1// SPDX-License-Identifier: GPL-2.0
2/*
3 * kernel/power/wakelock.c
4 *
5 * User space wakeup sources support.
6 *
7 * Copyright (C) 2012 Rafael J. Wysocki <rjw@sisk.pl>
8 *
9 * This code is based on the analogous interface allowing user space to
10 * manipulate wakelocks on Android.
11 */
12
13#include <linux/capability.h>
14#include <linux/ctype.h>
15#include <linux/device.h>
16#include <linux/err.h>
17#include <linux/hrtimer.h>
18#include <linux/list.h>
19#include <linux/rbtree.h>
20#include <linux/slab.h>
21#include <linux/workqueue.h>
22
23#include "power.h"
24
25static DEFINE_MUTEX(wakelocks_lock);
26
27struct wakelock {
28	char			*name;
29	struct rb_node		node;
30	struct wakeup_source	*ws;
31#ifdef CONFIG_PM_WAKELOCKS_GC
32	struct list_head	lru;
33#endif
34};
35
36static struct rb_root wakelocks_tree = RB_ROOT;
37
38ssize_t pm_show_wakelocks(char *buf, bool show_active)
39{
40	struct rb_node *node;
41	struct wakelock *wl;
42	int len = 0;
43
44	mutex_lock(&wakelocks_lock);
45
46	for (node = rb_first(&wakelocks_tree); node; node = rb_next(node)) {
47		wl = rb_entry(node, struct wakelock, node);
48		if (wl->ws->active == show_active)
49			len += sysfs_emit_at(buf, len, "%s ", wl->name);
50	}
51
52	len += sysfs_emit_at(buf, len, "\n");
53
54	mutex_unlock(&wakelocks_lock);
55	return len;
56}
57
58#if CONFIG_PM_WAKELOCKS_LIMIT > 0
59static unsigned int number_of_wakelocks;
60
61static inline bool wakelocks_limit_exceeded(void)
62{
63	return number_of_wakelocks > CONFIG_PM_WAKELOCKS_LIMIT;
64}
65
66static inline void increment_wakelocks_number(void)
67{
68	number_of_wakelocks++;
69}
70
71static inline void decrement_wakelocks_number(void)
72{
73	number_of_wakelocks--;
74}
75#else /* CONFIG_PM_WAKELOCKS_LIMIT = 0 */
76static inline bool wakelocks_limit_exceeded(void) { return false; }
77static inline void increment_wakelocks_number(void) {}
78static inline void decrement_wakelocks_number(void) {}
79#endif /* CONFIG_PM_WAKELOCKS_LIMIT */
80
81#ifdef CONFIG_PM_WAKELOCKS_GC
82#define WL_GC_COUNT_MAX	100
83#define WL_GC_TIME_SEC	300
84
85static void __wakelocks_gc(struct work_struct *work);
86static LIST_HEAD(wakelocks_lru_list);
87static DECLARE_WORK(wakelock_work, __wakelocks_gc);
88static unsigned int wakelocks_gc_count;
89
90static inline void wakelocks_lru_add(struct wakelock *wl)
91{
92	list_add(&wl->lru, &wakelocks_lru_list);
93}
94
95static inline void wakelocks_lru_most_recent(struct wakelock *wl)
96{
97	list_move(&wl->lru, &wakelocks_lru_list);
98}
99
100static void __wakelocks_gc(struct work_struct *work)
101{
102	struct wakelock *wl, *aux;
103	ktime_t now;
104
105	mutex_lock(&wakelocks_lock);
106
107	now = ktime_get();
108	list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) {
109		u64 idle_time_ns;
110		bool active;
111
112		spin_lock_irq(&wl->ws->lock);
113		idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws->last_time));
114		active = wl->ws->active;
115		spin_unlock_irq(&wl->ws->lock);
116
117		if (idle_time_ns < ((u64)WL_GC_TIME_SEC * NSEC_PER_SEC))
118			break;
119
120		if (!active) {
121			wakeup_source_unregister(wl->ws);
122			rb_erase(&wl->node, &wakelocks_tree);
123			list_del(&wl->lru);
124			kfree(wl->name);
125			kfree(wl);
126			decrement_wakelocks_number();
127		}
128	}
129	wakelocks_gc_count = 0;
130
131	mutex_unlock(&wakelocks_lock);
132}
133
134static void wakelocks_gc(void)
135{
136	if (++wakelocks_gc_count <= WL_GC_COUNT_MAX)
137		return;
138
139	schedule_work(&wakelock_work);
140}
141#else /* !CONFIG_PM_WAKELOCKS_GC */
142static inline void wakelocks_lru_add(struct wakelock *wl) {}
143static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
144static inline void wakelocks_gc(void) {}
145#endif /* !CONFIG_PM_WAKELOCKS_GC */
146
147static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
148					    bool add_if_not_found)
149{
150	struct rb_node **node = &wakelocks_tree.rb_node;
151	struct rb_node *parent = *node;
152	struct wakelock *wl;
153
154	while (*node) {
155		int diff;
156
157		parent = *node;
158		wl = rb_entry(*node, struct wakelock, node);
159		diff = strncmp(name, wl->name, len);
160		if (diff == 0) {
161			if (wl->name[len])
162				diff = -1;
163			else
164				return wl;
165		}
166		if (diff < 0)
167			node = &(*node)->rb_left;
168		else
169			node = &(*node)->rb_right;
170	}
171	if (!add_if_not_found)
172		return ERR_PTR(-EINVAL);
173
174	if (wakelocks_limit_exceeded())
175		return ERR_PTR(-ENOSPC);
176
177	/* Not found, we have to add a new one. */
178	wl = kzalloc(sizeof(*wl), GFP_KERNEL);
179	if (!wl)
180		return ERR_PTR(-ENOMEM);
181
182	wl->name = kstrndup(name, len, GFP_KERNEL);
183	if (!wl->name) {
184		kfree(wl);
185		return ERR_PTR(-ENOMEM);
186	}
187
188	wl->ws = wakeup_source_register(NULL, wl->name);
189	if (!wl->ws) {
190		kfree(wl->name);
191		kfree(wl);
192		return ERR_PTR(-ENOMEM);
193	}
194	wl->ws->last_time = ktime_get();
195
196	rb_link_node(&wl->node, parent, node);
197	rb_insert_color(&wl->node, &wakelocks_tree);
198	wakelocks_lru_add(wl);
199	increment_wakelocks_number();
200	return wl;
201}
202
203int pm_wake_lock(const char *buf)
204{
205	const char *str = buf;
206	struct wakelock *wl;
207	u64 timeout_ns = 0;
208	size_t len;
209	int ret = 0;
210
211	if (!capable(CAP_BLOCK_SUSPEND))
212		return -EPERM;
213
214	while (*str && !isspace(*str))
215		str++;
216
217	len = str - buf;
218	if (!len)
219		return -EINVAL;
220
221	if (*str && *str != '\n') {
222		/* Find out if there's a valid timeout string appended. */
223		ret = kstrtou64(skip_spaces(str), 10, &timeout_ns);
224		if (ret)
225			return -EINVAL;
226	}
227
228	mutex_lock(&wakelocks_lock);
229
230	wl = wakelock_lookup_add(buf, len, true);
231	if (IS_ERR(wl)) {
232		ret = PTR_ERR(wl);
233		goto out;
234	}
235	if (timeout_ns) {
236		u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1;
237
238		do_div(timeout_ms, NSEC_PER_MSEC);
239		__pm_wakeup_event(wl->ws, timeout_ms);
240	} else {
241		__pm_stay_awake(wl->ws);
242	}
243
244	wakelocks_lru_most_recent(wl);
245
246 out:
247	mutex_unlock(&wakelocks_lock);
248	return ret;
249}
250
251int pm_wake_unlock(const char *buf)
252{
253	struct wakelock *wl;
254	size_t len;
255	int ret = 0;
256
257	if (!capable(CAP_BLOCK_SUSPEND))
258		return -EPERM;
259
260	len = strlen(buf);
261	if (!len)
262		return -EINVAL;
263
264	if (buf[len-1] == '\n')
265		len--;
266
267	if (!len)
268		return -EINVAL;
269
270	mutex_lock(&wakelocks_lock);
271
272	wl = wakelock_lookup_add(buf, len, false);
273	if (IS_ERR(wl)) {
274		ret = PTR_ERR(wl);
275		goto out;
276	}
277	__pm_relax(wl->ws);
278
279	wakelocks_lru_most_recent(wl);
280	wakelocks_gc();
281
282 out:
283	mutex_unlock(&wakelocks_lock);
284	return ret;
285}
286