/*
 * lirc_sasem.c - USB remote support for LIRC
 * Version 0.5
 *
 * Copyright (C) 2004-2005 Oliver Stabel <oliver.stabel@gmx.de>
 *			 Tim Davies <tim@opensystems.net.au>
 *
 * This driver was derived from:
 *   Venky Raju <dev@venky.ws>
 *      "lirc_imon - "LIRC/VFD driver for Ahanix/Soundgraph IMON IR/VFD"
 *   Paul Miller <pmiller9@users.sourceforge.net>'s 2003-2004
 *      "lirc_atiusb - USB remote support for LIRC"
 *   Culver Consulting Services <henry@culcon.com>'s 2003
 *      "Sasem OnAir VFD/IR USB driver"
 *
 *
 * NOTE - The LCDproc iMon driver should work with this module.  More info at
 *	http://www.frogstorm.info/sasem
 */

/*
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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

#include <media/lirc.h>
#include <media/lirc_dev.h>


#define MOD_AUTHOR	"Oliver Stabel <oliver.stabel@gmx.de>, " \
			"Tim Davies <tim@opensystems.net.au>"
#define MOD_DESC	"USB Driver for Sasem Remote Controller V1.1"
#define MOD_NAME	"lirc_sasem"
#define MOD_VERSION	"0.5"

#define VFD_MINOR_BASE	144	/* Same as LCD */
#define DEVICE_NAME	"lcd%d"

#define BUF_CHUNK_SIZE	8
#define BUF_SIZE	128

#define IOCTL_LCD_CONTRAST 1

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

/* USB Callback prototypes */
static int sasem_probe(struct usb_interface *interface,
			const struct usb_device_id *id);
static void sasem_disconnect(struct usb_interface *interface);
static void usb_rx_callback(struct urb *urb);
static void usb_tx_callback(struct urb *urb);

/* VFD file_operations function prototypes */
static int vfd_open(struct inode *inode, struct file *file);
static long vfd_ioctl(struct file *file, unsigned cmd, unsigned long arg);
static int vfd_close(struct inode *inode, struct file *file);
static ssize_t vfd_write(struct file *file, const char __user *buf,
				size_t n_bytes, loff_t *pos);

/* LIRC driver function prototypes */
static int ir_open(void *data);
static void ir_close(void *data);

/*** G L O B A L S ***/
#define SASEM_DATA_BUF_SZ	32

struct sasem_context {

	struct usb_device *dev;
	int vfd_isopen;			/* VFD port has been opened */
	unsigned int vfd_contrast;	/* VFD contrast */
	int ir_isopen;			/* IR port has been opened */
	int dev_present;		/* USB device presence */
	struct mutex ctx_lock;		/* to lock this object */
	wait_queue_head_t remove_ok;	/* For unexpected USB disconnects */

	struct lirc_driver *driver;
	struct usb_endpoint_descriptor *rx_endpoint;
	struct usb_endpoint_descriptor *tx_endpoint;
	struct urb *rx_urb;
	struct urb *tx_urb;
	unsigned char usb_rx_buf[8];
	unsigned char usb_tx_buf[8];

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

	/* for dealing with repeat codes (wish there was a toggle bit!) */
	ktime_t presstime;
	char lastcode[8];
	int codesaved;
};

/* VFD file operations */
static const struct file_operations vfd_fops = {
	.owner		= THIS_MODULE,
	.open		= &vfd_open,
	.write		= vfd_write,
	.unlocked_ioctl	= &vfd_ioctl,
	.release	= &vfd_close,
	.llseek		= noop_llseek,
};

/* USB Device ID for Sasem USB Control Board */
static struct usb_device_id sasem_usb_id_table[] = {
	/* Sasem USB Control Board */
	{ USB_DEVICE(0x11ba, 0x0101) },
	/* Terminating entry */
	{}
};

/* USB Device data */
static struct usb_driver sasem_driver = {
	.name		= MOD_NAME,
	.probe		= sasem_probe,
	.disconnect	= sasem_disconnect,
	.id_table	= sasem_usb_id_table,
};

static struct usb_class_driver sasem_class = {
	.name		= DEVICE_NAME,
	.fops		= &vfd_fops,
	.minor_base	= VFD_MINOR_BASE,
};

/* to prevent races between open() and disconnect() */
static DEFINE_MUTEX(disconnect_lock);

static int debug;


/*** M O D U L E   C O D E ***/

MODULE_AUTHOR(MOD_AUTHOR);
MODULE_DESCRIPTION(MOD_DESC);
MODULE_LICENSE("GPL");
module_param(debug, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug messages: 0=no, 1=yes (default: no)");

static void delete_context(struct sasem_context *context)
{
	usb_free_urb(context->tx_urb);  /* VFD */
	usb_free_urb(context->rx_urb);  /* IR */
	lirc_buffer_free(context->driver->rbuf);
	kfree(context->driver->rbuf);
	kfree(context->driver);
	kfree(context);
}

static void deregister_from_lirc(struct sasem_context *context)
{
	int retval;
	int minor = context->driver->minor;

	retval = lirc_unregister_driver(minor);
	if (retval)
		dev_err(&context->dev->dev,
			"%s: unable to deregister from lirc (%d)\n",
			__func__, retval);
	else
		dev_info(&context->dev->dev,
			 "Deregistered Sasem driver (minor:%d)\n", minor);

}

/**
 * Called when the VFD device (e.g. /dev/usb/lcd)
 * is opened by the application.
 */
static int vfd_open(struct inode *inode, struct file *file)
{
	struct usb_interface *interface;
	struct sasem_context *context = NULL;
	int subminor;
	int retval = 0;

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

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

	if (!context) {
		dev_err(&interface->dev, "no context found for minor %d\n",
			subminor);
		retval = -ENODEV;
		goto exit;
	}

	mutex_lock(&context->ctx_lock);

	if (context->vfd_isopen) {
		dev_err(&interface->dev,
			"%s: VFD port is already open", __func__);
		retval = -EBUSY;
	} else {
		context->vfd_isopen = 1;
		file->private_data = context;
		dev_info(&interface->dev, "VFD port opened\n");
	}

	mutex_unlock(&context->ctx_lock);

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

/**
 * Called when the VFD device (e.g. /dev/usb/lcd)
 * is closed by the application.
 */
static long vfd_ioctl(struct file *file, unsigned cmd, unsigned long arg)
{
	struct sasem_context *context;

	context = (struct sasem_context *) file->private_data;

	if (!context) {
		pr_err("%s: no context for device\n", __func__);
		return -ENODEV;
	}

	mutex_lock(&context->ctx_lock);

	switch (cmd) {
	case IOCTL_LCD_CONTRAST:
		if (arg > 1000)
			arg = 1000;
		context->vfd_contrast = (unsigned int)arg;
		break;
	default:
		pr_info("Unknown IOCTL command\n");
		mutex_unlock(&context->ctx_lock);
		return -ENOIOCTLCMD;  /* not supported */
	}

	mutex_unlock(&context->ctx_lock);
	return 0;
}

/**
 * Called when the VFD device (e.g. /dev/usb/lcd)
 * is closed by the application.
 */
static int vfd_close(struct inode *inode, struct file *file)
{
	struct sasem_context *context = NULL;
	int retval = 0;

	context = (struct sasem_context *) file->private_data;

	if (!context) {
		pr_err("%s: no context for device\n", __func__);
		return -ENODEV;
	}

	mutex_lock(&context->ctx_lock);

	if (!context->vfd_isopen) {
		dev_err(&context->dev->dev, "%s: VFD is not open\n", __func__);
		retval = -EIO;
	} else {
		context->vfd_isopen = 0;
		dev_info(&context->dev->dev, "VFD port closed\n");
		if (!context->dev_present && !context->ir_isopen) {

			/* Device disconnected before close and IR port is
			 * not open. If IR port is open, context will be
			 * deleted by ir_close. */
			mutex_unlock(&context->ctx_lock);
			delete_context(context);
			return retval;
		}
	}

	mutex_unlock(&context->ctx_lock);
	return retval;
}

/**
 * Sends a packet to the VFD.
 */
static int send_packet(struct sasem_context *context)
{
	unsigned int pipe;
	int interval = 0;
	int retval = 0;

	pipe = usb_sndintpipe(context->dev,
			context->tx_endpoint->bEndpointAddress);
	interval = context->tx_endpoint->bInterval;

	usb_fill_int_urb(context->tx_urb, context->dev, pipe,
		context->usb_tx_buf, sizeof(context->usb_tx_buf),
		usb_tx_callback, context, interval);

	context->tx_urb->actual_length = 0;

	init_completion(&context->tx.finished);
	atomic_set(&context->tx.busy, 1);

	retval =  usb_submit_urb(context->tx_urb, GFP_KERNEL);
	if (retval) {
		atomic_set(&context->tx.busy, 0);
		dev_err(&context->dev->dev, "error submitting urb (%d)\n",
			retval);
	} else {
		/* Wait for transmission to complete (or abort) */
		mutex_unlock(&context->ctx_lock);
		wait_for_completion(&context->tx.finished);
		mutex_lock(&context->ctx_lock);

		retval = context->tx.status;
		if (retval)
			dev_err(&context->dev->dev,
				"packet tx failed (%d)\n", retval);
	}

	return retval;
}

/**
 * Writes data to the VFD.  The Sasem VFD is 2x16 characters
 * and requires data in 9 consecutive USB interrupt packets,
 * each packet carrying 8 bytes.
 */
static ssize_t vfd_write(struct file *file, const char __user *buf,
				size_t n_bytes, loff_t *pos)
{
	int i;
	int retval = 0;
	struct sasem_context *context;
	int *data_buf = NULL;

	context = (struct sasem_context *) file->private_data;
	if (!context) {
		pr_err("%s: no context for device\n", __func__);
		return -ENODEV;
	}

	mutex_lock(&context->ctx_lock);

	if (!context->dev_present) {
		pr_err("%s: no Sasem device present\n", __func__);
		retval = -ENODEV;
		goto exit;
	}

	if (n_bytes <= 0 || n_bytes > SASEM_DATA_BUF_SZ) {
		dev_err(&context->dev->dev, "%s: invalid payload size\n",
			__func__);
		retval = -EINVAL;
		goto exit;
	}

	data_buf = memdup_user(buf, n_bytes);
	if (IS_ERR(data_buf)) {
		retval = PTR_ERR(data_buf);
		data_buf = NULL;
		goto exit;
	}

	memcpy(context->tx.data_buf, data_buf, n_bytes);

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

	/* Nine 8 byte packets to be sent */
	/* NOTE: "\x07\x01\0\0\0\0\0\0" or "\x0c\0\0\0\0\0\0\0"
	 *       will clear the VFD */
	for (i = 0; i < 9; i++) {
		switch (i) {
		case 0:
			memcpy(context->usb_tx_buf, "\x07\0\0\0\0\0\0\0", 8);
			context->usb_tx_buf[1] = (context->vfd_contrast) ?
				(0x2B - (context->vfd_contrast - 1) / 250)
				: 0x2B;
			break;
		case 1:
			memcpy(context->usb_tx_buf, "\x09\x01\0\0\0\0\0\0", 8);
			break;
		case 2:
			memcpy(context->usb_tx_buf, "\x0b\x01\0\0\0\0\0\0", 8);
			break;
		case 3:
			memcpy(context->usb_tx_buf, context->tx.data_buf, 8);
			break;
		case 4:
			memcpy(context->usb_tx_buf,
			       context->tx.data_buf + 8, 8);
			break;
		case 5:
			memcpy(context->usb_tx_buf, "\x09\x01\0\0\0\0\0\0", 8);
			break;
		case 6:
			memcpy(context->usb_tx_buf, "\x0b\x02\0\0\0\0\0\0", 8);
			break;
		case 7:
			memcpy(context->usb_tx_buf,
			       context->tx.data_buf + 16, 8);
			break;
		case 8:
			memcpy(context->usb_tx_buf,
			       context->tx.data_buf + 24, 8);
			break;
		}
		retval = send_packet(context);
		if (retval) {
			dev_err(&context->dev->dev,
				"send packet failed for packet #%d\n", i);
			goto exit;
		}
	}
exit:

	mutex_unlock(&context->ctx_lock);
	kfree(data_buf);

	return (!retval) ? n_bytes : retval;
}

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

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

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

	/* notify waiters that write has finished */
	atomic_set(&context->tx.busy, 0);
	complete(&context->tx.finished);
}

/**
 * Called by lirc_dev when the application opens /dev/lirc
 */
static int ir_open(void *data)
{
	int retval = 0;
	struct sasem_context *context;

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

	context = data;

	mutex_lock(&context->ctx_lock);

	if (context->ir_isopen) {
		dev_err(&context->dev->dev, "%s: IR port is already open\n",
			__func__);
		retval = -EBUSY;
		goto exit;
	}

	usb_fill_int_urb(context->rx_urb, context->dev,
		usb_rcvintpipe(context->dev,
				context->rx_endpoint->bEndpointAddress),
		context->usb_rx_buf, sizeof(context->usb_rx_buf),
		usb_rx_callback, context, context->rx_endpoint->bInterval);

	retval = usb_submit_urb(context->rx_urb, GFP_KERNEL);

	if (retval)
		dev_err(&context->dev->dev,
			"usb_submit_urb failed for ir_open (%d)\n", retval);
	else {
		context->ir_isopen = 1;
		dev_info(&context->dev->dev, "IR port opened\n");
	}

exit:
	mutex_unlock(&context->ctx_lock);

	mutex_unlock(&disconnect_lock);
	return retval;
}

/**
 * Called by lirc_dev when the application closes /dev/lirc
 */
static void ir_close(void *data)
{
	struct sasem_context *context;

	context = data;
	if (!context) {
		pr_err("%s: no context for device\n", __func__);
		return;
	}

	mutex_lock(&context->ctx_lock);

	usb_kill_urb(context->rx_urb);
	context->ir_isopen = 0;
	pr_info("IR port closed\n");

	if (!context->dev_present) {

		/*
		 * Device disconnected while IR port was
		 * still open. Driver was not deregistered
		 * at disconnect time, so do it now.
		 */
		deregister_from_lirc(context);

		if (!context->vfd_isopen) {

			mutex_unlock(&context->ctx_lock);
			delete_context(context);
			return;
		}
		/* If VFD port is open, context will be deleted by vfd_close */
	}

	mutex_unlock(&context->ctx_lock);
}

/**
 * Process the incoming packet
 */
static void incoming_packet(struct sasem_context *context,
				   struct urb *urb)
{
	int len = urb->actual_length;
	unsigned char *buf = urb->transfer_buffer;
	u64 ns;
	ktime_t kt;

	if (len != 8) {
		dev_warn(&context->dev->dev,
			 "%s: invalid incoming packet size (%d)\n",
			 __func__, len);
		return;
	}

	if (debug)
		dev_info(&context->dev->dev, "Incoming data: %*ph\n", len, buf);
	/*
	 * Lirc could deal with the repeat code, but we really need to block it
	 * if it arrives too late.  Otherwise we could repeat the wrong code.
	 */

	/* get the time since the last button press */
	kt = ktime_get();
	ns = ktime_to_ns(ktime_sub(kt, context->presstime));

	if (memcmp(buf, "\x08\0\0\0\0\0\0\0", 8) == 0) {
		/*
		 * the repeat code is being sent, so we copy
		 * the old code to LIRC
		 */

		/*
		 * NOTE: Only if the last code was less than 250ms ago
		 * - no one should be able to push another (undetected) button
		 *   in that time and then get a false repeat of the previous
		 *   press but it is long enough for a genuine repeat
		 */
		if ((ns < 250 * NSEC_PER_MSEC) && (context->codesaved != 0)) {
			memcpy(buf, &context->lastcode, 8);
			context->presstime = kt;
		}
	} else {
		/* save the current valid code for repeats */
		memcpy(&context->lastcode, buf, 8);
		/*
		 * set flag to signal a valid code was save;
		 * just for safety reasons
		 */
		context->codesaved = 1;
		context->presstime = kt;
	}

	lirc_buffer_write(context->driver->rbuf, buf);
	wake_up(&context->driver->rbuf->wait_poll);
}

/**
 * Callback function for USB core API: receive data
 */
static void usb_rx_callback(struct urb *urb)
{
	struct sasem_context *context;

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

	switch (urb->status) {

	case -ENOENT:		/* usbcore unlink successful! */
		return;

	case 0:
		if (context->ir_isopen)
			incoming_packet(context, urb);
		break;

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

	usb_submit_urb(context->rx_urb, GFP_ATOMIC);
}


/**
 * Callback function for USB core API: Probe
 */
static int sasem_probe(struct usb_interface *interface,
			const struct usb_device_id *id)
{
	struct usb_device *dev = NULL;
	struct usb_host_interface *iface_desc = NULL;
	struct usb_endpoint_descriptor *rx_endpoint = NULL;
	struct usb_endpoint_descriptor *tx_endpoint = NULL;
	struct urb *rx_urb = NULL;
	struct urb *tx_urb = NULL;
	struct lirc_driver *driver = NULL;
	struct lirc_buffer *rbuf = NULL;
	int lirc_minor = 0;
	int num_endpoints;
	int retval = 0;
	int vfd_ep_found;
	int ir_ep_found;
	int alloc_status;
	struct sasem_context *context = NULL;
	int i;

	dev_info(&interface->dev, "%s: found Sasem device\n", __func__);


	dev = usb_get_dev(interface_to_usbdev(interface));
	iface_desc = interface->cur_altsetting;
	num_endpoints = iface_desc->desc.bNumEndpoints;

	/*
	 * Scan the endpoint list and set:
	 *	first input endpoint = IR endpoint
	 *	first output endpoint = VFD endpoint
	 */

	ir_ep_found = 0;
	vfd_ep_found = 0;

	for (i = 0; i < num_endpoints && !(ir_ep_found && vfd_ep_found); ++i) {

		struct usb_endpoint_descriptor *ep;

		ep = &iface_desc->endpoint [i].desc;

		if (!ir_ep_found &&
			usb_endpoint_is_int_in(ep)) {

			rx_endpoint = ep;
			ir_ep_found = 1;
			if (debug)
				dev_info(&interface->dev,
					"%s: found IR endpoint\n", __func__);

		} else if (!vfd_ep_found &&
			usb_endpoint_is_int_out(ep)) {

			tx_endpoint = ep;
			vfd_ep_found = 1;
			if (debug)
				dev_info(&interface->dev,
					"%s: found VFD endpoint\n", __func__);
		}
	}

	/* Input endpoint is mandatory */
	if (!ir_ep_found) {
		dev_err(&interface->dev,
			"%s: no valid input (IR) endpoint found.\n", __func__);
		retval = -ENODEV;
		goto exit;
	}

	if (!vfd_ep_found)
		dev_info(&interface->dev,
			"%s: no valid output (VFD) endpoint found.\n",
			__func__);


	/* Allocate memory */
	alloc_status = 0;

	context = kzalloc(sizeof(struct sasem_context), GFP_KERNEL);
	if (!context) {
		alloc_status = 1;
		goto alloc_status_switch;
	}
	driver = kzalloc(sizeof(struct lirc_driver), GFP_KERNEL);
	if (!driver) {
		alloc_status = 2;
		goto alloc_status_switch;
	}
	rbuf = kmalloc(sizeof(struct lirc_buffer), GFP_KERNEL);
	if (!rbuf) {
		alloc_status = 3;
		goto alloc_status_switch;
	}
	if (lirc_buffer_init(rbuf, BUF_CHUNK_SIZE, BUF_SIZE)) {
		dev_err(&interface->dev,
			"%s: lirc_buffer_init failed\n", __func__);
		alloc_status = 4;
		goto alloc_status_switch;
	}
	rx_urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!rx_urb) {
		dev_err(&interface->dev,
			"%s: usb_alloc_urb failed for IR urb\n", __func__);
		alloc_status = 5;
		goto alloc_status_switch;
	}
	if (vfd_ep_found) {
		tx_urb = usb_alloc_urb(0, GFP_KERNEL);
		if (!tx_urb) {
			dev_err(&interface->dev,
				"%s: usb_alloc_urb failed for VFD urb",
				__func__);
			alloc_status = 6;
			goto alloc_status_switch;
		}
	}

	mutex_init(&context->ctx_lock);

	strcpy(driver->name, MOD_NAME);
	driver->minor = -1;
	driver->code_length = 64;
	driver->sample_rate = 0;
	driver->features = LIRC_CAN_REC_LIRCCODE;
	driver->data = context;
	driver->rbuf = rbuf;
	driver->set_use_inc = ir_open;
	driver->set_use_dec = ir_close;
	driver->dev   = &interface->dev;
	driver->owner = THIS_MODULE;

	mutex_lock(&context->ctx_lock);

	lirc_minor = lirc_register_driver(driver);
	if (lirc_minor < 0) {
		dev_err(&interface->dev,
			"%s: lirc_register_driver failed\n", __func__);
		alloc_status = 7;
		retval = lirc_minor;
		goto unlock;
	} else
		dev_info(&interface->dev,
			 "%s: Registered Sasem driver (minor:%d)\n",
			 __func__, lirc_minor);

	/* Needed while unregistering! */
	driver->minor = lirc_minor;

	context->dev = dev;
	context->dev_present = 1;
	context->rx_endpoint = rx_endpoint;
	context->rx_urb = rx_urb;
	if (vfd_ep_found) {
		context->tx_endpoint = tx_endpoint;
		context->tx_urb = tx_urb;
		context->vfd_contrast = 1000;   /* range 0 - 1000 */
	}
	context->driver = driver;

	usb_set_intfdata(interface, context);

	if (vfd_ep_found) {

		if (debug)
			dev_info(&interface->dev,
				 "Registering VFD with sysfs\n");
		if (usb_register_dev(interface, &sasem_class))
			/* Not a fatal error, so ignore */
			dev_info(&interface->dev,
				 "%s: could not get a minor number for VFD\n",
				 __func__);
	}

	dev_info(&interface->dev,
		 "%s: Sasem device on usb<%d:%d> initialized\n",
		 __func__, dev->bus->busnum, dev->devnum);
unlock:
	mutex_unlock(&context->ctx_lock);

alloc_status_switch:
	switch (alloc_status) {

	case 7:
		if (vfd_ep_found)
			usb_free_urb(tx_urb);
	case 6:
		usb_free_urb(rx_urb);
		/* fall-through */
	case 5:
		lirc_buffer_free(rbuf);
		/* fall-through */
	case 4:
		kfree(rbuf);
		/* fall-through */
	case 3:
		kfree(driver);
		/* fall-through */
	case 2:
		kfree(context);
		context = NULL;
		/* fall-through */
	case 1:
		if (retval == 0)
			retval = -ENOMEM;
	}

exit:
	return retval;
}

/**
 * Callback function for USB core API: disconnect
 */
static void sasem_disconnect(struct usb_interface *interface)
{
	struct sasem_context *context;

	/* prevent races with ir_open()/vfd_open() */
	mutex_lock(&disconnect_lock);

	context = usb_get_intfdata(interface);
	mutex_lock(&context->ctx_lock);

	dev_info(&interface->dev, "%s: Sasem device disconnected\n",
		 __func__);

	usb_set_intfdata(interface, NULL);
	context->dev_present = 0;

	/* Stop reception */
	usb_kill_urb(context->rx_urb);

	/* Abort ongoing write */
	if (atomic_read(&context->tx.busy)) {

		usb_kill_urb(context->tx_urb);
		wait_for_completion(&context->tx.finished);
	}

	/* De-register from lirc_dev if IR port is not open */
	if (!context->ir_isopen)
		deregister_from_lirc(context);

	usb_deregister_dev(interface, &sasem_class);

	mutex_unlock(&context->ctx_lock);

	if (!context->ir_isopen && !context->vfd_isopen)
		delete_context(context);

	mutex_unlock(&disconnect_lock);
}

module_usb_driver(sasem_driver);