From b86ff9820fd5df69295273b9aa68e58786ffc23f Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sun, 29 Apr 2012 22:53:42 +0200 Subject: PM / Sleep: Add user space interface for manipulating wakeup sources, v3 Android allows user space to manipulate wakelocks using two sysfs file located in /sys/power/, wake_lock and wake_unlock. Writing a wakelock name and optionally a timeout to the wake_lock file causes the wakelock whose name was written to be acquired (it is created before is necessary), optionally with the given timeout. Writing the name of a wakelock to wake_unlock causes that wakelock to be released. Implement an analogous interface for user space using wakeup sources. Add the /sys/power/wake_lock and /sys/power/wake_unlock files allowing user space to create, activate and deactivate wakeup sources, such that writing a name and optionally a timeout to wake_lock causes the wakeup source of that name to be activated, optionally with the given timeout. If that wakeup source doesn't exist, it will be created and then activated. Writing a name to wake_unlock causes the wakeup source of that name, if there is one, to be deactivated. Wakeup sources created with the help of wake_lock that haven't been used for more than 5 minutes are garbage collected and destroyed. Moreover, there can be only WL_NUMBER_LIMIT wakeup sources created with the help of wake_lock present at a time. The data type used to track wakeup sources created by user space is called "struct wakelock" to indicate the origins of this feature. This version of the patch includes an rbtree manipulation fix from John Stultz. Signed-off-by: Rafael J. Wysocki Acked-by: Greg Kroah-Hartman Reviewed-by: NeilBrown --- kernel/power/wakelock.c | 215 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 215 insertions(+) create mode 100644 kernel/power/wakelock.c (limited to 'kernel/power/wakelock.c') diff --git a/kernel/power/wakelock.c b/kernel/power/wakelock.c new file mode 100644 index 00000000000..579700665e8 --- /dev/null +++ b/kernel/power/wakelock.c @@ -0,0 +1,215 @@ +/* + * kernel/power/wakelock.c + * + * User space wakeup sources support. + * + * Copyright (C) 2012 Rafael J. Wysocki + * + * This code is based on the analogous interface allowing user space to + * manipulate wakelocks on Android. + */ + +#include +#include +#include +#include +#include +#include +#include + +#define WL_NUMBER_LIMIT 100 +#define WL_GC_COUNT_MAX 100 +#define WL_GC_TIME_SEC 300 + +static DEFINE_MUTEX(wakelocks_lock); + +struct wakelock { + char *name; + struct rb_node node; + struct wakeup_source ws; + struct list_head lru; +}; + +static struct rb_root wakelocks_tree = RB_ROOT; +static LIST_HEAD(wakelocks_lru_list); +static unsigned int number_of_wakelocks; +static unsigned int wakelocks_gc_count; + +ssize_t pm_show_wakelocks(char *buf, bool show_active) +{ + struct rb_node *node; + struct wakelock *wl; + char *str = buf; + char *end = buf + PAGE_SIZE; + + mutex_lock(&wakelocks_lock); + + for (node = rb_first(&wakelocks_tree); node; node = rb_next(node)) { + wl = rb_entry(node, struct wakelock, node); + if (wl->ws.active == show_active) + str += scnprintf(str, end - str, "%s ", wl->name); + } + if (str > buf) + str--; + + str += scnprintf(str, end - str, "\n"); + + mutex_unlock(&wakelocks_lock); + return (str - buf); +} + +static struct wakelock *wakelock_lookup_add(const char *name, size_t len, + bool add_if_not_found) +{ + struct rb_node **node = &wakelocks_tree.rb_node; + struct rb_node *parent = *node; + struct wakelock *wl; + + while (*node) { + int diff; + + parent = *node; + wl = rb_entry(*node, struct wakelock, node); + diff = strncmp(name, wl->name, len); + if (diff == 0) { + if (wl->name[len]) + diff = -1; + else + return wl; + } + if (diff < 0) + node = &(*node)->rb_left; + else + node = &(*node)->rb_right; + } + if (!add_if_not_found) + return ERR_PTR(-EINVAL); + + if (number_of_wakelocks > WL_NUMBER_LIMIT) + return ERR_PTR(-ENOSPC); + + /* Not found, we have to add a new one. */ + wl = kzalloc(sizeof(*wl), GFP_KERNEL); + if (!wl) + return ERR_PTR(-ENOMEM); + + wl->name = kstrndup(name, len, GFP_KERNEL); + if (!wl->name) { + kfree(wl); + return ERR_PTR(-ENOMEM); + } + wl->ws.name = wl->name; + wakeup_source_add(&wl->ws); + rb_link_node(&wl->node, parent, node); + rb_insert_color(&wl->node, &wakelocks_tree); + list_add(&wl->lru, &wakelocks_lru_list); + number_of_wakelocks++; + return wl; +} + +int pm_wake_lock(const char *buf) +{ + const char *str = buf; + struct wakelock *wl; + u64 timeout_ns = 0; + size_t len; + int ret = 0; + + while (*str && !isspace(*str)) + str++; + + len = str - buf; + if (!len) + return -EINVAL; + + if (*str && *str != '\n') { + /* Find out if there's a valid timeout string appended. */ + ret = kstrtou64(skip_spaces(str), 10, &timeout_ns); + if (ret) + return -EINVAL; + } + + mutex_lock(&wakelocks_lock); + + wl = wakelock_lookup_add(buf, len, true); + if (IS_ERR(wl)) { + ret = PTR_ERR(wl); + goto out; + } + if (timeout_ns) { + u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1; + + do_div(timeout_ms, NSEC_PER_MSEC); + __pm_wakeup_event(&wl->ws, timeout_ms); + } else { + __pm_stay_awake(&wl->ws); + } + + list_move(&wl->lru, &wakelocks_lru_list); + + out: + mutex_unlock(&wakelocks_lock); + return ret; +} + +static void wakelocks_gc(void) +{ + struct wakelock *wl, *aux; + ktime_t now = ktime_get(); + + list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) { + u64 idle_time_ns; + bool active; + + spin_lock_irq(&wl->ws.lock); + idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws.last_time)); + active = wl->ws.active; + spin_unlock_irq(&wl->ws.lock); + + if (idle_time_ns < ((u64)WL_GC_TIME_SEC * NSEC_PER_SEC)) + break; + + if (!active) { + wakeup_source_remove(&wl->ws); + rb_erase(&wl->node, &wakelocks_tree); + list_del(&wl->lru); + kfree(wl->name); + kfree(wl); + number_of_wakelocks--; + } + } + wakelocks_gc_count = 0; +} + +int pm_wake_unlock(const char *buf) +{ + struct wakelock *wl; + size_t len; + int ret = 0; + + len = strlen(buf); + if (!len) + return -EINVAL; + + if (buf[len-1] == '\n') + len--; + + if (!len) + return -EINVAL; + + mutex_lock(&wakelocks_lock); + + wl = wakelock_lookup_add(buf, len, false); + if (IS_ERR(wl)) { + ret = PTR_ERR(wl); + goto out; + } + __pm_relax(&wl->ws); + list_move(&wl->lru, &wakelocks_lru_list); + if (++wakelocks_gc_count > WL_GC_COUNT_MAX) + wakelocks_gc(); + + out: + mutex_unlock(&wakelocks_lock); + return ret; +} -- cgit v1.2.3-70-g09d2