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