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
50static LIST_HEAD(wf_controls);
51static LIST_HEAD(wf_sensors);
52static DEFINE_MUTEX(wf_lock);
53static BLOCKING_NOTIFIER_HEAD(wf_client_list);
54static int wf_client_count;
55static unsigned int wf_overtemp;
56static unsigned int wf_overtemp_counter;
57static struct task_struct *wf_thread;
58
59static struct platform_device wf_platform_device = {
60	.name	= "windfarm",
61};
62
63/*
64 * Utilities & tick thread
65 */
66
67static inline void wf_notify(int event, void *param)
68{
69	blocking_notifier_call_chain(&wf_client_list, event, param);
70}
71
72static 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
85static 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
125static 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
136static 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
147static 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
159static 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... */
187static 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
207int 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}
240EXPORT_SYMBOL_GPL(wf_register_control);
241
242void 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}
252EXPORT_SYMBOL_GPL(wf_unregister_control);
253
254int 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}
261EXPORT_SYMBOL_GPL(wf_get_control);
262
263void 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}
269EXPORT_SYMBOL_GPL(wf_put_control);
270
271
272/*
273 * Sensors
274 */
275
276
277static 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
289static 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
302int 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}
335EXPORT_SYMBOL_GPL(wf_register_sensor);
336
337void 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}
347EXPORT_SYMBOL_GPL(wf_unregister_sensor);
348
349int 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}
356EXPORT_SYMBOL_GPL(wf_get_sensor);
357
358void 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}
364EXPORT_SYMBOL_GPL(wf_put_sensor);
365
366
367/*
368 * Client & notification
369 */
370
371int 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}
392EXPORT_SYMBOL_GPL(wf_register_client);
393
394int 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}
405EXPORT_SYMBOL_GPL(wf_unregister_client);
406
407void 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}
418EXPORT_SYMBOL_GPL(wf_set_overtemp);
419
420void 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}
435EXPORT_SYMBOL_GPL(wf_clear_overtemp);
436
437static 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
445static 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
455module_init(windfarm_core_init);
456module_exit(windfarm_core_exit);
457
458MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
459MODULE_DESCRIPTION("Core component of PowerMac thermal control");
460MODULE_LICENSE("GPL");
461
462