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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); | |
55 | ||
56 | ||
57 | static inline int hwrng_init(struct hwrng *rng) | |
58 | { | |
59 | if (!rng->init) | |
60 | return 0; | |
61 | return rng->init(rng); | |
62 | } | |
63 | ||
64 | static inline void hwrng_cleanup(struct hwrng *rng) | |
65 | { | |
66 | if (rng && rng->cleanup) | |
67 | rng->cleanup(rng); | |
68 | } | |
69 | ||
984e976f | 70 | static inline int hwrng_data_present(struct hwrng *rng, int wait) |
844dd05f MB |
71 | { |
72 | if (!rng->data_present) | |
73 | return 1; | |
984e976f | 74 | return rng->data_present(rng, wait); |
844dd05f MB |
75 | } |
76 | ||
77 | static inline int hwrng_data_read(struct hwrng *rng, u32 *data) | |
78 | { | |
79 | return rng->data_read(rng, data); | |
80 | } | |
81 | ||
82 | ||
83 | static int rng_dev_open(struct inode *inode, struct file *filp) | |
84 | { | |
85 | /* enforce read-only access to this chrdev */ | |
86 | if ((filp->f_mode & FMODE_READ) == 0) | |
87 | return -EINVAL; | |
88 | if (filp->f_mode & FMODE_WRITE) | |
89 | return -EINVAL; | |
a9c4e8f7 | 90 | cycle_kernel_lock(); |
844dd05f MB |
91 | return 0; |
92 | } | |
93 | ||
94 | static ssize_t rng_dev_read(struct file *filp, char __user *buf, | |
95 | size_t size, loff_t *offp) | |
96 | { | |
97 | u32 data; | |
98 | ssize_t ret = 0; | |
984e976f | 99 | int err = 0; |
844dd05f MB |
100 | int bytes_read; |
101 | ||
102 | while (size) { | |
103 | err = -ERESTARTSYS; | |
104 | if (mutex_lock_interruptible(&rng_mutex)) | |
105 | goto out; | |
106 | if (!current_rng) { | |
107 | mutex_unlock(&rng_mutex); | |
108 | err = -ENODEV; | |
109 | goto out; | |
110 | } | |
984e976f | 111 | |
844dd05f | 112 | bytes_read = 0; |
984e976f PM |
113 | if (hwrng_data_present(current_rng, |
114 | !(filp->f_flags & O_NONBLOCK))) | |
844dd05f MB |
115 | bytes_read = hwrng_data_read(current_rng, &data); |
116 | mutex_unlock(&rng_mutex); | |
117 | ||
118 | err = -EAGAIN; | |
119 | if (!bytes_read && (filp->f_flags & O_NONBLOCK)) | |
120 | goto out; | |
893f1128 RW |
121 | if (bytes_read < 0) { |
122 | err = bytes_read; | |
123 | goto out; | |
124 | } | |
844dd05f MB |
125 | |
126 | err = -EFAULT; | |
127 | while (bytes_read && size) { | |
128 | if (put_user((u8)data, buf++)) | |
129 | goto out; | |
130 | size--; | |
131 | ret++; | |
132 | bytes_read--; | |
133 | data >>= 8; | |
134 | } | |
135 | ||
136 | if (need_resched()) | |
137 | schedule_timeout_interruptible(1); | |
138 | err = -ERESTARTSYS; | |
139 | if (signal_pending(current)) | |
140 | goto out; | |
141 | } | |
142 | out: | |
143 | return ret ? : err; | |
144 | } | |
145 | ||
146 | ||
62322d25 | 147 | static const struct file_operations rng_chrdev_ops = { |
844dd05f MB |
148 | .owner = THIS_MODULE, |
149 | .open = rng_dev_open, | |
150 | .read = rng_dev_read, | |
151 | }; | |
152 | ||
153 | static struct miscdevice rng_miscdev = { | |
154 | .minor = RNG_MISCDEV_MINOR, | |
155 | .name = RNG_MODULE_NAME, | |
d4056405 | 156 | .devnode = "hwrng", |
844dd05f MB |
157 | .fops = &rng_chrdev_ops, |
158 | }; | |
159 | ||
160 | ||
94fbcded GKH |
161 | static ssize_t hwrng_attr_current_store(struct device *dev, |
162 | struct device_attribute *attr, | |
844dd05f MB |
163 | const char *buf, size_t len) |
164 | { | |
165 | int err; | |
166 | struct hwrng *rng; | |
167 | ||
168 | err = mutex_lock_interruptible(&rng_mutex); | |
169 | if (err) | |
170 | return -ERESTARTSYS; | |
171 | err = -ENODEV; | |
172 | list_for_each_entry(rng, &rng_list, list) { | |
173 | if (strcmp(rng->name, buf) == 0) { | |
174 | if (rng == current_rng) { | |
175 | err = 0; | |
176 | break; | |
177 | } | |
178 | err = hwrng_init(rng); | |
179 | if (err) | |
180 | break; | |
181 | hwrng_cleanup(current_rng); | |
182 | current_rng = rng; | |
183 | err = 0; | |
184 | break; | |
185 | } | |
186 | } | |
187 | mutex_unlock(&rng_mutex); | |
188 | ||
189 | return err ? : len; | |
190 | } | |
191 | ||
94fbcded GKH |
192 | static ssize_t hwrng_attr_current_show(struct device *dev, |
193 | struct device_attribute *attr, | |
844dd05f MB |
194 | char *buf) |
195 | { | |
196 | int err; | |
197 | ssize_t ret; | |
198 | const char *name = "none"; | |
199 | ||
200 | err = mutex_lock_interruptible(&rng_mutex); | |
201 | if (err) | |
202 | return -ERESTARTSYS; | |
203 | if (current_rng) | |
204 | name = current_rng->name; | |
205 | ret = snprintf(buf, PAGE_SIZE, "%s\n", name); | |
206 | mutex_unlock(&rng_mutex); | |
207 | ||
208 | return ret; | |
209 | } | |
210 | ||
94fbcded GKH |
211 | static ssize_t hwrng_attr_available_show(struct device *dev, |
212 | struct device_attribute *attr, | |
844dd05f MB |
213 | char *buf) |
214 | { | |
215 | int err; | |
216 | ssize_t ret = 0; | |
217 | struct hwrng *rng; | |
218 | ||
219 | err = mutex_lock_interruptible(&rng_mutex); | |
220 | if (err) | |
221 | return -ERESTARTSYS; | |
222 | buf[0] = '\0'; | |
223 | list_for_each_entry(rng, &rng_list, list) { | |
224 | strncat(buf, rng->name, PAGE_SIZE - ret - 1); | |
225 | ret += strlen(rng->name); | |
226 | strncat(buf, " ", PAGE_SIZE - ret - 1); | |
227 | ret++; | |
228 | } | |
229 | strncat(buf, "\n", PAGE_SIZE - ret - 1); | |
230 | ret++; | |
231 | mutex_unlock(&rng_mutex); | |
232 | ||
233 | return ret; | |
234 | } | |
235 | ||
94fbcded GKH |
236 | static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, |
237 | hwrng_attr_current_show, | |
238 | hwrng_attr_current_store); | |
239 | static DEVICE_ATTR(rng_available, S_IRUGO, | |
240 | hwrng_attr_available_show, | |
241 | NULL); | |
844dd05f MB |
242 | |
243 | ||
b844eba2 | 244 | static void unregister_miscdev(void) |
844dd05f | 245 | { |
94fbcded GKH |
246 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available); |
247 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); | |
b844eba2 | 248 | misc_deregister(&rng_miscdev); |
844dd05f MB |
249 | } |
250 | ||
251 | static int register_miscdev(void) | |
252 | { | |
253 | int err; | |
254 | ||
255 | err = misc_register(&rng_miscdev); | |
256 | if (err) | |
257 | goto out; | |
94fbcded GKH |
258 | err = device_create_file(rng_miscdev.this_device, |
259 | &dev_attr_rng_current); | |
844dd05f MB |
260 | if (err) |
261 | goto err_misc_dereg; | |
94fbcded GKH |
262 | err = device_create_file(rng_miscdev.this_device, |
263 | &dev_attr_rng_available); | |
844dd05f MB |
264 | if (err) |
265 | goto err_remove_current; | |
266 | out: | |
267 | return err; | |
268 | ||
269 | err_remove_current: | |
94fbcded | 270 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); |
844dd05f MB |
271 | err_misc_dereg: |
272 | misc_deregister(&rng_miscdev); | |
273 | goto out; | |
274 | } | |
275 | ||
276 | int hwrng_register(struct hwrng *rng) | |
277 | { | |
278 | int must_register_misc; | |
279 | int err = -EINVAL; | |
280 | struct hwrng *old_rng, *tmp; | |
281 | ||
282 | if (rng->name == NULL || | |
283 | rng->data_read == NULL) | |
284 | goto out; | |
285 | ||
286 | mutex_lock(&rng_mutex); | |
287 | ||
288 | /* Must not register two RNGs with the same name. */ | |
289 | err = -EEXIST; | |
290 | list_for_each_entry(tmp, &rng_list, list) { | |
291 | if (strcmp(tmp->name, rng->name) == 0) | |
292 | goto out_unlock; | |
293 | } | |
294 | ||
295 | must_register_misc = (current_rng == NULL); | |
296 | old_rng = current_rng; | |
297 | if (!old_rng) { | |
298 | err = hwrng_init(rng); | |
299 | if (err) | |
300 | goto out_unlock; | |
301 | current_rng = rng; | |
302 | } | |
303 | err = 0; | |
304 | if (must_register_misc) { | |
305 | err = register_miscdev(); | |
306 | if (err) { | |
307 | if (!old_rng) { | |
308 | hwrng_cleanup(rng); | |
309 | current_rng = NULL; | |
310 | } | |
311 | goto out_unlock; | |
312 | } | |
313 | } | |
314 | INIT_LIST_HEAD(&rng->list); | |
315 | list_add_tail(&rng->list, &rng_list); | |
316 | out_unlock: | |
317 | mutex_unlock(&rng_mutex); | |
318 | out: | |
319 | return err; | |
320 | } | |
321 | EXPORT_SYMBOL_GPL(hwrng_register); | |
322 | ||
b844eba2 | 323 | void hwrng_unregister(struct hwrng *rng) |
844dd05f MB |
324 | { |
325 | int err; | |
326 | ||
327 | mutex_lock(&rng_mutex); | |
328 | ||
329 | list_del(&rng->list); | |
330 | if (current_rng == rng) { | |
331 | hwrng_cleanup(rng); | |
332 | if (list_empty(&rng_list)) { | |
333 | current_rng = NULL; | |
334 | } else { | |
335 | current_rng = list_entry(rng_list.prev, struct hwrng, list); | |
336 | err = hwrng_init(current_rng); | |
337 | if (err) | |
338 | current_rng = NULL; | |
339 | } | |
340 | } | |
341 | if (list_empty(&rng_list)) | |
b844eba2 | 342 | unregister_miscdev(); |
844dd05f MB |
343 | |
344 | mutex_unlock(&rng_mutex); | |
345 | } | |
b844eba2 | 346 | EXPORT_SYMBOL_GPL(hwrng_unregister); |
844dd05f MB |
347 | |
348 | ||
349 | MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); | |
350 | MODULE_LICENSE("GPL"); |