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 #define NVRAM_HEADER_LEN        sizeof(struct nvram_header)
  38 #define NVRAM_BLOCK_LEN         NVRAM_HEADER_LEN
  39 #define NVRAM_MAX_REQ           2079
  40 #define NVRAM_MIN_REQ           1055
  41
  42 /* If change this size, then change the size of NVNAME_LEN */
  43 struct nvram_header {
  44         unsigned char signature;
  45         unsigned char checksum;
  46         unsigned short length;
  47         char name[12];
  48 };
  49
  50 struct nvram_partition {
  51         struct list_head partition;
  52         struct nvram_header header;
  53         unsigned int index;
  54 };
  55
  56 static struct nvram_partition * nvram_part;
  57 static long nvram_error_log_index = -1;
  58 static long nvram_error_log_size = 0;
  59
  60 struct err_log_info {
  61         int error_type;
  62         unsigned int seq_num;
  63 };
  64
  65 static loff_t dev_nvram_llseek(struct file *file, loff_t offset, int origin)
  66 {
  67         int size;
  68
  69         if (ppc_md.nvram_size == NULL)
  70                 return -ENODEV;
  71         size = ppc_md.nvram_size();
  72
  73         switch (origin) {
  74         case 1:
  75                 offset += file->f_pos;
  76                 break;
  77         case 2:
  78                 offset += size;
  79                 break;
  80         }
  81         if (offset < 0)
  82                 return -EINVAL;
  83         file->f_pos = offset;
  84         return file->f_pos;
  85 }
  86
  87
  88 static ssize_t dev_nvram_read(struct file *file, char __user *buf,
  89                           size_t count, loff_t *ppos)
  90 {
  91         ssize_t ret;
  92         char *tmp = NULL;
  93         ssize_t size;
  94
  95         ret = -ENODEV;
  96         if (!ppc_md.nvram_size)
  97                 goto out;
  98
  99         ret = 0;
 100         size = ppc_md.nvram_size();
 101         if (*ppos >= size || size < 0)
 102                 goto out;
 103
 104         count = min_t(size_t, count, size - *ppos);
 105         count = min(count, PAGE_SIZE);
 106
 107         ret = -ENOMEM;
 108         tmp = kmalloc(count, GFP_KERNEL);
 109         if (!tmp)
 110                 goto out;
 111
 112         ret = ppc_md.nvram_read(tmp, count, ppos);
 113         if (ret <= 0)
 114                 goto out;
 115
 116         if (copy_to_user(buf, tmp, ret))
 117                 ret = -EFAULT;
 118
 119 out:
 120         kfree(tmp);
 121         return ret;
 122
 123 }
 124
 125 static ssize_t dev_nvram_write(struct file *file, const char __user *buf,
 126                           size_t count, loff_t *ppos)
 127 {
 128         ssize_t ret;
 129         char *tmp = NULL;
 130         ssize_t size;
 131
 132         ret = -ENODEV;
 133         if (!ppc_md.nvram_size)
 134                 goto out;
 135
 136         ret = 0;
 137         size = ppc_md.nvram_size();
 138         if (*ppos >= size || size < 0)
 139                 goto out;
 140
 141         count = min_t(size_t, count, size - *ppos);
 142         count = min(count, PAGE_SIZE);
 143
 144         ret = -ENOMEM;
 145         tmp = kmalloc(count, GFP_KERNEL);
 146         if (!tmp)
 147                 goto out;
 148
 149         ret = -EFAULT;
 150         if (copy_from_user(tmp, buf, count))
 151                 goto out;
 152
 153         ret = ppc_md.nvram_write(tmp, count, ppos);
 154
 155 out:
 156         kfree(tmp);
 157         return ret;
 158
 159 }
 160
 161 static long dev_nvram_ioctl(struct file *file, unsigned int cmd,
 162                             unsigned long arg)
 163 {
 164         switch(cmd) {
 165 #ifdef CONFIG_PPC_PMAC
 166         case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
 167                 printk(KERN_WARNING "nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
 168         case IOC_NVRAM_GET_OFFSET: {
 169                 int part, offset;
 170
 171                 if (!machine_is(powermac))
 172                         return -EINVAL;
 173                 if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
 174                         return -EFAULT;
 175                 if (part < pmac_nvram_OF || part > pmac_nvram_NR)
 176                         return -EINVAL;
 177                 offset = pmac_get_partition(part);
 178                 if (offset < 0)
 179                         return offset;
 180                 if (copy_to_user((void __user*)arg, &offset, sizeof(offset)) != 0)
 181                         return -EFAULT;
 182                 return 0;
 183         }
 184 #endif /* CONFIG_PPC_PMAC */
 185         default:
 186                 return -EINVAL;
 187         }
 188 }
 189
 190 const struct file_operations nvram_fops = {
 191         .owner          = THIS_MODULE,
 192         .llseek         = dev_nvram_llseek,
 193         .read           = dev_nvram_read,
 194         .write          = dev_nvram_write,
 195         .unlocked_ioctl = dev_nvram_ioctl,
 196 };
 197
 198 static struct miscdevice nvram_dev = {
 199         NVRAM_MINOR,
 200         "nvram",
 201         &nvram_fops
 202 };
 203
 204
 205 #ifdef DEBUG_NVRAM
 206 static void __init nvram_print_partitions(char * label)
 207 {
 208         struct list_head * p;
 209         struct nvram_partition * tmp_part;
 210
 211         printk(KERN_WARNING "--------%s---------\n", label);
 212         printk(KERN_WARNING "indx\t\tsig\tchks\tlen\tname\n");
 213         list_for_each(p, &nvram_part->partition) {
 214                 tmp_part = list_entry(p, struct nvram_partition, partition);
 215                 printk(KERN_WARNING "%4d    \t%02x\t%02x\t%d\t%s\n",
 216                        tmp_part->index, tmp_part->header.signature,
 217                        tmp_part->header.checksum, tmp_part->header.length,
 218                        tmp_part->header.name);
 219         }
 220 }
 221 #endif
 222
 223
 224 static int __init nvram_write_header(struct nvram_partition * part)
 225 {
 226         loff_t tmp_index;
 227         int rc;
 228
 229         tmp_index = part->index;
 230         rc = ppc_md.nvram_write((char *)&part->header, NVRAM_HEADER_LEN, &tmp_index);
 231
 232         return rc;
 233 }
 234
 235
 236 static unsigned char __init nvram_checksum(struct nvram_header *p)
 237 {
 238         unsigned int c_sum, c_sum2;
 239         unsigned short *sp = (unsigned short *)p->name; /* assume 6 shorts */
 240         c_sum = p->signature + p->length + sp[0] + sp[1] + sp[2] + sp[3] + sp[4] + sp[5];
 241
 242         /* The sum may have spilled into the 3rd byte.  Fold it back. */
 243         c_sum = ((c_sum & 0xffff) + (c_sum >> 16)) & 0xffff;
 244         /* The sum cannot exceed 2 bytes.  Fold it into a checksum */
 245         c_sum2 = (c_sum >> 8) + (c_sum << 8);
 246         c_sum = ((c_sum + c_sum2) >> 8) & 0xff;
 247         return c_sum;
 248 }
 249
 250 static int __init nvram_remove_os_partition(void)
 251 {
 252         struct list_head *i;
 253         struct list_head *j;
 254         struct nvram_partition * part;
 255         struct nvram_partition * cur_part;
 256         int rc;
 257
 258         list_for_each(i, &nvram_part->partition) {
 259                 part = list_entry(i, struct nvram_partition, partition);
 260                 if (part->header.signature != NVRAM_SIG_OS)
 261                         continue;
 262
 263                 /* Make os partition a free partition */
 264                 part->header.signature = NVRAM_SIG_FREE;
 265                 sprintf(part->header.name, "wwwwwwwwwwww");
 266                 part->header.checksum = nvram_checksum(&part->header);
 267
 268                 /* Merge contiguous free partitions backwards */
 269                 list_for_each_prev(j, &part->partition) {
 270                         cur_part = list_entry(j, struct nvram_partition, partition);
 271                         if (cur_part == nvram_part || cur_part->header.signature != NVRAM_SIG_FREE) {
 272                                 break;
 273                         }
 274
 275                         part->header.length += cur_part->header.length;
 276                         part->header.checksum = nvram_checksum(&part->header);
 277                         part->index = cur_part->index;
 278
 279                         list_del(&cur_part->partition);
 280                         kfree(cur_part);
 281                         j = &part->partition; /* fixup our loop */
 282                 }
 283
 284                 /* Merge contiguous free partitions forwards */
 285                 list_for_each(j, &part->partition) {
 286                         cur_part = list_entry(j, struct nvram_partition, partition);
 287                         if (cur_part == nvram_part || cur_part->header.signature != NVRAM_SIG_FREE) {
 288                                 break;
 289                         }
 290
 291                         part->header.length += cur_part->header.length;
 292                         part->header.checksum = nvram_checksum(&part->header);
 293
 294                         list_del(&cur_part->partition);
 295                         kfree(cur_part);
 296                         j = &part->partition; /* fixup our loop */
 297                 }
 298
 299                 rc = nvram_write_header(part);
 300                 if (rc <= 0) {
 301                         printk(KERN_ERR "nvram_remove_os_partition: nvram_write failed (%d)\n", rc);
 302                         return rc;
 303                 }
 304
 305         }
 306
 307         return 0;
 308 }
 309
 310 /**
 311  * nvram_create_partition - Create a partition in nvram
 312  * @name: name of the partition to create
 313  * @sig: signature of the partition to create
 314  * @req_size: size of data to allocate in bytes
 315  * @min_size: minimum acceptable size (0 means req_size)
 316  */
 317 static int __init nvram_create_partition(const char *name, int sig,
 318                                          int req_size, int min_size)
 319 {
 320         struct nvram_partition *part;
 321         struct nvram_partition *new_part;
 322         struct nvram_partition *free_part = NULL;
 323         int seq_init[2] = { 0, 0 };
 324         loff_t tmp_index;
 325         long size = 0;
 326         int rc;
 327
 328         /* Convert sizes from bytes to blocks */
 329         req_size = _ALIGN_UP(req_size, NVRAM_BLOCK_LEN) / NVRAM_BLOCK_LEN;
 330         min_size = _ALIGN_UP(min_size, NVRAM_BLOCK_LEN) / NVRAM_BLOCK_LEN;
 331
 332         /* If no minimum size specified, make it the same as the
 333          * requested size
 334          */
 335         if (min_size == 0)
 336                 min_size = req_size;
 337
 338         /* Now add one block to each for the header */
 339         req_size += 1;
 340         min_size += 1;
 341
 342         /* Find a free partition that will give us the maximum needed size
 343            If can't find one that will give us the minimum size needed */
 344         list_for_each_entry(part, &nvram_part->partition, partition) {
 345                 if (part->header.signature != NVRAM_SIG_FREE)
 346                         continue;
 347
 348                 if (part->header.length >= req_size) {
 349                         size = req_size;
 350                         free_part = part;
 351                         break;
 352                 }
 353                 if (part->header.length > size &&
 354                     part->header.length >= min_size) {
 355                         size = part->header.length;
 356                         free_part = part;
 357                 }
 358         }
 359         if (!size)
 360                 return -ENOSPC;
 361
 362         /* Create our OS partition */
 363         new_part = kmalloc(sizeof(*new_part), GFP_KERNEL);
 364         if (!new_part) {
 365                 printk(KERN_ERR "nvram_create_os_partition: kmalloc failed\n");
 366                 return -ENOMEM;
 367         }
 368
 369         new_part->index = free_part->index;
 370         new_part->header.signature = sig;
 371         new_part->header.length = size;
 372         strncpy(new_part->header.name, name, 12);
 373         new_part->header.checksum = nvram_checksum(&new_part->header);
 374
 375         rc = nvram_write_header(new_part);
 376         if (rc <= 0) {
 377                 printk(KERN_ERR "nvram_create_os_partition: nvram_write_header "
 378                                 "failed (%d)\n", rc);
 379                 return rc;
 380         }
 381
 382         /* make sure and initialize to zero the sequence number and the error
 383            type logged */
 384         tmp_index = new_part->index + NVRAM_HEADER_LEN;
 385         rc = ppc_md.nvram_write((char *)&seq_init, sizeof(seq_init), &tmp_index);
 386         if (rc <= 0) {
 387                 printk(KERN_ERR "nvram_create_os_partition: nvram_write "
 388                        "failed (%d)\n", rc);
 389                 return rc;
 390         }
 391
 392         nvram_error_log_index = new_part->index + NVRAM_HEADER_LEN;
 393         nvram_error_log_size = ((part->header.length - 1) *
 394                                 NVRAM_BLOCK_LEN) - sizeof(struct err_log_info);
 395
 396         list_add_tail(&new_part->partition, &free_part->partition);
 397
 398         if (free_part->header.length <= size) {
 399                 list_del(&free_part->partition);
 400                 kfree(free_part);
 401                 return 0;
 402         }
 403
 404         /* Adjust the partition we stole the space from */
 405         free_part->index += size * NVRAM_BLOCK_LEN;
 406         free_part->header.length -= size;
 407         free_part->header.checksum = nvram_checksum(&free_part->header);
 408
 409         rc = nvram_write_header(free_part);
 410         if (rc <= 0) {
 411                 printk(KERN_ERR "nvram_create_os_partition: nvram_write_header "
 412                        "failed (%d)\n", rc);
 413                 return rc;
 414         }
 415
 416         return 0;
 417 }
 418
 419
 420 /* nvram_setup_partition
 421  *
 422  * This will setup the partition we need for buffering the
 423  * error logs and cleanup partitions if needed.
 424  *
 425  * The general strategy is the following:
 426  * 1.) If there is ppc64,linux partition large enough then use it.
 427  * 2.) If there is not a ppc64,linux partition large enough, search
 428  * for a free partition that is large enough.
 429  * 3.) If there is not a free partition large enough remove
 430  * _all_ OS partitions and consolidate the space.
 431  * 4.) Will first try getting a chunk that will satisfy the maximum
 432  * error log size (NVRAM_MAX_REQ).
 433  * 5.) If the max chunk cannot be allocated then try finding a chunk
 434  * that will satisfy the minum needed (NVRAM_MIN_REQ).
 435  */
 436 static int __init nvram_setup_partition(void)
 437 {
 438         struct list_head * p;
 439         struct nvram_partition * part;
 440         int rc;
 441
 442         /* For now, we don't do any of this on pmac, until I
 443          * have figured out if it's worth killing some unused stuffs
 444          * in our nvram, as Apple defined partitions use pretty much
 445          * all of the space
 446          */
 447         if (machine_is(powermac))
 448                 return -ENOSPC;
 449
 450         /* see if we have an OS partition that meets our needs.
 451            will try getting the max we need.  If not we'll delete
 452            partitions and try again. */
 453         list_for_each(p, &nvram_part->partition) {
 454                 part = list_entry(p, struct nvram_partition, partition);
 455                 if (part->header.signature != NVRAM_SIG_OS)
 456                         continue;
 457
 458                 if (strcmp(part->header.name, "ppc64,linux"))
 459                         continue;
 460
 461                 if ((part->header.length - 1) * NVRAM_BLOCK_LEN >= NVRAM_MIN_REQ) {
 462                         /* found our partition */
 463                         nvram_error_log_index = part->index + NVRAM_HEADER_LEN;
 464                         nvram_error_log_size = ((part->header.length - 1) *
 465                                                 NVRAM_BLOCK_LEN) - sizeof(struct err_log_info);
 466                         return 0;
 467                 }
 468         }
 469
 470         /* try creating a partition with the free space we have */
 471         rc =    nvram_create_partition("ppc64,linux", NVRAM_SIG_OS,
 472                                        NVRAM_MAX_REQ, NVRAM_MIN_REQ);
 473         if (!rc)
 474                 return 0;
 475
 476         /* need to free up some space */
 477         rc = nvram_remove_os_partition();
 478         if (rc) {
 479                 return rc;
 480         }
 481
 482         /* create a partition in this new space */
 483         rc =    nvram_create_partition("ppc64,linux", NVRAM_SIG_OS,
 484                                        NVRAM_MAX_REQ, NVRAM_MIN_REQ);
 485         if (rc) {
 486                 printk(KERN_ERR "nvram_create_partition: Could not find a "
 487                        "NVRAM partition large enough\n");
 488                 return rc;
 489         }
 490
 491         return 0;
 492 }
 493
 494
 495 static int __init nvram_scan_partitions(void)
 496 {
 497         loff_t cur_index = 0;
 498         struct nvram_header phead;
 499         struct nvram_partition * tmp_part;
 500         unsigned char c_sum;
 501         char * header;
 502         int total_size;
 503         int err;
 504
 505         if (ppc_md.nvram_size == NULL)
 506                 return -ENODEV;
 507         total_size = ppc_md.nvram_size();
 508
 509         header = kmalloc(NVRAM_HEADER_LEN, GFP_KERNEL);
 510         if (!header) {
 511                 printk(KERN_ERR "nvram_scan_partitions: Failed kmalloc\n");
 512                 return -ENOMEM;
 513         }
 514
 515         while (cur_index < total_size) {
 516
 517                 err = ppc_md.nvram_read(header, NVRAM_HEADER_LEN, &cur_index);
 518                 if (err != NVRAM_HEADER_LEN) {
 519                         printk(KERN_ERR "nvram_scan_partitions: Error parsing "
 520                                "nvram partitions\n");
 521                         goto out;
 522                 }
 523
 524                 cur_index -= NVRAM_HEADER_LEN; /* nvram_read will advance us */
 525
 526                 memcpy(&phead, header, NVRAM_HEADER_LEN);
 527
 528                 err = 0;
 529                 c_sum = nvram_checksum(&phead);
 530                 if (c_sum != phead.checksum) {
 531                         printk(KERN_WARNING "WARNING: nvram partition checksum"
 532                                " was %02x, should be %02x!\n",
 533                                phead.checksum, c_sum);
 534                         printk(KERN_WARNING "Terminating nvram partition scan\n");
 535                         goto out;
 536                 }
 537                 if (!phead.length) {
 538                         printk(KERN_WARNING "WARNING: nvram corruption "
 539                                "detected: 0-length partition\n");
 540                         goto out;
 541                 }
 542                 tmp_part = (struct nvram_partition *)
 543                         kmalloc(sizeof(struct nvram_partition), GFP_KERNEL);
 544                 err = -ENOMEM;
 545                 if (!tmp_part) {
 546                         printk(KERN_ERR "nvram_scan_partitions: kmalloc failed\n");
 547                         goto out;
 548                 }
 549
 550                 memcpy(&tmp_part->header, &phead, NVRAM_HEADER_LEN);
 551                 tmp_part->index = cur_index;
 552                 list_add_tail(&tmp_part->partition, &nvram_part->partition);
 553
 554                 cur_index += phead.length * NVRAM_BLOCK_LEN;
 555         }
 556         err = 0;
 557
 558  out:
 559         kfree(header);
 560         return err;
 561 }
 562
 563 static int __init nvram_init(void)
 564 {
 565         int error;
 566         int rc;
 567
 568         BUILD_BUG_ON(NVRAM_BLOCK_LEN != 16);
 569
 570         if (ppc_md.nvram_size == NULL || ppc_md.nvram_size() <= 0)
 571                 return  -ENODEV;
 572
 573         rc = misc_register(&nvram_dev);
 574         if (rc != 0) {
 575                 printk(KERN_ERR "nvram_init: failed to register device\n");
 576                 return rc;
 577         }
 578
 579         /* initialize our anchor for the nvram partition list */
 580         nvram_part = kmalloc(sizeof(struct nvram_partition), GFP_KERNEL);
 581         if (!nvram_part) {
 582                 printk(KERN_ERR "nvram_init: Failed kmalloc\n");
 583                 return -ENOMEM;
 584         }
 585         INIT_LIST_HEAD(&nvram_part->partition);
 586
 587         /* Get all the NVRAM partitions */
 588         error = nvram_scan_partitions();
 589         if (error) {
 590                 printk(KERN_ERR "nvram_init: Failed nvram_scan_partitions\n");
 591                 return error;
 592         }
 593
 594         if(nvram_setup_partition())
 595                 printk(KERN_WARNING "nvram_init: Could not find nvram partition"
 596                        " for nvram buffered error logging.\n");
 597
 598 #ifdef DEBUG_NVRAM
 599         nvram_print_partitions("NVRAM Partitions");
 600 #endif
 601
 602         return rc;
 603 }
 604
 605 void __exit nvram_cleanup(void)
 606 {
 607         misc_deregister( &nvram_dev );
 608 }
 609
 610
 611 #ifdef CONFIG_PPC_PSERIES
 612
 613 /* nvram_write_error_log
 614  *
 615  * We need to buffer the error logs into nvram to ensure that we have
 616  * the failure information to decode.  If we have a severe error there
 617  * is no way to guarantee that the OS or the machine is in a state to
 618  * get back to user land and write the error to disk.  For example if
 619  * the SCSI device driver causes a Machine Check by writing to a bad
 620  * IO address, there is no way of guaranteeing that the device driver
 621  * is in any state that is would also be able to write the error data
 622  * captured to disk, thus we buffer it in NVRAM for analysis on the
 623  * next boot.
 624  *
 625  * In NVRAM the partition containing the error log buffer will looks like:
 626  * Header (in bytes):
 627  * +-----------+----------+--------+------------+------------------+
 628  * | signature | checksum | length | name       | data             |
 629  * |0          |1         |2      3|4         15|16        length-1|
 630  * +-----------+----------+--------+------------+------------------+
 631  *
 632  * The 'data' section would look like (in bytes):
 633  * +--------------+------------+-----------------------------------+
 634  * | event_logged | sequence # | error log                         |
 635  * |0            3|4          7|8            nvram_error_log_size-1|
 636  * +--------------+------------+-----------------------------------+
 637  *
 638  * event_logged: 0 if event has not been logged to syslog, 1 if it has
 639  * sequence #: The unique sequence # for each event. (until it wraps)
 640  * error log: The error log from event_scan
 641  */
 642 int nvram_write_error_log(char * buff, int length,
 643                           unsigned int err_type, unsigned int error_log_cnt)
 644 {
 645         int rc;
 646         loff_t tmp_index;
 647         struct err_log_info info;
 648
 649         if (nvram_error_log_index == -1) {
 650                 return -ESPIPE;
 651         }
 652
 653         if (length > nvram_error_log_size) {
 654                 length = nvram_error_log_size;
 655         }
 656
 657         info.error_type = err_type;
 658         info.seq_num = error_log_cnt;
 659
 660         tmp_index = nvram_error_log_index;
 661
 662         rc = ppc_md.nvram_write((char *)&info, sizeof(struct err_log_info), &tmp_index);
 663         if (rc <= 0) {
 664                 printk(KERN_ERR "nvram_write_error_log: Failed nvram_write (%d)\n", rc);
 665                 return rc;
 666         }
 667
 668         rc = ppc_md.nvram_write(buff, length, &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         return 0;
 675 }
 676
 677 /* nvram_read_error_log
 678  *
 679  * Reads nvram for error log for at most 'length'
 680  */
 681 int nvram_read_error_log(char * buff, int length,
 682                          unsigned int * err_type, unsigned int * error_log_cnt)
 683 {
 684         int rc;
 685         loff_t tmp_index;
 686         struct err_log_info info;
 687
 688         if (nvram_error_log_index == -1)
 689                 return -1;
 690
 691         if (length > nvram_error_log_size)
 692                 length = nvram_error_log_size;
 693
 694         tmp_index = nvram_error_log_index;
 695
 696         rc = ppc_md.nvram_read((char *)&info, sizeof(struct err_log_info), &tmp_index);
 697         if (rc <= 0) {
 698                 printk(KERN_ERR "nvram_read_error_log: Failed nvram_read (%d)\n", rc);
 699                 return rc;
 700         }
 701
 702         rc = ppc_md.nvram_read(buff, length, &tmp_index);
 703         if (rc <= 0) {
 704                 printk(KERN_ERR "nvram_read_error_log: Failed nvram_read (%d)\n", rc);
 705                 return rc;
 706         }
 707
 708         *error_log_cnt = info.seq_num;
 709         *err_type = info.error_type;
 710
 711         return 0;
 712 }
 713
 714 /* This doesn't actually zero anything, but it sets the event_logged
 715  * word to tell that this event is safely in syslog.
 716  */
 717 int nvram_clear_error_log(void)
 718 {
 719         loff_t tmp_index;
 720         int clear_word = ERR_FLAG_ALREADY_LOGGED;
 721         int rc;
 722
 723         if (nvram_error_log_index == -1)
 724                 return -1;
 725
 726         tmp_index = nvram_error_log_index;
 727
 728         rc = ppc_md.nvram_write((char *)&clear_word, sizeof(int), &tmp_index);
 729         if (rc <= 0) {
 730                 printk(KERN_ERR "nvram_clear_error_log: Failed nvram_write (%d)\n", rc);
 731                 return rc;
 732         }
 733
 734         return 0;
 735 }
 736
 737 #endif /* CONFIG_PPC_PSERIES */
 738
 739 module_init(nvram_init);
 740 module_exit(nvram_cleanup);
 741 MODULE_LICENSE("GPL");