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, argv, envp, 0);
84 }
85 EXPORT_SYMBOL_GPL(wf_critical_overtemp);
86 
87 static int wf_thread_func(void *data)
88 {
89 	unsigned long next, delay;
90 
91 	next = jiffies;
92 
93 	DBG("wf: thread started\n");
94 
95 	while(!kthread_should_stop()) {
96 		if (time_after_eq(jiffies, next)) {
97 			wf_notify(WF_EVENT_TICK, NULL);
98 			if (wf_overtemp) {
99 				wf_overtemp_counter++;
100 				/* 10 seconds overtemp, notify userland */
101 				if (wf_overtemp_counter > 10)
102 					wf_critical_overtemp();
103 				/* 30 seconds, shutdown */
104 				if (wf_overtemp_counter > 30) {
105 					printk(KERN_ERR "windfarm: Overtemp "
106 					       "for more than 30"
107 					       " seconds, shutting down\n");
108 					machine_power_off();
109 				}
110 			}
111 			next += HZ;
112 		}
113 
114 		delay = next - jiffies;
115 		if (delay <= HZ)
116 			schedule_timeout_interruptible(delay);
117 
118 		/* there should be no non-suspend signal, but oh well */
119 		if (signal_pending(current) && !try_to_freeze()) {
120 			printk(KERN_WARNING "windfarm: thread got sigl !\n");
121 			break;
122 		}
123 	}
124 
125 	DBG("wf: thread stopped\n");
126 
127 	return 0;
128 }
129 
130 static void wf_start_thread(void)
131 {
132 	wf_thread = kthread_run(wf_thread_func, NULL, "kwindfarm");
133 	if (IS_ERR(wf_thread)) {
134 		printk(KERN_ERR "windfarm: failed to create thread,err %ld\n",
135 		       PTR_ERR(wf_thread));
136 		wf_thread = NULL;
137 	}
138 }
139 
140 
141 static void wf_stop_thread(void)
142 {
143 	if (wf_thread)
144 		kthread_stop(wf_thread);
145 	wf_thread = NULL;
146 }
147 
148 /*
149  * Controls
150  */
151 
152 static void wf_control_release(struct kref *kref)
153 {
154 	struct wf_control *ct = container_of(kref, struct wf_control, ref);
155 
156 	DBG("wf: Deleting control %s\n", ct->name);
157 
158 	if (ct->ops && ct->ops->release)
159 		ct->ops->release(ct);
160 	else
161 		kfree(ct);
162 }
163 
164 static ssize_t wf_show_control(struct device *dev,
165 			       struct device_attribute *attr, char *buf)
166 {
167 	struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
168 	s32 val = 0;
169 	int err;
170 
171 	err = ctrl->ops->get_value(ctrl, &val);
172 	if (err < 0)
173 		return err;
174 	return sprintf(buf, "%d\n", val);
175 }
176 
177 /* This is really only for debugging... */
178 static ssize_t wf_store_control(struct device *dev,
179 				struct device_attribute *attr,
180 				const char *buf, size_t count)
181 {
182 	struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
183 	int val;
184 	int err;
185 	char *endp;
186 
187 	val = simple_strtoul(buf, &endp, 0);
188 	while (endp < buf + count && (*endp == ' ' || *endp == '\n'))
189 		++endp;
190 	if (endp - buf < count)
191 		return -EINVAL;
192 	err = ctrl->ops->set_value(ctrl, val);
193 	if (err < 0)
194 		return err;
195 	return count;
196 }
197 
198 int wf_register_control(struct wf_control *new_ct)
199 {
200 	struct wf_control *ct;
201 
202 	mutex_lock(&wf_lock);
203 	list_for_each_entry(ct, &wf_controls, link) {
204 		if (!strcmp(ct->name, new_ct->name)) {
205 			printk(KERN_WARNING "windfarm: trying to register"
206 			       " duplicate control %s\n", ct->name);
207 			mutex_unlock(&wf_lock);
208 			return -EEXIST;
209 		}
210 	}
211 	kref_init(&new_ct->ref);
212 	list_add(&new_ct->link, &wf_controls);
213 
214 	new_ct->attr.attr.name = new_ct->name;
215 	new_ct->attr.attr.owner = THIS_MODULE;
216 	new_ct->attr.attr.mode = 0644;
217 	new_ct->attr.show = wf_show_control;
218 	new_ct->attr.store = wf_store_control;
219 	if (device_create_file(&wf_platform_device.dev, &new_ct->attr))
220 		printk(KERN_WARNING "windfarm: device_create_file failed"
221 			" for %s\n", new_ct->name);
222 		/* the subsystem still does useful work without the file */
223 
224 	DBG("wf: Registered control %s\n", new_ct->name);
225 
226 	wf_notify(WF_EVENT_NEW_CONTROL, new_ct);
227 	mutex_unlock(&wf_lock);
228 
229 	return 0;
230 }
231 EXPORT_SYMBOL_GPL(wf_register_control);
232 
233 void wf_unregister_control(struct wf_control *ct)
234 {
235 	mutex_lock(&wf_lock);
236 	list_del(&ct->link);
237 	mutex_unlock(&wf_lock);
238 
239 	DBG("wf: Unregistered control %s\n", ct->name);
240 
241 	kref_put(&ct->ref, wf_control_release);
242 }
243 EXPORT_SYMBOL_GPL(wf_unregister_control);
244 
245 struct wf_control * wf_find_control(const char *name)
246 {
247 	struct wf_control *ct;
248 
249 	mutex_lock(&wf_lock);
250 	list_for_each_entry(ct, &wf_controls, link) {
251 		if (!strcmp(ct->name, name)) {
252 			if (wf_get_control(ct))
253 				ct = NULL;
254 			mutex_unlock(&wf_lock);
255 			return ct;
256 		}
257 	}
258 	mutex_unlock(&wf_lock);
259 	return NULL;
260 }
261 EXPORT_SYMBOL_GPL(wf_find_control);
262 
263 int wf_get_control(struct wf_control *ct)
264 {
265 	if (!try_module_get(ct->ops->owner))
266 		return -ENODEV;
267 	kref_get(&ct->ref);
268 	return 0;
269 }
270 EXPORT_SYMBOL_GPL(wf_get_control);
271 
272 void wf_put_control(struct wf_control *ct)
273 {
274 	struct module *mod = ct->ops->owner;
275 	kref_put(&ct->ref, wf_control_release);
276 	module_put(mod);
277 }
278 EXPORT_SYMBOL_GPL(wf_put_control);
279 
280 
281 /*
282  * Sensors
283  */
284 
285 
286 static void wf_sensor_release(struct kref *kref)
287 {
288 	struct wf_sensor *sr = container_of(kref, struct wf_sensor, ref);
289 
290 	DBG("wf: Deleting sensor %s\n", sr->name);
291 
292 	if (sr->ops && sr->ops->release)
293 		sr->ops->release(sr);
294 	else
295 		kfree(sr);
296 }
297 
298 static ssize_t wf_show_sensor(struct device *dev,
299 			      struct device_attribute *attr, char *buf)
300 {
301 	struct wf_sensor *sens = container_of(attr, struct wf_sensor, attr);
302 	s32 val = 0;
303 	int err;
304 
305 	err = sens->ops->get_value(sens, &val);
306 	if (err < 0)
307 		return err;
308 	return sprintf(buf, "%d.%03d\n", FIX32TOPRINT(val));
309 }
310 
311 int wf_register_sensor(struct wf_sensor *new_sr)
312 {
313 	struct wf_sensor *sr;
314 
315 	mutex_lock(&wf_lock);
316 	list_for_each_entry(sr, &wf_sensors, link) {
317 		if (!strcmp(sr->name, new_sr->name)) {
318 			printk(KERN_WARNING "windfarm: trying to register"
319 			       " duplicate sensor %s\n", sr->name);
320 			mutex_unlock(&wf_lock);
321 			return -EEXIST;
322 		}
323 	}
324 	kref_init(&new_sr->ref);
325 	list_add(&new_sr->link, &wf_sensors);
326 
327 	new_sr->attr.attr.name = new_sr->name;
328 	new_sr->attr.attr.owner = THIS_MODULE;
329 	new_sr->attr.attr.mode = 0444;
330 	new_sr->attr.show = wf_show_sensor;
331 	new_sr->attr.store = NULL;
332 	if (device_create_file(&wf_platform_device.dev, &new_sr->attr))
333 		printk(KERN_WARNING "windfarm: device_create_file failed"
334 			" for %s\n", new_sr->name);
335 		/* the subsystem still does useful work without the file */
336 
337 	DBG("wf: Registered sensor %s\n", new_sr->name);
338 
339 	wf_notify(WF_EVENT_NEW_SENSOR, new_sr);
340 	mutex_unlock(&wf_lock);
341 
342 	return 0;
343 }
344 EXPORT_SYMBOL_GPL(wf_register_sensor);
345 
346 void wf_unregister_sensor(struct wf_sensor *sr)
347 {
348 	mutex_lock(&wf_lock);
349 	list_del(&sr->link);
350 	mutex_unlock(&wf_lock);
351 
352 	DBG("wf: Unregistered sensor %s\n", sr->name);
353 
354 	wf_put_sensor(sr);
355 }
356 EXPORT_SYMBOL_GPL(wf_unregister_sensor);
357 
358 struct wf_sensor * wf_find_sensor(const char *name)
359 {
360 	struct wf_sensor *sr;
361 
362 	mutex_lock(&wf_lock);
363 	list_for_each_entry(sr, &wf_sensors, link) {
364 		if (!strcmp(sr->name, name)) {
365 			if (wf_get_sensor(sr))
366 				sr = NULL;
367 			mutex_unlock(&wf_lock);
368 			return sr;
369 		}
370 	}
371 	mutex_unlock(&wf_lock);
372 	return NULL;
373 }
374 EXPORT_SYMBOL_GPL(wf_find_sensor);
375 
376 int wf_get_sensor(struct wf_sensor *sr)
377 {
378 	if (!try_module_get(sr->ops->owner))
379 		return -ENODEV;
380 	kref_get(&sr->ref);
381 	return 0;
382 }
383 EXPORT_SYMBOL_GPL(wf_get_sensor);
384 
385 void wf_put_sensor(struct wf_sensor *sr)
386 {
387 	struct module *mod = sr->ops->owner;
388 	kref_put(&sr->ref, wf_sensor_release);
389 	module_put(mod);
390 }
391 EXPORT_SYMBOL_GPL(wf_put_sensor);
392 
393 
394 /*
395  * Client & notification
396  */
397 
398 int wf_register_client(struct notifier_block *nb)
399 {
400 	int rc;
401 	struct wf_control *ct;
402 	struct wf_sensor *sr;
403 
404 	mutex_lock(&wf_lock);
405 	rc = blocking_notifier_chain_register(&wf_client_list, nb);
406 	if (rc != 0)
407 		goto bail;
408 	wf_client_count++;
409 	list_for_each_entry(ct, &wf_controls, link)
410 		wf_notify(WF_EVENT_NEW_CONTROL, ct);
411 	list_for_each_entry(sr, &wf_sensors, link)
412 		wf_notify(WF_EVENT_NEW_SENSOR, sr);
413 	if (wf_client_count == 1)
414 		wf_start_thread();
415  bail:
416 	mutex_unlock(&wf_lock);
417 	return rc;
418 }
419 EXPORT_SYMBOL_GPL(wf_register_client);
420 
421 int wf_unregister_client(struct notifier_block *nb)
422 {
423 	mutex_lock(&wf_lock);
424 	blocking_notifier_chain_unregister(&wf_client_list, nb);
425 	wf_client_count++;
426 	if (wf_client_count == 0)
427 		wf_stop_thread();
428 	mutex_unlock(&wf_lock);
429 
430 	return 0;
431 }
432 EXPORT_SYMBOL_GPL(wf_unregister_client);
433 
434 void wf_set_overtemp(void)
435 {
436 	mutex_lock(&wf_lock);
437 	wf_overtemp++;
438 	if (wf_overtemp == 1) {
439 		printk(KERN_WARNING "windfarm: Overtemp condition detected !\n");
440 		wf_overtemp_counter = 0;
441 		wf_notify(WF_EVENT_OVERTEMP, NULL);
442 	}
443 	mutex_unlock(&wf_lock);
444 }
445 EXPORT_SYMBOL_GPL(wf_set_overtemp);
446 
447 void wf_clear_overtemp(void)
448 {
449 	mutex_lock(&wf_lock);
450 	WARN_ON(wf_overtemp == 0);
451 	if (wf_overtemp == 0) {
452 		mutex_unlock(&wf_lock);
453 		return;
454 	}
455 	wf_overtemp--;
456 	if (wf_overtemp == 0) {
457 		printk(KERN_WARNING "windfarm: Overtemp condition cleared !\n");
458 		wf_notify(WF_EVENT_NORMALTEMP, NULL);
459 	}
460 	mutex_unlock(&wf_lock);
461 }
462 EXPORT_SYMBOL_GPL(wf_clear_overtemp);
463 
464 int wf_is_overtemp(void)
465 {
466 	return (wf_overtemp != 0);
467 }
468 EXPORT_SYMBOL_GPL(wf_is_overtemp);
469 
470 static int __init windfarm_core_init(void)
471 {
472 	DBG("wf: core loaded\n");
473 
474 	/* Don't register on old machines that use therm_pm72 for now */
475 	if (machine_is_compatible("PowerMac7,2") ||
476 	    machine_is_compatible("PowerMac7,3") ||
477 	    machine_is_compatible("RackMac3,1"))
478 		return -ENODEV;
479 	platform_device_register(&wf_platform_device);
480 	return 0;
481 }
482 
483 static void __exit windfarm_core_exit(void)
484 {
485 	BUG_ON(wf_client_count != 0);
486 
487 	DBG("wf: core unloaded\n");
488 
489 	platform_device_unregister(&wf_platform_device);
490 }
491 
492 
493 module_init(windfarm_core_init);
494 module_exit(windfarm_core_exit);
495 
496 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
497 MODULE_DESCRIPTION("Core component of PowerMac thermal control");
498 MODULE_LICENSE("GPL");
499 
500