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/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>
49 #define RNG_MODULE_NAME "hw_random"
50 #define PFX RNG_MODULE_NAME ": "
51 #define RNG_MISCDEV_MINOR 183 /* official */
54 static struct hwrng
*current_rng
;
55 static struct task_struct
*hwrng_fill
;
56 static LIST_HEAD(rng_list
);
57 /* Protects rng_list and current_rng */
58 static DEFINE_MUTEX(rng_mutex
);
59 /* Protects rng read functions, data_avail, rng_buffer and rng_fillbuf */
60 static DEFINE_MUTEX(reading_mutex
);
61 static int data_avail
;
62 static u8
*rng_buffer
, *rng_fillbuf
;
63 static unsigned short current_quality
;
64 static unsigned short default_quality
; /* = 0; default to "off" */
66 module_param(current_quality
, ushort
, 0644);
67 MODULE_PARM_DESC(current_quality
,
68 "current hwrng entropy estimation per mill");
69 module_param(default_quality
, ushort
, 0644);
70 MODULE_PARM_DESC(default_quality
,
71 "default entropy content of hwrng per mill");
73 static void drop_current_rng(void);
74 static int hwrng_init(struct hwrng
*rng
);
75 static void start_khwrngd(void);
77 static inline int rng_get_data(struct hwrng
*rng
, u8
*buffer
, size_t size
,
80 static size_t rng_buffer_size(void)
82 return SMP_CACHE_BYTES
< 32 ? 32 : SMP_CACHE_BYTES
;
85 static void add_early_randomness(struct hwrng
*rng
)
87 unsigned char bytes
[16];
90 mutex_lock(&reading_mutex
);
91 bytes_read
= rng_get_data(rng
, bytes
, sizeof(bytes
), 1);
92 mutex_unlock(&reading_mutex
);
94 add_device_randomness(bytes
, bytes_read
);
97 static inline void cleanup_rng(struct kref
*kref
)
99 struct hwrng
*rng
= container_of(kref
, struct hwrng
, ref
);
104 complete(&rng
->cleanup_done
);
107 static int set_current_rng(struct hwrng
*rng
)
111 BUG_ON(!mutex_is_locked(&rng_mutex
));
113 err
= hwrng_init(rng
);
123 static void drop_current_rng(void)
125 BUG_ON(!mutex_is_locked(&rng_mutex
));
129 /* decrease last reference for triggering the cleanup */
130 kref_put(¤t_rng
->ref
, cleanup_rng
);
134 /* Returns ERR_PTR(), NULL or refcounted hwrng */
135 static struct hwrng
*get_current_rng(void)
139 if (mutex_lock_interruptible(&rng_mutex
))
140 return ERR_PTR(-ERESTARTSYS
);
146 mutex_unlock(&rng_mutex
);
150 static void put_rng(struct hwrng
*rng
)
153 * Hold rng_mutex here so we serialize in case they set_current_rng
154 * on rng again immediately.
156 mutex_lock(&rng_mutex
);
158 kref_put(&rng
->ref
, cleanup_rng
);
159 mutex_unlock(&rng_mutex
);
162 static int hwrng_init(struct hwrng
*rng
)
164 if (kref_get_unless_zero(&rng
->ref
))
170 ret
= rng
->init(rng
);
175 kref_init(&rng
->ref
);
176 reinit_completion(&rng
->cleanup_done
);
179 add_early_randomness(rng
);
181 current_quality
= rng
->quality
? : default_quality
;
182 current_quality
&= 1023;
184 if (current_quality
== 0 && hwrng_fill
)
185 kthread_stop(hwrng_fill
);
186 if (current_quality
> 0 && !hwrng_fill
)
192 static int rng_dev_open(struct inode
*inode
, struct file
*filp
)
194 /* enforce read-only access to this chrdev */
195 if ((filp
->f_mode
& FMODE_READ
) == 0)
197 if (filp
->f_mode
& FMODE_WRITE
)
202 static inline int rng_get_data(struct hwrng
*rng
, u8
*buffer
, size_t size
,
206 BUG_ON(!mutex_is_locked(&reading_mutex
));
208 return rng
->read(rng
, (void *)buffer
, size
, wait
);
210 if (rng
->data_present
)
211 present
= rng
->data_present(rng
, wait
);
216 return rng
->data_read(rng
, (u32
*)buffer
);
221 static ssize_t
rng_dev_read(struct file
*filp
, char __user
*buf
,
222 size_t size
, loff_t
*offp
)
230 rng
= get_current_rng();
240 mutex_lock(&reading_mutex
);
242 bytes_read
= rng_get_data(rng
, rng_buffer
,
244 !(filp
->f_flags
& O_NONBLOCK
));
245 if (bytes_read
< 0) {
247 goto out_unlock_reading
;
249 data_avail
= bytes_read
;
253 if (filp
->f_flags
& O_NONBLOCK
) {
255 goto out_unlock_reading
;
264 if (copy_to_user(buf
+ ret
, rng_buffer
+ data_avail
,
267 goto out_unlock_reading
;
274 mutex_unlock(&reading_mutex
);
278 schedule_timeout_interruptible(1);
280 if (signal_pending(current
)) {
289 mutex_unlock(&reading_mutex
);
295 static const struct file_operations rng_chrdev_ops
= {
296 .owner
= THIS_MODULE
,
297 .open
= rng_dev_open
,
298 .read
= rng_dev_read
,
299 .llseek
= noop_llseek
,
302 static struct miscdevice rng_miscdev
= {
303 .minor
= RNG_MISCDEV_MINOR
,
304 .name
= RNG_MODULE_NAME
,
306 .fops
= &rng_chrdev_ops
,
310 static ssize_t
hwrng_attr_current_store(struct device
*dev
,
311 struct device_attribute
*attr
,
312 const char *buf
, size_t len
)
317 err
= mutex_lock_interruptible(&rng_mutex
);
321 list_for_each_entry(rng
, &rng_list
, list
) {
322 if (strcmp(rng
->name
, buf
) == 0) {
324 if (rng
!= current_rng
)
325 err
= set_current_rng(rng
);
329 mutex_unlock(&rng_mutex
);
334 static ssize_t
hwrng_attr_current_show(struct device
*dev
,
335 struct device_attribute
*attr
,
341 rng
= get_current_rng();
345 ret
= snprintf(buf
, PAGE_SIZE
, "%s\n", rng
? rng
->name
: "none");
351 static ssize_t
hwrng_attr_available_show(struct device
*dev
,
352 struct device_attribute
*attr
,
358 err
= mutex_lock_interruptible(&rng_mutex
);
362 list_for_each_entry(rng
, &rng_list
, list
) {
363 strlcat(buf
, rng
->name
, PAGE_SIZE
);
364 strlcat(buf
, " ", PAGE_SIZE
);
366 strlcat(buf
, "\n", PAGE_SIZE
);
367 mutex_unlock(&rng_mutex
);
372 static DEVICE_ATTR(rng_current
, S_IRUGO
| S_IWUSR
,
373 hwrng_attr_current_show
,
374 hwrng_attr_current_store
);
375 static DEVICE_ATTR(rng_available
, S_IRUGO
,
376 hwrng_attr_available_show
,
380 static void __exit
unregister_miscdev(void)
382 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_available
);
383 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_current
);
384 misc_deregister(&rng_miscdev
);
387 static int __init
register_miscdev(void)
391 err
= misc_register(&rng_miscdev
);
394 err
= device_create_file(rng_miscdev
.this_device
,
395 &dev_attr_rng_current
);
398 err
= device_create_file(rng_miscdev
.this_device
,
399 &dev_attr_rng_available
);
401 goto err_remove_current
;
406 device_remove_file(rng_miscdev
.this_device
, &dev_attr_rng_current
);
408 misc_deregister(&rng_miscdev
);
412 static int hwrng_fillfn(void *unused
)
416 while (!kthread_should_stop()) {
419 rng
= get_current_rng();
420 if (IS_ERR(rng
) || !rng
)
422 mutex_lock(&reading_mutex
);
423 rc
= rng_get_data(rng
, rng_fillbuf
,
424 rng_buffer_size(), 1);
425 mutex_unlock(&reading_mutex
);
428 pr_warn("hwrng: no data available\n");
429 msleep_interruptible(10000);
432 /* Outside lock, sure, but y'know: randomness. */
433 add_hwgenerator_randomness((void *)rng_fillbuf
, rc
,
434 rc
* current_quality
* 8 >> 10);
440 static void start_khwrngd(void)
442 hwrng_fill
= kthread_run(hwrng_fillfn
, NULL
, "hwrng");
443 if (hwrng_fill
== ERR_PTR(-ENOMEM
)) {
444 pr_err("hwrng_fill thread creation failed");
449 int hwrng_register(struct hwrng
*rng
)
452 struct hwrng
*old_rng
, *tmp
;
454 if (rng
->name
== NULL
||
455 (rng
->data_read
== NULL
&& rng
->read
== NULL
))
458 mutex_lock(&rng_mutex
);
460 /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
463 rng_buffer
= kmalloc(rng_buffer_size(), GFP_KERNEL
);
468 rng_fillbuf
= kmalloc(rng_buffer_size(), GFP_KERNEL
);
475 /* Must not register two RNGs with the same name. */
477 list_for_each_entry(tmp
, &rng_list
, list
) {
478 if (strcmp(tmp
->name
, rng
->name
) == 0)
482 init_completion(&rng
->cleanup_done
);
483 complete(&rng
->cleanup_done
);
485 old_rng
= current_rng
;
488 err
= set_current_rng(rng
);
492 list_add_tail(&rng
->list
, &rng_list
);
494 if (old_rng
&& !rng
->init
) {
496 * Use a new device's input to add some randomness to
497 * the system. If this rng device isn't going to be
498 * used right away, its init function hasn't been
499 * called yet; so only use the randomness from devices
500 * that don't need an init callback.
502 add_early_randomness(rng
);
506 mutex_unlock(&rng_mutex
);
510 EXPORT_SYMBOL_GPL(hwrng_register
);
512 void hwrng_unregister(struct hwrng
*rng
)
514 mutex_lock(&rng_mutex
);
516 list_del(&rng
->list
);
517 if (current_rng
== rng
) {
519 if (!list_empty(&rng_list
)) {
522 tail
= list_entry(rng_list
.prev
, struct hwrng
, list
);
524 set_current_rng(tail
);
528 if (list_empty(&rng_list
)) {
529 mutex_unlock(&rng_mutex
);
531 kthread_stop(hwrng_fill
);
533 mutex_unlock(&rng_mutex
);
535 wait_for_completion(&rng
->cleanup_done
);
537 EXPORT_SYMBOL_GPL(hwrng_unregister
);
539 static int __init
hwrng_modinit(void)
541 return register_miscdev();
544 static void __exit
hwrng_modexit(void)
546 mutex_lock(&rng_mutex
);
550 mutex_unlock(&rng_mutex
);
552 unregister_miscdev();
555 module_init(hwrng_modinit
);
556 module_exit(hwrng_modexit
);
558 MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
559 MODULE_LICENSE("GPL");