[linux-2.6-block.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;
	int i;
	int in_ep = -1;
	struct chaoskey *dev;
	int result = -ENOMEM;
	int size;

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

	/* Find the first bulk IN endpoint and its packet size */
	for (i = 0; i < altsetting->desc.bNumEndpoints; i++) {
		if (usb_endpoint_is_bulk_in(&altsetting->endpoint[i].desc)) {
			in_ep = usb_endpoint_num(&altsetting->endpoint[i].desc);
			size = usb_endpoint_maxp(&altsetting->endpoint[i].desc);
			break;
		}
	}

	/* Validate endpoint and size */
	if (in_ep == -1) {
		usb_dbg(interface, "no IN endpoint found");
		return -ENODEV;
	}
	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 (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;
	120	int i;
	121	int in_ep = -1;
	122	struct chaoskey *dev;
0a15e24c	123	int result = -ENOMEM;
66e3e591 KP	124	int size;
	125
	126	usb_dbg(interface, "probe %s-%s", udev->product, udev->serial);
	127
	128	/* Find the first bulk IN endpoint and its packet size */
	129	for (i = 0; i < altsetting->desc.bNumEndpoints; i++) {
	130	if (usb_endpoint_is_bulk_in(&altsetting->endpoint[i].desc)) {
8b86ed07 KP	131	in_ep = usb_endpoint_num(&altsetting->endpoint[i].desc);
8b86ed07 KP	132	size = usb_endpoint_maxp(&altsetting->endpoint[i].desc);
66e3e591 KP	133	break;
	134	}
	135	}
	136
	137	/* Validate endpoint and size */
	138	if (in_ep == -1) {
	139	usb_dbg(interface, "no IN endpoint found");
	140	return -ENODEV;
	141	}
	142	if (size <= 0) {
	143	usb_dbg(interface, "invalid size (%d)", size);
	144	return -ENODEV;
	145	}
	146
	147	if (size > CHAOSKEY_BUF_LEN) {
	148	usb_dbg(interface, "size reduced from %d to %d\n",
	149	size, CHAOSKEY_BUF_LEN);
	150	size = CHAOSKEY_BUF_LEN;
	151	}
	152
	153	/* Looks good, allocate and initialize */
	154
	155	dev = kzalloc(sizeof(struct chaoskey), GFP_KERNEL);
	156
	157	if (dev == NULL)
0a15e24c	158	goto out;
66e3e591 KP	159
	160	dev->buf = kmalloc(size, GFP_KERNEL);
	161
0a15e24c ON	162	if (dev->buf == NULL)
0a15e24c ON	163	goto out;
66e3e591	164
0ca10122 ON	165	dev->urb = usb_alloc_urb(0, GFP_KERNEL);
	166
	167	if (!dev->urb)
	168	goto out;
	169
	170	usb_fill_bulk_urb(dev->urb,
	171	udev,
	172	usb_rcvbulkpipe(udev, in_ep),
	173	dev->buf,
	174	size,
	175	chaos_read_callback,
	176	dev);
	177
66e3e591 KP	178	/* Construct a name using the product and serial values. Each
	179	* device needs a unique name for the hwrng code
	180	*/
	181
	182	if (udev->product && udev->serial) {
	183	dev->name = kmalloc(strlen(udev->product) + 1 +
	184	strlen(udev->serial) + 1, GFP_KERNEL);
0a15e24c ON	185	if (dev->name == NULL)
0a15e24c ON	186	goto out;
66e3e591 KP	187
	188	strcpy(dev->name, udev->product);
	189	strcat(dev->name, "-");
	190	strcat(dev->name, udev->serial);
	191	}
	192
	193	dev->interface = interface;
	194
	195	dev->in_ep = in_ep;
	196
e4a886e8 BH	197	if (udev->descriptor.idVendor != ALEA_VENDOR_ID)
	198	dev->reads_started = 1;
	199
66e3e591 KP	200	dev->size = size;
	201	dev->present = 1;
	202
	203	init_waitqueue_head(&dev->wait_q);
	204
	205	mutex_init(&dev->lock);
	206	mutex_init(&dev->rng_lock);
	207
	208	usb_set_intfdata(interface, dev);
	209
	210	result = usb_register_dev(interface, &chaoskey_class);
	211	if (result) {
	212	usb_err(interface, "Unable to allocate minor number.");
0a15e24c	213	goto out;
66e3e591 KP	214	}
	215
	216	dev->hwrng.name = dev->name ? dev->name : chaoskey_driver.name;
	217	dev->hwrng.read = chaoskey_rng_read;
6fbbcf38	218	dev->hwrng.quality = 1024;
66e3e591 KP	219
	220	dev->hwrng_registered = (hwrng_register(&dev->hwrng) == 0);
	221	if (!dev->hwrng_registered)
	222	usb_err(interface, "Unable to register with hwrng");
	223
	224	usb_enable_autosuspend(udev);
	225
	226	usb_dbg(interface, "chaoskey probe success, size %d", dev->size);
	227	return 0;
0a15e24c ON	228
	229	out:
	230	usb_set_intfdata(interface, NULL);
	231	chaoskey_free(dev);
	232	return result;
66e3e591 KP	233	}
	234
	235	static void chaoskey_disconnect(struct usb_interface *interface)
	236	{
	237	struct chaoskey *dev;
	238
	239	usb_dbg(interface, "disconnect");
	240	dev = usb_get_intfdata(interface);
	241	if (!dev) {
	242	usb_dbg(interface, "disconnect failed - no dev");
	243	return;
	244	}
	245
	246	if (dev->hwrng_registered)
	247	hwrng_unregister(&dev->hwrng);
	248
	249	usb_deregister_dev(interface, &chaoskey_class);
	250
	251	usb_set_intfdata(interface, NULL);
	252	mutex_lock(&dev->lock);
	253
	254	dev->present = 0;
0ca10122	255	usb_poison_urb(dev->urb);
66e3e591 KP	256
	257	if (!dev->open) {
	258	mutex_unlock(&dev->lock);
	259	chaoskey_free(dev);
	260	} else
	261	mutex_unlock(&dev->lock);
	262
	263	usb_dbg(interface, "disconnect done");
	264	}
	265
	266	static int chaoskey_open(struct inode inode, struct file file)
	267	{
	268	struct chaoskey *dev;
	269	struct usb_interface *interface;
	270
	271	/* get the interface from minor number and driver information */
	272	interface = usb_find_interface(&chaoskey_driver, iminor(inode));
	273	if (!interface)
	274	return -ENODEV;
	275
	276	usb_dbg(interface, "open");
	277
	278	dev = usb_get_intfdata(interface);
	279	if (!dev) {
	280	usb_dbg(interface, "open (dev)");
	281	return -ENODEV;
	282	}
	283
	284	file->private_data = dev;
	285	mutex_lock(&dev->lock);
	286	++dev->open;
	287	mutex_unlock(&dev->lock);
	288
	289	usb_dbg(interface, "open success");
	290	return 0;
	291	}
	292
	293	static int chaoskey_release(struct inode inode, struct file file)
	294	{
	295	struct chaoskey *dev = file->private_data;
	296	struct usb_interface *interface;
	297
	298	if (dev == NULL)
	299	return -ENODEV;
	300
	301	interface = dev->interface;
	302
	303	usb_dbg(interface, "release");
	304
	305	mutex_lock(&dev->lock);
	306
	307	usb_dbg(interface, "open count at release is %d", dev->open);
	308
	309	if (dev->open <= 0) {
	310	usb_dbg(interface, "invalid open count (%d)", dev->open);
	311	mutex_unlock(&dev->lock);
	312	return -ENODEV;
	313	}
	314
	315	--dev->open;
	316
	317	if (!dev->present) {
	318	if (dev->open == 0) {
	319	mutex_unlock(&dev->lock);
320	chaoskey_free(dev);
321	} else
322	mutex_unlock(&dev->lock);
323	} else
324	mutex_unlock(&dev->lock);
325
326	usb_dbg(interface, "release success");
327	return 0;
328	}
329
0ca10122 ON	330	static void chaos_read_callback(struct urb *urb)
	331	{
	332	struct chaoskey *dev = urb->context;
	333	int status = urb->status;
	334
	335	usb_dbg(dev->interface, "callback status (%d)", status);
	336
	337	if (status == 0)
	338	dev->valid = urb->actual_length;
	339	else
	340	dev->valid = 0;
	341
	342	dev->used = 0;
	343
	344	/* must be seen first before validity is announced */
	345	smp_wmb();
	346
	347	dev->reading = false;
	348	wake_up(&dev->wait_q);
	349	}
	350
66e3e591 KP	351	/* Fill the buffer. Called with dev->lock held
	352	*/
	353	static int _chaoskey_fill(struct chaoskey *dev)
	354	{
	355	DEFINE_WAIT(wait);
	356	int result;
e4a886e8	357	bool started;
66e3e591 KP	358
	359	usb_dbg(dev->interface, "fill");
	360
	361	/* Return immediately if someone called before the buffer was
	362	* empty */
	363	if (dev->valid != dev->used) {
	364	usb_dbg(dev->interface, "not empty yet (valid %d used %d)",
	365	dev->valid, dev->used);
	366	return 0;
	367	}
	368
	369	/* Bail if the device has been removed */
	370	if (!dev->present) {
	371	usb_dbg(dev->interface, "device not present");
	372	return -ENODEV;
	373	}
	374
	375	/* Make sure the device is awake */
	376	result = usb_autopm_get_interface(dev->interface);
	377	if (result) {
	378	usb_dbg(dev->interface, "wakeup failed (result %d)", result);
	379	return result;
	380	}
	381
0ca10122 ON	382	dev->reading = true;
	383	result = usb_submit_urb(dev->urb, GFP_KERNEL);
	384	if (result < 0) {
	385	result = usb_translate_errors(result);
	386	dev->reading = false;
	387	goto out;
	388	}
	389
e4a886e8 BH	390	/* The first read on the Alea takes a little under 2 seconds.
	391	* Reads after the first read take only a few microseconds
	392	* though. Presumably the entropy-generating circuit needs
	393	* time to ramp up. So, we wait longer on the first read.
	394	*/
	395	started = dev->reads_started;
	396	dev->reads_started = true;
0ca10122 ON	397	result = wait_event_interruptible_timeout(
	398	dev->wait_q,
	399	!dev->reading,
e4a886e8	400	(started ? NAK_TIMEOUT : ALEA_FIRST_TIMEOUT) );
66e3e591	401
0ca10122 ON	402	if (result < 0)
	403	goto out;
	404
	405	if (result == 0)
	406	result = -ETIMEDOUT;
	407	else
	408	result = dev->valid;
	409	out:
66e3e591 KP	410	/* Let the device go back to sleep eventually */
	411	usb_autopm_put_interface(dev->interface);
	412
0ca10122	413	usb_dbg(dev->interface, "read %d bytes", dev->valid);
66e3e591 KP	414
	415	return result;
	416	}
	417
	418	static ssize_t chaoskey_read(struct file *file,
	419	char __user *buffer,
	420	size_t count,
	421	loff_t *ppos)
	422	{
	423	struct chaoskey *dev;
	424	ssize_t read_count = 0;
	425	int this_time;
	426	int result = 0;
	427	unsigned long remain;
	428
	429	dev = file->private_data;
	430
	431	if (dev == NULL \|\| !dev->present)
	432	return -ENODEV;
	433
	434	usb_dbg(dev->interface, "read %zu", count);
	435
	436	while (count > 0) {
	437
	438	/* Grab the rng_lock briefly to ensure that the hwrng interface
	439	* gets priority over other user access
	440	*/
	441	result = mutex_lock_interruptible(&dev->rng_lock);
	442	if (result)
	443	goto bail;
	444	mutex_unlock(&dev->rng_lock);
	445
	446	result = mutex_lock_interruptible(&dev->lock);
	447	if (result)
	448	goto bail;
	449	if (dev->valid == dev->used) {
	450	result = _chaoskey_fill(dev);
0ca10122	451	if (result < 0) {
66e3e591 KP	452	mutex_unlock(&dev->lock);
	453	goto bail;
	454	}
	455	}
	456
	457	this_time = dev->valid - dev->used;
	458	if (this_time > count)
	459	this_time = count;
	460
	461	remain = copy_to_user(buffer, dev->buf + dev->used, this_time);
	462	if (remain) {
	463	result = -EFAULT;
	464
	465	/* Consume the bytes that were copied so we don't leak
	466	* data to user space
	467	*/
	468	dev->used += this_time - remain;
	469	mutex_unlock(&dev->lock);
	470	goto bail;
	471	}
	472
	473	count -= this_time;
	474	read_count += this_time;
	475	buffer += this_time;
	476	dev->used += this_time;
	477	mutex_unlock(&dev->lock);
	478	}
	479	bail:
	480	if (read_count) {
	481	usb_dbg(dev->interface, "read %zu bytes", read_count);
	482	return read_count;
	483	}
	484	usb_dbg(dev->interface, "empty read, result %d", result);
0ca10122 ON	485	if (result == -ETIMEDOUT)
0ca10122 ON	486	result = -EAGAIN;
66e3e591 KP	487	return result;
	488	}
	489
	490	static int chaoskey_rng_read(struct hwrng rng, void data,
	491	size_t max, bool wait)
	492	{
	493	struct chaoskey *dev = container_of(rng, struct chaoskey, hwrng);
	494	int this_time;
	495
	496	usb_dbg(dev->interface, "rng_read max %zu wait %d", max, wait);
	497
	498	if (!dev->present) {
	499	usb_dbg(dev->interface, "device not present");
	500	return 0;
	501	}
	502
	503	/* Hold the rng_lock until we acquire the device lock so that
	504	* this operation gets priority over other user access to the
	505	* device
	506	*/
	507	mutex_lock(&dev->rng_lock);
	508
	509	mutex_lock(&dev->lock);
	510
	511	mutex_unlock(&dev->rng_lock);
	512
	513	/* Try to fill the buffer if empty. It doesn't actually matter
	514	* if _chaoskey_fill works; we'll just return zero bytes as
	515	* the buffer will still be empty
	516	*/
	517	if (dev->valid == dev->used)
	518	(void) _chaoskey_fill(dev);
	519
	520	this_time = dev->valid - dev->used;
	521	if (this_time > max)
	522	this_time = max;
	523
1d5c47f5	524	memcpy(data, dev->buf + dev->used, this_time);
66e3e591 KP	525
	526	dev->used += this_time;
	527
	528	mutex_unlock(&dev->lock);
	529
	530	usb_dbg(dev->interface, "rng_read this_time %d\n", this_time);
	531	return this_time;
	532	}
	533
	534	#ifdef CONFIG_PM
	535	static int chaoskey_suspend(struct usb_interface *interface,
	536	pm_message_t message)
	537	{
	538	usb_dbg(interface, "suspend");
	539	return 0;
	540	}
	541
	542	static int chaoskey_resume(struct usb_interface *interface)
	543	{
	544	usb_dbg(interface, "resume");
	545	return 0;
	546	}
	547	#else
	548	#define chaoskey_suspend NULL
	549	#define chaoskey_resume NULL
	550	#endif
	551
	552	/* file operation pointers */
	553	static const struct file_operations chaoskey_fops = {
	554	.owner = THIS_MODULE,
	555	.read = chaoskey_read,
	556	.open = chaoskey_open,
	557	.release = chaoskey_release,
	558	.llseek = default_llseek,
	559	};
	560
	561	/* class driver information */
	562	static struct usb_class_driver chaoskey_class = {
	563	.name = "chaoskey%d",
	564	.fops = &chaoskey_fops,
	565	.minor_base = USB_CHAOSKEY_MINOR_BASE,
	566	};
	567
	568	/* usb specific object needed to register this driver with the usb subsystem */
	569	static struct usb_driver chaoskey_driver = {
	570	.name = DRIVER_SHORT,
	571	.probe = chaoskey_probe,
	572	.disconnect = chaoskey_disconnect,
	573	.suspend = chaoskey_suspend,
	574	.resume = chaoskey_resume,
	575	.reset_resume = chaoskey_resume,
	576	.id_table = chaoskey_table,
	577	.supports_autosuspend = 1,
	578	};
	579
	580	module_usb_driver(chaoskey_driver);
	581