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