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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 <[email protected]>
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 if (len > 0)
53 --len;
54
55 len += sysfs_emit_at(buf, len, "\n");
56
57 mutex_unlock(&wakelocks_lock);
58 return len;
59}
60
61#if CONFIG_PM_WAKELOCKS_LIMIT > 0
62static unsigned int number_of_wakelocks;
63
64static inline bool wakelocks_limit_exceeded(void)
65{
66 return number_of_wakelocks >= CONFIG_PM_WAKELOCKS_LIMIT;
67}
68
69static inline void increment_wakelocks_number(void)
70{
71 number_of_wakelocks++;
72}
73
74static inline void decrement_wakelocks_number(void)
75{
76 number_of_wakelocks--;
77}
78#else /* CONFIG_PM_WAKELOCKS_LIMIT = 0 */
79static inline bool wakelocks_limit_exceeded(void) { return false; }
80static inline void increment_wakelocks_number(void) {}
81static inline void decrement_wakelocks_number(void) {}
82#endif /* CONFIG_PM_WAKELOCKS_LIMIT */
83
84#ifdef CONFIG_PM_WAKELOCKS_GC
85#define WL_GC_COUNT_MAX 100
86#define WL_GC_TIME_SEC 300
87
88static void __wakelocks_gc(struct work_struct *work);
89static LIST_HEAD(wakelocks_lru_list);
90static DECLARE_WORK(wakelock_work, __wakelocks_gc);
91static unsigned int wakelocks_gc_count;
92
93static inline void wakelocks_lru_add(struct wakelock *wl)
94{
95 list_add(&wl->lru, &wakelocks_lru_list);
96}
97
98static inline void wakelocks_lru_most_recent(struct wakelock *wl)
99{
100 list_move(&wl->lru, &wakelocks_lru_list);
101}
102
103static void __wakelocks_gc(struct work_struct *work)
104{
105 struct wakelock *wl, *aux;
106 ktime_t now;
107
108 mutex_lock(&wakelocks_lock);
109
110 now = ktime_get();
111 list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) {
112 u64 idle_time_ns;
113 bool active;
114
115 spin_lock_irq(&wl->ws->lock);
116 idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws->last_time));
117 active = wl->ws->active;
118 spin_unlock_irq(&wl->ws->lock);
119
120 if (idle_time_ns < ((u64)WL_GC_TIME_SEC * NSEC_PER_SEC))
121 break;
122
123 if (!active) {
124 wakeup_source_unregister(wl->ws);
125 rb_erase(&wl->node, &wakelocks_tree);
126 list_del(&wl->lru);
127 kfree(wl->name);
128 kfree(wl);
129 decrement_wakelocks_number();
130 }
131 }
132 wakelocks_gc_count = 0;
133
134 mutex_unlock(&wakelocks_lock);
135}
136
137static void wakelocks_gc(void)
138{
139 if (++wakelocks_gc_count <= WL_GC_COUNT_MAX)
140 return;
141
142 schedule_work(&wakelock_work);
143}
144#else /* !CONFIG_PM_WAKELOCKS_GC */
145static inline void wakelocks_lru_add(struct wakelock *wl) {}
146static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
147static inline void wakelocks_gc(void) {}
148#endif /* !CONFIG_PM_WAKELOCKS_GC */
149
150static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
151 bool add_if_not_found)
152{
153 struct rb_node **node = &wakelocks_tree.rb_node;
154 struct rb_node *parent = *node;
155 struct wakelock *wl;
156
157 while (*node) {
158 int diff;
159
160 parent = *node;
161 wl = rb_entry(*node, struct wakelock, node);
162 diff = strncmp(name, wl->name, len);
163 if (diff == 0) {
164 if (wl->name[len])
165 diff = -1;
166 else
167 return wl;
168 }
169 if (diff < 0)
170 node = &(*node)->rb_left;
171 else
172 node = &(*node)->rb_right;
173 }
174 if (!add_if_not_found)
175 return ERR_PTR(-EINVAL);
176
177 if (wakelocks_limit_exceeded())
178 return ERR_PTR(-ENOSPC);
179
180 /* Not found, we have to add a new one. */
181 wl = kzalloc_obj(*wl);
182 if (!wl)
183 return ERR_PTR(-ENOMEM);
184
185 wl->name = kstrndup(name, len, GFP_KERNEL);
186 if (!wl->name) {
187 kfree(wl);
188 return ERR_PTR(-ENOMEM);
189 }
190
191 wl->ws = wakeup_source_register(NULL, wl->name);
192 if (!wl->ws) {
193 kfree(wl->name);
194 kfree(wl);
195 return ERR_PTR(-ENOMEM);
196 }
197 wl->ws->last_time = ktime_get();
198
199 rb_link_node(&wl->node, parent, node);
200 rb_insert_color(&wl->node, &wakelocks_tree);
201 wakelocks_lru_add(wl);
202 increment_wakelocks_number();
203 return wl;
204}
205
206int pm_wake_lock(const char *buf)
207{
208 const char *str = buf;
209 struct wakelock *wl;
210 u64 timeout_ns = 0;
211 size_t len;
212 int ret = 0;
213
214 if (!capable(CAP_BLOCK_SUSPEND))
215 return -EPERM;
216
217 while (*str && !isspace(*str))
218 str++;
219
220 len = str - buf;
221 if (!len)
222 return -EINVAL;
223
224 if (*str && *str != '\n') {
225 /* Find out if there's a valid timeout string appended. */
226 ret = kstrtou64(skip_spaces(str), 10, &timeout_ns);
227 if (ret)
228 return -EINVAL;
229 }
230
231 mutex_lock(&wakelocks_lock);
232
233 wl = wakelock_lookup_add(buf, len, true);
234 if (IS_ERR(wl)) {
235 ret = PTR_ERR(wl);
236 goto out;
237 }
238 if (timeout_ns) {
239 u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1;
240
241 do_div(timeout_ms, NSEC_PER_MSEC);
242 __pm_wakeup_event(wl->ws, timeout_ms);
243 } else {
244 __pm_stay_awake(wl->ws);
245 }
246
247 wakelocks_lru_most_recent(wl);
248
249 out:
250 mutex_unlock(&wakelocks_lock);
251 return ret;
252}
253
254int pm_wake_unlock(const char *buf)
255{
256 struct wakelock *wl;
257 size_t len;
258 int ret = 0;
259
260 if (!capable(CAP_BLOCK_SUSPEND))
261 return -EPERM;
262
263 len = strlen(buf);
264 if (!len)
265 return -EINVAL;
266
267 if (buf[len-1] == '\n')
268 len--;
269
270 if (!len)
271 return -EINVAL;
272
273 mutex_lock(&wakelocks_lock);
274
275 wl = wakelock_lookup_add(buf, len, false);
276 if (IS_ERR(wl)) {
277 ret = PTR_ERR(wl);
278 goto out;
279 }
280 __pm_relax(wl->ws);
281
282 wakelocks_lru_most_recent(wl);
283 wakelocks_gc();
284
285 out:
286 mutex_unlock(&wakelocks_lock);
287 return ret;
288}