[mirror_ubuntu-artful-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 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 inline int hwrng_data_present(struct hwrng *rng, int wait)
{
	if (!rng->data_present)
		return 1;
	return rng->data_present(rng, wait);
}

static inline int hwrng_data_read(struct hwrng *rng, u32 *data)
{
	return rng->data_read(rng, data);
}


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;
	cycle_kernel_lock();
	return 0;
}

static ssize_t rng_dev_read(struct file *filp, char __user *buf,
			    size_t size, loff_t *offp)
{
	u32 data;
	ssize_t ret = 0;
	int err = 0;
	int bytes_read;

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

		bytes_read = 0;
		if (hwrng_data_present(current_rng,
				       !(filp->f_flags & O_NONBLOCK)))
			bytes_read = hwrng_data_read(current_rng, &data);
		mutex_unlock(&rng_mutex);

		err = -EAGAIN;
		if (!bytes_read && (filp->f_flags & O_NONBLOCK))
			goto out;
		if (bytes_read < 0) {
			err = bytes_read;
			goto out;
		}

		err = -EFAULT;
		while (bytes_read && size) {
			if (put_user((u8)data, buf++))
				goto out;
			size--;
			ret++;
			bytes_read--;
			data >>= 8;
		}

		if (need_resched())
			schedule_timeout_interruptible(1);
		err = -ERESTARTSYS;
		if (signal_pending(current))
			goto out;
	}
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,
	.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)
		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);
	55
	56
	57	static inline int hwrng_init(struct hwrng *rng)
	58	{
	59	if (!rng->init)
	60	return 0;
	61	return rng->init(rng);
	62	}
	63
	64	static inline void hwrng_cleanup(struct hwrng *rng)
	65	{
	66	if (rng && rng->cleanup)
	67	rng->cleanup(rng);
	68	}
	69
984e976f	70	static inline int hwrng_data_present(struct hwrng *rng, int wait)
844dd05f MB	71	{
	72	if (!rng->data_present)
	73	return 1;
984e976f	74	return rng->data_present(rng, wait);
844dd05f MB	75	}
	76
	77	static inline int hwrng_data_read(struct hwrng rng, u32 data)
	78	{
	79	return rng->data_read(rng, data);
	80	}
	81
	82
	83	static int rng_dev_open(struct inode inode, struct file filp)
	84	{
	85	/* enforce read-only access to this chrdev */
	86	if ((filp->f_mode & FMODE_READ) == 0)
	87	return -EINVAL;
	88	if (filp->f_mode & FMODE_WRITE)
	89	return -EINVAL;
a9c4e8f7	90	cycle_kernel_lock();
844dd05f MB	91	return 0;
	92	}
	93
	94	static ssize_t rng_dev_read(struct file filp, char __user buf,
	95	size_t size, loff_t *offp)
	96	{
	97	u32 data;
	98	ssize_t ret = 0;
984e976f	99	int err = 0;
844dd05f MB	100	int bytes_read;
	101
	102	while (size) {
	103	err = -ERESTARTSYS;
	104	if (mutex_lock_interruptible(&rng_mutex))
	105	goto out;
	106	if (!current_rng) {
	107	mutex_unlock(&rng_mutex);
	108	err = -ENODEV;
	109	goto out;
	110	}
984e976f	111
844dd05f	112	bytes_read = 0;
984e976f PM	113	if (hwrng_data_present(current_rng,
984e976f PM	114	!(filp->f_flags & O_NONBLOCK)))
844dd05f MB	115	bytes_read = hwrng_data_read(current_rng, &data);
	116	mutex_unlock(&rng_mutex);
	117
	118	err = -EAGAIN;
	119	if (!bytes_read && (filp->f_flags & O_NONBLOCK))
	120	goto out;
893f1128 RW	121	if (bytes_read < 0) {
	122	err = bytes_read;
	123	goto out;
	124	}
844dd05f MB	125
	126	err = -EFAULT;
	127	while (bytes_read && size) {
	128	if (put_user((u8)data, buf++))
	129	goto out;
	130	size--;
	131	ret++;
	132	bytes_read--;
	133	data >>= 8;
	134	}
	135
	136	if (need_resched())
	137	schedule_timeout_interruptible(1);
	138	err = -ERESTARTSYS;
	139	if (signal_pending(current))
	140	goto out;
	141	}
	142	out:
	143	return ret ? : err;
	144	}
	145
	146
62322d25	147	static const struct file_operations rng_chrdev_ops = {
844dd05f MB	148	.owner = THIS_MODULE,
	149	.open = rng_dev_open,
	150	.read = rng_dev_read,
	151	};
	152
	153	static struct miscdevice rng_miscdev = {
	154	.minor = RNG_MISCDEV_MINOR,
	155	.name = RNG_MODULE_NAME,
	156	.fops = &rng_chrdev_ops,
	157	};
	158
	159
94fbcded GKH	160	static ssize_t hwrng_attr_current_store(struct device *dev,
94fbcded GKH	161	struct device_attribute *attr,
844dd05f MB	162	const char *buf, size_t len)
	163	{
	164	int err;
	165	struct hwrng *rng;
	166
	167	err = mutex_lock_interruptible(&rng_mutex);
	168	if (err)
	169	return -ERESTARTSYS;
	170	err = -ENODEV;
	171	list_for_each_entry(rng, &rng_list, list) {
	172	if (strcmp(rng->name, buf) == 0) {
	173	if (rng == current_rng) {
	174	err = 0;
	175	break;
	176	}
	177	err = hwrng_init(rng);
	178	if (err)
	179	break;
	180	hwrng_cleanup(current_rng);
	181	current_rng = rng;
	182	err = 0;
	183	break;
	184	}
	185	}
	186	mutex_unlock(&rng_mutex);
	187
	188	return err ? : len;
	189	}
	190
94fbcded GKH	191	static ssize_t hwrng_attr_current_show(struct device *dev,
94fbcded GKH	192	struct device_attribute *attr,
844dd05f MB	193	char *buf)
	194	{
	195	int err;
	196	ssize_t ret;
	197	const char *name = "none";
	198
	199	err = mutex_lock_interruptible(&rng_mutex);
	200	if (err)
	201	return -ERESTARTSYS;
	202	if (current_rng)
	203	name = current_rng->name;
	204	ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
	205	mutex_unlock(&rng_mutex);
	206
	207	return ret;
	208	}
	209
94fbcded GKH	210	static ssize_t hwrng_attr_available_show(struct device *dev,
94fbcded GKH	211	struct device_attribute *attr,
844dd05f MB	212	char *buf)
	213	{
	214	int err;
	215	ssize_t ret = 0;
	216	struct hwrng *rng;
	217
	218	err = mutex_lock_interruptible(&rng_mutex);
	219	if (err)
	220	return -ERESTARTSYS;
	221	buf[0] = '\0';
	222	list_for_each_entry(rng, &rng_list, list) {
	223	strncat(buf, rng->name, PAGE_SIZE - ret - 1);
	224	ret += strlen(rng->name);
	225	strncat(buf, " ", PAGE_SIZE - ret - 1);
	226	ret++;
	227	}
	228	strncat(buf, "\n", PAGE_SIZE - ret - 1);
	229	ret++;
	230	mutex_unlock(&rng_mutex);
	231
	232	return ret;
	233	}
	234
94fbcded GKH	235	static DEVICE_ATTR(rng_current, S_IRUGO \| S_IWUSR,
	236	hwrng_attr_current_show,
	237	hwrng_attr_current_store);
	238	static DEVICE_ATTR(rng_available, S_IRUGO,
	239	hwrng_attr_available_show,
	240	NULL);
844dd05f MB	241
844dd05f MB	242
b844eba2	243	static void unregister_miscdev(void)
844dd05f	244	{
94fbcded GKH	245	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
94fbcded GKH	246	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
b844eba2	247	misc_deregister(&rng_miscdev);
844dd05f MB	248	}
	249
	250	static int register_miscdev(void)
	251	{
	252	int err;
	253
	254	err = misc_register(&rng_miscdev);
	255	if (err)
	256	goto out;
94fbcded GKH	257	err = device_create_file(rng_miscdev.this_device,
94fbcded GKH	258	&dev_attr_rng_current);
844dd05f MB	259	if (err)
844dd05f MB	260	goto err_misc_dereg;
94fbcded GKH	261	err = device_create_file(rng_miscdev.this_device,
94fbcded GKH	262	&dev_attr_rng_available);
844dd05f MB	263	if (err)
	264	goto err_remove_current;
	265	out:
	266	return err;
	267
	268	err_remove_current:
94fbcded	269	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
844dd05f MB	270	err_misc_dereg:
	271	misc_deregister(&rng_miscdev);
	272	goto out;
	273	}
	274
	275	int hwrng_register(struct hwrng *rng)
	276	{
	277	int must_register_misc;
	278	int err = -EINVAL;
	279	struct hwrng old_rng, tmp;
	280
	281	if (rng->name == NULL \|\|
	282	rng->data_read == NULL)
	283	goto out;
	284
	285	mutex_lock(&rng_mutex);
	286
	287	/* Must not register two RNGs with the same name. */
	288	err = -EEXIST;
	289	list_for_each_entry(tmp, &rng_list, list) {
	290	if (strcmp(tmp->name, rng->name) == 0)
	291	goto out_unlock;
	292	}
	293
	294	must_register_misc = (current_rng == NULL);
	295	old_rng = current_rng;
	296	if (!old_rng) {
	297	err = hwrng_init(rng);
	298	if (err)
	299	goto out_unlock;
	300	current_rng = rng;
	301	}
	302	err = 0;
	303	if (must_register_misc) {
	304	err = register_miscdev();
	305	if (err) {
	306	if (!old_rng) {
	307	hwrng_cleanup(rng);
	308	current_rng = NULL;
	309	}
	310	goto out_unlock;
	311	}
	312	}
	313	INIT_LIST_HEAD(&rng->list);
	314	list_add_tail(&rng->list, &rng_list);
	315	out_unlock:
	316	mutex_unlock(&rng_mutex);
	317	out:
	318	return err;
	319	}
	320	EXPORT_SYMBOL_GPL(hwrng_register);
	321
b844eba2	322	void hwrng_unregister(struct hwrng *rng)
844dd05f MB	323	{
	324	int err;
	325
	326	mutex_lock(&rng_mutex);
	327
	328	list_del(&rng->list);
	329	if (current_rng == rng) {
	330	hwrng_cleanup(rng);
	331	if (list_empty(&rng_list)) {
	332	current_rng = NULL;
	333	} else {
	334	current_rng = list_entry(rng_list.prev, struct hwrng, list);
	335	err = hwrng_init(current_rng);
	336	if (err)
	337	current_rng = NULL;
	338	}
	339	}
	340	if (list_empty(&rng_list))
b844eba2	341	unregister_miscdev();
844dd05f MB	342
	343	mutex_unlock(&rng_mutex);
	344	}
b844eba2	345	EXPORT_SYMBOL_GPL(hwrng_unregister);
844dd05f MB	346
	347
	348	MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
	349	MODULE_LICENSE("GPL");