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 #include <linux/kernel.h>
   8 #include <linux/sched.h>
   9 #include <linux/slab.h>
  10 #include <linux/delay.h>
  11 #include <asm/oplib.h>
  12 #include <asm/ebus.h>
  13 #define __KERNEL_SYSCALLS__
  14 static int errno;
  15 #include <asm/unistd.h>
  16
  17 #include "bbc_i2c.h"
  18 #include "max1617.h"
  19
  20 #undef ENVCTRL_TRACE
  21
  22 /* WARNING: Making changes to this driver is very dangerous.
  23  *          If you misprogram the sensor chips they can
  24  *          cut the power on you instantly.
  25  */
  26
  27 /* Two temperature sensors exist in the SunBLADE-1000 enclosure.
  28  * Both are implemented using max1617 i2c devices.  Each max1617
  29  * monitors 2 temperatures, one for one of the cpu dies and the other
  30  * for the ambient temperature.
  31  *
  32  * The max1617 is capable of being programmed with power-off
  33  * temperature values, one low limit and one high limit.  These
  34  * can be controlled independently for the cpu or ambient temperature.
  35  * If a limit is violated, the power is simply shut off.  The frequency
  36  * with which the max1617 does temperature sampling can be controlled
  37  * as well.
  38  *
  39  * Three fans exist inside the machine, all three are controlled with
  40  * an i2c digital to analog converter.  There is a fan directed at the
  41  * two processor slots, another for the rest of the enclosure, and the
  42  * third is for the power supply.  The first two fans may be speed
  43  * controlled by changing the voltage fed to them.  The third fan may
  44  * only be completely off or on.  The third fan is meant to only be
  45  * disabled/enabled when entering/exiting the lowest power-saving
  46  * mode of the machine.
  47  *
  48  * An environmental control kernel thread periodically monitors all
  49  * temperature sensors.  Based upon the samples it will adjust the
  50  * fan speeds to try and keep the system within a certain temperature
  51  * range (the goal being to make the fans as quiet as possible without
  52  * allowing the system to get too hot).
  53  *
  54  * If the temperature begins to rise/fall outside of the acceptable
  55  * operating range, a periodic warning will be sent to the kernel log.
  56  * The fans will be put on full blast to attempt to deal with this
  57  * situation.  After exceeding the acceptable operating range by a
  58  * certain threshold, the kernel thread will shut down the system.
  59  * Here, the thread is attempting to shut the machine down cleanly
  60  * before the hardware based power-off event is triggered.
  61  */
  62
  63 /* These settings are in Celsius.  We use these defaults only
  64  * if we cannot interrogate the cpu-fru SEEPROM.
  65  */
  66 struct temp_limits {
  67         s8 high_pwroff, high_shutdown, high_warn;
  68         s8 low_warn, low_shutdown, low_pwroff;
  69 };
  70
  71 static struct temp_limits cpu_temp_limits[2] = {
  72         { 100, 85, 80, 5, -5, -10 },
  73         { 100, 85, 80, 5, -5, -10 },
  74 };
  75
  76 static struct temp_limits amb_temp_limits[2] = {
  77         { 65, 55, 40, 5, -5, -10 },
  78         { 65, 55, 40, 5, -5, -10 },
  79 };
  80
  81 enum fan_action { FAN_SLOWER, FAN_SAME, FAN_FASTER, FAN_FULLBLAST, FAN_STATE_MAX };
  82
  83 struct bbc_cpu_temperature {
  84         struct bbc_cpu_temperature      *next;
  85
  86         struct bbc_i2c_client           *client;
  87         int                             index;
  88
  89         /* Current readings, and history. */
  90         s8                              curr_cpu_temp;
  91         s8                              curr_amb_temp;
  92         s8                              prev_cpu_temp;
  93         s8                              prev_amb_temp;
  94         s8                              avg_cpu_temp;
  95         s8                              avg_amb_temp;
  96
  97         int                             sample_tick;
  98
  99         enum fan_action                 fan_todo[2];
 100 #define FAN_AMBIENT     0
 101 #define FAN_CPU         1
 102 };
 103
 104 struct bbc_cpu_temperature *all_bbc_temps;
 105
 106 struct bbc_fan_control {
 107         struct bbc_fan_control  *next;
 108
 109         struct bbc_i2c_client   *client;
 110         int                     index;
 111
 112         int                     psupply_fan_on;
 113         int                     cpu_fan_speed;
 114         int                     system_fan_speed;
 115 };
 116
 117 struct bbc_fan_control *all_bbc_fans;
 118
 119 #define CPU_FAN_REG     0xf0
 120 #define SYS_FAN_REG     0xf2
 121 #define PSUPPLY_FAN_REG 0xf4
 122
 123 #define FAN_SPEED_MIN   0x0c
 124 #define FAN_SPEED_MAX   0x3f
 125
 126 #define PSUPPLY_FAN_ON  0x1f
 127 #define PSUPPLY_FAN_OFF 0x00
 128
 129 static void set_fan_speeds(struct bbc_fan_control *fp)
 130 {
 131         /* Put temperatures into range so we don't mis-program
 132          * the hardware.
 133          */
 134         if (fp->cpu_fan_speed < FAN_SPEED_MIN)
 135                 fp->cpu_fan_speed = FAN_SPEED_MIN;
 136         if (fp->cpu_fan_speed > FAN_SPEED_MAX)
 137                 fp->cpu_fan_speed = FAN_SPEED_MAX;
 138         if (fp->system_fan_speed < FAN_SPEED_MIN)
 139                 fp->system_fan_speed = FAN_SPEED_MIN;
 140         if (fp->system_fan_speed > FAN_SPEED_MAX)
 141                 fp->system_fan_speed = FAN_SPEED_MAX;
 142 #ifdef ENVCTRL_TRACE
 143         printk("fan%d: Changed fan speed to cpu(%02x) sys(%02x)\n",
 144                fp->index,
 145                fp->cpu_fan_speed, fp->system_fan_speed);
 146 #endif
 147
 148         bbc_i2c_writeb(fp->client, fp->cpu_fan_speed, CPU_FAN_REG);
 149         bbc_i2c_writeb(fp->client, fp->system_fan_speed, SYS_FAN_REG);
 150         bbc_i2c_writeb(fp->client,
 151                        (fp->psupply_fan_on ?
 152                         PSUPPLY_FAN_ON : PSUPPLY_FAN_OFF),
 153                        PSUPPLY_FAN_REG);
 154 }
 155
 156 static void get_current_temps(struct bbc_cpu_temperature *tp)
 157 {
 158         tp->prev_amb_temp = tp->curr_amb_temp;
 159         bbc_i2c_readb(tp->client,
 160                       (unsigned char *) &tp->curr_amb_temp,
 161                       MAX1617_AMB_TEMP);
 162         tp->prev_cpu_temp = tp->curr_cpu_temp;
 163         bbc_i2c_readb(tp->client,
 164                       (unsigned char *) &tp->curr_cpu_temp,
 165                       MAX1617_CPU_TEMP);
 166 #ifdef ENVCTRL_TRACE
 167         printk("temp%d: cpu(%d C) amb(%d C)\n",
 168                tp->index,
 169                (int) tp->curr_cpu_temp, (int) tp->curr_amb_temp);
 170 #endif
 171 }
 172
 173
 174 static void do_envctrl_shutdown(struct bbc_cpu_temperature *tp)
 175 {
 176         static int shutting_down = 0;
 177         static char *envp[] = { "HOME=/", "TERM=linux", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL };
 178         char *argv[] = { "/sbin/shutdown", "-h", "now", NULL };
 179         char *type = "???";
 180         s8 val = -1;
 181
 182         if (shutting_down != 0)
 183                 return;
 184
 185         if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_shutdown ||
 186             tp->curr_amb_temp < amb_temp_limits[tp->index].low_shutdown) {
 187                 type = "ambient";
 188                 val = tp->curr_amb_temp;
 189         } else if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_shutdown ||
 190                    tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_shutdown) {
 191                 type = "CPU";
 192                 val = tp->curr_cpu_temp;
 193         }
 194
 195         printk(KERN_CRIT "temp%d: Outside of safe %s "
 196                "operating temperature, %d C.\n",
 197                tp->index, type, val);
 198
 199         printk(KERN_CRIT "kenvctrld: Shutting down the system now.\n");
 200
 201         shutting_down = 1;
 202         if (execve("/sbin/shutdown", argv, envp) < 0)
 203                 printk(KERN_CRIT "envctrl: shutdown execution failed\n");
 204 }
 205
 206 #define WARN_INTERVAL   (30 * HZ)
 207
 208 static void analyze_ambient_temp(struct bbc_cpu_temperature *tp, unsigned long *last_warn, int tick)
 209 {
 210         int ret = 0;
 211
 212         if (time_after(jiffies, (*last_warn + WARN_INTERVAL))) {
 213                 if (tp->curr_amb_temp >=
 214                     amb_temp_limits[tp->index].high_warn) {
 215                         printk(KERN_WARNING "temp%d: "
 216                                "Above safe ambient operating temperature, %d C.\n",
 217                                tp->index, (int) tp->curr_amb_temp);
 218                         ret = 1;
 219                 } else if (tp->curr_amb_temp <
 220                            amb_temp_limits[tp->index].low_warn) {
 221                         printk(KERN_WARNING "temp%d: "
 222                                "Below safe ambient operating temperature, %d C.\n",
 223                                tp->index, (int) tp->curr_amb_temp);
 224                         ret = 1;
 225                 }
 226                 if (ret)
 227                         *last_warn = jiffies;
 228         } else if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_warn ||
 229                    tp->curr_amb_temp < amb_temp_limits[tp->index].low_warn)
 230                 ret = 1;
 231
 232         /* Now check the shutdown limits. */
 233         if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_shutdown ||
 234             tp->curr_amb_temp < amb_temp_limits[tp->index].low_shutdown) {
 235                 do_envctrl_shutdown(tp);
 236                 ret = 1;
 237         }
 238
 239         if (ret) {
 240                 tp->fan_todo[FAN_AMBIENT] = FAN_FULLBLAST;
 241         } else if ((tick & (8 - 1)) == 0) {
 242                 s8 amb_goal_hi = amb_temp_limits[tp->index].high_warn - 10;
 243                 s8 amb_goal_lo;
 244
 245                 amb_goal_lo = amb_goal_hi - 3;
 246
 247                 /* We do not try to avoid 'too cold' events.  Basically we
 248                  * only try to deal with over-heating and fan noise reduction.
 249                  */
 250                 if (tp->avg_amb_temp < amb_goal_hi) {
 251                         if (tp->avg_amb_temp >= amb_goal_lo)
 252                                 tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
 253                         else
 254                                 tp->fan_todo[FAN_AMBIENT] = FAN_SLOWER;
 255                 } else {
 256                         tp->fan_todo[FAN_AMBIENT] = FAN_FASTER;
 257                 }
 258         } else {
 259                 tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
 260         }
 261 }
 262
 263 static void analyze_cpu_temp(struct bbc_cpu_temperature *tp, unsigned long *last_warn, int tick)
 264 {
 265         int ret = 0;
 266
 267         if (time_after(jiffies, (*last_warn + WARN_INTERVAL))) {
 268                 if (tp->curr_cpu_temp >=
 269                     cpu_temp_limits[tp->index].high_warn) {
 270                         printk(KERN_WARNING "temp%d: "
 271                                "Above safe CPU operating temperature, %d C.\n",
 272                                tp->index, (int) tp->curr_cpu_temp);
 273                         ret = 1;
 274                 } else if (tp->curr_cpu_temp <
 275                            cpu_temp_limits[tp->index].low_warn) {
 276                         printk(KERN_WARNING "temp%d: "
 277                                "Below safe CPU operating temperature, %d C.\n",
 278                                tp->index, (int) tp->curr_cpu_temp);
 279                         ret = 1;
 280                 }
 281                 if (ret)
 282                         *last_warn = jiffies;
 283         } else if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_warn ||
 284                    tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_warn)
 285                 ret = 1;
 286
 287         /* Now check the shutdown limits. */
 288         if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_shutdown ||
 289             tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_shutdown) {
 290                 do_envctrl_shutdown(tp);
 291                 ret = 1;
 292         }
 293
 294         if (ret) {
 295                 tp->fan_todo[FAN_CPU] = FAN_FULLBLAST;
 296         } else if ((tick & (8 - 1)) == 0) {
 297                 s8 cpu_goal_hi = cpu_temp_limits[tp->index].high_warn - 10;
 298                 s8 cpu_goal_lo;
 299
 300                 cpu_goal_lo = cpu_goal_hi - 3;
 301
 302                 /* We do not try to avoid 'too cold' events.  Basically we
 303                  * only try to deal with over-heating and fan noise reduction.
 304                  */
 305                 if (tp->avg_cpu_temp < cpu_goal_hi) {
 306                         if (tp->avg_cpu_temp >= cpu_goal_lo)
 307                                 tp->fan_todo[FAN_CPU] = FAN_SAME;
 308                         else
 309                                 tp->fan_todo[FAN_CPU] = FAN_SLOWER;
 310                 } else {
 311                         tp->fan_todo[FAN_CPU] = FAN_FASTER;
 312                 }
 313         } else {
 314                 tp->fan_todo[FAN_CPU] = FAN_SAME;
 315         }
 316 }
 317
 318 static void analyze_temps(struct bbc_cpu_temperature *tp, unsigned long *last_warn)
 319 {
 320         tp->avg_amb_temp = (s8)((int)((int)tp->avg_amb_temp + (int)tp->curr_amb_temp) / 2);
 321         tp->avg_cpu_temp = (s8)((int)((int)tp->avg_cpu_temp + (int)tp->curr_cpu_temp) / 2);
 322
 323         analyze_ambient_temp(tp, last_warn, tp->sample_tick);
 324         analyze_cpu_temp(tp, last_warn, tp->sample_tick);
 325
 326         tp->sample_tick++;
 327 }
 328
 329 static enum fan_action prioritize_fan_action(int which_fan)
 330 {
 331         struct bbc_cpu_temperature *tp;
 332         enum fan_action decision = FAN_STATE_MAX;
 333
 334         /* Basically, prioritize what the temperature sensors
 335          * recommend we do, and perform that action on all the
 336          * fans.
 337          */
 338         for (tp = all_bbc_temps; tp; tp = tp->next) {
 339                 if (tp->fan_todo[which_fan] == FAN_FULLBLAST) {
 340                         decision = FAN_FULLBLAST;
 341                         break;
 342                 }
 343                 if (tp->fan_todo[which_fan] == FAN_SAME &&
 344                     decision != FAN_FASTER)
 345                         decision = FAN_SAME;
 346                 else if (tp->fan_todo[which_fan] == FAN_FASTER)
 347                         decision = FAN_FASTER;
 348                 else if (decision != FAN_FASTER &&
 349                          decision != FAN_SAME &&
 350                          tp->fan_todo[which_fan] == FAN_SLOWER)
 351                         decision = FAN_SLOWER;
 352         }
 353         if (decision == FAN_STATE_MAX)
 354                 decision = FAN_SAME;
 355
 356         return decision;
 357 }
 358
 359 static int maybe_new_ambient_fan_speed(struct bbc_fan_control *fp)
 360 {
 361         enum fan_action decision = prioritize_fan_action(FAN_AMBIENT);
 362         int ret;
 363
 364         if (decision == FAN_SAME)
 365                 return 0;
 366
 367         ret = 1;
 368         if (decision == FAN_FULLBLAST) {
 369                 if (fp->system_fan_speed >= FAN_SPEED_MAX)
 370                         ret = 0;
 371                 else
 372                         fp->system_fan_speed = FAN_SPEED_MAX;
 373         } else {
 374                 if (decision == FAN_FASTER) {
 375                         if (fp->system_fan_speed >= FAN_SPEED_MAX)
 376                                 ret = 0;
 377                         else
 378                                 fp->system_fan_speed += 2;
 379                 } else {
 380                         int orig_speed = fp->system_fan_speed;
 381
 382                         if (orig_speed <= FAN_SPEED_MIN ||
 383                             orig_speed <= (fp->cpu_fan_speed - 3))
 384                                 ret = 0;
 385                         else
 386                                 fp->system_fan_speed -= 1;
 387                 }
 388         }
 389
 390         return ret;
 391 }
 392
 393 static int maybe_new_cpu_fan_speed(struct bbc_fan_control *fp)
 394 {
 395         enum fan_action decision = prioritize_fan_action(FAN_CPU);
 396         int ret;
 397
 398         if (decision == FAN_SAME)
 399                 return 0;
 400
 401         ret = 1;
 402         if (decision == FAN_FULLBLAST) {
 403                 if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
 404                         ret = 0;
 405                 else
 406                         fp->cpu_fan_speed = FAN_SPEED_MAX;
 407         } else {
 408                 if (decision == FAN_FASTER) {
 409                         if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
 410                                 ret = 0;
 411                         else {
 412                                 fp->cpu_fan_speed += 2;
 413                                 if (fp->system_fan_speed <
 414                                     (fp->cpu_fan_speed - 3))
 415                                         fp->system_fan_speed =
 416                                                 fp->cpu_fan_speed - 3;
 417                         }
 418                 } else {
 419                         if (fp->cpu_fan_speed <= FAN_SPEED_MIN)
 420                                 ret = 0;
 421                         else
 422                                 fp->cpu_fan_speed -= 1;
 423                 }
 424         }
 425
 426         return ret;
 427 }
 428
 429 static void maybe_new_fan_speeds(struct bbc_fan_control *fp)
 430 {
 431         int new;
 432
 433         new  = maybe_new_ambient_fan_speed(fp);
 434         new |= maybe_new_cpu_fan_speed(fp);
 435
 436         if (new)
 437                 set_fan_speeds(fp);
 438 }
 439
 440 static void fans_full_blast(void)
 441 {
 442         struct bbc_fan_control *fp;
 443
 444         /* Since we will not be monitoring things anymore, put
 445          * the fans on full blast.
 446          */
 447         for (fp = all_bbc_fans; fp; fp = fp->next) {
 448                 fp->cpu_fan_speed = FAN_SPEED_MAX;
 449                 fp->system_fan_speed = FAN_SPEED_MAX;
 450                 fp->psupply_fan_on = 1;
 451                 set_fan_speeds(fp);
 452         }
 453 }
 454
 455 #define POLL_INTERVAL   (5 * 1000)
 456 static unsigned long last_warning_jiffies;
 457 static struct task_struct *kenvctrld_task;
 458
 459 static int kenvctrld(void *__unused)
 460 {
 461         daemonize("kenvctrld");
 462         allow_signal(SIGKILL);
 463         kenvctrld_task = current;
 464
 465         printk(KERN_INFO "bbc_envctrl: kenvctrld starting...\n");
 466         last_warning_jiffies = jiffies - WARN_INTERVAL;
 467         for (;;) {
 468                 struct bbc_cpu_temperature *tp;
 469                 struct bbc_fan_control *fp;
 470
 471                 msleep_interruptible(POLL_INTERVAL);
 472                 if (signal_pending(current))
 473                         break;
 474
 475                 for (tp = all_bbc_temps; tp; tp = tp->next) {
 476                         get_current_temps(tp);
 477                         analyze_temps(tp, &last_warning_jiffies);
 478                 }
 479                 for (fp = all_bbc_fans; fp; fp = fp->next)
 480                         maybe_new_fan_speeds(fp);
 481         }
 482         printk(KERN_INFO "bbc_envctrl: kenvctrld exiting...\n");
 483
 484         fans_full_blast();
 485
 486         return 0;
 487 }
 488
 489 static void attach_one_temp(struct linux_ebus_child *echild, int temp_idx)
 490 {
 491         struct bbc_cpu_temperature *tp = kmalloc(sizeof(*tp), GFP_KERNEL);
 492
 493         if (!tp)
 494                 return;
 495         memset(tp, 0, sizeof(*tp));
 496         tp->client = bbc_i2c_attach(echild);
 497         if (!tp->client) {
 498                 kfree(tp);
 499                 return;
 500         }
 501
 502         tp->index = temp_idx;
 503         {
 504                 struct bbc_cpu_temperature **tpp = &all_bbc_temps;
 505                 while (*tpp)
 506                         tpp = &((*tpp)->next);
 507                 tp->next = NULL;
 508                 *tpp = tp;
 509         }
 510
 511         /* Tell it to convert once every 5 seconds, clear all cfg
 512          * bits.
 513          */
 514         bbc_i2c_writeb(tp->client, 0x00, MAX1617_WR_CFG_BYTE);
 515         bbc_i2c_writeb(tp->client, 0x02, MAX1617_WR_CVRATE_BYTE);
 516
 517         /* Program the hard temperature limits into the chip. */
 518         bbc_i2c_writeb(tp->client, amb_temp_limits[tp->index].high_pwroff,
 519                        MAX1617_WR_AMB_HIGHLIM);
 520         bbc_i2c_writeb(tp->client, amb_temp_limits[tp->index].low_pwroff,
 521                        MAX1617_WR_AMB_LOWLIM);
 522         bbc_i2c_writeb(tp->client, cpu_temp_limits[tp->index].high_pwroff,
 523                        MAX1617_WR_CPU_HIGHLIM);
 524         bbc_i2c_writeb(tp->client, cpu_temp_limits[tp->index].low_pwroff,
 525                        MAX1617_WR_CPU_LOWLIM);
 526
 527         get_current_temps(tp);
 528         tp->prev_cpu_temp = tp->avg_cpu_temp = tp->curr_cpu_temp;
 529         tp->prev_amb_temp = tp->avg_amb_temp = tp->curr_amb_temp;
 530
 531         tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
 532         tp->fan_todo[FAN_CPU] = FAN_SAME;
 533 }
 534
 535 static void attach_one_fan(struct linux_ebus_child *echild, int fan_idx)
 536 {
 537         struct bbc_fan_control *fp = kmalloc(sizeof(*fp), GFP_KERNEL);
 538
 539         if (!fp)
 540                 return;
 541         memset(fp, 0, sizeof(*fp));
 542         fp->client = bbc_i2c_attach(echild);
 543         if (!fp->client) {
 544                 kfree(fp);
 545                 return;
 546         }
 547
 548         fp->index = fan_idx;
 549
 550         {
 551                 struct bbc_fan_control **fpp = &all_bbc_fans;
 552                 while (*fpp)
 553                         fpp = &((*fpp)->next);
 554                 fp->next = NULL;
 555                 *fpp = fp;
 556         }
 557
 558         /* The i2c device controlling the fans is write-only.
 559          * So the only way to keep track of the current power
 560          * level fed to the fans is via software.  Choose half
 561          * power for cpu/system and 'on' fo the powersupply fan
 562          * and set it now.
 563          */
 564         fp->psupply_fan_on = 1;
 565         fp->cpu_fan_speed = (FAN_SPEED_MAX - FAN_SPEED_MIN) / 2;
 566         fp->cpu_fan_speed += FAN_SPEED_MIN;
 567         fp->system_fan_speed = (FAN_SPEED_MAX - FAN_SPEED_MIN) / 2;
 568         fp->system_fan_speed += FAN_SPEED_MIN;
 569
 570         set_fan_speeds(fp);
 571 }
 572
 573 int bbc_envctrl_init(void)
 574 {
 575         struct linux_ebus_child *echild;
 576         int temp_index = 0;
 577         int fan_index = 0;
 578         int devidx = 0;
 579         int err = 0;
 580
 581         while ((echild = bbc_i2c_getdev(devidx++)) != NULL) {
 582                 if (!strcmp(echild->prom_name, "temperature"))
 583                         attach_one_temp(echild, temp_index++);
 584                 if (!strcmp(echild->prom_name, "fan-control"))
 585                         attach_one_fan(echild, fan_index++);
 586         }
 587         if (temp_index != 0 && fan_index != 0)
 588                 err = kernel_thread(kenvctrld, NULL, CLONE_FS | CLONE_FILES);
 589         return err;
 590 }
 591
 592 static void destroy_one_temp(struct bbc_cpu_temperature *tp)
 593 {
 594         bbc_i2c_detach(tp->client);
 595         kfree(tp);
 596 }
 597
 598 static void destroy_one_fan(struct bbc_fan_control *fp)
 599 {
 600         bbc_i2c_detach(fp->client);
 601         kfree(fp);
 602 }
 603
 604 void bbc_envctrl_cleanup(void)
 605 {
 606         struct bbc_cpu_temperature *tp;
 607         struct bbc_fan_control *fp;
 608
 609         if (kenvctrld_task != NULL) {
 610                 force_sig(SIGKILL, kenvctrld_task);
 611                 for (;;) {
 612                         struct task_struct *p;
 613                         int found = 0;
 614
 615                         read_lock(&tasklist_lock);
 616                         for_each_process(p) {
 617                                 if (p == kenvctrld_task) {
 618                                         found = 1;
 619                                         break;
 620                                 }
 621                         }
 622                         read_unlock(&tasklist_lock);
 623                         if (!found)
 624                                 break;
 625                         msleep(1000);
 626                 }
 627                 kenvctrld_task = NULL;
 628         }
 629
 630         tp = all_bbc_temps;
 631         while (tp != NULL) {
 632                 struct bbc_cpu_temperature *next = tp->next;
 633                 destroy_one_temp(tp);
 634                 tp = next;
 635         }
 636         all_bbc_temps = NULL;
 637
 638         fp = all_bbc_fans;
 639         while (fp != NULL) {
 640                 struct bbc_fan_control *next = fp->next;
 641                 destroy_one_fan(fp);
 642                 fp = next;
 643         }
 644         all_bbc_fans = NULL;
 645 }