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/init.h>
41 #include <linux/miscdevice.h>
42 #include <linux/delay.h>
43 #include <linux/slab.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 size_t rng_buffer_size(void)
60 return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;
63 static inline int hwrng_init(struct hwrng *rng)
67 return rng->init(rng);
70 static inline void hwrng_cleanup(struct hwrng *rng)
72 if (rng && rng->cleanup)
76 static int rng_dev_open(struct inode *inode, struct file *filp)
78 /* enforce read-only access to this chrdev */
79 if ((filp->f_mode & FMODE_READ) == 0)
81 if (filp->f_mode & FMODE_WRITE)
86 static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
91 return rng->read(rng, (void *)buffer, size, wait);
93 if (rng->data_present)
94 present = rng->data_present(rng, wait);
99 return rng->data_read(rng, (u32 *)buffer);
104 static ssize_t rng_dev_read(struct file *filp, char __user *buf,
105 size_t size, loff_t *offp)
112 if (mutex_lock_interruptible(&rng_mutex)) {
123 bytes_read = rng_get_data(current_rng, rng_buffer,
125 !(filp->f_flags & O_NONBLOCK));
126 if (bytes_read < 0) {
130 data_avail = bytes_read;
134 if (filp->f_flags & O_NONBLOCK) {
145 if (copy_to_user(buf + ret, rng_buffer + data_avail,
155 mutex_unlock(&rng_mutex);
158 schedule_timeout_interruptible(1);
160 if (signal_pending(current)) {
168 mutex_unlock(&rng_mutex);
173 static const struct file_operations rng_chrdev_ops = {
174 .owner = THIS_MODULE,
175 .open = rng_dev_open,
176 .read = rng_dev_read,
177 .llseek = noop_llseek,
180 static struct miscdevice rng_miscdev = {
181 .minor = RNG_MISCDEV_MINOR,
182 .name = RNG_MODULE_NAME,
184 .fops = &rng_chrdev_ops,
188 static ssize_t hwrng_attr_current_store(struct device *dev,
189 struct device_attribute *attr,
190 const char *buf, size_t len)
195 err = mutex_lock_interruptible(&rng_mutex);
199 list_for_each_entry(rng, &rng_list, list) {
200 if (strcmp(rng->name, buf) == 0) {
201 if (rng == current_rng) {
205 err = hwrng_init(rng);
208 hwrng_cleanup(current_rng);
214 mutex_unlock(&rng_mutex);
219 static ssize_t hwrng_attr_current_show(struct device *dev,
220 struct device_attribute *attr,
225 const char *name = "none";
227 err = mutex_lock_interruptible(&rng_mutex);
231 name = current_rng->name;
232 ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
233 mutex_unlock(&rng_mutex);
238 static ssize_t hwrng_attr_available_show(struct device *dev,
239 struct device_attribute *attr,
246 err = mutex_lock_interruptible(&rng_mutex);
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);
256 strncat(buf, "\n", PAGE_SIZE - ret - 1);
258 mutex_unlock(&rng_mutex);
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,
271 static void unregister_miscdev(void)
273 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
274 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
275 misc_deregister(&rng_miscdev);
278 static int register_miscdev(void)
282 err = misc_register(&rng_miscdev);
285 err = device_create_file(rng_miscdev.this_device,
286 &dev_attr_rng_current);
289 err = device_create_file(rng_miscdev.this_device,
290 &dev_attr_rng_available);
292 goto err_remove_current;
297 device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
299 misc_deregister(&rng_miscdev);
303 int hwrng_register(struct hwrng *rng)
305 int must_register_misc;
307 struct hwrng *old_rng, *tmp;
309 if (rng->name == NULL ||
310 (rng->data_read == NULL && rng->read == NULL))
313 mutex_lock(&rng_mutex);
315 /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
318 rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);
323 /* Must not register two RNGs with the same name. */
325 list_for_each_entry(tmp, &rng_list, list) {
326 if (strcmp(tmp->name, rng->name) == 0)
330 must_register_misc = (current_rng == NULL);
331 old_rng = current_rng;
333 err = hwrng_init(rng);
339 if (must_register_misc) {
340 err = register_miscdev();
349 INIT_LIST_HEAD(&rng->list);
350 list_add_tail(&rng->list, &rng_list);
352 mutex_unlock(&rng_mutex);
356 EXPORT_SYMBOL_GPL(hwrng_register);
358 void hwrng_unregister(struct hwrng *rng)
362 mutex_lock(&rng_mutex);
364 list_del(&rng->list);
365 if (current_rng == rng) {
367 if (list_empty(&rng_list)) {
370 current_rng = list_entry(rng_list.prev, struct hwrng, list);
371 err = hwrng_init(current_rng);
376 if (list_empty(&rng_list))
377 unregister_miscdev();
379 mutex_unlock(&rng_mutex);
381 EXPORT_SYMBOL_GPL(hwrng_unregister);
383 static void __exit hwrng_exit(void)
385 mutex_lock(&rng_mutex);
388 mutex_unlock(&rng_mutex);
391 module_exit(hwrng_exit);
393 MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
394 MODULE_LICENSE("GPL");