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 <mbuesch@freenet.de>
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/smp_lock.h>
41 #include <linux/init.h>
42 #include <linux/miscdevice.h>
43 #include <linux/delay.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[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES]
59 static inline int hwrng_init(struct hwrng *rng)
63 return rng->init(rng);
66 static inline void hwrng_cleanup(struct hwrng *rng)
68 if (rng && rng->cleanup)
72 static int rng_dev_open(struct inode *inode, struct file *filp)
74 /* enforce read-only access to this chrdev */
75 if ((filp->f_mode & FMODE_READ) == 0)
77 if (filp->f_mode & FMODE_WRITE)
82 static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
87 return rng->read(rng, (void *)buffer, size, wait);
89 if (rng->data_present)
90 present = rng->data_present(rng, wait);
95 return rng->data_read(rng, (u32 *)buffer);
100 static ssize_t rng_dev_read(struct file *filp, char __user *buf,
101 size_t size, loff_t *offp)
108 if (mutex_lock_interruptible(&rng_mutex)) {
119 bytes_read = rng_get_data(current_rng, rng_buffer,
121 !(filp->f_flags & O_NONBLOCK));
122 if (bytes_read < 0) {
126 data_avail = bytes_read;
130 if (filp->f_flags & O_NONBLOCK) {
141 if (copy_to_user(buf + ret, rng_buffer + data_avail,
151 mutex_unlock(&rng_mutex);
154 schedule_timeout_interruptible(1);
156 if (signal_pending(current)) {
164 mutex_unlock(&rng_mutex);
169 static const struct file_operations rng_chrdev_ops = {
170 .owner = THIS_MODULE,
171 .open = rng_dev_open,
172 .read = rng_dev_read,
175 static struct miscdevice rng_miscdev = {
176 .minor = RNG_MISCDEV_MINOR,
177 .name = RNG_MODULE_NAME,
179 .fops = &rng_chrdev_ops,
183 static ssize_t hwrng_attr_current_store(struct device *dev,
184 struct device_attribute *attr,
185 const char *buf, size_t len)
190 err = mutex_lock_interruptible(&rng_mutex);
194 list_for_each_entry(rng, &rng_list, list) {
195 if (strcmp(rng->name, buf) == 0) {
196 if (rng == current_rng) {
200 err = hwrng_init(rng);
203 hwrng_cleanup(current_rng);
209 mutex_unlock(&rng_mutex);
214 static ssize_t hwrng_attr_current_show(struct device *dev,
215 struct device_attribute *attr,
220 const char *name = "none";
222 err = mutex_lock_interruptible(&rng_mutex);
226 name = current_rng->name;
227 ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
228 mutex_unlock(&rng_mutex);
233 static ssize_t hwrng_attr_available_show(struct device *dev,
234 struct device_attribute *attr,
241 err = mutex_lock_interruptible(&rng_mutex);
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);
251 strncat(buf, "\n", PAGE_SIZE - ret - 1);
253 mutex_unlock(&rng_mutex);
258 static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
259 hwrng_attr_current_show,
260 hwrng_attr_current_store);
261 static DEVICE_ATTR(rng_available, S_IRUGO,
262 hwrng_attr_available_show,
266 static void unregister_miscdev(void)
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);
273 static int register_miscdev(void)
277 err = misc_register(&rng_miscdev);
280 err = device_create_file(rng_miscdev.this_device,
281 &dev_attr_rng_current);
284 err = device_create_file(rng_miscdev.this_device,
285 &dev_attr_rng_available);
287 goto err_remove_current;
292 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
294 misc_deregister(&rng_miscdev);
298 int hwrng_register(struct hwrng *rng)
300 int must_register_misc;
302 struct hwrng *old_rng, *tmp;
304 if (rng->name == NULL ||
305 (rng->data_read == NULL && rng->read == NULL))
308 mutex_lock(&rng_mutex);
310 /* Must not register two RNGs with the same name. */
312 list_for_each_entry(tmp, &rng_list, list) {
313 if (strcmp(tmp->name, rng->name) == 0)
317 must_register_misc = (current_rng == NULL);
318 old_rng = current_rng;
320 err = hwrng_init(rng);
326 if (must_register_misc) {
327 err = register_miscdev();
336 INIT_LIST_HEAD(&rng->list);
337 list_add_tail(&rng->list, &rng_list);
339 mutex_unlock(&rng_mutex);
343 EXPORT_SYMBOL_GPL(hwrng_register);
345 void hwrng_unregister(struct hwrng *rng)
349 mutex_lock(&rng_mutex);
351 list_del(&rng->list);
352 if (current_rng == rng) {
354 if (list_empty(&rng_list)) {
357 current_rng = list_entry(rng_list.prev, struct hwrng, list);
358 err = hwrng_init(current_rng);
363 if (list_empty(&rng_list))
364 unregister_miscdev();
366 mutex_unlock(&rng_mutex);
368 EXPORT_SYMBOL_GPL(hwrng_unregister);
371 MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
372 MODULE_LICENSE("GPL");