Michael Buesch | 844dd05 | 2006-06-26 00:24:59 -0700 | [diff] [blame] | 1 | /* |
| 2 | Added support for the AMD Geode LX RNG |
| 3 | (c) Copyright 2004-2005 Advanced Micro Devices, Inc. |
| 4 | |
| 5 | derived from |
| 6 | |
| 7 | Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG) |
| 8 | (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com> |
| 9 | |
| 10 | derived from |
| 11 | |
| 12 | Hardware driver for the AMD 768 Random Number Generator (RNG) |
| 13 | (c) Copyright 2001 Red Hat Inc <alan@redhat.com> |
| 14 | |
| 15 | derived from |
| 16 | |
| 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> |
| 20 | |
| 21 | Added generic RNG API |
| 22 | Copyright 2006 Michael Buesch <mbuesch@freenet.de> |
| 23 | Copyright 2005 (c) MontaVista Software, Inc. |
| 24 | |
| 25 | Please read Documentation/hw_random.txt for details on use. |
| 26 | |
| 27 | ---------------------------------------------------------- |
| 28 | This software may be used and distributed according to the terms |
| 29 | of the GNU General Public License, incorporated herein by reference. |
| 30 | |
| 31 | */ |
| 32 | |
| 33 | |
| 34 | #include <linux/device.h> |
| 35 | #include <linux/hw_random.h> |
| 36 | #include <linux/module.h> |
| 37 | #include <linux/kernel.h> |
| 38 | #include <linux/fs.h> |
Al Viro | 914e263 | 2006-10-18 13:55:46 -0400 | [diff] [blame] | 39 | #include <linux/sched.h> |
Michael Buesch | 844dd05 | 2006-06-26 00:24:59 -0700 | [diff] [blame] | 40 | #include <linux/init.h> |
| 41 | #include <linux/miscdevice.h> |
| 42 | #include <linux/delay.h> |
| 43 | #include <asm/uaccess.h> |
| 44 | |
| 45 | |
| 46 | #define RNG_MODULE_NAME "hw_random" |
| 47 | #define PFX RNG_MODULE_NAME ": " |
| 48 | #define RNG_MISCDEV_MINOR 183 /* official */ |
| 49 | |
| 50 | |
| 51 | static struct hwrng *current_rng; |
| 52 | static LIST_HEAD(rng_list); |
| 53 | static DEFINE_MUTEX(rng_mutex); |
| 54 | |
| 55 | |
| 56 | static inline int hwrng_init(struct hwrng *rng) |
| 57 | { |
| 58 | if (!rng->init) |
| 59 | return 0; |
| 60 | return rng->init(rng); |
| 61 | } |
| 62 | |
| 63 | static inline void hwrng_cleanup(struct hwrng *rng) |
| 64 | { |
| 65 | if (rng && rng->cleanup) |
| 66 | rng->cleanup(rng); |
| 67 | } |
| 68 | |
| 69 | static inline int hwrng_data_present(struct hwrng *rng) |
| 70 | { |
| 71 | if (!rng->data_present) |
| 72 | return 1; |
| 73 | return rng->data_present(rng); |
| 74 | } |
| 75 | |
| 76 | static inline int hwrng_data_read(struct hwrng *rng, u32 *data) |
| 77 | { |
| 78 | return rng->data_read(rng, data); |
| 79 | } |
| 80 | |
| 81 | |
| 82 | static int rng_dev_open(struct inode *inode, struct file *filp) |
| 83 | { |
| 84 | /* enforce read-only access to this chrdev */ |
| 85 | if ((filp->f_mode & FMODE_READ) == 0) |
| 86 | return -EINVAL; |
| 87 | if (filp->f_mode & FMODE_WRITE) |
| 88 | return -EINVAL; |
| 89 | return 0; |
| 90 | } |
| 91 | |
| 92 | static ssize_t rng_dev_read(struct file *filp, char __user *buf, |
| 93 | size_t size, loff_t *offp) |
| 94 | { |
| 95 | u32 data; |
| 96 | ssize_t ret = 0; |
| 97 | int i, err = 0; |
| 98 | int data_present; |
| 99 | int bytes_read; |
| 100 | |
| 101 | while (size) { |
| 102 | err = -ERESTARTSYS; |
| 103 | if (mutex_lock_interruptible(&rng_mutex)) |
| 104 | goto out; |
| 105 | if (!current_rng) { |
| 106 | mutex_unlock(&rng_mutex); |
| 107 | err = -ENODEV; |
| 108 | goto out; |
| 109 | } |
| 110 | if (filp->f_flags & O_NONBLOCK) { |
| 111 | data_present = hwrng_data_present(current_rng); |
| 112 | } else { |
| 113 | /* Some RNG require some time between data_reads to gather |
| 114 | * new entropy. Poll it. |
| 115 | */ |
| 116 | for (i = 0; i < 20; i++) { |
| 117 | data_present = hwrng_data_present(current_rng); |
| 118 | if (data_present) |
| 119 | break; |
| 120 | udelay(10); |
| 121 | } |
| 122 | } |
| 123 | bytes_read = 0; |
| 124 | if (data_present) |
| 125 | bytes_read = hwrng_data_read(current_rng, &data); |
| 126 | mutex_unlock(&rng_mutex); |
| 127 | |
| 128 | err = -EAGAIN; |
| 129 | if (!bytes_read && (filp->f_flags & O_NONBLOCK)) |
| 130 | goto out; |
| 131 | |
| 132 | err = -EFAULT; |
| 133 | while (bytes_read && size) { |
| 134 | if (put_user((u8)data, buf++)) |
| 135 | goto out; |
| 136 | size--; |
| 137 | ret++; |
| 138 | bytes_read--; |
| 139 | data >>= 8; |
| 140 | } |
| 141 | |
| 142 | if (need_resched()) |
| 143 | schedule_timeout_interruptible(1); |
| 144 | err = -ERESTARTSYS; |
| 145 | if (signal_pending(current)) |
| 146 | goto out; |
| 147 | } |
| 148 | out: |
| 149 | return ret ? : err; |
| 150 | } |
| 151 | |
| 152 | |
Arjan van de Ven | 62322d2 | 2006-07-03 00:24:21 -0700 | [diff] [blame] | 153 | static const struct file_operations rng_chrdev_ops = { |
Michael Buesch | 844dd05 | 2006-06-26 00:24:59 -0700 | [diff] [blame] | 154 | .owner = THIS_MODULE, |
| 155 | .open = rng_dev_open, |
| 156 | .read = rng_dev_read, |
| 157 | }; |
| 158 | |
| 159 | static struct miscdevice rng_miscdev = { |
| 160 | .minor = RNG_MISCDEV_MINOR, |
| 161 | .name = RNG_MODULE_NAME, |
| 162 | .fops = &rng_chrdev_ops, |
| 163 | }; |
| 164 | |
| 165 | |
Greg Kroah-Hartman | 94fbcde | 2006-07-27 16:16:04 -0700 | [diff] [blame] | 166 | static ssize_t hwrng_attr_current_store(struct device *dev, |
| 167 | struct device_attribute *attr, |
Michael Buesch | 844dd05 | 2006-06-26 00:24:59 -0700 | [diff] [blame] | 168 | const char *buf, size_t len) |
| 169 | { |
| 170 | int err; |
| 171 | struct hwrng *rng; |
| 172 | |
| 173 | err = mutex_lock_interruptible(&rng_mutex); |
| 174 | if (err) |
| 175 | return -ERESTARTSYS; |
| 176 | err = -ENODEV; |
| 177 | list_for_each_entry(rng, &rng_list, list) { |
| 178 | if (strcmp(rng->name, buf) == 0) { |
| 179 | if (rng == current_rng) { |
| 180 | err = 0; |
| 181 | break; |
| 182 | } |
| 183 | err = hwrng_init(rng); |
| 184 | if (err) |
| 185 | break; |
| 186 | hwrng_cleanup(current_rng); |
| 187 | current_rng = rng; |
| 188 | err = 0; |
| 189 | break; |
| 190 | } |
| 191 | } |
| 192 | mutex_unlock(&rng_mutex); |
| 193 | |
| 194 | return err ? : len; |
| 195 | } |
| 196 | |
Greg Kroah-Hartman | 94fbcde | 2006-07-27 16:16:04 -0700 | [diff] [blame] | 197 | static ssize_t hwrng_attr_current_show(struct device *dev, |
| 198 | struct device_attribute *attr, |
Michael Buesch | 844dd05 | 2006-06-26 00:24:59 -0700 | [diff] [blame] | 199 | char *buf) |
| 200 | { |
| 201 | int err; |
| 202 | ssize_t ret; |
| 203 | const char *name = "none"; |
| 204 | |
| 205 | err = mutex_lock_interruptible(&rng_mutex); |
| 206 | if (err) |
| 207 | return -ERESTARTSYS; |
| 208 | if (current_rng) |
| 209 | name = current_rng->name; |
| 210 | ret = snprintf(buf, PAGE_SIZE, "%s\n", name); |
| 211 | mutex_unlock(&rng_mutex); |
| 212 | |
| 213 | return ret; |
| 214 | } |
| 215 | |
Greg Kroah-Hartman | 94fbcde | 2006-07-27 16:16:04 -0700 | [diff] [blame] | 216 | static ssize_t hwrng_attr_available_show(struct device *dev, |
| 217 | struct device_attribute *attr, |
Michael Buesch | 844dd05 | 2006-06-26 00:24:59 -0700 | [diff] [blame] | 218 | char *buf) |
| 219 | { |
| 220 | int err; |
| 221 | ssize_t ret = 0; |
| 222 | struct hwrng *rng; |
| 223 | |
| 224 | err = mutex_lock_interruptible(&rng_mutex); |
| 225 | if (err) |
| 226 | return -ERESTARTSYS; |
| 227 | buf[0] = '\0'; |
| 228 | list_for_each_entry(rng, &rng_list, list) { |
| 229 | strncat(buf, rng->name, PAGE_SIZE - ret - 1); |
| 230 | ret += strlen(rng->name); |
| 231 | strncat(buf, " ", PAGE_SIZE - ret - 1); |
| 232 | ret++; |
| 233 | } |
| 234 | strncat(buf, "\n", PAGE_SIZE - ret - 1); |
| 235 | ret++; |
| 236 | mutex_unlock(&rng_mutex); |
| 237 | |
| 238 | return ret; |
| 239 | } |
| 240 | |
Greg Kroah-Hartman | 94fbcde | 2006-07-27 16:16:04 -0700 | [diff] [blame] | 241 | static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR, |
| 242 | hwrng_attr_current_show, |
| 243 | hwrng_attr_current_store); |
| 244 | static DEVICE_ATTR(rng_available, S_IRUGO, |
| 245 | hwrng_attr_available_show, |
| 246 | NULL); |
Michael Buesch | 844dd05 | 2006-06-26 00:24:59 -0700 | [diff] [blame] | 247 | |
| 248 | |
| 249 | static void unregister_miscdev(void) |
| 250 | { |
Greg Kroah-Hartman | 94fbcde | 2006-07-27 16:16:04 -0700 | [diff] [blame] | 251 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available); |
| 252 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); |
Michael Buesch | 844dd05 | 2006-06-26 00:24:59 -0700 | [diff] [blame] | 253 | misc_deregister(&rng_miscdev); |
| 254 | } |
| 255 | |
| 256 | static int register_miscdev(void) |
| 257 | { |
| 258 | int err; |
| 259 | |
| 260 | err = misc_register(&rng_miscdev); |
| 261 | if (err) |
| 262 | goto out; |
Greg Kroah-Hartman | 94fbcde | 2006-07-27 16:16:04 -0700 | [diff] [blame] | 263 | err = device_create_file(rng_miscdev.this_device, |
| 264 | &dev_attr_rng_current); |
Michael Buesch | 844dd05 | 2006-06-26 00:24:59 -0700 | [diff] [blame] | 265 | if (err) |
| 266 | goto err_misc_dereg; |
Greg Kroah-Hartman | 94fbcde | 2006-07-27 16:16:04 -0700 | [diff] [blame] | 267 | err = device_create_file(rng_miscdev.this_device, |
| 268 | &dev_attr_rng_available); |
Michael Buesch | 844dd05 | 2006-06-26 00:24:59 -0700 | [diff] [blame] | 269 | if (err) |
| 270 | goto err_remove_current; |
| 271 | out: |
| 272 | return err; |
| 273 | |
| 274 | err_remove_current: |
Greg Kroah-Hartman | 94fbcde | 2006-07-27 16:16:04 -0700 | [diff] [blame] | 275 | device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current); |
Michael Buesch | 844dd05 | 2006-06-26 00:24:59 -0700 | [diff] [blame] | 276 | err_misc_dereg: |
| 277 | misc_deregister(&rng_miscdev); |
| 278 | goto out; |
| 279 | } |
| 280 | |
| 281 | int hwrng_register(struct hwrng *rng) |
| 282 | { |
| 283 | int must_register_misc; |
| 284 | int err = -EINVAL; |
| 285 | struct hwrng *old_rng, *tmp; |
| 286 | |
| 287 | if (rng->name == NULL || |
| 288 | rng->data_read == NULL) |
| 289 | goto out; |
| 290 | |
| 291 | mutex_lock(&rng_mutex); |
| 292 | |
| 293 | /* Must not register two RNGs with the same name. */ |
| 294 | err = -EEXIST; |
| 295 | list_for_each_entry(tmp, &rng_list, list) { |
| 296 | if (strcmp(tmp->name, rng->name) == 0) |
| 297 | goto out_unlock; |
| 298 | } |
| 299 | |
| 300 | must_register_misc = (current_rng == NULL); |
| 301 | old_rng = current_rng; |
| 302 | if (!old_rng) { |
| 303 | err = hwrng_init(rng); |
| 304 | if (err) |
| 305 | goto out_unlock; |
| 306 | current_rng = rng; |
| 307 | } |
| 308 | err = 0; |
| 309 | if (must_register_misc) { |
| 310 | err = register_miscdev(); |
| 311 | if (err) { |
| 312 | if (!old_rng) { |
| 313 | hwrng_cleanup(rng); |
| 314 | current_rng = NULL; |
| 315 | } |
| 316 | goto out_unlock; |
| 317 | } |
| 318 | } |
| 319 | INIT_LIST_HEAD(&rng->list); |
| 320 | list_add_tail(&rng->list, &rng_list); |
| 321 | out_unlock: |
| 322 | mutex_unlock(&rng_mutex); |
| 323 | out: |
| 324 | return err; |
| 325 | } |
| 326 | EXPORT_SYMBOL_GPL(hwrng_register); |
| 327 | |
| 328 | void hwrng_unregister(struct hwrng *rng) |
| 329 | { |
| 330 | int err; |
| 331 | |
| 332 | mutex_lock(&rng_mutex); |
| 333 | |
| 334 | list_del(&rng->list); |
| 335 | if (current_rng == rng) { |
| 336 | hwrng_cleanup(rng); |
| 337 | if (list_empty(&rng_list)) { |
| 338 | current_rng = NULL; |
| 339 | } else { |
| 340 | current_rng = list_entry(rng_list.prev, struct hwrng, list); |
| 341 | err = hwrng_init(current_rng); |
| 342 | if (err) |
| 343 | current_rng = NULL; |
| 344 | } |
| 345 | } |
| 346 | if (list_empty(&rng_list)) |
| 347 | unregister_miscdev(); |
| 348 | |
| 349 | mutex_unlock(&rng_mutex); |
| 350 | } |
| 351 | EXPORT_SYMBOL_GPL(hwrng_unregister); |
| 352 | |
| 353 | |
| 354 | MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); |
| 355 | MODULE_LICENSE("GPL"); |