drivers/usb/misc/appledisplay.c - arm/linux-arm64-legacy - Git at Google

 /*
  * Apple Cinema Display driver
  *
  * Copyright (C) 2006  Michael Hanselmann (linux-kernel@hansmi.ch)
  *
  * Thanks to Caskey L. Dickson for his work with acdctl.
  *
  * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */

 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/usb.h>
 #include <linux/backlight.h>
 #include <linux/timer.h>
 #include <linux/workqueue.h>
 #include <linux/atomic.h>

 #define APPLE_VENDOR_ID		0x05AC

 #define USB_REQ_GET_REPORT	0x01
 #define USB_REQ_SET_REPORT	0x09

 #define ACD_USB_TIMEOUT		250

 #define ACD_USB_EDID		0x0302
 #define ACD_USB_BRIGHTNESS	0x0310

 #define ACD_BTN_NONE		0
 #define ACD_BTN_BRIGHT_UP	3
 #define ACD_BTN_BRIGHT_DOWN	4

 #define ACD_URB_BUFFER_LEN	2
 #define ACD_MSG_BUFFER_LEN	2

 #define APPLEDISPLAY_DEVICE(prod)				\
 	.match_flags = USB_DEVICE_ID_MATCH_DEVICE |		\
 		       USB_DEVICE_ID_MATCH_INT_CLASS |		\
 		       USB_DEVICE_ID_MATCH_INT_PROTOCOL,	\
 	.idVendor = APPLE_VENDOR_ID,				\
 	.idProduct = (prod),					\
 	.bInterfaceClass = USB_CLASS_HID,			\
 	.bInterfaceProtocol = 0x00

 /* table of devices that work with this driver */
 static const struct usb_device_id appledisplay_table[] = {
 	{ APPLEDISPLAY_DEVICE(0x9218) },
 	{ APPLEDISPLAY_DEVICE(0x9219) },
 	{ APPLEDISPLAY_DEVICE(0x921c) },
 	{ APPLEDISPLAY_DEVICE(0x921d) },
 	{ APPLEDISPLAY_DEVICE(0x9236) },

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

 /* Structure to hold all of our device specific stuff */
 struct appledisplay {
 	struct usb_device *udev;	/* usb device */
 	struct urb *urb;		/* usb request block */
 	struct backlight_device *bd;	/* backlight device */
 	u8 *urbdata;			/* interrupt URB data buffer */
 	u8 *msgdata;			/* control message data buffer */

 	struct delayed_work work;
 	int button_pressed;
 	spinlock_t lock;
 	struct mutex sysfslock;		/* concurrent read and write */
 };

 static atomic_t count_displays = ATOMIC_INIT(0);
 static struct workqueue_struct *wq;

 static void appledisplay_complete(struct urb *urb)
 {
 	struct appledisplay *pdata = urb->context;
 	struct device *dev = &pdata->udev->dev;
 	unsigned long flags;
 	int status = urb->status;
 	int retval;

 	switch (status) {
 	case 0:
 		/* success */
 		break;
 	case -EOVERFLOW:
 		dev_err(dev,
 			"OVERFLOW with data length %d, actual length is %d\n",
 			ACD_URB_BUFFER_LEN, pdata->urb->actual_length);
 	case -ECONNRESET:
 	case -ENOENT:
 	case -ESHUTDOWN:
 		/* This urb is terminated, clean up */
 		dev_dbg(dev, "%s - urb shuttingdown with status: %d\n",
 			__func__, status);
 		return;
 	default:
 		dev_dbg(dev, "%s - nonzero urb status received: %d\n",
 			__func__, status);
 		goto exit;
 	}

 	spin_lock_irqsave(&pdata->lock, flags);

 	switch(pdata->urbdata[1]) {
 	case ACD_BTN_BRIGHT_UP:
 	case ACD_BTN_BRIGHT_DOWN:
 		pdata->button_pressed = 1;
 		queue_delayed_work(wq, &pdata->work, 0);
 		break;
 	case ACD_BTN_NONE:
 	default:
 		pdata->button_pressed = 0;
 		break;
 	}

 	spin_unlock_irqrestore(&pdata->lock, flags);

 exit:
 	retval = usb_submit_urb(pdata->urb, GFP_ATOMIC);
 	if (retval) {
 		dev_err(dev, "%s - usb_submit_urb failed with result %d\n",
 			__func__, retval);
 	}
 }

 static int appledisplay_bl_update_status(struct backlight_device *bd)
 {
 	struct appledisplay *pdata = bl_get_data(bd);
 	int retval;

 	mutex_lock(&pdata->sysfslock);
 	pdata->msgdata[0] = 0x10;
 	pdata->msgdata[1] = bd->props.brightness;

 	retval = usb_control_msg(
 		pdata->udev,
 		usb_sndctrlpipe(pdata->udev, 0),
 		USB_REQ_SET_REPORT,
 		USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 		ACD_USB_BRIGHTNESS,
 		0,
 		pdata->msgdata, 2,
 		ACD_USB_TIMEOUT);
 	mutex_unlock(&pdata->sysfslock);

 	return retval;
 }

 static int appledisplay_bl_get_brightness(struct backlight_device *bd)
 {
 	struct appledisplay *pdata = bl_get_data(bd);
 	int retval, brightness;

 	mutex_lock(&pdata->sysfslock);
 	retval = usb_control_msg(
 		pdata->udev,
 		usb_rcvctrlpipe(pdata->udev, 0),
 		USB_REQ_GET_REPORT,
 		USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 		ACD_USB_BRIGHTNESS,
 		0,
 		pdata->msgdata, 2,
 		ACD_USB_TIMEOUT);
 	brightness = pdata->msgdata[1];
 	mutex_unlock(&pdata->sysfslock);

 	if (retval < 0)
 		return retval;
 	else
 		return brightness;
 }

 static const struct backlight_ops appledisplay_bl_data = {
 	.get_brightness	= appledisplay_bl_get_brightness,
 	.update_status	= appledisplay_bl_update_status,
 };

 static void appledisplay_work(struct work_struct *work)
 {
 	struct appledisplay *pdata =
 		container_of(work, struct appledisplay, work.work);
 	int retval;

 	retval = appledisplay_bl_get_brightness(pdata->bd);
 	if (retval >= 0)
 		pdata->bd->props.brightness = retval;

 	/* Poll again in about 125ms if there's still a button pressed */
 	if (pdata->button_pressed)
 		schedule_delayed_work(&pdata->work, HZ / 8);
 }

 static int appledisplay_probe(struct usb_interface *iface,
 	const struct usb_device_id *id)
 {
 	struct backlight_properties props;
 	struct appledisplay *pdata;
 	struct usb_device *udev = interface_to_usbdev(iface);
 	struct usb_host_interface *iface_desc;
 	struct usb_endpoint_descriptor *endpoint;
 	int int_in_endpointAddr = 0;
 	int i, retval = -ENOMEM, brightness;
 	char bl_name[20];

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

 	/* allocate memory for our device state and initialize it */
 	pdata = kzalloc(sizeof(struct appledisplay), GFP_KERNEL);
 	if (!pdata) {
 		retval = -ENOMEM;
 		dev_err(&iface->dev, "Out of memory\n");
 		goto error;
 	}

 	pdata->udev = udev;

 	spin_lock_init(&pdata->lock);
 	INIT_DELAYED_WORK(&pdata->work, appledisplay_work);
 	mutex_init(&pdata->sysfslock);

 	/* Allocate buffer for control messages */
 	pdata->msgdata = kmalloc(ACD_MSG_BUFFER_LEN, GFP_KERNEL);
 	if (!pdata->msgdata) {
 		retval = -ENOMEM;
 		dev_err(&iface->dev,
 			"Allocating buffer for control messages failed\n");
 		goto error;
 	}

 	/* Allocate interrupt URB */
 	pdata->urb = usb_alloc_urb(0, GFP_KERNEL);
 	if (!pdata->urb) {
 		retval = -ENOMEM;
 		dev_err(&iface->dev, "Allocating URB failed\n");
 		goto error;
 	}

 	/* Allocate buffer for interrupt data */
 	pdata->urbdata = usb_alloc_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
 		GFP_KERNEL, &pdata->urb->transfer_dma);
 	if (!pdata->urbdata) {
 		retval = -ENOMEM;
 		dev_err(&iface->dev, "Allocating URB buffer failed\n");
 		goto error;
 	}

 	/* Configure interrupt URB */
 	usb_fill_int_urb(pdata->urb, udev,
 		usb_rcvintpipe(udev, int_in_endpointAddr),
 		pdata->urbdata, ACD_URB_BUFFER_LEN, appledisplay_complete,
 		pdata, 1);
 	if (usb_submit_urb(pdata->urb, GFP_KERNEL)) {
 		retval = -EIO;
 		dev_err(&iface->dev, "Submitting URB failed\n");
 		goto error;
 	}

 	/* Register backlight device */
 	snprintf(bl_name, sizeof(bl_name), "appledisplay%d",
 		atomic_inc_return(&count_displays) - 1);
 	memset(&props, 0, sizeof(struct backlight_properties));
 	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	pdata->bd = backlight_device_register(bl_name, NULL, pdata,
 					      &appledisplay_bl_data, &props);
 	if (IS_ERR(pdata->bd)) {
 		dev_err(&iface->dev, "Backlight registration failed\n");
 		retval = PTR_ERR(pdata->bd);
 		goto error;
 	}

 	/* Try to get brightness */
 	brightness = appledisplay_bl_get_brightness(pdata->bd);

 	if (brightness < 0) {
 		retval = brightness;
 		dev_err(&iface->dev,
 			"Error while getting initial brightness: %d\n", retval);
 		goto error;
 	}

 	/* Set brightness in backlight device */
 	pdata->bd->props.brightness = brightness;

 	/* save our data pointer in the interface device */
 	usb_set_intfdata(iface, pdata);

 	printk(KERN_INFO "appledisplay: Apple Cinema Display connected\n");

 	return 0;

 error:
 	if (pdata) {
 		if (pdata->urb) {
 			usb_kill_urb(pdata->urb);
 			if (pdata->urbdata)
 				usb_free_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
 					pdata->urbdata, pdata->urb->transfer_dma);
 			usb_free_urb(pdata->urb);
 		}
 		if (pdata->bd && !IS_ERR(pdata->bd))
 			backlight_device_unregister(pdata->bd);
 		kfree(pdata->msgdata);
 	}
 	usb_set_intfdata(iface, NULL);
 	kfree(pdata);
 	return retval;
 }

 static void appledisplay_disconnect(struct usb_interface *iface)
 {
 	struct appledisplay *pdata = usb_get_intfdata(iface);

 	if (pdata) {
 		usb_kill_urb(pdata->urb);
 		cancel_delayed_work(&pdata->work);
 		backlight_device_unregister(pdata->bd);
 		usb_free_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
 			pdata->urbdata, pdata->urb->transfer_dma);
 		usb_free_urb(pdata->urb);
 		kfree(pdata->msgdata);
 		kfree(pdata);
 	}

 	printk(KERN_INFO "appledisplay: Apple Cinema Display disconnected\n");
 }

 static struct usb_driver appledisplay_driver = {
 	.name		= "appledisplay",
 	.probe		= appledisplay_probe,
 	.disconnect	= appledisplay_disconnect,
 	.id_table	= appledisplay_table,
 };

 static int __init appledisplay_init(void)
 {
 	wq = create_singlethread_workqueue("appledisplay");
 	if (!wq) {
 		printk(KERN_ERR "appledisplay: Could not create work queue\n");
 		return -ENOMEM;
 	}

 	return usb_register(&appledisplay_driver);
 }

 static void __exit appledisplay_exit(void)
 {
 	flush_workqueue(wq);
 	destroy_workqueue(wq);
 	usb_deregister(&appledisplay_driver);
 }

 MODULE_AUTHOR("Michael Hanselmann");
 MODULE_DESCRIPTION("Apple Cinema Display driver");
 MODULE_LICENSE("GPL");

 module_init(appledisplay_init);
 module_exit(appledisplay_exit);
	/*
	* Apple Cinema Display driver
	*
	* Copyright (C) 2006 Michael Hanselmann (linux-kernel@hansmi.ch)
	*
	* Thanks to Caskey L. Dickson for his work with acdctl.
	*
	* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
	*/

	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/usb.h>
	#include <linux/backlight.h>
	#include <linux/timer.h>
	#include <linux/workqueue.h>
	#include <linux/atomic.h>

	#define APPLE_VENDOR_ID 0x05AC

	#define USB_REQ_GET_REPORT 0x01
	#define USB_REQ_SET_REPORT 0x09

	#define ACD_USB_TIMEOUT 250

	#define ACD_USB_EDID 0x0302
	#define ACD_USB_BRIGHTNESS 0x0310

	#define ACD_BTN_NONE 0
	#define ACD_BTN_BRIGHT_UP 3
	#define ACD_BTN_BRIGHT_DOWN 4

	#define ACD_URB_BUFFER_LEN 2
	#define ACD_MSG_BUFFER_LEN 2

	#define APPLEDISPLAY_DEVICE(prod) \
	.match_flags = USB_DEVICE_ID_MATCH_DEVICE \| \
	USB_DEVICE_ID_MATCH_INT_CLASS \| \
	USB_DEVICE_ID_MATCH_INT_PROTOCOL, \
	.idVendor = APPLE_VENDOR_ID, \
	.idProduct = (prod), \
	.bInterfaceClass = USB_CLASS_HID, \
	.bInterfaceProtocol = 0x00

	/* table of devices that work with this driver */
	static const struct usb_device_id appledisplay_table[] = {
	{ APPLEDISPLAY_DEVICE(0x9218) },
	{ APPLEDISPLAY_DEVICE(0x9219) },
	{ APPLEDISPLAY_DEVICE(0x921c) },
	{ APPLEDISPLAY_DEVICE(0x921d) },
	{ APPLEDISPLAY_DEVICE(0x9236) },

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

	/* Structure to hold all of our device specific stuff */
	struct appledisplay {
	struct usb_device udev; / usb device */
	struct urb urb; / usb request block */
	struct backlight_device bd; / backlight device */
	u8 urbdata; / interrupt URB data buffer */
	u8 msgdata; / control message data buffer */

	struct delayed_work work;
	int button_pressed;
	spinlock_t lock;
	struct mutex sysfslock; /* concurrent read and write */
	};

	static atomic_t count_displays = ATOMIC_INIT(0);
	static struct workqueue_struct *wq;

	static void appledisplay_complete(struct urb *urb)
	{
	struct appledisplay *pdata = urb->context;
	struct device *dev = &pdata->udev->dev;
	unsigned long flags;
	int status = urb->status;
	int retval;

	switch (status) {
	case 0:
	/* success */
	break;
	case -EOVERFLOW:
	dev_err(dev,
	"OVERFLOW with data length %d, actual length is %d\n",
	ACD_URB_BUFFER_LEN, pdata->urb->actual_length);
	case -ECONNRESET:
	case -ENOENT:
	case -ESHUTDOWN:
	/* This urb is terminated, clean up */
	dev_dbg(dev, "%s - urb shuttingdown with status: %d\n",
	__func__, status);
	return;
	default:
	dev_dbg(dev, "%s - nonzero urb status received: %d\n",
	__func__, status);
	goto exit;
	}

	spin_lock_irqsave(&pdata->lock, flags);

	switch(pdata->urbdata[1]) {
	case ACD_BTN_BRIGHT_UP:
	case ACD_BTN_BRIGHT_DOWN:
	pdata->button_pressed = 1;
	queue_delayed_work(wq, &pdata->work, 0);
	break;
	case ACD_BTN_NONE:
	default:
	pdata->button_pressed = 0;
	break;
	}

	spin_unlock_irqrestore(&pdata->lock, flags);

	exit:
	retval = usb_submit_urb(pdata->urb, GFP_ATOMIC);
	if (retval) {
	dev_err(dev, "%s - usb_submit_urb failed with result %d\n",
	__func__, retval);
	}
	}

	static int appledisplay_bl_update_status(struct backlight_device *bd)
	{
	struct appledisplay *pdata = bl_get_data(bd);
	int retval;

	mutex_lock(&pdata->sysfslock);
	pdata->msgdata[0] = 0x10;
	pdata->msgdata[1] = bd->props.brightness;

	retval = usb_control_msg(
	pdata->udev,
	usb_sndctrlpipe(pdata->udev, 0),
	USB_REQ_SET_REPORT,
	USB_DIR_OUT \| USB_TYPE_CLASS \| USB_RECIP_INTERFACE,
	ACD_USB_BRIGHTNESS,
	0,
	pdata->msgdata, 2,
	ACD_USB_TIMEOUT);
	mutex_unlock(&pdata->sysfslock);

	return retval;
	}

	static int appledisplay_bl_get_brightness(struct backlight_device *bd)
	{
	struct appledisplay *pdata = bl_get_data(bd);
	int retval, brightness;

	mutex_lock(&pdata->sysfslock);
	retval = usb_control_msg(
	pdata->udev,
	usb_rcvctrlpipe(pdata->udev, 0),
	USB_REQ_GET_REPORT,
	USB_DIR_IN \| USB_TYPE_CLASS \| USB_RECIP_INTERFACE,
	ACD_USB_BRIGHTNESS,
	0,
	pdata->msgdata, 2,
	ACD_USB_TIMEOUT);
	brightness = pdata->msgdata[1];
	mutex_unlock(&pdata->sysfslock);

	if (retval < 0)
	return retval;
	else
	return brightness;
	}

	static const struct backlight_ops appledisplay_bl_data = {
	.get_brightness = appledisplay_bl_get_brightness,
	.update_status = appledisplay_bl_update_status,
	};

	static void appledisplay_work(struct work_struct *work)
	{
	struct appledisplay *pdata =
	container_of(work, struct appledisplay, work.work);
	int retval;

	retval = appledisplay_bl_get_brightness(pdata->bd);
	if (retval >= 0)
	pdata->bd->props.brightness = retval;

	/* Poll again in about 125ms if there's still a button pressed */
	if (pdata->button_pressed)
	schedule_delayed_work(&pdata->work, HZ / 8);
	}

	static int appledisplay_probe(struct usb_interface *iface,
	const struct usb_device_id *id)
	{
	struct backlight_properties props;
	struct appledisplay *pdata;
	struct usb_device *udev = interface_to_usbdev(iface);
	struct usb_host_interface *iface_desc;
	struct usb_endpoint_descriptor *endpoint;
	int int_in_endpointAddr = 0;
	int i, retval = -ENOMEM, brightness;
	char bl_name[20];

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

	/* allocate memory for our device state and initialize it */
	pdata = kzalloc(sizeof(struct appledisplay), GFP_KERNEL);
	if (!pdata) {
	retval = -ENOMEM;
	dev_err(&iface->dev, "Out of memory\n");
	goto error;
	}

	pdata->udev = udev;

	spin_lock_init(&pdata->lock);
	INIT_DELAYED_WORK(&pdata->work, appledisplay_work);
	mutex_init(&pdata->sysfslock);

	/* Allocate buffer for control messages */
	pdata->msgdata = kmalloc(ACD_MSG_BUFFER_LEN, GFP_KERNEL);
	if (!pdata->msgdata) {
	retval = -ENOMEM;
	dev_err(&iface->dev,
	"Allocating buffer for control messages failed\n");
	goto error;
	}

	/* Allocate interrupt URB */
	pdata->urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!pdata->urb) {
	retval = -ENOMEM;
	dev_err(&iface->dev, "Allocating URB failed\n");
	goto error;
	}

	/* Allocate buffer for interrupt data */
	pdata->urbdata = usb_alloc_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
	GFP_KERNEL, &pdata->urb->transfer_dma);
	if (!pdata->urbdata) {
	retval = -ENOMEM;
	dev_err(&iface->dev, "Allocating URB buffer failed\n");
	goto error;
	}

	/* Configure interrupt URB */
	usb_fill_int_urb(pdata->urb, udev,
	usb_rcvintpipe(udev, int_in_endpointAddr),
	pdata->urbdata, ACD_URB_BUFFER_LEN, appledisplay_complete,
	pdata, 1);
	if (usb_submit_urb(pdata->urb, GFP_KERNEL)) {
	retval = -EIO;
	dev_err(&iface->dev, "Submitting URB failed\n");
	goto error;
	}

	/* Register backlight device */
	snprintf(bl_name, sizeof(bl_name), "appledisplay%d",
	atomic_inc_return(&count_displays) - 1);
	memset(&props, 0, sizeof(struct backlight_properties));
	props.type = BACKLIGHT_RAW;
	props.max_brightness = 0xff;
	pdata->bd = backlight_device_register(bl_name, NULL, pdata,
	&appledisplay_bl_data, &props);
	if (IS_ERR(pdata->bd)) {
	dev_err(&iface->dev, "Backlight registration failed\n");
	retval = PTR_ERR(pdata->bd);
	goto error;
	}

	/* Try to get brightness */
	brightness = appledisplay_bl_get_brightness(pdata->bd);

	if (brightness < 0) {
	retval = brightness;
	dev_err(&iface->dev,
	"Error while getting initial brightness: %d\n", retval);
	goto error;
	}

	/* Set brightness in backlight device */
	pdata->bd->props.brightness = brightness;

	/* save our data pointer in the interface device */
	usb_set_intfdata(iface, pdata);

	printk(KERN_INFO "appledisplay: Apple Cinema Display connected\n");

	return 0;

	error:
	if (pdata) {
	if (pdata->urb) {
	usb_kill_urb(pdata->urb);
	if (pdata->urbdata)
	usb_free_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
	pdata->urbdata, pdata->urb->transfer_dma);
	usb_free_urb(pdata->urb);
	}
	if (pdata->bd && !IS_ERR(pdata->bd))
	backlight_device_unregister(pdata->bd);
	kfree(pdata->msgdata);
	}
	usb_set_intfdata(iface, NULL);
	kfree(pdata);
	return retval;
	}

	static void appledisplay_disconnect(struct usb_interface *iface)
	{
	struct appledisplay *pdata = usb_get_intfdata(iface);

	if (pdata) {
	usb_kill_urb(pdata->urb);
	cancel_delayed_work(&pdata->work);
	backlight_device_unregister(pdata->bd);
	usb_free_coherent(pdata->udev, ACD_URB_BUFFER_LEN,
	pdata->urbdata, pdata->urb->transfer_dma);
	usb_free_urb(pdata->urb);
	kfree(pdata->msgdata);
	kfree(pdata);
	}

	printk(KERN_INFO "appledisplay: Apple Cinema Display disconnected\n");
	}

	static struct usb_driver appledisplay_driver = {
	.name = "appledisplay",
	.probe = appledisplay_probe,
	.disconnect = appledisplay_disconnect,
	.id_table = appledisplay_table,
	};

	static int __init appledisplay_init(void)
	{
	wq = create_singlethread_workqueue("appledisplay");
	if (!wq) {
	printk(KERN_ERR "appledisplay: Could not create work queue\n");
	return -ENOMEM;
	}

	return usb_register(&appledisplay_driver);
	}

	static void __exit appledisplay_exit(void)
	{
	flush_workqueue(wq);
	destroy_workqueue(wq);
	usb_deregister(&appledisplay_driver);
	}

	MODULE_AUTHOR("Michael Hanselmann");
	MODULE_DESCRIPTION("Apple Cinema Display driver");
	MODULE_LICENSE("GPL");

	module_init(appledisplay_init);
	module_exit(appledisplay_exit);