arch/powerpc/kernel/nvram_64.c

   1 /*
   2  *  c 2001 PPC 64 Team, IBM Corp
   3  *
   4  *      This program is free software; you can redistribute it and/or
   5  *      modify it under the terms of the GNU General Public License
   6  *      as published by the Free Software Foundation; either version
   7  *      2 of the License, or (at your option) any later version.
   8  *
   9  * /dev/nvram driver for PPC64
  10  *
  11  * This perhaps should live in drivers/char
  12  *
  13  * TODO: Split the /dev/nvram part (that one can use
  14  *       drivers/char/generic_nvram.c) from the arch & partition
  15  *       parsing code.
  16  */
  17
  18 #include <linux/module.h>
  19
  20 #include <linux/types.h>
  21 #include <linux/errno.h>
  22 #include <linux/fs.h>
  23 #include <linux/miscdevice.h>
  24 #include <linux/fcntl.h>
  25 #include <linux/nvram.h>
  26 #include <linux/init.h>
  27 #include <linux/slab.h>
  28 #include <linux/spinlock.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/nvram.h>
  31 #include <asm/rtas.h>
  32 #include <asm/prom.h>
  33 #include <asm/machdep.h>
  34
  35 #undef DEBUG_NVRAM
  36
  37 static int nvram_scan_partitions(void);
  38 static int nvram_setup_partition(void);
  39 static int nvram_create_os_partition(void);
  40 static int nvram_remove_os_partition(void);
  41
  42 static struct nvram_partition * nvram_part;
  43 static long nvram_error_log_index = -1;
  44 static long nvram_error_log_size = 0;
  45
  46 int no_logging = 1;     /* Until we initialize everything,
  47                          * make sure we don't try logging
  48                          * anything */
  49
  50 extern volatile int error_log_cnt;
  51
  52 struct err_log_info {
  53         int error_type;
  54         unsigned int seq_num;
  55 };
  56
  57 static loff_t dev_nvram_llseek(struct file *file, loff_t offset, int origin)
  58 {
  59         int size;
  60
  61         if (ppc_md.nvram_size == NULL)
  62                 return -ENODEV;
  63         size = ppc_md.nvram_size();
  64
  65         switch (origin) {
  66         case 1:
  67                 offset += file->f_pos;
  68                 break;
  69         case 2:
  70                 offset += size;
  71                 break;
  72         }
  73         if (offset < 0)
  74                 return -EINVAL;
  75         file->f_pos = offset;
  76         return file->f_pos;
  77 }
  78
  79
  80 static ssize_t dev_nvram_read(struct file *file, char __user *buf,
  81                           size_t count, loff_t *ppos)
  82 {
  83         ssize_t len;
  84         char *tmp_buffer;
  85         int size;
  86
  87         if (ppc_md.nvram_size == NULL)
  88                 return -ENODEV;
  89         size = ppc_md.nvram_size();
  90
  91         if (!access_ok(VERIFY_WRITE, buf, count))
  92                 return -EFAULT;
  93         if (*ppos >= size)
  94                 return 0;
  95         if (count > size)
  96                 count = size;
  97
  98         tmp_buffer = (char *) kmalloc(count, GFP_KERNEL);
  99         if (!tmp_buffer) {
 100                 printk(KERN_ERR "dev_read_nvram: kmalloc failed\n");
 101                 return -ENOMEM;
 102         }
 103
 104         len = ppc_md.nvram_read(tmp_buffer, count, ppos);
 105         if ((long)len <= 0) {
 106                 kfree(tmp_buffer);
 107                 return len;
 108         }
 109
 110         if (copy_to_user(buf, tmp_buffer, len)) {
 111                 kfree(tmp_buffer);
 112                 return -EFAULT;
 113         }
 114
 115         kfree(tmp_buffer);
 116         return len;
 117
 118 }
 119
 120 static ssize_t dev_nvram_write(struct file *file, const char __user *buf,
 121                            size_t count, loff_t *ppos)
 122 {
 123         ssize_t len;
 124         char * tmp_buffer;
 125         int size;
 126
 127         if (ppc_md.nvram_size == NULL)
 128                 return -ENODEV;
 129         size = ppc_md.nvram_size();
 130
 131         if (!access_ok(VERIFY_READ, buf, count))
 132                 return -EFAULT;
 133         if (*ppos >= size)
 134                 return 0;
 135         if (count > size)
 136                 count = size;
 137
 138         tmp_buffer = (char *) kmalloc(count, GFP_KERNEL);
 139         if (!tmp_buffer) {
 140                 printk(KERN_ERR "dev_nvram_write: kmalloc failed\n");
 141                 return -ENOMEM;
 142         }
 143
 144         if (copy_from_user(tmp_buffer, buf, count)) {
 145                 kfree(tmp_buffer);
 146                 return -EFAULT;
 147         }
 148
 149         len = ppc_md.nvram_write(tmp_buffer, count, ppos);
 150         if ((long)len <= 0) {
 151                 kfree(tmp_buffer);
 152                 return len;
 153         }
 154
 155         kfree(tmp_buffer);
 156         return len;
 157 }
 158
 159 static int dev_nvram_ioctl(struct inode *inode, struct file *file,
 160         unsigned int cmd, unsigned long arg)
 161 {
 162         switch(cmd) {
 163 #ifdef CONFIG_PPC_PMAC
 164         case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
 165                 printk(KERN_WARNING "nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
 166         case IOC_NVRAM_GET_OFFSET: {
 167                 int part, offset;
 168
 169                 if (_machine != PLATFORM_POWERMAC)
 170                         return -EINVAL;
 171                 if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
 172                         return -EFAULT;
 173                 if (part < pmac_nvram_OF || part > pmac_nvram_NR)
 174                         return -EINVAL;
 175                 offset = pmac_get_partition(part);
 176                 if (offset < 0)
 177                         return offset;
 178                 if (copy_to_user((void __user*)arg, &offset, sizeof(offset)) != 0)
 179                         return -EFAULT;
 180                 return 0;
 181         }
 182 #endif /* CONFIG_PPC_PMAC */
 183         }
 184         return -EINVAL;
 185 }
 186
 187 struct file_operations nvram_fops = {
 188         .owner =        THIS_MODULE,
 189         .llseek =       dev_nvram_llseek,
 190         .read =         dev_nvram_read,
 191         .write =        dev_nvram_write,
 192         .ioctl =        dev_nvram_ioctl,
 193 };
 194
 195 static struct miscdevice nvram_dev = {
 196         NVRAM_MINOR,
 197         "nvram",
 198         &nvram_fops
 199 };
 200
 201
 202 #ifdef DEBUG_NVRAM
 203 static void nvram_print_partitions(char * label)
 204 {
 205         struct list_head * p;
 206         struct nvram_partition * tmp_part;
 207
 208         printk(KERN_WARNING "--------%s---------\n", label);
 209         printk(KERN_WARNING "indx\t\tsig\tchks\tlen\tname\n");
 210         list_for_each(p, &nvram_part->partition) {
 211                 tmp_part = list_entry(p, struct nvram_partition, partition);
 212                 printk(KERN_WARNING "%d    \t%02x\t%02x\t%d\t%s\n",
 213                        tmp_part->index, tmp_part->header.signature,
 214                        tmp_part->header.checksum, tmp_part->header.length,
 215                        tmp_part->header.name);
 216         }
 217 }
 218 #endif
 219
 220
 221 static int nvram_write_header(struct nvram_partition * part)
 222 {
 223         loff_t tmp_index;
 224         int rc;
 225
 226         tmp_index = part->index;
 227         rc = ppc_md.nvram_write((char *)&part->header, NVRAM_HEADER_LEN, &tmp_index);
 228
 229         return rc;
 230 }
 231
 232
 233 static unsigned char nvram_checksum(struct nvram_header *p)
 234 {
 235         unsigned int c_sum, c_sum2;
 236         unsigned short *sp = (unsigned short *)p->name; /* assume 6 shorts */
 237         c_sum = p->signature + p->length + sp[0] + sp[1] + sp[2] + sp[3] + sp[4] + sp[5];
 238
 239         /* The sum may have spilled into the 3rd byte.  Fold it back. */
 240         c_sum = ((c_sum & 0xffff) + (c_sum >> 16)) & 0xffff;
 241         /* The sum cannot exceed 2 bytes.  Fold it into a checksum */
 242         c_sum2 = (c_sum >> 8) + (c_sum << 8);
 243         c_sum = ((c_sum + c_sum2) >> 8) & 0xff;
 244         return c_sum;
 245 }
 246
 247
 248 /*
 249  * Find an nvram partition, sig can be 0 for any
 250  * partition or name can be NULL for any name, else
 251  * tries to match both
 252  */
 253 struct nvram_partition *nvram_find_partition(int sig, const char *name)
 254 {
 255         struct nvram_partition * part;
 256         struct list_head * p;
 257
 258         list_for_each(p, &nvram_part->partition) {
 259                 part = list_entry(p, struct nvram_partition, partition);
 260
 261                 if (sig && part->header.signature != sig)
 262                         continue;
 263                 if (name && 0 != strncmp(name, part->header.name, 12))
 264                         continue;
 265                 return part;
 266         }
 267         return NULL;
 268 }
 269 EXPORT_SYMBOL(nvram_find_partition);
 270
 271
 272 static int nvram_remove_os_partition(void)
 273 {
 274         struct list_head *i;
 275         struct list_head *j;
 276         struct nvram_partition * part;
 277         struct nvram_partition * cur_part;
 278         int rc;
 279
 280         list_for_each(i, &nvram_part->partition) {
 281                 part = list_entry(i, struct nvram_partition, partition);
 282                 if (part->header.signature != NVRAM_SIG_OS)
 283                         continue;
 284
 285                 /* Make os partition a free partition */
 286                 part->header.signature = NVRAM_SIG_FREE;
 287                 sprintf(part->header.name, "wwwwwwwwwwww");
 288                 part->header.checksum = nvram_checksum(&part->header);
 289
 290                 /* Merge contiguous free partitions backwards */
 291                 list_for_each_prev(j, &part->partition) {
 292                         cur_part = list_entry(j, struct nvram_partition, partition);
 293                         if (cur_part == nvram_part || cur_part->header.signature != NVRAM_SIG_FREE) {
 294                                 break;
 295                         }
 296
 297                         part->header.length += cur_part->header.length;
 298                         part->header.checksum = nvram_checksum(&part->header);
 299                         part->index = cur_part->index;
 300
 301                         list_del(&cur_part->partition);
 302                         kfree(cur_part);
 303                         j = &part->partition; /* fixup our loop */
 304                 }
 305
 306                 /* Merge contiguous free partitions forwards */
 307                 list_for_each(j, &part->partition) {
 308                         cur_part = list_entry(j, struct nvram_partition, partition);
 309                         if (cur_part == nvram_part || cur_part->header.signature != NVRAM_SIG_FREE) {
 310                                 break;
 311                         }
 312
 313                         part->header.length += cur_part->header.length;
 314                         part->header.checksum = nvram_checksum(&part->header);
 315
 316                         list_del(&cur_part->partition);
 317                         kfree(cur_part);
 318                         j = &part->partition; /* fixup our loop */
 319                 }
 320
 321                 rc = nvram_write_header(part);
 322                 if (rc <= 0) {
 323                         printk(KERN_ERR "nvram_remove_os_partition: nvram_write failed (%d)\n", rc);
 324                         return rc;
 325                 }
 326
 327         }
 328
 329         return 0;
 330 }
 331
 332 /* nvram_create_os_partition
 333  *
 334  * Create a OS linux partition to buffer error logs.
 335  * Will create a partition starting at the first free
 336  * space found if space has enough room.
 337  */
 338 static int nvram_create_os_partition(void)
 339 {
 340         struct nvram_partition *part;
 341         struct nvram_partition *new_part;
 342         struct nvram_partition *free_part = NULL;
 343         int seq_init[2] = { 0, 0 };
 344         loff_t tmp_index;
 345         long size = 0;
 346         int rc;
 347
 348         /* Find a free partition that will give us the maximum needed size
 349            If can't find one that will give us the minimum size needed */
 350         list_for_each_entry(part, &nvram_part->partition, partition) {
 351                 if (part->header.signature != NVRAM_SIG_FREE)
 352                         continue;
 353
 354                 if (part->header.length >= NVRAM_MAX_REQ) {
 355                         size = NVRAM_MAX_REQ;
 356                         free_part = part;
 357                         break;
 358                 }
 359                 if (!size && part->header.length >= NVRAM_MIN_REQ) {
 360                         size = NVRAM_MIN_REQ;
 361                         free_part = part;
 362                 }
 363         }
 364         if (!size)
 365                 return -ENOSPC;
 366
 367         /* Create our OS partition */
 368         new_part = kmalloc(sizeof(*new_part), GFP_KERNEL);
 369         if (!new_part) {
 370                 printk(KERN_ERR "nvram_create_os_partition: kmalloc failed\n");
 371                 return -ENOMEM;
 372         }
 373
 374         new_part->index = free_part->index;
 375         new_part->header.signature = NVRAM_SIG_OS;
 376         new_part->header.length = size;
 377         strcpy(new_part->header.name, "ppc64,linux");
 378         new_part->header.checksum = nvram_checksum(&new_part->header);
 379
 380         rc = nvram_write_header(new_part);
 381         if (rc <= 0) {
 382                 printk(KERN_ERR "nvram_create_os_partition: nvram_write_header \
 383                                 failed (%d)\n", rc);
 384                 return rc;
 385         }
 386
 387         /* make sure and initialize to zero the sequence number and the error
 388            type logged */
 389         tmp_index = new_part->index + NVRAM_HEADER_LEN;
 390         rc = ppc_md.nvram_write((char *)&seq_init, sizeof(seq_init), &tmp_index);
 391         if (rc <= 0) {
 392                 printk(KERN_ERR "nvram_create_os_partition: nvram_write "
 393                                 "failed (%d)\n", rc);
 394                 return rc;
 395         }
 396
 397         nvram_error_log_index = new_part->index + NVRAM_HEADER_LEN;
 398         nvram_error_log_size = ((part->header.length - 1) *
 399                                 NVRAM_BLOCK_LEN) - sizeof(struct err_log_info);
 400
 401         list_add_tail(&new_part->partition, &free_part->partition);
 402
 403         if (free_part->header.length <= size) {
 404                 list_del(&free_part->partition);
 405                 kfree(free_part);
 406                 return 0;
 407         }
 408
 409         /* Adjust the partition we stole the space from */
 410         free_part->index += size * NVRAM_BLOCK_LEN;
 411         free_part->header.length -= size;
 412         free_part->header.checksum = nvram_checksum(&free_part->header);
 413
 414         rc = nvram_write_header(free_part);
 415         if (rc <= 0) {
 416                 printk(KERN_ERR "nvram_create_os_partition: nvram_write_header "
 417                        "failed (%d)\n", rc);
 418                 return rc;
 419         }
 420
 421         return 0;
 422 }
 423
 424
 425 /* nvram_setup_partition
 426  *
 427  * This will setup the partition we need for buffering the
 428  * error logs and cleanup partitions if needed.
 429  *
 430  * The general strategy is the following:
 431  * 1.) If there is ppc64,linux partition large enough then use it.
 432  * 2.) If there is not a ppc64,linux partition large enough, search
 433  * for a free partition that is large enough.
 434  * 3.) If there is not a free partition large enough remove
 435  * _all_ OS partitions and consolidate the space.
 436  * 4.) Will first try getting a chunk that will satisfy the maximum
 437  * error log size (NVRAM_MAX_REQ).
 438  * 5.) If the max chunk cannot be allocated then try finding a chunk
 439  * that will satisfy the minum needed (NVRAM_MIN_REQ).
 440  */
 441 static int nvram_setup_partition(void)
 442 {
 443         struct list_head * p;
 444         struct nvram_partition * part;
 445         int rc;
 446
 447         /* For now, we don't do any of this on pmac, until I
 448          * have figured out if it's worth killing some unused stuffs
 449          * in our nvram, as Apple defined partitions use pretty much
 450          * all of the space
 451          */
 452         if (_machine == PLATFORM_POWERMAC)
 453                 return -ENOSPC;
 454
 455         /* see if we have an OS partition that meets our needs.
 456            will try getting the max we need.  If not we'll delete
 457            partitions and try again. */
 458         list_for_each(p, &nvram_part->partition) {
 459                 part = list_entry(p, struct nvram_partition, partition);
 460                 if (part->header.signature != NVRAM_SIG_OS)
 461                         continue;
 462
 463                 if (strcmp(part->header.name, "ppc64,linux"))
 464                         continue;
 465
 466                 if (part->header.length >= NVRAM_MIN_REQ) {
 467                         /* found our partition */
 468                         nvram_error_log_index = part->index + NVRAM_HEADER_LEN;
 469                         nvram_error_log_size = ((part->header.length - 1) *
 470                                                 NVRAM_BLOCK_LEN) - sizeof(struct err_log_info);
 471                         return 0;
 472                 }
 473         }
 474
 475         /* try creating a partition with the free space we have */
 476         rc = nvram_create_os_partition();
 477         if (!rc) {
 478                 return 0;
 479         }
 480
 481         /* need to free up some space */
 482         rc = nvram_remove_os_partition();
 483         if (rc) {
 484                 return rc;
 485         }
 486
 487         /* create a partition in this new space */
 488         rc = nvram_create_os_partition();
 489         if (rc) {
 490                 printk(KERN_ERR "nvram_create_os_partition: Could not find a "
 491                        "NVRAM partition large enough\n");
 492                 return rc;
 493         }
 494
 495         return 0;
 496 }
 497
 498
 499 static int nvram_scan_partitions(void)
 500 {
 501         loff_t cur_index = 0;
 502         struct nvram_header phead;
 503         struct nvram_partition * tmp_part;
 504         unsigned char c_sum;
 505         char * header;
 506         int total_size;
 507         int err;
 508
 509         if (ppc_md.nvram_size == NULL)
 510                 return -ENODEV;
 511         total_size = ppc_md.nvram_size();
 512
 513         header = (char *) kmalloc(NVRAM_HEADER_LEN, GFP_KERNEL);
 514         if (!header) {
 515                 printk(KERN_ERR "nvram_scan_partitions: Failed kmalloc\n");
 516                 return -ENOMEM;
 517         }
 518
 519         while (cur_index < total_size) {
 520
 521                 err = ppc_md.nvram_read(header, NVRAM_HEADER_LEN, &cur_index);
 522                 if (err != NVRAM_HEADER_LEN) {
 523                         printk(KERN_ERR "nvram_scan_partitions: Error parsing "
 524                                "nvram partitions\n");
 525                         goto out;
 526                 }
 527
 528                 cur_index -= NVRAM_HEADER_LEN; /* nvram_read will advance us */
 529
 530                 memcpy(&phead, header, NVRAM_HEADER_LEN);
 531
 532                 err = 0;
 533                 c_sum = nvram_checksum(&phead);
 534                 if (c_sum != phead.checksum) {
 535                         printk(KERN_WARNING "WARNING: nvram partition checksum"
 536                                " was %02x, should be %02x!\n",
 537                                phead.checksum, c_sum);
 538                         printk(KERN_WARNING "Terminating nvram partition scan\n");
 539                         goto out;
 540                 }
 541                 if (!phead.length) {
 542                         printk(KERN_WARNING "WARNING: nvram corruption "
 543                                "detected: 0-length partition\n");
 544                         goto out;
 545                 }
 546                 tmp_part = (struct nvram_partition *)
 547                         kmalloc(sizeof(struct nvram_partition), GFP_KERNEL);
 548                 err = -ENOMEM;
 549                 if (!tmp_part) {
 550                         printk(KERN_ERR "nvram_scan_partitions: kmalloc failed\n");
 551                         goto out;
 552                 }
 553
 554                 memcpy(&tmp_part->header, &phead, NVRAM_HEADER_LEN);
 555                 tmp_part->index = cur_index;
 556                 list_add_tail(&tmp_part->partition, &nvram_part->partition);
 557
 558                 cur_index += phead.length * NVRAM_BLOCK_LEN;
 559         }
 560         err = 0;
 561
 562  out:
 563         kfree(header);
 564         return err;
 565 }
 566
 567 static int __init nvram_init(void)
 568 {
 569         int error;
 570         int rc;
 571
 572         if (ppc_md.nvram_size == NULL || ppc_md.nvram_size() <= 0)
 573                 return  -ENODEV;
 574
 575         rc = misc_register(&nvram_dev);
 576         if (rc != 0) {
 577                 printk(KERN_ERR "nvram_init: failed to register device\n");
 578                 return rc;
 579         }
 580
 581         /* initialize our anchor for the nvram partition list */
 582         nvram_part = (struct nvram_partition *) kmalloc(sizeof(struct nvram_partition), GFP_KERNEL);
 583         if (!nvram_part) {
 584                 printk(KERN_ERR "nvram_init: Failed kmalloc\n");
 585                 return -ENOMEM;
 586         }
 587         INIT_LIST_HEAD(&nvram_part->partition);
 588
 589         /* Get all the NVRAM partitions */
 590         error = nvram_scan_partitions();
 591         if (error) {
 592                 printk(KERN_ERR "nvram_init: Failed nvram_scan_partitions\n");
 593                 return error;
 594         }
 595
 596         if(nvram_setup_partition())
 597                 printk(KERN_WARNING "nvram_init: Could not find nvram partition"
 598                        " for nvram buffered error logging.\n");
 599
 600 #ifdef DEBUG_NVRAM
 601         nvram_print_partitions("NVRAM Partitions");
 602 #endif
 603
 604         return rc;
 605 }
 606
 607 void __exit nvram_cleanup(void)
 608 {
 609         misc_deregister( &nvram_dev );
 610 }
 611
 612
 613 #ifdef CONFIG_PPC_PSERIES
 614
 615 /* nvram_write_error_log
 616  *
 617  * We need to buffer the error logs into nvram to ensure that we have
 618  * the failure information to decode.  If we have a severe error there
 619  * is no way to guarantee that the OS or the machine is in a state to
 620  * get back to user land and write the error to disk.  For example if
 621  * the SCSI device driver causes a Machine Check by writing to a bad
 622  * IO address, there is no way of guaranteeing that the device driver
 623  * is in any state that is would also be able to write the error data
 624  * captured to disk, thus we buffer it in NVRAM for analysis on the
 625  * next boot.
 626  *
 627  * In NVRAM the partition containing the error log buffer will looks like:
 628  * Header (in bytes):
 629  * +-----------+----------+--------+------------+------------------+
 630  * | signature | checksum | length | name       | data             |
 631  * |0          |1         |2      3|4         15|16        length-1|
 632  * +-----------+----------+--------+------------+------------------+
 633  *
 634  * The 'data' section would look like (in bytes):
 635  * +--------------+------------+-----------------------------------+
 636  * | event_logged | sequence # | error log                         |
 637  * |0            3|4          7|8            nvram_error_log_size-1|
 638  * +--------------+------------+-----------------------------------+
 639  *
 640  * event_logged: 0 if event has not been logged to syslog, 1 if it has
 641  * sequence #: The unique sequence # for each event. (until it wraps)
 642  * error log: The error log from event_scan
 643  */
 644 int nvram_write_error_log(char * buff, int length, unsigned int err_type)
 645 {
 646         int rc;
 647         loff_t tmp_index;
 648         struct err_log_info info;
 649
 650         if (no_logging) {
 651                 return -EPERM;
 652         }
 653
 654         if (nvram_error_log_index == -1) {
 655                 return -ESPIPE;
 656         }
 657
 658         if (length > nvram_error_log_size) {
 659                 length = nvram_error_log_size;
 660         }
 661
 662         info.error_type = err_type;
 663         info.seq_num = error_log_cnt;
 664
 665         tmp_index = nvram_error_log_index;
 666
 667         rc = ppc_md.nvram_write((char *)&info, sizeof(struct err_log_info), &tmp_index);
 668         if (rc <= 0) {
 669                 printk(KERN_ERR "nvram_write_error_log: Failed nvram_write (%d)\n", rc);
 670                 return rc;
 671         }
 672
 673         rc = ppc_md.nvram_write(buff, length, &tmp_index);
 674         if (rc <= 0) {
 675                 printk(KERN_ERR "nvram_write_error_log: Failed nvram_write (%d)\n", rc);
 676                 return rc;
 677         }
 678
 679         return 0;
 680 }
 681
 682 /* nvram_read_error_log
 683  *
 684  * Reads nvram for error log for at most 'length'
 685  */
 686 int nvram_read_error_log(char * buff, int length, unsigned int * err_type)
 687 {
 688         int rc;
 689         loff_t tmp_index;
 690         struct err_log_info info;
 691
 692         if (nvram_error_log_index == -1)
 693                 return -1;
 694
 695         if (length > nvram_error_log_size)
 696                 length = nvram_error_log_size;
 697
 698         tmp_index = nvram_error_log_index;
 699
 700         rc = ppc_md.nvram_read((char *)&info, sizeof(struct err_log_info), &tmp_index);
 701         if (rc <= 0) {
 702                 printk(KERN_ERR "nvram_read_error_log: Failed nvram_read (%d)\n", rc);
 703                 return rc;
 704         }
 705
 706         rc = ppc_md.nvram_read(buff, length, &tmp_index);
 707         if (rc <= 0) {
 708                 printk(KERN_ERR "nvram_read_error_log: Failed nvram_read (%d)\n", rc);
 709                 return rc;
 710         }
 711
 712         error_log_cnt = info.seq_num;
 713         *err_type = info.error_type;
 714
 715         return 0;
 716 }
 717
 718 /* This doesn't actually zero anything, but it sets the event_logged
 719  * word to tell that this event is safely in syslog.
 720  */
 721 int nvram_clear_error_log(void)
 722 {
 723         loff_t tmp_index;
 724         int clear_word = ERR_FLAG_ALREADY_LOGGED;
 725         int rc;
 726
 727         tmp_index = nvram_error_log_index;
 728
 729         rc = ppc_md.nvram_write((char *)&clear_word, sizeof(int), &tmp_index);
 730         if (rc <= 0) {
 731                 printk(KERN_ERR "nvram_clear_error_log: Failed nvram_write (%d)\n", rc);
 732                 return rc;
 733         }
 734
 735         return 0;
 736 }
 737
 738 #endif /* CONFIG_PPC_PSERIES */
 739
 740 module_init(nvram_init);
 741 module_exit(nvram_cleanup);
 742 MODULE_LICENSE("GPL");