1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Device driver for the i2c thermostat found on the iBook G4, Albook G4
4  *
5  * Copyright (C) 2003, 2004 Colin Leroy, Rasmus Rohde, Benjamin Herrenschmidt
6  *
7  * Documentation from 115254175ADT7467_pra.pdf and 3686221171167ADT7460_b.pdf
8  * https://www.onsemi.com/PowerSolutions/product.do?id=ADT7467
9  * https://www.onsemi.com/PowerSolutions/product.do?id=ADT7460
10  *
11  */
12 
13 #include <linux/types.h>
14 #include <linux/module.h>
15 #include <linux/errno.h>
16 #include <linux/kernel.h>
17 #include <linux/delay.h>
18 #include <linux/sched.h>
19 #include <linux/i2c.h>
20 #include <linux/slab.h>
21 #include <linux/init.h>
22 #include <linux/spinlock.h>
23 #include <linux/wait.h>
24 #include <linux/suspend.h>
25 #include <linux/kthread.h>
26 #include <linux/moduleparam.h>
27 #include <linux/freezer.h>
28 #include <linux/of.h>
29 #include <linux/of_platform.h>
30 #include <linux/platform_device.h>
31 
32 #include <asm/machdep.h>
33 #include <asm/io.h>
34 #include <asm/sections.h>
35 
36 #undef DEBUG
37 
38 #define CONFIG_REG   0x40
39 #define MANUAL_MASK  0xe0
40 #define AUTO_MASK    0x20
41 #define INVERT_MASK  0x10
42 
43 static u8 TEMP_REG[3]    = {0x26, 0x25, 0x27}; /* local, sensor1, sensor2 */
44 static u8 LIMIT_REG[3]   = {0x6b, 0x6a, 0x6c}; /* local, sensor1, sensor2 */
45 static u8 MANUAL_MODE[2] = {0x5c, 0x5d};
46 static u8 REM_CONTROL[2] = {0x00, 0x40};
47 static u8 FAN_SPEED[2]   = {0x28, 0x2a};
48 static u8 FAN_SPD_SET[2] = {0x30, 0x31};
49 
50 static u8 default_limits_local[3] = {70, 50, 70};    /* local, sensor1, sensor2 */
51 static u8 default_limits_chip[3] = {80, 65, 80};    /* local, sensor1, sensor2 */
52 static const char *sensor_location[3] = { "?", "?", "?" };
53 
54 static int limit_adjust;
55 static int fan_speed = -1;
56 static bool verbose;
57 
58 MODULE_AUTHOR("Colin Leroy <colin@colino.net>");
59 MODULE_DESCRIPTION("Driver for ADT746x thermostat in iBook G4 and "
60 		   "Powerbook G4 Alu");
61 MODULE_LICENSE("GPL");
62 
63 module_param(limit_adjust, int, 0644);
64 MODULE_PARM_DESC(limit_adjust,"Adjust maximum temperatures (50 sensor1, 70 sensor2) "
65 		 "by N degrees.");
66 
67 module_param(fan_speed, int, 0644);
68 MODULE_PARM_DESC(fan_speed,"Specify starting fan speed (0-255) "
69 		 "(default 64)");
70 
71 module_param(verbose, bool, 0);
72 MODULE_PARM_DESC(verbose,"Verbose log operations "
73 		 "(default 0)");
74 
75 struct thermostat {
76 	struct i2c_client	*clt;
77 	u8			temps[3];
78 	u8			cached_temp[3];
79 	u8			initial_limits[3];
80 	u8			limits[3];
81 	int			last_speed[2];
82 	int			last_var[2];
83 	int			pwm_inv[2];
84 	struct task_struct	*thread;
85 	struct platform_device	*pdev;
86 	enum {
87 		ADT7460,
88 		ADT7467
89 	}			type;
90 };
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
write_reg(struct thermostat * th,int reg,u8 data)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
read_reg(struct thermostat * th,int reg)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 
read_fan_speed(struct thermostat * th,u8 addr)129 static int read_fan_speed(struct thermostat *th, u8 addr)
130 {
131 	u8 tmp[2];
132 	u16 res;
133 
134 	/* should start with low byte */
135 	tmp[1] = read_reg(th, addr);
136 	tmp[0] = read_reg(th, addr + 1);
137 
138 	res = tmp[1] + (tmp[0] << 8);
139 	/* "a value of 0xffff means that the fan has stopped" */
140 	return (res == 0xffff ? 0 : (90000*60)/res);
141 }
142 
write_both_fan_speed(struct thermostat * th,int speed)143 static void write_both_fan_speed(struct thermostat *th, int speed)
144 {
145 	write_fan_speed(th, speed, 0);
146 	if (th->type == ADT7460)
147 		write_fan_speed(th, speed, 1);
148 }
149 
write_fan_speed(struct thermostat * th,int speed,int fan)150 static void write_fan_speed(struct thermostat *th, int speed, int fan)
151 {
152 	u8 manual;
153 
154 	if (speed > 0xff)
155 		speed = 0xff;
156 	else if (speed < -1)
157 		speed = 0;
158 
159 	if (th->type == ADT7467 && fan == 1)
160 		return;
161 
162 	if (th->last_speed[fan] != speed) {
163 		if (verbose) {
164 			if (speed == -1)
165 				printk(KERN_DEBUG "adt746x: Setting speed to automatic "
166 					"for %s fan.\n", sensor_location[fan+1]);
167 			else
168 				printk(KERN_DEBUG "adt746x: Setting speed to %d "
169 					"for %s fan.\n", speed, sensor_location[fan+1]);
170 		}
171 	} else
172 		return;
173 
174 	if (speed >= 0) {
175 		manual = read_reg(th, MANUAL_MODE[fan]);
176 		manual &= ~INVERT_MASK;
177 		write_reg(th, MANUAL_MODE[fan],
178 			manual | MANUAL_MASK | th->pwm_inv[fan]);
179 		write_reg(th, FAN_SPD_SET[fan], speed);
180 	} else {
181 		/* back to automatic */
182 		if(th->type == ADT7460) {
183 			manual = read_reg(th,
184 				MANUAL_MODE[fan]) & (~MANUAL_MASK);
185 			manual &= ~INVERT_MASK;
186 			manual |= th->pwm_inv[fan];
187 			write_reg(th,
188 				MANUAL_MODE[fan], manual|REM_CONTROL[fan]);
189 		} else {
190 			manual = read_reg(th, MANUAL_MODE[fan]);
191 			manual &= ~INVERT_MASK;
192 			manual |= th->pwm_inv[fan];
193 			write_reg(th, MANUAL_MODE[fan], manual&(~AUTO_MASK));
194 		}
195 	}
196 
197 	th->last_speed[fan] = speed;
198 }
199 
read_sensors(struct thermostat * th)200 static void read_sensors(struct thermostat *th)
201 {
202 	int i = 0;
203 
204 	for (i = 0; i < 3; i++)
205 		th->temps[i]  = read_reg(th, TEMP_REG[i]);
206 }
207 
208 #ifdef DEBUG
display_stats(struct thermostat * th)209 static void display_stats(struct thermostat *th)
210 {
211 	if (th->temps[0] != th->cached_temp[0]
212 	||  th->temps[1] != th->cached_temp[1]
213 	||  th->temps[2] != th->cached_temp[2]) {
214 		printk(KERN_INFO "adt746x: Temperature infos:"
215 				 " thermostats: %d,%d,%d;"
216 				 " limits: %d,%d,%d;"
217 				 " fan speed: %d RPM\n",
218 				 th->temps[0], th->temps[1], th->temps[2],
219 				 th->limits[0],  th->limits[1],  th->limits[2],
220 				 read_fan_speed(th, FAN_SPEED[0]));
221 	}
222 	th->cached_temp[0] = th->temps[0];
223 	th->cached_temp[1] = th->temps[1];
224 	th->cached_temp[2] = th->temps[2];
225 }
226 #endif
227 
update_fans_speed(struct thermostat * th)228 static void update_fans_speed (struct thermostat *th)
229 {
230 	int lastvar = 0; /* last variation, for iBook */
231 	int i = 0;
232 
233 	/* we don't care about local sensor, so we start at sensor 1 */
234 	for (i = 1; i < 3; i++) {
235 		bool started = false;
236 		int fan_number = (th->type == ADT7460 && i == 2);
237 		int var = th->temps[i] - th->limits[i];
238 
239 		if (var > -1) {
240 			int step = (255 - fan_speed) / 7;
241 			int new_speed = 0;
242 
243 			/* hysteresis : change fan speed only if variation is
244 			 * more than two degrees */
245 			if (abs(var - th->last_var[fan_number]) < 2)
246 				continue;
247 
248 			started = true;
249 			new_speed = fan_speed + ((var-1)*step);
250 
251 			if (new_speed < fan_speed)
252 				new_speed = fan_speed;
253 			if (new_speed > 255)
254 				new_speed = 255;
255 
256 			if (verbose)
257 				printk(KERN_DEBUG "adt746x: Setting fans speed to %d "
258 						 "(limit exceeded by %d on %s)\n",
259 						new_speed, var,
260 						sensor_location[fan_number+1]);
261 			write_both_fan_speed(th, new_speed);
262 			th->last_var[fan_number] = var;
263 		} else if (var < -2) {
264 			/* don't stop fan if sensor2 is cold and sensor1 is not
265 			 * so cold (lastvar >= -1) */
266 			if (i == 2 && lastvar < -1) {
267 				if (th->last_speed[fan_number] != 0)
268 					if (verbose)
269 						printk(KERN_DEBUG "adt746x: Stopping "
270 							"fans.\n");
271 				write_both_fan_speed(th, 0);
272 			}
273 		}
274 
275 		lastvar = var;
276 
277 		if (started)
278 			return; /* we don't want to re-stop the fan
279 				* if sensor1 is heating and sensor2 is not */
280 	}
281 }
282 
monitor_task(void * arg)283 static int monitor_task(void *arg)
284 {
285 	struct thermostat* th = arg;
286 
287 	set_freezable();
288 	while(!kthread_should_stop()) {
289 		try_to_freeze();
290 		msleep_interruptible(2000);
291 
292 #ifndef DEBUG
293 		if (fan_speed != -1)
294 			read_sensors(th);
295 #else
296 		read_sensors(th);
297 #endif
298 
299 		if (fan_speed != -1)
300 			update_fans_speed(th);
301 
302 #ifdef DEBUG
303 		display_stats(th);
304 #endif
305 
306 	}
307 
308 	return 0;
309 }
310 
set_limit(struct thermostat * th,int i)311 static void set_limit(struct thermostat *th, int i)
312 {
313 	/* Set sensor1 limit higher to avoid powerdowns */
314 	th->limits[i] = default_limits_chip[i] + limit_adjust;
315 	write_reg(th, LIMIT_REG[i], th->limits[i]);
316 
317 	/* set our limits to normal */
318 	th->limits[i] = default_limits_local[i] + limit_adjust;
319 }
320 
321 #define BUILD_SHOW_FUNC_INT(name, data)				\
322 static ssize_t show_##name(struct device *dev, struct device_attribute *attr, char *buf)	\
323 {								\
324 	struct thermostat *th = dev_get_drvdata(dev);		\
325 	return sprintf(buf, "%d\n", data);			\
326 }
327 
328 #define BUILD_SHOW_FUNC_INT_LITE(name, data)				\
329 static ssize_t show_##name(struct device *dev, struct device_attribute *attr, char *buf)	\
330 {								\
331 	return sprintf(buf, "%d\n", data);			\
332 }
333 
334 #define BUILD_SHOW_FUNC_STR(name, data)				\
335 static ssize_t show_##name(struct device *dev, struct device_attribute *attr, char *buf)       \
336 {								\
337 	return sprintf(buf, "%s\n", data);			\
338 }
339 
340 #define BUILD_SHOW_FUNC_FAN(name, data)				\
341 static ssize_t show_##name(struct device *dev, struct device_attribute *attr, char *buf)       \
342 {								\
343 	struct thermostat *th = dev_get_drvdata(dev);		\
344 	return sprintf(buf, "%d (%d rpm)\n", 			\
345 		th->last_speed[data],				\
346 		read_fan_speed(th, FAN_SPEED[data])		\
347 		);						\
348 }
349 
350 #define BUILD_STORE_FUNC_DEG(name, data)			\
351 static ssize_t store_##name(struct device *dev, struct device_attribute *attr, const char *buf, size_t n) \
352 {								\
353 	struct thermostat *th = dev_get_drvdata(dev);		\
354 	int val;						\
355 	int i;							\
356 	val = simple_strtol(buf, NULL, 10);			\
357 	printk(KERN_INFO "Adjusting limits by %d degrees\n", val);	\
358 	limit_adjust = val;					\
359 	for (i=0; i < 3; i++)					\
360 		set_limit(th, i);				\
361 	return n;						\
362 }
363 
364 #define BUILD_STORE_FUNC_INT(name, data)			\
365 static ssize_t store_##name(struct device *dev, struct device_attribute *attr, const char *buf, size_t n) \
366 {								\
367 	int val;						\
368 	val = simple_strtol(buf, NULL, 10);			\
369 	if (val < 0 || val > 255)				\
370 		return -EINVAL;					\
371 	printk(KERN_INFO "Setting specified fan speed to %d\n", val);	\
372 	data = val;						\
373 	return n;						\
374 }
375 
376 BUILD_SHOW_FUNC_INT(sensor1_temperature,	 (read_reg(th, TEMP_REG[1])))
377 BUILD_SHOW_FUNC_INT(sensor2_temperature,	 (read_reg(th, TEMP_REG[2])))
378 BUILD_SHOW_FUNC_INT(sensor1_limit,		 th->limits[1])
379 BUILD_SHOW_FUNC_INT(sensor2_limit,		 th->limits[2])
380 BUILD_SHOW_FUNC_STR(sensor1_location,		 sensor_location[1])
381 BUILD_SHOW_FUNC_STR(sensor2_location,		 sensor_location[2])
382 
383 BUILD_SHOW_FUNC_INT_LITE(specified_fan_speed, fan_speed)
384 BUILD_STORE_FUNC_INT(specified_fan_speed,fan_speed)
385 
386 BUILD_SHOW_FUNC_FAN(sensor1_fan_speed,	 0)
387 BUILD_SHOW_FUNC_FAN(sensor2_fan_speed,	 1)
388 
389 BUILD_SHOW_FUNC_INT_LITE(limit_adjust,	 limit_adjust)
390 BUILD_STORE_FUNC_DEG(limit_adjust,	 th)
391 
392 static DEVICE_ATTR(sensor1_temperature,	S_IRUGO,
393 		   show_sensor1_temperature,NULL);
394 static DEVICE_ATTR(sensor2_temperature,	S_IRUGO,
395 		   show_sensor2_temperature,NULL);
396 static DEVICE_ATTR(sensor1_limit, S_IRUGO,
397 		   show_sensor1_limit,	NULL);
398 static DEVICE_ATTR(sensor2_limit, S_IRUGO,
399 		   show_sensor2_limit,	NULL);
400 static DEVICE_ATTR(sensor1_location, S_IRUGO,
401 		   show_sensor1_location, NULL);
402 static DEVICE_ATTR(sensor2_location, S_IRUGO,
403 		   show_sensor2_location, NULL);
404 
405 static DEVICE_ATTR(specified_fan_speed,	S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH,
406 		   show_specified_fan_speed,store_specified_fan_speed);
407 
408 static DEVICE_ATTR(sensor1_fan_speed,	S_IRUGO,
409 		   show_sensor1_fan_speed,	NULL);
410 static DEVICE_ATTR(sensor2_fan_speed,	S_IRUGO,
411 		   show_sensor2_fan_speed,	NULL);
412 
413 static DEVICE_ATTR(limit_adjust,	S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH,
414 		   show_limit_adjust,	store_limit_adjust);
415 
thermostat_create_files(struct thermostat * th)416 static void thermostat_create_files(struct thermostat *th)
417 {
418 	struct device_node *np = th->clt->dev.of_node;
419 	struct device *dev;
420 	int err;
421 
422 	/* To maintain ABI compatibility with userspace, create
423 	 * the old style platform driver and attach the attributes
424 	 * to it here
425 	 */
426 	th->pdev = of_platform_device_create(np, "temperatures", NULL);
427 	if (!th->pdev)
428 		return;
429 	dev = &th->pdev->dev;
430 	dev_set_drvdata(dev, th);
431 	err = device_create_file(dev, &dev_attr_sensor1_temperature);
432 	err |= device_create_file(dev, &dev_attr_sensor2_temperature);
433 	err |= device_create_file(dev, &dev_attr_sensor1_limit);
434 	err |= device_create_file(dev, &dev_attr_sensor2_limit);
435 	err |= device_create_file(dev, &dev_attr_sensor1_location);
436 	err |= device_create_file(dev, &dev_attr_sensor2_location);
437 	err |= device_create_file(dev, &dev_attr_limit_adjust);
438 	err |= device_create_file(dev, &dev_attr_specified_fan_speed);
439 	err |= device_create_file(dev, &dev_attr_sensor1_fan_speed);
440 	if(th->type == ADT7460)
441 		err |= device_create_file(dev, &dev_attr_sensor2_fan_speed);
442 	if (err)
443 		printk(KERN_WARNING
444 			"Failed to create temperature attribute file(s).\n");
445 }
446 
thermostat_remove_files(struct thermostat * th)447 static void thermostat_remove_files(struct thermostat *th)
448 {
449 	struct device *dev;
450 
451 	if (!th->pdev)
452 		return;
453 	dev = &th->pdev->dev;
454 	device_remove_file(dev, &dev_attr_sensor1_temperature);
455 	device_remove_file(dev, &dev_attr_sensor2_temperature);
456 	device_remove_file(dev, &dev_attr_sensor1_limit);
457 	device_remove_file(dev, &dev_attr_sensor2_limit);
458 	device_remove_file(dev, &dev_attr_sensor1_location);
459 	device_remove_file(dev, &dev_attr_sensor2_location);
460 	device_remove_file(dev, &dev_attr_limit_adjust);
461 	device_remove_file(dev, &dev_attr_specified_fan_speed);
462 	device_remove_file(dev, &dev_attr_sensor1_fan_speed);
463 	if (th->type == ADT7460)
464 		device_remove_file(dev, &dev_attr_sensor2_fan_speed);
465 	of_device_unregister(th->pdev);
466 
467 }
468 
probe_thermostat(struct i2c_client * client)469 static int probe_thermostat(struct i2c_client *client)
470 {
471 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
472 	struct device_node *np = client->dev.of_node;
473 	struct thermostat* th;
474 	const __be32 *prop;
475 	int i, rc, vers, offset = 0;
476 
477 	if (!np)
478 		return -ENXIO;
479 	prop = of_get_property(np, "hwsensor-params-version", NULL);
480 	if (!prop)
481 		return -ENXIO;
482 	vers = be32_to_cpup(prop);
483 	printk(KERN_INFO "adt746x: version %d (%ssupported)\n",
484 	       vers, vers == 1 ? "" : "un");
485 	if (vers != 1)
486 		return -ENXIO;
487 
488 	if (of_property_present(np, "hwsensor-location")) {
489 		for (i = 0; i < 3; i++) {
490 			sensor_location[i] = of_get_property(np,
491 					"hwsensor-location", NULL) + offset;
492 
493 			if (sensor_location[i] == NULL)
494 				sensor_location[i] = "";
495 
496 			printk(KERN_INFO "sensor %d: %s\n", i, sensor_location[i]);
497 			offset += strlen(sensor_location[i]) + 1;
498 		}
499 	}
500 
501 	th = kzalloc(sizeof(struct thermostat), GFP_KERNEL);
502 	if (!th)
503 		return -ENOMEM;
504 
505 	i2c_set_clientdata(client, th);
506 	th->clt = client;
507 	th->type = id->driver_data;
508 
509 	rc = read_reg(th, CONFIG_REG);
510 	if (rc < 0) {
511 		dev_err(&client->dev, "Thermostat failed to read config!\n");
512 		kfree(th);
513 		return -ENODEV;
514 	}
515 
516 	/* force manual control to start the fan quieter */
517 	if (fan_speed == -1)
518 		fan_speed = 64;
519 
520 	if (th->type == ADT7460) {
521 		printk(KERN_INFO "adt746x: ADT7460 initializing\n");
522 		/* The 7460 needs to be started explicitly */
523 		write_reg(th, CONFIG_REG, 1);
524 	} else
525 		printk(KERN_INFO "adt746x: ADT7467 initializing\n");
526 
527 	for (i = 0; i < 3; i++) {
528 		th->initial_limits[i] = read_reg(th, LIMIT_REG[i]);
529 		set_limit(th, i);
530 	}
531 
532 	printk(KERN_INFO "adt746x: Lowering max temperatures from %d, %d, %d"
533 			 " to %d, %d, %d\n",
534 			 th->initial_limits[0], th->initial_limits[1],
535 			 th->initial_limits[2], th->limits[0], th->limits[1],
536 			 th->limits[2]);
537 
538 	/* record invert bit status because fw can corrupt it after suspend */
539 	th->pwm_inv[0] = read_reg(th, MANUAL_MODE[0]) & INVERT_MASK;
540 	th->pwm_inv[1] = read_reg(th, MANUAL_MODE[1]) & INVERT_MASK;
541 
542 	/* be sure to really write fan speed the first time */
543 	th->last_speed[0] = -2;
544 	th->last_speed[1] = -2;
545 	th->last_var[0] = -80;
546 	th->last_var[1] = -80;
547 
548 	if (fan_speed != -1) {
549 		/* manual mode, stop fans */
550 		write_both_fan_speed(th, 0);
551 	} else {
552 		/* automatic mode */
553 		write_both_fan_speed(th, -1);
554 	}
555 
556 	th->thread = kthread_run(monitor_task, th, "kfand");
557 	if (th->thread == ERR_PTR(-ENOMEM)) {
558 		printk(KERN_INFO "adt746x: Kthread creation failed\n");
559 		th->thread = NULL;
560 		return -ENOMEM;
561 	}
562 
563 	thermostat_create_files(th);
564 
565 	return 0;
566 }
567 
remove_thermostat(struct i2c_client * client)568 static void remove_thermostat(struct i2c_client *client)
569 {
570 	struct thermostat *th = i2c_get_clientdata(client);
571 	int i;
572 
573 	thermostat_remove_files(th);
574 
575 	if (th->thread != NULL)
576 		kthread_stop(th->thread);
577 
578 	printk(KERN_INFO "adt746x: Putting max temperatures back from "
579 			 "%d, %d, %d to %d, %d, %d\n",
580 		th->limits[0], th->limits[1], th->limits[2],
581 		th->initial_limits[0], th->initial_limits[1],
582 		th->initial_limits[2]);
583 
584 	for (i = 0; i < 3; i++)
585 		write_reg(th, LIMIT_REG[i], th->initial_limits[i]);
586 
587 	write_both_fan_speed(th, -1);
588 
589 	kfree(th);
590 }
591 
592 static const struct i2c_device_id therm_adt746x_id[] = {
593 	{ "MAC,adt7460", ADT7460 },
594 	{ "MAC,adt7467", ADT7467 },
595 	{ }
596 };
597 MODULE_DEVICE_TABLE(i2c, therm_adt746x_id);
598 
599 static struct i2c_driver thermostat_driver = {
600 	.driver = {
601 		.name	= "therm_adt746x",
602 	},
603 	.probe = probe_thermostat,
604 	.remove = remove_thermostat,
605 	.id_table = therm_adt746x_id,
606 };
607 
thermostat_init(void)608 static int __init thermostat_init(void)
609 {
610 #ifndef CONFIG_I2C_POWERMAC
611 	request_module("i2c-powermac");
612 #endif
613 
614 	return i2c_add_driver(&thermostat_driver);
615 }
616 
thermostat_exit(void)617 static void __exit thermostat_exit(void)
618 {
619 	i2c_del_driver(&thermostat_driver);
620 }
621 
622 module_init(thermostat_init);
623 module_exit(thermostat_exit);
624