1 /*
2  * Windfarm PowerMac thermal control. Core
3  *
4  * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
5  *                    <benh@kernel.crashing.org>
6  *
7  * Released under the term of the GNU GPL v2.
8  *
9  * This core code tracks the list of sensors & controls, register
10  * clients, and holds the kernel thread used for control.
11  *
12  * TODO:
13  *
14  * Add some information about sensor/control type and data format to
15  * sensors/controls, and have the sysfs attribute stuff be moved
16  * generically here instead of hard coded in the platform specific
17  * driver as it us currently
18  *
19  * This however requires solving some annoying lifetime issues with
20  * sysfs which doesn't seem to have lifetime rules for struct attribute,
21  * I may have to create full features kobjects for every sensor/control
22  * instead which is a bit of an overkill imho
23  */
24 
25 #include <linux/types.h>
26 #include <linux/errno.h>
27 #include <linux/kernel.h>
28 #include <linux/slab.h>
29 #include <linux/init.h>
30 #include <linux/spinlock.h>
31 #include <linux/kthread.h>
32 #include <linux/jiffies.h>
33 #include <linux/reboot.h>
34 #include <linux/device.h>
35 #include <linux/platform_device.h>
36 #include <linux/mutex.h>
37 #include <linux/freezer.h>
38 
39 #include <asm/prom.h>
40 
41 #include "windfarm.h"
42 
43 #define VERSION "0.2"
44 
45 #undef DEBUG
46 
47 #ifdef DEBUG
48 #define DBG(args...)	printk(args)
49 #else
50 #define DBG(args...)	do { } while(0)
51 #endif
52 
53 static LIST_HEAD(wf_controls);
54 static LIST_HEAD(wf_sensors);
55 static DEFINE_MUTEX(wf_lock);
56 static BLOCKING_NOTIFIER_HEAD(wf_client_list);
57 static int wf_client_count;
58 static unsigned int wf_overtemp;
59 static unsigned int wf_overtemp_counter;
60 struct task_struct *wf_thread;
61 
62 static struct platform_device wf_platform_device = {
63 	.name	= "windfarm",
64 };
65 
66 /*
67  * Utilities & tick thread
68  */
69 
70 static inline void wf_notify(int event, void *param)
71 {
72 	blocking_notifier_call_chain(&wf_client_list, event, param);
73 }
74 
75 int wf_critical_overtemp(void)
76 {
77 	static char * critical_overtemp_path = "/sbin/critical_overtemp";
78 	char *argv[] = { critical_overtemp_path, NULL };
79 	static char *envp[] = { "HOME=/",
80 				"TERM=linux",
81 				"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
82 				NULL };
83 
84 	return call_usermodehelper(critical_overtemp_path,
85 				   argv, envp, UMH_WAIT_EXEC);
86 }
87 EXPORT_SYMBOL_GPL(wf_critical_overtemp);
88 
89 static int wf_thread_func(void *data)
90 {
91 	unsigned long next, delay;
92 
93 	next = jiffies;
94 
95 	DBG("wf: thread started\n");
96 
97 	set_freezable();
98 	while (!kthread_should_stop()) {
99 		try_to_freeze();
100 
101 		if (time_after_eq(jiffies, next)) {
102 			wf_notify(WF_EVENT_TICK, NULL);
103 			if (wf_overtemp) {
104 				wf_overtemp_counter++;
105 				/* 10 seconds overtemp, notify userland */
106 				if (wf_overtemp_counter > 10)
107 					wf_critical_overtemp();
108 				/* 30 seconds, shutdown */
109 				if (wf_overtemp_counter > 30) {
110 					printk(KERN_ERR "windfarm: Overtemp "
111 					       "for more than 30"
112 					       " seconds, shutting down\n");
113 					machine_power_off();
114 				}
115 			}
116 			next += HZ;
117 		}
118 
119 		delay = next - jiffies;
120 		if (delay <= HZ)
121 			schedule_timeout_interruptible(delay);
122 	}
123 
124 	DBG("wf: thread stopped\n");
125 
126 	return 0;
127 }
128 
129 static void wf_start_thread(void)
130 {
131 	wf_thread = kthread_run(wf_thread_func, NULL, "kwindfarm");
132 	if (IS_ERR(wf_thread)) {
133 		printk(KERN_ERR "windfarm: failed to create thread,err %ld\n",
134 		       PTR_ERR(wf_thread));
135 		wf_thread = NULL;
136 	}
137 }
138 
139 
140 static void wf_stop_thread(void)
141 {
142 	if (wf_thread)
143 		kthread_stop(wf_thread);
144 	wf_thread = NULL;
145 }
146 
147 /*
148  * Controls
149  */
150 
151 static void wf_control_release(struct kref *kref)
152 {
153 	struct wf_control *ct = container_of(kref, struct wf_control, ref);
154 
155 	DBG("wf: Deleting control %s\n", ct->name);
156 
157 	if (ct->ops && ct->ops->release)
158 		ct->ops->release(ct);
159 	else
160 		kfree(ct);
161 }
162 
163 static ssize_t wf_show_control(struct device *dev,
164 			       struct device_attribute *attr, char *buf)
165 {
166 	struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
167 	const char *typestr;
168 	s32 val = 0;
169 	int err;
170 
171 	err = ctrl->ops->get_value(ctrl, &val);
172 	if (err < 0) {
173 		if (err == -EFAULT)
174 			return sprintf(buf, "<HW FAULT>\n");
175 		return err;
176 	}
177 	switch(ctrl->type) {
178 	case WF_CONTROL_RPM_FAN:
179 		typestr = " RPM";
180 		break;
181 	case WF_CONTROL_PWM_FAN:
182 		typestr = " %";
183 		break;
184 	default:
185 		typestr = "";
186 	}
187 	return sprintf(buf, "%d%s\n", val, typestr);
188 }
189 
190 /* This is really only for debugging... */
191 static ssize_t wf_store_control(struct device *dev,
192 				struct device_attribute *attr,
193 				const char *buf, size_t count)
194 {
195 	struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
196 	int val;
197 	int err;
198 	char *endp;
199 
200 	val = simple_strtoul(buf, &endp, 0);
201 	while (endp < buf + count && (*endp == ' ' || *endp == '\n'))
202 		++endp;
203 	if (endp - buf < count)
204 		return -EINVAL;
205 	err = ctrl->ops->set_value(ctrl, val);
206 	if (err < 0)
207 		return err;
208 	return count;
209 }
210 
211 int wf_register_control(struct wf_control *new_ct)
212 {
213 	struct wf_control *ct;
214 
215 	mutex_lock(&wf_lock);
216 	list_for_each_entry(ct, &wf_controls, link) {
217 		if (!strcmp(ct->name, new_ct->name)) {
218 			printk(KERN_WARNING "windfarm: trying to register"
219 			       " duplicate control %s\n", ct->name);
220 			mutex_unlock(&wf_lock);
221 			return -EEXIST;
222 		}
223 	}
224 	kref_init(&new_ct->ref);
225 	list_add(&new_ct->link, &wf_controls);
226 
227 	sysfs_attr_init(&new_ct->attr.attr);
228 	new_ct->attr.attr.name = new_ct->name;
229 	new_ct->attr.attr.mode = 0644;
230 	new_ct->attr.show = wf_show_control;
231 	new_ct->attr.store = wf_store_control;
232 	if (device_create_file(&wf_platform_device.dev, &new_ct->attr))
233 		printk(KERN_WARNING "windfarm: device_create_file failed"
234 			" for %s\n", new_ct->name);
235 		/* the subsystem still does useful work without the file */
236 
237 	DBG("wf: Registered control %s\n", new_ct->name);
238 
239 	wf_notify(WF_EVENT_NEW_CONTROL, new_ct);
240 	mutex_unlock(&wf_lock);
241 
242 	return 0;
243 }
244 EXPORT_SYMBOL_GPL(wf_register_control);
245 
246 void wf_unregister_control(struct wf_control *ct)
247 {
248 	mutex_lock(&wf_lock);
249 	list_del(&ct->link);
250 	mutex_unlock(&wf_lock);
251 
252 	DBG("wf: Unregistered control %s\n", ct->name);
253 
254 	kref_put(&ct->ref, wf_control_release);
255 }
256 EXPORT_SYMBOL_GPL(wf_unregister_control);
257 
258 struct wf_control * wf_find_control(const char *name)
259 {
260 	struct wf_control *ct;
261 
262 	mutex_lock(&wf_lock);
263 	list_for_each_entry(ct, &wf_controls, link) {
264 		if (!strcmp(ct->name, name)) {
265 			if (wf_get_control(ct))
266 				ct = NULL;
267 			mutex_unlock(&wf_lock);
268 			return ct;
269 		}
270 	}
271 	mutex_unlock(&wf_lock);
272 	return NULL;
273 }
274 EXPORT_SYMBOL_GPL(wf_find_control);
275 
276 int wf_get_control(struct wf_control *ct)
277 {
278 	if (!try_module_get(ct->ops->owner))
279 		return -ENODEV;
280 	kref_get(&ct->ref);
281 	return 0;
282 }
283 EXPORT_SYMBOL_GPL(wf_get_control);
284 
285 void wf_put_control(struct wf_control *ct)
286 {
287 	struct module *mod = ct->ops->owner;
288 	kref_put(&ct->ref, wf_control_release);
289 	module_put(mod);
290 }
291 EXPORT_SYMBOL_GPL(wf_put_control);
292 
293 
294 /*
295  * Sensors
296  */
297 
298 
299 static void wf_sensor_release(struct kref *kref)
300 {
301 	struct wf_sensor *sr = container_of(kref, struct wf_sensor, ref);
302 
303 	DBG("wf: Deleting sensor %s\n", sr->name);
304 
305 	if (sr->ops && sr->ops->release)
306 		sr->ops->release(sr);
307 	else
308 		kfree(sr);
309 }
310 
311 static ssize_t wf_show_sensor(struct device *dev,
312 			      struct device_attribute *attr, char *buf)
313 {
314 	struct wf_sensor *sens = container_of(attr, struct wf_sensor, attr);
315 	s32 val = 0;
316 	int err;
317 
318 	err = sens->ops->get_value(sens, &val);
319 	if (err < 0)
320 		return err;
321 	return sprintf(buf, "%d.%03d\n", FIX32TOPRINT(val));
322 }
323 
324 int wf_register_sensor(struct wf_sensor *new_sr)
325 {
326 	struct wf_sensor *sr;
327 
328 	mutex_lock(&wf_lock);
329 	list_for_each_entry(sr, &wf_sensors, link) {
330 		if (!strcmp(sr->name, new_sr->name)) {
331 			printk(KERN_WARNING "windfarm: trying to register"
332 			       " duplicate sensor %s\n", sr->name);
333 			mutex_unlock(&wf_lock);
334 			return -EEXIST;
335 		}
336 	}
337 	kref_init(&new_sr->ref);
338 	list_add(&new_sr->link, &wf_sensors);
339 
340 	sysfs_attr_init(&new_sr->attr.attr);
341 	new_sr->attr.attr.name = new_sr->name;
342 	new_sr->attr.attr.mode = 0444;
343 	new_sr->attr.show = wf_show_sensor;
344 	new_sr->attr.store = NULL;
345 	if (device_create_file(&wf_platform_device.dev, &new_sr->attr))
346 		printk(KERN_WARNING "windfarm: device_create_file failed"
347 			" for %s\n", new_sr->name);
348 		/* the subsystem still does useful work without the file */
349 
350 	DBG("wf: Registered sensor %s\n", new_sr->name);
351 
352 	wf_notify(WF_EVENT_NEW_SENSOR, new_sr);
353 	mutex_unlock(&wf_lock);
354 
355 	return 0;
356 }
357 EXPORT_SYMBOL_GPL(wf_register_sensor);
358 
359 void wf_unregister_sensor(struct wf_sensor *sr)
360 {
361 	mutex_lock(&wf_lock);
362 	list_del(&sr->link);
363 	mutex_unlock(&wf_lock);
364 
365 	DBG("wf: Unregistered sensor %s\n", sr->name);
366 
367 	wf_put_sensor(sr);
368 }
369 EXPORT_SYMBOL_GPL(wf_unregister_sensor);
370 
371 struct wf_sensor * wf_find_sensor(const char *name)
372 {
373 	struct wf_sensor *sr;
374 
375 	mutex_lock(&wf_lock);
376 	list_for_each_entry(sr, &wf_sensors, link) {
377 		if (!strcmp(sr->name, name)) {
378 			if (wf_get_sensor(sr))
379 				sr = NULL;
380 			mutex_unlock(&wf_lock);
381 			return sr;
382 		}
383 	}
384 	mutex_unlock(&wf_lock);
385 	return NULL;
386 }
387 EXPORT_SYMBOL_GPL(wf_find_sensor);
388 
389 int wf_get_sensor(struct wf_sensor *sr)
390 {
391 	if (!try_module_get(sr->ops->owner))
392 		return -ENODEV;
393 	kref_get(&sr->ref);
394 	return 0;
395 }
396 EXPORT_SYMBOL_GPL(wf_get_sensor);
397 
398 void wf_put_sensor(struct wf_sensor *sr)
399 {
400 	struct module *mod = sr->ops->owner;
401 	kref_put(&sr->ref, wf_sensor_release);
402 	module_put(mod);
403 }
404 EXPORT_SYMBOL_GPL(wf_put_sensor);
405 
406 
407 /*
408  * Client & notification
409  */
410 
411 int wf_register_client(struct notifier_block *nb)
412 {
413 	int rc;
414 	struct wf_control *ct;
415 	struct wf_sensor *sr;
416 
417 	mutex_lock(&wf_lock);
418 	rc = blocking_notifier_chain_register(&wf_client_list, nb);
419 	if (rc != 0)
420 		goto bail;
421 	wf_client_count++;
422 	list_for_each_entry(ct, &wf_controls, link)
423 		wf_notify(WF_EVENT_NEW_CONTROL, ct);
424 	list_for_each_entry(sr, &wf_sensors, link)
425 		wf_notify(WF_EVENT_NEW_SENSOR, sr);
426 	if (wf_client_count == 1)
427 		wf_start_thread();
428  bail:
429 	mutex_unlock(&wf_lock);
430 	return rc;
431 }
432 EXPORT_SYMBOL_GPL(wf_register_client);
433 
434 int wf_unregister_client(struct notifier_block *nb)
435 {
436 	mutex_lock(&wf_lock);
437 	blocking_notifier_chain_unregister(&wf_client_list, nb);
438 	wf_client_count++;
439 	if (wf_client_count == 0)
440 		wf_stop_thread();
441 	mutex_unlock(&wf_lock);
442 
443 	return 0;
444 }
445 EXPORT_SYMBOL_GPL(wf_unregister_client);
446 
447 void wf_set_overtemp(void)
448 {
449 	mutex_lock(&wf_lock);
450 	wf_overtemp++;
451 	if (wf_overtemp == 1) {
452 		printk(KERN_WARNING "windfarm: Overtemp condition detected !\n");
453 		wf_overtemp_counter = 0;
454 		wf_notify(WF_EVENT_OVERTEMP, NULL);
455 	}
456 	mutex_unlock(&wf_lock);
457 }
458 EXPORT_SYMBOL_GPL(wf_set_overtemp);
459 
460 void wf_clear_overtemp(void)
461 {
462 	mutex_lock(&wf_lock);
463 	WARN_ON(wf_overtemp == 0);
464 	if (wf_overtemp == 0) {
465 		mutex_unlock(&wf_lock);
466 		return;
467 	}
468 	wf_overtemp--;
469 	if (wf_overtemp == 0) {
470 		printk(KERN_WARNING "windfarm: Overtemp condition cleared !\n");
471 		wf_notify(WF_EVENT_NORMALTEMP, NULL);
472 	}
473 	mutex_unlock(&wf_lock);
474 }
475 EXPORT_SYMBOL_GPL(wf_clear_overtemp);
476 
477 int wf_is_overtemp(void)
478 {
479 	return (wf_overtemp != 0);
480 }
481 EXPORT_SYMBOL_GPL(wf_is_overtemp);
482 
483 static int __init windfarm_core_init(void)
484 {
485 	DBG("wf: core loaded\n");
486 
487 	platform_device_register(&wf_platform_device);
488 	return 0;
489 }
490 
491 static void __exit windfarm_core_exit(void)
492 {
493 	BUG_ON(wf_client_count != 0);
494 
495 	DBG("wf: core unloaded\n");
496 
497 	platform_device_unregister(&wf_platform_device);
498 }
499 
500 
501 module_init(windfarm_core_init);
502 module_exit(windfarm_core_exit);
503 
504 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
505 MODULE_DESCRIPTION("Core component of PowerMac thermal control");
506 MODULE_LICENSE("GPL");
507 
508