[mirror_ubuntu-zesty-kernel.git] / drivers / char / hw_random / core.c

/*
        Added support for the AMD Geode LX RNG
	(c) Copyright 2004-2005 Advanced Micro Devices, Inc.

	derived from

 	Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
	(c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>

 	derived from

        Hardware driver for the AMD 768 Random Number Generator (RNG)
        (c) Copyright 2001 Red Hat Inc <alan@redhat.com>

 	derived from

	Hardware driver for Intel i810 Random Number Generator (RNG)
	Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
	Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>

	Added generic RNG API
	Copyright 2006 Michael Buesch <mbuesch@freenet.de>
	Copyright 2005 (c) MontaVista Software, Inc.

	Please read Documentation/hw_random.txt for details on use.

	----------------------------------------------------------
	This software may be used and distributed according to the terms
        of the GNU General Public License, incorporated herein by reference.

 */


#include <linux/device.h>
#include <linux/hw_random.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/delay.h>
#include <asm/uaccess.h>


#define RNG_MODULE_NAME		"hw_random"
#define PFX			RNG_MODULE_NAME ": "
#define RNG_MISCDEV_MINOR	183 /* official */


static struct hwrng *current_rng;
static LIST_HEAD(rng_list);
static DEFINE_MUTEX(rng_mutex);
static int data_avail;
static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES]
	__cacheline_aligned;

static inline int hwrng_init(struct hwrng *rng)
{
	if (!rng->init)
		return 0;
	return rng->init(rng);
}

static inline void hwrng_cleanup(struct hwrng *rng)
{
	if (rng && rng->cleanup)
		rng->cleanup(rng);
}

static int rng_dev_open(struct inode *inode, struct file *filp)
{
	/* enforce read-only access to this chrdev */
	if ((filp->f_mode & FMODE_READ) == 0)
		return -EINVAL;
	if (filp->f_mode & FMODE_WRITE)
		return -EINVAL;
	return 0;
}

static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
			int wait) {
	int present;

	if (rng->read)
		return rng->read(rng, (void *)buffer, size, wait);

	if (rng->data_present)
		present = rng->data_present(rng, wait);
	else
		present = 1;

	if (present)
		return rng->data_read(rng, (u32 *)buffer);

	return 0;
}

static ssize_t rng_dev_read(struct file *filp, char __user *buf,
			    size_t size, loff_t *offp)
{
	ssize_t ret = 0;
	int err = 0;
	int bytes_read, len;

	while (size) {
		if (mutex_lock_interruptible(&rng_mutex)) {
			err = -ERESTARTSYS;
			goto out;
		}

		if (!current_rng) {
			err = -ENODEV;
			goto out_unlock;
		}

		if (!data_avail) {
			bytes_read = rng_get_data(current_rng, rng_buffer,
				sizeof(rng_buffer),
				!(filp->f_flags & O_NONBLOCK));
			if (bytes_read < 0) {
				err = bytes_read;
				goto out_unlock;
			}
			data_avail = bytes_read;
		}

		if (!data_avail) {
			if (filp->f_flags & O_NONBLOCK) {
				err = -EAGAIN;
				goto out_unlock;
			}
		} else {
			len = data_avail;
			if (len > size)
				len = size;

			data_avail -= len;

			if (copy_to_user(buf + ret, rng_buffer + data_avail,
								len)) {
				err = -EFAULT;
				goto out_unlock;
			}

			size -= len;
			ret += len;
		}

		mutex_unlock(&rng_mutex);

		if (need_resched())
			schedule_timeout_interruptible(1);

		if (signal_pending(current)) {
			err = -ERESTARTSYS;
			goto out;
		}
	}
out_unlock:
	mutex_unlock(&rng_mutex);
out:
	return ret ? : err;
}


static const struct file_operations rng_chrdev_ops = {
	.owner		= THIS_MODULE,
	.open		= rng_dev_open,
	.read		= rng_dev_read,
};

static struct miscdevice rng_miscdev = {
	.minor		= RNG_MISCDEV_MINOR,
	.name		= RNG_MODULE_NAME,
	.nodename	= "hwrng",
	.fops		= &rng_chrdev_ops,
};


static ssize_t hwrng_attr_current_store(struct device *dev,
					struct device_attribute *attr,
					const char *buf, size_t len)
{
	int err;
	struct hwrng *rng;

	err = mutex_lock_interruptible(&rng_mutex);
	if (err)
		return -ERESTARTSYS;
	err = -ENODEV;
	list_for_each_entry(rng, &rng_list, list) {
		if (strcmp(rng->name, buf) == 0) {
			if (rng == current_rng) {
				err = 0;
				break;
			}
			err = hwrng_init(rng);
			if (err)
				break;
			hwrng_cleanup(current_rng);
			current_rng = rng;
			err = 0;
			break;
		}
	}
	mutex_unlock(&rng_mutex);

	return err ? : len;
}

static ssize_t hwrng_attr_current_show(struct device *dev,
				       struct device_attribute *attr,
				       char *buf)
{
	int err;
	ssize_t ret;
	const char *name = "none";

	err = mutex_lock_interruptible(&rng_mutex);
	if (err)
		return -ERESTARTSYS;
	if (current_rng)
		name = current_rng->name;
	ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
	mutex_unlock(&rng_mutex);

	return ret;
}

static ssize_t hwrng_attr_available_show(struct device *dev,
					 struct device_attribute *attr,
					 char *buf)
{
	int err;
	ssize_t ret = 0;
	struct hwrng *rng;

	err = mutex_lock_interruptible(&rng_mutex);
	if (err)
		return -ERESTARTSYS;
	buf[0] = '\0';
	list_for_each_entry(rng, &rng_list, list) {
		strncat(buf, rng->name, PAGE_SIZE - ret - 1);
		ret += strlen(rng->name);
		strncat(buf, " ", PAGE_SIZE - ret - 1);
		ret++;
	}
	strncat(buf, "\n", PAGE_SIZE - ret - 1);
	ret++;
	mutex_unlock(&rng_mutex);

	return ret;
}

static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
		   hwrng_attr_current_show,
		   hwrng_attr_current_store);
static DEVICE_ATTR(rng_available, S_IRUGO,
		   hwrng_attr_available_show,
		   NULL);


static void unregister_miscdev(void)
{
	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
	misc_deregister(&rng_miscdev);
}

static int register_miscdev(void)
{
	int err;

	err = misc_register(&rng_miscdev);
	if (err)
		goto out;
	err = device_create_file(rng_miscdev.this_device,
				 &dev_attr_rng_current);
	if (err)
		goto err_misc_dereg;
	err = device_create_file(rng_miscdev.this_device,
				 &dev_attr_rng_available);
	if (err)
		goto err_remove_current;
out:
	return err;

err_remove_current:
	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
err_misc_dereg:
	misc_deregister(&rng_miscdev);
	goto out;
}

int hwrng_register(struct hwrng *rng)
{
	int must_register_misc;
	int err = -EINVAL;
	struct hwrng *old_rng, *tmp;

	if (rng->name == NULL ||
	    (rng->data_read == NULL && rng->read == NULL))
		goto out;

	mutex_lock(&rng_mutex);

	/* Must not register two RNGs with the same name. */
	err = -EEXIST;
	list_for_each_entry(tmp, &rng_list, list) {
		if (strcmp(tmp->name, rng->name) == 0)
			goto out_unlock;
	}

	must_register_misc = (current_rng == NULL);
	old_rng = current_rng;
	if (!old_rng) {
		err = hwrng_init(rng);
		if (err)
			goto out_unlock;
		current_rng = rng;
	}
	err = 0;
	if (must_register_misc) {
		err = register_miscdev();
		if (err) {
			if (!old_rng) {
				hwrng_cleanup(rng);
				current_rng = NULL;
			}
			goto out_unlock;
		}
	}
	INIT_LIST_HEAD(&rng->list);
	list_add_tail(&rng->list, &rng_list);
out_unlock:
	mutex_unlock(&rng_mutex);
out:
	return err;
}
EXPORT_SYMBOL_GPL(hwrng_register);

void hwrng_unregister(struct hwrng *rng)
{
	int err;

	mutex_lock(&rng_mutex);

	list_del(&rng->list);
	if (current_rng == rng) {
		hwrng_cleanup(rng);
		if (list_empty(&rng_list)) {
			current_rng = NULL;
		} else {
			current_rng = list_entry(rng_list.prev, struct hwrng, list);
			err = hwrng_init(current_rng);
			if (err)
				current_rng = NULL;
		}
	}
	if (list_empty(&rng_list))
		unregister_miscdev();

	mutex_unlock(&rng_mutex);
}
EXPORT_SYMBOL_GPL(hwrng_unregister);


MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
MODULE_LICENSE("GPL");
Commit	Line	Data
844dd05f MB	1	/*
	2	Added support for the AMD Geode LX RNG
	3	(c) Copyright 2004-2005 Advanced Micro Devices, Inc.
	4
	5	derived from
	6
	7	Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
	8	(c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>
	9
	10	derived from
	11
	12	Hardware driver for the AMD 768 Random Number Generator (RNG)
	13	(c) Copyright 2001 Red Hat Inc <alan@redhat.com>
	14
	15	derived from
	16
	17	Hardware driver for Intel i810 Random Number Generator (RNG)
	18	Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
	19	Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
	20
	21	Added generic RNG API
	22	Copyright 2006 Michael Buesch <mbuesch@freenet.de>
	23	Copyright 2005 (c) MontaVista Software, Inc.
	24
	25	Please read Documentation/hw_random.txt for details on use.
	26
	27	----------------------------------------------------------
	28	This software may be used and distributed according to the terms
	29	of the GNU General Public License, incorporated herein by reference.
	30
	31	*/
	32
	33
	34	#include <linux/device.h>
	35	#include <linux/hw_random.h>
	36	#include <linux/module.h>
	37	#include <linux/kernel.h>
	38	#include <linux/fs.h>
914e2637	39	#include <linux/sched.h>
a9c4e8f7	40	#include <linux/smp_lock.h>
844dd05f MB	41	#include <linux/init.h>
	42	#include <linux/miscdevice.h>
	43	#include <linux/delay.h>
	44	#include <asm/uaccess.h>
	45
	46
	47	#define RNG_MODULE_NAME "hw_random"
	48	#define PFX RNG_MODULE_NAME ": "
	49	#define RNG_MISCDEV_MINOR 183 /* official */
	50
	51
	52	static struct hwrng *current_rng;
	53	static LIST_HEAD(rng_list);
	54	static DEFINE_MUTEX(rng_mutex);
9996508b	55	static int data_avail;
eed89d0f IM	56	static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES]
eed89d0f IM	57	__cacheline_aligned;
844dd05f MB	58
	59	static inline int hwrng_init(struct hwrng *rng)
	60	{
	61	if (!rng->init)
	62	return 0;
	63	return rng->init(rng);
	64	}
	65
	66	static inline void hwrng_cleanup(struct hwrng *rng)
	67	{
	68	if (rng && rng->cleanup)
	69	rng->cleanup(rng);
	70	}
	71
844dd05f MB	72	static int rng_dev_open(struct inode inode, struct file filp)
	73	{
	74	/* enforce read-only access to this chrdev */
	75	if ((filp->f_mode & FMODE_READ) == 0)
	76	return -EINVAL;
	77	if (filp->f_mode & FMODE_WRITE)
	78	return -EINVAL;
	79	return 0;
	80	}
	81
9996508b IM	82	static inline int rng_get_data(struct hwrng rng, u8 buffer, size_t size,
	83	int wait) {
	84	int present;
	85
	86	if (rng->read)
	87	return rng->read(rng, (void *)buffer, size, wait);
	88
	89	if (rng->data_present)
	90	present = rng->data_present(rng, wait);
	91	else
	92	present = 1;
	93
	94	if (present)
	95	return rng->data_read(rng, (u32 *)buffer);
	96
	97	return 0;
	98	}
	99
844dd05f MB	100	static ssize_t rng_dev_read(struct file filp, char __user buf,
	101	size_t size, loff_t *offp)
	102	{
844dd05f	103	ssize_t ret = 0;
984e976f	104	int err = 0;
9996508b	105	int bytes_read, len;
844dd05f MB	106
844dd05f MB	107	while (size) {
9996508b IM	108	if (mutex_lock_interruptible(&rng_mutex)) {
9996508b IM	109	err = -ERESTARTSYS;
844dd05f	110	goto out;
9996508b IM	111	}
9996508b IM	112
844dd05f	113	if (!current_rng) {
844dd05f	114	err = -ENODEV;
9996508b	115	goto out_unlock;
844dd05f	116	}
984e976f	117
9996508b IM	118	if (!data_avail) {
	119	bytes_read = rng_get_data(current_rng, rng_buffer,
	120	sizeof(rng_buffer),
	121	!(filp->f_flags & O_NONBLOCK));
	122	if (bytes_read < 0) {
	123	err = bytes_read;
	124	goto out_unlock;
	125	}
	126	data_avail = bytes_read;
893f1128	127	}
844dd05f	128
9996508b IM	129	if (!data_avail) {
	130	if (filp->f_flags & O_NONBLOCK) {
	131	err = -EAGAIN;
	132	goto out_unlock;
	133	}
	134	} else {
	135	len = data_avail;
	136	if (len > size)
	137	len = size;
	138
	139	data_avail -= len;
	140
	141	if (copy_to_user(buf + ret, rng_buffer + data_avail,
	142	len)) {
	143	err = -EFAULT;
	144	goto out_unlock;
	145	}
	146
	147	size -= len;
	148	ret += len;
844dd05f MB	149	}
844dd05f MB	150
9996508b IM	151	mutex_unlock(&rng_mutex);
9996508b IM	152
844dd05f MB	153	if (need_resched())
844dd05f MB	154	schedule_timeout_interruptible(1);
9996508b IM	155
	156	if (signal_pending(current)) {
	157	err = -ERESTARTSYS;
844dd05f	158	goto out;
9996508b	159	}
844dd05f	160	}
9996508b IM	161	out_unlock:
9996508b IM	162	mutex_unlock(&rng_mutex);
844dd05f MB	163	out:
	164	return ret ? : err;
	165	}
	166
	167
62322d25	168	static const struct file_operations rng_chrdev_ops = {
844dd05f MB	169	.owner = THIS_MODULE,
	170	.open = rng_dev_open,
	171	.read = rng_dev_read,
	172	};
	173
	174	static struct miscdevice rng_miscdev = {
	175	.minor = RNG_MISCDEV_MINOR,
	176	.name = RNG_MODULE_NAME,
e454cea2	177	.nodename = "hwrng",
844dd05f MB	178	.fops = &rng_chrdev_ops,
	179	};
	180
	181
94fbcded GKH	182	static ssize_t hwrng_attr_current_store(struct device *dev,
94fbcded GKH	183	struct device_attribute *attr,
844dd05f MB	184	const char *buf, size_t len)
	185	{
	186	int err;
	187	struct hwrng *rng;
	188
	189	err = mutex_lock_interruptible(&rng_mutex);
	190	if (err)
	191	return -ERESTARTSYS;
	192	err = -ENODEV;
	193	list_for_each_entry(rng, &rng_list, list) {
	194	if (strcmp(rng->name, buf) == 0) {
	195	if (rng == current_rng) {
	196	err = 0;
	197	break;
	198	}
	199	err = hwrng_init(rng);
	200	if (err)
	201	break;
	202	hwrng_cleanup(current_rng);
	203	current_rng = rng;
	204	err = 0;
	205	break;
	206	}
	207	}
	208	mutex_unlock(&rng_mutex);
	209
	210	return err ? : len;
	211	}
	212
94fbcded GKH	213	static ssize_t hwrng_attr_current_show(struct device *dev,
94fbcded GKH	214	struct device_attribute *attr,
844dd05f MB	215	char *buf)
	216	{
	217	int err;
	218	ssize_t ret;
	219	const char *name = "none";
	220
	221	err = mutex_lock_interruptible(&rng_mutex);
	222	if (err)
	223	return -ERESTARTSYS;
	224	if (current_rng)
	225	name = current_rng->name;
	226	ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
	227	mutex_unlock(&rng_mutex);
	228
	229	return ret;
	230	}
	231
94fbcded GKH	232	static ssize_t hwrng_attr_available_show(struct device *dev,
94fbcded GKH	233	struct device_attribute *attr,
844dd05f MB	234	char *buf)
	235	{
	236	int err;
	237	ssize_t ret = 0;
	238	struct hwrng *rng;
	239
	240	err = mutex_lock_interruptible(&rng_mutex);
	241	if (err)
	242	return -ERESTARTSYS;
	243	buf[0] = '\0';
	244	list_for_each_entry(rng, &rng_list, list) {
	245	strncat(buf, rng->name, PAGE_SIZE - ret - 1);
	246	ret += strlen(rng->name);
	247	strncat(buf, " ", PAGE_SIZE - ret - 1);
	248	ret++;
	249	}
	250	strncat(buf, "\n", PAGE_SIZE - ret - 1);
	251	ret++;
	252	mutex_unlock(&rng_mutex);
	253
	254	return ret;
	255	}
	256
94fbcded GKH	257	static DEVICE_ATTR(rng_current, S_IRUGO \| S_IWUSR,
	258	hwrng_attr_current_show,
	259	hwrng_attr_current_store);
	260	static DEVICE_ATTR(rng_available, S_IRUGO,
	261	hwrng_attr_available_show,
	262	NULL);
844dd05f MB	263
844dd05f MB	264
b844eba2	265	static void unregister_miscdev(void)
844dd05f	266	{
94fbcded GKH	267	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
94fbcded GKH	268	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
b844eba2	269	misc_deregister(&rng_miscdev);
844dd05f MB	270	}
	271
	272	static int register_miscdev(void)
	273	{
	274	int err;
	275
	276	err = misc_register(&rng_miscdev);
	277	if (err)
	278	goto out;
94fbcded GKH	279	err = device_create_file(rng_miscdev.this_device,
94fbcded GKH	280	&dev_attr_rng_current);
844dd05f MB	281	if (err)
844dd05f MB	282	goto err_misc_dereg;
94fbcded GKH	283	err = device_create_file(rng_miscdev.this_device,
94fbcded GKH	284	&dev_attr_rng_available);
844dd05f MB	285	if (err)
	286	goto err_remove_current;
	287	out:
	288	return err;
	289
	290	err_remove_current:
94fbcded	291	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
844dd05f MB	292	err_misc_dereg:
	293	misc_deregister(&rng_miscdev);
	294	goto out;
	295	}
	296
	297	int hwrng_register(struct hwrng *rng)
	298	{
	299	int must_register_misc;
	300	int err = -EINVAL;
	301	struct hwrng old_rng, tmp;
	302
	303	if (rng->name == NULL \|\|
9996508b	304	(rng->data_read == NULL && rng->read == NULL))
844dd05f MB	305	goto out;
	306
	307	mutex_lock(&rng_mutex);
	308
	309	/* Must not register two RNGs with the same name. */
	310	err = -EEXIST;
	311	list_for_each_entry(tmp, &rng_list, list) {
	312	if (strcmp(tmp->name, rng->name) == 0)
	313	goto out_unlock;
	314	}
	315
	316	must_register_misc = (current_rng == NULL);
	317	old_rng = current_rng;
	318	if (!old_rng) {
	319	err = hwrng_init(rng);
	320	if (err)
	321	goto out_unlock;
	322	current_rng = rng;
	323	}
	324	err = 0;
	325	if (must_register_misc) {
	326	err = register_miscdev();
	327	if (err) {
	328	if (!old_rng) {
	329	hwrng_cleanup(rng);
	330	current_rng = NULL;
	331	}
	332	goto out_unlock;
	333	}
	334	}
	335	INIT_LIST_HEAD(&rng->list);
	336	list_add_tail(&rng->list, &rng_list);
	337	out_unlock:
	338	mutex_unlock(&rng_mutex);
	339	out:
	340	return err;
	341	}
	342	EXPORT_SYMBOL_GPL(hwrng_register);
	343
b844eba2	344	void hwrng_unregister(struct hwrng *rng)
844dd05f MB	345	{
	346	int err;
	347
	348	mutex_lock(&rng_mutex);
	349
	350	list_del(&rng->list);
	351	if (current_rng == rng) {
	352	hwrng_cleanup(rng);
	353	if (list_empty(&rng_list)) {
	354	current_rng = NULL;
	355	} else {
	356	current_rng = list_entry(rng_list.prev, struct hwrng, list);
	357	err = hwrng_init(current_rng);
	358	if (err)
	359	current_rng = NULL;
	360	}
	361	}
	362	if (list_empty(&rng_list))
b844eba2	363	unregister_miscdev();
844dd05f MB	364
	365	mutex_unlock(&rng_mutex);
	366	}
b844eba2	367	EXPORT_SYMBOL_GPL(hwrng_unregister);
844dd05f MB	368
	369
	370	MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
	371	MODULE_LICENSE("GPL");