1 /* 2 * CMOS/NV-RAM driver for Linux 3 * 4 * Copyright (C) 1997 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de> 5 * idea by and with help from Richard Jelinek <rj@suse.de> 6 * Portions copyright (c) 2001,2002 Sun Microsystems (thockin@sun.com) 7 * 8 * This driver allows you to access the contents of the non-volatile memory in 9 * the mc146818rtc.h real-time clock. This chip is built into all PCs and into 10 * many Atari machines. In the former it's called "CMOS-RAM", in the latter 11 * "NVRAM" (NV stands for non-volatile). 12 * 13 * The data are supplied as a (seekable) character device, /dev/nvram. The 14 * size of this file is dependent on the controller. The usual size is 114, 15 * the number of freely available bytes in the memory (i.e., not used by the 16 * RTC itself). 17 * 18 * Checksums over the NVRAM contents are managed by this driver. In case of a 19 * bad checksum, reads and writes return -EIO. The checksum can be initialized 20 * to a sane state either by ioctl(NVRAM_INIT) (clear whole NVRAM) or 21 * ioctl(NVRAM_SETCKS) (doesn't change contents, just makes checksum valid 22 * again; use with care!) 23 * 24 * This file also provides some functions for other parts of the kernel that 25 * want to access the NVRAM: nvram_{read,write,check_checksum,set_checksum}. 26 * Obviously this can be used only if this driver is always configured into 27 * the kernel and is not a module. Since the functions are used by some Atari 28 * drivers, this is the case on the Atari. 29 * 30 * 31 * 1.1 Cesar Barros: SMP locking fixes 32 * added changelog 33 * 1.2 Erik Gilling: Cobalt Networks support 34 * Tim Hockin: general cleanup, Cobalt support 35 */ 36 37 #define NVRAM_VERSION "1.2" 38 39 #include <linux/module.h> 40 #include <linux/smp_lock.h> 41 #include <linux/nvram.h> 42 43 #define PC 1 44 #define ATARI 2 45 46 /* select machine configuration */ 47 #if defined(CONFIG_ATARI) 48 # define MACH ATARI 49 #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) /* and others?? */ 50 # define MACH PC 51 #else 52 # error Cannot build nvram driver for this machine configuration. 53 #endif 54 55 #if MACH == PC 56 57 /* RTC in a PC */ 58 #define CHECK_DRIVER_INIT() 1 59 60 /* On PCs, the checksum is built only over bytes 2..31 */ 61 #define PC_CKS_RANGE_START 2 62 #define PC_CKS_RANGE_END 31 63 #define PC_CKS_LOC 32 64 #define NVRAM_BYTES (128-NVRAM_FIRST_BYTE) 65 66 #define mach_check_checksum pc_check_checksum 67 #define mach_set_checksum pc_set_checksum 68 #define mach_proc_infos pc_proc_infos 69 70 #endif 71 72 #if MACH == ATARI 73 74 /* Special parameters for RTC in Atari machines */ 75 #include <asm/atarihw.h> 76 #include <asm/atariints.h> 77 #define RTC_PORT(x) (TT_RTC_BAS + 2*(x)) 78 #define CHECK_DRIVER_INIT() (MACH_IS_ATARI && ATARIHW_PRESENT(TT_CLK)) 79 80 #define NVRAM_BYTES 50 81 82 /* On Ataris, the checksum is over all bytes except the checksum bytes 83 * themselves; these are at the very end */ 84 #define ATARI_CKS_RANGE_START 0 85 #define ATARI_CKS_RANGE_END 47 86 #define ATARI_CKS_LOC 48 87 88 #define mach_check_checksum atari_check_checksum 89 #define mach_set_checksum atari_set_checksum 90 #define mach_proc_infos atari_proc_infos 91 92 #endif 93 94 /* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with 95 * rtc_lock held. Due to the index-port/data-port design of the RTC, we 96 * don't want two different things trying to get to it at once. (e.g. the 97 * periodic 11 min sync from time.c vs. this driver.) 98 */ 99 100 #include <linux/types.h> 101 #include <linux/errno.h> 102 #include <linux/miscdevice.h> 103 #include <linux/slab.h> 104 #include <linux/ioport.h> 105 #include <linux/fcntl.h> 106 #include <linux/mc146818rtc.h> 107 #include <linux/init.h> 108 #include <linux/proc_fs.h> 109 #include <linux/spinlock.h> 110 111 #include <asm/io.h> 112 #include <asm/uaccess.h> 113 #include <asm/system.h> 114 115 static DEFINE_SPINLOCK(nvram_state_lock); 116 static int nvram_open_cnt; /* #times opened */ 117 static int nvram_open_mode; /* special open modes */ 118 #define NVRAM_WRITE 1 /* opened for writing (exclusive) */ 119 #define NVRAM_EXCL 2 /* opened with O_EXCL */ 120 121 static int mach_check_checksum(void); 122 static void mach_set_checksum(void); 123 124 #ifdef CONFIG_PROC_FS 125 static int mach_proc_infos(unsigned char *contents, char *buffer, int *len, 126 off_t *begin, off_t offset, int size); 127 #endif 128 129 /* 130 * These functions are provided to be called internally or by other parts of 131 * the kernel. It's up to the caller to ensure correct checksum before reading 132 * or after writing (needs to be done only once). 133 * 134 * It is worth noting that these functions all access bytes of general 135 * purpose memory in the NVRAM - that is to say, they all add the 136 * NVRAM_FIRST_BYTE offset. Pass them offsets into NVRAM as if you did not 137 * know about the RTC cruft. 138 */ 139 140 unsigned char 141 __nvram_read_byte(int i) 142 { 143 return CMOS_READ(NVRAM_FIRST_BYTE + i); 144 } 145 146 unsigned char 147 nvram_read_byte(int i) 148 { 149 unsigned long flags; 150 unsigned char c; 151 152 spin_lock_irqsave(&rtc_lock, flags); 153 c = __nvram_read_byte(i); 154 spin_unlock_irqrestore(&rtc_lock, flags); 155 return c; 156 } 157 158 /* This races nicely with trying to read with checksum checking (nvram_read) */ 159 void 160 __nvram_write_byte(unsigned char c, int i) 161 { 162 CMOS_WRITE(c, NVRAM_FIRST_BYTE + i); 163 } 164 165 void 166 nvram_write_byte(unsigned char c, int i) 167 { 168 unsigned long flags; 169 170 spin_lock_irqsave(&rtc_lock, flags); 171 __nvram_write_byte(c, i); 172 spin_unlock_irqrestore(&rtc_lock, flags); 173 } 174 175 int 176 __nvram_check_checksum(void) 177 { 178 return mach_check_checksum(); 179 } 180 181 int 182 nvram_check_checksum(void) 183 { 184 unsigned long flags; 185 int rv; 186 187 spin_lock_irqsave(&rtc_lock, flags); 188 rv = __nvram_check_checksum(); 189 spin_unlock_irqrestore(&rtc_lock, flags); 190 return rv; 191 } 192 193 static void 194 __nvram_set_checksum(void) 195 { 196 mach_set_checksum(); 197 } 198 199 #if 0 200 void 201 nvram_set_checksum(void) 202 { 203 unsigned long flags; 204 205 spin_lock_irqsave(&rtc_lock, flags); 206 __nvram_set_checksum(); 207 spin_unlock_irqrestore(&rtc_lock, flags); 208 } 209 #endif /* 0 */ 210 211 /* 212 * The are the file operation function for user access to /dev/nvram 213 */ 214 215 static loff_t nvram_llseek(struct file *file,loff_t offset, int origin ) 216 { 217 lock_kernel(); 218 switch (origin) { 219 case 0: 220 /* nothing to do */ 221 break; 222 case 1: 223 offset += file->f_pos; 224 break; 225 case 2: 226 offset += NVRAM_BYTES; 227 break; 228 } 229 unlock_kernel(); 230 return (offset >= 0) ? (file->f_pos = offset) : -EINVAL; 231 } 232 233 static ssize_t 234 nvram_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) 235 { 236 unsigned char contents[NVRAM_BYTES]; 237 unsigned i = *ppos; 238 unsigned char *tmp; 239 240 spin_lock_irq(&rtc_lock); 241 242 if (!__nvram_check_checksum()) 243 goto checksum_err; 244 245 for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp) 246 *tmp = __nvram_read_byte(i); 247 248 spin_unlock_irq(&rtc_lock); 249 250 if (copy_to_user(buf, contents, tmp - contents)) 251 return -EFAULT; 252 253 *ppos = i; 254 255 return tmp - contents; 256 257 checksum_err: 258 spin_unlock_irq(&rtc_lock); 259 return -EIO; 260 } 261 262 static ssize_t 263 nvram_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 264 { 265 unsigned char contents[NVRAM_BYTES]; 266 unsigned i = *ppos; 267 unsigned char *tmp; 268 int len; 269 270 len = (NVRAM_BYTES - i) < count ? (NVRAM_BYTES - i) : count; 271 if (copy_from_user(contents, buf, len)) 272 return -EFAULT; 273 274 spin_lock_irq(&rtc_lock); 275 276 if (!__nvram_check_checksum()) 277 goto checksum_err; 278 279 for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp) 280 __nvram_write_byte(*tmp, i); 281 282 __nvram_set_checksum(); 283 284 spin_unlock_irq(&rtc_lock); 285 286 *ppos = i; 287 288 return tmp - contents; 289 290 checksum_err: 291 spin_unlock_irq(&rtc_lock); 292 return -EIO; 293 } 294 295 static int 296 nvram_ioctl(struct inode *inode, struct file *file, 297 unsigned int cmd, unsigned long arg) 298 { 299 int i; 300 301 switch (cmd) { 302 303 case NVRAM_INIT: 304 /* initialize NVRAM contents and checksum */ 305 if (!capable(CAP_SYS_ADMIN)) 306 return -EACCES; 307 308 spin_lock_irq(&rtc_lock); 309 310 for (i = 0; i < NVRAM_BYTES; ++i) 311 __nvram_write_byte(0, i); 312 __nvram_set_checksum(); 313 314 spin_unlock_irq(&rtc_lock); 315 return 0; 316 317 case NVRAM_SETCKS: 318 /* just set checksum, contents unchanged (maybe useful after 319 * checksum garbaged somehow...) */ 320 if (!capable(CAP_SYS_ADMIN)) 321 return -EACCES; 322 323 spin_lock_irq(&rtc_lock); 324 __nvram_set_checksum(); 325 spin_unlock_irq(&rtc_lock); 326 return 0; 327 328 default: 329 return -ENOTTY; 330 } 331 } 332 333 static int 334 nvram_open(struct inode *inode, struct file *file) 335 { 336 spin_lock(&nvram_state_lock); 337 338 if ((nvram_open_cnt && (file->f_flags & O_EXCL)) || 339 (nvram_open_mode & NVRAM_EXCL) || 340 ((file->f_mode & 2) && (nvram_open_mode & NVRAM_WRITE))) { 341 spin_unlock(&nvram_state_lock); 342 return -EBUSY; 343 } 344 345 if (file->f_flags & O_EXCL) 346 nvram_open_mode |= NVRAM_EXCL; 347 if (file->f_mode & 2) 348 nvram_open_mode |= NVRAM_WRITE; 349 nvram_open_cnt++; 350 351 spin_unlock(&nvram_state_lock); 352 353 return 0; 354 } 355 356 static int 357 nvram_release(struct inode *inode, struct file *file) 358 { 359 spin_lock(&nvram_state_lock); 360 361 nvram_open_cnt--; 362 363 /* if only one instance is open, clear the EXCL bit */ 364 if (nvram_open_mode & NVRAM_EXCL) 365 nvram_open_mode &= ~NVRAM_EXCL; 366 if (file->f_mode & 2) 367 nvram_open_mode &= ~NVRAM_WRITE; 368 369 spin_unlock(&nvram_state_lock); 370 371 return 0; 372 } 373 374 #ifndef CONFIG_PROC_FS 375 static int 376 nvram_read_proc(char *buffer, char **start, off_t offset, 377 int size, int *eof, void *data) 378 { 379 return 0; 380 } 381 #else 382 383 static int 384 nvram_read_proc(char *buffer, char **start, off_t offset, 385 int size, int *eof, void *data) 386 { 387 unsigned char contents[NVRAM_BYTES]; 388 int i, len = 0; 389 off_t begin = 0; 390 391 spin_lock_irq(&rtc_lock); 392 for (i = 0; i < NVRAM_BYTES; ++i) 393 contents[i] = __nvram_read_byte(i); 394 spin_unlock_irq(&rtc_lock); 395 396 *eof = mach_proc_infos(contents, buffer, &len, &begin, offset, size); 397 398 if (offset >= begin + len) 399 return 0; 400 *start = buffer + (offset - begin); 401 return (size < begin + len - offset) ? size : begin + len - offset; 402 403 } 404 405 /* This macro frees the machine specific function from bounds checking and 406 * this like that... */ 407 #define PRINT_PROC(fmt,args...) \ 408 do { \ 409 *len += sprintf(buffer+*len, fmt, ##args); \ 410 if (*begin + *len > offset + size) \ 411 return 0; \ 412 if (*begin + *len < offset) { \ 413 *begin += *len; \ 414 *len = 0; \ 415 } \ 416 } while(0) 417 418 #endif /* CONFIG_PROC_FS */ 419 420 static const struct file_operations nvram_fops = { 421 .owner = THIS_MODULE, 422 .llseek = nvram_llseek, 423 .read = nvram_read, 424 .write = nvram_write, 425 .ioctl = nvram_ioctl, 426 .open = nvram_open, 427 .release = nvram_release, 428 }; 429 430 static struct miscdevice nvram_dev = { 431 NVRAM_MINOR, 432 "nvram", 433 &nvram_fops 434 }; 435 436 static int __init 437 nvram_init(void) 438 { 439 int ret; 440 441 /* First test whether the driver should init at all */ 442 if (!CHECK_DRIVER_INIT()) 443 return -ENXIO; 444 445 ret = misc_register(&nvram_dev); 446 if (ret) { 447 printk(KERN_ERR "nvram: can't misc_register on minor=%d\n", 448 NVRAM_MINOR); 449 goto out; 450 } 451 if (!create_proc_read_entry("driver/nvram", 0, NULL, nvram_read_proc, 452 NULL)) { 453 printk(KERN_ERR "nvram: can't create /proc/driver/nvram\n"); 454 ret = -ENOMEM; 455 goto outmisc; 456 } 457 ret = 0; 458 printk(KERN_INFO "Non-volatile memory driver v" NVRAM_VERSION "\n"); 459 out: 460 return ret; 461 outmisc: 462 misc_deregister(&nvram_dev); 463 goto out; 464 } 465 466 static void __exit 467 nvram_cleanup_module(void) 468 { 469 remove_proc_entry("driver/nvram", NULL); 470 misc_deregister(&nvram_dev); 471 } 472 473 module_init(nvram_init); 474 module_exit(nvram_cleanup_module); 475 476 /* 477 * Machine specific functions 478 */ 479 480 #if MACH == PC 481 482 static int 483 pc_check_checksum(void) 484 { 485 int i; 486 unsigned short sum = 0; 487 unsigned short expect; 488 489 for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i) 490 sum += __nvram_read_byte(i); 491 expect = __nvram_read_byte(PC_CKS_LOC)<<8 | 492 __nvram_read_byte(PC_CKS_LOC+1); 493 return ((sum & 0xffff) == expect); 494 } 495 496 static void 497 pc_set_checksum(void) 498 { 499 int i; 500 unsigned short sum = 0; 501 502 for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i) 503 sum += __nvram_read_byte(i); 504 __nvram_write_byte(sum >> 8, PC_CKS_LOC); 505 __nvram_write_byte(sum & 0xff, PC_CKS_LOC + 1); 506 } 507 508 #ifdef CONFIG_PROC_FS 509 510 static char *floppy_types[] = { 511 "none", "5.25'' 360k", "5.25'' 1.2M", "3.5'' 720k", "3.5'' 1.44M", 512 "3.5'' 2.88M", "3.5'' 2.88M" 513 }; 514 515 static char *gfx_types[] = { 516 "EGA, VGA, ... (with BIOS)", 517 "CGA (40 cols)", 518 "CGA (80 cols)", 519 "monochrome", 520 }; 521 522 static int 523 pc_proc_infos(unsigned char *nvram, char *buffer, int *len, 524 off_t *begin, off_t offset, int size) 525 { 526 int checksum; 527 int type; 528 529 spin_lock_irq(&rtc_lock); 530 checksum = __nvram_check_checksum(); 531 spin_unlock_irq(&rtc_lock); 532 533 PRINT_PROC("Checksum status: %svalid\n", checksum ? "" : "not "); 534 535 PRINT_PROC("# floppies : %d\n", 536 (nvram[6] & 1) ? (nvram[6] >> 6) + 1 : 0); 537 PRINT_PROC("Floppy 0 type : "); 538 type = nvram[2] >> 4; 539 if (type < ARRAY_SIZE(floppy_types)) 540 PRINT_PROC("%s\n", floppy_types[type]); 541 else 542 PRINT_PROC("%d (unknown)\n", type); 543 PRINT_PROC("Floppy 1 type : "); 544 type = nvram[2] & 0x0f; 545 if (type < ARRAY_SIZE(floppy_types)) 546 PRINT_PROC("%s\n", floppy_types[type]); 547 else 548 PRINT_PROC("%d (unknown)\n", type); 549 550 PRINT_PROC("HD 0 type : "); 551 type = nvram[4] >> 4; 552 if (type) 553 PRINT_PROC("%02x\n", type == 0x0f ? nvram[11] : type); 554 else 555 PRINT_PROC("none\n"); 556 557 PRINT_PROC("HD 1 type : "); 558 type = nvram[4] & 0x0f; 559 if (type) 560 PRINT_PROC("%02x\n", type == 0x0f ? nvram[12] : type); 561 else 562 PRINT_PROC("none\n"); 563 564 PRINT_PROC("HD type 48 data: %d/%d/%d C/H/S, precomp %d, lz %d\n", 565 nvram[18] | (nvram[19] << 8), 566 nvram[20], nvram[25], 567 nvram[21] | (nvram[22] << 8), nvram[23] | (nvram[24] << 8)); 568 PRINT_PROC("HD type 49 data: %d/%d/%d C/H/S, precomp %d, lz %d\n", 569 nvram[39] | (nvram[40] << 8), 570 nvram[41], nvram[46], 571 nvram[42] | (nvram[43] << 8), nvram[44] | (nvram[45] << 8)); 572 573 PRINT_PROC("DOS base memory: %d kB\n", nvram[7] | (nvram[8] << 8)); 574 PRINT_PROC("Extended memory: %d kB (configured), %d kB (tested)\n", 575 nvram[9] | (nvram[10] << 8), nvram[34] | (nvram[35] << 8)); 576 577 PRINT_PROC("Gfx adapter : %s\n", gfx_types[(nvram[6] >> 4) & 3]); 578 579 PRINT_PROC("FPU : %sinstalled\n", 580 (nvram[6] & 2) ? "" : "not "); 581 582 return 1; 583 } 584 #endif 585 586 #endif /* MACH == PC */ 587 588 #if MACH == ATARI 589 590 static int 591 atari_check_checksum(void) 592 { 593 int i; 594 unsigned char sum = 0; 595 596 for (i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i) 597 sum += __nvram_read_byte(i); 598 return (__nvram_read_byte(ATARI_CKS_LOC) == (~sum & 0xff) && 599 __nvram_read_byte(ATARI_CKS_LOC + 1) == (sum & 0xff)); 600 } 601 602 static void 603 atari_set_checksum(void) 604 { 605 int i; 606 unsigned char sum = 0; 607 608 for (i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i) 609 sum += __nvram_read_byte(i); 610 __nvram_write_byte(~sum, ATARI_CKS_LOC); 611 __nvram_write_byte(sum, ATARI_CKS_LOC + 1); 612 } 613 614 #ifdef CONFIG_PROC_FS 615 616 static struct { 617 unsigned char val; 618 char *name; 619 } boot_prefs[] = { 620 { 0x80, "TOS" }, 621 { 0x40, "ASV" }, 622 { 0x20, "NetBSD (?)" }, 623 { 0x10, "Linux" }, 624 { 0x00, "unspecified" } 625 }; 626 627 static char *languages[] = { 628 "English (US)", 629 "German", 630 "French", 631 "English (UK)", 632 "Spanish", 633 "Italian", 634 "6 (undefined)", 635 "Swiss (French)", 636 "Swiss (German)" 637 }; 638 639 static char *dateformat[] = { 640 "MM%cDD%cYY", 641 "DD%cMM%cYY", 642 "YY%cMM%cDD", 643 "YY%cDD%cMM", 644 "4 (undefined)", 645 "5 (undefined)", 646 "6 (undefined)", 647 "7 (undefined)" 648 }; 649 650 static char *colors[] = { 651 "2", "4", "16", "256", "65536", "??", "??", "??" 652 }; 653 654 static int 655 atari_proc_infos(unsigned char *nvram, char *buffer, int *len, 656 off_t *begin, off_t offset, int size) 657 { 658 int checksum = nvram_check_checksum(); 659 int i; 660 unsigned vmode; 661 662 PRINT_PROC("Checksum status : %svalid\n", checksum ? "" : "not "); 663 664 PRINT_PROC("Boot preference : "); 665 for (i = ARRAY_SIZE(boot_prefs) - 1; i >= 0; --i) { 666 if (nvram[1] == boot_prefs[i].val) { 667 PRINT_PROC("%s\n", boot_prefs[i].name); 668 break; 669 } 670 } 671 if (i < 0) 672 PRINT_PROC("0x%02x (undefined)\n", nvram[1]); 673 674 PRINT_PROC("SCSI arbitration : %s\n", 675 (nvram[16] & 0x80) ? "on" : "off"); 676 PRINT_PROC("SCSI host ID : "); 677 if (nvram[16] & 0x80) 678 PRINT_PROC("%d\n", nvram[16] & 7); 679 else 680 PRINT_PROC("n/a\n"); 681 682 /* the following entries are defined only for the Falcon */ 683 if ((atari_mch_cookie >> 16) != ATARI_MCH_FALCON) 684 return 1; 685 686 PRINT_PROC("OS language : "); 687 if (nvram[6] < ARRAY_SIZE(languages)) 688 PRINT_PROC("%s\n", languages[nvram[6]]); 689 else 690 PRINT_PROC("%u (undefined)\n", nvram[6]); 691 PRINT_PROC("Keyboard language: "); 692 if (nvram[7] < ARRAY_SIZE(languages)) 693 PRINT_PROC("%s\n", languages[nvram[7]]); 694 else 695 PRINT_PROC("%u (undefined)\n", nvram[7]); 696 PRINT_PROC("Date format : "); 697 PRINT_PROC(dateformat[nvram[8] & 7], 698 nvram[9] ? nvram[9] : '/', nvram[9] ? nvram[9] : '/'); 699 PRINT_PROC(", %dh clock\n", nvram[8] & 16 ? 24 : 12); 700 PRINT_PROC("Boot delay : "); 701 if (nvram[10] == 0) 702 PRINT_PROC("default"); 703 else 704 PRINT_PROC("%ds%s\n", nvram[10], 705 nvram[10] < 8 ? ", no memory test" : ""); 706 707 vmode = (nvram[14] << 8) || nvram[15]; 708 PRINT_PROC("Video mode : %s colors, %d columns, %s %s monitor\n", 709 colors[vmode & 7], 710 vmode & 8 ? 80 : 40, 711 vmode & 16 ? "VGA" : "TV", vmode & 32 ? "PAL" : "NTSC"); 712 PRINT_PROC(" %soverscan, compat. mode %s%s\n", 713 vmode & 64 ? "" : "no ", 714 vmode & 128 ? "on" : "off", 715 vmode & 256 ? 716 (vmode & 16 ? ", line doubling" : ", half screen") : ""); 717 718 return 1; 719 } 720 #endif 721 722 #endif /* MACH == ATARI */ 723 724 MODULE_LICENSE("GPL"); 725 726 EXPORT_SYMBOL(__nvram_read_byte); 727 EXPORT_SYMBOL(nvram_read_byte); 728 EXPORT_SYMBOL(__nvram_write_byte); 729 EXPORT_SYMBOL(nvram_write_byte); 730 EXPORT_SYMBOL(__nvram_check_checksum); 731 EXPORT_SYMBOL(nvram_check_checksum); 732 MODULE_ALIAS_MISCDEV(NVRAM_MINOR); 733