PM / Sleep: Add user space interface for manipulating wakeup sources, v3
[linux-2.6.git] / kernel / power / wakelock.c
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/ctype.h>
13 #include <linux/device.h>
14 #include <linux/err.h>
15 #include <linux/hrtimer.h>
16 #include <linux/list.h>
17 #include <linux/rbtree.h>
18 #include <linux/slab.h>
19
20 #define WL_NUMBER_LIMIT 100
21 #define WL_GC_COUNT_MAX 100
22 #define WL_GC_TIME_SEC  300
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         struct list_head        lru;
31 };
32
33 static struct rb_root wakelocks_tree = RB_ROOT;
34 static LIST_HEAD(wakelocks_lru_list);
35 static unsigned int number_of_wakelocks;
36 static unsigned int wakelocks_gc_count;
37
38 ssize_t pm_show_wakelocks(char *buf, bool show_active)
39 {
40         struct rb_node *node;
41         struct wakelock *wl;
42         char *str = buf;
43         char *end = buf + PAGE_SIZE;
44
45         mutex_lock(&wakelocks_lock);
46
47         for (node = rb_first(&wakelocks_tree); node; node = rb_next(node)) {
48                 wl = rb_entry(node, struct wakelock, node);
49                 if (wl->ws.active == show_active)
50                         str += scnprintf(str, end - str, "%s ", wl->name);
51         }
52         if (str > buf)
53                 str--;
54
55         str += scnprintf(str, end - str, "\n");
56
57         mutex_unlock(&wakelocks_lock);
58         return (str - buf);
59 }
60
61 static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
62                                             bool add_if_not_found)
63 {
64         struct rb_node **node = &wakelocks_tree.rb_node;
65         struct rb_node *parent = *node;
66         struct wakelock *wl;
67
68         while (*node) {
69                 int diff;
70
71                 parent = *node;
72                 wl = rb_entry(*node, struct wakelock, node);
73                 diff = strncmp(name, wl->name, len);
74                 if (diff == 0) {
75                         if (wl->name[len])
76                                 diff = -1;
77                         else
78                                 return wl;
79                 }
80                 if (diff < 0)
81                         node = &(*node)->rb_left;
82                 else
83                         node = &(*node)->rb_right;
84         }
85         if (!add_if_not_found)
86                 return ERR_PTR(-EINVAL);
87
88         if (number_of_wakelocks > WL_NUMBER_LIMIT)
89                 return ERR_PTR(-ENOSPC);
90
91         /* Not found, we have to add a new one. */
92         wl = kzalloc(sizeof(*wl), GFP_KERNEL);
93         if (!wl)
94                 return ERR_PTR(-ENOMEM);
95
96         wl->name = kstrndup(name, len, GFP_KERNEL);
97         if (!wl->name) {
98                 kfree(wl);
99                 return ERR_PTR(-ENOMEM);
100         }
101         wl->ws.name = wl->name;
102         wakeup_source_add(&wl->ws);
103         rb_link_node(&wl->node, parent, node);
104         rb_insert_color(&wl->node, &wakelocks_tree);
105         list_add(&wl->lru, &wakelocks_lru_list);
106         number_of_wakelocks++;
107         return wl;
108 }
109
110 int pm_wake_lock(const char *buf)
111 {
112         const char *str = buf;
113         struct wakelock *wl;
114         u64 timeout_ns = 0;
115         size_t len;
116         int ret = 0;
117
118         while (*str && !isspace(*str))
119                 str++;
120
121         len = str - buf;
122         if (!len)
123                 return -EINVAL;
124
125         if (*str && *str != '\n') {
126                 /* Find out if there's a valid timeout string appended. */
127                 ret = kstrtou64(skip_spaces(str), 10, &timeout_ns);
128                 if (ret)
129                         return -EINVAL;
130         }
131
132         mutex_lock(&wakelocks_lock);
133
134         wl = wakelock_lookup_add(buf, len, true);
135         if (IS_ERR(wl)) {
136                 ret = PTR_ERR(wl);
137                 goto out;
138         }
139         if (timeout_ns) {
140                 u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1;
141
142                 do_div(timeout_ms, NSEC_PER_MSEC);
143                 __pm_wakeup_event(&wl->ws, timeout_ms);
144         } else {
145                 __pm_stay_awake(&wl->ws);
146         }
147
148         list_move(&wl->lru, &wakelocks_lru_list);
149
150  out:
151         mutex_unlock(&wakelocks_lock);
152         return ret;
153 }
154
155 static void wakelocks_gc(void)
156 {
157         struct wakelock *wl, *aux;
158         ktime_t now = ktime_get();
159
160         list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) {
161                 u64 idle_time_ns;
162                 bool active;
163
164                 spin_lock_irq(&wl->ws.lock);
165                 idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws.last_time));
166                 active = wl->ws.active;
167                 spin_unlock_irq(&wl->ws.lock);
168
169                 if (idle_time_ns < ((u64)WL_GC_TIME_SEC * NSEC_PER_SEC))
170                         break;
171
172                 if (!active) {
173                         wakeup_source_remove(&wl->ws);
174                         rb_erase(&wl->node, &wakelocks_tree);
175                         list_del(&wl->lru);
176                         kfree(wl->name);
177                         kfree(wl);
178                         number_of_wakelocks--;
179                 }
180         }
181         wakelocks_gc_count = 0;
182 }
183
184 int pm_wake_unlock(const char *buf)
185 {
186         struct wakelock *wl;
187         size_t len;
188         int ret = 0;
189
190         len = strlen(buf);
191         if (!len)
192                 return -EINVAL;
193
194         if (buf[len-1] == '\n')
195                 len--;
196
197         if (!len)
198                 return -EINVAL;
199
200         mutex_lock(&wakelocks_lock);
201
202         wl = wakelock_lookup_add(buf, len, false);
203         if (IS_ERR(wl)) {
204                 ret = PTR_ERR(wl);
205                 goto out;
206         }
207         __pm_relax(&wl->ws);
208         list_move(&wl->lru, &wakelocks_lru_list);
209         if (++wakelocks_gc_count > WL_GC_COUNT_MAX)
210                 wakelocks_gc();
211
212  out:
213         mutex_unlock(&wakelocks_lock);
214         return ret;
215 }