[GitHub/mt8127/android_kernel_alcatel_ttab.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 <m@bues.ch>
	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 <linux/slab.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;

static size_t rng_buffer_size(void)
{
	return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;
}

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,
				rng_buffer_size(),
				!(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);

	/* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
	err = -ENOMEM;
	if (!rng_buffer) {
		rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);
		if (!rng_buffer)
			goto out_unlock;
	}

	/* 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);

static void __exit hwrng_exit(void)
{
	mutex_lock(&rng_mutex);
	BUG_ON(current_rng);
	kfree(rng_buffer);
	mutex_unlock(&rng_mutex);
}

module_exit(hwrng_exit);

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
eb032b98	22	Copyright 2006 Michael Buesch <m@bues.ch>
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>
f7f154f1	43	#include <linux/slab.h>
844dd05f MB	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;
f7f154f1 RR	56	static u8 *rng_buffer;
	57
	58	static size_t rng_buffer_size(void)
	59	{
	60	return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;
	61	}
844dd05f MB	62
	63	static inline int hwrng_init(struct hwrng *rng)
	64	{
	65	if (!rng->init)
	66	return 0;
	67	return rng->init(rng);
	68	}
	69
	70	static inline void hwrng_cleanup(struct hwrng *rng)
	71	{
	72	if (rng && rng->cleanup)
	73	rng->cleanup(rng);
	74	}
	75
844dd05f MB	76	static int rng_dev_open(struct inode inode, struct file filp)
	77	{
	78	/* enforce read-only access to this chrdev */
	79	if ((filp->f_mode & FMODE_READ) == 0)
	80	return -EINVAL;
	81	if (filp->f_mode & FMODE_WRITE)
	82	return -EINVAL;
	83	return 0;
	84	}
	85
9996508b IM	86	static inline int rng_get_data(struct hwrng rng, u8 buffer, size_t size,
	87	int wait) {
	88	int present;
	89
	90	if (rng->read)
	91	return rng->read(rng, (void *)buffer, size, wait);
	92
	93	if (rng->data_present)
	94	present = rng->data_present(rng, wait);
	95	else
	96	present = 1;
	97
	98	if (present)
	99	return rng->data_read(rng, (u32 *)buffer);
	100
	101	return 0;
	102	}
	103
844dd05f MB	104	static ssize_t rng_dev_read(struct file filp, char __user buf,
	105	size_t size, loff_t *offp)
	106	{
844dd05f	107	ssize_t ret = 0;
984e976f	108	int err = 0;
9996508b	109	int bytes_read, len;
844dd05f MB	110
844dd05f MB	111	while (size) {
9996508b IM	112	if (mutex_lock_interruptible(&rng_mutex)) {
9996508b IM	113	err = -ERESTARTSYS;
844dd05f	114	goto out;
9996508b IM	115	}
9996508b IM	116
844dd05f	117	if (!current_rng) {
844dd05f	118	err = -ENODEV;
9996508b	119	goto out_unlock;
844dd05f	120	}
984e976f	121
9996508b IM	122	if (!data_avail) {
9996508b IM	123	bytes_read = rng_get_data(current_rng, rng_buffer,
f7f154f1	124	rng_buffer_size(),
9996508b IM	125	!(filp->f_flags & O_NONBLOCK));
	126	if (bytes_read < 0) {
	127	err = bytes_read;
	128	goto out_unlock;
	129	}
	130	data_avail = bytes_read;
893f1128	131	}
844dd05f	132
9996508b IM	133	if (!data_avail) {
	134	if (filp->f_flags & O_NONBLOCK) {
	135	err = -EAGAIN;
	136	goto out_unlock;
	137	}
	138	} else {
	139	len = data_avail;
	140	if (len > size)
	141	len = size;
	142
	143	data_avail -= len;
	144
	145	if (copy_to_user(buf + ret, rng_buffer + data_avail,
	146	len)) {
	147	err = -EFAULT;
	148	goto out_unlock;
	149	}
	150
	151	size -= len;
	152	ret += len;
844dd05f MB	153	}
844dd05f MB	154
9996508b IM	155	mutex_unlock(&rng_mutex);
9996508b IM	156
844dd05f MB	157	if (need_resched())
844dd05f MB	158	schedule_timeout_interruptible(1);
9996508b IM	159
	160	if (signal_pending(current)) {
	161	err = -ERESTARTSYS;
844dd05f	162	goto out;
9996508b	163	}
844dd05f MB	164	}
	165	out:
	166	return ret ? : err;
f5908267 HX	167	out_unlock:
	168	mutex_unlock(&rng_mutex);
	169	goto out;
844dd05f MB	170	}
	171
	172
62322d25	173	static const struct file_operations rng_chrdev_ops = {
844dd05f MB	174	.owner = THIS_MODULE,
	175	.open = rng_dev_open,
	176	.read = rng_dev_read,
6038f373	177	.llseek = noop_llseek,
844dd05f MB	178	};
	179
	180	static struct miscdevice rng_miscdev = {
	181	.minor = RNG_MISCDEV_MINOR,
	182	.name = RNG_MODULE_NAME,
e454cea2	183	.nodename = "hwrng",
844dd05f MB	184	.fops = &rng_chrdev_ops,
	185	};
	186
	187
94fbcded GKH	188	static ssize_t hwrng_attr_current_store(struct device *dev,
94fbcded GKH	189	struct device_attribute *attr,
844dd05f MB	190	const char *buf, size_t len)
	191	{
	192	int err;
	193	struct hwrng *rng;
	194
	195	err = mutex_lock_interruptible(&rng_mutex);
	196	if (err)
	197	return -ERESTARTSYS;
	198	err = -ENODEV;
	199	list_for_each_entry(rng, &rng_list, list) {
	200	if (strcmp(rng->name, buf) == 0) {
	201	if (rng == current_rng) {
	202	err = 0;
	203	break;
	204	}
	205	err = hwrng_init(rng);
	206	if (err)
	207	break;
	208	hwrng_cleanup(current_rng);
	209	current_rng = rng;
	210	err = 0;
	211	break;
	212	}
	213	}
	214	mutex_unlock(&rng_mutex);
	215
	216	return err ? : len;
	217	}
	218
94fbcded GKH	219	static ssize_t hwrng_attr_current_show(struct device *dev,
94fbcded GKH	220	struct device_attribute *attr,
844dd05f MB	221	char *buf)
	222	{
	223	int err;
	224	ssize_t ret;
	225	const char *name = "none";
	226
	227	err = mutex_lock_interruptible(&rng_mutex);
	228	if (err)
	229	return -ERESTARTSYS;
	230	if (current_rng)
	231	name = current_rng->name;
	232	ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
	233	mutex_unlock(&rng_mutex);
	234
	235	return ret;
	236	}
	237
94fbcded GKH	238	static ssize_t hwrng_attr_available_show(struct device *dev,
94fbcded GKH	239	struct device_attribute *attr,
844dd05f MB	240	char *buf)
	241	{
	242	int err;
	243	ssize_t ret = 0;
	244	struct hwrng *rng;
	245
	246	err = mutex_lock_interruptible(&rng_mutex);
	247	if (err)
	248	return -ERESTARTSYS;
	249	buf[0] = '\0';
	250	list_for_each_entry(rng, &rng_list, list) {
	251	strncat(buf, rng->name, PAGE_SIZE - ret - 1);
	252	ret += strlen(rng->name);
	253	strncat(buf, " ", PAGE_SIZE - ret - 1);
	254	ret++;
	255	}
	256	strncat(buf, "\n", PAGE_SIZE - ret - 1);
	257	ret++;
	258	mutex_unlock(&rng_mutex);
	259
	260	return ret;
	261	}
	262
94fbcded GKH	263	static DEVICE_ATTR(rng_current, S_IRUGO \| S_IWUSR,
	264	hwrng_attr_current_show,
	265	hwrng_attr_current_store);
	266	static DEVICE_ATTR(rng_available, S_IRUGO,
	267	hwrng_attr_available_show,
	268	NULL);
844dd05f MB	269
844dd05f MB	270
b844eba2	271	static void unregister_miscdev(void)
844dd05f	272	{
94fbcded GKH	273	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
94fbcded GKH	274	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
b844eba2	275	misc_deregister(&rng_miscdev);
844dd05f MB	276	}
	277
	278	static int register_miscdev(void)
	279	{
	280	int err;
	281
	282	err = misc_register(&rng_miscdev);
	283	if (err)
	284	goto out;
94fbcded GKH	285	err = device_create_file(rng_miscdev.this_device,
94fbcded GKH	286	&dev_attr_rng_current);
844dd05f MB	287	if (err)
844dd05f MB	288	goto err_misc_dereg;
94fbcded GKH	289	err = device_create_file(rng_miscdev.this_device,
94fbcded GKH	290	&dev_attr_rng_available);
844dd05f MB	291	if (err)
	292	goto err_remove_current;
	293	out:
	294	return err;
	295
	296	err_remove_current:
94fbcded	297	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
844dd05f MB	298	err_misc_dereg:
	299	misc_deregister(&rng_miscdev);
	300	goto out;
	301	}
	302
	303	int hwrng_register(struct hwrng *rng)
	304	{
	305	int must_register_misc;
	306	int err = -EINVAL;
	307	struct hwrng old_rng, tmp;
	308
	309	if (rng->name == NULL \|\|
9996508b	310	(rng->data_read == NULL && rng->read == NULL))
844dd05f MB	311	goto out;
	312
	313	mutex_lock(&rng_mutex);
	314
f7f154f1 RR	315	/* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
	316	err = -ENOMEM;
	317	if (!rng_buffer) {
	318	rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);
	319	if (!rng_buffer)
	320	goto out_unlock;
	321	}
	322
844dd05f MB	323	/* Must not register two RNGs with the same name. */
	324	err = -EEXIST;
	325	list_for_each_entry(tmp, &rng_list, list) {
	326	if (strcmp(tmp->name, rng->name) == 0)
	327	goto out_unlock;
	328	}
	329
	330	must_register_misc = (current_rng == NULL);
	331	old_rng = current_rng;
	332	if (!old_rng) {
	333	err = hwrng_init(rng);
	334	if (err)
	335	goto out_unlock;
	336	current_rng = rng;
	337	}
	338	err = 0;
	339	if (must_register_misc) {
	340	err = register_miscdev();
	341	if (err) {
	342	if (!old_rng) {
	343	hwrng_cleanup(rng);
	344	current_rng = NULL;
	345	}
	346	goto out_unlock;
	347	}
	348	}
	349	INIT_LIST_HEAD(&rng->list);
	350	list_add_tail(&rng->list, &rng_list);
	351	out_unlock:
	352	mutex_unlock(&rng_mutex);
	353	out:
	354	return err;
	355	}
	356	EXPORT_SYMBOL_GPL(hwrng_register);
	357
b844eba2	358	void hwrng_unregister(struct hwrng *rng)
844dd05f MB	359	{
	360	int err;
	361
	362	mutex_lock(&rng_mutex);
	363
	364	list_del(&rng->list);
	365	if (current_rng == rng) {
	366	hwrng_cleanup(rng);
	367	if (list_empty(&rng_list)) {
	368	current_rng = NULL;
	369	} else {
	370	current_rng = list_entry(rng_list.prev, struct hwrng, list);
	371	err = hwrng_init(current_rng);
	372	if (err)
	373	current_rng = NULL;
	374	}
	375	}
	376	if (list_empty(&rng_list))
b844eba2	377	unregister_miscdev();
844dd05f MB	378
	379	mutex_unlock(&rng_mutex);
	380	}
b844eba2	381	EXPORT_SYMBOL_GPL(hwrng_unregister);
844dd05f	382
b7d44d94 ST	383	static void __exit hwrng_exit(void)
	384	{
	385	mutex_lock(&rng_mutex);
	386	BUG_ON(current_rng);
	387	kfree(rng_buffer);
	388	mutex_unlock(&rng_mutex);
	389	}
	390
	391	module_exit(hwrng_exit);
844dd05f MB	392
	393	MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
	394	MODULE_LICENSE("GPL");