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/init.h>
29 #include <linux/spinlock.h>
30 #include <linux/kthread.h>
31 #include <linux/jiffies.h>
32 #include <linux/reboot.h>
33 #include <linux/device.h>
34 #include <linux/platform_device.h>
35 #include <linux/mutex.h>
36 #include <linux/freezer.h>
37 
38 #include <asm/prom.h>
39 
40 #include "windfarm.h"
41 
42 #define VERSION "0.2"
43 
44 #undef DEBUG
45 
46 #ifdef DEBUG
47 #define DBG(args...)	printk(args)
48 #else
49 #define DBG(args...)	do { } while(0)
50 #endif
51 
52 static LIST_HEAD(wf_controls);
53 static LIST_HEAD(wf_sensors);
54 static DEFINE_MUTEX(wf_lock);
55 static BLOCKING_NOTIFIER_HEAD(wf_client_list);
56 static int wf_client_count;
57 static unsigned int wf_overtemp;
58 static unsigned int wf_overtemp_counter;
59 struct task_struct *wf_thread;
60 
61 static struct platform_device wf_platform_device = {
62 	.name	= "windfarm",
63 };
64 
65 /*
66  * Utilities & tick thread
67  */
68 
69 static inline void wf_notify(int event, void *param)
70 {
71 	blocking_notifier_call_chain(&wf_client_list, event, param);
72 }
73 
74 int wf_critical_overtemp(void)
75 {
76 	static char * critical_overtemp_path = "/sbin/critical_overtemp";
77 	char *argv[] = { critical_overtemp_path, NULL };
78 	static char *envp[] = { "HOME=/",
79 				"TERM=linux",
80 				"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
81 				NULL };
82 
83 	return call_usermodehelper(critical_overtemp_path,
84 				   argv, envp, UMH_WAIT_EXEC);
85 }
86 EXPORT_SYMBOL_GPL(wf_critical_overtemp);
87 
88 static int wf_thread_func(void *data)
89 {
90 	unsigned long next, delay;
91 
92 	next = jiffies;
93 
94 	DBG("wf: thread started\n");
95 
96 	set_freezable();
97 	while (!kthread_should_stop()) {
98 		try_to_freeze();
99 
100 		if (time_after_eq(jiffies, next)) {
101 			wf_notify(WF_EVENT_TICK, NULL);
102 			if (wf_overtemp) {
103 				wf_overtemp_counter++;
104 				/* 10 seconds overtemp, notify userland */
105 				if (wf_overtemp_counter > 10)
106 					wf_critical_overtemp();
107 				/* 30 seconds, shutdown */
108 				if (wf_overtemp_counter > 30) {
109 					printk(KERN_ERR "windfarm: Overtemp "
110 					       "for more than 30"
111 					       " seconds, shutting down\n");
112 					machine_power_off();
113 				}
114 			}
115 			next += HZ;
116 		}
117 
118 		delay = next - jiffies;
119 		if (delay <= HZ)
120 			schedule_timeout_interruptible(delay);
121 	}
122 
123 	DBG("wf: thread stopped\n");
124 
125 	return 0;
126 }
127 
128 static void wf_start_thread(void)
129 {
130 	wf_thread = kthread_run(wf_thread_func, NULL, "kwindfarm");
131 	if (IS_ERR(wf_thread)) {
132 		printk(KERN_ERR "windfarm: failed to create thread,err %ld\n",
133 		       PTR_ERR(wf_thread));
134 		wf_thread = NULL;
135 	}
136 }
137 
138 
139 static void wf_stop_thread(void)
140 {
141 	if (wf_thread)
142 		kthread_stop(wf_thread);
143 	wf_thread = NULL;
144 }
145 
146 /*
147  * Controls
148  */
149 
150 static void wf_control_release(struct kref *kref)
151 {
152 	struct wf_control *ct = container_of(kref, struct wf_control, ref);
153 
154 	DBG("wf: Deleting control %s\n", ct->name);
155 
156 	if (ct->ops && ct->ops->release)
157 		ct->ops->release(ct);
158 	else
159 		kfree(ct);
160 }
161 
162 static ssize_t wf_show_control(struct device *dev,
163 			       struct device_attribute *attr, char *buf)
164 {
165 	struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
166 	s32 val = 0;
167 	int err;
168 
169 	err = ctrl->ops->get_value(ctrl, &val);
170 	if (err < 0)
171 		return err;
172 	return sprintf(buf, "%d\n", val);
173 }
174 
175 /* This is really only for debugging... */
176 static ssize_t wf_store_control(struct device *dev,
177 				struct device_attribute *attr,
178 				const char *buf, size_t count)
179 {
180 	struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
181 	int val;
182 	int err;
183 	char *endp;
184 
185 	val = simple_strtoul(buf, &endp, 0);
186 	while (endp < buf + count && (*endp == ' ' || *endp == '\n'))
187 		++endp;
188 	if (endp - buf < count)
189 		return -EINVAL;
190 	err = ctrl->ops->set_value(ctrl, val);
191 	if (err < 0)
192 		return err;
193 	return count;
194 }
195 
196 int wf_register_control(struct wf_control *new_ct)
197 {
198 	struct wf_control *ct;
199 
200 	mutex_lock(&wf_lock);
201 	list_for_each_entry(ct, &wf_controls, link) {
202 		if (!strcmp(ct->name, new_ct->name)) {
203 			printk(KERN_WARNING "windfarm: trying to register"
204 			       " duplicate control %s\n", ct->name);
205 			mutex_unlock(&wf_lock);
206 			return -EEXIST;
207 		}
208 	}
209 	kref_init(&new_ct->ref);
210 	list_add(&new_ct->link, &wf_controls);
211 
212 	new_ct->attr.attr.name = new_ct->name;
213 	new_ct->attr.attr.mode = 0644;
214 	new_ct->attr.show = wf_show_control;
215 	new_ct->attr.store = wf_store_control;
216 	if (device_create_file(&wf_platform_device.dev, &new_ct->attr))
217 		printk(KERN_WARNING "windfarm: device_create_file failed"
218 			" for %s\n", new_ct->name);
219 		/* the subsystem still does useful work without the file */
220 
221 	DBG("wf: Registered control %s\n", new_ct->name);
222 
223 	wf_notify(WF_EVENT_NEW_CONTROL, new_ct);
224 	mutex_unlock(&wf_lock);
225 
226 	return 0;
227 }
228 EXPORT_SYMBOL_GPL(wf_register_control);
229 
230 void wf_unregister_control(struct wf_control *ct)
231 {
232 	mutex_lock(&wf_lock);
233 	list_del(&ct->link);
234 	mutex_unlock(&wf_lock);
235 
236 	DBG("wf: Unregistered control %s\n", ct->name);
237 
238 	kref_put(&ct->ref, wf_control_release);
239 }
240 EXPORT_SYMBOL_GPL(wf_unregister_control);
241 
242 struct wf_control * wf_find_control(const char *name)
243 {
244 	struct wf_control *ct;
245 
246 	mutex_lock(&wf_lock);
247 	list_for_each_entry(ct, &wf_controls, link) {
248 		if (!strcmp(ct->name, name)) {
249 			if (wf_get_control(ct))
250 				ct = NULL;
251 			mutex_unlock(&wf_lock);
252 			return ct;
253 		}
254 	}
255 	mutex_unlock(&wf_lock);
256 	return NULL;
257 }
258 EXPORT_SYMBOL_GPL(wf_find_control);
259 
260 int wf_get_control(struct wf_control *ct)
261 {
262 	if (!try_module_get(ct->ops->owner))
263 		return -ENODEV;
264 	kref_get(&ct->ref);
265 	return 0;
266 }
267 EXPORT_SYMBOL_GPL(wf_get_control);
268 
269 void wf_put_control(struct wf_control *ct)
270 {
271 	struct module *mod = ct->ops->owner;
272 	kref_put(&ct->ref, wf_control_release);
273 	module_put(mod);
274 }
275 EXPORT_SYMBOL_GPL(wf_put_control);
276 
277 
278 /*
279  * Sensors
280  */
281 
282 
283 static void wf_sensor_release(struct kref *kref)
284 {
285 	struct wf_sensor *sr = container_of(kref, struct wf_sensor, ref);
286 
287 	DBG("wf: Deleting sensor %s\n", sr->name);
288 
289 	if (sr->ops && sr->ops->release)
290 		sr->ops->release(sr);
291 	else
292 		kfree(sr);
293 }
294 
295 static ssize_t wf_show_sensor(struct device *dev,
296 			      struct device_attribute *attr, char *buf)
297 {
298 	struct wf_sensor *sens = container_of(attr, struct wf_sensor, attr);
299 	s32 val = 0;
300 	int err;
301 
302 	err = sens->ops->get_value(sens, &val);
303 	if (err < 0)
304 		return err;
305 	return sprintf(buf, "%d.%03d\n", FIX32TOPRINT(val));
306 }
307 
308 int wf_register_sensor(struct wf_sensor *new_sr)
309 {
310 	struct wf_sensor *sr;
311 
312 	mutex_lock(&wf_lock);
313 	list_for_each_entry(sr, &wf_sensors, link) {
314 		if (!strcmp(sr->name, new_sr->name)) {
315 			printk(KERN_WARNING "windfarm: trying to register"
316 			       " duplicate sensor %s\n", sr->name);
317 			mutex_unlock(&wf_lock);
318 			return -EEXIST;
319 		}
320 	}
321 	kref_init(&new_sr->ref);
322 	list_add(&new_sr->link, &wf_sensors);
323 
324 	new_sr->attr.attr.name = new_sr->name;
325 	new_sr->attr.attr.mode = 0444;
326 	new_sr->attr.show = wf_show_sensor;
327 	new_sr->attr.store = NULL;
328 	if (device_create_file(&wf_platform_device.dev, &new_sr->attr))
329 		printk(KERN_WARNING "windfarm: device_create_file failed"
330 			" for %s\n", new_sr->name);
331 		/* the subsystem still does useful work without the file */
332 
333 	DBG("wf: Registered sensor %s\n", new_sr->name);
334 
335 	wf_notify(WF_EVENT_NEW_SENSOR, new_sr);
336 	mutex_unlock(&wf_lock);
337 
338 	return 0;
339 }
340 EXPORT_SYMBOL_GPL(wf_register_sensor);
341 
342 void wf_unregister_sensor(struct wf_sensor *sr)
343 {
344 	mutex_lock(&wf_lock);
345 	list_del(&sr->link);
346 	mutex_unlock(&wf_lock);
347 
348 	DBG("wf: Unregistered sensor %s\n", sr->name);
349 
350 	wf_put_sensor(sr);
351 }
352 EXPORT_SYMBOL_GPL(wf_unregister_sensor);
353 
354 struct wf_sensor * wf_find_sensor(const char *name)
355 {
356 	struct wf_sensor *sr;
357 
358 	mutex_lock(&wf_lock);
359 	list_for_each_entry(sr, &wf_sensors, link) {
360 		if (!strcmp(sr->name, name)) {
361 			if (wf_get_sensor(sr))
362 				sr = NULL;
363 			mutex_unlock(&wf_lock);
364 			return sr;
365 		}
366 	}
367 	mutex_unlock(&wf_lock);
368 	return NULL;
369 }
370 EXPORT_SYMBOL_GPL(wf_find_sensor);
371 
372 int wf_get_sensor(struct wf_sensor *sr)
373 {
374 	if (!try_module_get(sr->ops->owner))
375 		return -ENODEV;
376 	kref_get(&sr->ref);
377 	return 0;
378 }
379 EXPORT_SYMBOL_GPL(wf_get_sensor);
380 
381 void wf_put_sensor(struct wf_sensor *sr)
382 {
383 	struct module *mod = sr->ops->owner;
384 	kref_put(&sr->ref, wf_sensor_release);
385 	module_put(mod);
386 }
387 EXPORT_SYMBOL_GPL(wf_put_sensor);
388 
389 
390 /*
391  * Client & notification
392  */
393 
394 int wf_register_client(struct notifier_block *nb)
395 {
396 	int rc;
397 	struct wf_control *ct;
398 	struct wf_sensor *sr;
399 
400 	mutex_lock(&wf_lock);
401 	rc = blocking_notifier_chain_register(&wf_client_list, nb);
402 	if (rc != 0)
403 		goto bail;
404 	wf_client_count++;
405 	list_for_each_entry(ct, &wf_controls, link)
406 		wf_notify(WF_EVENT_NEW_CONTROL, ct);
407 	list_for_each_entry(sr, &wf_sensors, link)
408 		wf_notify(WF_EVENT_NEW_SENSOR, sr);
409 	if (wf_client_count == 1)
410 		wf_start_thread();
411  bail:
412 	mutex_unlock(&wf_lock);
413 	return rc;
414 }
415 EXPORT_SYMBOL_GPL(wf_register_client);
416 
417 int wf_unregister_client(struct notifier_block *nb)
418 {
419 	mutex_lock(&wf_lock);
420 	blocking_notifier_chain_unregister(&wf_client_list, nb);
421 	wf_client_count++;
422 	if (wf_client_count == 0)
423 		wf_stop_thread();
424 	mutex_unlock(&wf_lock);
425 
426 	return 0;
427 }
428 EXPORT_SYMBOL_GPL(wf_unregister_client);
429 
430 void wf_set_overtemp(void)
431 {
432 	mutex_lock(&wf_lock);
433 	wf_overtemp++;
434 	if (wf_overtemp == 1) {
435 		printk(KERN_WARNING "windfarm: Overtemp condition detected !\n");
436 		wf_overtemp_counter = 0;
437 		wf_notify(WF_EVENT_OVERTEMP, NULL);
438 	}
439 	mutex_unlock(&wf_lock);
440 }
441 EXPORT_SYMBOL_GPL(wf_set_overtemp);
442 
443 void wf_clear_overtemp(void)
444 {
445 	mutex_lock(&wf_lock);
446 	WARN_ON(wf_overtemp == 0);
447 	if (wf_overtemp == 0) {
448 		mutex_unlock(&wf_lock);
449 		return;
450 	}
451 	wf_overtemp--;
452 	if (wf_overtemp == 0) {
453 		printk(KERN_WARNING "windfarm: Overtemp condition cleared !\n");
454 		wf_notify(WF_EVENT_NORMALTEMP, NULL);
455 	}
456 	mutex_unlock(&wf_lock);
457 }
458 EXPORT_SYMBOL_GPL(wf_clear_overtemp);
459 
460 int wf_is_overtemp(void)
461 {
462 	return (wf_overtemp != 0);
463 }
464 EXPORT_SYMBOL_GPL(wf_is_overtemp);
465 
466 static int __init windfarm_core_init(void)
467 {
468 	DBG("wf: core loaded\n");
469 
470 	/* Don't register on old machines that use therm_pm72 for now */
471 	if (machine_is_compatible("PowerMac7,2") ||
472 	    machine_is_compatible("PowerMac7,3") ||
473 	    machine_is_compatible("RackMac3,1"))
474 		return -ENODEV;
475 	platform_device_register(&wf_platform_device);
476 	return 0;
477 }
478 
479 static void __exit windfarm_core_exit(void)
480 {
481 	BUG_ON(wf_client_count != 0);
482 
483 	DBG("wf: core unloaded\n");
484 
485 	platform_device_unregister(&wf_platform_device);
486 }
487 
488 
489 module_init(windfarm_core_init);
490 module_exit(windfarm_core_exit);
491 
492 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
493 MODULE_DESCRIPTION("Core component of PowerMac thermal control");
494 MODULE_LICENSE("GPL");
495 
496