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
wf_notify(int event,void * param)67 static inline void wf_notify(int event, void *param)
68 {
69 blocking_notifier_call_chain(&wf_client_list, event, param);
70 }
71
wf_critical_overtemp(void)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
wf_thread_func(void * data)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
wf_start_thread(void)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
wf_stop_thread(void)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
wf_control_release(struct kref * kref)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
wf_show_control(struct device * dev,struct device_attribute * attr,char * buf)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... */
wf_store_control(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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
wf_register_control(struct wf_control * new_ct)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
wf_unregister_control(struct wf_control * ct)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
wf_get_control(struct wf_control * ct)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
wf_put_control(struct wf_control * ct)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
wf_sensor_release(struct kref * kref)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
wf_show_sensor(struct device * dev,struct device_attribute * attr,char * buf)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
wf_register_sensor(struct wf_sensor * new_sr)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
wf_unregister_sensor(struct wf_sensor * sr)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
wf_get_sensor(struct wf_sensor * sr)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
wf_put_sensor(struct wf_sensor * sr)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
wf_register_client(struct notifier_block * nb)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
wf_unregister_client(struct notifier_block * nb)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
wf_set_overtemp(void)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
wf_clear_overtemp(void)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
windfarm_core_init(void)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
windfarm_core_exit(void)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