_LCD;
                        break;
                case 0x003c:
                case 0x0041:
                case 0x0042:
                case 0x0043:
                        configured_display_type = IMON_DISPLAY_TYPE_NONE;
                        ictx->display_supported = false;
                        break;
                case 0x0036:
                case 0x0044:
                default:
                        configured_display_type = IMON_DISPLAY_TYPE_VFD;
                        break;
                }
        } else {
                configured_display_type = display_type;
                if (display_type == IMON_DISPLAY_TYPE_NONE)
                        ictx->display_supported = false;
                else
                        ictx->display_supported = true;
                dev_info(ictx->dev, "%s: overriding display type to %d via modparam\n",
                         __func__, display_type);
        }

        ictx->display_type = configured_display_type;
}

static struct rc_dev *imon_init_rdev(struct imon_context *ictx)
{
        struct rc_dev *rdev;
        int ret;
        static const unsigned char fp_packet[] = {
                0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88 };

        rdev = rc_allocate_device(RC_DRIVER_SCANCODE);
        if (!rdev) {
                dev_err(ictx->dev, "remote control dev allocation failed\n");
                goto out;
        }

        snprintf(ictx->name_rdev, sizeof(ictx->name_rdev),
                 "iMON Remote (%04x:%04x)", ictx->vendor, ictx->product);
        usb_make_path(ictx->usbdev_intf0, ictx->phys_rdev,
                      sizeof(ictx->phys_rdev));
        strlcat(ictx->phys_rdev, "/input0", sizeof(ictx->phys_rdev));

        rdev->device_name = ictx->name_rdev;
        rdev->input_phys = ictx->phys_rdev;
        usb_to_input_id(ictx->usbdev_intf0, &rdev->input_id);
        rdev->dev.parent = ictx->dev;

        rdev->priv = ictx;
        /* iMON PAD or MCE */
        rdev->allowed_protocols = RC_PROTO_BIT_IMON | RC_PROTO_BIT_RC6_MCE;
        rdev->change_protocol = imon_ir_change_protocol;
        rdev->driver_name = MOD_NAME;

        /* Enable front-panel buttons and/or knobs */
        memcpy(ictx->usb_tx_buf, &fp_packet, sizeof(fp_packet));
        ret = send_packet(ictx);
        /* Not fatal, but warn about it */
        if (ret)
                dev_info(ictx->dev, "panel buttons/knobs setup failed\n");

        if (ictx->product == 0xffdc) {
                imon_get_ffdc_type(ictx);
                rdev->allowed_protocols = ictx->rc_proto;
        }

        imon_set_display_type(ictx);

        if (ictx->rc_proto == RC_PROTO_BIT_RC6_MCE)
                rdev->map_name = RC_MAP_IMON_MCE;
        else
                rdev->map_name = RC_MAP_IMON_PAD;

        ret = rc_register_device(rdev);
        if (ret < 0) {
                dev_err(ictx->dev, "remote input dev register failed\n");
                goto out;
        }

        return rdev;

out:
        rc_free_device(rdev);
        return NULL;
}

static struct input_dev *imon_init_idev(struct imon_context *ictx)
{
        struct imon_panel_key_table *key_table = ictx->dev_descr->key_table;
        struct input_dev *idev;
        int ret, i;

        idev = input_allocate_device();
        if (!idev)
                goto out;

        snprintf(ictx->name_idev, sizeof(ictx->name_idev),
                 "iMON Panel, Knob and Mouse(%04x:%04x)",
                 ictx->vendor, ictx->product);
        idev->name = ictx->name_idev;

        usb_make_path(ictx->usbdev_intf0, ictx->phys_idev,
                      sizeof(ictx->phys_idev));

        strlcat(ictx->phys_idev, "/input1", sizeof(ictx->phys_idev));
        idev->phys = ictx->phys_idev;

        idev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP) | BIT_MASK(EV_REL);

        idev->keybit[BIT_WORD(BTN_MOUSE)] =
                BIT_MASK(BTN_LEFT) | BIT_MASK(BTN_RIGHT);
        idev->relbit[0] = BIT_MASK(REL_X) | BIT_MASK(REL_Y) |
                BIT_MASK(REL_WHEEL);

        /* panel and/or knob code support */
        for (i = 0; key_table[i].hw_code != 0; i++) {
                u32 kc = key_table[i].keycode;
                __set_bit(kc, idev->keybit);
        }

        usb_to_input_id(ictx->usbdev_intf0, &idev->id);
        idev->dev.parent = ictx->dev;
        input_set_drvdata(idev, ictx);

        ret = input_register_device(idev);
        if (ret < 0) {
                dev_err(ictx->dev, "input dev register failed\n");
                goto out;
        }

        return idev;

out:
        input_free_device(idev);
        return NULL;
}

static struct input_dev *imon_init_touch(struct imon_context *ictx)
{
        struct input_dev *touch;
        int ret;

        touch = input_allocate_device();
        if (!touch)
                goto touch_alloc_failed;

        snprintf(ictx->name_touch, sizeof(ictx->name_touch),
                 "iMON USB Touchscreen (%04x:%04x)",
                 ictx->vendor, ictx->product);
        touch->name = ictx->name_touch;

        usb_make_path(ictx->usbdev_intf1, ictx->phys_touch,
                      sizeof(ictx->phys_touch));
        strlcat(ictx->phys_touch, "/input2", sizeof(ictx->phys_touch));
        touch->phys = ictx->phys_touch;

        touch->evbit[0] =
                BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
        touch->keybit[BIT_WORD(BTN_TOUCH)] =
                BIT_MASK(BTN_TOUCH);
        input_set_abs_params(touch, ABS_X,
                             0x00, 0xfff, 0, 0);
        input_set_abs_params(touch, ABS_Y,
                             0x00, 0xfff, 0, 0);

        input_set_drvdata(touch, ictx);

        usb_to_input_id(ictx->usbdev_intf1, &touch->id);
        touch->dev.parent = ictx->dev;
        ret = input_register_device(touch);
        if (ret <  0) {
                dev_info(ictx->dev, "touchscreen input dev register failed\n");
                goto touch_register_failed;
        }

        return touch;

touch_register_failed:
        input_free_device(touch);

touch_alloc_failed:
        return NULL;
}

static bool imon_find_endpoints(struct imon_context *ictx,
                                struct usb_host_interface *iface_desc)
{
        struct usb_endpoint_descriptor *ep;
        struct usb_endpoint_descriptor *rx_endpoint = NULL;
        struct usb_endpoint_descriptor *tx_endpoint = NULL;
        int ifnum = iface_desc->desc.bInterfaceNumber;
        int num_endpts = iface_desc->desc.bNumEndpoints;
        int i, ep_dir, ep_type;
        bool ir_ep_found = false;
        bool display_ep_found = false;
        bool tx_control = false;

        /*
         * Scan the endpoint list and set:
         *      first input endpoint = IR endpoint
         *      first output endpoint = display endpoint
         */
        for (i = 0; i < num_endpts && !(ir_ep_found && display_ep_found); ++i) {
                ep = &iface_desc->endpoint[i].desc;
                ep_dir = ep->bEndpointAddress & USB_ENDPOINT_DIR_MASK;
                ep_type = usb_endpoint_type(ep);

                if (!ir_ep_found && ep_dir == USB_DIR_IN &&
                    ep_type == USB_ENDPOINT_XFER_INT) {

                        rx_endpoint = ep;
                        ir_ep_found = true;
                        dev_dbg(ictx->dev, "%s: found IR endpoint\n", __func__);

                } else if (!display_ep_found && ep_dir == USB_DIR_OUT &&
                           ep_type == USB_ENDPOINT_XFER_INT) {
                        tx_endpoint = ep;
                        display_ep_found = true;
                        dev_dbg(ictx->dev, "%s: found display endpoint\n", __func__);
                }
        }

        if (ifnum == 0) {
                ictx->rx_endpoint_intf0 = rx_endpoint;
                /*
                 * tx is used to send characters to lcd/vfd, associate RF
                 * remotes, set IR protocol, and maybe more...
                 */
                ictx->tx_endpoint = tx_endpoint;
        } else {
                ictx->rx_endpoint_intf1 = rx_endpoint;
        }

        /*
         * If we didn't find a display endpoint, this is probably one of the
         * newer iMON devices that use control urb instead of interrupt
         */
        if (!display_ep_found) {
                tx_control = true;
                display_ep_found = true;
                dev_dbg(ictx->dev, "%s: device uses control endpoint, not interface OUT endpoint\n",
                        __func__);
        }

        /*
         * Some iMON receivers have no display. Unfortunately, it seems
         * that SoundGraph recycles device IDs between devices both with
         * and without... :\
         */
        if (ictx->display_type == IMON_DISPLAY_TYPE_NONE) {
                display_ep_found = false;
                dev_dbg(ictx->dev, "%s: device has no display\n", __func__);
        }

        /*
         * iMON Touch devices have a VGA touchscreen, but no "display", as
         * that refers to e.g. /dev/lcd0 (a character device LCD or VFD).
         */
        if (ictx->display_type == IMON_DISPLAY_TYPE_VGA) {
                display_ep_found = false;
                dev_dbg(ictx->dev, "%s: iMON Touch device found\n", __func__);
        }

        /* Input endpoint is mandatory */
        if (!ir_ep_found)
                pr_err("no valid input (IR) endpoint found\n");

        ictx->tx_control = tx_control;

        if (display_ep_found)
                ictx->display_supported = true;

        return ir_ep_found;

}

static struct imon_context *imon_init_intf0(struct usb_interface *intf,
                                            const struct usb_device_id *id)
{
        struct imon_context *ictx;
        struct urb *rx_urb;
        struct urb *tx_urb;
        struct device *dev = &intf->dev;
        struct usb_host_interface *iface_desc;
        int ret = -ENOMEM;

        ictx = kzalloc(sizeof(*ictx), GFP_KERNEL);
        if (!ictx)
                goto exit;

        rx_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!rx_urb)
                goto rx_urb_alloc_failed;
        tx_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!tx_urb)
                goto tx_urb_alloc_failed;

        mutex_init(&ictx->lock);
        spin_lock_init(&ictx->kc_lock);

        mutex_lock(&ictx->lock);

        ictx->dev = dev;
        ictx->usbdev_intf0 = usb_get_dev(interface_to_usbdev(intf));
        ictx->rx_urb_intf0 = rx_urb;
        ictx->tx_urb = tx_urb;
        ictx->rf_device = false;

        init_completion(&ictx->tx.finished);

        ictx->vendor  = le16_to_cpu(ictx->usbdev_intf0->descriptor.idVendor);
        ictx->product = le16_to_cpu(ictx->usbdev_intf0->descriptor.idProduct);

        /* save drive info for later accessing the panel/knob key table */
        ictx->dev_descr = (struct imon_usb_dev_descr *)id->driver_info;
        /* default send_packet delay is 5ms but some devices need more */
        ictx->send_packet_delay = ictx->dev_descr->flags &
                                  IMON_NEED_20MS_PKT_DELAY ? 20 : 5;

        ret = -ENODEV;
        iface_desc = intf->cur_altsetting;
        if (!imon_find_endpoints(ictx, iface_desc)) {
                goto find_endpoint_failed;
        }

        usb_fill_int_urb(ictx->rx_urb_intf0, ictx->usbdev_intf0,
                usb_rcvintpipe(ictx->usbdev_intf0,
                        ictx->rx_endpoint_intf0->bEndpointAddress),
                ictx->usb_rx_buf, sizeof(ictx->usb_rx_buf),
                usb_rx_callback_intf0, ictx,
                ictx->rx_endpoint_intf0->bInterval);

        ret = usb_submit_urb(ictx->rx_urb_intf0, GFP_KERNEL);
        if (ret) {
                pr_err("usb_submit_urb failed for intf0 (%d)\n", ret);
                goto urb_submit_failed;
        }

        ictx->idev = imon_init_idev(ictx);
        if (!ictx->idev) {
                dev_err(dev, "%s: input device setup failed\n", __func__);
                goto idev_setup_failed;
        }

        ictx->rdev = imon_init_rdev(ictx);
        if (!ictx->rdev) {
                dev_err(dev, "%s: rc device setup failed\n", __func__);
                goto rdev_setup_failed;
        }

        ictx->dev_present_intf0 = true;

        mutex_unlock(&ictx->lock);
        return ictx;

rdev_setup_failed:
        input_unregister_device(ictx->idev);
idev_setup_failed:
        usb_kill_urb(ictx->rx_urb_intf0);
urb_submit_failed:
find_endpoint_failed:
        usb_put_dev(ictx->usbdev_intf0);
        mutex_unlock(&ictx->lock);
        usb_free_urb(tx_urb);
tx_urb_alloc_failed:
        usb_free_urb(rx_urb);
rx_urb_alloc_failed:
        kfree(ictx);
exit:
        dev_err(dev, "unable to initialize intf0, err %d\n", ret);

        return NULL;
}

static struct imon_context *imon_init_intf1(struct usb_interface *intf,
                                            struct imon_context *ictx)
{
        struct urb *rx_urb;
        struct usb_host_interface *iface_desc;
        int ret = -ENOMEM;

        rx_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!rx_urb)
                goto rx_urb_alloc_failed;

        mutex_lock(&ictx->lock);

        if (ictx->display_type == IMON_DISPLAY_TYPE_VGA) {
                timer_setup(&ictx->ttimer, imon_touch_display_timeout, 0);
        }

        ictx->usbdev_intf1 = usb_get_dev(interface_to_usbdev(intf));
        ictx->rx_urb_intf1 = rx_urb;

        ret = -ENODEV;
        iface_desc = intf->cur_altsetting;
        if (!imon_find_endpoints(ictx, iface_desc))
                goto find_endpoint_failed;

        if (ictx->display_type == IMON_DISPLAY_TYPE_VGA) {
                ictx->touch = imon_init_touch(ictx);
                if (!ictx->touch)
                        goto touch_setup_failed;
        } else
                ictx->touch = NULL;

        usb_fill_int_urb(ictx->rx_urb_intf1, ictx->usbdev_intf1,
                usb_rcvintpipe(ictx->usbdev_intf1,
                        ictx->rx_endpoint_intf1->bEndpointAddress),
                ictx->usb_rx_buf, sizeof(ictx->usb_rx_buf),
                usb_rx_callback_intf1, ictx,
                ictx->rx_endpoint_intf1->bInterval);

        ret = usb_submit_urb(ictx->rx_urb_intf1, GFP_KERNEL);

        if (ret) {
                pr_err("usb_submit_urb failed for intf1 (%d)\n", ret);
                goto urb_submit_failed;
        }

        ictx->dev_present_intf1 = true;

        mutex_unlock(&ictx->lock);
        return ictx;

urb_submit_failed:
        if (ictx->touch)
                input_unregister_device(ictx->touch);
touch_setup_failed:
find_endpoint_failed:
        usb_put_dev(ictx->usbdev_intf1);
        mutex_unlock(&ictx->lock);
        usb_free_urb(rx_urb);
rx_urb_alloc_failed:
        dev_err(ictx->dev, "unable to initialize intf1, err %d\n", ret);

        return NULL;
}

static void imon_init_display(struct imon_context *ictx,
                              struct usb_interface *intf)
{
        int ret;

        dev_dbg(ictx->dev, "Registering iMON display with sysfs\n");

        /* set up sysfs entry for built-in clock */
        ret = sysfs_create_group(&intf->dev.kobj, &imon_display_attr_group);
        if (ret)
                dev_err(ictx->dev, "Could not create display sysfs entries(%d)",
                        ret);

        if (ictx->display_type == IMON_DISPLAY_TYPE_LCD)
                ret = usb_register_dev(intf, &imon_lcd_class);
        else
                ret = usb_register_dev(intf, &imon_vfd_class);
        if (ret)
                /* Not a fatal error, so ignore */
                dev_info(ictx->dev, "could not get a minor number for display\n");

}

/*
 * Callback function for USB core API: Probe
 */
static int imon_probe(struct usb_interface *interface,
                      const struct usb_device_id *id)
{
        struct usb_device *usbdev = NULL;
        struct usb_host_interface *iface_desc = NULL;
        struct usb_interface *first_if;
        struct device *dev = &interface->dev;
        int ifnum, sysfs_err;
        int ret = 0;
        struct imon_context *ictx = NULL;
        struct imon_context *first_if_ctx = NULL;
        u16 vendor, product;

        usbdev     = usb_get_dev(interface_to_usbdev(interface));
        iface_desc = interface->cur_altsetting;
        ifnum      = iface_desc->desc.bInterfaceNumber;
        vendor     = le16_to_cpu(usbdev->descriptor.idVendor);
        product    = le16_to_cpu(usbdev->descriptor.idProduct);

        dev_dbg(dev, "%s: found iMON device (%04x:%04x, intf%d)\n",
                __func__, vendor, product, ifnum);

        /* prevent races probing devices w/multiple interfaces */
        mutex_lock(&driver_lock);

        first_if = usb_ifnum_to_if(usbdev, 0);
        if (!first_if) {
                ret = -ENODEV;
                goto fail;
        }

        first_if_ctx = usb_get_intfdata(first_if);

        if (ifnum == 0) {
                ictx = imon_init_intf0(interface, id);
                if (!ictx) {
                        pr_err("failed to initialize context!\n");
                        ret = -ENODEV;
                        goto fail;
                }

        } else {
                /* this is the secondary interface on the device */

                /* fail early if first intf failed to register */
                if (!first_if_ctx) {
                        ret = -ENODEV;
                        goto fail;
                }

                ictx = imon_init_intf1(interface, first_if_ctx);
                if (!ictx) {
                        pr_err("failed to attach to context!\n");
                        ret = -ENODEV;
                        goto fail;
                }

        }

        usb_set_intfdata(interface, ictx);

        if (ifnum == 0) {
                mutex_lock(&ictx->lock);

                if (product == 0xffdc && ictx->rf_device) {
                        sysfs_err = sysfs_create_group(&interface->dev.kobj,
                                                       &imon_rf_attr_group);
                        if (sysfs_err)
                                pr_err("Could not create RF sysfs entries(%d)\n",
                                       sysfs_err);
                }

                if (ictx->display_supported)
                        imon_init_display(ictx, interface);

                mutex_unlock(&ictx->lock);
        }

        dev_info(dev, "iMON device (%04x:%04x, intf%d) on usb<%d:%d> initialized\n",
                 vendor, product, ifnum,
                 usbdev->bus->busnum, usbdev->devnum);

        mutex_unlock(&driver_lock);
        usb_put_dev(usbdev);

        return 0;

fail:
        mutex_unlock(&driver_lock);
        usb_put_dev(usbdev);
        dev_err(dev, "unable to register, err %d\n", ret);

        return ret;
}

/*
 * Callback function for USB core API: disconnect
 */
static void imon_disconnect(struct usb_interface *interface)
{
        struct imon_context *ictx;
        struct device *dev;
        int ifnum;

        /* prevent races with multi-interface device probing and display_open */
        mutex_lock(&driver_lock);

        ictx = usb_get_intfdata(interface);
        dev = ictx->dev;
        ifnum = interface->cur_altsetting->desc.bInterfaceNumber;

        /*
         * sysfs_remove_group is safe to call even if sysfs_create_group
         * hasn't been called
         */
        sysfs_remove_group(&interface->dev.kobj, &imon_display_attr_group);
        sysfs_remove_group(&interface->dev.kobj, &imon_rf_attr_group);

        usb_set_intfdata(interface, NULL);

        /* Abort ongoing write */
        if (ictx->tx.busy) {
                usb_kill_urb(ictx->tx_urb);
                complete(&ictx->tx.finished);
        }

        if (ifnum == 0) {
                ictx->dev_present_intf0 = false;
                usb_kill_urb(ictx->rx_urb_intf0);
                usb_put_dev(ictx->usbdev_intf0);
                input_unregister_device(ictx->idev);
                rc_unregister_device(ictx->rdev);
                if (ictx->display_supported) {
                        if (ictx->display_type == IMON_DISPLAY_TYPE_LCD)
                                usb_deregister_dev(interface, &imon_lcd_class);
                        else if (ictx->display_type == IMON_DISPLAY_TYPE_VFD)
                                usb_deregister_dev(interface, &imon_vfd_class);
                }
        } else {
                ictx->dev_present_intf1 = false;
                usb_kill_urb(ictx->rx_urb_intf1);
                usb_put_dev(ictx->usbdev_intf1);
                if (ictx->display_type == IMON_DISPLAY_TYPE_VGA) {
                        input_unregister_device(ictx->touch);
                        del_timer_sync(&ictx->ttimer);
                }
        }

        if (!ictx->dev_present_intf0 && !ictx->dev_present_intf1)
                free_imon_context(ictx);

        mutex_unlock(&driver_lock);

        dev_dbg(dev, "%s: iMON device (intf%d) disconnected\n",
                __func__, ifnum);
}

static int imon_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct imon_context *ictx = usb_get_intfdata(intf);
        int ifnum = intf->cur_altsetting->desc.bInterfaceNumber;

        if (ifnum == 0)
                usb_kill_urb(ictx->rx_urb_intf0);
        else
                usb_kill_urb(ictx->rx_urb_intf1);

        return 0;
}

static int imon_resume(struct usb_interface *intf)
{
        int rc = 0;
        struct imon_context *ictx = usb_get_intfdata(intf);
        int ifnum = intf->cur_altsetting->desc.bInterfaceNumber;

        if (ifnum == 0) {
                usb_fill_int_urb(ictx->rx_urb_intf0, ictx->usbdev_intf0,
                        usb_rcvintpipe(ictx->usbdev_intf0,
                                ictx->rx_endpoint_intf0->bEndpointAddress),
                        ictx->usb_rx_buf, sizeof(ictx->usb_rx_buf),
                        usb_rx_callback_intf0, ictx,
                        ictx->rx_endpoint_intf0->bInterval);

                rc = usb_submit_urb(ictx->rx_urb_intf0, GFP_ATOMIC);

        } else {
                usb_fill_int_urb(ictx->rx_urb_intf1, ictx->usbdev_intf1,
                        usb_rcvintpipe(ictx->usbdev_intf1,
                                ictx->rx_endpoint_intf1->bEndpointAddress),
                        ictx->usb_rx_buf, sizeof(ictx->usb_rx_buf),
                        usb_rx_callback_intf1, ictx,
                        ictx->rx_endpoint_intf1->bInterval);

                rc = usb_submit_urb(ictx->rx_urb_intf1, GFP_ATOMIC);
        }

        return rc;
}

module_usb_driver(imon_driver);