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, | |
173 | }; | |
174 | ||
175 | static struct miscdevice rng_miscdev = { | |
176 | .minor = RNG_MISCDEV_MINOR, | |
177 | .name = RNG_MODULE_NAME, | |
e454cea2 | 178 | .nodename = "hwrng", |
844dd05f MB |
179 | .fops = &rng_chrdev_ops, |
180 | }; | |
181 | ||
182 | ||
94fbcded GKH |
183 | static ssize_t hwrng_attr_current_store(struct device *dev, |
184 | struct device_attribute *attr, | |
844dd05f MB |
185 | const char *buf, size_t len) |
186 | { | |
187 | int err; | |
188 | struct hwrng *rng; | |
189 | ||
190 | err = mutex_lock_interruptible(&rng_mutex); | |
191 | if (err) | |
192 | return -ERESTARTSYS; | |
193 | err = -ENODEV; | |
194 | list_for_each_entry(rng, &rng_list, list) { | |
195 | if (strcmp(rng->name, buf) == 0) { | |
196 | if (rng == current_rng) { | |
197 | err = 0; | |
198 | break; | |
199 | } | |
200 | err = hwrng_init(rng); | |
201 | if (err) | |
202 | break; | |
203 | hwrng_cleanup(current_rng); | |
204 | current_rng = rng; | |
205 | err = 0; | |
206 | break; | |
207 | } | |
208 | } | |
209 | mutex_unlock(&rng_mutex); | |
210 | ||
211 | return err ? : len; | |
212 | } | |
213 | ||
94fbcded GKH |
214 | static ssize_t hwrng_attr_current_show(struct device *dev, |
215 | struct device_attribute *attr, | |
844dd05f MB |
216 | char *buf) |
217 | { | |
218 | int err; | |
219 | ssize_t ret; | |
220 | const char *name = "none"; | |
221 | ||
222 | err = mutex_lock_interruptible(&rng_mutex); | |
223 | if (err) | |
224 | return -ERESTARTSYS; | |
225 | if (current_rng) | |
226 | name = current_rng->name; | |
227 | ret = snprintf(buf, PAGE_SIZE, "%s\n", name); | |
228 | mutex_unlock(&rng_mutex); | |
229 | ||
230 | return ret; | |
231 | } | |
232 | ||
94fbcded GKH |
233 | static ssize_t hwrng_attr_available_show(struct device *dev, |
234 | struct device_attribute *attr, | |
844dd05f MB |
235 | char *buf) |
236 | { | |
237 | int err; | |
238 | ssize_t ret = 0; | |
239 | struct hwrng *rng; | |
240 | ||
241 | err = mutex_lock_interruptible(&rng_mutex); | |
242 | if (err) | |
243 | return -ERESTARTSYS; | |
244 | buf[0] = '\0'; | |
245 | list_for_each_entry(rng, &rng_list, list) { | |
246 | strncat(buf, rng->name, PAGE_SIZE - ret - 1); | |
247 | ret += strlen(rng->name); | |
248 | strncat(buf, " ", PAGE_SIZE - ret - 1); | |
249 | ret++; | |
250 | } | |
251 | strncat(buf, "\n", PAGE_SIZE - ret - 1); | |
252 | ret++; | |
253 | mutex_unlock(&rng_mutex); | |
254 | ||
255 | return ret; | |
256 | } | |
257 | ||
94fbcded GKH |
258 | static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, |
259 | hwrng_attr_current_show, | |
260 | hwrng_attr_current_store); | |
261 | static DEVICE_ATTR(rng_available, S_IRUGO, | |
262 | hwrng_attr_available_show, | |
263 | NULL); | |
844dd05f MB |
264 | |
265 | ||
b844eba2 | 266 | static void unregister_miscdev(void) |
844dd05f | 267 | { |
94fbcded GKH |
268 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available); |
269 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); | |
b844eba2 | 270 | misc_deregister(&rng_miscdev); |
844dd05f MB |
271 | } |
272 | ||
273 | static int register_miscdev(void) | |
274 | { | |
275 | int err; | |
276 | ||
277 | err = misc_register(&rng_miscdev); | |
278 | if (err) | |
279 | goto out; | |
94fbcded GKH |
280 | err = device_create_file(rng_miscdev.this_device, |
281 | &dev_attr_rng_current); | |
844dd05f MB |
282 | if (err) |
283 | goto err_misc_dereg; | |
94fbcded GKH |
284 | err = device_create_file(rng_miscdev.this_device, |
285 | &dev_attr_rng_available); | |
844dd05f MB |
286 | if (err) |
287 | goto err_remove_current; | |
288 | out: | |
289 | return err; | |
290 | ||
291 | err_remove_current: | |
94fbcded | 292 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); |
844dd05f MB |
293 | err_misc_dereg: |
294 | misc_deregister(&rng_miscdev); | |
295 | goto out; | |
296 | } | |
297 | ||
298 | int hwrng_register(struct hwrng *rng) | |
299 | { | |
300 | int must_register_misc; | |
301 | int err = -EINVAL; | |
302 | struct hwrng *old_rng, *tmp; | |
303 | ||
304 | if (rng->name == NULL || | |
9996508b | 305 | (rng->data_read == NULL && rng->read == NULL)) |
844dd05f MB |
306 | goto out; |
307 | ||
308 | mutex_lock(&rng_mutex); | |
309 | ||
310 | /* Must not register two RNGs with the same name. */ | |
311 | err = -EEXIST; | |
312 | list_for_each_entry(tmp, &rng_list, list) { | |
313 | if (strcmp(tmp->name, rng->name) == 0) | |
314 | goto out_unlock; | |
315 | } | |
316 | ||
317 | must_register_misc = (current_rng == NULL); | |
318 | old_rng = current_rng; | |
319 | if (!old_rng) { | |
320 | err = hwrng_init(rng); | |
321 | if (err) | |
322 | goto out_unlock; | |
323 | current_rng = rng; | |
324 | } | |
325 | err = 0; | |
326 | if (must_register_misc) { | |
327 | err = register_miscdev(); | |
328 | if (err) { | |
329 | if (!old_rng) { | |
330 | hwrng_cleanup(rng); | |
331 | current_rng = NULL; | |
332 | } | |
333 | goto out_unlock; | |
334 | } | |
335 | } | |
336 | INIT_LIST_HEAD(&rng->list); | |
337 | list_add_tail(&rng->list, &rng_list); | |
338 | out_unlock: | |
339 | mutex_unlock(&rng_mutex); | |
340 | out: | |
341 | return err; | |
342 | } | |
343 | EXPORT_SYMBOL_GPL(hwrng_register); | |
344 | ||
b844eba2 | 345 | void hwrng_unregister(struct hwrng *rng) |
844dd05f MB |
346 | { |
347 | int err; | |
348 | ||
349 | mutex_lock(&rng_mutex); | |
350 | ||
351 | list_del(&rng->list); | |
352 | if (current_rng == rng) { | |
353 | hwrng_cleanup(rng); | |
354 | if (list_empty(&rng_list)) { | |
355 | current_rng = NULL; | |
356 | } else { | |
357 | current_rng = list_entry(rng_list.prev, struct hwrng, list); | |
358 | err = hwrng_init(current_rng); | |
359 | if (err) | |
360 | current_rng = NULL; | |
361 | } | |
362 | } | |
363 | if (list_empty(&rng_list)) | |
b844eba2 | 364 | unregister_miscdev(); |
844dd05f MB |
365 | |
366 | mutex_unlock(&rng_mutex); | |
367 | } | |
b844eba2 | 368 | EXPORT_SYMBOL_GPL(hwrng_unregister); |
844dd05f MB |
369 | |
370 | ||
371 | MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); | |
372 | MODULE_LICENSE("GPL"); |