[linux.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 <[email protected]>

 	derived from

        Hardware driver for the AMD 768 Random Number Generator (RNG)
        (c) Copyright 2001 Red Hat Inc <[email protected]>

 	derived from

	Hardware driver for Intel i810 Random Number Generator (RNG)
	Copyright 2000,2001 Jeff Garzik <[email protected]>
	Copyright 2000,2001 Philipp Rumpf <[email protected]>

	Added generic RNG API
	Copyright 2006 Michael Buesch <[email protected]>
	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/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:
	return ret ? : err;
out_unlock:
	mutex_unlock(&rng_mutex);
	goto out;
}


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

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 <[email protected]>
	9
	10	derived from
	11
	12	Hardware driver for the AMD 768 Random Number Generator (RNG)
	13	(c) Copyright 2001 Red Hat Inc <[email protected]>
	14
	15	derived from
	16
	17	Hardware driver for Intel i810 Random Number Generator (RNG)
	18	Copyright 2000,2001 Jeff Garzik <[email protected]>
	19	Copyright 2000,2001 Philipp Rumpf <[email protected]>
	20
	21	Added generic RNG API
eb032b98	22	Copyright 2006 Michael Buesch <[email protected]>
844dd05f MB	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>
844dd05f MB	40	#include <linux/init.h>
	41	#include <linux/miscdevice.h>
	42	#include <linux/delay.h>
	43	#include <asm/uaccess.h>
	44
	45
	46	#define RNG_MODULE_NAME "hw_random"
	47	#define PFX RNG_MODULE_NAME ": "
	48	#define RNG_MISCDEV_MINOR 183 /* official */
	49
	50
	51	static struct hwrng *current_rng;
	52	static LIST_HEAD(rng_list);
	53	static DEFINE_MUTEX(rng_mutex);
9996508b	54	static int data_avail;
eed89d0f IM	55	static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES]
eed89d0f IM	56	__cacheline_aligned;
844dd05f MB	57
	58	static inline int hwrng_init(struct hwrng *rng)
	59	{
	60	if (!rng->init)
	61	return 0;
	62	return rng->init(rng);
	63	}
	64
	65	static inline void hwrng_cleanup(struct hwrng *rng)
	66	{
	67	if (rng && rng->cleanup)
	68	rng->cleanup(rng);
	69	}
	70
844dd05f MB	71	static int rng_dev_open(struct inode inode, struct file filp)
	72	{
	73	/* enforce read-only access to this chrdev */
	74	if ((filp->f_mode & FMODE_READ) == 0)
	75	return -EINVAL;
	76	if (filp->f_mode & FMODE_WRITE)
	77	return -EINVAL;
	78	return 0;
	79	}
	80
9996508b IM	81	static inline int rng_get_data(struct hwrng rng, u8 buffer, size_t size,
	82	int wait) {
	83	int present;
	84
	85	if (rng->read)
	86	return rng->read(rng, (void *)buffer, size, wait);
	87
	88	if (rng->data_present)
	89	present = rng->data_present(rng, wait);
	90	else
	91	present = 1;
	92
	93	if (present)
	94	return rng->data_read(rng, (u32 *)buffer);
	95
	96	return 0;
	97	}
	98
844dd05f MB	99	static ssize_t rng_dev_read(struct file filp, char __user buf,
	100	size_t size, loff_t *offp)
	101	{
844dd05f	102	ssize_t ret = 0;
984e976f	103	int err = 0;
9996508b	104	int bytes_read, len;
844dd05f MB	105
844dd05f MB	106	while (size) {
9996508b IM	107	if (mutex_lock_interruptible(&rng_mutex)) {
9996508b IM	108	err = -ERESTARTSYS;
844dd05f	109	goto out;
9996508b IM	110	}
9996508b IM	111
844dd05f	112	if (!current_rng) {
844dd05f	113	err = -ENODEV;
9996508b	114	goto out_unlock;
844dd05f	115	}
984e976f	116
9996508b IM	117	if (!data_avail) {
	118	bytes_read = rng_get_data(current_rng, rng_buffer,
	119	sizeof(rng_buffer),
	120	!(filp->f_flags & O_NONBLOCK));
	121	if (bytes_read < 0) {
	122	err = bytes_read;
	123	goto out_unlock;
	124	}
	125	data_avail = bytes_read;
893f1128	126	}
844dd05f	127
9996508b IM	128	if (!data_avail) {
	129	if (filp->f_flags & O_NONBLOCK) {
	130	err = -EAGAIN;
	131	goto out_unlock;
	132	}
	133	} else {
	134	len = data_avail;
	135	if (len > size)
	136	len = size;
	137
	138	data_avail -= len;
	139
	140	if (copy_to_user(buf + ret, rng_buffer + data_avail,
	141	len)) {
	142	err = -EFAULT;
	143	goto out_unlock;
	144	}
	145
	146	size -= len;
	147	ret += len;
844dd05f MB	148	}
844dd05f MB	149
9996508b IM	150	mutex_unlock(&rng_mutex);
9996508b IM	151
844dd05f MB	152	if (need_resched())
844dd05f MB	153	schedule_timeout_interruptible(1);
9996508b IM	154
	155	if (signal_pending(current)) {
	156	err = -ERESTARTSYS;
844dd05f	157	goto out;
9996508b	158	}
844dd05f MB	159	}
	160	out:
	161	return ret ? : err;
f5908267 HX	162	out_unlock:
	163	mutex_unlock(&rng_mutex);
	164	goto out;
844dd05f MB	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,
6038f373	172	.llseek = noop_llseek,
844dd05f MB	173	};
	174
	175	static struct miscdevice rng_miscdev = {
	176	.minor = RNG_MISCDEV_MINOR,
	177	.name = RNG_MODULE_NAME,
e454cea2	178	.nodename = "hwrng",
844dd05f MB	179	.fops = &rng_chrdev_ops,
	180	};
	181
	182
94fbcded GKH	183	static ssize_t hwrng_attr_current_store(struct device *dev,
94fbcded GKH	184	struct device_attribute *attr,
844dd05f MB	185	const char *buf, size_t len)
	186	{
	187	int err;
	188	struct hwrng *rng;
	189
	190	err = mutex_lock_interruptible(&rng_mutex);
	191	if (err)
	192	return -ERESTARTSYS;
	193	err = -ENODEV;
	194	list_for_each_entry(rng, &rng_list, list) {
	195	if (strcmp(rng->name, buf) == 0) {
	196	if (rng == current_rng) {
	197	err = 0;
	198	break;
	199	}
	200	err = hwrng_init(rng);
	201	if (err)
	202	break;
	203	hwrng_cleanup(current_rng);
	204	current_rng = rng;
	205	err = 0;
	206	break;
	207	}
	208	}
	209	mutex_unlock(&rng_mutex);
	210
	211	return err ? : len;
	212	}
	213
94fbcded GKH	214	static ssize_t hwrng_attr_current_show(struct device *dev,
94fbcded GKH	215	struct device_attribute *attr,
844dd05f MB	216	char *buf)
	217	{
	218	int err;
	219	ssize_t ret;
	220	const char *name = "none";
	221
	222	err = mutex_lock_interruptible(&rng_mutex);
	223	if (err)
	224	return -ERESTARTSYS;
	225	if (current_rng)
	226	name = current_rng->name;
	227	ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
	228	mutex_unlock(&rng_mutex);
	229
	230	return ret;
	231	}
	232
94fbcded GKH	233	static ssize_t hwrng_attr_available_show(struct device *dev,
94fbcded GKH	234	struct device_attribute *attr,
844dd05f MB	235	char *buf)
	236	{
	237	int err;
	238	ssize_t ret = 0;
	239	struct hwrng *rng;
	240
	241	err = mutex_lock_interruptible(&rng_mutex);
	242	if (err)
	243	return -ERESTARTSYS;
	244	buf[0] = '\0';
	245	list_for_each_entry(rng, &rng_list, list) {
	246	strncat(buf, rng->name, PAGE_SIZE - ret - 1);
	247	ret += strlen(rng->name);
	248	strncat(buf, " ", PAGE_SIZE - ret - 1);
	249	ret++;
	250	}
	251	strncat(buf, "\n", PAGE_SIZE - ret - 1);
	252	ret++;
	253	mutex_unlock(&rng_mutex);
	254
	255	return ret;
	256	}
	257
94fbcded GKH	258	static DEVICE_ATTR(rng_current, S_IRUGO \| S_IWUSR,
	259	hwrng_attr_current_show,
	260	hwrng_attr_current_store);
	261	static DEVICE_ATTR(rng_available, S_IRUGO,
	262	hwrng_attr_available_show,
	263	NULL);
844dd05f MB	264
844dd05f MB	265
b844eba2	266	static void unregister_miscdev(void)
844dd05f	267	{
94fbcded GKH	268	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
94fbcded GKH	269	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
b844eba2	270	misc_deregister(&rng_miscdev);
844dd05f MB	271	}
	272
	273	static int register_miscdev(void)
	274	{
	275	int err;
	276
	277	err = misc_register(&rng_miscdev);
	278	if (err)
	279	goto out;
94fbcded GKH	280	err = device_create_file(rng_miscdev.this_device,
94fbcded GKH	281	&dev_attr_rng_current);
844dd05f MB	282	if (err)
844dd05f MB	283	goto err_misc_dereg;
94fbcded GKH	284	err = device_create_file(rng_miscdev.this_device,
94fbcded GKH	285	&dev_attr_rng_available);
844dd05f MB	286	if (err)
	287	goto err_remove_current;
	288	out:
	289	return err;
	290
	291	err_remove_current:
94fbcded	292	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
844dd05f MB	293	err_misc_dereg:
	294	misc_deregister(&rng_miscdev);
	295	goto out;
	296	}
	297
	298	int hwrng_register(struct hwrng *rng)
	299	{
	300	int must_register_misc;
	301	int err = -EINVAL;
	302	struct hwrng old_rng, tmp;
	303
	304	if (rng->name == NULL \|\|
9996508b	305	(rng->data_read == NULL && rng->read == NULL))
844dd05f MB	306	goto out;
	307
	308	mutex_lock(&rng_mutex);
	309
	310	/* Must not register two RNGs with the same name. */
	311	err = -EEXIST;
	312	list_for_each_entry(tmp, &rng_list, list) {
	313	if (strcmp(tmp->name, rng->name) == 0)
	314	goto out_unlock;
	315	}
	316
	317	must_register_misc = (current_rng == NULL);
	318	old_rng = current_rng;
	319	if (!old_rng) {
	320	err = hwrng_init(rng);
	321	if (err)
	322	goto out_unlock;
	323	current_rng = rng;
	324	}
	325	err = 0;
	326	if (must_register_misc) {
	327	err = register_miscdev();
	328	if (err) {
	329	if (!old_rng) {
	330	hwrng_cleanup(rng);
	331	current_rng = NULL;
	332	}
	333	goto out_unlock;
	334	}
	335	}
	336	INIT_LIST_HEAD(&rng->list);
	337	list_add_tail(&rng->list, &rng_list);
	338	out_unlock:
	339	mutex_unlock(&rng_mutex);
	340	out:
	341	return err;
	342	}
	343	EXPORT_SYMBOL_GPL(hwrng_register);
	344
b844eba2	345	void hwrng_unregister(struct hwrng *rng)
844dd05f MB	346	{
	347	int err;
	348
	349	mutex_lock(&rng_mutex);
	350
	351	list_del(&rng->list);
	352	if (current_rng == rng) {
	353	hwrng_cleanup(rng);
	354	if (list_empty(&rng_list)) {
	355	current_rng = NULL;
	356	} else {
	357	current_rng = list_entry(rng_list.prev, struct hwrng, list);
	358	err = hwrng_init(current_rng);
	359	if (err)
	360	current_rng = NULL;
	361	}
	362	}
	363	if (list_empty(&rng_list))
b844eba2	364	unregister_miscdev();
844dd05f MB	365
	366	mutex_unlock(&rng_mutex);
	367	}
b844eba2	368	EXPORT_SYMBOL_GPL(hwrng_unregister);
844dd05f MB	369
	370
	371	MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
	372	MODULE_LICENSE("GPL");