drivers/watchdog/octeon-wdt-main.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Octeon Watchdog driver
   4  *
   5  * Copyright (C) 2007-2017 Cavium, Inc.
   6  *
   7  * Converted to use WATCHDOG_CORE by Aaro Koskinen <aaro.koskinen@iki.fi>.
   8  *
   9  * Some parts derived from wdt.c
  10  *
  11  *      (c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  12  *                                              All Rights Reserved.
  13  *
  14  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  15  *      warranty for any of this software. This material is provided
  16  *      "AS-IS" and at no charge.
  17  *
  18  *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  19  *
  20  * The OCTEON watchdog has a maximum timeout of 2^32 * io_clock.
  21  * For most systems this is less than 10 seconds, so to allow for
  22  * software to request longer watchdog heartbeats, we maintain software
  23  * counters to count multiples of the base rate.  If the system locks
  24  * up in such a manner that we can not run the software counters, the
  25  * only result is a watchdog reset sooner than was requested.  But
  26  * that is OK, because in this case userspace would likely not be able
  27  * to do anything anyhow.
  28  *
  29  * The hardware watchdog interval we call the period.  The OCTEON
  30  * watchdog goes through several stages, after the first period an
  31  * irq is asserted, then if it is not reset, after the next period NMI
  32  * is asserted, then after an additional period a chip wide soft reset.
  33  * So for the software counters, we reset watchdog after each period
  34  * and decrement the counter.  But for the last two periods we need to
  35  * let the watchdog progress to the NMI stage so we disable the irq
  36  * and let it proceed.  Once in the NMI, we print the register state
  37  * to the serial port and then wait for the reset.
  38  *
  39  * A watchdog is maintained for each CPU in the system, that way if
  40  * one CPU suffers a lockup, we also get a register dump and reset.
  41  * The userspace ping resets the watchdog on all CPUs.
  42  *
  43  * Before userspace opens the watchdog device, we still run the
  44  * watchdogs to catch any lockups that may be kernel related.
  45  *
  46  */
  47
  48 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  49
  50 #include <linux/interrupt.h>
  51 #include <linux/watchdog.h>
  52 #include <linux/cpumask.h>
  53 #include <linux/module.h>
  54 #include <linux/delay.h>
  55 #include <linux/cpu.h>
  56 #include <linux/irq.h>
  57
  58 #include <asm/mipsregs.h>
  59 #include <asm/uasm.h>
  60
  61 #include <asm/octeon/octeon.h>
  62 #include <asm/octeon/cvmx-boot-vector.h>
  63 #include <asm/octeon/cvmx-ciu2-defs.h>
  64 #include <asm/octeon/cvmx-rst-defs.h>
  65
  66 /* Watchdog interrupt major block number (8 MSBs of intsn) */
  67 #define WD_BLOCK_NUMBER         0x01
  68
  69 static int divisor;
  70
  71 /* The count needed to achieve timeout_sec. */
  72 static unsigned int timeout_cnt;
  73
  74 /* The maximum period supported. */
  75 static unsigned int max_timeout_sec;
  76
  77 /* The current period.  */
  78 static unsigned int timeout_sec;
  79
  80 /* Set to non-zero when userspace countdown mode active */
  81 static bool do_countdown;
  82 static unsigned int countdown_reset;
  83 static unsigned int per_cpu_countdown[NR_CPUS];
  84
  85 static cpumask_t irq_enabled_cpus;
  86
  87 #define WD_TIMO 60                      /* Default heartbeat = 60 seconds */
  88
  89 #define CVMX_GSERX_SCRATCH(offset) (CVMX_ADD_IO_SEG(0x0001180090000020ull) + ((offset) & 15) * 0x1000000ull)
  90
  91 static int heartbeat = WD_TIMO;
  92 module_param(heartbeat, int, 0444);
  93 MODULE_PARM_DESC(heartbeat,
  94         "Watchdog heartbeat in seconds. (0 < heartbeat, default="
  95                                 __MODULE_STRING(WD_TIMO) ")");
  96
  97 static bool nowayout = WATCHDOG_NOWAYOUT;
  98 module_param(nowayout, bool, 0444);
  99 MODULE_PARM_DESC(nowayout,
 100         "Watchdog cannot be stopped once started (default="
 101                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 102
 103 static int disable;
 104 module_param(disable, int, 0444);
 105 MODULE_PARM_DESC(disable,
 106         "Disable the watchdog entirely (default=0)");
 107
 108 static struct cvmx_boot_vector_element *octeon_wdt_bootvector;
 109
 110 void octeon_wdt_nmi_stage2(void);
 111
 112 static int cpu2core(int cpu)
 113 {
 114 #ifdef CONFIG_SMP
 115         return cpu_logical_map(cpu) & 0x3f;
 116 #else
 117         return cvmx_get_core_num();
 118 #endif
 119 }
 120
 121 /**
 122  * Poke the watchdog when an interrupt is received
 123  *
 124  * @cpl:
 125  * @dev_id:
 126  *
 127  * Returns
 128  */
 129 static irqreturn_t octeon_wdt_poke_irq(int cpl, void *dev_id)
 130 {
 131         int cpu = raw_smp_processor_id();
 132         unsigned int core = cpu2core(cpu);
 133         int node = cpu_to_node(cpu);
 134
 135         if (do_countdown) {
 136                 if (per_cpu_countdown[cpu] > 0) {
 137                         /* We're alive, poke the watchdog */
 138                         cvmx_write_csr_node(node, CVMX_CIU_PP_POKEX(core), 1);
 139                         per_cpu_countdown[cpu]--;
 140                 } else {
 141                         /* Bad news, you are about to reboot. */
 142                         disable_irq_nosync(cpl);
 143                         cpumask_clear_cpu(cpu, &irq_enabled_cpus);
 144                 }
 145         } else {
 146                 /* Not open, just ping away... */
 147                 cvmx_write_csr_node(node, CVMX_CIU_PP_POKEX(core), 1);
 148         }
 149         return IRQ_HANDLED;
 150 }
 151
 152 /* From setup.c */
 153 extern int prom_putchar(char c);
 154
 155 /**
 156  * Write a string to the uart
 157  *
 158  * @str:        String to write
 159  */
 160 static void octeon_wdt_write_string(const char *str)
 161 {
 162         /* Just loop writing one byte at a time */
 163         while (*str)
 164                 prom_putchar(*str++);
 165 }
 166
 167 /**
 168  * Write a hex number out of the uart
 169  *
 170  * @value:      Number to display
 171  * @digits:     Number of digits to print (1 to 16)
 172  */
 173 static void octeon_wdt_write_hex(u64 value, int digits)
 174 {
 175         int d;
 176         int v;
 177
 178         for (d = 0; d < digits; d++) {
 179                 v = (value >> ((digits - d - 1) * 4)) & 0xf;
 180                 if (v >= 10)
 181                         prom_putchar('a' + v - 10);
 182                 else
 183                         prom_putchar('0' + v);
 184         }
 185 }
 186
 187 static const char reg_name[][3] = {
 188         "$0", "at", "v0", "v1", "a0", "a1", "a2", "a3",
 189         "a4", "a5", "a6", "a7", "t0", "t1", "t2", "t3",
 190         "s0", "s1", "s2", "s3", "s4", "s5", "s6", "s7",
 191         "t8", "t9", "k0", "k1", "gp", "sp", "s8", "ra"
 192 };
 193
 194 /**
 195  * NMI stage 3 handler. NMIs are handled in the following manner:
 196  * 1) The first NMI handler enables CVMSEG and transfers from
 197  * the bootbus region into normal memory. It is careful to not
 198  * destroy any registers.
 199  * 2) The second stage handler uses CVMSEG to save the registers
 200  * and create a stack for C code. It then calls the third level
 201  * handler with one argument, a pointer to the register values.
 202  * 3) The third, and final, level handler is the following C
 203  * function that prints out some useful infomration.
 204  *
 205  * @reg:    Pointer to register state before the NMI
 206  */
 207 void octeon_wdt_nmi_stage3(u64 reg[32])
 208 {
 209         u64 i;
 210
 211         unsigned int coreid = cvmx_get_core_num();
 212         /*
 213          * Save status and cause early to get them before any changes
 214          * might happen.
 215          */
 216         u64 cp0_cause = read_c0_cause();
 217         u64 cp0_status = read_c0_status();
 218         u64 cp0_error_epc = read_c0_errorepc();
 219         u64 cp0_epc = read_c0_epc();
 220
 221         /* Delay so output from all cores output is not jumbled together. */
 222         udelay(85000 * coreid);
 223
 224         octeon_wdt_write_string("\r\n*** NMI Watchdog interrupt on Core 0x");
 225         octeon_wdt_write_hex(coreid, 2);
 226         octeon_wdt_write_string(" ***\r\n");
 227         for (i = 0; i < 32; i++) {
 228                 octeon_wdt_write_string("\t");
 229                 octeon_wdt_write_string(reg_name[i]);
 230                 octeon_wdt_write_string("\t0x");
 231                 octeon_wdt_write_hex(reg[i], 16);
 232                 if (i & 1)
 233                         octeon_wdt_write_string("\r\n");
 234         }
 235         octeon_wdt_write_string("\terr_epc\t0x");
 236         octeon_wdt_write_hex(cp0_error_epc, 16);
 237
 238         octeon_wdt_write_string("\tepc\t0x");
 239         octeon_wdt_write_hex(cp0_epc, 16);
 240         octeon_wdt_write_string("\r\n");
 241
 242         octeon_wdt_write_string("\tstatus\t0x");
 243         octeon_wdt_write_hex(cp0_status, 16);
 244         octeon_wdt_write_string("\tcause\t0x");
 245         octeon_wdt_write_hex(cp0_cause, 16);
 246         octeon_wdt_write_string("\r\n");
 247
 248         /* The CIU register is different for each Octeon model. */
 249         if (OCTEON_IS_MODEL(OCTEON_CN68XX)) {
 250                 octeon_wdt_write_string("\tsrc_wd\t0x");
 251                 octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU2_SRC_PPX_IP2_WDOG(coreid)), 16);
 252                 octeon_wdt_write_string("\ten_wd\t0x");
 253                 octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU2_EN_PPX_IP2_WDOG(coreid)), 16);
 254                 octeon_wdt_write_string("\r\n");
 255                 octeon_wdt_write_string("\tsrc_rml\t0x");
 256                 octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU2_SRC_PPX_IP2_RML(coreid)), 16);
 257                 octeon_wdt_write_string("\ten_rml\t0x");
 258                 octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU2_EN_PPX_IP2_RML(coreid)), 16);
 259                 octeon_wdt_write_string("\r\n");
 260                 octeon_wdt_write_string("\tsum\t0x");
 261                 octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU2_SUM_PPX_IP2(coreid)), 16);
 262                 octeon_wdt_write_string("\r\n");
 263         } else if (!octeon_has_feature(OCTEON_FEATURE_CIU3)) {
 264                 octeon_wdt_write_string("\tsum0\t0x");
 265                 octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU_INTX_SUM0(coreid * 2)), 16);
 266                 octeon_wdt_write_string("\ten0\t0x");
 267                 octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU_INTX_EN0(coreid * 2)), 16);
 268                 octeon_wdt_write_string("\r\n");
 269         }
 270
 271         octeon_wdt_write_string("*** Chip soft reset soon ***\r\n");
 272
 273         /*
 274          * G-30204: We must trigger a soft reset before watchdog
 275          * does an incomplete job of doing it.
 276          */
 277         if (OCTEON_IS_OCTEON3() && !OCTEON_IS_MODEL(OCTEON_CN70XX)) {
 278                 u64 scr;
 279                 unsigned int node = cvmx_get_node_num();
 280                 unsigned int lcore = cvmx_get_local_core_num();
 281                 union cvmx_ciu_wdogx ciu_wdog;
 282
 283                 /*
 284                  * Wait for other cores to print out information, but
 285                  * not too long.  Do the soft reset before watchdog
 286                  * can trigger it.
 287                  */
 288                 do {
 289                         ciu_wdog.u64 = cvmx_read_csr_node(node, CVMX_CIU_WDOGX(lcore));
 290                 } while (ciu_wdog.s.cnt > 0x10000);
 291
 292                 scr = cvmx_read_csr_node(0, CVMX_GSERX_SCRATCH(0));
 293                 scr |= 1 << 11; /* Indicate watchdog in bit 11 */
 294                 cvmx_write_csr_node(0, CVMX_GSERX_SCRATCH(0), scr);
 295                 cvmx_write_csr_node(0, CVMX_RST_SOFT_RST, 1);
 296         }
 297 }
 298
 299 static int octeon_wdt_cpu_to_irq(int cpu)
 300 {
 301         unsigned int coreid;
 302         int node;
 303         int irq;
 304
 305         coreid = cpu2core(cpu);
 306         node = cpu_to_node(cpu);
 307
 308         if (octeon_has_feature(OCTEON_FEATURE_CIU3)) {
 309                 struct irq_domain *domain;
 310                 int hwirq;
 311
 312                 domain = octeon_irq_get_block_domain(node,
 313                                                      WD_BLOCK_NUMBER);
 314                 hwirq = WD_BLOCK_NUMBER << 12 | 0x200 | coreid;
 315                 irq = irq_find_mapping(domain, hwirq);
 316         } else {
 317                 irq = OCTEON_IRQ_WDOG0 + coreid;
 318         }
 319         return irq;
 320 }
 321
 322 static int octeon_wdt_cpu_pre_down(unsigned int cpu)
 323 {
 324         unsigned int core;
 325         int node;
 326         union cvmx_ciu_wdogx ciu_wdog;
 327
 328         core = cpu2core(cpu);
 329
 330         node = cpu_to_node(cpu);
 331
 332         /* Poke the watchdog to clear out its state */
 333         cvmx_write_csr_node(node, CVMX_CIU_PP_POKEX(core), 1);
 334
 335         /* Disable the hardware. */
 336         ciu_wdog.u64 = 0;
 337         cvmx_write_csr_node(node, CVMX_CIU_WDOGX(core), ciu_wdog.u64);
 338
 339         free_irq(octeon_wdt_cpu_to_irq(cpu), octeon_wdt_poke_irq);
 340         return 0;
 341 }
 342
 343 static int octeon_wdt_cpu_online(unsigned int cpu)
 344 {
 345         unsigned int core;
 346         unsigned int irq;
 347         union cvmx_ciu_wdogx ciu_wdog;
 348         int node;
 349         struct irq_domain *domain;
 350         int hwirq;
 351
 352         core = cpu2core(cpu);
 353         node = cpu_to_node(cpu);
 354
 355         octeon_wdt_bootvector[core].target_ptr = (u64)octeon_wdt_nmi_stage2;
 356
 357         /* Disable it before doing anything with the interrupts. */
 358         ciu_wdog.u64 = 0;
 359         cvmx_write_csr_node(node, CVMX_CIU_WDOGX(core), ciu_wdog.u64);
 360
 361         per_cpu_countdown[cpu] = countdown_reset;
 362
 363         if (octeon_has_feature(OCTEON_FEATURE_CIU3)) {
 364                 /* Must get the domain for the watchdog block */
 365                 domain = octeon_irq_get_block_domain(node, WD_BLOCK_NUMBER);
 366
 367                 /* Get a irq for the wd intsn (hardware interrupt) */
 368                 hwirq = WD_BLOCK_NUMBER << 12 | 0x200 | core;
 369                 irq = irq_create_mapping(domain, hwirq);
 370                 irqd_set_trigger_type(irq_get_irq_data(irq),
 371                                       IRQ_TYPE_EDGE_RISING);
 372         } else
 373                 irq = OCTEON_IRQ_WDOG0 + core;
 374
 375         if (request_irq(irq, octeon_wdt_poke_irq,
 376                         IRQF_NO_THREAD, "octeon_wdt", octeon_wdt_poke_irq))
 377                 panic("octeon_wdt: Couldn't obtain irq %d", irq);
 378
 379         /* Must set the irq affinity here */
 380         if (octeon_has_feature(OCTEON_FEATURE_CIU3)) {
 381                 cpumask_t mask;
 382
 383                 cpumask_clear(&mask);
 384                 cpumask_set_cpu(cpu, &mask);
 385                 irq_set_affinity(irq, &mask);
 386         }
 387
 388         cpumask_set_cpu(cpu, &irq_enabled_cpus);
 389
 390         /* Poke the watchdog to clear out its state */
 391         cvmx_write_csr_node(node, CVMX_CIU_PP_POKEX(core), 1);
 392
 393         /* Finally enable the watchdog now that all handlers are installed */
 394         ciu_wdog.u64 = 0;
 395         ciu_wdog.s.len = timeout_cnt;
 396         ciu_wdog.s.mode = 3;    /* 3 = Interrupt + NMI + Soft-Reset */
 397         cvmx_write_csr_node(node, CVMX_CIU_WDOGX(core), ciu_wdog.u64);
 398
 399         return 0;
 400 }
 401
 402 static int octeon_wdt_ping(struct watchdog_device __always_unused *wdog)
 403 {
 404         int cpu;
 405         int coreid;
 406         int node;
 407
 408         if (disable)
 409                 return 0;
 410
 411         for_each_online_cpu(cpu) {
 412                 coreid = cpu2core(cpu);
 413                 node = cpu_to_node(cpu);
 414                 cvmx_write_csr_node(node, CVMX_CIU_PP_POKEX(coreid), 1);
 415                 per_cpu_countdown[cpu] = countdown_reset;
 416                 if ((countdown_reset || !do_countdown) &&
 417                     !cpumask_test_cpu(cpu, &irq_enabled_cpus)) {
 418                         /* We have to enable the irq */
 419                         enable_irq(octeon_wdt_cpu_to_irq(cpu));
 420                         cpumask_set_cpu(cpu, &irq_enabled_cpus);
 421                 }
 422         }
 423         return 0;
 424 }
 425
 426 static void octeon_wdt_calc_parameters(int t)
 427 {
 428         unsigned int periods;
 429
 430         timeout_sec = max_timeout_sec;
 431
 432
 433         /*
 434          * Find the largest interrupt period, that can evenly divide
 435          * the requested heartbeat time.
 436          */
 437         while ((t % timeout_sec) != 0)
 438                 timeout_sec--;
 439
 440         periods = t / timeout_sec;
 441
 442         /*
 443          * The last two periods are after the irq is disabled, and
 444          * then to the nmi, so we subtract them off.
 445          */
 446
 447         countdown_reset = periods > 2 ? periods - 2 : 0;
 448         heartbeat = t;
 449         timeout_cnt = ((octeon_get_io_clock_rate() / divisor) * timeout_sec) >> 8;
 450 }
 451
 452 static int octeon_wdt_set_timeout(struct watchdog_device *wdog,
 453                                   unsigned int t)
 454 {
 455         int cpu;
 456         int coreid;
 457         union cvmx_ciu_wdogx ciu_wdog;
 458         int node;
 459
 460         if (t <= 0)
 461                 return -1;
 462
 463         octeon_wdt_calc_parameters(t);
 464
 465         if (disable)
 466                 return 0;
 467
 468         for_each_online_cpu(cpu) {
 469                 coreid = cpu2core(cpu);
 470                 node = cpu_to_node(cpu);
 471                 cvmx_write_csr_node(node, CVMX_CIU_PP_POKEX(coreid), 1);
 472                 ciu_wdog.u64 = 0;
 473                 ciu_wdog.s.len = timeout_cnt;
 474                 ciu_wdog.s.mode = 3;    /* 3 = Interrupt + NMI + Soft-Reset */
 475                 cvmx_write_csr_node(node, CVMX_CIU_WDOGX(coreid), ciu_wdog.u64);
 476                 cvmx_write_csr_node(node, CVMX_CIU_PP_POKEX(coreid), 1);
 477         }
 478         octeon_wdt_ping(wdog); /* Get the irqs back on. */
 479         return 0;
 480 }
 481
 482 static int octeon_wdt_start(struct watchdog_device *wdog)
 483 {
 484         octeon_wdt_ping(wdog);
 485         do_countdown = 1;
 486         return 0;
 487 }
 488
 489 static int octeon_wdt_stop(struct watchdog_device *wdog)
 490 {
 491         do_countdown = 0;
 492         octeon_wdt_ping(wdog);
 493         return 0;
 494 }
 495
 496 static const struct watchdog_info octeon_wdt_info = {
 497         .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 498         .identity = "OCTEON",
 499 };
 500
 501 static const struct watchdog_ops octeon_wdt_ops = {
 502         .owner          = THIS_MODULE,
 503         .start          = octeon_wdt_start,
 504         .stop           = octeon_wdt_stop,
 505         .ping           = octeon_wdt_ping,
 506         .set_timeout    = octeon_wdt_set_timeout,
 507 };
 508
 509 static struct watchdog_device octeon_wdt = {
 510         .info   = &octeon_wdt_info,
 511         .ops    = &octeon_wdt_ops,
 512 };
 513
 514 static enum cpuhp_state octeon_wdt_online;
 515 /**
 516  * Module/ driver initialization.
 517  *
 518  * Returns Zero on success
 519  */
 520 static int __init octeon_wdt_init(void)
 521 {
 522         int ret;
 523
 524         octeon_wdt_bootvector = cvmx_boot_vector_get();
 525         if (!octeon_wdt_bootvector) {
 526                 pr_err("Error: Cannot allocate boot vector.\n");
 527                 return -ENOMEM;
 528         }
 529
 530         if (OCTEON_IS_MODEL(OCTEON_CN68XX))
 531                 divisor = 0x200;
 532         else if (OCTEON_IS_MODEL(OCTEON_CN78XX))
 533                 divisor = 0x400;
 534         else
 535                 divisor = 0x100;
 536
 537         /*
 538          * Watchdog time expiration length = The 16 bits of LEN
 539          * represent the most significant bits of a 24 bit decrementer
 540          * that decrements every divisor cycle.
 541          *
 542          * Try for a timeout of 5 sec, if that fails a smaller number
 543          * of even seconds,
 544          */
 545         max_timeout_sec = 6;
 546         do {
 547                 max_timeout_sec--;
 548                 timeout_cnt = ((octeon_get_io_clock_rate() / divisor) * max_timeout_sec) >> 8;
 549         } while (timeout_cnt > 65535);
 550
 551         BUG_ON(timeout_cnt == 0);
 552
 553         octeon_wdt_calc_parameters(heartbeat);
 554
 555         pr_info("Initial granularity %d Sec\n", timeout_sec);
 556
 557         octeon_wdt.timeout      = timeout_sec;
 558         octeon_wdt.max_timeout  = UINT_MAX;
 559
 560         watchdog_set_nowayout(&octeon_wdt, nowayout);
 561
 562         ret = watchdog_register_device(&octeon_wdt);
 563         if (ret) {
 564                 pr_err("watchdog_register_device() failed: %d\n", ret);
 565                 return ret;
 566         }
 567
 568         if (disable) {
 569                 pr_notice("disabled\n");
 570                 return 0;
 571         }
 572
 573         cpumask_clear(&irq_enabled_cpus);
 574
 575         ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "watchdog/octeon:online",
 576                                 octeon_wdt_cpu_online, octeon_wdt_cpu_pre_down);
 577         if (ret < 0)
 578                 goto err;
 579         octeon_wdt_online = ret;
 580         return 0;
 581 err:
 582         cvmx_write_csr(CVMX_MIO_BOOT_LOC_CFGX(0), 0);
 583         watchdog_unregister_device(&octeon_wdt);
 584         return ret;
 585 }
 586
 587 /**
 588  * Module / driver shutdown
 589  */
 590 static void __exit octeon_wdt_cleanup(void)
 591 {
 592         watchdog_unregister_device(&octeon_wdt);
 593
 594         if (disable)
 595                 return;
 596
 597         cpuhp_remove_state(octeon_wdt_online);
 598
 599         /*
 600          * Disable the boot-bus memory, the code it points to is soon
 601          * to go missing.
 602          */
 603         cvmx_write_csr(CVMX_MIO_BOOT_LOC_CFGX(0), 0);
 604 }
 605
 606 MODULE_LICENSE("GPL");
 607 MODULE_AUTHOR("Cavium Inc. <support@cavium.com>");
 608 MODULE_DESCRIPTION("Cavium Inc. OCTEON Watchdog driver.");
 609 module_init(octeon_wdt_init);
 610 module_exit(octeon_wdt_cleanup);