[mirror_ubuntu-artful-kernel.git] / drivers / usb / misc / chaoskey.c

/*
 * chaoskey - driver for ChaosKey device from Altus Metrum.
 *
 * This device provides true random numbers using a noise source based
 * on a reverse-biased p-n junction in avalanche breakdown. More
 * details can be found at http://chaoskey.org
 *
 * The driver connects to the kernel hardware RNG interface to provide
 * entropy for /dev/random and other kernel activities. It also offers
 * a separate /dev/ entry to allow for direct access to the random
 * bit stream.
 *
 * Copyright © 2015 Keith Packard <keithp@keithp.com>
 *
 * 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; version 2 of the License.
 *
 * 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.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/wait.h>
#include <linux/hw_random.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>

static struct usb_driver chaoskey_driver;
static struct usb_class_driver chaoskey_class;
static int chaoskey_rng_read(struct hwrng *rng, void *data,
			     size_t max, bool wait);

#define usb_dbg(usb_if, format, arg...) \
	dev_dbg(&(usb_if)->dev, format, ## arg)

#define usb_err(usb_if, format, arg...) \
	dev_err(&(usb_if)->dev, format, ## arg)

/* Version Information */
#define DRIVER_VERSION	"v0.1"
#define DRIVER_AUTHOR	"Keith Packard, keithp@keithp.com"
#define DRIVER_DESC	"Altus Metrum ChaosKey driver"
#define DRIVER_SHORT	"chaoskey"

MODULE_VERSION(DRIVER_VERSION);
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

#define CHAOSKEY_VENDOR_ID	0x1d50	/* OpenMoko */
#define CHAOSKEY_PRODUCT_ID	0x60c6	/* ChaosKey */

#define ALEA_VENDOR_ID		0x12d8	/* Araneus */
#define ALEA_PRODUCT_ID		0x0001	/* Alea I */

#define CHAOSKEY_BUF_LEN	64	/* max size of USB full speed packet */

#define NAK_TIMEOUT (HZ)		/* normal stall/wait timeout */
#define ALEA_FIRST_TIMEOUT (HZ*3)	/* first stall/wait timeout for Alea */

#ifdef CONFIG_USB_DYNAMIC_MINORS
#define USB_CHAOSKEY_MINOR_BASE 0
#else

/* IOWARRIOR_MINOR_BASE + 16, not official yet */
#define USB_CHAOSKEY_MINOR_BASE 224
#endif

static const struct usb_device_id chaoskey_table[] = {
	{ USB_DEVICE(CHAOSKEY_VENDOR_ID, CHAOSKEY_PRODUCT_ID) },
	{ USB_DEVICE(ALEA_VENDOR_ID, ALEA_PRODUCT_ID) },
	{ },
};
MODULE_DEVICE_TABLE(usb, chaoskey_table);

static void chaos_read_callback(struct urb *urb);

/* Driver-local specific stuff */
struct chaoskey {
	struct usb_interface *interface;
	char in_ep;
	struct mutex lock;
	struct mutex rng_lock;
	int open;			/* open count */
	bool present;			/* device not disconnected */
	bool reading;			/* ongoing IO */
	bool reads_started;		/* track first read for Alea */
	int size;			/* size of buf */
	int valid;			/* bytes of buf read */
	int used;			/* bytes of buf consumed */
	char *name;			/* product + serial */
	struct hwrng hwrng;		/* Embedded struct for hwrng */
	int hwrng_registered;		/* registered with hwrng API */
	wait_queue_head_t wait_q;	/* for timeouts */
	struct urb *urb;		/* for performing IO */
	char *buf;
};

static void chaoskey_free(struct chaoskey *dev)
{
	if (dev) {
		usb_dbg(dev->interface, "free");
		usb_free_urb(dev->urb);
		kfree(dev->name);
		kfree(dev->buf);
		kfree(dev);
	}
}

static int chaoskey_probe(struct usb_interface *interface,
			  const struct usb_device_id *id)
{
	struct usb_device *udev = interface_to_usbdev(interface);
	struct usb_host_interface *altsetting = interface->cur_altsetting;
	struct usb_endpoint_descriptor *epd;
	int in_ep;
	struct chaoskey *dev;
	int result = -ENOMEM;
	int size;
	int res;

	usb_dbg(interface, "probe %s-%s", udev->product, udev->serial);

	/* Find the first bulk IN endpoint and its packet size */
	res = usb_find_bulk_in_endpoint(altsetting, &epd);
	if (res) {
		usb_dbg(interface, "no IN endpoint found");
		return res;
	}

	in_ep = usb_endpoint_num(epd);
	size = usb_endpoint_maxp(epd);

	/* Validate endpoint and size */
	if (size <= 0) {
		usb_dbg(interface, "invalid size (%d)", size);
		return -ENODEV;
	}

	if (size > CHAOSKEY_BUF_LEN) {
		usb_dbg(interface, "size reduced from %d to %d\n",
			size, CHAOSKEY_BUF_LEN);
		size = CHAOSKEY_BUF_LEN;
	}

	/* Looks good, allocate and initialize */

	dev = kzalloc(sizeof(struct chaoskey), GFP_KERNEL);

	if (dev == NULL)
		goto out;

	dev->buf = kmalloc(size, GFP_KERNEL);

	if (dev->buf == NULL)
		goto out;

	dev->urb = usb_alloc_urb(0, GFP_KERNEL);

	if (!dev->urb)
		goto out;

	usb_fill_bulk_urb(dev->urb,
		udev,
		usb_rcvbulkpipe(udev, in_ep),
		dev->buf,
		size,
		chaos_read_callback,
		dev);

	/* Construct a name using the product and serial values. Each
	 * device needs a unique name for the hwrng code
	 */

	if (udev->product && udev->serial) {
		dev->name = kmalloc(strlen(udev->product) + 1 +
				    strlen(udev->serial) + 1, GFP_KERNEL);
		if (dev->name == NULL)
			goto out;

		strcpy(dev->name, udev->product);
		strcat(dev->name, "-");
		strcat(dev->name, udev->serial);
	}

	dev->interface = interface;

	dev->in_ep = in_ep;

	if (le16_to_cpu(udev->descriptor.idVendor) != ALEA_VENDOR_ID)
		dev->reads_started = 1;

	dev->size = size;
	dev->present = 1;

	init_waitqueue_head(&dev->wait_q);

	mutex_init(&dev->lock);
	mutex_init(&dev->rng_lock);

	usb_set_intfdata(interface, dev);

	result = usb_register_dev(interface, &chaoskey_class);
	if (result) {
		usb_err(interface, "Unable to allocate minor number.");
		goto out;
	}

	dev->hwrng.name = dev->name ? dev->name : chaoskey_driver.name;
	dev->hwrng.read = chaoskey_rng_read;
	dev->hwrng.quality = 1024;

	dev->hwrng_registered = (hwrng_register(&dev->hwrng) == 0);
	if (!dev->hwrng_registered)
		usb_err(interface, "Unable to register with hwrng");

	usb_enable_autosuspend(udev);

	usb_dbg(interface, "chaoskey probe success, size %d", dev->size);
	return 0;

out:
	usb_set_intfdata(interface, NULL);
	chaoskey_free(dev);
	return result;
}

static void chaoskey_disconnect(struct usb_interface *interface)
{
	struct chaoskey	*dev;

	usb_dbg(interface, "disconnect");
	dev = usb_get_intfdata(interface);
	if (!dev) {
		usb_dbg(interface, "disconnect failed - no dev");
		return;
	}

	if (dev->hwrng_registered)
		hwrng_unregister(&dev->hwrng);

	usb_deregister_dev(interface, &chaoskey_class);

	usb_set_intfdata(interface, NULL);
	mutex_lock(&dev->lock);

	dev->present = 0;
	usb_poison_urb(dev->urb);

	if (!dev->open) {
		mutex_unlock(&dev->lock);
		chaoskey_free(dev);
	} else
		mutex_unlock(&dev->lock);

	usb_dbg(interface, "disconnect done");
}

static int chaoskey_open(struct inode *inode, struct file *file)
{
	struct chaoskey *dev;
	struct usb_interface *interface;

	/* get the interface from minor number and driver information */
	interface = usb_find_interface(&chaoskey_driver, iminor(inode));
	if (!interface)
		return -ENODEV;

	usb_dbg(interface, "open");

	dev = usb_get_intfdata(interface);
	if (!dev) {
		usb_dbg(interface, "open (dev)");
		return -ENODEV;
	}

	file->private_data = dev;
	mutex_lock(&dev->lock);
	++dev->open;
	mutex_unlock(&dev->lock);

	usb_dbg(interface, "open success");
	return 0;
}

static int chaoskey_release(struct inode *inode, struct file *file)
{
	struct chaoskey *dev = file->private_data;
	struct usb_interface *interface;

	if (dev == NULL)
		return -ENODEV;

	interface = dev->interface;

	usb_dbg(interface, "release");

	mutex_lock(&dev->lock);

	usb_dbg(interface, "open count at release is %d", dev->open);

	if (dev->open <= 0) {
		usb_dbg(interface, "invalid open count (%d)", dev->open);
		mutex_unlock(&dev->lock);
		return -ENODEV;
	}

	--dev->open;

	if (!dev->present) {
		if (dev->open == 0) {
			mutex_unlock(&dev->lock);
			chaoskey_free(dev);
		} else
			mutex_unlock(&dev->lock);
	} else
		mutex_unlock(&dev->lock);

	usb_dbg(interface, "release success");
	return 0;
}

static void chaos_read_callback(struct urb *urb)
{
	struct chaoskey *dev = urb->context;
	int status = urb->status;

	usb_dbg(dev->interface, "callback status (%d)", status);

	if (status == 0)
		dev->valid = urb->actual_length;
	else
		dev->valid = 0;

	dev->used = 0;

	/* must be seen first before validity is announced */
	smp_wmb();

	dev->reading = false;
	wake_up(&dev->wait_q);
}

/* Fill the buffer. Called with dev->lock held
 */
static int _chaoskey_fill(struct chaoskey *dev)
{
	DEFINE_WAIT(wait);
	int result;
	bool started;

	usb_dbg(dev->interface, "fill");

	/* Return immediately if someone called before the buffer was
	 * empty */
	if (dev->valid != dev->used) {
		usb_dbg(dev->interface, "not empty yet (valid %d used %d)",
			dev->valid, dev->used);
		return 0;
	}

	/* Bail if the device has been removed */
	if (!dev->present) {
		usb_dbg(dev->interface, "device not present");
		return -ENODEV;
	}

	/* Make sure the device is awake */
	result = usb_autopm_get_interface(dev->interface);
	if (result) {
		usb_dbg(dev->interface, "wakeup failed (result %d)", result);
		return result;
	}

	dev->reading = true;
	result = usb_submit_urb(dev->urb, GFP_KERNEL);
	if (result < 0) {
		result = usb_translate_errors(result);
		dev->reading = false;
		goto out;
	}

	/* The first read on the Alea takes a little under 2 seconds.
	 * Reads after the first read take only a few microseconds
	 * though.  Presumably the entropy-generating circuit needs
	 * time to ramp up.  So, we wait longer on the first read.
	 */
	started = dev->reads_started;
	dev->reads_started = true;
	result = wait_event_interruptible_timeout(
		dev->wait_q,
		!dev->reading,
		(started ? NAK_TIMEOUT : ALEA_FIRST_TIMEOUT) );

	if (result < 0)
		goto out;

	if (result == 0)
		result = -ETIMEDOUT;
	else
		result = dev->valid;
out:
	/* Let the device go back to sleep eventually */
	usb_autopm_put_interface(dev->interface);

	usb_dbg(dev->interface, "read %d bytes", dev->valid);

	return result;
}

static ssize_t chaoskey_read(struct file *file,
			     char __user *buffer,
			     size_t count,
			     loff_t *ppos)
{
	struct chaoskey *dev;
	ssize_t read_count = 0;
	int this_time;
	int result = 0;
	unsigned long remain;

	dev = file->private_data;

	if (dev == NULL || !dev->present)
		return -ENODEV;

	usb_dbg(dev->interface, "read %zu", count);

	while (count > 0) {

		/* Grab the rng_lock briefly to ensure that the hwrng interface
		 * gets priority over other user access
		 */
		result = mutex_lock_interruptible(&dev->rng_lock);
		if (result)
			goto bail;
		mutex_unlock(&dev->rng_lock);

		result = mutex_lock_interruptible(&dev->lock);
		if (result)
			goto bail;
		if (dev->valid == dev->used) {
			result = _chaoskey_fill(dev);
			if (result < 0) {
				mutex_unlock(&dev->lock);
				goto bail;
			}
		}

		this_time = dev->valid - dev->used;
		if (this_time > count)
			this_time = count;

		remain = copy_to_user(buffer, dev->buf + dev->used, this_time);
		if (remain) {
			result = -EFAULT;

			/* Consume the bytes that were copied so we don't leak
			 * data to user space
			 */
			dev->used += this_time - remain;
			mutex_unlock(&dev->lock);
			goto bail;
		}

		count -= this_time;
		read_count += this_time;
		buffer += this_time;
		dev->used += this_time;
		mutex_unlock(&dev->lock);
	}
bail:
	if (read_count) {
		usb_dbg(dev->interface, "read %zu bytes", read_count);
		return read_count;
	}
	usb_dbg(dev->interface, "empty read, result %d", result);
	if (result == -ETIMEDOUT)
		result = -EAGAIN;
	return result;
}

static int chaoskey_rng_read(struct hwrng *rng, void *data,
			     size_t max, bool wait)
{
	struct chaoskey *dev = container_of(rng, struct chaoskey, hwrng);
	int this_time;

	usb_dbg(dev->interface, "rng_read max %zu wait %d", max, wait);

	if (!dev->present) {
		usb_dbg(dev->interface, "device not present");
		return 0;
	}

	/* Hold the rng_lock until we acquire the device lock so that
	 * this operation gets priority over other user access to the
	 * device
	 */
	mutex_lock(&dev->rng_lock);

	mutex_lock(&dev->lock);

	mutex_unlock(&dev->rng_lock);

	/* Try to fill the buffer if empty. It doesn't actually matter
	 * if _chaoskey_fill works; we'll just return zero bytes as
	 * the buffer will still be empty
	 */
	if (dev->valid == dev->used)
		(void) _chaoskey_fill(dev);

	this_time = dev->valid - dev->used;
	if (this_time > max)
		this_time = max;

	memcpy(data, dev->buf + dev->used, this_time);

	dev->used += this_time;

	mutex_unlock(&dev->lock);

	usb_dbg(dev->interface, "rng_read this_time %d\n", this_time);
	return this_time;
}

#ifdef CONFIG_PM
static int chaoskey_suspend(struct usb_interface *interface,
			    pm_message_t message)
{
	usb_dbg(interface, "suspend");
	return 0;
}

static int chaoskey_resume(struct usb_interface *interface)
{
	usb_dbg(interface, "resume");
	return 0;
}
#else
#define chaoskey_suspend NULL
#define chaoskey_resume NULL
#endif

/* file operation pointers */
static const struct file_operations chaoskey_fops = {
	.owner = THIS_MODULE,
	.read = chaoskey_read,
	.open = chaoskey_open,
	.release = chaoskey_release,
	.llseek = default_llseek,
};

/* class driver information */
static struct usb_class_driver chaoskey_class = {
	.name = "chaoskey%d",
	.fops = &chaoskey_fops,
	.minor_base = USB_CHAOSKEY_MINOR_BASE,
};

/* usb specific object needed to register this driver with the usb subsystem */
static struct usb_driver chaoskey_driver = {
	.name = DRIVER_SHORT,
	.probe = chaoskey_probe,
	.disconnect = chaoskey_disconnect,
	.suspend = chaoskey_suspend,
	.resume = chaoskey_resume,
	.reset_resume = chaoskey_resume,
	.id_table = chaoskey_table,
	.supports_autosuspend = 1,
};

module_usb_driver(chaoskey_driver);
Commit	Line	Data
66e3e591 KP	1	/*
	2	* chaoskey - driver for ChaosKey device from Altus Metrum.
	3	*
	4	* This device provides true random numbers using a noise source based
	5	* on a reverse-biased p-n junction in avalanche breakdown. More
	6	* details can be found at http://chaoskey.org
	7	*
	8	* The driver connects to the kernel hardware RNG interface to provide
	9	* entropy for /dev/random and other kernel activities. It also offers
	10	* a separate /dev/ entry to allow for direct access to the random
	11	* bit stream.
	12	*
	13	* Copyright © 2015 Keith Packard <keithp@keithp.com>
	14	*
	15	* This program is free software; you can redistribute it and/or modify
	16	* it under the terms of the GNU General Public License as published by
	17	* the Free Software Foundation; version 2 of the License.
	18	*
	19	* This program is distributed in the hope that it will be useful, but
	20	* WITHOUT ANY WARRANTY; without even the implied warranty of
	21	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	22	* General Public License for more details.
	23	*/
	24
	25	#include <linux/module.h>
	26	#include <linux/slab.h>
	27	#include <linux/usb.h>
	28	#include <linux/wait.h>
	29	#include <linux/hw_random.h>
8b86ed07 KP	30	#include <linux/mutex.h>
8b86ed07 KP	31	#include <linux/uaccess.h>
66e3e591 KP	32
	33	static struct usb_driver chaoskey_driver;
	34	static struct usb_class_driver chaoskey_class;
	35	static int chaoskey_rng_read(struct hwrng rng, void data,
	36	size_t max, bool wait);
	37
	38	#define usb_dbg(usb_if, format, arg...) \
	39	dev_dbg(&(usb_if)->dev, format, ## arg)
	40
	41	#define usb_err(usb_if, format, arg...) \
	42	dev_err(&(usb_if)->dev, format, ## arg)
	43
	44	/* Version Information */
	45	#define DRIVER_VERSION "v0.1"
	46	#define DRIVER_AUTHOR "Keith Packard, keithp@keithp.com"
	47	#define DRIVER_DESC "Altus Metrum ChaosKey driver"
	48	#define DRIVER_SHORT "chaoskey"
	49
	50	MODULE_VERSION(DRIVER_VERSION);
	51	MODULE_AUTHOR(DRIVER_AUTHOR);
	52	MODULE_DESCRIPTION(DRIVER_DESC);
	53	MODULE_LICENSE("GPL");
	54
	55	#define CHAOSKEY_VENDOR_ID 0x1d50 /* OpenMoko */
	56	#define CHAOSKEY_PRODUCT_ID 0x60c6 /* ChaosKey */
	57
d3ede2db BH	58	#define ALEA_VENDOR_ID 0x12d8 /* Araneus */
	59	#define ALEA_PRODUCT_ID 0x0001 /* Alea I */
	60
66e3e591 KP	61	#define CHAOSKEY_BUF_LEN 64 /* max size of USB full speed packet */
66e3e591 KP	62
e4a886e8 BH	63	#define NAK_TIMEOUT (HZ) /* normal stall/wait timeout */
e4a886e8 BH	64	#define ALEA_FIRST_TIMEOUT (HZ3) / first stall/wait timeout for Alea */
66e3e591 KP	65
	66	#ifdef CONFIG_USB_DYNAMIC_MINORS
	67	#define USB_CHAOSKEY_MINOR_BASE 0
	68	#else
	69
	70	/* IOWARRIOR_MINOR_BASE + 16, not official yet */
	71	#define USB_CHAOSKEY_MINOR_BASE 224
	72	#endif
	73
	74	static const struct usb_device_id chaoskey_table[] = {
	75	{ USB_DEVICE(CHAOSKEY_VENDOR_ID, CHAOSKEY_PRODUCT_ID) },
d3ede2db	76	{ USB_DEVICE(ALEA_VENDOR_ID, ALEA_PRODUCT_ID) },
66e3e591 KP	77	{ },
	78	};
	79	MODULE_DEVICE_TABLE(usb, chaoskey_table);
	80
0ca10122 ON	81	static void chaos_read_callback(struct urb *urb);
0ca10122 ON	82
66e3e591 KP	83	/* Driver-local specific stuff */
	84	struct chaoskey {
	85	struct usb_interface *interface;
	86	char in_ep;
	87	struct mutex lock;
	88	struct mutex rng_lock;
	89	int open; /* open count */
0ca10122 ON	90	bool present; /* device not disconnected */
0ca10122 ON	91	bool reading; /* ongoing IO */
e4a886e8	92	bool reads_started; /* track first read for Alea */
66e3e591 KP	93	int size; /* size of buf */
	94	int valid; /* bytes of buf read */
	95	int used; /* bytes of buf consumed */
	96	char name; / product + serial */
	97	struct hwrng hwrng; /* Embedded struct for hwrng */
	98	int hwrng_registered; /* registered with hwrng API */
	99	wait_queue_head_t wait_q; /* for timeouts */
0ca10122	100	struct urb urb; / for performing IO */
66e3e591 KP	101	char *buf;
	102	};
	103
	104	static void chaoskey_free(struct chaoskey *dev)
	105	{
0a15e24c ON	106	if (dev) {
0a15e24c ON	107	usb_dbg(dev->interface, "free");
0ca10122	108	usb_free_urb(dev->urb);
0a15e24c ON	109	kfree(dev->name);
	110	kfree(dev->buf);
	111	kfree(dev);
	112	}
66e3e591 KP	113	}
	114
	115	static int chaoskey_probe(struct usb_interface *interface,
	116	const struct usb_device_id *id)
	117	{
	118	struct usb_device *udev = interface_to_usbdev(interface);
	119	struct usb_host_interface *altsetting = interface->cur_altsetting;
a8bbb0f8 JH	120	struct usb_endpoint_descriptor *epd;
a8bbb0f8 JH	121	int in_ep;
66e3e591	122	struct chaoskey *dev;
0a15e24c	123	int result = -ENOMEM;
66e3e591	124	int size;
a8bbb0f8	125	int res;
66e3e591 KP	126
	127	usb_dbg(interface, "probe %s-%s", udev->product, udev->serial);
	128
	129	/* Find the first bulk IN endpoint and its packet size */
a8bbb0f8 JH	130	res = usb_find_bulk_in_endpoint(altsetting, &epd);
	131	if (res) {
	132	usb_dbg(interface, "no IN endpoint found");
	133	return res;
66e3e591 KP	134	}
66e3e591 KP	135
a8bbb0f8 JH	136	in_ep = usb_endpoint_num(epd);
	137	size = usb_endpoint_maxp(epd);
	138
66e3e591	139	/* Validate endpoint and size */
66e3e591 KP	140	if (size <= 0) {
	141	usb_dbg(interface, "invalid size (%d)", size);
	142	return -ENODEV;
	143	}
	144
	145	if (size > CHAOSKEY_BUF_LEN) {
	146	usb_dbg(interface, "size reduced from %d to %d\n",
	147	size, CHAOSKEY_BUF_LEN);
	148	size = CHAOSKEY_BUF_LEN;
	149	}
	150
	151	/* Looks good, allocate and initialize */
	152
	153	dev = kzalloc(sizeof(struct chaoskey), GFP_KERNEL);
	154
	155	if (dev == NULL)
0a15e24c	156	goto out;
66e3e591 KP	157
	158	dev->buf = kmalloc(size, GFP_KERNEL);
	159
0a15e24c ON	160	if (dev->buf == NULL)
0a15e24c ON	161	goto out;
66e3e591	162
0ca10122 ON	163	dev->urb = usb_alloc_urb(0, GFP_KERNEL);
	164
	165	if (!dev->urb)
	166	goto out;
	167
	168	usb_fill_bulk_urb(dev->urb,
	169	udev,
	170	usb_rcvbulkpipe(udev, in_ep),
	171	dev->buf,
	172	size,
	173	chaos_read_callback,
	174	dev);
	175
66e3e591 KP	176	/* Construct a name using the product and serial values. Each
	177	* device needs a unique name for the hwrng code
	178	*/
	179
	180	if (udev->product && udev->serial) {
	181	dev->name = kmalloc(strlen(udev->product) + 1 +
	182	strlen(udev->serial) + 1, GFP_KERNEL);
0a15e24c ON	183	if (dev->name == NULL)
0a15e24c ON	184	goto out;
66e3e591 KP	185
	186	strcpy(dev->name, udev->product);
	187	strcat(dev->name, "-");
	188	strcat(dev->name, udev->serial);
	189	}
	190
	191	dev->interface = interface;
	192
	193	dev->in_ep = in_ep;
	194
63afd5cc	195	if (le16_to_cpu(udev->descriptor.idVendor) != ALEA_VENDOR_ID)
e4a886e8 BH	196	dev->reads_started = 1;
e4a886e8 BH	197
66e3e591 KP	198	dev->size = size;
	199	dev->present = 1;
	200
	201	init_waitqueue_head(&dev->wait_q);
	202
	203	mutex_init(&dev->lock);
	204	mutex_init(&dev->rng_lock);
	205
	206	usb_set_intfdata(interface, dev);
	207
	208	result = usb_register_dev(interface, &chaoskey_class);
	209	if (result) {
	210	usb_err(interface, "Unable to allocate minor number.");
0a15e24c	211	goto out;
66e3e591 KP	212	}
	213
	214	dev->hwrng.name = dev->name ? dev->name : chaoskey_driver.name;
	215	dev->hwrng.read = chaoskey_rng_read;
6fbbcf38	216	dev->hwrng.quality = 1024;
66e3e591 KP	217
	218	dev->hwrng_registered = (hwrng_register(&dev->hwrng) == 0);
	219	if (!dev->hwrng_registered)
	220	usb_err(interface, "Unable to register with hwrng");
	221
	222	usb_enable_autosuspend(udev);
	223
	224	usb_dbg(interface, "chaoskey probe success, size %d", dev->size);
	225	return 0;
0a15e24c ON	226
	227	out:
	228	usb_set_intfdata(interface, NULL);
	229	chaoskey_free(dev);
	230	return result;
66e3e591 KP	231	}
	232
	233	static void chaoskey_disconnect(struct usb_interface *interface)
	234	{
	235	struct chaoskey *dev;
	236
	237	usb_dbg(interface, "disconnect");
	238	dev = usb_get_intfdata(interface);
	239	if (!dev) {
	240	usb_dbg(interface, "disconnect failed - no dev");
	241	return;
	242	}
	243
	244	if (dev->hwrng_registered)
	245	hwrng_unregister(&dev->hwrng);
	246
	247	usb_deregister_dev(interface, &chaoskey_class);
	248
	249	usb_set_intfdata(interface, NULL);
	250	mutex_lock(&dev->lock);
	251
	252	dev->present = 0;
0ca10122	253	usb_poison_urb(dev->urb);
66e3e591 KP	254
	255	if (!dev->open) {
	256	mutex_unlock(&dev->lock);
	257	chaoskey_free(dev);
	258	} else
	259	mutex_unlock(&dev->lock);
	260
	261	usb_dbg(interface, "disconnect done");
	262	}
	263
	264	static int chaoskey_open(struct inode inode, struct file file)
	265	{
	266	struct chaoskey *dev;
	267	struct usb_interface *interface;
	268
	269	/* get the interface from minor number and driver information */
	270	interface = usb_find_interface(&chaoskey_driver, iminor(inode));
	271	if (!interface)
	272	return -ENODEV;
	273
	274	usb_dbg(interface, "open");
	275
	276	dev = usb_get_intfdata(interface);
	277	if (!dev) {
	278	usb_dbg(interface, "open (dev)");
	279	return -ENODEV;
	280	}
	281
	282	file->private_data = dev;
	283	mutex_lock(&dev->lock);
	284	++dev->open;
	285	mutex_unlock(&dev->lock);
	286
	287	usb_dbg(interface, "open success");
	288	return 0;
	289	}
	290
	291	static int chaoskey_release(struct inode inode, struct file file)
	292	{
	293	struct chaoskey *dev = file->private_data;
	294	struct usb_interface *interface;
	295
	296	if (dev == NULL)
	297	return -ENODEV;
	298
	299	interface = dev->interface;
	300
	301	usb_dbg(interface, "release");
	302
	303	mutex_lock(&dev->lock);
	304
	305	usb_dbg(interface, "open count at release is %d", dev->open);
	306
	307	if (dev->open <= 0) {
	308	usb_dbg(interface, "invalid open count (%d)", dev->open);
	309	mutex_unlock(&dev->lock);
	310	return -ENODEV;
	311	}
	312
	313	--dev->open;
	314
	315	if (!dev->present) {
	316	if (dev->open == 0) {
	317	mutex_unlock(&dev->lock);
318	chaoskey_free(dev);
319	} else
320	mutex_unlock(&dev->lock);
321	} else
322	mutex_unlock(&dev->lock);
323
324	usb_dbg(interface, "release success");
325	return 0;
326	}
327
0ca10122 ON	328	static void chaos_read_callback(struct urb *urb)
	329	{
	330	struct chaoskey *dev = urb->context;
	331	int status = urb->status;
	332
	333	usb_dbg(dev->interface, "callback status (%d)", status);
	334
	335	if (status == 0)
	336	dev->valid = urb->actual_length;
	337	else
	338	dev->valid = 0;
	339
	340	dev->used = 0;
	341
	342	/* must be seen first before validity is announced */
	343	smp_wmb();
	344
	345	dev->reading = false;
	346	wake_up(&dev->wait_q);
	347	}
	348
66e3e591 KP	349	/* Fill the buffer. Called with dev->lock held
	350	*/
	351	static int _chaoskey_fill(struct chaoskey *dev)
	352	{
	353	DEFINE_WAIT(wait);
	354	int result;
e4a886e8	355	bool started;
66e3e591 KP	356
	357	usb_dbg(dev->interface, "fill");
	358
	359	/* Return immediately if someone called before the buffer was
	360	* empty */
	361	if (dev->valid != dev->used) {
	362	usb_dbg(dev->interface, "not empty yet (valid %d used %d)",
	363	dev->valid, dev->used);
	364	return 0;
	365	}
	366
	367	/* Bail if the device has been removed */
	368	if (!dev->present) {
	369	usb_dbg(dev->interface, "device not present");
	370	return -ENODEV;
	371	}
	372
	373	/* Make sure the device is awake */
	374	result = usb_autopm_get_interface(dev->interface);
	375	if (result) {
	376	usb_dbg(dev->interface, "wakeup failed (result %d)", result);
	377	return result;
	378	}
	379
0ca10122 ON	380	dev->reading = true;
	381	result = usb_submit_urb(dev->urb, GFP_KERNEL);
	382	if (result < 0) {
	383	result = usb_translate_errors(result);
	384	dev->reading = false;
	385	goto out;
	386	}
	387
e4a886e8 BH	388	/* The first read on the Alea takes a little under 2 seconds.
	389	* Reads after the first read take only a few microseconds
	390	* though. Presumably the entropy-generating circuit needs
	391	* time to ramp up. So, we wait longer on the first read.
	392	*/
	393	started = dev->reads_started;
	394	dev->reads_started = true;
0ca10122 ON	395	result = wait_event_interruptible_timeout(
	396	dev->wait_q,
	397	!dev->reading,
e4a886e8	398	(started ? NAK_TIMEOUT : ALEA_FIRST_TIMEOUT) );
66e3e591	399
0ca10122 ON	400	if (result < 0)
	401	goto out;
	402
	403	if (result == 0)
	404	result = -ETIMEDOUT;
	405	else
	406	result = dev->valid;
	407	out:
66e3e591 KP	408	/* Let the device go back to sleep eventually */
	409	usb_autopm_put_interface(dev->interface);
	410
0ca10122	411	usb_dbg(dev->interface, "read %d bytes", dev->valid);
66e3e591 KP	412
	413	return result;
	414	}
	415
	416	static ssize_t chaoskey_read(struct file *file,
	417	char __user *buffer,
	418	size_t count,
	419	loff_t *ppos)
	420	{
	421	struct chaoskey *dev;
	422	ssize_t read_count = 0;
	423	int this_time;
	424	int result = 0;
	425	unsigned long remain;
	426
	427	dev = file->private_data;
	428
	429	if (dev == NULL \|\| !dev->present)
	430	return -ENODEV;
	431
	432	usb_dbg(dev->interface, "read %zu", count);
	433
	434	while (count > 0) {
	435
	436	/* Grab the rng_lock briefly to ensure that the hwrng interface
	437	* gets priority over other user access
	438	*/
	439	result = mutex_lock_interruptible(&dev->rng_lock);
	440	if (result)
	441	goto bail;
	442	mutex_unlock(&dev->rng_lock);
	443
	444	result = mutex_lock_interruptible(&dev->lock);
	445	if (result)
	446	goto bail;
	447	if (dev->valid == dev->used) {
	448	result = _chaoskey_fill(dev);
0ca10122	449	if (result < 0) {
66e3e591 KP	450	mutex_unlock(&dev->lock);
	451	goto bail;
	452	}
	453	}
	454
	455	this_time = dev->valid - dev->used;
	456	if (this_time > count)
	457	this_time = count;
	458
	459	remain = copy_to_user(buffer, dev->buf + dev->used, this_time);
	460	if (remain) {
	461	result = -EFAULT;
	462
	463	/* Consume the bytes that were copied so we don't leak
	464	* data to user space
	465	*/
	466	dev->used += this_time - remain;
	467	mutex_unlock(&dev->lock);
	468	goto bail;
	469	}
	470
	471	count -= this_time;
	472	read_count += this_time;
	473	buffer += this_time;
	474	dev->used += this_time;
	475	mutex_unlock(&dev->lock);
	476	}
	477	bail:
	478	if (read_count) {
	479	usb_dbg(dev->interface, "read %zu bytes", read_count);
	480	return read_count;
	481	}
	482	usb_dbg(dev->interface, "empty read, result %d", result);
0ca10122 ON	483	if (result == -ETIMEDOUT)
0ca10122 ON	484	result = -EAGAIN;
66e3e591 KP	485	return result;
	486	}
	487
	488	static int chaoskey_rng_read(struct hwrng rng, void data,
	489	size_t max, bool wait)
	490	{
	491	struct chaoskey *dev = container_of(rng, struct chaoskey, hwrng);
	492	int this_time;
	493
	494	usb_dbg(dev->interface, "rng_read max %zu wait %d", max, wait);
	495
	496	if (!dev->present) {
	497	usb_dbg(dev->interface, "device not present");
	498	return 0;
	499	}
	500
	501	/* Hold the rng_lock until we acquire the device lock so that
	502	* this operation gets priority over other user access to the
	503	* device
	504	*/
	505	mutex_lock(&dev->rng_lock);
	506
	507	mutex_lock(&dev->lock);
	508
	509	mutex_unlock(&dev->rng_lock);
	510
	511	/* Try to fill the buffer if empty. It doesn't actually matter
	512	* if _chaoskey_fill works; we'll just return zero bytes as
	513	* the buffer will still be empty
	514	*/
	515	if (dev->valid == dev->used)
	516	(void) _chaoskey_fill(dev);
	517
	518	this_time = dev->valid - dev->used;
	519	if (this_time > max)
	520	this_time = max;
	521
1d5c47f5	522	memcpy(data, dev->buf + dev->used, this_time);
66e3e591 KP	523
	524	dev->used += this_time;
	525
	526	mutex_unlock(&dev->lock);
	527
	528	usb_dbg(dev->interface, "rng_read this_time %d\n", this_time);
	529	return this_time;
	530	}
	531
	532	#ifdef CONFIG_PM
	533	static int chaoskey_suspend(struct usb_interface *interface,
	534	pm_message_t message)
	535	{
	536	usb_dbg(interface, "suspend");
	537	return 0;
	538	}
	539
	540	static int chaoskey_resume(struct usb_interface *interface)
	541	{
	542	usb_dbg(interface, "resume");
	543	return 0;
	544	}
	545	#else
	546	#define chaoskey_suspend NULL
	547	#define chaoskey_resume NULL
	548	#endif
	549
	550	/* file operation pointers */
	551	static const struct file_operations chaoskey_fops = {
	552	.owner = THIS_MODULE,
	553	.read = chaoskey_read,
	554	.open = chaoskey_open,
	555	.release = chaoskey_release,
	556	.llseek = default_llseek,
	557	};
	558
	559	/* class driver information */
	560	static struct usb_class_driver chaoskey_class = {
	561	.name = "chaoskey%d",
	562	.fops = &chaoskey_fops,
	563	.minor_base = USB_CHAOSKEY_MINOR_BASE,
	564	};
	565
	566	/* usb specific object needed to register this driver with the usb subsystem */
	567	static struct usb_driver chaoskey_driver = {
	568	.name = DRIVER_SHORT,
	569	.probe = chaoskey_probe,
	570	.disconnect = chaoskey_disconnect,
	571	.suspend = chaoskey_suspend,
	572	.resume = chaoskey_resume,
	573	.reset_resume = chaoskey_resume,
	574	.id_table = chaoskey_table,
	575	.supports_autosuspend = 1,
	576	};
	577
	578	module_usb_driver(chaoskey_driver);
	579