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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 | |
eb032b98 | 22 | Copyright 2006 Michael Buesch <m@bues.ch> |
844dd05f MB |
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> | |
f7f154f1 | 43 | #include <linux/slab.h> |
844dd05f MB |
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; |
f7f154f1 RR |
56 | static u8 *rng_buffer; |
57 | ||
58 | static size_t rng_buffer_size(void) | |
59 | { | |
60 | return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES; | |
61 | } | |
844dd05f MB |
62 | |
63 | static inline int hwrng_init(struct hwrng *rng) | |
64 | { | |
65 | if (!rng->init) | |
66 | return 0; | |
67 | return rng->init(rng); | |
68 | } | |
69 | ||
70 | static inline void hwrng_cleanup(struct hwrng *rng) | |
71 | { | |
72 | if (rng && rng->cleanup) | |
73 | rng->cleanup(rng); | |
74 | } | |
75 | ||
844dd05f MB |
76 | static int rng_dev_open(struct inode *inode, struct file *filp) |
77 | { | |
78 | /* enforce read-only access to this chrdev */ | |
79 | if ((filp->f_mode & FMODE_READ) == 0) | |
80 | return -EINVAL; | |
81 | if (filp->f_mode & FMODE_WRITE) | |
82 | return -EINVAL; | |
83 | return 0; | |
84 | } | |
85 | ||
9996508b IM |
86 | static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size, |
87 | int wait) { | |
88 | int present; | |
89 | ||
90 | if (rng->read) | |
91 | return rng->read(rng, (void *)buffer, size, wait); | |
92 | ||
93 | if (rng->data_present) | |
94 | present = rng->data_present(rng, wait); | |
95 | else | |
96 | present = 1; | |
97 | ||
98 | if (present) | |
99 | return rng->data_read(rng, (u32 *)buffer); | |
100 | ||
101 | return 0; | |
102 | } | |
103 | ||
844dd05f MB |
104 | static ssize_t rng_dev_read(struct file *filp, char __user *buf, |
105 | size_t size, loff_t *offp) | |
106 | { | |
844dd05f | 107 | ssize_t ret = 0; |
984e976f | 108 | int err = 0; |
9996508b | 109 | int bytes_read, len; |
844dd05f MB |
110 | |
111 | while (size) { | |
9996508b IM |
112 | if (mutex_lock_interruptible(&rng_mutex)) { |
113 | err = -ERESTARTSYS; | |
844dd05f | 114 | goto out; |
9996508b IM |
115 | } |
116 | ||
844dd05f | 117 | if (!current_rng) { |
844dd05f | 118 | err = -ENODEV; |
9996508b | 119 | goto out_unlock; |
844dd05f | 120 | } |
984e976f | 121 | |
9996508b IM |
122 | if (!data_avail) { |
123 | bytes_read = rng_get_data(current_rng, rng_buffer, | |
f7f154f1 | 124 | rng_buffer_size(), |
9996508b IM |
125 | !(filp->f_flags & O_NONBLOCK)); |
126 | if (bytes_read < 0) { | |
127 | err = bytes_read; | |
128 | goto out_unlock; | |
129 | } | |
130 | data_avail = bytes_read; | |
893f1128 | 131 | } |
844dd05f | 132 | |
9996508b IM |
133 | if (!data_avail) { |
134 | if (filp->f_flags & O_NONBLOCK) { | |
135 | err = -EAGAIN; | |
136 | goto out_unlock; | |
137 | } | |
138 | } else { | |
139 | len = data_avail; | |
140 | if (len > size) | |
141 | len = size; | |
142 | ||
143 | data_avail -= len; | |
144 | ||
145 | if (copy_to_user(buf + ret, rng_buffer + data_avail, | |
146 | len)) { | |
147 | err = -EFAULT; | |
148 | goto out_unlock; | |
149 | } | |
150 | ||
151 | size -= len; | |
152 | ret += len; | |
844dd05f MB |
153 | } |
154 | ||
9996508b IM |
155 | mutex_unlock(&rng_mutex); |
156 | ||
844dd05f MB |
157 | if (need_resched()) |
158 | schedule_timeout_interruptible(1); | |
9996508b IM |
159 | |
160 | if (signal_pending(current)) { | |
161 | err = -ERESTARTSYS; | |
844dd05f | 162 | goto out; |
9996508b | 163 | } |
844dd05f MB |
164 | } |
165 | out: | |
166 | return ret ? : err; | |
f5908267 HX |
167 | out_unlock: |
168 | mutex_unlock(&rng_mutex); | |
169 | goto out; | |
844dd05f MB |
170 | } |
171 | ||
172 | ||
62322d25 | 173 | static const struct file_operations rng_chrdev_ops = { |
844dd05f MB |
174 | .owner = THIS_MODULE, |
175 | .open = rng_dev_open, | |
176 | .read = rng_dev_read, | |
6038f373 | 177 | .llseek = noop_llseek, |
844dd05f MB |
178 | }; |
179 | ||
180 | static struct miscdevice rng_miscdev = { | |
181 | .minor = RNG_MISCDEV_MINOR, | |
182 | .name = RNG_MODULE_NAME, | |
e454cea2 | 183 | .nodename = "hwrng", |
844dd05f MB |
184 | .fops = &rng_chrdev_ops, |
185 | }; | |
186 | ||
187 | ||
94fbcded GKH |
188 | static ssize_t hwrng_attr_current_store(struct device *dev, |
189 | struct device_attribute *attr, | |
844dd05f MB |
190 | const char *buf, size_t len) |
191 | { | |
192 | int err; | |
193 | struct hwrng *rng; | |
194 | ||
195 | err = mutex_lock_interruptible(&rng_mutex); | |
196 | if (err) | |
197 | return -ERESTARTSYS; | |
198 | err = -ENODEV; | |
199 | list_for_each_entry(rng, &rng_list, list) { | |
200 | if (strcmp(rng->name, buf) == 0) { | |
201 | if (rng == current_rng) { | |
202 | err = 0; | |
203 | break; | |
204 | } | |
205 | err = hwrng_init(rng); | |
206 | if (err) | |
207 | break; | |
208 | hwrng_cleanup(current_rng); | |
209 | current_rng = rng; | |
210 | err = 0; | |
211 | break; | |
212 | } | |
213 | } | |
214 | mutex_unlock(&rng_mutex); | |
215 | ||
216 | return err ? : len; | |
217 | } | |
218 | ||
94fbcded GKH |
219 | static ssize_t hwrng_attr_current_show(struct device *dev, |
220 | struct device_attribute *attr, | |
844dd05f MB |
221 | char *buf) |
222 | { | |
223 | int err; | |
224 | ssize_t ret; | |
225 | const char *name = "none"; | |
226 | ||
227 | err = mutex_lock_interruptible(&rng_mutex); | |
228 | if (err) | |
229 | return -ERESTARTSYS; | |
230 | if (current_rng) | |
231 | name = current_rng->name; | |
232 | ret = snprintf(buf, PAGE_SIZE, "%s\n", name); | |
233 | mutex_unlock(&rng_mutex); | |
234 | ||
235 | return ret; | |
236 | } | |
237 | ||
94fbcded GKH |
238 | static ssize_t hwrng_attr_available_show(struct device *dev, |
239 | struct device_attribute *attr, | |
844dd05f MB |
240 | char *buf) |
241 | { | |
242 | int err; | |
243 | ssize_t ret = 0; | |
244 | struct hwrng *rng; | |
245 | ||
246 | err = mutex_lock_interruptible(&rng_mutex); | |
247 | if (err) | |
248 | return -ERESTARTSYS; | |
249 | buf[0] = '\0'; | |
250 | list_for_each_entry(rng, &rng_list, list) { | |
251 | strncat(buf, rng->name, PAGE_SIZE - ret - 1); | |
252 | ret += strlen(rng->name); | |
253 | strncat(buf, " ", PAGE_SIZE - ret - 1); | |
254 | ret++; | |
255 | } | |
256 | strncat(buf, "\n", PAGE_SIZE - ret - 1); | |
257 | ret++; | |
258 | mutex_unlock(&rng_mutex); | |
259 | ||
260 | return ret; | |
261 | } | |
262 | ||
94fbcded GKH |
263 | static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, |
264 | hwrng_attr_current_show, | |
265 | hwrng_attr_current_store); | |
266 | static DEVICE_ATTR(rng_available, S_IRUGO, | |
267 | hwrng_attr_available_show, | |
268 | NULL); | |
844dd05f MB |
269 | |
270 | ||
b844eba2 | 271 | static void unregister_miscdev(void) |
844dd05f | 272 | { |
94fbcded GKH |
273 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available); |
274 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); | |
b844eba2 | 275 | misc_deregister(&rng_miscdev); |
844dd05f MB |
276 | } |
277 | ||
278 | static int register_miscdev(void) | |
279 | { | |
280 | int err; | |
281 | ||
282 | err = misc_register(&rng_miscdev); | |
283 | if (err) | |
284 | goto out; | |
94fbcded GKH |
285 | err = device_create_file(rng_miscdev.this_device, |
286 | &dev_attr_rng_current); | |
844dd05f MB |
287 | if (err) |
288 | goto err_misc_dereg; | |
94fbcded GKH |
289 | err = device_create_file(rng_miscdev.this_device, |
290 | &dev_attr_rng_available); | |
844dd05f MB |
291 | if (err) |
292 | goto err_remove_current; | |
293 | out: | |
294 | return err; | |
295 | ||
296 | err_remove_current: | |
94fbcded | 297 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); |
844dd05f MB |
298 | err_misc_dereg: |
299 | misc_deregister(&rng_miscdev); | |
300 | goto out; | |
301 | } | |
302 | ||
303 | int hwrng_register(struct hwrng *rng) | |
304 | { | |
305 | int must_register_misc; | |
306 | int err = -EINVAL; | |
307 | struct hwrng *old_rng, *tmp; | |
308 | ||
309 | if (rng->name == NULL || | |
9996508b | 310 | (rng->data_read == NULL && rng->read == NULL)) |
844dd05f MB |
311 | goto out; |
312 | ||
313 | mutex_lock(&rng_mutex); | |
314 | ||
f7f154f1 RR |
315 | /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */ |
316 | err = -ENOMEM; | |
317 | if (!rng_buffer) { | |
318 | rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL); | |
319 | if (!rng_buffer) | |
320 | goto out_unlock; | |
321 | } | |
322 | ||
844dd05f MB |
323 | /* Must not register two RNGs with the same name. */ |
324 | err = -EEXIST; | |
325 | list_for_each_entry(tmp, &rng_list, list) { | |
326 | if (strcmp(tmp->name, rng->name) == 0) | |
327 | goto out_unlock; | |
328 | } | |
329 | ||
330 | must_register_misc = (current_rng == NULL); | |
331 | old_rng = current_rng; | |
332 | if (!old_rng) { | |
333 | err = hwrng_init(rng); | |
334 | if (err) | |
335 | goto out_unlock; | |
336 | current_rng = rng; | |
337 | } | |
338 | err = 0; | |
339 | if (must_register_misc) { | |
340 | err = register_miscdev(); | |
341 | if (err) { | |
342 | if (!old_rng) { | |
343 | hwrng_cleanup(rng); | |
344 | current_rng = NULL; | |
345 | } | |
346 | goto out_unlock; | |
347 | } | |
348 | } | |
349 | INIT_LIST_HEAD(&rng->list); | |
350 | list_add_tail(&rng->list, &rng_list); | |
351 | out_unlock: | |
352 | mutex_unlock(&rng_mutex); | |
353 | out: | |
354 | return err; | |
355 | } | |
356 | EXPORT_SYMBOL_GPL(hwrng_register); | |
357 | ||
b844eba2 | 358 | void hwrng_unregister(struct hwrng *rng) |
844dd05f MB |
359 | { |
360 | int err; | |
361 | ||
362 | mutex_lock(&rng_mutex); | |
363 | ||
364 | list_del(&rng->list); | |
365 | if (current_rng == rng) { | |
366 | hwrng_cleanup(rng); | |
367 | if (list_empty(&rng_list)) { | |
368 | current_rng = NULL; | |
369 | } else { | |
370 | current_rng = list_entry(rng_list.prev, struct hwrng, list); | |
371 | err = hwrng_init(current_rng); | |
372 | if (err) | |
373 | current_rng = NULL; | |
374 | } | |
375 | } | |
376 | if (list_empty(&rng_list)) | |
b844eba2 | 377 | unregister_miscdev(); |
844dd05f MB |
378 | |
379 | mutex_unlock(&rng_mutex); | |
380 | } | |
b844eba2 | 381 | EXPORT_SYMBOL_GPL(hwrng_unregister); |
844dd05f MB |
382 | |
383 | ||
384 | MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); | |
385 | MODULE_LICENSE("GPL"); |