2 Added support for the AMD Geode LX RNG
3 (c) Copyright 2004-2005 Advanced Micro Devices, Inc.
7 Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
8 (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>
12 Hardware driver for the AMD 768 Random Number Generator (RNG)
13 (c) Copyright 2001 Red Hat Inc <alan@redhat.com>
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>
22 Copyright 2006 Michael Buesch <mbuesch@freenet.de>
23 Copyright 2005 (c) MontaVista Software, Inc.
25 Please read Documentation/hw_random.txt for details on use.
27 ----------------------------------------------------------
28 This software may be used and distributed according to the terms
29 of the GNU General Public License, incorporated herein by reference.
34 #include <linux/device.h>
35 #include <linux/hw_random.h>
36 #include <linux/module.h>
37 #include <linux/kernel.h>
39 #include <linux/sched.h>
40 #include <linux/smp_lock.h>
41 #include <linux/init.h>
42 #include <linux/miscdevice.h>
43 #include <linux/delay.h>
44 #include <asm/uaccess.h>
47 #define RNG_MODULE_NAME "hw_random"
48 #define PFX RNG_MODULE_NAME ": "
49 #define RNG_MISCDEV_MINOR 183 /* official */
52 static struct hwrng
*current_rng
;
53 static LIST_HEAD(rng_list
);
54 static DEFINE_MUTEX(rng_mutex
);
57 static inline int hwrng_init(struct hwrng
*rng
)
61 return rng
->init(rng
);
64 static inline void hwrng_cleanup(struct hwrng
*rng
)
66 if (rng
&& rng
->cleanup
)
70 static inline int hwrng_data_present(struct hwrng
*rng
, int wait
)
72 if (!rng
->data_present
)
74 return rng
->data_present(rng
, wait
);
77 static inline int hwrng_data_read(struct hwrng
*rng
, u32
*data
)
79 return rng
->data_read(rng
, data
);
83 static int rng_dev_open(struct inode
*inode
, struct file
*filp
)
85 /* enforce read-only access to this chrdev */
86 if ((filp
->f_mode
& FMODE_READ
) == 0)
88 if (filp
->f_mode
& FMODE_WRITE
)
94 static ssize_t
rng_dev_read(struct file
*filp
, char __user
*buf
,
95 size_t size
, loff_t
*offp
)
104 if (mutex_lock_interruptible(&rng_mutex
))
107 mutex_unlock(&rng_mutex
);
113 if (hwrng_data_present(current_rng
,
114 !(filp
->f_flags
& O_NONBLOCK
)))
115 bytes_read
= hwrng_data_read(current_rng
, &data
);
116 mutex_unlock(&rng_mutex
);
119 if (!bytes_read
&& (filp
->f_flags
& O_NONBLOCK
))
121 if (bytes_read
< 0) {
127 while (bytes_read
&& size
) {
128 if (put_user((u8
)data
, buf
++))
137 schedule_timeout_interruptible(1);
139 if (signal_pending(current
))
147 static const struct file_operations rng_chrdev_ops
= {
148 .owner
= THIS_MODULE
,
149 .open
= rng_dev_open
,
150 .read
= rng_dev_read
,
153 static struct miscdevice rng_miscdev
= {
154 .minor
= RNG_MISCDEV_MINOR
,
155 .name
= RNG_MODULE_NAME
,
156 .fops
= &rng_chrdev_ops
,
160 static ssize_t
hwrng_attr_current_store(struct device
*dev
,
161 struct device_attribute
*attr
,
162 const char *buf
, size_t len
)
167 err
= mutex_lock_interruptible(&rng_mutex
);
171 list_for_each_entry(rng
, &rng_list
, list
) {
172 if (strcmp(rng
->name
, buf
) == 0) {
173 if (rng
== current_rng
) {
177 err
= hwrng_init(rng
);
180 hwrng_cleanup(current_rng
);
186 mutex_unlock(&rng_mutex
);
191 static ssize_t
hwrng_attr_current_show(struct device
*dev
,
192 struct device_attribute
*attr
,
197 const char *name
= "none";
199 err
= mutex_lock_interruptible(&rng_mutex
);
203 name
= current_rng
->name
;
204 ret
= snprintf(buf
, PAGE_SIZE
, "%s\n", name
);
205 mutex_unlock(&rng_mutex
);
210 static ssize_t
hwrng_attr_available_show(struct device
*dev
,
211 struct device_attribute
*attr
,
218 err
= mutex_lock_interruptible(&rng_mutex
);
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);
228 strncat(buf
, "\n", PAGE_SIZE
- ret
- 1);
230 mutex_unlock(&rng_mutex
);
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
,
243 static void unregister_miscdev(void)
245 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_available
);
246 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_current
);
247 misc_deregister(&rng_miscdev
);
250 static int register_miscdev(void)
254 err
= misc_register(&rng_miscdev
);
257 err
= device_create_file(rng_miscdev
.this_device
,
258 &dev_attr_rng_current
);
261 err
= device_create_file(rng_miscdev
.this_device
,
262 &dev_attr_rng_available
);
264 goto err_remove_current
;
269 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_current
);
271 misc_deregister(&rng_miscdev
);
275 int hwrng_register(struct hwrng
*rng
)
277 int must_register_misc
;
279 struct hwrng
*old_rng
, *tmp
;
281 if (rng
->name
== NULL
||
282 rng
->data_read
== NULL
)
285 mutex_lock(&rng_mutex
);
287 /* Must not register two RNGs with the same name. */
289 list_for_each_entry(tmp
, &rng_list
, list
) {
290 if (strcmp(tmp
->name
, rng
->name
) == 0)
294 must_register_misc
= (current_rng
== NULL
);
295 old_rng
= current_rng
;
297 err
= hwrng_init(rng
);
303 if (must_register_misc
) {
304 err
= register_miscdev();
313 INIT_LIST_HEAD(&rng
->list
);
314 list_add_tail(&rng
->list
, &rng_list
);
316 mutex_unlock(&rng_mutex
);
320 EXPORT_SYMBOL_GPL(hwrng_register
);
322 void hwrng_unregister(struct hwrng
*rng
)
326 mutex_lock(&rng_mutex
);
328 list_del(&rng
->list
);
329 if (current_rng
== rng
) {
331 if (list_empty(&rng_list
)) {
334 current_rng
= list_entry(rng_list
.prev
, struct hwrng
, list
);
335 err
= hwrng_init(current_rng
);
340 if (list_empty(&rng_list
))
341 unregister_miscdev();
343 mutex_unlock(&rng_mutex
);
345 EXPORT_SYMBOL_GPL(hwrng_unregister
);
348 MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
349 MODULE_LICENSE("GPL");