drivers/sbus/char/bbc_envctrl.c

   1 /* bbc_envctrl.c: UltraSPARC-III environment control driver.
   2  *
   3  * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net)
   4  */
   5
   6 #include <linux/kthread.h>
   7 #include <linux/delay.h>
   8 #include <linux/kmod.h>
   9 #include <linux/reboot.h>
  10 #include <linux/of.h>
  11 #include <linux/slab.h>
  12 #include <linux/of_device.h>
  13 #include <asm/oplib.h>
  14
  15 #include "bbc_i2c.h"
  16 #include "max1617.h"
  17
  18 #undef ENVCTRL_TRACE
  19
  20 /* WARNING: Making changes to this driver is very dangerous.
  21  *          If you misprogram the sensor chips they can
  22  *          cut the power on you instantly.
  23  */
  24
  25 /* Two temperature sensors exist in the SunBLADE-1000 enclosure.
  26  * Both are implemented using max1617 i2c devices.  Each max1617
  27  * monitors 2 temperatures, one for one of the cpu dies and the other
  28  * for the ambient temperature.
  29  *
  30  * The max1617 is capable of being programmed with power-off
  31  * temperature values, one low limit and one high limit.  These
  32  * can be controlled independently for the cpu or ambient temperature.
  33  * If a limit is violated, the power is simply shut off.  The frequency
  34  * with which the max1617 does temperature sampling can be controlled
  35  * as well.
  36  *
  37  * Three fans exist inside the machine, all three are controlled with
  38  * an i2c digital to analog converter.  There is a fan directed at the
  39  * two processor slots, another for the rest of the enclosure, and the
  40  * third is for the power supply.  The first two fans may be speed
  41  * controlled by changing the voltage fed to them.  The third fan may
  42  * only be completely off or on.  The third fan is meant to only be
  43  * disabled/enabled when entering/exiting the lowest power-saving
  44  * mode of the machine.
  45  *
  46  * An environmental control kernel thread periodically monitors all
  47  * temperature sensors.  Based upon the samples it will adjust the
  48  * fan speeds to try and keep the system within a certain temperature
  49  * range (the goal being to make the fans as quiet as possible without
  50  * allowing the system to get too hot).
  51  *
  52  * If the temperature begins to rise/fall outside of the acceptable
  53  * operating range, a periodic warning will be sent to the kernel log.
  54  * The fans will be put on full blast to attempt to deal with this
  55  * situation.  After exceeding the acceptable operating range by a
  56  * certain threshold, the kernel thread will shut down the system.
  57  * Here, the thread is attempting to shut the machine down cleanly
  58  * before the hardware based power-off event is triggered.
  59  */
  60
  61 /* These settings are in Celsius.  We use these defaults only
  62  * if we cannot interrogate the cpu-fru SEEPROM.
  63  */
  64 struct temp_limits {
  65         s8 high_pwroff, high_shutdown, high_warn;
  66         s8 low_warn, low_shutdown, low_pwroff;
  67 };
  68
  69 static struct temp_limits cpu_temp_limits[2] = {
  70         { 100, 85, 80, 5, -5, -10 },
  71         { 100, 85, 80, 5, -5, -10 },
  72 };
  73
  74 static struct temp_limits amb_temp_limits[2] = {
  75         { 65, 55, 40, 5, -5, -10 },
  76         { 65, 55, 40, 5, -5, -10 },
  77 };
  78
  79 static LIST_HEAD(all_temps);
  80 static LIST_HEAD(all_fans);
  81
  82 #define CPU_FAN_REG     0xf0
  83 #define SYS_FAN_REG     0xf2
  84 #define PSUPPLY_FAN_REG 0xf4
  85
  86 #define FAN_SPEED_MIN   0x0c
  87 #define FAN_SPEED_MAX   0x3f
  88
  89 #define PSUPPLY_FAN_ON  0x1f
  90 #define PSUPPLY_FAN_OFF 0x00
  91
  92 static void set_fan_speeds(struct bbc_fan_control *fp)
  93 {
  94         /* Put temperatures into range so we don't mis-program
  95          * the hardware.
  96          */
  97         if (fp->cpu_fan_speed < FAN_SPEED_MIN)
  98                 fp->cpu_fan_speed = FAN_SPEED_MIN;
  99         if (fp->cpu_fan_speed > FAN_SPEED_MAX)
 100                 fp->cpu_fan_speed = FAN_SPEED_MAX;
 101         if (fp->system_fan_speed < FAN_SPEED_MIN)
 102                 fp->system_fan_speed = FAN_SPEED_MIN;
 103         if (fp->system_fan_speed > FAN_SPEED_MAX)
 104                 fp->system_fan_speed = FAN_SPEED_MAX;
 105 #ifdef ENVCTRL_TRACE
 106         printk("fan%d: Changed fan speed to cpu(%02x) sys(%02x)\n",
 107                fp->index,
 108                fp->cpu_fan_speed, fp->system_fan_speed);
 109 #endif
 110
 111         bbc_i2c_writeb(fp->client, fp->cpu_fan_speed, CPU_FAN_REG);
 112         bbc_i2c_writeb(fp->client, fp->system_fan_speed, SYS_FAN_REG);
 113         bbc_i2c_writeb(fp->client,
 114                        (fp->psupply_fan_on ?
 115                         PSUPPLY_FAN_ON : PSUPPLY_FAN_OFF),
 116                        PSUPPLY_FAN_REG);
 117 }
 118
 119 static void get_current_temps(struct bbc_cpu_temperature *tp)
 120 {
 121         tp->prev_amb_temp = tp->curr_amb_temp;
 122         bbc_i2c_readb(tp->client,
 123                       (unsigned char *) &tp->curr_amb_temp,
 124                       MAX1617_AMB_TEMP);
 125         tp->prev_cpu_temp = tp->curr_cpu_temp;
 126         bbc_i2c_readb(tp->client,
 127                       (unsigned char *) &tp->curr_cpu_temp,
 128                       MAX1617_CPU_TEMP);
 129 #ifdef ENVCTRL_TRACE
 130         printk("temp%d: cpu(%d C) amb(%d C)\n",
 131                tp->index,
 132                (int) tp->curr_cpu_temp, (int) tp->curr_amb_temp);
 133 #endif
 134 }
 135
 136
 137 static void do_envctrl_shutdown(struct bbc_cpu_temperature *tp)
 138 {
 139         static int shutting_down = 0;
 140         char *type = "???";
 141         s8 val = -1;
 142
 143         if (shutting_down != 0)
 144                 return;
 145
 146         if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_shutdown ||
 147             tp->curr_amb_temp < amb_temp_limits[tp->index].low_shutdown) {
 148                 type = "ambient";
 149                 val = tp->curr_amb_temp;
 150         } else if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_shutdown ||
 151                    tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_shutdown) {
 152                 type = "CPU";
 153                 val = tp->curr_cpu_temp;
 154         }
 155
 156         printk(KERN_CRIT "temp%d: Outside of safe %s "
 157                "operating temperature, %d C.\n",
 158                tp->index, type, val);
 159
 160         printk(KERN_CRIT "kenvctrld: Shutting down the system now.\n");
 161
 162         shutting_down = 1;
 163         orderly_poweroff(true);
 164 }
 165
 166 #define WARN_INTERVAL   (30 * HZ)
 167
 168 static void analyze_ambient_temp(struct bbc_cpu_temperature *tp, unsigned long *last_warn, int tick)
 169 {
 170         int ret = 0;
 171
 172         if (time_after(jiffies, (*last_warn + WARN_INTERVAL))) {
 173                 if (tp->curr_amb_temp >=
 174                     amb_temp_limits[tp->index].high_warn) {
 175                         printk(KERN_WARNING "temp%d: "
 176                                "Above safe ambient operating temperature, %d C.\n",
 177                                tp->index, (int) tp->curr_amb_temp);
 178                         ret = 1;
 179                 } else if (tp->curr_amb_temp <
 180                            amb_temp_limits[tp->index].low_warn) {
 181                         printk(KERN_WARNING "temp%d: "
 182                                "Below safe ambient operating temperature, %d C.\n",
 183                                tp->index, (int) tp->curr_amb_temp);
 184                         ret = 1;
 185                 }
 186                 if (ret)
 187                         *last_warn = jiffies;
 188         } else if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_warn ||
 189                    tp->curr_amb_temp < amb_temp_limits[tp->index].low_warn)
 190                 ret = 1;
 191
 192         /* Now check the shutdown limits. */
 193         if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_shutdown ||
 194             tp->curr_amb_temp < amb_temp_limits[tp->index].low_shutdown) {
 195                 do_envctrl_shutdown(tp);
 196                 ret = 1;
 197         }
 198
 199         if (ret) {
 200                 tp->fan_todo[FAN_AMBIENT] = FAN_FULLBLAST;
 201         } else if ((tick & (8 - 1)) == 0) {
 202                 s8 amb_goal_hi = amb_temp_limits[tp->index].high_warn - 10;
 203                 s8 amb_goal_lo;
 204
 205                 amb_goal_lo = amb_goal_hi - 3;
 206
 207                 /* We do not try to avoid 'too cold' events.  Basically we
 208                  * only try to deal with over-heating and fan noise reduction.
 209                  */
 210                 if (tp->avg_amb_temp < amb_goal_hi) {
 211                         if (tp->avg_amb_temp >= amb_goal_lo)
 212                                 tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
 213                         else
 214                                 tp->fan_todo[FAN_AMBIENT] = FAN_SLOWER;
 215                 } else {
 216                         tp->fan_todo[FAN_AMBIENT] = FAN_FASTER;
 217                 }
 218         } else {
 219                 tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
 220         }
 221 }
 222
 223 static void analyze_cpu_temp(struct bbc_cpu_temperature *tp, unsigned long *last_warn, int tick)
 224 {
 225         int ret = 0;
 226
 227         if (time_after(jiffies, (*last_warn + WARN_INTERVAL))) {
 228                 if (tp->curr_cpu_temp >=
 229                     cpu_temp_limits[tp->index].high_warn) {
 230                         printk(KERN_WARNING "temp%d: "
 231                                "Above safe CPU operating temperature, %d C.\n",
 232                                tp->index, (int) tp->curr_cpu_temp);
 233                         ret = 1;
 234                 } else if (tp->curr_cpu_temp <
 235                            cpu_temp_limits[tp->index].low_warn) {
 236                         printk(KERN_WARNING "temp%d: "
 237                                "Below safe CPU operating temperature, %d C.\n",
 238                                tp->index, (int) tp->curr_cpu_temp);
 239                         ret = 1;
 240                 }
 241                 if (ret)
 242                         *last_warn = jiffies;
 243         } else if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_warn ||
 244                    tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_warn)
 245                 ret = 1;
 246
 247         /* Now check the shutdown limits. */
 248         if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_shutdown ||
 249             tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_shutdown) {
 250                 do_envctrl_shutdown(tp);
 251                 ret = 1;
 252         }
 253
 254         if (ret) {
 255                 tp->fan_todo[FAN_CPU] = FAN_FULLBLAST;
 256         } else if ((tick & (8 - 1)) == 0) {
 257                 s8 cpu_goal_hi = cpu_temp_limits[tp->index].high_warn - 10;
 258                 s8 cpu_goal_lo;
 259
 260                 cpu_goal_lo = cpu_goal_hi - 3;
 261
 262                 /* We do not try to avoid 'too cold' events.  Basically we
 263                  * only try to deal with over-heating and fan noise reduction.
 264                  */
 265                 if (tp->avg_cpu_temp < cpu_goal_hi) {
 266                         if (tp->avg_cpu_temp >= cpu_goal_lo)
 267                                 tp->fan_todo[FAN_CPU] = FAN_SAME;
 268                         else
 269                                 tp->fan_todo[FAN_CPU] = FAN_SLOWER;
 270                 } else {
 271                         tp->fan_todo[FAN_CPU] = FAN_FASTER;
 272                 }
 273         } else {
 274                 tp->fan_todo[FAN_CPU] = FAN_SAME;
 275         }
 276 }
 277
 278 static void analyze_temps(struct bbc_cpu_temperature *tp, unsigned long *last_warn)
 279 {
 280         tp->avg_amb_temp = (s8)((int)((int)tp->avg_amb_temp + (int)tp->curr_amb_temp) / 2);
 281         tp->avg_cpu_temp = (s8)((int)((int)tp->avg_cpu_temp + (int)tp->curr_cpu_temp) / 2);
 282
 283         analyze_ambient_temp(tp, last_warn, tp->sample_tick);
 284         analyze_cpu_temp(tp, last_warn, tp->sample_tick);
 285
 286         tp->sample_tick++;
 287 }
 288
 289 static enum fan_action prioritize_fan_action(int which_fan)
 290 {
 291         struct bbc_cpu_temperature *tp;
 292         enum fan_action decision = FAN_STATE_MAX;
 293
 294         /* Basically, prioritize what the temperature sensors
 295          * recommend we do, and perform that action on all the
 296          * fans.
 297          */
 298         list_for_each_entry(tp, &all_temps, glob_list) {
 299                 if (tp->fan_todo[which_fan] == FAN_FULLBLAST) {
 300                         decision = FAN_FULLBLAST;
 301                         break;
 302                 }
 303                 if (tp->fan_todo[which_fan] == FAN_SAME &&
 304                     decision != FAN_FASTER)
 305                         decision = FAN_SAME;
 306                 else if (tp->fan_todo[which_fan] == FAN_FASTER)
 307                         decision = FAN_FASTER;
 308                 else if (decision != FAN_FASTER &&
 309                          decision != FAN_SAME &&
 310                          tp->fan_todo[which_fan] == FAN_SLOWER)
 311                         decision = FAN_SLOWER;
 312         }
 313         if (decision == FAN_STATE_MAX)
 314                 decision = FAN_SAME;
 315
 316         return decision;
 317 }
 318
 319 static int maybe_new_ambient_fan_speed(struct bbc_fan_control *fp)
 320 {
 321         enum fan_action decision = prioritize_fan_action(FAN_AMBIENT);
 322         int ret;
 323
 324         if (decision == FAN_SAME)
 325                 return 0;
 326
 327         ret = 1;
 328         if (decision == FAN_FULLBLAST) {
 329                 if (fp->system_fan_speed >= FAN_SPEED_MAX)
 330                         ret = 0;
 331                 else
 332                         fp->system_fan_speed = FAN_SPEED_MAX;
 333         } else {
 334                 if (decision == FAN_FASTER) {
 335                         if (fp->system_fan_speed >= FAN_SPEED_MAX)
 336                                 ret = 0;
 337                         else
 338                                 fp->system_fan_speed += 2;
 339                 } else {
 340                         int orig_speed = fp->system_fan_speed;
 341
 342                         if (orig_speed <= FAN_SPEED_MIN ||
 343                             orig_speed <= (fp->cpu_fan_speed - 3))
 344                                 ret = 0;
 345                         else
 346                                 fp->system_fan_speed -= 1;
 347                 }
 348         }
 349
 350         return ret;
 351 }
 352
 353 static int maybe_new_cpu_fan_speed(struct bbc_fan_control *fp)
 354 {
 355         enum fan_action decision = prioritize_fan_action(FAN_CPU);
 356         int ret;
 357
 358         if (decision == FAN_SAME)
 359                 return 0;
 360
 361         ret = 1;
 362         if (decision == FAN_FULLBLAST) {
 363                 if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
 364                         ret = 0;
 365                 else
 366                         fp->cpu_fan_speed = FAN_SPEED_MAX;
 367         } else {
 368                 if (decision == FAN_FASTER) {
 369                         if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
 370                                 ret = 0;
 371                         else {
 372                                 fp->cpu_fan_speed += 2;
 373                                 if (fp->system_fan_speed <
 374                                     (fp->cpu_fan_speed - 3))
 375                                         fp->system_fan_speed =
 376                                                 fp->cpu_fan_speed - 3;
 377                         }
 378                 } else {
 379                         if (fp->cpu_fan_speed <= FAN_SPEED_MIN)
 380                                 ret = 0;
 381                         else
 382                                 fp->cpu_fan_speed -= 1;
 383                 }
 384         }
 385
 386         return ret;
 387 }
 388
 389 static void maybe_new_fan_speeds(struct bbc_fan_control *fp)
 390 {
 391         int new;
 392
 393         new  = maybe_new_ambient_fan_speed(fp);
 394         new |= maybe_new_cpu_fan_speed(fp);
 395
 396         if (new)
 397                 set_fan_speeds(fp);
 398 }
 399
 400 static void fans_full_blast(void)
 401 {
 402         struct bbc_fan_control *fp;
 403
 404         /* Since we will not be monitoring things anymore, put
 405          * the fans on full blast.
 406          */
 407         list_for_each_entry(fp, &all_fans, glob_list) {
 408                 fp->cpu_fan_speed = FAN_SPEED_MAX;
 409                 fp->system_fan_speed = FAN_SPEED_MAX;
 410                 fp->psupply_fan_on = 1;
 411                 set_fan_speeds(fp);
 412         }
 413 }
 414
 415 #define POLL_INTERVAL   (5 * 1000)
 416 static unsigned long last_warning_jiffies;
 417 static struct task_struct *kenvctrld_task;
 418
 419 static int kenvctrld(void *__unused)
 420 {
 421         printk(KERN_INFO "bbc_envctrl: kenvctrld starting...\n");
 422         last_warning_jiffies = jiffies - WARN_INTERVAL;
 423         for (;;) {
 424                 struct bbc_cpu_temperature *tp;
 425                 struct bbc_fan_control *fp;
 426
 427                 msleep_interruptible(POLL_INTERVAL);
 428                 if (kthread_should_stop())
 429                         break;
 430
 431                 list_for_each_entry(tp, &all_temps, glob_list) {
 432                         get_current_temps(tp);
 433                         analyze_temps(tp, &last_warning_jiffies);
 434                 }
 435                 list_for_each_entry(fp, &all_fans, glob_list)
 436                         maybe_new_fan_speeds(fp);
 437         }
 438         printk(KERN_INFO "bbc_envctrl: kenvctrld exiting...\n");
 439
 440         fans_full_blast();
 441
 442         return 0;
 443 }
 444
 445 static void attach_one_temp(struct bbc_i2c_bus *bp, struct platform_device *op,
 446                             int temp_idx)
 447 {
 448         struct bbc_cpu_temperature *tp;
 449
 450         tp = kzalloc(sizeof(*tp), GFP_KERNEL);
 451         if (!tp)
 452                 return;
 453
 454         INIT_LIST_HEAD(&tp->bp_list);
 455         INIT_LIST_HEAD(&tp->glob_list);
 456
 457         tp->client = bbc_i2c_attach(bp, op);
 458         if (!tp->client) {
 459                 kfree(tp);
 460                 return;
 461         }
 462
 463
 464         tp->index = temp_idx;
 465
 466         list_add(&tp->glob_list, &all_temps);
 467         list_add(&tp->bp_list, &bp->temps);
 468
 469         /* Tell it to convert once every 5 seconds, clear all cfg
 470          * bits.
 471          */
 472         bbc_i2c_writeb(tp->client, 0x00, MAX1617_WR_CFG_BYTE);
 473         bbc_i2c_writeb(tp->client, 0x02, MAX1617_WR_CVRATE_BYTE);
 474
 475         /* Program the hard temperature limits into the chip. */
 476         bbc_i2c_writeb(tp->client, amb_temp_limits[tp->index].high_pwroff,
 477                        MAX1617_WR_AMB_HIGHLIM);
 478         bbc_i2c_writeb(tp->client, amb_temp_limits[tp->index].low_pwroff,
 479                        MAX1617_WR_AMB_LOWLIM);
 480         bbc_i2c_writeb(tp->client, cpu_temp_limits[tp->index].high_pwroff,
 481                        MAX1617_WR_CPU_HIGHLIM);
 482         bbc_i2c_writeb(tp->client, cpu_temp_limits[tp->index].low_pwroff,
 483                        MAX1617_WR_CPU_LOWLIM);
 484
 485         get_current_temps(tp);
 486         tp->prev_cpu_temp = tp->avg_cpu_temp = tp->curr_cpu_temp;
 487         tp->prev_amb_temp = tp->avg_amb_temp = tp->curr_amb_temp;
 488
 489         tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
 490         tp->fan_todo[FAN_CPU] = FAN_SAME;
 491 }
 492
 493 static void attach_one_fan(struct bbc_i2c_bus *bp, struct platform_device *op,
 494                            int fan_idx)
 495 {
 496         struct bbc_fan_control *fp;
 497
 498         fp = kzalloc(sizeof(*fp), GFP_KERNEL);
 499         if (!fp)
 500                 return;
 501
 502         INIT_LIST_HEAD(&fp->bp_list);
 503         INIT_LIST_HEAD(&fp->glob_list);
 504
 505         fp->client = bbc_i2c_attach(bp, op);
 506         if (!fp->client) {
 507                 kfree(fp);
 508                 return;
 509         }
 510
 511         fp->index = fan_idx;
 512
 513         list_add(&fp->glob_list, &all_fans);
 514         list_add(&fp->bp_list, &bp->fans);
 515
 516         /* The i2c device controlling the fans is write-only.
 517          * So the only way to keep track of the current power
 518          * level fed to the fans is via software.  Choose half
 519          * power for cpu/system and 'on' fo the powersupply fan
 520          * and set it now.
 521          */
 522         fp->psupply_fan_on = 1;
 523         fp->cpu_fan_speed = (FAN_SPEED_MAX - FAN_SPEED_MIN) / 2;
 524         fp->cpu_fan_speed += FAN_SPEED_MIN;
 525         fp->system_fan_speed = (FAN_SPEED_MAX - FAN_SPEED_MIN) / 2;
 526         fp->system_fan_speed += FAN_SPEED_MIN;
 527
 528         set_fan_speeds(fp);
 529 }
 530
 531 static void destroy_one_temp(struct bbc_cpu_temperature *tp)
 532 {
 533         bbc_i2c_detach(tp->client);
 534         kfree(tp);
 535 }
 536
 537 static void destroy_all_temps(struct bbc_i2c_bus *bp)
 538 {
 539         struct bbc_cpu_temperature *tp, *tpos;
 540
 541         list_for_each_entry_safe(tp, tpos, &bp->temps, bp_list) {
 542                 list_del(&tp->bp_list);
 543                 list_del(&tp->glob_list);
 544                 destroy_one_temp(tp);
 545         }
 546 }
 547
 548 static void destroy_one_fan(struct bbc_fan_control *fp)
 549 {
 550         bbc_i2c_detach(fp->client);
 551         kfree(fp);
 552 }
 553
 554 static void destroy_all_fans(struct bbc_i2c_bus *bp)
 555 {
 556         struct bbc_fan_control *fp, *fpos;
 557
 558         list_for_each_entry_safe(fp, fpos, &bp->fans, bp_list) {
 559                 list_del(&fp->bp_list);
 560                 list_del(&fp->glob_list);
 561                 destroy_one_fan(fp);
 562         }
 563 }
 564
 565 int bbc_envctrl_init(struct bbc_i2c_bus *bp)
 566 {
 567         struct platform_device *op;
 568         int temp_index = 0;
 569         int fan_index = 0;
 570         int devidx = 0;
 571
 572         while ((op = bbc_i2c_getdev(bp, devidx++)) != NULL) {
 573                 if (!strcmp(op->dev.of_node->name, "temperature"))
 574                         attach_one_temp(bp, op, temp_index++);
 575                 if (!strcmp(op->dev.of_node->name, "fan-control"))
 576                         attach_one_fan(bp, op, fan_index++);
 577         }
 578         if (temp_index != 0 && fan_index != 0) {
 579                 kenvctrld_task = kthread_run(kenvctrld, NULL, "kenvctrld");
 580                 if (IS_ERR(kenvctrld_task)) {
 581                         int err = PTR_ERR(kenvctrld_task);
 582
 583                         kenvctrld_task = NULL;
 584                         destroy_all_temps(bp);
 585                         destroy_all_fans(bp);
 586                         return err;
 587                 }
 588         }
 589
 590         return 0;
 591 }
 592
 593 void bbc_envctrl_cleanup(struct bbc_i2c_bus *bp)
 594 {
 595         if (kenvctrld_task)
 596                 kthread_stop(kenvctrld_task);
 597
 598         destroy_all_temps(bp);
 599         destroy_all_fans(bp);
 600 }