1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Windfarm PowerMac thermal control. Core
4  *
5  * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
6  *                    <benh@kernel.crashing.org>
7  *
8  * This core code tracks the list of sensors & controls, register
9  * clients, and holds the kernel thread used for control.
10  *
11  * TODO:
12  *
13  * Add some information about sensor/control type and data format to
14  * sensors/controls, and have the sysfs attribute stuff be moved
15  * generically here instead of hard coded in the platform specific
16  * driver as it us currently
17  *
18  * This however requires solving some annoying lifetime issues with
19  * sysfs which doesn't seem to have lifetime rules for struct attribute,
20  * I may have to create full features kobjects for every sensor/control
21  * instead which is a bit of an overkill imho
22  */
23 
24 #include <linux/types.h>
25 #include <linux/errno.h>
26 #include <linux/kernel.h>
27 #include <linux/slab.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 "windfarm.h"
39 
40 #define VERSION "0.2"
41 
42 #undef DEBUG
43 
44 #ifdef DEBUG
45 #define DBG(args...)	printk(args)
46 #else
47 #define DBG(args...)	do { } while(0)
48 #endif
49 
50 static LIST_HEAD(wf_controls);
51 static LIST_HEAD(wf_sensors);
52 static DEFINE_MUTEX(wf_lock);
53 static BLOCKING_NOTIFIER_HEAD(wf_client_list);
54 static int wf_client_count;
55 static unsigned int wf_overtemp;
56 static unsigned int wf_overtemp_counter;
57 static struct task_struct *wf_thread;
58 
59 static struct platform_device wf_platform_device = {
60 	.name	= "windfarm",
61 };
62 
63 /*
64  * Utilities & tick thread
65  */
66 
67 static inline void wf_notify(int event, void *param)
68 {
69 	blocking_notifier_call_chain(&wf_client_list, event, param);
70 }
71 
72 static int wf_critical_overtemp(void)
73 {
74 	static char const critical_overtemp_path[] = "/sbin/critical_overtemp";
75 	char *argv[] = { (char *)critical_overtemp_path, NULL };
76 	static char *envp[] = { "HOME=/",
77 				"TERM=linux",
78 				"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
79 				NULL };
80 
81 	return call_usermodehelper(critical_overtemp_path,
82 				   argv, envp, UMH_WAIT_EXEC);
83 }
84 
85 static int wf_thread_func(void *data)
86 {
87 	unsigned long next, delay;
88 
89 	next = jiffies;
90 
91 	DBG("wf: thread started\n");
92 
93 	set_freezable();
94 	while (!kthread_should_stop()) {
95 		try_to_freeze();
96 
97 		if (time_after_eq(jiffies, next)) {
98 			wf_notify(WF_EVENT_TICK, NULL);
99 			if (wf_overtemp) {
100 				wf_overtemp_counter++;
101 				/* 10 seconds overtemp, notify userland */
102 				if (wf_overtemp_counter > 10)
103 					wf_critical_overtemp();
104 				/* 30 seconds, shutdown */
105 				if (wf_overtemp_counter > 30) {
106 					printk(KERN_ERR "windfarm: Overtemp "
107 					       "for more than 30"
108 					       " seconds, shutting down\n");
109 					machine_power_off();
110 				}
111 			}
112 			next += HZ;
113 		}
114 
115 		delay = next - jiffies;
116 		if (delay <= HZ)
117 			schedule_timeout_interruptible(delay);
118 	}
119 
120 	DBG("wf: thread stopped\n");
121 
122 	return 0;
123 }
124 
125 static void wf_start_thread(void)
126 {
127 	wf_thread = kthread_run(wf_thread_func, NULL, "kwindfarm");
128 	if (IS_ERR(wf_thread)) {
129 		printk(KERN_ERR "windfarm: failed to create thread,err %ld\n",
130 		       PTR_ERR(wf_thread));
131 		wf_thread = NULL;
132 	}
133 }
134 
135 
136 static void wf_stop_thread(void)
137 {
138 	if (wf_thread)
139 		kthread_stop(wf_thread);
140 	wf_thread = NULL;
141 }
142 
143 /*
144  * Controls
145  */
146 
147 static void wf_control_release(struct kref *kref)
148 {
149 	struct wf_control *ct = container_of(kref, struct wf_control, ref);
150 
151 	DBG("wf: Deleting control %s\n", ct->name);
152 
153 	if (ct->ops && ct->ops->release)
154 		ct->ops->release(ct);
155 	else
156 		kfree(ct);
157 }
158 
159 static ssize_t wf_show_control(struct device *dev,
160 			       struct device_attribute *attr, char *buf)
161 {
162 	struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
163 	const char *typestr;
164 	s32 val = 0;
165 	int err;
166 
167 	err = ctrl->ops->get_value(ctrl, &val);
168 	if (err < 0) {
169 		if (err == -EFAULT)
170 			return sprintf(buf, "<HW FAULT>\n");
171 		return err;
172 	}
173 	switch(ctrl->type) {
174 	case WF_CONTROL_RPM_FAN:
175 		typestr = " RPM";
176 		break;
177 	case WF_CONTROL_PWM_FAN:
178 		typestr = " %";
179 		break;
180 	default:
181 		typestr = "";
182 	}
183 	return sprintf(buf, "%d%s\n", val, typestr);
184 }
185 
186 /* This is really only for debugging... */
187 static ssize_t wf_store_control(struct device *dev,
188 				struct device_attribute *attr,
189 				const char *buf, size_t count)
190 {
191 	struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
192 	int val;
193 	int err;
194 	char *endp;
195 
196 	val = simple_strtoul(buf, &endp, 0);
197 	while (endp < buf + count && (*endp == ' ' || *endp == '\n'))
198 		++endp;
199 	if (endp - buf < count)
200 		return -EINVAL;
201 	err = ctrl->ops->set_value(ctrl, val);
202 	if (err < 0)
203 		return err;
204 	return count;
205 }
206 
207 int wf_register_control(struct wf_control *new_ct)
208 {
209 	struct wf_control *ct;
210 
211 	mutex_lock(&wf_lock);
212 	list_for_each_entry(ct, &wf_controls, link) {
213 		if (!strcmp(ct->name, new_ct->name)) {
214 			printk(KERN_WARNING "windfarm: trying to register"
215 			       " duplicate control %s\n", ct->name);
216 			mutex_unlock(&wf_lock);
217 			return -EEXIST;
218 		}
219 	}
220 	kref_init(&new_ct->ref);
221 	list_add(&new_ct->link, &wf_controls);
222 
223 	sysfs_attr_init(&new_ct->attr.attr);
224 	new_ct->attr.attr.name = new_ct->name;
225 	new_ct->attr.attr.mode = 0644;
226 	new_ct->attr.show = wf_show_control;
227 	new_ct->attr.store = wf_store_control;
228 	if (device_create_file(&wf_platform_device.dev, &new_ct->attr))
229 		printk(KERN_WARNING "windfarm: device_create_file failed"
230 			" for %s\n", new_ct->name);
231 		/* the subsystem still does useful work without the file */
232 
233 	DBG("wf: Registered control %s\n", new_ct->name);
234 
235 	wf_notify(WF_EVENT_NEW_CONTROL, new_ct);
236 	mutex_unlock(&wf_lock);
237 
238 	return 0;
239 }
240 EXPORT_SYMBOL_GPL(wf_register_control);
241 
242 void wf_unregister_control(struct wf_control *ct)
243 {
244 	mutex_lock(&wf_lock);
245 	list_del(&ct->link);
246 	mutex_unlock(&wf_lock);
247 
248 	DBG("wf: Unregistered control %s\n", ct->name);
249 
250 	kref_put(&ct->ref, wf_control_release);
251 }
252 EXPORT_SYMBOL_GPL(wf_unregister_control);
253 
254 int wf_get_control(struct wf_control *ct)
255 {
256 	if (!try_module_get(ct->ops->owner))
257 		return -ENODEV;
258 	kref_get(&ct->ref);
259 	return 0;
260 }
261 EXPORT_SYMBOL_GPL(wf_get_control);
262 
263 void wf_put_control(struct wf_control *ct)
264 {
265 	struct module *mod = ct->ops->owner;
266 	kref_put(&ct->ref, wf_control_release);
267 	module_put(mod);
268 }
269 EXPORT_SYMBOL_GPL(wf_put_control);
270 
271 
272 /*
273  * Sensors
274  */
275 
276 
277 static void wf_sensor_release(struct kref *kref)
278 {
279 	struct wf_sensor *sr = container_of(kref, struct wf_sensor, ref);
280 
281 	DBG("wf: Deleting sensor %s\n", sr->name);
282 
283 	if (sr->ops && sr->ops->release)
284 		sr->ops->release(sr);
285 	else
286 		kfree(sr);
287 }
288 
289 static ssize_t wf_show_sensor(struct device *dev,
290 			      struct device_attribute *attr, char *buf)
291 {
292 	struct wf_sensor *sens = container_of(attr, struct wf_sensor, attr);
293 	s32 val = 0;
294 	int err;
295 
296 	err = sens->ops->get_value(sens, &val);
297 	if (err < 0)
298 		return err;
299 	return sprintf(buf, "%d.%03d\n", FIX32TOPRINT(val));
300 }
301 
302 int wf_register_sensor(struct wf_sensor *new_sr)
303 {
304 	struct wf_sensor *sr;
305 
306 	mutex_lock(&wf_lock);
307 	list_for_each_entry(sr, &wf_sensors, link) {
308 		if (!strcmp(sr->name, new_sr->name)) {
309 			printk(KERN_WARNING "windfarm: trying to register"
310 			       " duplicate sensor %s\n", sr->name);
311 			mutex_unlock(&wf_lock);
312 			return -EEXIST;
313 		}
314 	}
315 	kref_init(&new_sr->ref);
316 	list_add(&new_sr->link, &wf_sensors);
317 
318 	sysfs_attr_init(&new_sr->attr.attr);
319 	new_sr->attr.attr.name = new_sr->name;
320 	new_sr->attr.attr.mode = 0444;
321 	new_sr->attr.show = wf_show_sensor;
322 	new_sr->attr.store = NULL;
323 	if (device_create_file(&wf_platform_device.dev, &new_sr->attr))
324 		printk(KERN_WARNING "windfarm: device_create_file failed"
325 			" for %s\n", new_sr->name);
326 		/* the subsystem still does useful work without the file */
327 
328 	DBG("wf: Registered sensor %s\n", new_sr->name);
329 
330 	wf_notify(WF_EVENT_NEW_SENSOR, new_sr);
331 	mutex_unlock(&wf_lock);
332 
333 	return 0;
334 }
335 EXPORT_SYMBOL_GPL(wf_register_sensor);
336 
337 void wf_unregister_sensor(struct wf_sensor *sr)
338 {
339 	mutex_lock(&wf_lock);
340 	list_del(&sr->link);
341 	mutex_unlock(&wf_lock);
342 
343 	DBG("wf: Unregistered sensor %s\n", sr->name);
344 
345 	wf_put_sensor(sr);
346 }
347 EXPORT_SYMBOL_GPL(wf_unregister_sensor);
348 
349 int wf_get_sensor(struct wf_sensor *sr)
350 {
351 	if (!try_module_get(sr->ops->owner))
352 		return -ENODEV;
353 	kref_get(&sr->ref);
354 	return 0;
355 }
356 EXPORT_SYMBOL_GPL(wf_get_sensor);
357 
358 void wf_put_sensor(struct wf_sensor *sr)
359 {
360 	struct module *mod = sr->ops->owner;
361 	kref_put(&sr->ref, wf_sensor_release);
362 	module_put(mod);
363 }
364 EXPORT_SYMBOL_GPL(wf_put_sensor);
365 
366 
367 /*
368  * Client & notification
369  */
370 
371 int wf_register_client(struct notifier_block *nb)
372 {
373 	int rc;
374 	struct wf_control *ct;
375 	struct wf_sensor *sr;
376 
377 	mutex_lock(&wf_lock);
378 	rc = blocking_notifier_chain_register(&wf_client_list, nb);
379 	if (rc != 0)
380 		goto bail;
381 	wf_client_count++;
382 	list_for_each_entry(ct, &wf_controls, link)
383 		wf_notify(WF_EVENT_NEW_CONTROL, ct);
384 	list_for_each_entry(sr, &wf_sensors, link)
385 		wf_notify(WF_EVENT_NEW_SENSOR, sr);
386 	if (wf_client_count == 1)
387 		wf_start_thread();
388  bail:
389 	mutex_unlock(&wf_lock);
390 	return rc;
391 }
392 EXPORT_SYMBOL_GPL(wf_register_client);
393 
394 int wf_unregister_client(struct notifier_block *nb)
395 {
396 	mutex_lock(&wf_lock);
397 	blocking_notifier_chain_unregister(&wf_client_list, nb);
398 	wf_client_count--;
399 	if (wf_client_count == 0)
400 		wf_stop_thread();
401 	mutex_unlock(&wf_lock);
402 
403 	return 0;
404 }
405 EXPORT_SYMBOL_GPL(wf_unregister_client);
406 
407 void wf_set_overtemp(void)
408 {
409 	mutex_lock(&wf_lock);
410 	wf_overtemp++;
411 	if (wf_overtemp == 1) {
412 		printk(KERN_WARNING "windfarm: Overtemp condition detected !\n");
413 		wf_overtemp_counter = 0;
414 		wf_notify(WF_EVENT_OVERTEMP, NULL);
415 	}
416 	mutex_unlock(&wf_lock);
417 }
418 EXPORT_SYMBOL_GPL(wf_set_overtemp);
419 
420 void wf_clear_overtemp(void)
421 {
422 	mutex_lock(&wf_lock);
423 	WARN_ON(wf_overtemp == 0);
424 	if (wf_overtemp == 0) {
425 		mutex_unlock(&wf_lock);
426 		return;
427 	}
428 	wf_overtemp--;
429 	if (wf_overtemp == 0) {
430 		printk(KERN_WARNING "windfarm: Overtemp condition cleared !\n");
431 		wf_notify(WF_EVENT_NORMALTEMP, NULL);
432 	}
433 	mutex_unlock(&wf_lock);
434 }
435 EXPORT_SYMBOL_GPL(wf_clear_overtemp);
436 
437 static int __init windfarm_core_init(void)
438 {
439 	DBG("wf: core loaded\n");
440 
441 	platform_device_register(&wf_platform_device);
442 	return 0;
443 }
444 
445 static void __exit windfarm_core_exit(void)
446 {
447 	BUG_ON(wf_client_count != 0);
448 
449 	DBG("wf: core unloaded\n");
450 
451 	platform_device_unregister(&wf_platform_device);
452 }
453 
454 
455 module_init(windfarm_core_init);
456 module_exit(windfarm_core_exit);
457 
458 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
459 MODULE_DESCRIPTION("Core component of PowerMac thermal control");
460 MODULE_LICENSE("GPL");
461 
462