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