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
21#include "power.h"
22
23static DEFINE_MUTEX(wakelocks_lock);
24
25struct wakelock {
26	char			*name;
27	struct rb_node		node;
28	struct wakeup_source	ws;
29#ifdef CONFIG_PM_WAKELOCKS_GC
30	struct list_head	lru;
31#endif
32};
33
34static struct rb_root wakelocks_tree = RB_ROOT;
35
36ssize_t pm_show_wakelocks(char *buf, bool show_active)
37{
38	struct rb_node *node;
39	struct wakelock *wl;
40	char *str = buf;
41	char *end = buf + PAGE_SIZE;
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			str += scnprintf(str, end - str, "%s ", wl->name);
49	}
50	if (str > buf)
51		str--;
52
53	str += scnprintf(str, end - str, "\n");
54
55	mutex_unlock(&wakelocks_lock);
56	return (str - buf);
57}
58
59#if CONFIG_PM_WAKELOCKS_LIMIT > 0
60static unsigned int number_of_wakelocks;
61
62static inline bool wakelocks_limit_exceeded(void)
63{
64	return number_of_wakelocks > CONFIG_PM_WAKELOCKS_LIMIT;
65}
66
67static inline void increment_wakelocks_number(void)
68{
69	number_of_wakelocks++;
70}
71
72static inline void decrement_wakelocks_number(void)
73{
74	number_of_wakelocks--;
75}
76#else /* CONFIG_PM_WAKELOCKS_LIMIT = 0 */
77static inline bool wakelocks_limit_exceeded(void) { return false; }
78static inline void increment_wakelocks_number(void) {}
79static inline void decrement_wakelocks_number(void) {}
80#endif /* CONFIG_PM_WAKELOCKS_LIMIT */
81
82#ifdef CONFIG_PM_WAKELOCKS_GC
83#define WL_GC_COUNT_MAX	100
84#define WL_GC_TIME_SEC	300
85
86static LIST_HEAD(wakelocks_lru_list);
87static unsigned int wakelocks_gc_count;
88
89static inline void wakelocks_lru_add(struct wakelock *wl)
90{
91	list_add(&wl->lru, &wakelocks_lru_list);
92}
93
94static inline void wakelocks_lru_most_recent(struct wakelock *wl)
95{
96	list_move(&wl->lru, &wakelocks_lru_list);
97}
98
99static void wakelocks_gc(void)
100{
101	struct wakelock *wl, *aux;
102	ktime_t now;
103
104	if (++wakelocks_gc_count <= WL_GC_COUNT_MAX)
105		return;
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_remove(&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#else /* !CONFIG_PM_WAKELOCKS_GC */
132static inline void wakelocks_lru_add(struct wakelock *wl) {}
133static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
134static inline void wakelocks_gc(void) {}
135#endif /* !CONFIG_PM_WAKELOCKS_GC */
136
137static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
138					    bool add_if_not_found)
139{
140	struct rb_node **node = &wakelocks_tree.rb_node;
141	struct rb_node *parent = *node;
142	struct wakelock *wl;
143
144	while (*node) {
145		int diff;
146
147		parent = *node;
148		wl = rb_entry(*node, struct wakelock, node);
149		diff = strncmp(name, wl->name, len);
150		if (diff == 0) {
151			if (wl->name[len])
152				diff = -1;
153			else
154				return wl;
155		}
156		if (diff < 0)
157			node = &(*node)->rb_left;
158		else
159			node = &(*node)->rb_right;
160	}
161	if (!add_if_not_found)
162		return ERR_PTR(-EINVAL);
163
164	if (wakelocks_limit_exceeded())
165		return ERR_PTR(-ENOSPC);
166
167	/* Not found, we have to add a new one. */
168	wl = kzalloc(sizeof(*wl), GFP_KERNEL);
169	if (!wl)
170		return ERR_PTR(-ENOMEM);
171
172	wl->name = kstrndup(name, len, GFP_KERNEL);
173	if (!wl->name) {
174		kfree(wl);
175		return ERR_PTR(-ENOMEM);
176	}
177	wl->ws.name = wl->name;
178	wakeup_source_add(&wl->ws);
179	rb_link_node(&wl->node, parent, node);
180	rb_insert_color(&wl->node, &wakelocks_tree);
181	wakelocks_lru_add(wl);
182	increment_wakelocks_number();
183	return wl;
184}
185
186int pm_wake_lock(const char *buf)
187{
188	const char *str = buf;
189	struct wakelock *wl;
190	u64 timeout_ns = 0;
191	size_t len;
192	int ret = 0;
193
194	if (!capable(CAP_BLOCK_SUSPEND))
195		return -EPERM;
196
197	while (*str && !isspace(*str))
198		str++;
199
200	len = str - buf;
201	if (!len)
202		return -EINVAL;
203
204	if (*str && *str != '\n') {
205		/* Find out if there's a valid timeout string appended. */
206		ret = kstrtou64(skip_spaces(str), 10, &timeout_ns);
207		if (ret)
208			return -EINVAL;
209	}
210
211	mutex_lock(&wakelocks_lock);
212
213	wl = wakelock_lookup_add(buf, len, true);
214	if (IS_ERR(wl)) {
215		ret = PTR_ERR(wl);
216		goto out;
217	}
218	if (timeout_ns) {
219		u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1;
220
221		do_div(timeout_ms, NSEC_PER_MSEC);
222		__pm_wakeup_event(&wl->ws, timeout_ms);
223	} else {
224		__pm_stay_awake(&wl->ws);
225	}
226
227	wakelocks_lru_most_recent(wl);
228
229 out:
230	mutex_unlock(&wakelocks_lock);
231	return ret;
232}
233
234int pm_wake_unlock(const char *buf)
235{
236	struct wakelock *wl;
237	size_t len;
238	int ret = 0;
239
240	if (!capable(CAP_BLOCK_SUSPEND))
241		return -EPERM;
242
243	len = strlen(buf);
244	if (!len)
245		return -EINVAL;
246
247	if (buf[len-1] == '\n')
248		len--;
249
250	if (!len)
251		return -EINVAL;
252
253	mutex_lock(&wakelocks_lock);
254
255	wl = wakelock_lookup_add(buf, len, false);
256	if (IS_ERR(wl)) {
257		ret = PTR_ERR(wl);
258		goto out;
259	}
260	__pm_relax(&wl->ws);
261
262	wakelocks_lru_most_recent(wl);
263	wakelocks_gc();
264
265 out:
266	mutex_unlock(&wakelocks_lock);
267	return ret;
268}
269