2 Added support for the AMD Geode LX RNG
3 (c) Copyright 2004-2005 Advanced Micro Devices, Inc.
7 Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
8 (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>
12 Hardware driver for the AMD 768 Random Number Generator (RNG)
13 (c) Copyright 2001 Red Hat Inc <alan@redhat.com>
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>
22 Copyright 2006 Michael Buesch <m@bues.ch>
23 Copyright 2005 (c) MontaVista Software, Inc.
25 Please read Documentation/hw_random.txt for details on use.
27 ----------------------------------------------------------
28 This software may be used and distributed according to the terms
29 of the GNU General Public License, incorporated herein by reference.
34 #include <linux/device.h>
35 #include <linux/hw_random.h>
36 #include <linux/module.h>
37 #include <linux/kernel.h>
39 #include <linux/sched.h>
40 #include <linux/miscdevice.h>
41 #include <linux/delay.h>
42 #include <linux/slab.h>
43 #include <linux/random.h>
44 #include <asm/uaccess.h>
47 #define RNG_MODULE_NAME "hw_random"
48 #define PFX RNG_MODULE_NAME ": "
49 #define RNG_MISCDEV_MINOR 183 /* official */
52 static struct hwrng *current_rng;
53 static LIST_HEAD(rng_list);
54 static DEFINE_MUTEX(rng_mutex);
55 static int data_avail;
56 static u8 *rng_buffer;
58 static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
61 static size_t rng_buffer_size(void)
63 return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;
66 static void add_early_randomness(struct hwrng *rng)
68 unsigned char bytes[16];
72 * Currently only virtio-rng cannot return data during device
73 * probe, and that's handled in virtio-rng.c itself. If there
74 * are more such devices, this call to rng_get_data can be
75 * made conditional here instead of doing it per-device.
77 bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
79 add_device_randomness(bytes, bytes_read);
82 static inline int hwrng_init(struct hwrng *rng)
91 add_early_randomness(rng);
95 static inline void hwrng_cleanup(struct hwrng *rng)
97 if (rng && rng->cleanup)
101 static int rng_dev_open(struct inode *inode, struct file *filp)
103 /* enforce read-only access to this chrdev */
104 if ((filp->f_mode & FMODE_READ) == 0)
106 if (filp->f_mode & FMODE_WRITE)
111 static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
116 return rng->read(rng, (void *)buffer, size, wait);
118 if (rng->data_present)
119 present = rng->data_present(rng, wait);
124 return rng->data_read(rng, (u32 *)buffer);
129 static ssize_t rng_dev_read(struct file *filp, char __user *buf,
130 size_t size, loff_t *offp)
137 if (mutex_lock_interruptible(&rng_mutex)) {
148 bytes_read = rng_get_data(current_rng, rng_buffer,
150 !(filp->f_flags & O_NONBLOCK));
151 if (bytes_read < 0) {
155 data_avail = bytes_read;
159 if (filp->f_flags & O_NONBLOCK) {
170 if (copy_to_user(buf + ret, rng_buffer + data_avail,
180 mutex_unlock(&rng_mutex);
183 schedule_timeout_interruptible(1);
185 if (signal_pending(current)) {
193 mutex_unlock(&rng_mutex);
198 static const struct file_operations rng_chrdev_ops = {
199 .owner = THIS_MODULE,
200 .open = rng_dev_open,
201 .read = rng_dev_read,
202 .llseek = noop_llseek,
205 static struct miscdevice rng_miscdev = {
206 .minor = RNG_MISCDEV_MINOR,
207 .name = RNG_MODULE_NAME,
209 .fops = &rng_chrdev_ops,
213 static ssize_t hwrng_attr_current_store(struct device *dev,
214 struct device_attribute *attr,
215 const char *buf, size_t len)
220 err = mutex_lock_interruptible(&rng_mutex);
224 list_for_each_entry(rng, &rng_list, list) {
225 if (strcmp(rng->name, buf) == 0) {
226 if (rng == current_rng) {
230 err = hwrng_init(rng);
233 hwrng_cleanup(current_rng);
239 mutex_unlock(&rng_mutex);
244 static ssize_t hwrng_attr_current_show(struct device *dev,
245 struct device_attribute *attr,
250 const char *name = "none";
252 err = mutex_lock_interruptible(&rng_mutex);
256 name = current_rng->name;
257 ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
258 mutex_unlock(&rng_mutex);
263 static ssize_t hwrng_attr_available_show(struct device *dev,
264 struct device_attribute *attr,
271 err = mutex_lock_interruptible(&rng_mutex);
275 list_for_each_entry(rng, &rng_list, list) {
276 strncat(buf, rng->name, PAGE_SIZE - ret - 1);
277 ret += strlen(rng->name);
278 strncat(buf, " ", PAGE_SIZE - ret - 1);
281 strncat(buf, "\n", PAGE_SIZE - ret - 1);
283 mutex_unlock(&rng_mutex);
288 static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
289 hwrng_attr_current_show,
290 hwrng_attr_current_store);
291 static DEVICE_ATTR(rng_available, S_IRUGO,
292 hwrng_attr_available_show,
296 static void unregister_miscdev(void)
298 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
299 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
300 misc_deregister(&rng_miscdev);
303 static int register_miscdev(void)
307 err = misc_register(&rng_miscdev);
310 err = device_create_file(rng_miscdev.this_device,
311 &dev_attr_rng_current);
314 err = device_create_file(rng_miscdev.this_device,
315 &dev_attr_rng_available);
317 goto err_remove_current;
322 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
324 misc_deregister(&rng_miscdev);
328 int hwrng_register(struct hwrng *rng)
331 struct hwrng *old_rng, *tmp;
333 if (rng->name == NULL ||
334 (rng->data_read == NULL && rng->read == NULL))
337 mutex_lock(&rng_mutex);
339 /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
342 rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);
347 /* Must not register two RNGs with the same name. */
349 list_for_each_entry(tmp, &rng_list, list) {
350 if (strcmp(tmp->name, rng->name) == 0)
354 old_rng = current_rng;
356 err = hwrng_init(rng);
363 err = register_miscdev();
370 INIT_LIST_HEAD(&rng->list);
371 list_add_tail(&rng->list, &rng_list);
373 if (old_rng && !rng->init) {
375 * Use a new device's input to add some randomness to
376 * the system. If this rng device isn't going to be
377 * used right away, its init function hasn't been
378 * called yet; so only use the randomness from devices
379 * that don't need an init callback.
381 add_early_randomness(rng);
385 mutex_unlock(&rng_mutex);
389 EXPORT_SYMBOL_GPL(hwrng_register);
391 void hwrng_unregister(struct hwrng *rng)
395 mutex_lock(&rng_mutex);
397 list_del(&rng->list);
398 if (current_rng == rng) {
400 if (list_empty(&rng_list)) {
403 current_rng = list_entry(rng_list.prev, struct hwrng, list);
404 err = hwrng_init(current_rng);
409 if (list_empty(&rng_list))
410 unregister_miscdev();
412 mutex_unlock(&rng_mutex);
414 EXPORT_SYMBOL_GPL(hwrng_unregister);
416 static void __exit hwrng_exit(void)
418 mutex_lock(&rng_mutex);
421 mutex_unlock(&rng_mutex);
424 module_exit(hwrng_exit);
426 MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
427 MODULE_LICENSE("GPL");