arch/ppc64/kernel/rtas.c

   1 /*
   2  *
   3  * Procedures for interfacing to the RTAS on CHRP machines.
   4  *
   5  * Peter Bergner, IBM   March 2001.
   6  * Copyright (C) 2001 IBM.
   7  *
   8  *      This program is free software; you can redistribute it and/or
   9  *      modify it under the terms of the GNU General Public License
  10  *      as published by the Free Software Foundation; either version
  11  *      2 of the License, or (at your option) any later version.
  12  */
  13
  14 #include <stdarg.h>
  15 #include <linux/kernel.h>
  16 #include <linux/types.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20
  21 #include <asm/prom.h>
  22 #include <asm/rtas.h>
  23 #include <asm/semaphore.h>
  24 #include <asm/machdep.h>
  25 #include <asm/page.h>
  26 #include <asm/param.h>
  27 #include <asm/system.h>
  28 #include <asm/abs_addr.h>
  29 #include <asm/udbg.h>
  30 #include <asm/delay.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/systemcfg.h>
  33
  34 struct flash_block_list_header rtas_firmware_flash_list = {0, NULL};
  35
  36 struct rtas_t rtas = {
  37         .lock = SPIN_LOCK_UNLOCKED
  38 };
  39
  40 EXPORT_SYMBOL(rtas);
  41
  42 char rtas_err_buf[RTAS_ERROR_LOG_MAX];
  43
  44 DEFINE_SPINLOCK(rtas_data_buf_lock);
  45 char rtas_data_buf[RTAS_DATA_BUF_SIZE]__page_aligned;
  46 unsigned long rtas_rmo_buf;
  47
  48 void
  49 call_rtas_display_status(unsigned char c)
  50 {
  51         struct rtas_args *args = &rtas.args;
  52         unsigned long s;
  53
  54         if (!rtas.base)
  55                 return;
  56         spin_lock_irqsave(&rtas.lock, s);
  57
  58         args->token = 10;
  59         args->nargs = 1;
  60         args->nret  = 1;
  61         args->rets  = (rtas_arg_t *)&(args->args[1]);
  62         args->args[0] = (int)c;
  63
  64         enter_rtas(__pa(args));
  65
  66         spin_unlock_irqrestore(&rtas.lock, s);
  67 }
  68
  69 void
  70 call_rtas_display_status_delay(unsigned char c)
  71 {
  72         static int pending_newline = 0;  /* did last write end with unprinted newline? */
  73         static int width = 16;
  74
  75         if (c == '\n') {
  76                 while (width-- > 0)
  77                         call_rtas_display_status(' ');
  78                 width = 16;
  79                 udelay(500000);
  80                 pending_newline = 1;
  81         } else {
  82                 if (pending_newline) {
  83                         call_rtas_display_status('\r');
  84                         call_rtas_display_status('\n');
  85                 }
  86                 pending_newline = 0;
  87                 if (width--) {
  88                         call_rtas_display_status(c);
  89                         udelay(10000);
  90                 }
  91         }
  92 }
  93
  94 int
  95 rtas_token(const char *service)
  96 {
  97         int *tokp;
  98         if (rtas.dev == NULL) {
  99                 PPCDBG(PPCDBG_RTAS,"\tNo rtas device in device-tree...\n");
 100                 return RTAS_UNKNOWN_SERVICE;
 101         }
 102         tokp = (int *) get_property(rtas.dev, service, NULL);
 103         return tokp ? *tokp : RTAS_UNKNOWN_SERVICE;
 104 }
 105
 106 /*
 107  * Return the firmware-specified size of the error log buffer
 108  *  for all rtas calls that require an error buffer argument.
 109  *  This includes 'check-exception' and 'rtas-last-error'.
 110  */
 111 int rtas_get_error_log_max(void)
 112 {
 113         static int rtas_error_log_max;
 114         if (rtas_error_log_max)
 115                 return rtas_error_log_max;
 116
 117         rtas_error_log_max = rtas_token ("rtas-error-log-max");
 118         if ((rtas_error_log_max == RTAS_UNKNOWN_SERVICE) ||
 119             (rtas_error_log_max > RTAS_ERROR_LOG_MAX)) {
 120                 printk (KERN_WARNING "RTAS: bad log buffer size %d\n", rtas_error_log_max);
 121                 rtas_error_log_max = RTAS_ERROR_LOG_MAX;
 122         }
 123         return rtas_error_log_max;
 124 }
 125
 126
 127 /** Return a copy of the detailed error text associated with the
 128  *  most recent failed call to rtas.  Because the error text
 129  *  might go stale if there are any other intervening rtas calls,
 130  *  this routine must be called atomically with whatever produced
 131  *  the error (i.e. with rtas.lock still held from the previous call).
 132  */
 133 static int
 134 __fetch_rtas_last_error(void)
 135 {
 136         struct rtas_args err_args, save_args;
 137         u32 bufsz;
 138
 139         bufsz = rtas_get_error_log_max();
 140
 141         err_args.token = rtas_token("rtas-last-error");
 142         err_args.nargs = 2;
 143         err_args.nret = 1;
 144
 145         err_args.args[0] = (rtas_arg_t)__pa(rtas_err_buf);
 146         err_args.args[1] = bufsz;
 147         err_args.args[2] = 0;
 148
 149         save_args = rtas.args;
 150         rtas.args = err_args;
 151
 152         enter_rtas(__pa(&rtas.args));
 153
 154         err_args = rtas.args;
 155         rtas.args = save_args;
 156
 157         return err_args.args[2];
 158 }
 159
 160 int rtas_call(int token, int nargs, int nret, int *outputs, ...)
 161 {
 162         va_list list;
 163         int i, logit = 0;
 164         unsigned long s;
 165         struct rtas_args *rtas_args;
 166         char * buff_copy = NULL;
 167         int ret;
 168
 169         PPCDBG(PPCDBG_RTAS, "Entering rtas_call\n");
 170         PPCDBG(PPCDBG_RTAS, "\ttoken    = 0x%x\n", token);
 171         PPCDBG(PPCDBG_RTAS, "\tnargs    = %d\n", nargs);
 172         PPCDBG(PPCDBG_RTAS, "\tnret     = %d\n", nret);
 173         PPCDBG(PPCDBG_RTAS, "\t&outputs = 0x%lx\n", outputs);
 174         if (token == RTAS_UNKNOWN_SERVICE)
 175                 return -1;
 176
 177         /* Gotta do something different here, use global lock for now... */
 178         spin_lock_irqsave(&rtas.lock, s);
 179         rtas_args = &rtas.args;
 180
 181         rtas_args->token = token;
 182         rtas_args->nargs = nargs;
 183         rtas_args->nret  = nret;
 184         rtas_args->rets  = (rtas_arg_t *)&(rtas_args->args[nargs]);
 185         va_start(list, outputs);
 186         for (i = 0; i < nargs; ++i) {
 187                 rtas_args->args[i] = va_arg(list, rtas_arg_t);
 188                 PPCDBG(PPCDBG_RTAS, "\tnarg[%d] = 0x%x\n", i, rtas_args->args[i]);
 189         }
 190         va_end(list);
 191
 192         for (i = 0; i < nret; ++i)
 193                 rtas_args->rets[i] = 0;
 194
 195         PPCDBG(PPCDBG_RTAS, "\tentering rtas with 0x%lx\n",
 196                 __pa(rtas_args));
 197         enter_rtas(__pa(rtas_args));
 198         PPCDBG(PPCDBG_RTAS, "\treturned from rtas ...\n");
 199
 200         /* A -1 return code indicates that the last command couldn't
 201            be completed due to a hardware error. */
 202         if (rtas_args->rets[0] == -1)
 203                 logit = (__fetch_rtas_last_error() == 0);
 204
 205         ifppcdebug(PPCDBG_RTAS) {
 206                 for(i=0; i < nret ;i++)
 207                         udbg_printf("\tnret[%d] = 0x%lx\n", i, (ulong)rtas_args->rets[i]);
 208         }
 209
 210         if (nret > 1 && outputs != NULL)
 211                 for (i = 0; i < nret-1; ++i)
 212                         outputs[i] = rtas_args->rets[i+1];
 213         ret = (nret > 0)? rtas_args->rets[0]: 0;
 214
 215         /* Log the error in the unlikely case that there was one. */
 216         if (unlikely(logit)) {
 217                 buff_copy = rtas_err_buf;
 218                 if (mem_init_done) {
 219                         buff_copy = kmalloc(RTAS_ERROR_LOG_MAX, GFP_ATOMIC);
 220                         if (buff_copy)
 221                                 memcpy(buff_copy, rtas_err_buf,
 222                                        RTAS_ERROR_LOG_MAX);
 223                 }
 224         }
 225
 226         /* Gotta do something different here, use global lock for now... */
 227         spin_unlock_irqrestore(&rtas.lock, s);
 228
 229         if (buff_copy) {
 230                 log_error(buff_copy, ERR_TYPE_RTAS_LOG, 0);
 231                 if (mem_init_done)
 232                         kfree(buff_copy);
 233         }
 234         return ret;
 235 }
 236
 237 /* Given an RTAS status code of 990n compute the hinted delay of 10^n
 238  * (last digit) milliseconds.  For now we bound at n=5 (100 sec).
 239  */
 240 unsigned int
 241 rtas_extended_busy_delay_time(int status)
 242 {
 243         int order = status - 9900;
 244         unsigned long ms;
 245
 246         if (order < 0)
 247                 order = 0;      /* RTC depends on this for -2 clock busy */
 248         else if (order > 5)
 249                 order = 5;      /* bound */
 250
 251         /* Use microseconds for reasonable accuracy */
 252         for (ms=1; order > 0; order--)
 253                 ms *= 10;
 254
 255         return ms;
 256 }
 257
 258 int rtas_error_rc(int rtas_rc)
 259 {
 260         int rc;
 261
 262         switch (rtas_rc) {
 263                 case -1:                /* Hardware Error */
 264                         rc = -EIO;
 265                         break;
 266                 case -3:                /* Bad indicator/domain/etc */
 267                         rc = -EINVAL;
 268                         break;
 269                 case -9000:             /* Isolation error */
 270                         rc = -EFAULT;
 271                         break;
 272                 case -9001:             /* Outstanding TCE/PTE */
 273                         rc = -EEXIST;
 274                         break;
 275                 case -9002:             /* No usable slot */
 276                         rc = -ENODEV;
 277                         break;
 278                 default:
 279                         printk(KERN_ERR "%s: unexpected RTAS error %d\n",
 280                                         __FUNCTION__, rtas_rc);
 281                         rc = -ERANGE;
 282                         break;
 283         }
 284         return rc;
 285 }
 286
 287 int rtas_get_power_level(int powerdomain, int *level)
 288 {
 289         int token = rtas_token("get-power-level");
 290         int rc;
 291
 292         if (token == RTAS_UNKNOWN_SERVICE)
 293                 return -ENOENT;
 294
 295         while ((rc = rtas_call(token, 1, 2, level, powerdomain)) == RTAS_BUSY)
 296                 udelay(1);
 297
 298         if (rc < 0)
 299                 return rtas_error_rc(rc);
 300         return rc;
 301 }
 302
 303 int rtas_set_power_level(int powerdomain, int level, int *setlevel)
 304 {
 305         int token = rtas_token("set-power-level");
 306         unsigned int wait_time;
 307         int rc;
 308
 309         if (token == RTAS_UNKNOWN_SERVICE)
 310                 return -ENOENT;
 311
 312         while (1) {
 313                 rc = rtas_call(token, 2, 2, setlevel, powerdomain, level);
 314                 if (rc == RTAS_BUSY)
 315                         udelay(1);
 316                 else if (rtas_is_extended_busy(rc)) {
 317                         wait_time = rtas_extended_busy_delay_time(rc);
 318                         udelay(wait_time * 1000);
 319                 } else
 320                         break;
 321         }
 322
 323         if (rc < 0)
 324                 return rtas_error_rc(rc);
 325         return rc;
 326 }
 327
 328 int rtas_get_sensor(int sensor, int index, int *state)
 329 {
 330         int token = rtas_token("get-sensor-state");
 331         unsigned int wait_time;
 332         int rc;
 333
 334         if (token == RTAS_UNKNOWN_SERVICE)
 335                 return -ENOENT;
 336
 337         while (1) {
 338                 rc = rtas_call(token, 2, 2, state, sensor, index);
 339                 if (rc == RTAS_BUSY)
 340                         udelay(1);
 341                 else if (rtas_is_extended_busy(rc)) {
 342                         wait_time = rtas_extended_busy_delay_time(rc);
 343                         udelay(wait_time * 1000);
 344                 } else
 345                         break;
 346         }
 347
 348         if (rc < 0)
 349                 return rtas_error_rc(rc);
 350         return rc;
 351 }
 352
 353 int rtas_set_indicator(int indicator, int index, int new_value)
 354 {
 355         int token = rtas_token("set-indicator");
 356         unsigned int wait_time;
 357         int rc;
 358
 359         if (token == RTAS_UNKNOWN_SERVICE)
 360                 return -ENOENT;
 361
 362         while (1) {
 363                 rc = rtas_call(token, 3, 1, NULL, indicator, index, new_value);
 364                 if (rc == RTAS_BUSY)
 365                         udelay(1);
 366                 else if (rtas_is_extended_busy(rc)) {
 367                         wait_time = rtas_extended_busy_delay_time(rc);
 368                         udelay(wait_time * 1000);
 369                 }
 370                 else
 371                         break;
 372         }
 373
 374         if (rc < 0)
 375                 return rtas_error_rc(rc);
 376         return rc;
 377 }
 378
 379 #define FLASH_BLOCK_LIST_VERSION (1UL)
 380 static void
 381 rtas_flash_firmware(void)
 382 {
 383         unsigned long image_size;
 384         struct flash_block_list *f, *next, *flist;
 385         unsigned long rtas_block_list;
 386         int i, status, update_token;
 387
 388         update_token = rtas_token("ibm,update-flash-64-and-reboot");
 389         if (update_token == RTAS_UNKNOWN_SERVICE) {
 390                 printk(KERN_ALERT "FLASH: ibm,update-flash-64-and-reboot is not available -- not a service partition?\n");
 391                 printk(KERN_ALERT "FLASH: firmware will not be flashed\n");
 392                 return;
 393         }
 394
 395         /* NOTE: the "first" block list is a global var with no data
 396          * blocks in the kernel data segment.  We do this because
 397          * we want to ensure this block_list addr is under 4GB.
 398          */
 399         rtas_firmware_flash_list.num_blocks = 0;
 400         flist = (struct flash_block_list *)&rtas_firmware_flash_list;
 401         rtas_block_list = virt_to_abs(flist);
 402         if (rtas_block_list >= 4UL*1024*1024*1024) {
 403                 printk(KERN_ALERT "FLASH: kernel bug...flash list header addr above 4GB\n");
 404                 return;
 405         }
 406
 407         printk(KERN_ALERT "FLASH: preparing saved firmware image for flash\n");
 408         /* Update the block_list in place. */
 409         image_size = 0;
 410         for (f = flist; f; f = next) {
 411                 /* Translate data addrs to absolute */
 412                 for (i = 0; i < f->num_blocks; i++) {
 413                         f->blocks[i].data = (char *)virt_to_abs(f->blocks[i].data);
 414                         image_size += f->blocks[i].length;
 415                 }
 416                 next = f->next;
 417                 /* Don't translate NULL pointer for last entry */
 418                 if (f->next)
 419                         f->next = (struct flash_block_list *)virt_to_abs(f->next);
 420                 else
 421                         f->next = NULL;
 422                 /* make num_blocks into the version/length field */
 423                 f->num_blocks = (FLASH_BLOCK_LIST_VERSION << 56) | ((f->num_blocks+1)*16);
 424         }
 425
 426         printk(KERN_ALERT "FLASH: flash image is %ld bytes\n", image_size);
 427         printk(KERN_ALERT "FLASH: performing flash and reboot\n");
 428         ppc_md.progress("Flashing        \n", 0x0);
 429         ppc_md.progress("Please Wait...  ", 0x0);
 430         printk(KERN_ALERT "FLASH: this will take several minutes.  Do not power off!\n");
 431         status = rtas_call(update_token, 1, 1, NULL, rtas_block_list);
 432         switch (status) {       /* should only get "bad" status */
 433             case 0:
 434                 printk(KERN_ALERT "FLASH: success\n");
 435                 break;
 436             case -1:
 437                 printk(KERN_ALERT "FLASH: hardware error.  Firmware may not be not flashed\n");
 438                 break;
 439             case -3:
 440                 printk(KERN_ALERT "FLASH: image is corrupt or not correct for this platform.  Firmware not flashed\n");
 441                 break;
 442             case -4:
 443                 printk(KERN_ALERT "FLASH: flash failed when partially complete.  System may not reboot\n");
 444                 break;
 445             default:
 446                 printk(KERN_ALERT "FLASH: unknown flash return code %d\n", status);
 447                 break;
 448         }
 449 }
 450
 451 void rtas_flash_bypass_warning(void)
 452 {
 453         printk(KERN_ALERT "FLASH: firmware flash requires a reboot\n");
 454         printk(KERN_ALERT "FLASH: the firmware image will NOT be flashed\n");
 455 }
 456
 457
 458 void
 459 rtas_restart(char *cmd)
 460 {
 461         if (rtas_firmware_flash_list.next)
 462                 rtas_flash_firmware();
 463
 464         printk("RTAS system-reboot returned %d\n",
 465                rtas_call(rtas_token("system-reboot"), 0, 1, NULL));
 466         for (;;);
 467 }
 468
 469 void
 470 rtas_power_off(void)
 471 {
 472         if (rtas_firmware_flash_list.next)
 473                 rtas_flash_bypass_warning();
 474         /* allow power on only with power button press */
 475         printk("RTAS power-off returned %d\n",
 476                rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1));
 477         for (;;);
 478 }
 479
 480 void
 481 rtas_halt(void)
 482 {
 483         if (rtas_firmware_flash_list.next)
 484                 rtas_flash_bypass_warning();
 485         rtas_power_off();
 486 }
 487
 488 /* Must be in the RMO region, so we place it here */
 489 static char rtas_os_term_buf[2048];
 490
 491 void rtas_os_term(char *str)
 492 {
 493         int status;
 494
 495         if (RTAS_UNKNOWN_SERVICE == rtas_token("ibm,os-term"))
 496                 return;
 497
 498         snprintf(rtas_os_term_buf, 2048, "OS panic: %s", str);
 499
 500         do {
 501                 status = rtas_call(rtas_token("ibm,os-term"), 1, 1, NULL,
 502                                    __pa(rtas_os_term_buf));
 503
 504                 if (status == RTAS_BUSY)
 505                         udelay(1);
 506                 else if (status != 0)
 507                         printk(KERN_EMERG "ibm,os-term call failed %d\n",
 508                                status);
 509         } while (status == RTAS_BUSY);
 510 }
 511
 512
 513 asmlinkage int ppc_rtas(struct rtas_args __user *uargs)
 514 {
 515         struct rtas_args args;
 516         unsigned long flags;
 517         char * buff_copy;
 518         int nargs;
 519         int err_rc = 0;
 520
 521         if (!capable(CAP_SYS_ADMIN))
 522                 return -EPERM;
 523
 524         if (copy_from_user(&args, uargs, 3 * sizeof(u32)) != 0)
 525                 return -EFAULT;
 526
 527         nargs = args.nargs;
 528         if (nargs > ARRAY_SIZE(args.args)
 529             || args.nret > ARRAY_SIZE(args.args)
 530             || nargs + args.nret > ARRAY_SIZE(args.args))
 531                 return -EINVAL;
 532
 533         /* Copy in args. */
 534         if (copy_from_user(args.args, uargs->args,
 535                            nargs * sizeof(rtas_arg_t)) != 0)
 536                 return -EFAULT;
 537
 538         buff_copy = kmalloc(RTAS_ERROR_LOG_MAX, GFP_KERNEL);
 539
 540         spin_lock_irqsave(&rtas.lock, flags);
 541
 542         rtas.args = args;
 543         enter_rtas(__pa(&rtas.args));
 544         args = rtas.args;
 545
 546         args.rets = &args.args[nargs];
 547
 548         /* A -1 return code indicates that the last command couldn't
 549            be completed due to a hardware error. */
 550         if (args.rets[0] == -1) {
 551                 err_rc = __fetch_rtas_last_error();
 552                 if ((err_rc == 0) && buff_copy) {
 553                         memcpy(buff_copy, rtas_err_buf, RTAS_ERROR_LOG_MAX);
 554                 }
 555         }
 556
 557         spin_unlock_irqrestore(&rtas.lock, flags);
 558
 559         if (buff_copy) {
 560                 if ((args.rets[0] == -1) && (err_rc == 0)) {
 561                         log_error(buff_copy, ERR_TYPE_RTAS_LOG, 0);
 562                 }
 563                 kfree(buff_copy);
 564         }
 565
 566         /* Copy out args. */
 567         if (copy_to_user(uargs->args + nargs,
 568                          args.args + nargs,
 569                          args.nret * sizeof(rtas_arg_t)) != 0)
 570                 return -EFAULT;
 571
 572         return 0;
 573 }
 574
 575 /* This version can't take the spinlock, because it never returns */
 576
 577 struct rtas_args rtas_stop_self_args = {
 578         /* The token is initialized for real in setup_system() */
 579         .token = RTAS_UNKNOWN_SERVICE,
 580         .nargs = 0,
 581         .nret = 1,
 582         .rets = &rtas_stop_self_args.args[0],
 583 };
 584
 585 void rtas_stop_self(void)
 586 {
 587         struct rtas_args *rtas_args = &rtas_stop_self_args;
 588
 589         local_irq_disable();
 590
 591         BUG_ON(rtas_args->token == RTAS_UNKNOWN_SERVICE);
 592
 593         printk("cpu %u (hwid %u) Ready to die...\n",
 594                smp_processor_id(), hard_smp_processor_id());
 595         enter_rtas(__pa(rtas_args));
 596
 597         panic("Alas, I survived.\n");
 598 }
 599
 600 /*
 601  * Call early during boot, before mem init or bootmem, to retreive the RTAS
 602  * informations from the device-tree and allocate the RMO buffer for userland
 603  * accesses.
 604  */
 605 void __init rtas_initialize(void)
 606 {
 607         /* Get RTAS dev node and fill up our "rtas" structure with infos
 608          * about it.
 609          */
 610         rtas.dev = of_find_node_by_name(NULL, "rtas");
 611         if (rtas.dev) {
 612                 u32 *basep, *entryp;
 613                 u32 *sizep;
 614
 615                 basep = (u32 *)get_property(rtas.dev, "linux,rtas-base", NULL);
 616                 sizep = (u32 *)get_property(rtas.dev, "rtas-size", NULL);
 617                 if (basep != NULL && sizep != NULL) {
 618                         rtas.base = *basep;
 619                         rtas.size = *sizep;
 620                         entryp = (u32 *)get_property(rtas.dev, "linux,rtas-entry", NULL);
 621                         if (entryp == NULL) /* Ugh */
 622                                 rtas.entry = rtas.base;
 623                         else
 624                                 rtas.entry = *entryp;
 625                 } else
 626                         rtas.dev = NULL;
 627         }
 628         /* If RTAS was found, allocate the RMO buffer for it and look for
 629          * the stop-self token if any
 630          */
 631         if (rtas.dev) {
 632                 unsigned long rtas_region = RTAS_INSTANTIATE_MAX;
 633                 if (systemcfg->platform == PLATFORM_PSERIES_LPAR)
 634                         rtas_region = min(lmb.rmo_size, RTAS_INSTANTIATE_MAX);
 635
 636                 rtas_rmo_buf = lmb_alloc_base(RTAS_RMOBUF_MAX, PAGE_SIZE,
 637                                                         rtas_region);
 638
 639 #ifdef CONFIG_HOTPLUG_CPU
 640                 rtas_stop_self_args.token = rtas_token("stop-self");
 641 #endif /* CONFIG_HOTPLUG_CPU */
 642         }
 643
 644 }
 645
 646
 647 EXPORT_SYMBOL(rtas_firmware_flash_list);
 648 EXPORT_SYMBOL(rtas_token);
 649 EXPORT_SYMBOL(rtas_call);
 650 EXPORT_SYMBOL(rtas_data_buf);
 651 EXPORT_SYMBOL(rtas_data_buf_lock);
 652 EXPORT_SYMBOL(rtas_extended_busy_delay_time);
 653 EXPORT_SYMBOL(rtas_get_sensor);
 654 EXPORT_SYMBOL(rtas_get_power_level);
 655 EXPORT_SYMBOL(rtas_set_power_level);
 656 EXPORT_SYMBOL(rtas_set_indicator);
 657 EXPORT_SYMBOL(rtas_get_error_log_max);