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
wf_notify(int event,void * param)69 static inline void wf_notify(int event, void *param)
70 {
71 blocking_notifier_call_chain(&wf_client_list, event, param);
72 }
73
wf_critical_overtemp(void)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
wf_thread_func(void * data)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
wf_start_thread(void)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
wf_stop_thread(void)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
wf_control_release(struct kref * kref)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
wf_show_control(struct device * dev,struct device_attribute * attr,char * buf)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... */
wf_store_control(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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
wf_register_control(struct wf_control * new_ct)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
wf_unregister_control(struct wf_control * ct)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
wf_get_control(struct wf_control * ct)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
wf_put_control(struct wf_control * ct)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
wf_sensor_release(struct kref * kref)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
wf_show_sensor(struct device * dev,struct device_attribute * attr,char * buf)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
wf_register_sensor(struct wf_sensor * new_sr)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
wf_unregister_sensor(struct wf_sensor * sr)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
wf_get_sensor(struct wf_sensor * sr)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
wf_put_sensor(struct wf_sensor * sr)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
wf_register_client(struct notifier_block * nb)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
wf_unregister_client(struct notifier_block * nb)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
wf_set_overtemp(void)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
wf_clear_overtemp(void)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
windfarm_core_init(void)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
windfarm_core_exit(void)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