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
52static LIST_HEAD(wf_controls);
53static LIST_HEAD(wf_sensors);
54static DEFINE_MUTEX(wf_lock);
55static BLOCKING_NOTIFIER_HEAD(wf_client_list);
56static int wf_client_count;
57static unsigned int wf_overtemp;
58static unsigned int wf_overtemp_counter;
59struct task_struct *wf_thread;
60
61static struct platform_device wf_platform_device = {
62	.name	= "windfarm",
63};
64
65/*
66 * Utilities & tick thread
67 */
68
69static inline void wf_notify(int event, void *param)
70{
71	blocking_notifier_call_chain(&wf_client_list, event, param);
72}
73
74static 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
87static 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
127static 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
138static 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
149static 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
161static 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... */
189static 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
209int 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}
242EXPORT_SYMBOL_GPL(wf_register_control);
243
244void 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}
254EXPORT_SYMBOL_GPL(wf_unregister_control);
255
256int 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}
263EXPORT_SYMBOL_GPL(wf_get_control);
264
265void 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}
271EXPORT_SYMBOL_GPL(wf_put_control);
272
273
274/*
275 * Sensors
276 */
277
278
279static 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
291static 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
304int 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}
337EXPORT_SYMBOL_GPL(wf_register_sensor);
338
339void 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}
349EXPORT_SYMBOL_GPL(wf_unregister_sensor);
350
351int 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}
358EXPORT_SYMBOL_GPL(wf_get_sensor);
359
360void 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}
366EXPORT_SYMBOL_GPL(wf_put_sensor);
367
368
369/*
370 * Client & notification
371 */
372
373int 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}
394EXPORT_SYMBOL_GPL(wf_register_client);
395
396int 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}
407EXPORT_SYMBOL_GPL(wf_unregister_client);
408
409void 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}
420EXPORT_SYMBOL_GPL(wf_set_overtemp);
421
422void 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}
437EXPORT_SYMBOL_GPL(wf_clear_overtemp);
438
439static 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
447static 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
457module_init(windfarm_core_init);
458module_exit(windfarm_core_exit);
459
460MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
461MODULE_DESCRIPTION("Core component of PowerMac thermal control");
462MODULE_LICENSE("GPL");
463
464