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 <m@bues.ch>
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/miscdevice.h>
41 #include <linux/delay.h>
42 #include <linux/slab.h>
43 #include <linux/random.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
);
55 static int data_avail
;
56 static u8
*rng_buffer
;
58 static inline int rng_get_data(struct hwrng
*rng
, u8
*buffer
, size_t size
,
61 static size_t rng_buffer_size(void)
63 return SMP_CACHE_BYTES
< 32 ? 32 : SMP_CACHE_BYTES
;
66 static void add_early_randomness(struct hwrng
*rng
)
68 unsigned char bytes
[16];
72 * Currently only virtio-rng cannot return data during device
73 * probe, and that's handled in virtio-rng.c itself. If there
74 * are more such devices, this call to rng_get_data can be
75 * made conditional here instead of doing it per-device.
77 bytes_read
= rng_get_data(rng
, bytes
, sizeof(bytes
), 1);
79 add_device_randomness(bytes
, bytes_read
);
82 static inline int hwrng_init(struct hwrng
*rng
)
91 add_early_randomness(rng
);
95 static inline void hwrng_cleanup(struct hwrng
*rng
)
97 if (rng
&& rng
->cleanup
)
101 static int rng_dev_open(struct inode
*inode
, struct file
*filp
)
103 /* enforce read-only access to this chrdev */
104 if ((filp
->f_mode
& FMODE_READ
) == 0)
106 if (filp
->f_mode
& FMODE_WRITE
)
111 static inline int rng_get_data(struct hwrng
*rng
, u8
*buffer
, size_t size
,
116 return rng
->read(rng
, (void *)buffer
, size
, wait
);
118 if (rng
->data_present
)
119 present
= rng
->data_present(rng
, wait
);
124 return rng
->data_read(rng
, (u32
*)buffer
);
129 static ssize_t
rng_dev_read(struct file
*filp
, char __user
*buf
,
130 size_t size
, loff_t
*offp
)
137 if (mutex_lock_interruptible(&rng_mutex
)) {
148 bytes_read
= rng_get_data(current_rng
, rng_buffer
,
150 !(filp
->f_flags
& O_NONBLOCK
));
151 if (bytes_read
< 0) {
155 data_avail
= bytes_read
;
159 if (filp
->f_flags
& O_NONBLOCK
) {
170 if (copy_to_user(buf
+ ret
, rng_buffer
+ data_avail
,
180 mutex_unlock(&rng_mutex
);
183 schedule_timeout_interruptible(1);
185 if (signal_pending(current
)) {
193 mutex_unlock(&rng_mutex
);
198 static const struct file_operations rng_chrdev_ops
= {
199 .owner
= THIS_MODULE
,
200 .open
= rng_dev_open
,
201 .read
= rng_dev_read
,
202 .llseek
= noop_llseek
,
205 static struct miscdevice rng_miscdev
= {
206 .minor
= RNG_MISCDEV_MINOR
,
207 .name
= RNG_MODULE_NAME
,
209 .fops
= &rng_chrdev_ops
,
213 static ssize_t
hwrng_attr_current_store(struct device
*dev
,
214 struct device_attribute
*attr
,
215 const char *buf
, size_t len
)
220 err
= mutex_lock_interruptible(&rng_mutex
);
224 list_for_each_entry(rng
, &rng_list
, list
) {
225 if (strcmp(rng
->name
, buf
) == 0) {
226 if (rng
== current_rng
) {
230 err
= hwrng_init(rng
);
233 hwrng_cleanup(current_rng
);
239 mutex_unlock(&rng_mutex
);
244 static ssize_t
hwrng_attr_current_show(struct device
*dev
,
245 struct device_attribute
*attr
,
250 const char *name
= "none";
252 err
= mutex_lock_interruptible(&rng_mutex
);
256 name
= current_rng
->name
;
257 ret
= snprintf(buf
, PAGE_SIZE
, "%s\n", name
);
258 mutex_unlock(&rng_mutex
);
263 static ssize_t
hwrng_attr_available_show(struct device
*dev
,
264 struct device_attribute
*attr
,
271 err
= mutex_lock_interruptible(&rng_mutex
);
275 list_for_each_entry(rng
, &rng_list
, list
) {
276 strncat(buf
, rng
->name
, PAGE_SIZE
- ret
- 1);
277 ret
+= strlen(rng
->name
);
278 strncat(buf
, " ", PAGE_SIZE
- ret
- 1);
281 strncat(buf
, "\n", PAGE_SIZE
- ret
- 1);
283 mutex_unlock(&rng_mutex
);
288 static DEVICE_ATTR(rng_current
, S_IRUGO
| S_IWUSR
,
289 hwrng_attr_current_show
,
290 hwrng_attr_current_store
);
291 static DEVICE_ATTR(rng_available
, S_IRUGO
,
292 hwrng_attr_available_show
,
296 static void unregister_miscdev(void)
298 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_available
);
299 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_current
);
300 misc_deregister(&rng_miscdev
);
303 static int register_miscdev(void)
307 err
= misc_register(&rng_miscdev
);
310 err
= device_create_file(rng_miscdev
.this_device
,
311 &dev_attr_rng_current
);
314 err
= device_create_file(rng_miscdev
.this_device
,
315 &dev_attr_rng_available
);
317 goto err_remove_current
;
322 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_current
);
324 misc_deregister(&rng_miscdev
);
328 int hwrng_register(struct hwrng
*rng
)
331 struct hwrng
*old_rng
, *tmp
;
333 if (rng
->name
== NULL
||
334 (rng
->data_read
== NULL
&& rng
->read
== NULL
))
337 mutex_lock(&rng_mutex
);
339 /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
342 rng_buffer
= kmalloc(rng_buffer_size(), GFP_KERNEL
);
347 /* Must not register two RNGs with the same name. */
349 list_for_each_entry(tmp
, &rng_list
, list
) {
350 if (strcmp(tmp
->name
, rng
->name
) == 0)
354 old_rng
= current_rng
;
356 err
= hwrng_init(rng
);
363 err
= register_miscdev();
370 INIT_LIST_HEAD(&rng
->list
);
371 list_add_tail(&rng
->list
, &rng_list
);
373 if (old_rng
&& !rng
->init
) {
375 * Use a new device's input to add some randomness to
376 * the system. If this rng device isn't going to be
377 * used right away, its init function hasn't been
378 * called yet; so only use the randomness from devices
379 * that don't need an init callback.
381 add_early_randomness(rng
);
385 mutex_unlock(&rng_mutex
);
389 EXPORT_SYMBOL_GPL(hwrng_register
);
391 void hwrng_unregister(struct hwrng
*rng
)
395 mutex_lock(&rng_mutex
);
397 list_del(&rng
->list
);
398 if (current_rng
== rng
) {
400 if (list_empty(&rng_list
)) {
403 current_rng
= list_entry(rng_list
.prev
, struct hwrng
, list
);
404 err
= hwrng_init(current_rng
);
409 if (list_empty(&rng_list
))
410 unregister_miscdev();
412 mutex_unlock(&rng_mutex
);
414 EXPORT_SYMBOL_GPL(hwrng_unregister
);
416 static void __exit
hwrng_exit(void)
418 mutex_lock(&rng_mutex
);
421 mutex_unlock(&rng_mutex
);
424 module_exit(hwrng_exit
);
426 MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
427 MODULE_LICENSE("GPL");