2 * chaoskey - driver for ChaosKey device from Altus Metrum.
4 * This device provides true random numbers using a noise source based
5 * on a reverse-biased p-n junction in avalanche breakdown. More
6 * details can be found at http://chaoskey.org
8 * The driver connects to the kernel hardware RNG interface to provide
9 * entropy for /dev/random and other kernel activities. It also offers
10 * a separate /dev/ entry to allow for direct access to the random
13 * Copyright © 2015 Keith Packard <keithp@keithp.com>
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; version 2 of the License.
19 * This program is distributed in the hope that it will be useful, but
20 * WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 * General Public License for more details.
25 #include <linux/module.h>
26 #include <linux/slab.h>
27 #include <linux/usb.h>
28 #include <linux/wait.h>
29 #include <linux/hw_random.h>
30 #include <linux/mutex.h>
31 #include <linux/uaccess.h>
33 static struct usb_driver chaoskey_driver
;
34 static struct usb_class_driver chaoskey_class
;
35 static int chaoskey_rng_read(struct hwrng
*rng
, void *data
,
36 size_t max
, bool wait
);
38 #define usb_dbg(usb_if, format, arg...) \
39 dev_dbg(&(usb_if)->dev, format, ## arg)
41 #define usb_err(usb_if, format, arg...) \
42 dev_err(&(usb_if)->dev, format, ## arg)
44 /* Version Information */
45 #define DRIVER_VERSION "v0.1"
46 #define DRIVER_AUTHOR "Keith Packard, keithp@keithp.com"
47 #define DRIVER_DESC "Altus Metrum ChaosKey driver"
48 #define DRIVER_SHORT "chaoskey"
50 MODULE_VERSION(DRIVER_VERSION
);
51 MODULE_AUTHOR(DRIVER_AUTHOR
);
52 MODULE_DESCRIPTION(DRIVER_DESC
);
53 MODULE_LICENSE("GPL");
55 #define CHAOSKEY_VENDOR_ID 0x1d50 /* OpenMoko */
56 #define CHAOSKEY_PRODUCT_ID 0x60c6 /* ChaosKey */
58 #define CHAOSKEY_BUF_LEN 64 /* max size of USB full speed packet */
60 #define NAK_TIMEOUT (HZ) /* stall/wait timeout for device */
62 #ifdef CONFIG_USB_DYNAMIC_MINORS
63 #define USB_CHAOSKEY_MINOR_BASE 0
66 /* IOWARRIOR_MINOR_BASE + 16, not official yet */
67 #define USB_CHAOSKEY_MINOR_BASE 224
70 static const struct usb_device_id chaoskey_table
[] = {
71 { USB_DEVICE(CHAOSKEY_VENDOR_ID
, CHAOSKEY_PRODUCT_ID
) },
74 MODULE_DEVICE_TABLE(usb
, chaoskey_table
);
76 static void chaos_read_callback(struct urb
*urb
);
78 /* Driver-local specific stuff */
80 struct usb_interface
*interface
;
83 struct mutex rng_lock
;
84 int open
; /* open count */
85 bool present
; /* device not disconnected */
86 bool reading
; /* ongoing IO */
87 int size
; /* size of buf */
88 int valid
; /* bytes of buf read */
89 int used
; /* bytes of buf consumed */
90 char *name
; /* product + serial */
91 struct hwrng hwrng
; /* Embedded struct for hwrng */
92 int hwrng_registered
; /* registered with hwrng API */
93 wait_queue_head_t wait_q
; /* for timeouts */
94 struct urb
*urb
; /* for performing IO */
98 static void chaoskey_free(struct chaoskey
*dev
)
101 usb_dbg(dev
->interface
, "free");
102 usb_free_urb(dev
->urb
);
109 static int chaoskey_probe(struct usb_interface
*interface
,
110 const struct usb_device_id
*id
)
112 struct usb_device
*udev
= interface_to_usbdev(interface
);
113 struct usb_host_interface
*altsetting
= interface
->cur_altsetting
;
116 struct chaoskey
*dev
;
117 int result
= -ENOMEM
;
120 usb_dbg(interface
, "probe %s-%s", udev
->product
, udev
->serial
);
122 /* Find the first bulk IN endpoint and its packet size */
123 for (i
= 0; i
< altsetting
->desc
.bNumEndpoints
; i
++) {
124 if (usb_endpoint_is_bulk_in(&altsetting
->endpoint
[i
].desc
)) {
125 in_ep
= usb_endpoint_num(&altsetting
->endpoint
[i
].desc
);
126 size
= usb_endpoint_maxp(&altsetting
->endpoint
[i
].desc
);
131 /* Validate endpoint and size */
133 usb_dbg(interface
, "no IN endpoint found");
137 usb_dbg(interface
, "invalid size (%d)", size
);
141 if (size
> CHAOSKEY_BUF_LEN
) {
142 usb_dbg(interface
, "size reduced from %d to %d\n",
143 size
, CHAOSKEY_BUF_LEN
);
144 size
= CHAOSKEY_BUF_LEN
;
147 /* Looks good, allocate and initialize */
149 dev
= kzalloc(sizeof(struct chaoskey
), GFP_KERNEL
);
154 dev
->buf
= kmalloc(size
, GFP_KERNEL
);
156 if (dev
->buf
== NULL
)
159 dev
->urb
= usb_alloc_urb(0, GFP_KERNEL
);
164 usb_fill_bulk_urb(dev
->urb
,
166 usb_rcvbulkpipe(udev
, in_ep
),
172 /* Construct a name using the product and serial values. Each
173 * device needs a unique name for the hwrng code
176 if (udev
->product
&& udev
->serial
) {
177 dev
->name
= kmalloc(strlen(udev
->product
) + 1 +
178 strlen(udev
->serial
) + 1, GFP_KERNEL
);
179 if (dev
->name
== NULL
)
182 strcpy(dev
->name
, udev
->product
);
183 strcat(dev
->name
, "-");
184 strcat(dev
->name
, udev
->serial
);
187 dev
->interface
= interface
;
194 init_waitqueue_head(&dev
->wait_q
);
196 mutex_init(&dev
->lock
);
197 mutex_init(&dev
->rng_lock
);
199 usb_set_intfdata(interface
, dev
);
201 result
= usb_register_dev(interface
, &chaoskey_class
);
203 usb_err(interface
, "Unable to allocate minor number.");
207 dev
->hwrng
.name
= dev
->name
? dev
->name
: chaoskey_driver
.name
;
208 dev
->hwrng
.read
= chaoskey_rng_read
;
210 /* Set the 'quality' metric. Quality is measured in units of
211 * 1/1024's of a bit ("mills"). This should be set to 1024,
212 * but there is a bug in the hwrng core which masks it with
215 * The patch that has been merged to the crypto development
216 * tree for that bug limits the value to 1024 at most, so by
217 * setting this to 1024 + 1023, we get 1023 before the fix is
218 * merged and 1024 afterwards. We'll patch this driver once
219 * both bits of code are in the same tree.
221 dev
->hwrng
.quality
= 1024 + 1023;
223 dev
->hwrng_registered
= (hwrng_register(&dev
->hwrng
) == 0);
224 if (!dev
->hwrng_registered
)
225 usb_err(interface
, "Unable to register with hwrng");
227 usb_enable_autosuspend(udev
);
229 usb_dbg(interface
, "chaoskey probe success, size %d", dev
->size
);
233 usb_set_intfdata(interface
, NULL
);
238 static void chaoskey_disconnect(struct usb_interface
*interface
)
240 struct chaoskey
*dev
;
242 usb_dbg(interface
, "disconnect");
243 dev
= usb_get_intfdata(interface
);
245 usb_dbg(interface
, "disconnect failed - no dev");
249 if (dev
->hwrng_registered
)
250 hwrng_unregister(&dev
->hwrng
);
252 usb_deregister_dev(interface
, &chaoskey_class
);
254 usb_set_intfdata(interface
, NULL
);
255 mutex_lock(&dev
->lock
);
258 usb_poison_urb(dev
->urb
);
261 mutex_unlock(&dev
->lock
);
264 mutex_unlock(&dev
->lock
);
266 usb_dbg(interface
, "disconnect done");
269 static int chaoskey_open(struct inode
*inode
, struct file
*file
)
271 struct chaoskey
*dev
;
272 struct usb_interface
*interface
;
274 /* get the interface from minor number and driver information */
275 interface
= usb_find_interface(&chaoskey_driver
, iminor(inode
));
279 usb_dbg(interface
, "open");
281 dev
= usb_get_intfdata(interface
);
283 usb_dbg(interface
, "open (dev)");
287 file
->private_data
= dev
;
288 mutex_lock(&dev
->lock
);
290 mutex_unlock(&dev
->lock
);
292 usb_dbg(interface
, "open success");
296 static int chaoskey_release(struct inode
*inode
, struct file
*file
)
298 struct chaoskey
*dev
= file
->private_data
;
299 struct usb_interface
*interface
;
304 interface
= dev
->interface
;
306 usb_dbg(interface
, "release");
308 mutex_lock(&dev
->lock
);
310 usb_dbg(interface
, "open count at release is %d", dev
->open
);
312 if (dev
->open
<= 0) {
313 usb_dbg(interface
, "invalid open count (%d)", dev
->open
);
314 mutex_unlock(&dev
->lock
);
321 if (dev
->open
== 0) {
322 mutex_unlock(&dev
->lock
);
325 mutex_unlock(&dev
->lock
);
327 mutex_unlock(&dev
->lock
);
329 usb_dbg(interface
, "release success");
333 static void chaos_read_callback(struct urb
*urb
)
335 struct chaoskey
*dev
= urb
->context
;
336 int status
= urb
->status
;
338 usb_dbg(dev
->interface
, "callback status (%d)", status
);
341 dev
->valid
= urb
->actual_length
;
347 /* must be seen first before validity is announced */
350 dev
->reading
= false;
351 wake_up(&dev
->wait_q
);
354 /* Fill the buffer. Called with dev->lock held
356 static int _chaoskey_fill(struct chaoskey
*dev
)
361 usb_dbg(dev
->interface
, "fill");
363 /* Return immediately if someone called before the buffer was
365 if (dev
->valid
!= dev
->used
) {
366 usb_dbg(dev
->interface
, "not empty yet (valid %d used %d)",
367 dev
->valid
, dev
->used
);
371 /* Bail if the device has been removed */
373 usb_dbg(dev
->interface
, "device not present");
377 /* Make sure the device is awake */
378 result
= usb_autopm_get_interface(dev
->interface
);
380 usb_dbg(dev
->interface
, "wakeup failed (result %d)", result
);
385 result
= usb_submit_urb(dev
->urb
, GFP_KERNEL
);
387 result
= usb_translate_errors(result
);
388 dev
->reading
= false;
392 result
= wait_event_interruptible_timeout(
405 /* Let the device go back to sleep eventually */
406 usb_autopm_put_interface(dev
->interface
);
408 usb_dbg(dev
->interface
, "read %d bytes", dev
->valid
);
413 static ssize_t
chaoskey_read(struct file
*file
,
418 struct chaoskey
*dev
;
419 ssize_t read_count
= 0;
422 unsigned long remain
;
424 dev
= file
->private_data
;
426 if (dev
== NULL
|| !dev
->present
)
429 usb_dbg(dev
->interface
, "read %zu", count
);
433 /* Grab the rng_lock briefly to ensure that the hwrng interface
434 * gets priority over other user access
436 result
= mutex_lock_interruptible(&dev
->rng_lock
);
439 mutex_unlock(&dev
->rng_lock
);
441 result
= mutex_lock_interruptible(&dev
->lock
);
444 if (dev
->valid
== dev
->used
) {
445 result
= _chaoskey_fill(dev
);
447 mutex_unlock(&dev
->lock
);
452 this_time
= dev
->valid
- dev
->used
;
453 if (this_time
> count
)
456 remain
= copy_to_user(buffer
, dev
->buf
+ dev
->used
, this_time
);
460 /* Consume the bytes that were copied so we don't leak
463 dev
->used
+= this_time
- remain
;
464 mutex_unlock(&dev
->lock
);
469 read_count
+= this_time
;
471 dev
->used
+= this_time
;
472 mutex_unlock(&dev
->lock
);
476 usb_dbg(dev
->interface
, "read %zu bytes", read_count
);
479 usb_dbg(dev
->interface
, "empty read, result %d", result
);
480 if (result
== -ETIMEDOUT
)
485 static int chaoskey_rng_read(struct hwrng
*rng
, void *data
,
486 size_t max
, bool wait
)
488 struct chaoskey
*dev
= container_of(rng
, struct chaoskey
, hwrng
);
491 usb_dbg(dev
->interface
, "rng_read max %zu wait %d", max
, wait
);
494 usb_dbg(dev
->interface
, "device not present");
498 /* Hold the rng_lock until we acquire the device lock so that
499 * this operation gets priority over other user access to the
502 mutex_lock(&dev
->rng_lock
);
504 mutex_lock(&dev
->lock
);
506 mutex_unlock(&dev
->rng_lock
);
508 /* Try to fill the buffer if empty. It doesn't actually matter
509 * if _chaoskey_fill works; we'll just return zero bytes as
510 * the buffer will still be empty
512 if (dev
->valid
== dev
->used
)
513 (void) _chaoskey_fill(dev
);
515 this_time
= dev
->valid
- dev
->used
;
519 memcpy(data
, dev
->buf
+ dev
->used
, this_time
);
521 dev
->used
+= this_time
;
523 mutex_unlock(&dev
->lock
);
525 usb_dbg(dev
->interface
, "rng_read this_time %d\n", this_time
);
530 static int chaoskey_suspend(struct usb_interface
*interface
,
531 pm_message_t message
)
533 usb_dbg(interface
, "suspend");
537 static int chaoskey_resume(struct usb_interface
*interface
)
539 usb_dbg(interface
, "resume");
543 #define chaoskey_suspend NULL
544 #define chaoskey_resume NULL
547 /* file operation pointers */
548 static const struct file_operations chaoskey_fops
= {
549 .owner
= THIS_MODULE
,
550 .read
= chaoskey_read
,
551 .open
= chaoskey_open
,
552 .release
= chaoskey_release
,
553 .llseek
= default_llseek
,
556 /* class driver information */
557 static struct usb_class_driver chaoskey_class
= {
558 .name
= "chaoskey%d",
559 .fops
= &chaoskey_fops
,
560 .minor_base
= USB_CHAOSKEY_MINOR_BASE
,
563 /* usb specific object needed to register this driver with the usb subsystem */
564 static struct usb_driver chaoskey_driver
= {
565 .name
= DRIVER_SHORT
,
566 .probe
= chaoskey_probe
,
567 .disconnect
= chaoskey_disconnect
,
568 .suspend
= chaoskey_suspend
,
569 .resume
= chaoskey_resume
,
570 .reset_resume
= chaoskey_resume
,
571 .id_table
= chaoskey_table
,
572 .supports_autosuspend
= 1,
575 module_usb_driver(chaoskey_driver
);