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 	s32 val = 0;
168 	int err;
169 
170 	err = ctrl->ops->get_value(ctrl, &val);
171 	if (err < 0)
172 		return err;
173 	return sprintf(buf, "%d\n", val);
174 }
175 
176 /* This is really only for debugging... */
177 static ssize_t wf_store_control(struct device *dev,
178 				struct device_attribute *attr,
179 				const char *buf, size_t count)
180 {
181 	struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
182 	int val;
183 	int err;
184 	char *endp;
185 
186 	val = simple_strtoul(buf, &endp, 0);
187 	while (endp < buf + count && (*endp == ' ' || *endp == '\n'))
188 		++endp;
189 	if (endp - buf < count)
190 		return -EINVAL;
191 	err = ctrl->ops->set_value(ctrl, val);
192 	if (err < 0)
193 		return err;
194 	return count;
195 }
196 
197 int wf_register_control(struct wf_control *new_ct)
198 {
199 	struct wf_control *ct;
200 
201 	mutex_lock(&wf_lock);
202 	list_for_each_entry(ct, &wf_controls, link) {
203 		if (!strcmp(ct->name, new_ct->name)) {
204 			printk(KERN_WARNING "windfarm: trying to register"
205 			       " duplicate control %s\n", ct->name);
206 			mutex_unlock(&wf_lock);
207 			return -EEXIST;
208 		}
209 	}
210 	kref_init(&new_ct->ref);
211 	list_add(&new_ct->link, &wf_controls);
212 
213 	sysfs_attr_init(&new_ct->attr.attr);
214 	new_ct->attr.attr.name = new_ct->name;
215 	new_ct->attr.attr.mode = 0644;
216 	new_ct->attr.show = wf_show_control;
217 	new_ct->attr.store = wf_store_control;
218 	if (device_create_file(&wf_platform_device.dev, &new_ct->attr))
219 		printk(KERN_WARNING "windfarm: device_create_file failed"
220 			" for %s\n", new_ct->name);
221 		/* the subsystem still does useful work without the file */
222 
223 	DBG("wf: Registered control %s\n", new_ct->name);
224 
225 	wf_notify(WF_EVENT_NEW_CONTROL, new_ct);
226 	mutex_unlock(&wf_lock);
227 
228 	return 0;
229 }
230 EXPORT_SYMBOL_GPL(wf_register_control);
231 
232 void wf_unregister_control(struct wf_control *ct)
233 {
234 	mutex_lock(&wf_lock);
235 	list_del(&ct->link);
236 	mutex_unlock(&wf_lock);
237 
238 	DBG("wf: Unregistered control %s\n", ct->name);
239 
240 	kref_put(&ct->ref, wf_control_release);
241 }
242 EXPORT_SYMBOL_GPL(wf_unregister_control);
243 
244 struct wf_control * wf_find_control(const char *name)
245 {
246 	struct wf_control *ct;
247 
248 	mutex_lock(&wf_lock);
249 	list_for_each_entry(ct, &wf_controls, link) {
250 		if (!strcmp(ct->name, name)) {
251 			if (wf_get_control(ct))
252 				ct = NULL;
253 			mutex_unlock(&wf_lock);
254 			return ct;
255 		}
256 	}
257 	mutex_unlock(&wf_lock);
258 	return NULL;
259 }
260 EXPORT_SYMBOL_GPL(wf_find_control);
261 
262 int wf_get_control(struct wf_control *ct)
263 {
264 	if (!try_module_get(ct->ops->owner))
265 		return -ENODEV;
266 	kref_get(&ct->ref);
267 	return 0;
268 }
269 EXPORT_SYMBOL_GPL(wf_get_control);
270 
271 void wf_put_control(struct wf_control *ct)
272 {
273 	struct module *mod = ct->ops->owner;
274 	kref_put(&ct->ref, wf_control_release);
275 	module_put(mod);
276 }
277 EXPORT_SYMBOL_GPL(wf_put_control);
278 
279 
280 /*
281  * Sensors
282  */
283 
284 
285 static void wf_sensor_release(struct kref *kref)
286 {
287 	struct wf_sensor *sr = container_of(kref, struct wf_sensor, ref);
288 
289 	DBG("wf: Deleting sensor %s\n", sr->name);
290 
291 	if (sr->ops && sr->ops->release)
292 		sr->ops->release(sr);
293 	else
294 		kfree(sr);
295 }
296 
297 static ssize_t wf_show_sensor(struct device *dev,
298 			      struct device_attribute *attr, char *buf)
299 {
300 	struct wf_sensor *sens = container_of(attr, struct wf_sensor, attr);
301 	s32 val = 0;
302 	int err;
303 
304 	err = sens->ops->get_value(sens, &val);
305 	if (err < 0)
306 		return err;
307 	return sprintf(buf, "%d.%03d\n", FIX32TOPRINT(val));
308 }
309 
310 int wf_register_sensor(struct wf_sensor *new_sr)
311 {
312 	struct wf_sensor *sr;
313 
314 	mutex_lock(&wf_lock);
315 	list_for_each_entry(sr, &wf_sensors, link) {
316 		if (!strcmp(sr->name, new_sr->name)) {
317 			printk(KERN_WARNING "windfarm: trying to register"
318 			       " duplicate sensor %s\n", sr->name);
319 			mutex_unlock(&wf_lock);
320 			return -EEXIST;
321 		}
322 	}
323 	kref_init(&new_sr->ref);
324 	list_add(&new_sr->link, &wf_sensors);
325 
326 	sysfs_attr_init(&new_sr->attr.attr);
327 	new_sr->attr.attr.name = new_sr->name;
328 	new_sr->attr.attr.mode = 0444;
329 	new_sr->attr.show = wf_show_sensor;
330 	new_sr->attr.store = NULL;
331 	if (device_create_file(&wf_platform_device.dev, &new_sr->attr))
332 		printk(KERN_WARNING "windfarm: device_create_file failed"
333 			" for %s\n", new_sr->name);
334 		/* the subsystem still does useful work without the file */
335 
336 	DBG("wf: Registered sensor %s\n", new_sr->name);
337 
338 	wf_notify(WF_EVENT_NEW_SENSOR, new_sr);
339 	mutex_unlock(&wf_lock);
340 
341 	return 0;
342 }
343 EXPORT_SYMBOL_GPL(wf_register_sensor);
344 
345 void wf_unregister_sensor(struct wf_sensor *sr)
346 {
347 	mutex_lock(&wf_lock);
348 	list_del(&sr->link);
349 	mutex_unlock(&wf_lock);
350 
351 	DBG("wf: Unregistered sensor %s\n", sr->name);
352 
353 	wf_put_sensor(sr);
354 }
355 EXPORT_SYMBOL_GPL(wf_unregister_sensor);
356 
357 struct wf_sensor * wf_find_sensor(const char *name)
358 {
359 	struct wf_sensor *sr;
360 
361 	mutex_lock(&wf_lock);
362 	list_for_each_entry(sr, &wf_sensors, link) {
363 		if (!strcmp(sr->name, name)) {
364 			if (wf_get_sensor(sr))
365 				sr = NULL;
366 			mutex_unlock(&wf_lock);
367 			return sr;
368 		}
369 	}
370 	mutex_unlock(&wf_lock);
371 	return NULL;
372 }
373 EXPORT_SYMBOL_GPL(wf_find_sensor);
374 
375 int wf_get_sensor(struct wf_sensor *sr)
376 {
377 	if (!try_module_get(sr->ops->owner))
378 		return -ENODEV;
379 	kref_get(&sr->ref);
380 	return 0;
381 }
382 EXPORT_SYMBOL_GPL(wf_get_sensor);
383 
384 void wf_put_sensor(struct wf_sensor *sr)
385 {
386 	struct module *mod = sr->ops->owner;
387 	kref_put(&sr->ref, wf_sensor_release);
388 	module_put(mod);
389 }
390 EXPORT_SYMBOL_GPL(wf_put_sensor);
391 
392 
393 /*
394  * Client & notification
395  */
396 
397 int wf_register_client(struct notifier_block *nb)
398 {
399 	int rc;
400 	struct wf_control *ct;
401 	struct wf_sensor *sr;
402 
403 	mutex_lock(&wf_lock);
404 	rc = blocking_notifier_chain_register(&wf_client_list, nb);
405 	if (rc != 0)
406 		goto bail;
407 	wf_client_count++;
408 	list_for_each_entry(ct, &wf_controls, link)
409 		wf_notify(WF_EVENT_NEW_CONTROL, ct);
410 	list_for_each_entry(sr, &wf_sensors, link)
411 		wf_notify(WF_EVENT_NEW_SENSOR, sr);
412 	if (wf_client_count == 1)
413 		wf_start_thread();
414  bail:
415 	mutex_unlock(&wf_lock);
416 	return rc;
417 }
418 EXPORT_SYMBOL_GPL(wf_register_client);
419 
420 int wf_unregister_client(struct notifier_block *nb)
421 {
422 	mutex_lock(&wf_lock);
423 	blocking_notifier_chain_unregister(&wf_client_list, nb);
424 	wf_client_count++;
425 	if (wf_client_count == 0)
426 		wf_stop_thread();
427 	mutex_unlock(&wf_lock);
428 
429 	return 0;
430 }
431 EXPORT_SYMBOL_GPL(wf_unregister_client);
432 
433 void wf_set_overtemp(void)
434 {
435 	mutex_lock(&wf_lock);
436 	wf_overtemp++;
437 	if (wf_overtemp == 1) {
438 		printk(KERN_WARNING "windfarm: Overtemp condition detected !\n");
439 		wf_overtemp_counter = 0;
440 		wf_notify(WF_EVENT_OVERTEMP, NULL);
441 	}
442 	mutex_unlock(&wf_lock);
443 }
444 EXPORT_SYMBOL_GPL(wf_set_overtemp);
445 
446 void wf_clear_overtemp(void)
447 {
448 	mutex_lock(&wf_lock);
449 	WARN_ON(wf_overtemp == 0);
450 	if (wf_overtemp == 0) {
451 		mutex_unlock(&wf_lock);
452 		return;
453 	}
454 	wf_overtemp--;
455 	if (wf_overtemp == 0) {
456 		printk(KERN_WARNING "windfarm: Overtemp condition cleared !\n");
457 		wf_notify(WF_EVENT_NORMALTEMP, NULL);
458 	}
459 	mutex_unlock(&wf_lock);
460 }
461 EXPORT_SYMBOL_GPL(wf_clear_overtemp);
462 
463 int wf_is_overtemp(void)
464 {
465 	return (wf_overtemp != 0);
466 }
467 EXPORT_SYMBOL_GPL(wf_is_overtemp);
468 
469 static int __init windfarm_core_init(void)
470 {
471 	DBG("wf: core loaded\n");
472 
473 	/* Don't register on old machines that use therm_pm72 for now */
474 	if (of_machine_is_compatible("PowerMac7,2") ||
475 	    of_machine_is_compatible("PowerMac7,3") ||
476 	    of_machine_is_compatible("RackMac3,1"))
477 		return -ENODEV;
478 	platform_device_register(&wf_platform_device);
479 	return 0;
480 }
481 
482 static void __exit windfarm_core_exit(void)
483 {
484 	BUG_ON(wf_client_count != 0);
485 
486 	DBG("wf: core unloaded\n");
487 
488 	platform_device_unregister(&wf_platform_device);
489 }
490 
491 
492 module_init(windfarm_core_init);
493 module_exit(windfarm_core_exit);
494 
495 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
496 MODULE_DESCRIPTION("Core component of PowerMac thermal control");
497 MODULE_LICENSE("GPL");
498 
499