header cleaning: don't include smp_lock.h when not used
[linux-3.10.git] / drivers / macintosh / therm_adt746x.c
1 /*
2  * Device driver for the i2c thermostat found on the iBook G4, Albook G4
3  *
4  * Copyright (C) 2003, 2004 Colin Leroy, Rasmus Rohde, Benjamin Herrenschmidt
5  *
6  * Documentation from
7  * http://www.analog.com/UploadedFiles/Data_Sheets/115254175ADT7467_pra.pdf
8  * http://www.analog.com/UploadedFiles/Data_Sheets/3686221171167ADT7460_b.pdf
9  *
10  */
11
12 #include <linux/types.h>
13 #include <linux/module.h>
14 #include <linux/errno.h>
15 #include <linux/kernel.h>
16 #include <linux/delay.h>
17 #include <linux/sched.h>
18 #include <linux/i2c.h>
19 #include <linux/slab.h>
20 #include <linux/init.h>
21 #include <linux/spinlock.h>
22 #include <linux/wait.h>
23 #include <linux/suspend.h>
24 #include <linux/kthread.h>
25 #include <linux/moduleparam.h>
26 #include <linux/freezer.h>
27
28 #include <asm/prom.h>
29 #include <asm/machdep.h>
30 #include <asm/io.h>
31 #include <asm/system.h>
32 #include <asm/sections.h>
33 #include <asm/of_platform.h>
34
35 #undef DEBUG
36
37 #define CONFIG_REG   0x40
38 #define MANUAL_MASK  0xe0
39 #define AUTO_MASK    0x20
40
41 static u8 TEMP_REG[3]    = {0x26, 0x25, 0x27}; /* local, sensor1, sensor2 */
42 static u8 LIMIT_REG[3]   = {0x6b, 0x6a, 0x6c}; /* local, sensor1, sensor2 */
43 static u8 MANUAL_MODE[2] = {0x5c, 0x5d};       
44 static u8 REM_CONTROL[2] = {0x00, 0x40};
45 static u8 FAN_SPEED[2]   = {0x28, 0x2a};
46 static u8 FAN_SPD_SET[2] = {0x30, 0x31};
47
48 static u8 default_limits_local[3] = {70, 50, 70};    /* local, sensor1, sensor2 */
49 static u8 default_limits_chip[3] = {80, 65, 80};    /* local, sensor1, sensor2 */
50 static const char *sensor_location[3];
51
52 static int limit_adjust;
53 static int fan_speed = -1;
54 static int verbose;
55
56 MODULE_AUTHOR("Colin Leroy <colin@colino.net>");
57 MODULE_DESCRIPTION("Driver for ADT746x thermostat in iBook G4 and "
58                    "Powerbook G4 Alu");
59 MODULE_LICENSE("GPL");
60
61 module_param(limit_adjust, int, 0644);
62 MODULE_PARM_DESC(limit_adjust,"Adjust maximum temperatures (50 sensor1, 70 sensor2) "
63                  "by N degrees.");
64
65 module_param(fan_speed, int, 0644);
66 MODULE_PARM_DESC(fan_speed,"Specify starting fan speed (0-255) "
67                  "(default 64)");
68
69 module_param(verbose, bool, 0);
70 MODULE_PARM_DESC(verbose,"Verbose log operations "
71                  "(default 0)");
72
73 struct thermostat {
74         struct i2c_client       clt;
75         u8                      temps[3];
76         u8                      cached_temp[3];
77         u8                      initial_limits[3];
78         u8                      limits[3];
79         int                     last_speed[2];
80         int                     last_var[2];
81 };
82
83 static enum {ADT7460, ADT7467} therm_type;
84 static int therm_bus, therm_address;
85 static struct of_device * of_dev;
86 static struct thermostat* thermostat;
87 static struct task_struct *thread_therm = NULL;
88
89 static int attach_one_thermostat(struct i2c_adapter *adapter, int addr,
90                                  int busno);
91
92 static void write_both_fan_speed(struct thermostat *th, int speed);
93 static void write_fan_speed(struct thermostat *th, int speed, int fan);
94
95 static int
96 write_reg(struct thermostat* th, int reg, u8 data)
97 {
98         u8 tmp[2];
99         int rc;
100         
101         tmp[0] = reg;
102         tmp[1] = data;
103         rc = i2c_master_send(&th->clt, (const char *)tmp, 2);
104         if (rc < 0)
105                 return rc;
106         if (rc != 2)
107                 return -ENODEV;
108         return 0;
109 }
110
111 static int
112 read_reg(struct thermostat* th, int reg)
113 {
114         u8 reg_addr, data;
115         int rc;
116
117         reg_addr = (u8)reg;
118         rc = i2c_master_send(&th->clt, &reg_addr, 1);
119         if (rc < 0)
120                 return rc;
121         if (rc != 1)
122                 return -ENODEV;
123         rc = i2c_master_recv(&th->clt, (char *)&data, 1);
124         if (rc < 0)
125                 return rc;
126         return data;
127 }
128
129 static int
130 attach_thermostat(struct i2c_adapter *adapter)
131 {
132         unsigned long bus_no;
133
134         if (strncmp(adapter->name, "uni-n", 5))
135                 return -ENODEV;
136         bus_no = simple_strtoul(adapter->name + 6, NULL, 10);
137         if (bus_no != therm_bus)
138                 return -ENODEV;
139         return attach_one_thermostat(adapter, therm_address, bus_no);
140 }
141
142 static int
143 detach_thermostat(struct i2c_adapter *adapter)
144 {
145         struct thermostat* th;
146         int i;
147         
148         if (thermostat == NULL)
149                 return 0;
150
151         th = thermostat;
152
153         if (thread_therm != NULL) {
154                 kthread_stop(thread_therm);
155         }
156
157         printk(KERN_INFO "adt746x: Putting max temperatures back from "
158                          "%d, %d, %d to %d, %d, %d\n",
159                 th->limits[0], th->limits[1], th->limits[2],
160                 th->initial_limits[0], th->initial_limits[1],
161                 th->initial_limits[2]);
162
163         for (i = 0; i < 3; i++)
164                 write_reg(th, LIMIT_REG[i], th->initial_limits[i]);
165
166         write_both_fan_speed(th, -1);
167
168         i2c_detach_client(&th->clt);
169
170         thermostat = NULL;
171
172         kfree(th);
173
174         return 0;
175 }
176
177 static struct i2c_driver thermostat_driver = {  
178         .driver = {
179                 .name   = "therm_adt746x",
180         },
181         .attach_adapter = attach_thermostat,
182         .detach_adapter = detach_thermostat,
183 };
184
185 static int read_fan_speed(struct thermostat *th, u8 addr)
186 {
187         u8 tmp[2];
188         u16 res;
189         
190         /* should start with low byte */
191         tmp[1] = read_reg(th, addr);
192         tmp[0] = read_reg(th, addr + 1);
193         
194         res = tmp[1] + (tmp[0] << 8);
195         /* "a value of 0xffff means that the fan has stopped" */
196         return (res == 0xffff ? 0 : (90000*60)/res);
197 }
198
199 static void write_both_fan_speed(struct thermostat *th, int speed)
200 {
201         write_fan_speed(th, speed, 0);
202         if (therm_type == ADT7460)
203                 write_fan_speed(th, speed, 1);
204 }
205
206 static void write_fan_speed(struct thermostat *th, int speed, int fan)
207 {
208         u8 manual;
209         
210         if (speed > 0xff) 
211                 speed = 0xff;
212         else if (speed < -1) 
213                 speed = 0;
214         
215         if (therm_type == ADT7467 && fan == 1)
216                 return;
217         
218         if (th->last_speed[fan] != speed) {
219                 if (verbose) {
220                         if (speed == -1)
221                                 printk(KERN_DEBUG "adt746x: Setting speed to automatic "
222                                         "for %s fan.\n", sensor_location[fan+1]);
223                         else
224                                 printk(KERN_DEBUG "adt746x: Setting speed to %d "
225                                         "for %s fan.\n", speed, sensor_location[fan+1]);
226                 }
227         } else
228                 return;
229         
230         if (speed >= 0) {
231                 manual = read_reg(th, MANUAL_MODE[fan]);
232                 write_reg(th, MANUAL_MODE[fan], manual|MANUAL_MASK);
233                 write_reg(th, FAN_SPD_SET[fan], speed);
234         } else {
235                 /* back to automatic */
236                 if(therm_type == ADT7460) {
237                         manual = read_reg(th,
238                                 MANUAL_MODE[fan]) & (~MANUAL_MASK);
239
240                         write_reg(th,
241                                 MANUAL_MODE[fan], manual|REM_CONTROL[fan]);
242                 } else {
243                         manual = read_reg(th, MANUAL_MODE[fan]);
244                         write_reg(th, MANUAL_MODE[fan], manual&(~AUTO_MASK));
245                 }
246         }
247         
248         th->last_speed[fan] = speed;                    
249 }
250
251 static void read_sensors(struct thermostat *th)
252 {
253         int i = 0;
254
255         for (i = 0; i < 3; i++)
256                 th->temps[i]  = read_reg(th, TEMP_REG[i]);
257 }
258
259 #ifdef DEBUG
260 static void display_stats(struct thermostat *th)
261 {
262         if (th->temps[0] != th->cached_temp[0]
263         ||  th->temps[1] != th->cached_temp[1]
264         ||  th->temps[2] != th->cached_temp[2]) {
265                 printk(KERN_INFO "adt746x: Temperature infos:"
266                                  " thermostats: %d,%d,%d;"
267                                  " limits: %d,%d,%d;"
268                                  " fan speed: %d RPM\n",
269                                  th->temps[0], th->temps[1], th->temps[2],
270                                  th->limits[0],  th->limits[1],  th->limits[2],
271                                  read_fan_speed(th, FAN_SPEED[0]));
272         }
273         th->cached_temp[0] = th->temps[0];
274         th->cached_temp[1] = th->temps[1];
275         th->cached_temp[2] = th->temps[2];
276 }
277 #endif
278
279 static void update_fans_speed (struct thermostat *th)
280 {
281         int lastvar = 0; /* last variation, for iBook */
282         int i = 0;
283
284         /* we don't care about local sensor, so we start at sensor 1 */
285         for (i = 1; i < 3; i++) {
286                 int started = 0;
287                 int fan_number = (therm_type == ADT7460 && i == 2);
288                 int var = th->temps[i] - th->limits[i];
289
290                 if (var > -1) {
291                         int step = (255 - fan_speed) / 7;
292                         int new_speed = 0;
293
294                         /* hysteresis : change fan speed only if variation is
295                          * more than two degrees */
296                         if (abs(var - th->last_var[fan_number]) < 2)
297                                 continue;
298
299                         started = 1;
300                         new_speed = fan_speed + ((var-1)*step);
301
302                         if (new_speed < fan_speed)
303                                 new_speed = fan_speed;
304                         if (new_speed > 255)
305                                 new_speed = 255;
306
307                         if (verbose)
308                                 printk(KERN_DEBUG "adt746x: Setting fans speed to %d "
309                                                  "(limit exceeded by %d on %s) \n",
310                                                 new_speed, var,
311                                                 sensor_location[fan_number+1]);
312                         write_both_fan_speed(th, new_speed);
313                         th->last_var[fan_number] = var;
314                 } else if (var < -2) {
315                         /* don't stop fan if sensor2 is cold and sensor1 is not
316                          * so cold (lastvar >= -1) */
317                         if (i == 2 && lastvar < -1) {
318                                 if (th->last_speed[fan_number] != 0)
319                                         if (verbose)
320                                                 printk(KERN_DEBUG "adt746x: Stopping "
321                                                         "fans.\n");
322                                 write_both_fan_speed(th, 0);
323                         }
324                 }
325
326                 lastvar = var;
327
328                 if (started)
329                         return; /* we don't want to re-stop the fan
330                                 * if sensor1 is heating and sensor2 is not */
331         }
332 }
333
334 static int monitor_task(void *arg)
335 {
336         struct thermostat* th = arg;
337
338         while(!kthread_should_stop()) {
339                 try_to_freeze();
340                 msleep_interruptible(2000);
341
342 #ifndef DEBUG
343                 if (fan_speed != -1)
344                         read_sensors(th);
345 #else
346                 read_sensors(th);
347 #endif          
348
349                 if (fan_speed != -1)
350                         update_fans_speed(th);
351
352 #ifdef DEBUG
353                 display_stats(th);
354 #endif
355
356         }
357
358         return 0;
359 }
360
361 static void set_limit(struct thermostat *th, int i)
362 {
363                 /* Set sensor1 limit higher to avoid powerdowns */
364                 th->limits[i] = default_limits_chip[i] + limit_adjust;
365                 write_reg(th, LIMIT_REG[i], th->limits[i]);
366                 
367                 /* set our limits to normal */
368                 th->limits[i] = default_limits_local[i] + limit_adjust;
369 }
370
371 static int attach_one_thermostat(struct i2c_adapter *adapter, int addr,
372                                  int busno)
373 {
374         struct thermostat* th;
375         int rc;
376         int i;
377
378         if (thermostat)
379                 return 0;
380
381         th = (struct thermostat *)
382                 kmalloc(sizeof(struct thermostat), GFP_KERNEL);
383
384         if (!th)
385                 return -ENOMEM;
386
387         memset(th, 0, sizeof(*th));
388         th->clt.addr = addr;
389         th->clt.adapter = adapter;
390         th->clt.driver = &thermostat_driver;
391         strcpy(th->clt.name, "thermostat");
392
393         rc = read_reg(th, 0);
394         if (rc < 0) {
395                 printk(KERN_ERR "adt746x: Thermostat failed to read config "
396                                 "from bus %d !\n",
397                                 busno);
398                 kfree(th);
399                 return -ENODEV;
400         }
401
402         /* force manual control to start the fan quieter */
403         if (fan_speed == -1)
404                 fan_speed = 64;
405         
406         if(therm_type == ADT7460) {
407                 printk(KERN_INFO "adt746x: ADT7460 initializing\n");
408                 /* The 7460 needs to be started explicitly */
409                 write_reg(th, CONFIG_REG, 1);
410         } else
411                 printk(KERN_INFO "adt746x: ADT7467 initializing\n");
412
413         for (i = 0; i < 3; i++) {
414                 th->initial_limits[i] = read_reg(th, LIMIT_REG[i]);
415                 set_limit(th, i);
416         }
417
418         printk(KERN_INFO "adt746x: Lowering max temperatures from %d, %d, %d"
419                          " to %d, %d, %d\n",
420                          th->initial_limits[0], th->initial_limits[1],
421                          th->initial_limits[2], th->limits[0], th->limits[1],
422                          th->limits[2]);
423
424         thermostat = th;
425
426         if (i2c_attach_client(&th->clt)) {
427                 printk(KERN_INFO "adt746x: Thermostat failed to attach "
428                                  "client !\n");
429                 thermostat = NULL;
430                 kfree(th);
431                 return -ENODEV;
432         }
433
434         /* be sure to really write fan speed the first time */
435         th->last_speed[0] = -2;
436         th->last_speed[1] = -2;
437         th->last_var[0] = -80;
438         th->last_var[1] = -80;
439
440         if (fan_speed != -1) {
441                 /* manual mode, stop fans */
442                 write_both_fan_speed(th, 0);
443         } else {
444                 /* automatic mode */
445                 write_both_fan_speed(th, -1);
446         }
447         
448         thread_therm = kthread_run(monitor_task, th, "kfand");
449
450         if (thread_therm == ERR_PTR(-ENOMEM)) {
451                 printk(KERN_INFO "adt746x: Kthread creation failed\n");
452                 thread_therm = NULL;
453                 return -ENOMEM;
454         }
455
456         return 0;
457 }
458
459 /* 
460  * Now, unfortunately, sysfs doesn't give us a nice void * we could
461  * pass around to the attribute functions, so we don't really have
462  * choice but implement a bunch of them...
463  *
464  * FIXME, it does now...
465  */
466 #define BUILD_SHOW_FUNC_INT(name, data)                         \
467 static ssize_t show_##name(struct device *dev, struct device_attribute *attr, char *buf)        \
468 {                                                               \
469         return sprintf(buf, "%d\n", data);                      \
470 }
471
472 #define BUILD_SHOW_FUNC_STR(name, data)                         \
473 static ssize_t show_##name(struct device *dev, struct device_attribute *attr, char *buf)       \
474 {                                                               \
475         return sprintf(buf, "%s\n", data);                      \
476 }
477
478 #define BUILD_SHOW_FUNC_FAN(name, data)                         \
479 static ssize_t show_##name(struct device *dev, struct device_attribute *attr, char *buf)       \
480 {                                                               \
481         return sprintf(buf, "%d (%d rpm)\n",                    \
482                 thermostat->last_speed[data],                   \
483                 read_fan_speed(thermostat, FAN_SPEED[data])     \
484                 );                                              \
485 }
486
487 #define BUILD_STORE_FUNC_DEG(name, data)                        \
488 static ssize_t store_##name(struct device *dev, struct device_attribute *attr, const char *buf, size_t n) \
489 {                                                               \
490         int val;                                                \
491         int i;                                                  \
492         val = simple_strtol(buf, NULL, 10);                     \
493         printk(KERN_INFO "Adjusting limits by %d degrees\n", val);      \
494         limit_adjust = val;                                     \
495         for (i=0; i < 3; i++)                                   \
496                 set_limit(thermostat, i);                       \
497         return n;                                               \
498 }
499
500 #define BUILD_STORE_FUNC_INT(name, data)                        \
501 static ssize_t store_##name(struct device *dev, struct device_attribute *attr, const char *buf, size_t n) \
502 {                                                               \
503         u32 val;                                                \
504         val = simple_strtoul(buf, NULL, 10);                    \
505         if (val < 0 || val > 255)                               \
506                 return -EINVAL;                                 \
507         printk(KERN_INFO "Setting specified fan speed to %d\n", val);   \
508         data = val;                                             \
509         return n;                                               \
510 }
511
512 BUILD_SHOW_FUNC_INT(sensor1_temperature,         (read_reg(thermostat, TEMP_REG[1])))
513 BUILD_SHOW_FUNC_INT(sensor2_temperature,         (read_reg(thermostat, TEMP_REG[2])))
514 BUILD_SHOW_FUNC_INT(sensor1_limit,               thermostat->limits[1])
515 BUILD_SHOW_FUNC_INT(sensor2_limit,               thermostat->limits[2])
516 BUILD_SHOW_FUNC_STR(sensor1_location,            sensor_location[1])
517 BUILD_SHOW_FUNC_STR(sensor2_location,            sensor_location[2])
518
519 BUILD_SHOW_FUNC_INT(specified_fan_speed, fan_speed)
520 BUILD_SHOW_FUNC_FAN(sensor1_fan_speed,   0)
521 BUILD_SHOW_FUNC_FAN(sensor2_fan_speed,   1)
522
523 BUILD_STORE_FUNC_INT(specified_fan_speed,fan_speed)
524 BUILD_SHOW_FUNC_INT(limit_adjust,        limit_adjust)
525 BUILD_STORE_FUNC_DEG(limit_adjust,       thermostat)
526                 
527 static DEVICE_ATTR(sensor1_temperature, S_IRUGO,
528                    show_sensor1_temperature,NULL);
529 static DEVICE_ATTR(sensor2_temperature, S_IRUGO,
530                    show_sensor2_temperature,NULL);
531 static DEVICE_ATTR(sensor1_limit, S_IRUGO,
532                    show_sensor1_limit,  NULL);
533 static DEVICE_ATTR(sensor2_limit, S_IRUGO,
534                    show_sensor2_limit,  NULL);
535 static DEVICE_ATTR(sensor1_location, S_IRUGO,
536                    show_sensor1_location, NULL);
537 static DEVICE_ATTR(sensor2_location, S_IRUGO,
538                    show_sensor2_location, NULL);
539
540 static DEVICE_ATTR(specified_fan_speed, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH,
541                    show_specified_fan_speed,store_specified_fan_speed);
542
543 static DEVICE_ATTR(sensor1_fan_speed,   S_IRUGO,
544                    show_sensor1_fan_speed,      NULL);
545 static DEVICE_ATTR(sensor2_fan_speed,   S_IRUGO,
546                    show_sensor2_fan_speed,      NULL);
547
548 static DEVICE_ATTR(limit_adjust,        S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH,
549                    show_limit_adjust,   store_limit_adjust);
550
551
552 static int __init
553 thermostat_init(void)
554 {
555         struct device_node* np;
556         const u32 *prop;
557         int i = 0, offset = 0;
558         
559         np = of_find_node_by_name(NULL, "fan");
560         if (!np)
561                 return -ENODEV;
562         if (device_is_compatible(np, "adt7460"))
563                 therm_type = ADT7460;
564         else if (device_is_compatible(np, "adt7467"))
565                 therm_type = ADT7467;
566         else
567                 return -ENODEV;
568
569         prop = of_get_property(np, "hwsensor-params-version", NULL);
570         printk(KERN_INFO "adt746x: version %d (%ssupported)\n", *prop,
571                          (*prop == 1)?"":"un");
572         if (*prop != 1)
573                 return -ENODEV;
574
575         prop = of_get_property(np, "reg", NULL);
576         if (!prop)
577                 return -ENODEV;
578
579         /* look for bus either by path or using "reg" */
580         if (strstr(np->full_name, "/i2c-bus@") != NULL) {
581                 const char *tmp_bus = (strstr(np->full_name, "/i2c-bus@") + 9);
582                 therm_bus = tmp_bus[0]-'0';
583         } else {
584                 therm_bus = ((*prop) >> 8) & 0x0f;
585         }
586
587         therm_address = ((*prop) & 0xff) >> 1;
588
589         printk(KERN_INFO "adt746x: Thermostat bus: %d, address: 0x%02x, "
590                          "limit_adjust: %d, fan_speed: %d\n",
591                          therm_bus, therm_address, limit_adjust, fan_speed);
592
593         if (of_get_property(np, "hwsensor-location", NULL)) {
594                 for (i = 0; i < 3; i++) {
595                         sensor_location[i] = of_get_property(np,
596                                         "hwsensor-location", NULL) + offset;
597
598                         if (sensor_location[i] == NULL)
599                                 sensor_location[i] = "";
600
601                         printk(KERN_INFO "sensor %d: %s\n", i, sensor_location[i]);
602                         offset += strlen(sensor_location[i]) + 1;
603                 }
604         } else {
605                 sensor_location[0] = "?";
606                 sensor_location[1] = "?";
607                 sensor_location[2] = "?";
608         }
609
610         of_dev = of_platform_device_create(np, "temperatures", NULL);
611         
612         if (of_dev == NULL) {
613                 printk(KERN_ERR "Can't register temperatures device !\n");
614                 return -ENODEV;
615         }
616         
617         device_create_file(&of_dev->dev, &dev_attr_sensor1_temperature);
618         device_create_file(&of_dev->dev, &dev_attr_sensor2_temperature);
619         device_create_file(&of_dev->dev, &dev_attr_sensor1_limit);
620         device_create_file(&of_dev->dev, &dev_attr_sensor2_limit);
621         device_create_file(&of_dev->dev, &dev_attr_sensor1_location);
622         device_create_file(&of_dev->dev, &dev_attr_sensor2_location);
623         device_create_file(&of_dev->dev, &dev_attr_limit_adjust);
624         device_create_file(&of_dev->dev, &dev_attr_specified_fan_speed);
625         device_create_file(&of_dev->dev, &dev_attr_sensor1_fan_speed);
626         if(therm_type == ADT7460)
627                 device_create_file(&of_dev->dev, &dev_attr_sensor2_fan_speed);
628
629 #ifndef CONFIG_I2C_POWERMAC
630         request_module("i2c-powermac");
631 #endif
632
633         return i2c_add_driver(&thermostat_driver);
634 }
635
636 static void __exit
637 thermostat_exit(void)
638 {
639         if (of_dev) {
640                 device_remove_file(&of_dev->dev, &dev_attr_sensor1_temperature);
641                 device_remove_file(&of_dev->dev, &dev_attr_sensor2_temperature);
642                 device_remove_file(&of_dev->dev, &dev_attr_sensor1_limit);
643                 device_remove_file(&of_dev->dev, &dev_attr_sensor2_limit);
644                 device_remove_file(&of_dev->dev, &dev_attr_sensor1_location);
645                 device_remove_file(&of_dev->dev, &dev_attr_sensor2_location);
646                 device_remove_file(&of_dev->dev, &dev_attr_limit_adjust);
647                 device_remove_file(&of_dev->dev, &dev_attr_specified_fan_speed);
648                 device_remove_file(&of_dev->dev, &dev_attr_sensor1_fan_speed);
649
650                 if(therm_type == ADT7460)
651                         device_remove_file(&of_dev->dev,
652                                            &dev_attr_sensor2_fan_speed);
653
654                 of_device_unregister(of_dev);
655         }
656         i2c_del_driver(&thermostat_driver);
657 }
658
659 module_init(thermostat_init);
660 module_exit(thermostat_exit);