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 <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 static 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 static int wf_critical_overtemp(void)
75 {
76 	static char const critical_overtemp_path[] = "/sbin/critical_overtemp";
77 	char *argv[] = { (char *)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 
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 	set_freezable();
96 	while (!kthread_should_stop()) {
97 		try_to_freeze();
98 
99 		if (time_after_eq(jiffies, next)) {
100 			wf_notify(WF_EVENT_TICK, NULL);
101 			if (wf_overtemp) {
102 				wf_overtemp_counter++;
103 				/* 10 seconds overtemp, notify userland */
104 				if (wf_overtemp_counter > 10)
105 					wf_critical_overtemp();
106 				/* 30 seconds, shutdown */
107 				if (wf_overtemp_counter > 30) {
108 					printk(KERN_ERR "windfarm: Overtemp "
109 					       "for more than 30"
110 					       " seconds, shutting down\n");
111 					machine_power_off();
112 				}
113 			}
114 			next += HZ;
115 		}
116 
117 		delay = next - jiffies;
118 		if (delay <= HZ)
119 			schedule_timeout_interruptible(delay);
120 	}
121 
122 	DBG("wf: thread stopped\n");
123 
124 	return 0;
125 }
126 
127 static void wf_start_thread(void)
128 {
129 	wf_thread = kthread_run(wf_thread_func, NULL, "kwindfarm");
130 	if (IS_ERR(wf_thread)) {
131 		printk(KERN_ERR "windfarm: failed to create thread,err %ld\n",
132 		       PTR_ERR(wf_thread));
133 		wf_thread = NULL;
134 	}
135 }
136 
137 
138 static void wf_stop_thread(void)
139 {
140 	if (wf_thread)
141 		kthread_stop(wf_thread);
142 	wf_thread = NULL;
143 }
144 
145 /*
146  * Controls
147  */
148 
149 static void wf_control_release(struct kref *kref)
150 {
151 	struct wf_control *ct = container_of(kref, struct wf_control, ref);
152 
153 	DBG("wf: Deleting control %s\n", ct->name);
154 
155 	if (ct->ops && ct->ops->release)
156 		ct->ops->release(ct);
157 	else
158 		kfree(ct);
159 }
160 
161 static ssize_t wf_show_control(struct device *dev,
162 			       struct device_attribute *attr, char *buf)
163 {
164 	struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
165 	const char *typestr;
166 	s32 val = 0;
167 	int err;
168 
169 	err = ctrl->ops->get_value(ctrl, &val);
170 	if (err < 0) {
171 		if (err == -EFAULT)
172 			return sprintf(buf, "<HW FAULT>\n");
173 		return err;
174 	}
175 	switch(ctrl->type) {
176 	case WF_CONTROL_RPM_FAN:
177 		typestr = " RPM";
178 		break;
179 	case WF_CONTROL_PWM_FAN:
180 		typestr = " %";
181 		break;
182 	default:
183 		typestr = "";
184 	}
185 	return sprintf(buf, "%d%s\n", val, typestr);
186 }
187 
188 /* This is really only for debugging... */
189 static ssize_t wf_store_control(struct device *dev,
190 				struct device_attribute *attr,
191 				const char *buf, size_t count)
192 {
193 	struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
194 	int val;
195 	int err;
196 	char *endp;
197 
198 	val = simple_strtoul(buf, &endp, 0);
199 	while (endp < buf + count && (*endp == ' ' || *endp == '\n'))
200 		++endp;
201 	if (endp - buf < count)
202 		return -EINVAL;
203 	err = ctrl->ops->set_value(ctrl, val);
204 	if (err < 0)
205 		return err;
206 	return count;
207 }
208 
209 int wf_register_control(struct wf_control *new_ct)
210 {
211 	struct wf_control *ct;
212 
213 	mutex_lock(&wf_lock);
214 	list_for_each_entry(ct, &wf_controls, link) {
215 		if (!strcmp(ct->name, new_ct->name)) {
216 			printk(KERN_WARNING "windfarm: trying to register"
217 			       " duplicate control %s\n", ct->name);
218 			mutex_unlock(&wf_lock);
219 			return -EEXIST;
220 		}
221 	}
222 	kref_init(&new_ct->ref);
223 	list_add(&new_ct->link, &wf_controls);
224 
225 	sysfs_attr_init(&new_ct->attr.attr);
226 	new_ct->attr.attr.name = new_ct->name;
227 	new_ct->attr.attr.mode = 0644;
228 	new_ct->attr.show = wf_show_control;
229 	new_ct->attr.store = wf_store_control;
230 	if (device_create_file(&wf_platform_device.dev, &new_ct->attr))
231 		printk(KERN_WARNING "windfarm: device_create_file failed"
232 			" for %s\n", new_ct->name);
233 		/* the subsystem still does useful work without the file */
234 
235 	DBG("wf: Registered control %s\n", new_ct->name);
236 
237 	wf_notify(WF_EVENT_NEW_CONTROL, new_ct);
238 	mutex_unlock(&wf_lock);
239 
240 	return 0;
241 }
242 EXPORT_SYMBOL_GPL(wf_register_control);
243 
244 void wf_unregister_control(struct wf_control *ct)
245 {
246 	mutex_lock(&wf_lock);
247 	list_del(&ct->link);
248 	mutex_unlock(&wf_lock);
249 
250 	DBG("wf: Unregistered control %s\n", ct->name);
251 
252 	kref_put(&ct->ref, wf_control_release);
253 }
254 EXPORT_SYMBOL_GPL(wf_unregister_control);
255 
256 int wf_get_control(struct wf_control *ct)
257 {
258 	if (!try_module_get(ct->ops->owner))
259 		return -ENODEV;
260 	kref_get(&ct->ref);
261 	return 0;
262 }
263 EXPORT_SYMBOL_GPL(wf_get_control);
264 
265 void wf_put_control(struct wf_control *ct)
266 {
267 	struct module *mod = ct->ops->owner;
268 	kref_put(&ct->ref, wf_control_release);
269 	module_put(mod);
270 }
271 EXPORT_SYMBOL_GPL(wf_put_control);
272 
273 
274 /*
275  * Sensors
276  */
277 
278 
279 static void wf_sensor_release(struct kref *kref)
280 {
281 	struct wf_sensor *sr = container_of(kref, struct wf_sensor, ref);
282 
283 	DBG("wf: Deleting sensor %s\n", sr->name);
284 
285 	if (sr->ops && sr->ops->release)
286 		sr->ops->release(sr);
287 	else
288 		kfree(sr);
289 }
290 
291 static ssize_t wf_show_sensor(struct device *dev,
292 			      struct device_attribute *attr, char *buf)
293 {
294 	struct wf_sensor *sens = container_of(attr, struct wf_sensor, attr);
295 	s32 val = 0;
296 	int err;
297 
298 	err = sens->ops->get_value(sens, &val);
299 	if (err < 0)
300 		return err;
301 	return sprintf(buf, "%d.%03d\n", FIX32TOPRINT(val));
302 }
303 
304 int wf_register_sensor(struct wf_sensor *new_sr)
305 {
306 	struct wf_sensor *sr;
307 
308 	mutex_lock(&wf_lock);
309 	list_for_each_entry(sr, &wf_sensors, link) {
310 		if (!strcmp(sr->name, new_sr->name)) {
311 			printk(KERN_WARNING "windfarm: trying to register"
312 			       " duplicate sensor %s\n", sr->name);
313 			mutex_unlock(&wf_lock);
314 			return -EEXIST;
315 		}
316 	}
317 	kref_init(&new_sr->ref);
318 	list_add(&new_sr->link, &wf_sensors);
319 
320 	sysfs_attr_init(&new_sr->attr.attr);
321 	new_sr->attr.attr.name = new_sr->name;
322 	new_sr->attr.attr.mode = 0444;
323 	new_sr->attr.show = wf_show_sensor;
324 	new_sr->attr.store = NULL;
325 	if (device_create_file(&wf_platform_device.dev, &new_sr->attr))
326 		printk(KERN_WARNING "windfarm: device_create_file failed"
327 			" for %s\n", new_sr->name);
328 		/* the subsystem still does useful work without the file */
329 
330 	DBG("wf: Registered sensor %s\n", new_sr->name);
331 
332 	wf_notify(WF_EVENT_NEW_SENSOR, new_sr);
333 	mutex_unlock(&wf_lock);
334 
335 	return 0;
336 }
337 EXPORT_SYMBOL_GPL(wf_register_sensor);
338 
339 void wf_unregister_sensor(struct wf_sensor *sr)
340 {
341 	mutex_lock(&wf_lock);
342 	list_del(&sr->link);
343 	mutex_unlock(&wf_lock);
344 
345 	DBG("wf: Unregistered sensor %s\n", sr->name);
346 
347 	wf_put_sensor(sr);
348 }
349 EXPORT_SYMBOL_GPL(wf_unregister_sensor);
350 
351 int wf_get_sensor(struct wf_sensor *sr)
352 {
353 	if (!try_module_get(sr->ops->owner))
354 		return -ENODEV;
355 	kref_get(&sr->ref);
356 	return 0;
357 }
358 EXPORT_SYMBOL_GPL(wf_get_sensor);
359 
360 void wf_put_sensor(struct wf_sensor *sr)
361 {
362 	struct module *mod = sr->ops->owner;
363 	kref_put(&sr->ref, wf_sensor_release);
364 	module_put(mod);
365 }
366 EXPORT_SYMBOL_GPL(wf_put_sensor);
367 
368 
369 /*
370  * Client & notification
371  */
372 
373 int wf_register_client(struct notifier_block *nb)
374 {
375 	int rc;
376 	struct wf_control *ct;
377 	struct wf_sensor *sr;
378 
379 	mutex_lock(&wf_lock);
380 	rc = blocking_notifier_chain_register(&wf_client_list, nb);
381 	if (rc != 0)
382 		goto bail;
383 	wf_client_count++;
384 	list_for_each_entry(ct, &wf_controls, link)
385 		wf_notify(WF_EVENT_NEW_CONTROL, ct);
386 	list_for_each_entry(sr, &wf_sensors, link)
387 		wf_notify(WF_EVENT_NEW_SENSOR, sr);
388 	if (wf_client_count == 1)
389 		wf_start_thread();
390  bail:
391 	mutex_unlock(&wf_lock);
392 	return rc;
393 }
394 EXPORT_SYMBOL_GPL(wf_register_client);
395 
396 int wf_unregister_client(struct notifier_block *nb)
397 {
398 	mutex_lock(&wf_lock);
399 	blocking_notifier_chain_unregister(&wf_client_list, nb);
400 	wf_client_count--;
401 	if (wf_client_count == 0)
402 		wf_stop_thread();
403 	mutex_unlock(&wf_lock);
404 
405 	return 0;
406 }
407 EXPORT_SYMBOL_GPL(wf_unregister_client);
408 
409 void wf_set_overtemp(void)
410 {
411 	mutex_lock(&wf_lock);
412 	wf_overtemp++;
413 	if (wf_overtemp == 1) {
414 		printk(KERN_WARNING "windfarm: Overtemp condition detected !\n");
415 		wf_overtemp_counter = 0;
416 		wf_notify(WF_EVENT_OVERTEMP, NULL);
417 	}
418 	mutex_unlock(&wf_lock);
419 }
420 EXPORT_SYMBOL_GPL(wf_set_overtemp);
421 
422 void wf_clear_overtemp(void)
423 {
424 	mutex_lock(&wf_lock);
425 	WARN_ON(wf_overtemp == 0);
426 	if (wf_overtemp == 0) {
427 		mutex_unlock(&wf_lock);
428 		return;
429 	}
430 	wf_overtemp--;
431 	if (wf_overtemp == 0) {
432 		printk(KERN_WARNING "windfarm: Overtemp condition cleared !\n");
433 		wf_notify(WF_EVENT_NORMALTEMP, NULL);
434 	}
435 	mutex_unlock(&wf_lock);
436 }
437 EXPORT_SYMBOL_GPL(wf_clear_overtemp);
438 
439 static int __init windfarm_core_init(void)
440 {
441 	DBG("wf: core loaded\n");
442 
443 	platform_device_register(&wf_platform_device);
444 	return 0;
445 }
446 
447 static void __exit windfarm_core_exit(void)
448 {
449 	BUG_ON(wf_client_count != 0);
450 
451 	DBG("wf: core unloaded\n");
452 
453 	platform_device_unregister(&wf_platform_device);
454 }
455 
456 
457 module_init(windfarm_core_init);
458 module_exit(windfarm_core_exit);
459 
460 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
461 MODULE_DESCRIPTION("Core component of PowerMac thermal control");
462 MODULE_LICENSE("GPL");
463 
464