drivers/sbus/char/bbc_envctrl.c

   1 /* $Id: bbc_envctrl.c,v 1.4 2001/04/06 16:48:08 davem Exp $
   2  * bbc_envctrl.c: UltraSPARC-III environment control driver.
   3  *
   4  * Copyright (C) 2001 David S. Miller (davem@redhat.com)
   5  */
   6
   7 #define __KERNEL_SYSCALLS__
   8
   9 #include <linux/kernel.h>
  10 #include <linux/kthread.h>
  11 #include <linux/sched.h>
  12 #include <linux/slab.h>
  13 #include <linux/delay.h>
  14 #include <asm/oplib.h>
  15 #include <asm/ebus.h>
  16 static int errno;
  17 #include <asm/unistd.h>
  18
  19 #include "bbc_i2c.h"
  20 #include "max1617.h"
  21
  22 #undef ENVCTRL_TRACE
  23
  24 /* WARNING: Making changes to this driver is very dangerous.
  25  *          If you misprogram the sensor chips they can
  26  *          cut the power on you instantly.
  27  */
  28
  29 /* Two temperature sensors exist in the SunBLADE-1000 enclosure.
  30  * Both are implemented using max1617 i2c devices.  Each max1617
  31  * monitors 2 temperatures, one for one of the cpu dies and the other
  32  * for the ambient temperature.
  33  *
  34  * The max1617 is capable of being programmed with power-off
  35  * temperature values, one low limit and one high limit.  These
  36  * can be controlled independently for the cpu or ambient temperature.
  37  * If a limit is violated, the power is simply shut off.  The frequency
  38  * with which the max1617 does temperature sampling can be controlled
  39  * as well.
  40  *
  41  * Three fans exist inside the machine, all three are controlled with
  42  * an i2c digital to analog converter.  There is a fan directed at the
  43  * two processor slots, another for the rest of the enclosure, and the
  44  * third is for the power supply.  The first two fans may be speed
  45  * controlled by changing the voltage fed to them.  The third fan may
  46  * only be completely off or on.  The third fan is meant to only be
  47  * disabled/enabled when entering/exiting the lowest power-saving
  48  * mode of the machine.
  49  *
  50  * An environmental control kernel thread periodically monitors all
  51  * temperature sensors.  Based upon the samples it will adjust the
  52  * fan speeds to try and keep the system within a certain temperature
  53  * range (the goal being to make the fans as quiet as possible without
  54  * allowing the system to get too hot).
  55  *
  56  * If the temperature begins to rise/fall outside of the acceptable
  57  * operating range, a periodic warning will be sent to the kernel log.
  58  * The fans will be put on full blast to attempt to deal with this
  59  * situation.  After exceeding the acceptable operating range by a
  60  * certain threshold, the kernel thread will shut down the system.
  61  * Here, the thread is attempting to shut the machine down cleanly
  62  * before the hardware based power-off event is triggered.
  63  */
  64
  65 /* These settings are in Celsius.  We use these defaults only
  66  * if we cannot interrogate the cpu-fru SEEPROM.
  67  */
  68 struct temp_limits {
  69         s8 high_pwroff, high_shutdown, high_warn;
  70         s8 low_warn, low_shutdown, low_pwroff;
  71 };
  72
  73 static struct temp_limits cpu_temp_limits[2] = {
  74         { 100, 85, 80, 5, -5, -10 },
  75         { 100, 85, 80, 5, -5, -10 },
  76 };
  77
  78 static struct temp_limits amb_temp_limits[2] = {
  79         { 65, 55, 40, 5, -5, -10 },
  80         { 65, 55, 40, 5, -5, -10 },
  81 };
  82
  83 enum fan_action { FAN_SLOWER, FAN_SAME, FAN_FASTER, FAN_FULLBLAST, FAN_STATE_MAX };
  84
  85 struct bbc_cpu_temperature {
  86         struct bbc_cpu_temperature      *next;
  87
  88         struct bbc_i2c_client           *client;
  89         int                             index;
  90
  91         /* Current readings, and history. */
  92         s8                              curr_cpu_temp;
  93         s8                              curr_amb_temp;
  94         s8                              prev_cpu_temp;
  95         s8                              prev_amb_temp;
  96         s8                              avg_cpu_temp;
  97         s8                              avg_amb_temp;
  98
  99         int                             sample_tick;
 100
 101         enum fan_action                 fan_todo[2];
 102 #define FAN_AMBIENT     0
 103 #define FAN_CPU         1
 104 };
 105
 106 struct bbc_cpu_temperature *all_bbc_temps;
 107
 108 struct bbc_fan_control {
 109         struct bbc_fan_control  *next;
 110
 111         struct bbc_i2c_client   *client;
 112         int                     index;
 113
 114         int                     psupply_fan_on;
 115         int                     cpu_fan_speed;
 116         int                     system_fan_speed;
 117 };
 118
 119 struct bbc_fan_control *all_bbc_fans;
 120
 121 #define CPU_FAN_REG     0xf0
 122 #define SYS_FAN_REG     0xf2
 123 #define PSUPPLY_FAN_REG 0xf4
 124
 125 #define FAN_SPEED_MIN   0x0c
 126 #define FAN_SPEED_MAX   0x3f
 127
 128 #define PSUPPLY_FAN_ON  0x1f
 129 #define PSUPPLY_FAN_OFF 0x00
 130
 131 static void set_fan_speeds(struct bbc_fan_control *fp)
 132 {
 133         /* Put temperatures into range so we don't mis-program
 134          * the hardware.
 135          */
 136         if (fp->cpu_fan_speed < FAN_SPEED_MIN)
 137                 fp->cpu_fan_speed = FAN_SPEED_MIN;
 138         if (fp->cpu_fan_speed > FAN_SPEED_MAX)
 139                 fp->cpu_fan_speed = FAN_SPEED_MAX;
 140         if (fp->system_fan_speed < FAN_SPEED_MIN)
 141                 fp->system_fan_speed = FAN_SPEED_MIN;
 142         if (fp->system_fan_speed > FAN_SPEED_MAX)
 143                 fp->system_fan_speed = FAN_SPEED_MAX;
 144 #ifdef ENVCTRL_TRACE
 145         printk("fan%d: Changed fan speed to cpu(%02x) sys(%02x)\n",
 146                fp->index,
 147                fp->cpu_fan_speed, fp->system_fan_speed);
 148 #endif
 149
 150         bbc_i2c_writeb(fp->client, fp->cpu_fan_speed, CPU_FAN_REG);
 151         bbc_i2c_writeb(fp->client, fp->system_fan_speed, SYS_FAN_REG);
 152         bbc_i2c_writeb(fp->client,
 153                        (fp->psupply_fan_on ?
 154                         PSUPPLY_FAN_ON : PSUPPLY_FAN_OFF),
 155                        PSUPPLY_FAN_REG);
 156 }
 157
 158 static void get_current_temps(struct bbc_cpu_temperature *tp)
 159 {
 160         tp->prev_amb_temp = tp->curr_amb_temp;
 161         bbc_i2c_readb(tp->client,
 162                       (unsigned char *) &tp->curr_amb_temp,
 163                       MAX1617_AMB_TEMP);
 164         tp->prev_cpu_temp = tp->curr_cpu_temp;
 165         bbc_i2c_readb(tp->client,
 166                       (unsigned char *) &tp->curr_cpu_temp,
 167                       MAX1617_CPU_TEMP);
 168 #ifdef ENVCTRL_TRACE
 169         printk("temp%d: cpu(%d C) amb(%d C)\n",
 170                tp->index,
 171                (int) tp->curr_cpu_temp, (int) tp->curr_amb_temp);
 172 #endif
 173 }
 174
 175
 176 static void do_envctrl_shutdown(struct bbc_cpu_temperature *tp)
 177 {
 178         static int shutting_down = 0;
 179         static char *envp[] = { "HOME=/", "TERM=linux", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL };
 180         char *argv[] = { "/sbin/shutdown", "-h", "now", NULL };
 181         char *type = "???";
 182         s8 val = -1;
 183
 184         if (shutting_down != 0)
 185                 return;
 186
 187         if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_shutdown ||
 188             tp->curr_amb_temp < amb_temp_limits[tp->index].low_shutdown) {
 189                 type = "ambient";
 190                 val = tp->curr_amb_temp;
 191         } else if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_shutdown ||
 192                    tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_shutdown) {
 193                 type = "CPU";
 194                 val = tp->curr_cpu_temp;
 195         }
 196
 197         printk(KERN_CRIT "temp%d: Outside of safe %s "
 198                "operating temperature, %d C.\n",
 199                tp->index, type, val);
 200
 201         printk(KERN_CRIT "kenvctrld: Shutting down the system now.\n");
 202
 203         shutting_down = 1;
 204         if (execve("/sbin/shutdown", argv, envp) < 0)
 205                 printk(KERN_CRIT "envctrl: shutdown execution failed\n");
 206 }
 207
 208 #define WARN_INTERVAL   (30 * HZ)
 209
 210 static void analyze_ambient_temp(struct bbc_cpu_temperature *tp, unsigned long *last_warn, int tick)
 211 {
 212         int ret = 0;
 213
 214         if (time_after(jiffies, (*last_warn + WARN_INTERVAL))) {
 215                 if (tp->curr_amb_temp >=
 216                     amb_temp_limits[tp->index].high_warn) {
 217                         printk(KERN_WARNING "temp%d: "
 218                                "Above safe ambient operating temperature, %d C.\n",
 219                                tp->index, (int) tp->curr_amb_temp);
 220                         ret = 1;
 221                 } else if (tp->curr_amb_temp <
 222                            amb_temp_limits[tp->index].low_warn) {
 223                         printk(KERN_WARNING "temp%d: "
 224                                "Below safe ambient operating temperature, %d C.\n",
 225                                tp->index, (int) tp->curr_amb_temp);
 226                         ret = 1;
 227                 }
 228                 if (ret)
 229                         *last_warn = jiffies;
 230         } else if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_warn ||
 231                    tp->curr_amb_temp < amb_temp_limits[tp->index].low_warn)
 232                 ret = 1;
 233
 234         /* Now check the shutdown limits. */
 235         if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_shutdown ||
 236             tp->curr_amb_temp < amb_temp_limits[tp->index].low_shutdown) {
 237                 do_envctrl_shutdown(tp);
 238                 ret = 1;
 239         }
 240
 241         if (ret) {
 242                 tp->fan_todo[FAN_AMBIENT] = FAN_FULLBLAST;
 243         } else if ((tick & (8 - 1)) == 0) {
 244                 s8 amb_goal_hi = amb_temp_limits[tp->index].high_warn - 10;
 245                 s8 amb_goal_lo;
 246
 247                 amb_goal_lo = amb_goal_hi - 3;
 248
 249                 /* We do not try to avoid 'too cold' events.  Basically we
 250                  * only try to deal with over-heating and fan noise reduction.
 251                  */
 252                 if (tp->avg_amb_temp < amb_goal_hi) {
 253                         if (tp->avg_amb_temp >= amb_goal_lo)
 254                                 tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
 255                         else
 256                                 tp->fan_todo[FAN_AMBIENT] = FAN_SLOWER;
 257                 } else {
 258                         tp->fan_todo[FAN_AMBIENT] = FAN_FASTER;
 259                 }
 260         } else {
 261                 tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
 262         }
 263 }
 264
 265 static void analyze_cpu_temp(struct bbc_cpu_temperature *tp, unsigned long *last_warn, int tick)
 266 {
 267         int ret = 0;
 268
 269         if (time_after(jiffies, (*last_warn + WARN_INTERVAL))) {
 270                 if (tp->curr_cpu_temp >=
 271                     cpu_temp_limits[tp->index].high_warn) {
 272                         printk(KERN_WARNING "temp%d: "
 273                                "Above safe CPU operating temperature, %d C.\n",
 274                                tp->index, (int) tp->curr_cpu_temp);
 275                         ret = 1;
 276                 } else if (tp->curr_cpu_temp <
 277                            cpu_temp_limits[tp->index].low_warn) {
 278                         printk(KERN_WARNING "temp%d: "
 279                                "Below safe CPU operating temperature, %d C.\n",
 280                                tp->index, (int) tp->curr_cpu_temp);
 281                         ret = 1;
 282                 }
 283                 if (ret)
 284                         *last_warn = jiffies;
 285         } else if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_warn ||
 286                    tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_warn)
 287                 ret = 1;
 288
 289         /* Now check the shutdown limits. */
 290         if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_shutdown ||
 291             tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_shutdown) {
 292                 do_envctrl_shutdown(tp);
 293                 ret = 1;
 294         }
 295
 296         if (ret) {
 297                 tp->fan_todo[FAN_CPU] = FAN_FULLBLAST;
 298         } else if ((tick & (8 - 1)) == 0) {
 299                 s8 cpu_goal_hi = cpu_temp_limits[tp->index].high_warn - 10;
 300                 s8 cpu_goal_lo;
 301
 302                 cpu_goal_lo = cpu_goal_hi - 3;
 303
 304                 /* We do not try to avoid 'too cold' events.  Basically we
 305                  * only try to deal with over-heating and fan noise reduction.
 306                  */
 307                 if (tp->avg_cpu_temp < cpu_goal_hi) {
 308                         if (tp->avg_cpu_temp >= cpu_goal_lo)
 309                                 tp->fan_todo[FAN_CPU] = FAN_SAME;
 310                         else
 311                                 tp->fan_todo[FAN_CPU] = FAN_SLOWER;
 312                 } else {
 313                         tp->fan_todo[FAN_CPU] = FAN_FASTER;
 314                 }
 315         } else {
 316                 tp->fan_todo[FAN_CPU] = FAN_SAME;
 317         }
 318 }
 319
 320 static void analyze_temps(struct bbc_cpu_temperature *tp, unsigned long *last_warn)
 321 {
 322         tp->avg_amb_temp = (s8)((int)((int)tp->avg_amb_temp + (int)tp->curr_amb_temp) / 2);
 323         tp->avg_cpu_temp = (s8)((int)((int)tp->avg_cpu_temp + (int)tp->curr_cpu_temp) / 2);
 324
 325         analyze_ambient_temp(tp, last_warn, tp->sample_tick);
 326         analyze_cpu_temp(tp, last_warn, tp->sample_tick);
 327
 328         tp->sample_tick++;
 329 }
 330
 331 static enum fan_action prioritize_fan_action(int which_fan)
 332 {
 333         struct bbc_cpu_temperature *tp;
 334         enum fan_action decision = FAN_STATE_MAX;
 335
 336         /* Basically, prioritize what the temperature sensors
 337          * recommend we do, and perform that action on all the
 338          * fans.
 339          */
 340         for (tp = all_bbc_temps; tp; tp = tp->next) {
 341                 if (tp->fan_todo[which_fan] == FAN_FULLBLAST) {
 342                         decision = FAN_FULLBLAST;
 343                         break;
 344                 }
 345                 if (tp->fan_todo[which_fan] == FAN_SAME &&
 346                     decision != FAN_FASTER)
 347                         decision = FAN_SAME;
 348                 else if (tp->fan_todo[which_fan] == FAN_FASTER)
 349                         decision = FAN_FASTER;
 350                 else if (decision != FAN_FASTER &&
 351                          decision != FAN_SAME &&
 352                          tp->fan_todo[which_fan] == FAN_SLOWER)
 353                         decision = FAN_SLOWER;
 354         }
 355         if (decision == FAN_STATE_MAX)
 356                 decision = FAN_SAME;
 357
 358         return decision;
 359 }
 360
 361 static int maybe_new_ambient_fan_speed(struct bbc_fan_control *fp)
 362 {
 363         enum fan_action decision = prioritize_fan_action(FAN_AMBIENT);
 364         int ret;
 365
 366         if (decision == FAN_SAME)
 367                 return 0;
 368
 369         ret = 1;
 370         if (decision == FAN_FULLBLAST) {
 371                 if (fp->system_fan_speed >= FAN_SPEED_MAX)
 372                         ret = 0;
 373                 else
 374                         fp->system_fan_speed = FAN_SPEED_MAX;
 375         } else {
 376                 if (decision == FAN_FASTER) {
 377                         if (fp->system_fan_speed >= FAN_SPEED_MAX)
 378                                 ret = 0;
 379                         else
 380                                 fp->system_fan_speed += 2;
 381                 } else {
 382                         int orig_speed = fp->system_fan_speed;
 383
 384                         if (orig_speed <= FAN_SPEED_MIN ||
 385                             orig_speed <= (fp->cpu_fan_speed - 3))
 386                                 ret = 0;
 387                         else
 388                                 fp->system_fan_speed -= 1;
 389                 }
 390         }
 391
 392         return ret;
 393 }
 394
 395 static int maybe_new_cpu_fan_speed(struct bbc_fan_control *fp)
 396 {
 397         enum fan_action decision = prioritize_fan_action(FAN_CPU);
 398         int ret;
 399
 400         if (decision == FAN_SAME)
 401                 return 0;
 402
 403         ret = 1;
 404         if (decision == FAN_FULLBLAST) {
 405                 if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
 406                         ret = 0;
 407                 else
 408                         fp->cpu_fan_speed = FAN_SPEED_MAX;
 409         } else {
 410                 if (decision == FAN_FASTER) {
 411                         if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
 412                                 ret = 0;
 413                         else {
 414                                 fp->cpu_fan_speed += 2;
 415                                 if (fp->system_fan_speed <
 416                                     (fp->cpu_fan_speed - 3))
 417                                         fp->system_fan_speed =
 418                                                 fp->cpu_fan_speed - 3;
 419                         }
 420                 } else {
 421                         if (fp->cpu_fan_speed <= FAN_SPEED_MIN)
 422                                 ret = 0;
 423                         else
 424                                 fp->cpu_fan_speed -= 1;
 425                 }
 426         }
 427
 428         return ret;
 429 }
 430
 431 static void maybe_new_fan_speeds(struct bbc_fan_control *fp)
 432 {
 433         int new;
 434
 435         new  = maybe_new_ambient_fan_speed(fp);
 436         new |= maybe_new_cpu_fan_speed(fp);
 437
 438         if (new)
 439                 set_fan_speeds(fp);
 440 }
 441
 442 static void fans_full_blast(void)
 443 {
 444         struct bbc_fan_control *fp;
 445
 446         /* Since we will not be monitoring things anymore, put
 447          * the fans on full blast.
 448          */
 449         for (fp = all_bbc_fans; fp; fp = fp->next) {
 450                 fp->cpu_fan_speed = FAN_SPEED_MAX;
 451                 fp->system_fan_speed = FAN_SPEED_MAX;
 452                 fp->psupply_fan_on = 1;
 453                 set_fan_speeds(fp);
 454         }
 455 }
 456
 457 #define POLL_INTERVAL   (5 * 1000)
 458 static unsigned long last_warning_jiffies;
 459 static struct task_struct *kenvctrld_task;
 460
 461 static int kenvctrld(void *__unused)
 462 {
 463         printk(KERN_INFO "bbc_envctrl: kenvctrld starting...\n");
 464         last_warning_jiffies = jiffies - WARN_INTERVAL;
 465         for (;;) {
 466                 struct bbc_cpu_temperature *tp;
 467                 struct bbc_fan_control *fp;
 468
 469                 msleep_interruptible(POLL_INTERVAL);
 470                 if (kthread_should_stop())
 471                         break;
 472
 473                 for (tp = all_bbc_temps; tp; tp = tp->next) {
 474                         get_current_temps(tp);
 475                         analyze_temps(tp, &last_warning_jiffies);
 476                 }
 477                 for (fp = all_bbc_fans; fp; fp = fp->next)
 478                         maybe_new_fan_speeds(fp);
 479         }
 480         printk(KERN_INFO "bbc_envctrl: kenvctrld exiting...\n");
 481
 482         fans_full_blast();
 483
 484         return 0;
 485 }
 486
 487 static void attach_one_temp(struct linux_ebus_child *echild, int temp_idx)
 488 {
 489         struct bbc_cpu_temperature *tp = kmalloc(sizeof(*tp), GFP_KERNEL);
 490
 491         if (!tp)
 492                 return;
 493         memset(tp, 0, sizeof(*tp));
 494         tp->client = bbc_i2c_attach(echild);
 495         if (!tp->client) {
 496                 kfree(tp);
 497                 return;
 498         }
 499
 500         tp->index = temp_idx;
 501         {
 502                 struct bbc_cpu_temperature **tpp = &all_bbc_temps;
 503                 while (*tpp)
 504                         tpp = &((*tpp)->next);
 505                 tp->next = NULL;
 506                 *tpp = tp;
 507         }
 508
 509         /* Tell it to convert once every 5 seconds, clear all cfg
 510          * bits.
 511          */
 512         bbc_i2c_writeb(tp->client, 0x00, MAX1617_WR_CFG_BYTE);
 513         bbc_i2c_writeb(tp->client, 0x02, MAX1617_WR_CVRATE_BYTE);
 514
 515         /* Program the hard temperature limits into the chip. */
 516         bbc_i2c_writeb(tp->client, amb_temp_limits[tp->index].high_pwroff,
 517                        MAX1617_WR_AMB_HIGHLIM);
 518         bbc_i2c_writeb(tp->client, amb_temp_limits[tp->index].low_pwroff,
 519                        MAX1617_WR_AMB_LOWLIM);
 520         bbc_i2c_writeb(tp->client, cpu_temp_limits[tp->index].high_pwroff,
 521                        MAX1617_WR_CPU_HIGHLIM);
 522         bbc_i2c_writeb(tp->client, cpu_temp_limits[tp->index].low_pwroff,
 523                        MAX1617_WR_CPU_LOWLIM);
 524
 525         get_current_temps(tp);
 526         tp->prev_cpu_temp = tp->avg_cpu_temp = tp->curr_cpu_temp;
 527         tp->prev_amb_temp = tp->avg_amb_temp = tp->curr_amb_temp;
 528
 529         tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
 530         tp->fan_todo[FAN_CPU] = FAN_SAME;
 531 }
 532
 533 static void attach_one_fan(struct linux_ebus_child *echild, int fan_idx)
 534 {
 535         struct bbc_fan_control *fp = kmalloc(sizeof(*fp), GFP_KERNEL);
 536
 537         if (!fp)
 538                 return;
 539         memset(fp, 0, sizeof(*fp));
 540         fp->client = bbc_i2c_attach(echild);
 541         if (!fp->client) {
 542                 kfree(fp);
 543                 return;
 544         }
 545
 546         fp->index = fan_idx;
 547
 548         {
 549                 struct bbc_fan_control **fpp = &all_bbc_fans;
 550                 while (*fpp)
 551                         fpp = &((*fpp)->next);
 552                 fp->next = NULL;
 553                 *fpp = fp;
 554         }
 555
 556         /* The i2c device controlling the fans is write-only.
 557          * So the only way to keep track of the current power
 558          * level fed to the fans is via software.  Choose half
 559          * power for cpu/system and 'on' fo the powersupply fan
 560          * and set it now.
 561          */
 562         fp->psupply_fan_on = 1;
 563         fp->cpu_fan_speed = (FAN_SPEED_MAX - FAN_SPEED_MIN) / 2;
 564         fp->cpu_fan_speed += FAN_SPEED_MIN;
 565         fp->system_fan_speed = (FAN_SPEED_MAX - FAN_SPEED_MIN) / 2;
 566         fp->system_fan_speed += FAN_SPEED_MIN;
 567
 568         set_fan_speeds(fp);
 569 }
 570
 571 int bbc_envctrl_init(void)
 572 {
 573         struct linux_ebus_child *echild;
 574         int temp_index = 0;
 575         int fan_index = 0;
 576         int devidx = 0;
 577
 578         while ((echild = bbc_i2c_getdev(devidx++)) != NULL) {
 579                 if (!strcmp(echild->prom_name, "temperature"))
 580                         attach_one_temp(echild, temp_index++);
 581                 if (!strcmp(echild->prom_name, "fan-control"))
 582                         attach_one_fan(echild, fan_index++);
 583         }
 584         if (temp_index != 0 && fan_index != 0) {
 585                 kenvctrld_task = kthread_run(kenvctrld, NULL, "kenvctrld");
 586                 if (IS_ERR(kenvctrld_task))
 587                         return PTR_ERR(kenvctrld_task);
 588         }
 589
 590         return 0;
 591 }
 592
 593 static void destroy_one_temp(struct bbc_cpu_temperature *tp)
 594 {
 595         bbc_i2c_detach(tp->client);
 596         kfree(tp);
 597 }
 598
 599 static void destroy_one_fan(struct bbc_fan_control *fp)
 600 {
 601         bbc_i2c_detach(fp->client);
 602         kfree(fp);
 603 }
 604
 605 void bbc_envctrl_cleanup(void)
 606 {
 607         struct bbc_cpu_temperature *tp;
 608         struct bbc_fan_control *fp;
 609
 610         kthread_stop(kenvctrld_task);
 611
 612         tp = all_bbc_temps;
 613         while (tp != NULL) {
 614                 struct bbc_cpu_temperature *next = tp->next;
 615                 destroy_one_temp(tp);
 616                 tp = next;
 617         }
 618         all_bbc_temps = NULL;
 619
 620         fp = all_bbc_fans;
 621         while (fp != NULL) {
 622                 struct bbc_fan_control *next = fp->next;
 623                 destroy_one_fan(fp);
 624                 fp = next;
 625         }
 626         all_bbc_fans = NULL;
 627 }