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/init.h>
40 #include <linux/miscdevice.h>
41 #include <linux/delay.h>
42 #include <asm/uaccess.h>
45 #define RNG_MODULE_NAME "hw_random"
46 #define PFX RNG_MODULE_NAME ": "
47 #define RNG_MISCDEV_MINOR 183 /* official */
50 static struct hwrng
*current_rng
;
51 static LIST_HEAD(rng_list
);
52 static DEFINE_MUTEX(rng_mutex
);
55 static inline int hwrng_init(struct hwrng
*rng
)
59 return rng
->init(rng
);
62 static inline void hwrng_cleanup(struct hwrng
*rng
)
64 if (rng
&& rng
->cleanup
)
68 static inline int hwrng_data_present(struct hwrng
*rng
)
70 if (!rng
->data_present
)
72 return rng
->data_present(rng
);
75 static inline int hwrng_data_read(struct hwrng
*rng
, u32
*data
)
77 return rng
->data_read(rng
, data
);
81 static int rng_dev_open(struct inode
*inode
, struct file
*filp
)
83 /* enforce read-only access to this chrdev */
84 if ((filp
->f_mode
& FMODE_READ
) == 0)
86 if (filp
->f_mode
& FMODE_WRITE
)
91 static ssize_t
rng_dev_read(struct file
*filp
, char __user
*buf
,
92 size_t size
, loff_t
*offp
)
102 if (mutex_lock_interruptible(&rng_mutex
))
105 mutex_unlock(&rng_mutex
);
109 if (filp
->f_flags
& O_NONBLOCK
) {
110 data_present
= hwrng_data_present(current_rng
);
112 /* Some RNG require some time between data_reads to gather
113 * new entropy. Poll it.
115 for (i
= 0; i
< 20; i
++) {
116 data_present
= hwrng_data_present(current_rng
);
124 bytes_read
= hwrng_data_read(current_rng
, &data
);
125 mutex_unlock(&rng_mutex
);
128 if (!bytes_read
&& (filp
->f_flags
& O_NONBLOCK
))
132 while (bytes_read
&& size
) {
133 if (put_user((u8
)data
, buf
++))
142 schedule_timeout_interruptible(1);
144 if (signal_pending(current
))
152 static const struct file_operations rng_chrdev_ops
= {
153 .owner
= THIS_MODULE
,
154 .open
= rng_dev_open
,
155 .read
= rng_dev_read
,
158 static struct miscdevice rng_miscdev
= {
159 .minor
= RNG_MISCDEV_MINOR
,
160 .name
= RNG_MODULE_NAME
,
161 .fops
= &rng_chrdev_ops
,
165 static ssize_t
hwrng_attr_current_store(struct device
*dev
,
166 struct device_attribute
*attr
,
167 const char *buf
, size_t len
)
172 err
= mutex_lock_interruptible(&rng_mutex
);
176 list_for_each_entry(rng
, &rng_list
, list
) {
177 if (strcmp(rng
->name
, buf
) == 0) {
178 if (rng
== current_rng
) {
182 err
= hwrng_init(rng
);
185 hwrng_cleanup(current_rng
);
191 mutex_unlock(&rng_mutex
);
196 static ssize_t
hwrng_attr_current_show(struct device
*dev
,
197 struct device_attribute
*attr
,
202 const char *name
= "none";
204 err
= mutex_lock_interruptible(&rng_mutex
);
208 name
= current_rng
->name
;
209 ret
= snprintf(buf
, PAGE_SIZE
, "%s\n", name
);
210 mutex_unlock(&rng_mutex
);
215 static ssize_t
hwrng_attr_available_show(struct device
*dev
,
216 struct device_attribute
*attr
,
223 err
= mutex_lock_interruptible(&rng_mutex
);
227 list_for_each_entry(rng
, &rng_list
, list
) {
228 strncat(buf
, rng
->name
, PAGE_SIZE
- ret
- 1);
229 ret
+= strlen(rng
->name
);
230 strncat(buf
, " ", PAGE_SIZE
- ret
- 1);
233 strncat(buf
, "\n", PAGE_SIZE
- ret
- 1);
235 mutex_unlock(&rng_mutex
);
240 static DEVICE_ATTR(rng_current
, S_IRUGO
| S_IWUSR
,
241 hwrng_attr_current_show
,
242 hwrng_attr_current_store
);
243 static DEVICE_ATTR(rng_available
, S_IRUGO
,
244 hwrng_attr_available_show
,
248 static void unregister_miscdev(void)
250 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_available
);
251 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_current
);
252 misc_deregister(&rng_miscdev
);
255 static int register_miscdev(void)
259 err
= misc_register(&rng_miscdev
);
262 err
= device_create_file(rng_miscdev
.this_device
,
263 &dev_attr_rng_current
);
266 err
= device_create_file(rng_miscdev
.this_device
,
267 &dev_attr_rng_available
);
269 goto err_remove_current
;
274 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_current
);
276 misc_deregister(&rng_miscdev
);
280 int hwrng_register(struct hwrng
*rng
)
282 int must_register_misc
;
284 struct hwrng
*old_rng
, *tmp
;
286 if (rng
->name
== NULL
||
287 rng
->data_read
== NULL
)
290 mutex_lock(&rng_mutex
);
292 /* Must not register two RNGs with the same name. */
294 list_for_each_entry(tmp
, &rng_list
, list
) {
295 if (strcmp(tmp
->name
, rng
->name
) == 0)
299 must_register_misc
= (current_rng
== NULL
);
300 old_rng
= current_rng
;
302 err
= hwrng_init(rng
);
308 if (must_register_misc
) {
309 err
= register_miscdev();
318 INIT_LIST_HEAD(&rng
->list
);
319 list_add_tail(&rng
->list
, &rng_list
);
321 mutex_unlock(&rng_mutex
);
325 EXPORT_SYMBOL_GPL(hwrng_register
);
327 void hwrng_unregister(struct hwrng
*rng
)
331 mutex_lock(&rng_mutex
);
333 list_del(&rng
->list
);
334 if (current_rng
== rng
) {
336 if (list_empty(&rng_list
)) {
339 current_rng
= list_entry(rng_list
.prev
, struct hwrng
, list
);
340 err
= hwrng_init(current_rng
);
345 if (list_empty(&rng_list
))
346 unregister_miscdev();
348 mutex_unlock(&rng_mutex
);
350 EXPORT_SYMBOL_GPL(hwrng_unregister
);
353 MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
354 MODULE_LICENSE("GPL");