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 list_head * p;
 342         struct nvram_partition * part;
 343         struct nvram_partition * new_part = NULL;
 344         struct nvram_partition * free_part = NULL;
 345         int seq_init[2] = { 0, 0 };
 346         loff_t tmp_index;
 347         long size = 0;
 348         int rc;
 349
 350         /* Find a free partition that will give us the maximum needed size
 351            If can't find one that will give us the minimum size needed */
 352         list_for_each(p, &nvram_part->partition) {
 353                 part = list_entry(p, struct nvram_partition, partition);
 354                 if (part->header.signature != NVRAM_SIG_FREE)
 355                         continue;
 356
 357                 if (part->header.length >= NVRAM_MAX_REQ) {
 358                         size = NVRAM_MAX_REQ;
 359                         free_part = part;
 360                         break;
 361                 }
 362                 if (!size && part->header.length >= NVRAM_MIN_REQ) {
 363                         size = NVRAM_MIN_REQ;
 364                         free_part = part;
 365                 }
 366         }
 367         if (!size) {
 368                 return -ENOSPC;
 369         }
 370
 371         /* Create our OS partition */
 372         new_part = (struct nvram_partition *)
 373                 kmalloc(sizeof(struct nvram_partition), GFP_KERNEL);
 374         if (!new_part) {
 375                 printk(KERN_ERR "nvram_create_os_partition: kmalloc failed\n");
 376                 return -ENOMEM;
 377         }
 378
 379         new_part->index = free_part->index;
 380         new_part->header.signature = NVRAM_SIG_OS;
 381         new_part->header.length = size;
 382         sprintf(new_part->header.name, "ppc64,linux");
 383         new_part->header.checksum = nvram_checksum(&new_part->header);
 384
 385         rc = nvram_write_header(new_part);
 386         if (rc <= 0) {
 387                 printk(KERN_ERR "nvram_create_os_partition: nvram_write_header \
 388                                 failed (%d)\n", rc);
 389                 return rc;
 390         }
 391
 392         /* make sure and initialize to zero the sequence number and the error
 393            type logged */
 394         tmp_index = new_part->index + NVRAM_HEADER_LEN;
 395         rc = ppc_md.nvram_write((char *)&seq_init, sizeof(seq_init), &tmp_index);
 396         if (rc <= 0) {
 397                 printk(KERN_ERR "nvram_create_os_partition: nvram_write failed (%d)\n", rc);
 398                 return rc;
 399         }
 400
 401         nvram_error_log_index = new_part->index + NVRAM_HEADER_LEN;
 402         nvram_error_log_size = ((part->header.length - 1) *
 403                                 NVRAM_BLOCK_LEN) - sizeof(struct err_log_info);
 404
 405         list_add_tail(&new_part->partition, &free_part->partition);
 406
 407         if (free_part->header.length <= size) {
 408                 list_del(&free_part->partition);
 409                 kfree(free_part);
 410                 return 0;
 411         }
 412
 413         /* Adjust the partition we stole the space from */
 414         free_part->index += size * NVRAM_BLOCK_LEN;
 415         free_part->header.length -= size;
 416         free_part->header.checksum = nvram_checksum(&free_part->header);
 417
 418         rc = nvram_write_header(free_part);
 419         if (rc <= 0) {
 420                 printk(KERN_ERR "nvram_create_os_partition: nvram_write_header "
 421                        "failed (%d)\n", rc);
 422                 return rc;
 423         }
 424
 425         return 0;
 426 }
 427
 428
 429 /* nvram_setup_partition
 430  *
 431  * This will setup the partition we need for buffering the
 432  * error logs and cleanup partitions if needed.
 433  *
 434  * The general strategy is the following:
 435  * 1.) If there is ppc64,linux partition large enough then use it.
 436  * 2.) If there is not a ppc64,linux partition large enough, search
 437  * for a free partition that is large enough.
 438  * 3.) If there is not a free partition large enough remove
 439  * _all_ OS partitions and consolidate the space.
 440  * 4.) Will first try getting a chunk that will satisfy the maximum
 441  * error log size (NVRAM_MAX_REQ).
 442  * 5.) If the max chunk cannot be allocated then try finding a chunk
 443  * that will satisfy the minum needed (NVRAM_MIN_REQ).
 444  */
 445 static int nvram_setup_partition(void)
 446 {
 447         struct list_head * p;
 448         struct nvram_partition * part;
 449         int rc;
 450
 451         /* For now, we don't do any of this on pmac, until I
 452          * have figured out if it's worth killing some unused stuffs
 453          * in our nvram, as Apple defined partitions use pretty much
 454          * all of the space
 455          */
 456         if (systemcfg->platform == PLATFORM_POWERMAC)
 457                 return -ENOSPC;
 458
 459         /* see if we have an OS partition that meets our needs.
 460            will try getting the max we need.  If not we'll delete
 461            partitions and try again. */
 462         list_for_each(p, &nvram_part->partition) {
 463                 part = list_entry(p, struct nvram_partition, partition);
 464                 if (part->header.signature != NVRAM_SIG_OS)
 465                         continue;
 466
 467                 if (strcmp(part->header.name, "ppc64,linux"))
 468                         continue;
 469
 470                 if (part->header.length >= NVRAM_MIN_REQ) {
 471                         /* found our partition */
 472                         nvram_error_log_index = part->index + NVRAM_HEADER_LEN;
 473                         nvram_error_log_size = ((part->header.length - 1) *
 474                                                 NVRAM_BLOCK_LEN) - sizeof(struct err_log_info);
 475                         return 0;
 476                 }
 477         }
 478
 479         /* try creating a partition with the free space we have */
 480         rc = nvram_create_os_partition();
 481         if (!rc) {
 482                 return 0;
 483         }
 484
 485         /* need to free up some space */
 486         rc = nvram_remove_os_partition();
 487         if (rc) {
 488                 return rc;
 489         }
 490
 491         /* create a partition in this new space */
 492         rc = nvram_create_os_partition();
 493         if (rc) {
 494                 printk(KERN_ERR "nvram_create_os_partition: Could not find a "
 495                        "NVRAM partition large enough\n");
 496                 return rc;
 497         }
 498
 499         return 0;
 500 }
 501
 502
 503 static int nvram_scan_partitions(void)
 504 {
 505         loff_t cur_index = 0;
 506         struct nvram_header phead;
 507         struct nvram_partition * tmp_part;
 508         unsigned char c_sum;
 509         char * header;
 510         int total_size;
 511         int err;
 512
 513         if (ppc_md.nvram_size == NULL)
 514                 return -ENODEV;
 515         total_size = ppc_md.nvram_size();
 516
 517         header = (char *) kmalloc(NVRAM_HEADER_LEN, GFP_KERNEL);
 518         if (!header) {
 519                 printk(KERN_ERR "nvram_scan_partitions: Failed kmalloc\n");
 520                 return -ENOMEM;
 521         }
 522
 523         while (cur_index < total_size) {
 524
 525                 err = ppc_md.nvram_read(header, NVRAM_HEADER_LEN, &cur_index);
 526                 if (err != NVRAM_HEADER_LEN) {
 527                         printk(KERN_ERR "nvram_scan_partitions: Error parsing "
 528                                "nvram partitions\n");
 529                         goto out;
 530                 }
 531
 532                 cur_index -= NVRAM_HEADER_LEN; /* nvram_read will advance us */
 533
 534                 memcpy(&phead, header, NVRAM_HEADER_LEN);
 535
 536                 err = 0;
 537                 c_sum = nvram_checksum(&phead);
 538                 if (c_sum != phead.checksum) {
 539                         printk(KERN_WARNING "WARNING: nvram partition checksum"
 540                                " was %02x, should be %02x!\n",
 541                                phead.checksum, c_sum);
 542                         printk(KERN_WARNING "Terminating nvram partition scan\n");
 543                         goto out;
 544                 }
 545                 if (!phead.length) {
 546                         printk(KERN_WARNING "WARNING: nvram corruption "
 547                                "detected: 0-length partition\n");
 548                         goto out;
 549                 }
 550                 tmp_part = (struct nvram_partition *)
 551                         kmalloc(sizeof(struct nvram_partition), GFP_KERNEL);
 552                 err = -ENOMEM;
 553                 if (!tmp_part) {
 554                         printk(KERN_ERR "nvram_scan_partitions: kmalloc failed\n");
 555                         goto out;
 556                 }
 557
 558                 memcpy(&tmp_part->header, &phead, NVRAM_HEADER_LEN);
 559                 tmp_part->index = cur_index;
 560                 list_add_tail(&tmp_part->partition, &nvram_part->partition);
 561
 562                 cur_index += phead.length * NVRAM_BLOCK_LEN;
 563         }
 564         err = 0;
 565
 566  out:
 567         kfree(header);
 568         return err;
 569 }
 570
 571 static int __init nvram_init(void)
 572 {
 573         int error;
 574         int rc;
 575
 576         if (ppc_md.nvram_size == NULL || ppc_md.nvram_size() <= 0)
 577                 return  -ENODEV;
 578
 579         rc = misc_register(&nvram_dev);
 580         if (rc != 0) {
 581                 printk(KERN_ERR "nvram_init: failed to register device\n");
 582                 return rc;
 583         }
 584
 585         /* initialize our anchor for the nvram partition list */
 586         nvram_part = (struct nvram_partition *) kmalloc(sizeof(struct nvram_partition), GFP_KERNEL);
 587         if (!nvram_part) {
 588                 printk(KERN_ERR "nvram_init: Failed kmalloc\n");
 589                 return -ENOMEM;
 590         }
 591         INIT_LIST_HEAD(&nvram_part->partition);
 592
 593         /* Get all the NVRAM partitions */
 594         error = nvram_scan_partitions();
 595         if (error) {
 596                 printk(KERN_ERR "nvram_init: Failed nvram_scan_partitions\n");
 597                 return error;
 598         }
 599
 600         if(nvram_setup_partition())
 601                 printk(KERN_WARNING "nvram_init: Could not find nvram partition"
 602                        " for nvram buffered error logging.\n");
 603
 604 #ifdef DEBUG_NVRAM
 605         nvram_print_partitions("NVRAM Partitions");
 606 #endif
 607
 608         return rc;
 609 }
 610
 611 void __exit nvram_cleanup(void)
 612 {
 613         misc_deregister( &nvram_dev );
 614 }
 615
 616
 617 #ifdef CONFIG_PPC_PSERIES
 618
 619 /* nvram_write_error_log
 620  *
 621  * We need to buffer the error logs into nvram to ensure that we have
 622  * the failure information to decode.  If we have a severe error there
 623  * is no way to guarantee that the OS or the machine is in a state to
 624  * get back to user land and write the error to disk.  For example if
 625  * the SCSI device driver causes a Machine Check by writing to a bad
 626  * IO address, there is no way of guaranteeing that the device driver
 627  * is in any state that is would also be able to write the error data
 628  * captured to disk, thus we buffer it in NVRAM for analysis on the
 629  * next boot.
 630  *
 631  * In NVRAM the partition containing the error log buffer will looks like:
 632  * Header (in bytes):
 633  * +-----------+----------+--------+------------+------------------+
 634  * | signature | checksum | length | name       | data             |
 635  * |0          |1         |2      3|4         15|16        length-1|
 636  * +-----------+----------+--------+------------+------------------+
 637  *
 638  * The 'data' section would look like (in bytes):
 639  * +--------------+------------+-----------------------------------+
 640  * | event_logged | sequence # | error log                         |
 641  * |0            3|4          7|8            nvram_error_log_size-1|
 642  * +--------------+------------+-----------------------------------+
 643  *
 644  * event_logged: 0 if event has not been logged to syslog, 1 if it has
 645  * sequence #: The unique sequence # for each event. (until it wraps)
 646  * error log: The error log from event_scan
 647  */
 648 int nvram_write_error_log(char * buff, int length, unsigned int err_type)
 649 {
 650         int rc;
 651         loff_t tmp_index;
 652         struct err_log_info info;
 653
 654         if (no_logging) {
 655                 return -EPERM;
 656         }
 657
 658         if (nvram_error_log_index == -1) {
 659                 return -ESPIPE;
 660         }
 661
 662         if (length > nvram_error_log_size) {
 663                 length = nvram_error_log_size;
 664         }
 665
 666         info.error_type = err_type;
 667         info.seq_num = error_log_cnt;
 668
 669         tmp_index = nvram_error_log_index;
 670
 671         rc = ppc_md.nvram_write((char *)&info, sizeof(struct err_log_info), &tmp_index);
 672         if (rc <= 0) {
 673                 printk(KERN_ERR "nvram_write_error_log: Failed nvram_write (%d)\n", rc);
 674                 return rc;
 675         }
 676
 677         rc = ppc_md.nvram_write(buff, length, &tmp_index);
 678         if (rc <= 0) {
 679                 printk(KERN_ERR "nvram_write_error_log: Failed nvram_write (%d)\n", rc);
 680                 return rc;
 681         }
 682
 683         return 0;
 684 }
 685
 686 /* nvram_read_error_log
 687  *
 688  * Reads nvram for error log for at most 'length'
 689  */
 690 int nvram_read_error_log(char * buff, int length, unsigned int * err_type)
 691 {
 692         int rc;
 693         loff_t tmp_index;
 694         struct err_log_info info;
 695
 696         if (nvram_error_log_index == -1)
 697                 return -1;
 698
 699         if (length > nvram_error_log_size)
 700                 length = nvram_error_log_size;
 701
 702         tmp_index = nvram_error_log_index;
 703
 704         rc = ppc_md.nvram_read((char *)&info, sizeof(struct err_log_info), &tmp_index);
 705         if (rc <= 0) {
 706                 printk(KERN_ERR "nvram_read_error_log: Failed nvram_read (%d)\n", rc);
 707                 return rc;
 708         }
 709
 710         rc = ppc_md.nvram_read(buff, length, &tmp_index);
 711         if (rc <= 0) {
 712                 printk(KERN_ERR "nvram_read_error_log: Failed nvram_read (%d)\n", rc);
 713                 return rc;
 714         }
 715
 716         error_log_cnt = info.seq_num;
 717         *err_type = info.error_type;
 718
 719         return 0;
 720 }
 721
 722 /* This doesn't actually zero anything, but it sets the event_logged
 723  * word to tell that this event is safely in syslog.
 724  */
 725 int nvram_clear_error_log(void)
 726 {
 727         loff_t tmp_index;
 728         int clear_word = ERR_FLAG_ALREADY_LOGGED;
 729         int rc;
 730
 731         tmp_index = nvram_error_log_index;
 732
 733         rc = ppc_md.nvram_write((char *)&clear_word, sizeof(int), &tmp_index);
 734         if (rc <= 0) {
 735                 printk(KERN_ERR "nvram_clear_error_log: Failed nvram_write (%d)\n", rc);
 736                 return rc;
 737         }
 738
 739         return 0;
 740 }
 741
 742 #endif /* CONFIG_PPC_PSERIES */
 743
 744 module_init(nvram_init);
 745 module_exit(nvram_cleanup);
 746 MODULE_LICENSE("GPL");