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

// SPDX-License-Identifier: GPL-2.0
/*
 * 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_AUTHOR	"Keith Packard, keithp@keithp.com"
#define DRIVER_DESC	"Altus Metrum ChaosKey driver"
#define DRIVER_SHORT	"chaoskey"

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
5fd54ace	1	// SPDX-License-Identifier: GPL-2.0
66e3e591 KP	2	/*
	3	* chaoskey - driver for ChaosKey device from Altus Metrum.
	4	*
	5	* This device provides true random numbers using a noise source based
	6	* on a reverse-biased p-n junction in avalanche breakdown. More
	7	* details can be found at http://chaoskey.org
	8	*
	9	* The driver connects to the kernel hardware RNG interface to provide
	10	* entropy for /dev/random and other kernel activities. It also offers
	11	* a separate /dev/ entry to allow for direct access to the random
	12	* bit stream.
	13	*
	14	* Copyright © 2015 Keith Packard <keithp@keithp.com>
	15	*
	16	* This program is free software; you can redistribute it and/or modify
	17	* it under the terms of the GNU General Public License as published by
	18	* the Free Software Foundation; version 2 of the License.
	19	*
	20	* This program is distributed in the hope that it will be useful, but
	21	* WITHOUT ANY WARRANTY; without even the implied warranty of
	22	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	23	* General Public License for more details.
	24	*/
	25
	26	#include <linux/module.h>
	27	#include <linux/slab.h>
	28	#include <linux/usb.h>
	29	#include <linux/wait.h>
	30	#include <linux/hw_random.h>
8b86ed07 KP	31	#include <linux/mutex.h>
8b86ed07 KP	32	#include <linux/uaccess.h>
66e3e591 KP	33
	34	static struct usb_driver chaoskey_driver;
	35	static struct usb_class_driver chaoskey_class;
	36	static int chaoskey_rng_read(struct hwrng rng, void data,
	37	size_t max, bool wait);
	38
	39	#define usb_dbg(usb_if, format, arg...) \
	40	dev_dbg(&(usb_if)->dev, format, ## arg)
	41
	42	#define usb_err(usb_if, format, arg...) \
	43	dev_err(&(usb_if)->dev, format, ## arg)
	44
	45	/* Version Information */
66e3e591 KP	46	#define DRIVER_AUTHOR "Keith Packard, keithp@keithp.com"
	47	#define DRIVER_DESC "Altus Metrum ChaosKey driver"
	48	#define DRIVER_SHORT "chaoskey"
	49
66e3e591 KP	50	MODULE_AUTHOR(DRIVER_AUTHOR);
	51	MODULE_DESCRIPTION(DRIVER_DESC);
	52	MODULE_LICENSE("GPL");
	53
	54	#define CHAOSKEY_VENDOR_ID 0x1d50 /* OpenMoko */
	55	#define CHAOSKEY_PRODUCT_ID 0x60c6 /* ChaosKey */
	56
d3ede2db BH	57	#define ALEA_VENDOR_ID 0x12d8 /* Araneus */
	58	#define ALEA_PRODUCT_ID 0x0001 /* Alea I */
	59
66e3e591 KP	60	#define CHAOSKEY_BUF_LEN 64 /* max size of USB full speed packet */
66e3e591 KP	61
e4a886e8 BH	62	#define NAK_TIMEOUT (HZ) /* normal stall/wait timeout */
e4a886e8 BH	63	#define ALEA_FIRST_TIMEOUT (HZ3) / first stall/wait timeout for Alea */
66e3e591 KP	64
	65	#ifdef CONFIG_USB_DYNAMIC_MINORS
	66	#define USB_CHAOSKEY_MINOR_BASE 0
	67	#else
	68
	69	/* IOWARRIOR_MINOR_BASE + 16, not official yet */
	70	#define USB_CHAOSKEY_MINOR_BASE 224
	71	#endif
	72
	73	static const struct usb_device_id chaoskey_table[] = {
	74	{ USB_DEVICE(CHAOSKEY_VENDOR_ID, CHAOSKEY_PRODUCT_ID) },
d3ede2db	75	{ USB_DEVICE(ALEA_VENDOR_ID, ALEA_PRODUCT_ID) },
66e3e591 KP	76	{ },
	77	};
	78	MODULE_DEVICE_TABLE(usb, chaoskey_table);
	79
0ca10122 ON	80	static void chaos_read_callback(struct urb *urb);
0ca10122 ON	81
66e3e591 KP	82	/* Driver-local specific stuff */
	83	struct chaoskey {
	84	struct usb_interface *interface;
	85	char in_ep;
	86	struct mutex lock;
	87	struct mutex rng_lock;
	88	int open; /* open count */
0ca10122 ON	89	bool present; /* device not disconnected */
0ca10122 ON	90	bool reading; /* ongoing IO */
e4a886e8	91	bool reads_started; /* track first read for Alea */
66e3e591 KP	92	int size; /* size of buf */
	93	int valid; /* bytes of buf read */
	94	int used; /* bytes of buf consumed */
	95	char name; / product + serial */
	96	struct hwrng hwrng; /* Embedded struct for hwrng */
	97	int hwrng_registered; /* registered with hwrng API */
	98	wait_queue_head_t wait_q; /* for timeouts */
0ca10122	99	struct urb urb; / for performing IO */
66e3e591 KP	100	char *buf;
	101	};
	102
	103	static void chaoskey_free(struct chaoskey *dev)
	104	{
0a15e24c ON	105	if (dev) {
0a15e24c ON	106	usb_dbg(dev->interface, "free");
0ca10122	107	usb_free_urb(dev->urb);
0a15e24c ON	108	kfree(dev->name);
	109	kfree(dev->buf);
	110	kfree(dev);
	111	}
66e3e591 KP	112	}
	113
	114	static int chaoskey_probe(struct usb_interface *interface,
	115	const struct usb_device_id *id)
	116	{
	117	struct usb_device *udev = interface_to_usbdev(interface);
	118	struct usb_host_interface *altsetting = interface->cur_altsetting;
a8bbb0f8 JH	119	struct usb_endpoint_descriptor *epd;
a8bbb0f8 JH	120	int in_ep;
66e3e591	121	struct chaoskey *dev;
0a15e24c	122	int result = -ENOMEM;
66e3e591	123	int size;
a8bbb0f8	124	int res;
66e3e591 KP	125
	126	usb_dbg(interface, "probe %s-%s", udev->product, udev->serial);
	127
	128	/* Find the first bulk IN endpoint and its packet size */
a8bbb0f8 JH	129	res = usb_find_bulk_in_endpoint(altsetting, &epd);
	130	if (res) {
	131	usb_dbg(interface, "no IN endpoint found");
	132	return res;
66e3e591 KP	133	}
66e3e591 KP	134
a8bbb0f8 JH	135	in_ep = usb_endpoint_num(epd);
	136	size = usb_endpoint_maxp(epd);
	137
66e3e591	138	/* Validate endpoint and size */
66e3e591 KP	139	if (size <= 0) {
	140	usb_dbg(interface, "invalid size (%d)", size);
	141	return -ENODEV;
	142	}
	143
	144	if (size > CHAOSKEY_BUF_LEN) {
	145	usb_dbg(interface, "size reduced from %d to %d\n",
	146	size, CHAOSKEY_BUF_LEN);
	147	size = CHAOSKEY_BUF_LEN;
	148	}
	149
	150	/* Looks good, allocate and initialize */
	151
	152	dev = kzalloc(sizeof(struct chaoskey), GFP_KERNEL);
	153
	154	if (dev == NULL)
0a15e24c	155	goto out;
66e3e591 KP	156
	157	dev->buf = kmalloc(size, GFP_KERNEL);
	158
0a15e24c ON	159	if (dev->buf == NULL)
0a15e24c ON	160	goto out;
66e3e591	161
0ca10122 ON	162	dev->urb = usb_alloc_urb(0, GFP_KERNEL);
	163
	164	if (!dev->urb)
	165	goto out;
	166
	167	usb_fill_bulk_urb(dev->urb,
	168	udev,
	169	usb_rcvbulkpipe(udev, in_ep),
	170	dev->buf,
	171	size,
	172	chaos_read_callback,
	173	dev);
	174
66e3e591 KP	175	/* Construct a name using the product and serial values. Each
	176	* device needs a unique name for the hwrng code
	177	*/
	178
	179	if (udev->product && udev->serial) {
	180	dev->name = kmalloc(strlen(udev->product) + 1 +
	181	strlen(udev->serial) + 1, GFP_KERNEL);
0a15e24c ON	182	if (dev->name == NULL)
0a15e24c ON	183	goto out;
66e3e591 KP	184
	185	strcpy(dev->name, udev->product);
	186	strcat(dev->name, "-");
	187	strcat(dev->name, udev->serial);
	188	}
	189
	190	dev->interface = interface;
	191
	192	dev->in_ep = in_ep;
	193
63afd5cc	194	if (le16_to_cpu(udev->descriptor.idVendor) != ALEA_VENDOR_ID)
e4a886e8 BH	195	dev->reads_started = 1;
e4a886e8 BH	196
66e3e591 KP	197	dev->size = size;
	198	dev->present = 1;
	199
	200	init_waitqueue_head(&dev->wait_q);
	201
	202	mutex_init(&dev->lock);
	203	mutex_init(&dev->rng_lock);
	204
	205	usb_set_intfdata(interface, dev);
	206
	207	result = usb_register_dev(interface, &chaoskey_class);
	208	if (result) {
	209	usb_err(interface, "Unable to allocate minor number.");
0a15e24c	210	goto out;
66e3e591 KP	211	}
	212
	213	dev->hwrng.name = dev->name ? dev->name : chaoskey_driver.name;
	214	dev->hwrng.read = chaoskey_rng_read;
6fbbcf38	215	dev->hwrng.quality = 1024;
66e3e591 KP	216
	217	dev->hwrng_registered = (hwrng_register(&dev->hwrng) == 0);
	218	if (!dev->hwrng_registered)
	219	usb_err(interface, "Unable to register with hwrng");
	220
	221	usb_enable_autosuspend(udev);
	222
	223	usb_dbg(interface, "chaoskey probe success, size %d", dev->size);
	224	return 0;
0a15e24c ON	225
	226	out:
	227	usb_set_intfdata(interface, NULL);
	228	chaoskey_free(dev);
	229	return result;
66e3e591 KP	230	}
	231
	232	static void chaoskey_disconnect(struct usb_interface *interface)
	233	{
	234	struct chaoskey *dev;
	235
	236	usb_dbg(interface, "disconnect");
	237	dev = usb_get_intfdata(interface);
	238	if (!dev) {
	239	usb_dbg(interface, "disconnect failed - no dev");
	240	return;
	241	}
	242
	243	if (dev->hwrng_registered)
	244	hwrng_unregister(&dev->hwrng);
	245
	246	usb_deregister_dev(interface, &chaoskey_class);
	247
	248	usb_set_intfdata(interface, NULL);
	249	mutex_lock(&dev->lock);
	250
	251	dev->present = 0;
0ca10122	252	usb_poison_urb(dev->urb);
66e3e591 KP	253
	254	if (!dev->open) {
	255	mutex_unlock(&dev->lock);
	256	chaoskey_free(dev);
	257	} else
	258	mutex_unlock(&dev->lock);
	259
	260	usb_dbg(interface, "disconnect done");
	261	}
	262
	263	static int chaoskey_open(struct inode inode, struct file file)
	264	{
	265	struct chaoskey *dev;
	266	struct usb_interface *interface;
	267
	268	/* get the interface from minor number and driver information */
	269	interface = usb_find_interface(&chaoskey_driver, iminor(inode));
	270	if (!interface)
	271	return -ENODEV;
	272
	273	usb_dbg(interface, "open");
	274
	275	dev = usb_get_intfdata(interface);
	276	if (!dev) {
	277	usb_dbg(interface, "open (dev)");
	278	return -ENODEV;
	279	}
	280
	281	file->private_data = dev;
	282	mutex_lock(&dev->lock);
	283	++dev->open;
	284	mutex_unlock(&dev->lock);
	285
	286	usb_dbg(interface, "open success");
	287	return 0;
	288	}
	289
	290	static int chaoskey_release(struct inode inode, struct file file)
	291	{
	292	struct chaoskey *dev = file->private_data;
	293	struct usb_interface *interface;
	294
	295	if (dev == NULL)
	296	return -ENODEV;
	297
	298	interface = dev->interface;
	299
	300	usb_dbg(interface, "release");
	301
	302	mutex_lock(&dev->lock);
	303
	304	usb_dbg(interface, "open count at release is %d", dev->open);
	305
	306	if (dev->open <= 0) {
	307	usb_dbg(interface, "invalid open count (%d)", dev->open);
	308	mutex_unlock(&dev->lock);
	309	return -ENODEV;
	310	}
	311
	312	--dev->open;
	313
	314	if (!dev->present) {
	315	if (dev->open == 0) {
	316	mutex_unlock(&dev->lock);
317	chaoskey_free(dev);
318	} else
319	mutex_unlock(&dev->lock);
320	} else
321	mutex_unlock(&dev->lock);
322
323	usb_dbg(interface, "release success");
324	return 0;
325	}
326
0ca10122 ON	327	static void chaos_read_callback(struct urb *urb)
	328	{
	329	struct chaoskey *dev = urb->context;
	330	int status = urb->status;
	331
	332	usb_dbg(dev->interface, "callback status (%d)", status);
	333
	334	if (status == 0)
	335	dev->valid = urb->actual_length;
	336	else
	337	dev->valid = 0;
	338
	339	dev->used = 0;
	340
	341	/* must be seen first before validity is announced */
	342	smp_wmb();
	343
	344	dev->reading = false;
	345	wake_up(&dev->wait_q);
	346	}
	347
66e3e591 KP	348	/* Fill the buffer. Called with dev->lock held
	349	*/
	350	static int _chaoskey_fill(struct chaoskey *dev)
	351	{
	352	DEFINE_WAIT(wait);
	353	int result;
e4a886e8	354	bool started;
66e3e591 KP	355
	356	usb_dbg(dev->interface, "fill");
	357
	358	/* Return immediately if someone called before the buffer was
	359	* empty */
	360	if (dev->valid != dev->used) {
	361	usb_dbg(dev->interface, "not empty yet (valid %d used %d)",
	362	dev->valid, dev->used);
	363	return 0;
	364	}
	365
	366	/* Bail if the device has been removed */
	367	if (!dev->present) {
	368	usb_dbg(dev->interface, "device not present");
	369	return -ENODEV;
	370	}
	371
	372	/* Make sure the device is awake */
	373	result = usb_autopm_get_interface(dev->interface);
	374	if (result) {
	375	usb_dbg(dev->interface, "wakeup failed (result %d)", result);
	376	return result;
	377	}
	378
0ca10122 ON	379	dev->reading = true;
	380	result = usb_submit_urb(dev->urb, GFP_KERNEL);
	381	if (result < 0) {
	382	result = usb_translate_errors(result);
	383	dev->reading = false;
	384	goto out;
	385	}
	386
e4a886e8 BH	387	/* The first read on the Alea takes a little under 2 seconds.
	388	* Reads after the first read take only a few microseconds
	389	* though. Presumably the entropy-generating circuit needs
	390	* time to ramp up. So, we wait longer on the first read.
	391	*/
	392	started = dev->reads_started;
	393	dev->reads_started = true;
0ca10122 ON	394	result = wait_event_interruptible_timeout(
	395	dev->wait_q,
	396	!dev->reading,
e4a886e8	397	(started ? NAK_TIMEOUT : ALEA_FIRST_TIMEOUT) );
66e3e591	398
0ca10122 ON	399	if (result < 0)
	400	goto out;
	401
	402	if (result == 0)
	403	result = -ETIMEDOUT;
	404	else
	405	result = dev->valid;
	406	out:
66e3e591 KP	407	/* Let the device go back to sleep eventually */
	408	usb_autopm_put_interface(dev->interface);
	409
0ca10122	410	usb_dbg(dev->interface, "read %d bytes", dev->valid);
66e3e591 KP	411
	412	return result;
	413	}
	414
	415	static ssize_t chaoskey_read(struct file *file,
	416	char __user *buffer,
	417	size_t count,
	418	loff_t *ppos)
	419	{
	420	struct chaoskey *dev;
	421	ssize_t read_count = 0;
	422	int this_time;
	423	int result = 0;
	424	unsigned long remain;
	425
	426	dev = file->private_data;
	427
	428	if (dev == NULL \|\| !dev->present)
	429	return -ENODEV;
	430
	431	usb_dbg(dev->interface, "read %zu", count);
	432
	433	while (count > 0) {
	434
	435	/* Grab the rng_lock briefly to ensure that the hwrng interface
	436	* gets priority over other user access
	437	*/
	438	result = mutex_lock_interruptible(&dev->rng_lock);
	439	if (result)
	440	goto bail;
	441	mutex_unlock(&dev->rng_lock);
	442
	443	result = mutex_lock_interruptible(&dev->lock);
	444	if (result)
	445	goto bail;
	446	if (dev->valid == dev->used) {
	447	result = _chaoskey_fill(dev);
0ca10122	448	if (result < 0) {
66e3e591 KP	449	mutex_unlock(&dev->lock);
	450	goto bail;
	451	}
	452	}
	453
	454	this_time = dev->valid - dev->used;
	455	if (this_time > count)
	456	this_time = count;
	457
	458	remain = copy_to_user(buffer, dev->buf + dev->used, this_time);
	459	if (remain) {
	460	result = -EFAULT;
	461
	462	/* Consume the bytes that were copied so we don't leak
	463	* data to user space
	464	*/
	465	dev->used += this_time - remain;
	466	mutex_unlock(&dev->lock);
	467	goto bail;
	468	}
	469
	470	count -= this_time;
	471	read_count += this_time;
	472	buffer += this_time;
	473	dev->used += this_time;
	474	mutex_unlock(&dev->lock);
	475	}
	476	bail:
	477	if (read_count) {
	478	usb_dbg(dev->interface, "read %zu bytes", read_count);
	479	return read_count;
	480	}
	481	usb_dbg(dev->interface, "empty read, result %d", result);
0ca10122 ON	482	if (result == -ETIMEDOUT)
0ca10122 ON	483	result = -EAGAIN;
66e3e591 KP	484	return result;
	485	}
	486
	487	static int chaoskey_rng_read(struct hwrng rng, void data,
	488	size_t max, bool wait)
	489	{
	490	struct chaoskey *dev = container_of(rng, struct chaoskey, hwrng);
	491	int this_time;
	492
	493	usb_dbg(dev->interface, "rng_read max %zu wait %d", max, wait);
	494
	495	if (!dev->present) {
	496	usb_dbg(dev->interface, "device not present");
	497	return 0;
	498	}
	499
	500	/* Hold the rng_lock until we acquire the device lock so that
	501	* this operation gets priority over other user access to the
	502	* device
	503	*/
	504	mutex_lock(&dev->rng_lock);
	505
	506	mutex_lock(&dev->lock);
	507
	508	mutex_unlock(&dev->rng_lock);
	509
	510	/* Try to fill the buffer if empty. It doesn't actually matter
	511	* if _chaoskey_fill works; we'll just return zero bytes as
	512	* the buffer will still be empty
	513	*/
	514	if (dev->valid == dev->used)
	515	(void) _chaoskey_fill(dev);
	516
	517	this_time = dev->valid - dev->used;
	518	if (this_time > max)
	519	this_time = max;
	520
1d5c47f5	521	memcpy(data, dev->buf + dev->used, this_time);
66e3e591 KP	522
	523	dev->used += this_time;
	524
	525	mutex_unlock(&dev->lock);
	526
	527	usb_dbg(dev->interface, "rng_read this_time %d\n", this_time);
	528	return this_time;
	529	}
	530
	531	#ifdef CONFIG_PM
	532	static int chaoskey_suspend(struct usb_interface *interface,
	533	pm_message_t message)
	534	{
	535	usb_dbg(interface, "suspend");
	536	return 0;
	537	}
	538
	539	static int chaoskey_resume(struct usb_interface *interface)
	540	{
	541	usb_dbg(interface, "resume");
	542	return 0;
	543	}
	544	#else
	545	#define chaoskey_suspend NULL
	546	#define chaoskey_resume NULL
	547	#endif
	548
	549	/* file operation pointers */
	550	static const struct file_operations chaoskey_fops = {
	551	.owner = THIS_MODULE,
	552	.read = chaoskey_read,
	553	.open = chaoskey_open,
	554	.release = chaoskey_release,
	555	.llseek = default_llseek,
	556	};
	557
	558	/* class driver information */
	559	static struct usb_class_driver chaoskey_class = {
	560	.name = "chaoskey%d",
	561	.fops = &chaoskey_fops,
	562	.minor_base = USB_CHAOSKEY_MINOR_BASE,
	563	};
	564
	565	/* usb specific object needed to register this driver with the usb subsystem */
	566	static struct usb_driver chaoskey_driver = {
	567	.name = DRIVER_SHORT,
	568	.probe = chaoskey_probe,
	569	.disconnect = chaoskey_disconnect,
	570	.suspend = chaoskey_suspend,
	571	.resume = chaoskey_resume,
	572	.reset_resume = chaoskey_resume,
	573	.id_table = chaoskey_table,
	574	.supports_autosuspend = 1,
	575	};
	576
	577	module_usb_driver(chaoskey_driver);
	578