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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 | ||
984e976f | 69 | static inline int hwrng_data_present(struct hwrng *rng, int wait) |
844dd05f MB |
70 | { |
71 | if (!rng->data_present) | |
72 | return 1; | |
984e976f | 73 | return rng->data_present(rng, wait); |
844dd05f MB |
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; | |
984e976f | 97 | int err = 0; |
844dd05f MB |
98 | int bytes_read; |
99 | ||
100 | while (size) { | |
101 | err = -ERESTARTSYS; | |
102 | if (mutex_lock_interruptible(&rng_mutex)) | |
103 | goto out; | |
104 | if (!current_rng) { | |
105 | mutex_unlock(&rng_mutex); | |
106 | err = -ENODEV; | |
107 | goto out; | |
108 | } | |
984e976f | 109 | |
844dd05f | 110 | bytes_read = 0; |
984e976f PM |
111 | if (hwrng_data_present(current_rng, |
112 | !(filp->f_flags & O_NONBLOCK))) | |
844dd05f MB |
113 | bytes_read = hwrng_data_read(current_rng, &data); |
114 | mutex_unlock(&rng_mutex); | |
115 | ||
116 | err = -EAGAIN; | |
117 | if (!bytes_read && (filp->f_flags & O_NONBLOCK)) | |
118 | goto out; | |
893f1128 RW |
119 | if (bytes_read < 0) { |
120 | err = bytes_read; | |
121 | goto out; | |
122 | } | |
844dd05f MB |
123 | |
124 | err = -EFAULT; | |
125 | while (bytes_read && size) { | |
126 | if (put_user((u8)data, buf++)) | |
127 | goto out; | |
128 | size--; | |
129 | ret++; | |
130 | bytes_read--; | |
131 | data >>= 8; | |
132 | } | |
133 | ||
134 | if (need_resched()) | |
135 | schedule_timeout_interruptible(1); | |
136 | err = -ERESTARTSYS; | |
137 | if (signal_pending(current)) | |
138 | goto out; | |
139 | } | |
140 | out: | |
141 | return ret ? : err; | |
142 | } | |
143 | ||
144 | ||
62322d25 | 145 | static const struct file_operations rng_chrdev_ops = { |
844dd05f MB |
146 | .owner = THIS_MODULE, |
147 | .open = rng_dev_open, | |
148 | .read = rng_dev_read, | |
149 | }; | |
150 | ||
151 | static struct miscdevice rng_miscdev = { | |
152 | .minor = RNG_MISCDEV_MINOR, | |
153 | .name = RNG_MODULE_NAME, | |
154 | .fops = &rng_chrdev_ops, | |
155 | }; | |
156 | ||
157 | ||
94fbcded GKH |
158 | static ssize_t hwrng_attr_current_store(struct device *dev, |
159 | struct device_attribute *attr, | |
844dd05f MB |
160 | const char *buf, size_t len) |
161 | { | |
162 | int err; | |
163 | struct hwrng *rng; | |
164 | ||
165 | err = mutex_lock_interruptible(&rng_mutex); | |
166 | if (err) | |
167 | return -ERESTARTSYS; | |
168 | err = -ENODEV; | |
169 | list_for_each_entry(rng, &rng_list, list) { | |
170 | if (strcmp(rng->name, buf) == 0) { | |
171 | if (rng == current_rng) { | |
172 | err = 0; | |
173 | break; | |
174 | } | |
175 | err = hwrng_init(rng); | |
176 | if (err) | |
177 | break; | |
178 | hwrng_cleanup(current_rng); | |
179 | current_rng = rng; | |
180 | err = 0; | |
181 | break; | |
182 | } | |
183 | } | |
184 | mutex_unlock(&rng_mutex); | |
185 | ||
186 | return err ? : len; | |
187 | } | |
188 | ||
94fbcded GKH |
189 | static ssize_t hwrng_attr_current_show(struct device *dev, |
190 | struct device_attribute *attr, | |
844dd05f MB |
191 | char *buf) |
192 | { | |
193 | int err; | |
194 | ssize_t ret; | |
195 | const char *name = "none"; | |
196 | ||
197 | err = mutex_lock_interruptible(&rng_mutex); | |
198 | if (err) | |
199 | return -ERESTARTSYS; | |
200 | if (current_rng) | |
201 | name = current_rng->name; | |
202 | ret = snprintf(buf, PAGE_SIZE, "%s\n", name); | |
203 | mutex_unlock(&rng_mutex); | |
204 | ||
205 | return ret; | |
206 | } | |
207 | ||
94fbcded GKH |
208 | static ssize_t hwrng_attr_available_show(struct device *dev, |
209 | struct device_attribute *attr, | |
844dd05f MB |
210 | char *buf) |
211 | { | |
212 | int err; | |
213 | ssize_t ret = 0; | |
214 | struct hwrng *rng; | |
215 | ||
216 | err = mutex_lock_interruptible(&rng_mutex); | |
217 | if (err) | |
218 | return -ERESTARTSYS; | |
219 | buf[0] = '\0'; | |
220 | list_for_each_entry(rng, &rng_list, list) { | |
221 | strncat(buf, rng->name, PAGE_SIZE - ret - 1); | |
222 | ret += strlen(rng->name); | |
223 | strncat(buf, " ", PAGE_SIZE - ret - 1); | |
224 | ret++; | |
225 | } | |
226 | strncat(buf, "\n", PAGE_SIZE - ret - 1); | |
227 | ret++; | |
228 | mutex_unlock(&rng_mutex); | |
229 | ||
230 | return ret; | |
231 | } | |
232 | ||
94fbcded GKH |
233 | static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, |
234 | hwrng_attr_current_show, | |
235 | hwrng_attr_current_store); | |
236 | static DEVICE_ATTR(rng_available, S_IRUGO, | |
237 | hwrng_attr_available_show, | |
238 | NULL); | |
844dd05f MB |
239 | |
240 | ||
a41e3dc4 | 241 | static void unregister_miscdev(bool suspended) |
844dd05f | 242 | { |
94fbcded GKH |
243 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available); |
244 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); | |
a41e3dc4 | 245 | __misc_deregister(&rng_miscdev, suspended); |
844dd05f MB |
246 | } |
247 | ||
248 | static int register_miscdev(void) | |
249 | { | |
250 | int err; | |
251 | ||
252 | err = misc_register(&rng_miscdev); | |
253 | if (err) | |
254 | goto out; | |
94fbcded GKH |
255 | err = device_create_file(rng_miscdev.this_device, |
256 | &dev_attr_rng_current); | |
844dd05f MB |
257 | if (err) |
258 | goto err_misc_dereg; | |
94fbcded GKH |
259 | err = device_create_file(rng_miscdev.this_device, |
260 | &dev_attr_rng_available); | |
844dd05f MB |
261 | if (err) |
262 | goto err_remove_current; | |
263 | out: | |
264 | return err; | |
265 | ||
266 | err_remove_current: | |
94fbcded | 267 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); |
844dd05f MB |
268 | err_misc_dereg: |
269 | misc_deregister(&rng_miscdev); | |
270 | goto out; | |
271 | } | |
272 | ||
273 | int hwrng_register(struct hwrng *rng) | |
274 | { | |
275 | int must_register_misc; | |
276 | int err = -EINVAL; | |
277 | struct hwrng *old_rng, *tmp; | |
278 | ||
279 | if (rng->name == NULL || | |
280 | rng->data_read == NULL) | |
281 | goto out; | |
282 | ||
283 | mutex_lock(&rng_mutex); | |
284 | ||
285 | /* Must not register two RNGs with the same name. */ | |
286 | err = -EEXIST; | |
287 | list_for_each_entry(tmp, &rng_list, list) { | |
288 | if (strcmp(tmp->name, rng->name) == 0) | |
289 | goto out_unlock; | |
290 | } | |
291 | ||
292 | must_register_misc = (current_rng == NULL); | |
293 | old_rng = current_rng; | |
294 | if (!old_rng) { | |
295 | err = hwrng_init(rng); | |
296 | if (err) | |
297 | goto out_unlock; | |
298 | current_rng = rng; | |
299 | } | |
300 | err = 0; | |
301 | if (must_register_misc) { | |
302 | err = register_miscdev(); | |
303 | if (err) { | |
304 | if (!old_rng) { | |
305 | hwrng_cleanup(rng); | |
306 | current_rng = NULL; | |
307 | } | |
308 | goto out_unlock; | |
309 | } | |
310 | } | |
311 | INIT_LIST_HEAD(&rng->list); | |
312 | list_add_tail(&rng->list, &rng_list); | |
313 | out_unlock: | |
314 | mutex_unlock(&rng_mutex); | |
315 | out: | |
316 | return err; | |
317 | } | |
318 | EXPORT_SYMBOL_GPL(hwrng_register); | |
319 | ||
a41e3dc4 | 320 | void __hwrng_unregister(struct hwrng *rng, bool suspended) |
844dd05f MB |
321 | { |
322 | int err; | |
323 | ||
324 | mutex_lock(&rng_mutex); | |
325 | ||
326 | list_del(&rng->list); | |
327 | if (current_rng == rng) { | |
328 | hwrng_cleanup(rng); | |
329 | if (list_empty(&rng_list)) { | |
330 | current_rng = NULL; | |
331 | } else { | |
332 | current_rng = list_entry(rng_list.prev, struct hwrng, list); | |
333 | err = hwrng_init(current_rng); | |
334 | if (err) | |
335 | current_rng = NULL; | |
336 | } | |
337 | } | |
338 | if (list_empty(&rng_list)) | |
a41e3dc4 | 339 | unregister_miscdev(suspended); |
844dd05f MB |
340 | |
341 | mutex_unlock(&rng_mutex); | |
342 | } | |
a41e3dc4 | 343 | EXPORT_SYMBOL_GPL(__hwrng_unregister); |
844dd05f MB |
344 | |
345 | ||
346 | MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); | |
347 | MODULE_LICENSE("GPL"); |