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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 <m@bues.ch>
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>
39#include <linux/sched.h>
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
51static struct hwrng *current_rng;
52static LIST_HEAD(rng_list);
53static DEFINE_MUTEX(rng_mutex);
54static int data_avail;
55static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES]
56 __cacheline_aligned;
57
58static inline int hwrng_init(struct hwrng *rng)
59{
60 if (!rng->init)
61 return 0;
62 return rng->init(rng);
63}
64
65static inline void hwrng_cleanup(struct hwrng *rng)
66{
67 if (rng && rng->cleanup)
68 rng->cleanup(rng);
69}
70
71static int rng_dev_open(struct inode *inode, struct file *filp)
72{
73 /* enforce read-only access to this chrdev */
74 if ((filp->f_mode & FMODE_READ) == 0)
75 return -EINVAL;
76 if (filp->f_mode & FMODE_WRITE)
77 return -EINVAL;
78 return 0;
79}
80
81static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
82 int wait) {
83 int present;
84
85 if (rng->read)
86 return rng->read(rng, (void *)buffer, size, wait);
87
88 if (rng->data_present)
89 present = rng->data_present(rng, wait);
90 else
91 present = 1;
92
93 if (present)
94 return rng->data_read(rng, (u32 *)buffer);
95
96 return 0;
97}
98
99static ssize_t rng_dev_read(struct file *filp, char __user *buf,
100 size_t size, loff_t *offp)
101{
102 ssize_t ret = 0;
103 int err = 0;
104 int bytes_read, len;
105
106 while (size) {
107 if (mutex_lock_interruptible(&rng_mutex)) {
108 err = -ERESTARTSYS;
109 goto out;
110 }
111
112 if (!current_rng) {
113 err = -ENODEV;
114 goto out_unlock;
115 }
116
117 if (!data_avail) {
118 bytes_read = rng_get_data(current_rng, rng_buffer,
119 sizeof(rng_buffer),
120 !(filp->f_flags & O_NONBLOCK));
121 if (bytes_read < 0) {
122 err = bytes_read;
123 goto out_unlock;
124 }
125 data_avail = bytes_read;
126 }
127
128 if (!data_avail) {
129 if (filp->f_flags & O_NONBLOCK) {
130 err = -EAGAIN;
131 goto out_unlock;
132 }
133 } else {
134 len = data_avail;
135 if (len > size)
136 len = size;
137
138 data_avail -= len;
139
140 if (copy_to_user(buf + ret, rng_buffer + data_avail,
141 len)) {
142 err = -EFAULT;
143 goto out_unlock;
144 }
145
146 size -= len;
147 ret += len;
148 }
149
150 mutex_unlock(&rng_mutex);
151
152 if (need_resched())
153 schedule_timeout_interruptible(1);
154
155 if (signal_pending(current)) {
156 err = -ERESTARTSYS;
157 goto out;
158 }
159 }
160out:
161 return ret ? : err;
162out_unlock:
163 mutex_unlock(&rng_mutex);
164 goto out;
165}
166
167
168static const struct file_operations rng_chrdev_ops = {
169 .owner = THIS_MODULE,
170 .open = rng_dev_open,
171 .read = rng_dev_read,
172 .llseek = noop_llseek,
173};
174
175static struct miscdevice rng_miscdev = {
176 .minor = RNG_MISCDEV_MINOR,
177 .name = RNG_MODULE_NAME,
178 .nodename = "hwrng",
179 .fops = &rng_chrdev_ops,
180};
181
182
183static ssize_t hwrng_attr_current_store(struct device *dev,
184 struct device_attribute *attr,
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
214static ssize_t hwrng_attr_current_show(struct device *dev,
215 struct device_attribute *attr,
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
233static ssize_t hwrng_attr_available_show(struct device *dev,
234 struct device_attribute *attr,
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
258static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
259 hwrng_attr_current_show,
260 hwrng_attr_current_store);
261static DEVICE_ATTR(rng_available, S_IRUGO,
262 hwrng_attr_available_show,
263 NULL);
264
265
266static void unregister_miscdev(void)
267{
268 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
269 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
270 misc_deregister(&rng_miscdev);
271}
272
273static int register_miscdev(void)
274{
275 int err;
276
277 err = misc_register(&rng_miscdev);
278 if (err)
279 goto out;
280 err = device_create_file(rng_miscdev.this_device,
281 &dev_attr_rng_current);
282 if (err)
283 goto err_misc_dereg;
284 err = device_create_file(rng_miscdev.this_device,
285 &dev_attr_rng_available);
286 if (err)
287 goto err_remove_current;
288out:
289 return err;
290
291err_remove_current:
292 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
293err_misc_dereg:
294 misc_deregister(&rng_miscdev);
295 goto out;
296}
297
298int 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 ||
305 (rng->data_read == NULL && rng->read == NULL))
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);
338out_unlock:
339 mutex_unlock(&rng_mutex);
340out:
341 return err;
342}
343EXPORT_SYMBOL_GPL(hwrng_register);
344
345void hwrng_unregister(struct hwrng *rng)
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))
364 unregister_miscdev();
365
366 mutex_unlock(&rng_mutex);
367}
368EXPORT_SYMBOL_GPL(hwrng_unregister);
369
370
371MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
372MODULE_LICENSE("GPL");
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 <m@bues.ch>
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>
39#include <linux/sched.h>
40#include <linux/miscdevice.h>
41#include <linux/kthread.h>
42#include <linux/delay.h>
43#include <linux/slab.h>
44#include <linux/random.h>
45#include <linux/err.h>
46#include <asm/uaccess.h>
47
48
49#define RNG_MODULE_NAME "hw_random"
50#define PFX RNG_MODULE_NAME ": "
51#define RNG_MISCDEV_MINOR 183 /* official */
52
53
54static struct hwrng *current_rng;
55static struct task_struct *hwrng_fill;
56static LIST_HEAD(rng_list);
57/* Protects rng_list and current_rng */
58static DEFINE_MUTEX(rng_mutex);
59/* Protects rng read functions, data_avail, rng_buffer and rng_fillbuf */
60static DEFINE_MUTEX(reading_mutex);
61static int data_avail;
62static u8 *rng_buffer, *rng_fillbuf;
63static unsigned short current_quality;
64static unsigned short default_quality; /* = 0; default to "off" */
65
66module_param(current_quality, ushort, 0644);
67MODULE_PARM_DESC(current_quality,
68 "current hwrng entropy estimation per mill");
69module_param(default_quality, ushort, 0644);
70MODULE_PARM_DESC(default_quality,
71 "default entropy content of hwrng per mill");
72
73static void drop_current_rng(void);
74static int hwrng_init(struct hwrng *rng);
75static void start_khwrngd(void);
76
77static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
78 int wait);
79
80static size_t rng_buffer_size(void)
81{
82 return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;
83}
84
85static void add_early_randomness(struct hwrng *rng)
86{
87 unsigned char bytes[16];
88 int bytes_read;
89
90 mutex_lock(&reading_mutex);
91 bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
92 mutex_unlock(&reading_mutex);
93 if (bytes_read > 0)
94 add_device_randomness(bytes, bytes_read);
95}
96
97static inline void cleanup_rng(struct kref *kref)
98{
99 struct hwrng *rng = container_of(kref, struct hwrng, ref);
100
101 if (rng->cleanup)
102 rng->cleanup(rng);
103
104 complete(&rng->cleanup_done);
105}
106
107static int set_current_rng(struct hwrng *rng)
108{
109 int err;
110
111 BUG_ON(!mutex_is_locked(&rng_mutex));
112
113 err = hwrng_init(rng);
114 if (err)
115 return err;
116
117 drop_current_rng();
118 current_rng = rng;
119
120 return 0;
121}
122
123static void drop_current_rng(void)
124{
125 BUG_ON(!mutex_is_locked(&rng_mutex));
126 if (!current_rng)
127 return;
128
129 /* decrease last reference for triggering the cleanup */
130 kref_put(¤t_rng->ref, cleanup_rng);
131 current_rng = NULL;
132}
133
134/* Returns ERR_PTR(), NULL or refcounted hwrng */
135static struct hwrng *get_current_rng(void)
136{
137 struct hwrng *rng;
138
139 if (mutex_lock_interruptible(&rng_mutex))
140 return ERR_PTR(-ERESTARTSYS);
141
142 rng = current_rng;
143 if (rng)
144 kref_get(&rng->ref);
145
146 mutex_unlock(&rng_mutex);
147 return rng;
148}
149
150static void put_rng(struct hwrng *rng)
151{
152 /*
153 * Hold rng_mutex here so we serialize in case they set_current_rng
154 * on rng again immediately.
155 */
156 mutex_lock(&rng_mutex);
157 if (rng)
158 kref_put(&rng->ref, cleanup_rng);
159 mutex_unlock(&rng_mutex);
160}
161
162static int hwrng_init(struct hwrng *rng)
163{
164 if (kref_get_unless_zero(&rng->ref))
165 goto skip_init;
166
167 if (rng->init) {
168 int ret;
169
170 ret = rng->init(rng);
171 if (ret)
172 return ret;
173 }
174
175 kref_init(&rng->ref);
176 reinit_completion(&rng->cleanup_done);
177
178skip_init:
179 add_early_randomness(rng);
180
181 current_quality = rng->quality ? : default_quality;
182 if (current_quality > 1024)
183 current_quality = 1024;
184
185 if (current_quality == 0 && hwrng_fill)
186 kthread_stop(hwrng_fill);
187 if (current_quality > 0 && !hwrng_fill)
188 start_khwrngd();
189
190 return 0;
191}
192
193static int rng_dev_open(struct inode *inode, struct file *filp)
194{
195 /* enforce read-only access to this chrdev */
196 if ((filp->f_mode & FMODE_READ) == 0)
197 return -EINVAL;
198 if (filp->f_mode & FMODE_WRITE)
199 return -EINVAL;
200 return 0;
201}
202
203static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
204 int wait) {
205 int present;
206
207 BUG_ON(!mutex_is_locked(&reading_mutex));
208 if (rng->read)
209 return rng->read(rng, (void *)buffer, size, wait);
210
211 if (rng->data_present)
212 present = rng->data_present(rng, wait);
213 else
214 present = 1;
215
216 if (present)
217 return rng->data_read(rng, (u32 *)buffer);
218
219 return 0;
220}
221
222static ssize_t rng_dev_read(struct file *filp, char __user *buf,
223 size_t size, loff_t *offp)
224{
225 ssize_t ret = 0;
226 int err = 0;
227 int bytes_read, len;
228 struct hwrng *rng;
229
230 while (size) {
231 rng = get_current_rng();
232 if (IS_ERR(rng)) {
233 err = PTR_ERR(rng);
234 goto out;
235 }
236 if (!rng) {
237 err = -ENODEV;
238 goto out;
239 }
240
241 if (mutex_lock_interruptible(&reading_mutex)) {
242 err = -ERESTARTSYS;
243 goto out_put;
244 }
245 if (!data_avail) {
246 bytes_read = rng_get_data(rng, rng_buffer,
247 rng_buffer_size(),
248 !(filp->f_flags & O_NONBLOCK));
249 if (bytes_read < 0) {
250 err = bytes_read;
251 goto out_unlock_reading;
252 }
253 data_avail = bytes_read;
254 }
255
256 if (!data_avail) {
257 if (filp->f_flags & O_NONBLOCK) {
258 err = -EAGAIN;
259 goto out_unlock_reading;
260 }
261 } else {
262 len = data_avail;
263 if (len > size)
264 len = size;
265
266 data_avail -= len;
267
268 if (copy_to_user(buf + ret, rng_buffer + data_avail,
269 len)) {
270 err = -EFAULT;
271 goto out_unlock_reading;
272 }
273
274 size -= len;
275 ret += len;
276 }
277
278 mutex_unlock(&reading_mutex);
279 put_rng(rng);
280
281 if (need_resched())
282 schedule_timeout_interruptible(1);
283
284 if (signal_pending(current)) {
285 err = -ERESTARTSYS;
286 goto out;
287 }
288 }
289out:
290 return ret ? : err;
291
292out_unlock_reading:
293 mutex_unlock(&reading_mutex);
294out_put:
295 put_rng(rng);
296 goto out;
297}
298
299
300static const struct file_operations rng_chrdev_ops = {
301 .owner = THIS_MODULE,
302 .open = rng_dev_open,
303 .read = rng_dev_read,
304 .llseek = noop_llseek,
305};
306
307static const struct attribute_group *rng_dev_groups[];
308
309static struct miscdevice rng_miscdev = {
310 .minor = RNG_MISCDEV_MINOR,
311 .name = RNG_MODULE_NAME,
312 .nodename = "hwrng",
313 .fops = &rng_chrdev_ops,
314 .groups = rng_dev_groups,
315};
316
317
318static ssize_t hwrng_attr_current_store(struct device *dev,
319 struct device_attribute *attr,
320 const char *buf, size_t len)
321{
322 int err;
323 struct hwrng *rng;
324
325 err = mutex_lock_interruptible(&rng_mutex);
326 if (err)
327 return -ERESTARTSYS;
328 err = -ENODEV;
329 list_for_each_entry(rng, &rng_list, list) {
330 if (sysfs_streq(rng->name, buf)) {
331 err = 0;
332 if (rng != current_rng)
333 err = set_current_rng(rng);
334 break;
335 }
336 }
337 mutex_unlock(&rng_mutex);
338
339 return err ? : len;
340}
341
342static ssize_t hwrng_attr_current_show(struct device *dev,
343 struct device_attribute *attr,
344 char *buf)
345{
346 ssize_t ret;
347 struct hwrng *rng;
348
349 rng = get_current_rng();
350 if (IS_ERR(rng))
351 return PTR_ERR(rng);
352
353 ret = snprintf(buf, PAGE_SIZE, "%s\n", rng ? rng->name : "none");
354 put_rng(rng);
355
356 return ret;
357}
358
359static ssize_t hwrng_attr_available_show(struct device *dev,
360 struct device_attribute *attr,
361 char *buf)
362{
363 int err;
364 struct hwrng *rng;
365
366 err = mutex_lock_interruptible(&rng_mutex);
367 if (err)
368 return -ERESTARTSYS;
369 buf[0] = '\0';
370 list_for_each_entry(rng, &rng_list, list) {
371 strlcat(buf, rng->name, PAGE_SIZE);
372 strlcat(buf, " ", PAGE_SIZE);
373 }
374 strlcat(buf, "\n", PAGE_SIZE);
375 mutex_unlock(&rng_mutex);
376
377 return strlen(buf);
378}
379
380static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
381 hwrng_attr_current_show,
382 hwrng_attr_current_store);
383static DEVICE_ATTR(rng_available, S_IRUGO,
384 hwrng_attr_available_show,
385 NULL);
386
387static struct attribute *rng_dev_attrs[] = {
388 &dev_attr_rng_current.attr,
389 &dev_attr_rng_available.attr,
390 NULL
391};
392
393ATTRIBUTE_GROUPS(rng_dev);
394
395static void __exit unregister_miscdev(void)
396{
397 misc_deregister(&rng_miscdev);
398}
399
400static int __init register_miscdev(void)
401{
402 return misc_register(&rng_miscdev);
403}
404
405static int hwrng_fillfn(void *unused)
406{
407 long rc;
408
409 while (!kthread_should_stop()) {
410 struct hwrng *rng;
411
412 rng = get_current_rng();
413 if (IS_ERR(rng) || !rng)
414 break;
415 mutex_lock(&reading_mutex);
416 rc = rng_get_data(rng, rng_fillbuf,
417 rng_buffer_size(), 1);
418 mutex_unlock(&reading_mutex);
419 put_rng(rng);
420 if (rc <= 0) {
421 pr_warn("hwrng: no data available\n");
422 msleep_interruptible(10000);
423 continue;
424 }
425 /* Outside lock, sure, but y'know: randomness. */
426 add_hwgenerator_randomness((void *)rng_fillbuf, rc,
427 rc * current_quality * 8 >> 10);
428 }
429 hwrng_fill = NULL;
430 return 0;
431}
432
433static void start_khwrngd(void)
434{
435 hwrng_fill = kthread_run(hwrng_fillfn, NULL, "hwrng");
436 if (IS_ERR(hwrng_fill)) {
437 pr_err("hwrng_fill thread creation failed");
438 hwrng_fill = NULL;
439 }
440}
441
442int hwrng_register(struct hwrng *rng)
443{
444 int err = -EINVAL;
445 struct hwrng *old_rng, *tmp;
446
447 if (rng->name == NULL ||
448 (rng->data_read == NULL && rng->read == NULL))
449 goto out;
450
451 mutex_lock(&rng_mutex);
452
453 /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
454 err = -ENOMEM;
455 if (!rng_buffer) {
456 rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);
457 if (!rng_buffer)
458 goto out_unlock;
459 }
460 if (!rng_fillbuf) {
461 rng_fillbuf = kmalloc(rng_buffer_size(), GFP_KERNEL);
462 if (!rng_fillbuf) {
463 kfree(rng_buffer);
464 goto out_unlock;
465 }
466 }
467
468 /* Must not register two RNGs with the same name. */
469 err = -EEXIST;
470 list_for_each_entry(tmp, &rng_list, list) {
471 if (strcmp(tmp->name, rng->name) == 0)
472 goto out_unlock;
473 }
474
475 init_completion(&rng->cleanup_done);
476 complete(&rng->cleanup_done);
477
478 old_rng = current_rng;
479 err = 0;
480 if (!old_rng) {
481 err = set_current_rng(rng);
482 if (err)
483 goto out_unlock;
484 }
485 list_add_tail(&rng->list, &rng_list);
486
487 if (old_rng && !rng->init) {
488 /*
489 * Use a new device's input to add some randomness to
490 * the system. If this rng device isn't going to be
491 * used right away, its init function hasn't been
492 * called yet; so only use the randomness from devices
493 * that don't need an init callback.
494 */
495 add_early_randomness(rng);
496 }
497
498out_unlock:
499 mutex_unlock(&rng_mutex);
500out:
501 return err;
502}
503EXPORT_SYMBOL_GPL(hwrng_register);
504
505void hwrng_unregister(struct hwrng *rng)
506{
507 mutex_lock(&rng_mutex);
508
509 list_del(&rng->list);
510 if (current_rng == rng) {
511 drop_current_rng();
512 if (!list_empty(&rng_list)) {
513 struct hwrng *tail;
514
515 tail = list_entry(rng_list.prev, struct hwrng, list);
516
517 set_current_rng(tail);
518 }
519 }
520
521 if (list_empty(&rng_list)) {
522 mutex_unlock(&rng_mutex);
523 if (hwrng_fill)
524 kthread_stop(hwrng_fill);
525 } else
526 mutex_unlock(&rng_mutex);
527
528 wait_for_completion(&rng->cleanup_done);
529}
530EXPORT_SYMBOL_GPL(hwrng_unregister);
531
532static void devm_hwrng_release(struct device *dev, void *res)
533{
534 hwrng_unregister(*(struct hwrng **)res);
535}
536
537static int devm_hwrng_match(struct device *dev, void *res, void *data)
538{
539 struct hwrng **r = res;
540
541 if (WARN_ON(!r || !*r))
542 return 0;
543
544 return *r == data;
545}
546
547int devm_hwrng_register(struct device *dev, struct hwrng *rng)
548{
549 struct hwrng **ptr;
550 int error;
551
552 ptr = devres_alloc(devm_hwrng_release, sizeof(*ptr), GFP_KERNEL);
553 if (!ptr)
554 return -ENOMEM;
555
556 error = hwrng_register(rng);
557 if (error) {
558 devres_free(ptr);
559 return error;
560 }
561
562 *ptr = rng;
563 devres_add(dev, ptr);
564 return 0;
565}
566EXPORT_SYMBOL_GPL(devm_hwrng_register);
567
568void devm_hwrng_unregister(struct device *dev, struct hwrng *rng)
569{
570 devres_release(dev, devm_hwrng_release, devm_hwrng_match, rng);
571}
572EXPORT_SYMBOL_GPL(devm_hwrng_unregister);
573
574static int __init hwrng_modinit(void)
575{
576 return register_miscdev();
577}
578
579static void __exit hwrng_modexit(void)
580{
581 mutex_lock(&rng_mutex);
582 BUG_ON(current_rng);
583 kfree(rng_buffer);
584 kfree(rng_fillbuf);
585 mutex_unlock(&rng_mutex);
586
587 unregister_miscdev();
588}
589
590module_init(hwrng_modinit);
591module_exit(hwrng_modexit);
592
593MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
594MODULE_LICENSE("GPL");