Commit | Line | Data |
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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); | |
9996508b | 55 | static int data_avail; |
eed89d0f IM |
56 | static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES] |
57 | __cacheline_aligned; | |
844dd05f MB |
58 | |
59 | static inline int hwrng_init(struct hwrng *rng) | |
60 | { | |
61 | if (!rng->init) | |
62 | return 0; | |
63 | return rng->init(rng); | |
64 | } | |
65 | ||
66 | static inline void hwrng_cleanup(struct hwrng *rng) | |
67 | { | |
68 | if (rng && rng->cleanup) | |
69 | rng->cleanup(rng); | |
70 | } | |
71 | ||
844dd05f MB |
72 | static int rng_dev_open(struct inode *inode, struct file *filp) |
73 | { | |
74 | /* enforce read-only access to this chrdev */ | |
75 | if ((filp->f_mode & FMODE_READ) == 0) | |
76 | return -EINVAL; | |
77 | if (filp->f_mode & FMODE_WRITE) | |
78 | return -EINVAL; | |
79 | return 0; | |
80 | } | |
81 | ||
9996508b IM |
82 | static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, |
83 | int wait) { | |
84 | int present; | |
85 | ||
86 | if (rng->read) | |
87 | return rng->read(rng, (void *)buffer, size, wait); | |
88 | ||
89 | if (rng->data_present) | |
90 | present = rng->data_present(rng, wait); | |
91 | else | |
92 | present = 1; | |
93 | ||
94 | if (present) | |
95 | return rng->data_read(rng, (u32 *)buffer); | |
96 | ||
97 | return 0; | |
98 | } | |
99 | ||
844dd05f MB |
100 | static ssize_t rng_dev_read(struct file *filp, char __user *buf, |
101 | size_t size, loff_t *offp) | |
102 | { | |
844dd05f | 103 | ssize_t ret = 0; |
984e976f | 104 | int err = 0; |
9996508b | 105 | int bytes_read, len; |
844dd05f MB |
106 | |
107 | while (size) { | |
9996508b IM |
108 | if (mutex_lock_interruptible(&rng_mutex)) { |
109 | err = -ERESTARTSYS; | |
844dd05f | 110 | goto out; |
9996508b IM |
111 | } |
112 | ||
844dd05f | 113 | if (!current_rng) { |
844dd05f | 114 | err = -ENODEV; |
9996508b | 115 | goto out_unlock; |
844dd05f | 116 | } |
984e976f | 117 | |
9996508b IM |
118 | if (!data_avail) { |
119 | bytes_read = rng_get_data(current_rng, rng_buffer, | |
120 | sizeof(rng_buffer), | |
121 | !(filp->f_flags & O_NONBLOCK)); | |
122 | if (bytes_read < 0) { | |
123 | err = bytes_read; | |
124 | goto out_unlock; | |
125 | } | |
126 | data_avail = bytes_read; | |
893f1128 | 127 | } |
844dd05f | 128 | |
9996508b IM |
129 | if (!data_avail) { |
130 | if (filp->f_flags & O_NONBLOCK) { | |
131 | err = -EAGAIN; | |
132 | goto out_unlock; | |
133 | } | |
134 | } else { | |
135 | len = data_avail; | |
136 | if (len > size) | |
137 | len = size; | |
138 | ||
139 | data_avail -= len; | |
140 | ||
141 | if (copy_to_user(buf + ret, rng_buffer + data_avail, | |
142 | len)) { | |
143 | err = -EFAULT; | |
144 | goto out_unlock; | |
145 | } | |
146 | ||
147 | size -= len; | |
148 | ret += len; | |
844dd05f MB |
149 | } |
150 | ||
9996508b IM |
151 | mutex_unlock(&rng_mutex); |
152 | ||
844dd05f MB |
153 | if (need_resched()) |
154 | schedule_timeout_interruptible(1); | |
9996508b IM |
155 | |
156 | if (signal_pending(current)) { | |
157 | err = -ERESTARTSYS; | |
844dd05f | 158 | goto out; |
9996508b | 159 | } |
844dd05f MB |
160 | } |
161 | out: | |
162 | return ret ? : err; | |
f5908267 HX |
163 | out_unlock: |
164 | mutex_unlock(&rng_mutex); | |
165 | goto out; | |
844dd05f MB |
166 | } |
167 | ||
168 | ||
62322d25 | 169 | static const struct file_operations rng_chrdev_ops = { |
844dd05f MB |
170 | .owner = THIS_MODULE, |
171 | .open = rng_dev_open, | |
172 | .read = rng_dev_read, | |
6038f373 | 173 | .llseek = noop_llseek, |
844dd05f MB |
174 | }; |
175 | ||
176 | static struct miscdevice rng_miscdev = { | |
177 | .minor = RNG_MISCDEV_MINOR, | |
178 | .name = RNG_MODULE_NAME, | |
e454cea2 | 179 | .nodename = "hwrng", |
844dd05f MB |
180 | .fops = &rng_chrdev_ops, |
181 | }; | |
182 | ||
183 | ||
94fbcded GKH |
184 | static ssize_t hwrng_attr_current_store(struct device *dev, |
185 | struct device_attribute *attr, | |
844dd05f MB |
186 | const char *buf, size_t len) |
187 | { | |
188 | int err; | |
189 | struct hwrng *rng; | |
190 | ||
191 | err = mutex_lock_interruptible(&rng_mutex); | |
192 | if (err) | |
193 | return -ERESTARTSYS; | |
194 | err = -ENODEV; | |
195 | list_for_each_entry(rng, &rng_list, list) { | |
196 | if (strcmp(rng->name, buf) == 0) { | |
197 | if (rng == current_rng) { | |
198 | err = 0; | |
199 | break; | |
200 | } | |
201 | err = hwrng_init(rng); | |
202 | if (err) | |
203 | break; | |
204 | hwrng_cleanup(current_rng); | |
205 | current_rng = rng; | |
206 | err = 0; | |
207 | break; | |
208 | } | |
209 | } | |
210 | mutex_unlock(&rng_mutex); | |
211 | ||
212 | return err ? : len; | |
213 | } | |
214 | ||
94fbcded GKH |
215 | static ssize_t hwrng_attr_current_show(struct device *dev, |
216 | struct device_attribute *attr, | |
844dd05f MB |
217 | char *buf) |
218 | { | |
219 | int err; | |
220 | ssize_t ret; | |
221 | const char *name = "none"; | |
222 | ||
223 | err = mutex_lock_interruptible(&rng_mutex); | |
224 | if (err) | |
225 | return -ERESTARTSYS; | |
226 | if (current_rng) | |
227 | name = current_rng->name; | |
228 | ret = snprintf(buf, PAGE_SIZE, "%s\n", name); | |
229 | mutex_unlock(&rng_mutex); | |
230 | ||
231 | return ret; | |
232 | } | |
233 | ||
94fbcded GKH |
234 | static ssize_t hwrng_attr_available_show(struct device *dev, |
235 | struct device_attribute *attr, | |
844dd05f MB |
236 | char *buf) |
237 | { | |
238 | int err; | |
239 | ssize_t ret = 0; | |
240 | struct hwrng *rng; | |
241 | ||
242 | err = mutex_lock_interruptible(&rng_mutex); | |
243 | if (err) | |
244 | return -ERESTARTSYS; | |
245 | buf[0] = '\0'; | |
246 | list_for_each_entry(rng, &rng_list, list) { | |
247 | strncat(buf, rng->name, PAGE_SIZE - ret - 1); | |
248 | ret += strlen(rng->name); | |
249 | strncat(buf, " ", PAGE_SIZE - ret - 1); | |
250 | ret++; | |
251 | } | |
252 | strncat(buf, "\n", PAGE_SIZE - ret - 1); | |
253 | ret++; | |
254 | mutex_unlock(&rng_mutex); | |
255 | ||
256 | return ret; | |
257 | } | |
258 | ||
94fbcded GKH |
259 | static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, |
260 | hwrng_attr_current_show, | |
261 | hwrng_attr_current_store); | |
262 | static DEVICE_ATTR(rng_available, S_IRUGO, | |
263 | hwrng_attr_available_show, | |
264 | NULL); | |
844dd05f MB |
265 | |
266 | ||
b844eba2 | 267 | static void unregister_miscdev(void) |
844dd05f | 268 | { |
94fbcded GKH |
269 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available); |
270 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); | |
b844eba2 | 271 | misc_deregister(&rng_miscdev); |
844dd05f MB |
272 | } |
273 | ||
274 | static int register_miscdev(void) | |
275 | { | |
276 | int err; | |
277 | ||
278 | err = misc_register(&rng_miscdev); | |
279 | if (err) | |
280 | goto out; | |
94fbcded GKH |
281 | err = device_create_file(rng_miscdev.this_device, |
282 | &dev_attr_rng_current); | |
844dd05f MB |
283 | if (err) |
284 | goto err_misc_dereg; | |
94fbcded GKH |
285 | err = device_create_file(rng_miscdev.this_device, |
286 | &dev_attr_rng_available); | |
844dd05f MB |
287 | if (err) |
288 | goto err_remove_current; | |
289 | out: | |
290 | return err; | |
291 | ||
292 | err_remove_current: | |
94fbcded | 293 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); |
844dd05f MB |
294 | err_misc_dereg: |
295 | misc_deregister(&rng_miscdev); | |
296 | goto out; | |
297 | } | |
298 | ||
299 | int hwrng_register(struct hwrng *rng) | |
300 | { | |
301 | int must_register_misc; | |
302 | int err = -EINVAL; | |
303 | struct hwrng *old_rng, *tmp; | |
304 | ||
305 | if (rng->name == NULL || | |
9996508b | 306 | (rng->data_read == NULL && rng->read == NULL)) |
844dd05f MB |
307 | goto out; |
308 | ||
309 | mutex_lock(&rng_mutex); | |
310 | ||
311 | /* Must not register two RNGs with the same name. */ | |
312 | err = -EEXIST; | |
313 | list_for_each_entry(tmp, &rng_list, list) { | |
314 | if (strcmp(tmp->name, rng->name) == 0) | |
315 | goto out_unlock; | |
316 | } | |
317 | ||
318 | must_register_misc = (current_rng == NULL); | |
319 | old_rng = current_rng; | |
320 | if (!old_rng) { | |
321 | err = hwrng_init(rng); | |
322 | if (err) | |
323 | goto out_unlock; | |
324 | current_rng = rng; | |
325 | } | |
326 | err = 0; | |
327 | if (must_register_misc) { | |
328 | err = register_miscdev(); | |
329 | if (err) { | |
330 | if (!old_rng) { | |
331 | hwrng_cleanup(rng); | |
332 | current_rng = NULL; | |
333 | } | |
334 | goto out_unlock; | |
335 | } | |
336 | } | |
337 | INIT_LIST_HEAD(&rng->list); | |
338 | list_add_tail(&rng->list, &rng_list); | |
339 | out_unlock: | |
340 | mutex_unlock(&rng_mutex); | |
341 | out: | |
342 | return err; | |
343 | } | |
344 | EXPORT_SYMBOL_GPL(hwrng_register); | |
345 | ||
b844eba2 | 346 | void hwrng_unregister(struct hwrng *rng) |
844dd05f MB |
347 | { |
348 | int err; | |
349 | ||
350 | mutex_lock(&rng_mutex); | |
351 | ||
352 | list_del(&rng->list); | |
353 | if (current_rng == rng) { | |
354 | hwrng_cleanup(rng); | |
355 | if (list_empty(&rng_list)) { | |
356 | current_rng = NULL; | |
357 | } else { | |
358 | current_rng = list_entry(rng_list.prev, struct hwrng, list); | |
359 | err = hwrng_init(current_rng); | |
360 | if (err) | |
361 | current_rng = NULL; | |
362 | } | |
363 | } | |
364 | if (list_empty(&rng_list)) | |
b844eba2 | 365 | unregister_miscdev(); |
844dd05f MB |
366 | |
367 | mutex_unlock(&rng_mutex); | |
368 | } | |
b844eba2 | 369 | EXPORT_SYMBOL_GPL(hwrng_unregister); |
844dd05f MB |
370 | |
371 | ||
372 | MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); | |
373 | MODULE_LICENSE("GPL"); |