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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> |
844dd05f MB |
40 | #include <linux/init.h> |
41 | #include <linux/miscdevice.h> | |
42 | #include <linux/delay.h> | |
43 | #include <asm/uaccess.h> | |
44 | ||
45 | ||
46 | #define RNG_MODULE_NAME "hw_random" | |
47 | #define PFX RNG_MODULE_NAME ": " | |
48 | #define RNG_MISCDEV_MINOR 183 /* official */ | |
49 | ||
50 | ||
51 | static struct hwrng *current_rng; | |
52 | static LIST_HEAD(rng_list); | |
53 | static DEFINE_MUTEX(rng_mutex); | |
54 | ||
55 | ||
56 | static inline int hwrng_init(struct hwrng *rng) | |
57 | { | |
58 | if (!rng->init) | |
59 | return 0; | |
60 | return rng->init(rng); | |
61 | } | |
62 | ||
63 | static inline void hwrng_cleanup(struct hwrng *rng) | |
64 | { | |
65 | if (rng && rng->cleanup) | |
66 | rng->cleanup(rng); | |
67 | } | |
68 | ||
69 | static inline int hwrng_data_present(struct hwrng *rng) | |
70 | { | |
71 | if (!rng->data_present) | |
72 | return 1; | |
73 | return rng->data_present(rng); | |
74 | } | |
75 | ||
76 | static inline int hwrng_data_read(struct hwrng *rng, u32 *data) | |
77 | { | |
78 | return rng->data_read(rng, data); | |
79 | } | |
80 | ||
81 | ||
82 | static int rng_dev_open(struct inode *inode, struct file *filp) | |
83 | { | |
84 | /* enforce read-only access to this chrdev */ | |
85 | if ((filp->f_mode & FMODE_READ) == 0) | |
86 | return -EINVAL; | |
87 | if (filp->f_mode & FMODE_WRITE) | |
88 | return -EINVAL; | |
89 | return 0; | |
90 | } | |
91 | ||
92 | static ssize_t rng_dev_read(struct file *filp, char __user *buf, | |
93 | size_t size, loff_t *offp) | |
94 | { | |
95 | u32 data; | |
96 | ssize_t ret = 0; | |
97 | int i, err = 0; | |
98 | int data_present; | |
99 | int bytes_read; | |
100 | ||
101 | while (size) { | |
102 | err = -ERESTARTSYS; | |
103 | if (mutex_lock_interruptible(&rng_mutex)) | |
104 | goto out; | |
105 | if (!current_rng) { | |
106 | mutex_unlock(&rng_mutex); | |
107 | err = -ENODEV; | |
108 | goto out; | |
109 | } | |
110 | if (filp->f_flags & O_NONBLOCK) { | |
111 | data_present = hwrng_data_present(current_rng); | |
112 | } else { | |
113 | /* Some RNG require some time between data_reads to gather | |
114 | * new entropy. Poll it. | |
115 | */ | |
116 | for (i = 0; i < 20; i++) { | |
117 | data_present = hwrng_data_present(current_rng); | |
118 | if (data_present) | |
119 | break; | |
120 | udelay(10); | |
121 | } | |
122 | } | |
123 | bytes_read = 0; | |
124 | if (data_present) | |
125 | bytes_read = hwrng_data_read(current_rng, &data); | |
126 | mutex_unlock(&rng_mutex); | |
127 | ||
128 | err = -EAGAIN; | |
129 | if (!bytes_read && (filp->f_flags & O_NONBLOCK)) | |
130 | goto out; | |
131 | ||
132 | err = -EFAULT; | |
133 | while (bytes_read && size) { | |
134 | if (put_user((u8)data, buf++)) | |
135 | goto out; | |
136 | size--; | |
137 | ret++; | |
138 | bytes_read--; | |
139 | data >>= 8; | |
140 | } | |
141 | ||
142 | if (need_resched()) | |
143 | schedule_timeout_interruptible(1); | |
144 | err = -ERESTARTSYS; | |
145 | if (signal_pending(current)) | |
146 | goto out; | |
147 | } | |
148 | out: | |
149 | return ret ? : err; | |
150 | } | |
151 | ||
152 | ||
62322d25 | 153 | static const struct file_operations rng_chrdev_ops = { |
844dd05f MB |
154 | .owner = THIS_MODULE, |
155 | .open = rng_dev_open, | |
156 | .read = rng_dev_read, | |
157 | }; | |
158 | ||
159 | static struct miscdevice rng_miscdev = { | |
160 | .minor = RNG_MISCDEV_MINOR, | |
161 | .name = RNG_MODULE_NAME, | |
162 | .fops = &rng_chrdev_ops, | |
163 | }; | |
164 | ||
165 | ||
94fbcded GKH |
166 | static ssize_t hwrng_attr_current_store(struct device *dev, |
167 | struct device_attribute *attr, | |
844dd05f MB |
168 | const char *buf, size_t len) |
169 | { | |
170 | int err; | |
171 | struct hwrng *rng; | |
172 | ||
173 | err = mutex_lock_interruptible(&rng_mutex); | |
174 | if (err) | |
175 | return -ERESTARTSYS; | |
176 | err = -ENODEV; | |
177 | list_for_each_entry(rng, &rng_list, list) { | |
178 | if (strcmp(rng->name, buf) == 0) { | |
179 | if (rng == current_rng) { | |
180 | err = 0; | |
181 | break; | |
182 | } | |
183 | err = hwrng_init(rng); | |
184 | if (err) | |
185 | break; | |
186 | hwrng_cleanup(current_rng); | |
187 | current_rng = rng; | |
188 | err = 0; | |
189 | break; | |
190 | } | |
191 | } | |
192 | mutex_unlock(&rng_mutex); | |
193 | ||
194 | return err ? : len; | |
195 | } | |
196 | ||
94fbcded GKH |
197 | static ssize_t hwrng_attr_current_show(struct device *dev, |
198 | struct device_attribute *attr, | |
844dd05f MB |
199 | char *buf) |
200 | { | |
201 | int err; | |
202 | ssize_t ret; | |
203 | const char *name = "none"; | |
204 | ||
205 | err = mutex_lock_interruptible(&rng_mutex); | |
206 | if (err) | |
207 | return -ERESTARTSYS; | |
208 | if (current_rng) | |
209 | name = current_rng->name; | |
210 | ret = snprintf(buf, PAGE_SIZE, "%s\n", name); | |
211 | mutex_unlock(&rng_mutex); | |
212 | ||
213 | return ret; | |
214 | } | |
215 | ||
94fbcded GKH |
216 | static ssize_t hwrng_attr_available_show(struct device *dev, |
217 | struct device_attribute *attr, | |
844dd05f MB |
218 | char *buf) |
219 | { | |
220 | int err; | |
221 | ssize_t ret = 0; | |
222 | struct hwrng *rng; | |
223 | ||
224 | err = mutex_lock_interruptible(&rng_mutex); | |
225 | if (err) | |
226 | return -ERESTARTSYS; | |
227 | buf[0] = '\0'; | |
228 | list_for_each_entry(rng, &rng_list, list) { | |
229 | strncat(buf, rng->name, PAGE_SIZE - ret - 1); | |
230 | ret += strlen(rng->name); | |
231 | strncat(buf, " ", PAGE_SIZE - ret - 1); | |
232 | ret++; | |
233 | } | |
234 | strncat(buf, "\n", PAGE_SIZE - ret - 1); | |
235 | ret++; | |
236 | mutex_unlock(&rng_mutex); | |
237 | ||
238 | return ret; | |
239 | } | |
240 | ||
94fbcded GKH |
241 | static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, |
242 | hwrng_attr_current_show, | |
243 | hwrng_attr_current_store); | |
244 | static DEVICE_ATTR(rng_available, S_IRUGO, | |
245 | hwrng_attr_available_show, | |
246 | NULL); | |
844dd05f MB |
247 | |
248 | ||
249 | static void unregister_miscdev(void) | |
250 | { | |
94fbcded GKH |
251 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available); |
252 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); | |
844dd05f MB |
253 | misc_deregister(&rng_miscdev); |
254 | } | |
255 | ||
256 | static int register_miscdev(void) | |
257 | { | |
258 | int err; | |
259 | ||
260 | err = misc_register(&rng_miscdev); | |
261 | if (err) | |
262 | goto out; | |
94fbcded GKH |
263 | err = device_create_file(rng_miscdev.this_device, |
264 | &dev_attr_rng_current); | |
844dd05f MB |
265 | if (err) |
266 | goto err_misc_dereg; | |
94fbcded GKH |
267 | err = device_create_file(rng_miscdev.this_device, |
268 | &dev_attr_rng_available); | |
844dd05f MB |
269 | if (err) |
270 | goto err_remove_current; | |
271 | out: | |
272 | return err; | |
273 | ||
274 | err_remove_current: | |
94fbcded | 275 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); |
844dd05f MB |
276 | err_misc_dereg: |
277 | misc_deregister(&rng_miscdev); | |
278 | goto out; | |
279 | } | |
280 | ||
281 | int hwrng_register(struct hwrng *rng) | |
282 | { | |
283 | int must_register_misc; | |
284 | int err = -EINVAL; | |
285 | struct hwrng *old_rng, *tmp; | |
286 | ||
287 | if (rng->name == NULL || | |
288 | rng->data_read == NULL) | |
289 | goto out; | |
290 | ||
291 | mutex_lock(&rng_mutex); | |
292 | ||
293 | /* Must not register two RNGs with the same name. */ | |
294 | err = -EEXIST; | |
295 | list_for_each_entry(tmp, &rng_list, list) { | |
296 | if (strcmp(tmp->name, rng->name) == 0) | |
297 | goto out_unlock; | |
298 | } | |
299 | ||
300 | must_register_misc = (current_rng == NULL); | |
301 | old_rng = current_rng; | |
302 | if (!old_rng) { | |
303 | err = hwrng_init(rng); | |
304 | if (err) | |
305 | goto out_unlock; | |
306 | current_rng = rng; | |
307 | } | |
308 | err = 0; | |
309 | if (must_register_misc) { | |
310 | err = register_miscdev(); | |
311 | if (err) { | |
312 | if (!old_rng) { | |
313 | hwrng_cleanup(rng); | |
314 | current_rng = NULL; | |
315 | } | |
316 | goto out_unlock; | |
317 | } | |
318 | } | |
319 | INIT_LIST_HEAD(&rng->list); | |
320 | list_add_tail(&rng->list, &rng_list); | |
321 | out_unlock: | |
322 | mutex_unlock(&rng_mutex); | |
323 | out: | |
324 | return err; | |
325 | } | |
326 | EXPORT_SYMBOL_GPL(hwrng_register); | |
327 | ||
328 | void hwrng_unregister(struct hwrng *rng) | |
329 | { | |
330 | int err; | |
331 | ||
332 | mutex_lock(&rng_mutex); | |
333 | ||
334 | list_del(&rng->list); | |
335 | if (current_rng == rng) { | |
336 | hwrng_cleanup(rng); | |
337 | if (list_empty(&rng_list)) { | |
338 | current_rng = NULL; | |
339 | } else { | |
340 | current_rng = list_entry(rng_list.prev, struct hwrng, list); | |
341 | err = hwrng_init(current_rng); | |
342 | if (err) | |
343 | current_rng = NULL; | |
344 | } | |
345 | } | |
346 | if (list_empty(&rng_list)) | |
347 | unregister_miscdev(); | |
348 | ||
349 | mutex_unlock(&rng_mutex); | |
350 | } | |
351 | EXPORT_SYMBOL_GPL(hwrng_unregister); | |
352 | ||
353 | ||
354 | MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); | |
355 | MODULE_LICENSE("GPL"); |