Adds /sys/power/request_state, a non-blocking interface that specifieswhich suspend state to enter when no suspend blockers are active. Aspecial state, "on", stops the process by activating the "main" suspendblocker.
Signed-off-by: Arve Hjønnevåg <arve@xxxxxxxxxxx>--- Documentation/power/suspend-blockers.txt | 94 +++++++++++++ include/linux/suspend_blocker.h | 60 +++++++++ kernel/power/Kconfig | 10 ++ kernel/power/Makefile | 1 + kernel/power/main.c | 62 +++++++++- kernel/power/power.h | 4 + kernel/power/suspend_blocker.c | 209 ++++++++++++++++++++++++++++++ 7 files changed, 439 insertions(+), 1 deletions(-) create mode 100644 Documentation/power/suspend-blockers.txt create mode 100755 include/linux/suspend_blocker.h create mode 100644 kernel/power/suspend_blocker.c
diff --git a/Documentation/power/suspend-blockers.txt b/Documentation/power/suspend-blockers.txtnew file mode 100644index 0000000..5a33ed6--- /dev/null+++ b/Documentation/power/suspend-blockers.txt@@ -0,0 +1,94 @@+Suspend blockers+================++Suspend blockers provide a mechanism for device drivers and user-space processes+to prevent the system from entering suspend. Only suspend states requested+through /sys/power/request_state are prevented. Writing to /sys/power/state+will ignore suspend blockers, and sleep states entered from idle are unaffected.++To use a suspend blocker, a device driver needs a struct suspend_blocker object+that has to be initialized with suspend_blocker_init. When no longer needed,+the suspend blocker must be destroyed with suspend_blocker_destroy.++A suspend blocker is activated using suspend_block, which prevents the system+from entering suspend until the suspend blocker is deactivated with+suspend_unblock. Many suspend blockers may be used simultaneously, and the+system is prevented from entering suspend as long as at least one of them is+active.++If the suspend operation has already started when calling suspend_block on a+suspend_blocker, it will abort the suspend operation as long it has not already+reached called suspend_ops->enter. This means that calling suspend_block from an+interrupt handler or a freezeable thread always works, but some or all drivers+may be temporarily suspended.++In cell phones or other embedded systems where powering the screen is a+significant drain on the battery, suspend blockers can be used to allow+user-space to decide whether a keystroke received while the system is suspended+should cause the screen to be turned back on or allow the system to go back into+suspend. Use set_irq_wake or a platform specific api to make sure the keypad+interrupt wakes up the cpu. Once the keypad driver has resumed, the sequence of+events can look like this:++- The Keypad driver gets an interrupt. It then calls suspend_block on the+ keypad-scan suspend_blocker and starts scanning the keypad matrix.+- The keypad-scan code detects a key change and reports it to the input-event+ driver.+- The input-event driver sees the key change, enqueues an event, and calls+ suspend_block on the input-event-queue suspend_blocker.+- The keypad-scan code detects that no keys are held and calls suspend_unblock+ on the keypad-scan suspend_blocker.+- The user-space input-event thread returns from select/poll, calls+ suspend_block on the process-input-events suspend_blocker and then calls read+ on the input-event device.+- The input-event driver dequeues the key-event and, since the queue is now+ empty, it calls suspend_unblock on the input-event-queue suspend_blocker.+- The user-space input-event thread returns from read. If it determines that+ the key should leave the screen off, it calls suspend_unblock on the+ process_input_events suspend_blocker and then calls select or poll. The+ system will automatically suspend again, since now no suspend blockers are+ active.++ Key pressed Key released+ | |+keypad-scan +++++++++++++++++++input-event-queue +++ ++++process-input-events +++ ++++++Driver API+==========++A driver can use the suspend block api by adding a suspend_blocker variable to+its state and calling suspend_blocker_init. For instance:+struct state {+ struct suspend_blocker suspend_blocker;+}++init() {+ suspend_blocker_init(&state->suspend_blocker, "suspend-blocker-name");+}++Before freeing the memory, suspend_blocker_destroy must be called:++uninit() {+ suspend_blocker_destroy(&state->suspend_blocker);+}++When the driver determines that it needs to run (usually in an interrupt+handler) it calls suspend_block:+ suspend_block(&state->suspend_blocker);++When it no longer needs to run it calls suspend_unblock:+ suspend_unblock(&state->suspend_blocker);++Calling suspend_block when the suspend blocker is active or suspend_unblock when+it is not active has no effect. This allows drivers to update their state and+call suspend suspend_block or suspend_unblock based on the result.+For instance:++if (list_empty(&state->pending_work))+ suspend_unblock(&state->suspend_blocker);+else+ suspend_block(&state->suspend_blocker);+diff --git a/include/linux/suspend_blocker.h b/include/linux/suspend_blocker.hnew file mode 100755index 0000000..21689cd--- /dev/null+++ b/include/linux/suspend_blocker.h@@ -0,0 +1,60 @@+/* include/linux/suspend_blocker.h+ *+ * Copyright (C) 2007-2009 Google, Inc.+ *+ * This software is licensed under the terms of the GNU General Public+ * License version 2, as published by the Free Software Foundation, and+ * may be copied, distributed, and modified under those terms.+ *+ * This program is distributed in the hope that it will be useful,+ * but WITHOUT ANY WARRANTY; without even the implied warranty of+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the+ * GNU General Public License for more details.+ *+ */++#ifndef _LINUX_SUSPEND_BLOCKER_H+#define _LINUX_SUSPEND_BLOCKER_H++/**+ * struct suspend_blocker - the basic suspend_blocker structure+ * @flags: Tracks initialized and active state.+ * @name: Name used for debugging.+ *+ * When a suspend_blocker is active it prevents the system from entering+ * suspend.+ *+ * The suspend_blocker structure must be initialized by suspend_blocker_init()+ */++struct suspend_blocker {+#ifdef CONFIG_SUSPEND_BLOCKERS+ atomic_t flags;+ const char *name;+#endif+};++#ifdef CONFIG_SUSPEND_BLOCKERS++void suspend_blocker_init(struct suspend_blocker *blocker, const char *name);+void suspend_blocker_destroy(struct suspend_blocker *blocker);+void suspend_block(struct suspend_blocker *blocker);+void suspend_unblock(struct suspend_blocker *blocker);+bool suspend_blocker_is_active(struct suspend_blocker *blocker);+bool suspend_is_blocked(void);++#else++static inline void suspend_blocker_init(struct suspend_blocker *blocker,+ const char *name) {}+static inline void suspend_blocker_destroy(struct suspend_blocker *blocker) {}+static inline void suspend_block(struct suspend_blocker *blocker) {}+static inline void suspend_unblock(struct suspend_blocker *blocker) {}+static inline bool suspend_blocker_is_active(struct suspend_blocker *bl)+ { return 0; }+static inline bool suspend_is_blocked(void) { return 0; }++#endif++#endif+diff --git a/kernel/power/Kconfig b/kernel/power/Kconfigindex 23bd4da..a3587d3 100644--- a/kernel/power/Kconfig+++ b/kernel/power/Kconfig@@ -116,6 +116,16 @@ config SUSPEND_FREEZER Turning OFF this setting is NOT recommended! If in doubt, say Y. +config SUSPEND_BLOCKERS+ bool "Suspend blockers"+ depends on PM+ select RTC_LIB+ default n+ ---help---+ Enable suspend blockers. When user space requests a sleep state+ through /sys/power/request_state, the requested sleep state will be+ entered when no suspend blockers are active.+ config HIBERNATION bool "Hibernation (aka 'suspend to disk')" depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLEdiff --git a/kernel/power/Makefile b/kernel/power/Makefileindex 720ea4f..e8c7f85 100644--- a/kernel/power/Makefile+++ b/kernel/power/Makefile@@ -6,6 +6,7 @@ endif obj-$(CONFIG_PM) += main.o obj-$(CONFIG_PM_SLEEP) += console.o obj-$(CONFIG_FREEZER) += process.o+obj-$(CONFIG_SUSPEND_BLOCKERS) += suspend_blocker.o obj-$(CONFIG_HIBERNATION) += swsusp.o disk.o snapshot.o swap.o user.o obj-$(CONFIG_MAGIC_SYSRQ) += poweroff.odiff --git a/kernel/power/main.c b/kernel/power/main.cindex f99ed6a..1899cda 100644--- a/kernel/power/main.c+++ b/kernel/power/main.c@@ -22,6 +22,7 @@ #include <linux/freezer.h> #include <linux/vmstat.h> #include <linux/syscalls.h>+#include <linux/suspend_blocker.h> #include "power.h" @@ -321,7 +322,7 @@ static int suspend_enter(suspend_state_t state) error = sysdev_suspend(PMSG_SUSPEND); if (!error) {- if (!suspend_test(TEST_CORE))+ if (!suspend_is_blocked() && !suspend_test(TEST_CORE)) error = suspend_ops->enter(state); sysdev_resume(); }@@ -413,6 +414,7 @@ static void suspend_finish(void) static const char * const pm_states[PM_SUSPEND_MAX] = {+ [PM_SUSPEND_ON] = "on", [PM_SUSPEND_STANDBY] = "standby", [PM_SUSPEND_MEM] = "mem", };@@ -561,6 +563,61 @@ static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr, power_attr(state); +/**+ * request_state - control system power state.+ *+ * This is similar to state, but it does not block until the system+ * resumes, and it will try to re-enter the state until another state is+ * requested. Suspend blockers are respected and the requested state will+ * only be entered when no suspend blockers are active.+ * Write "on" to cancel.+ */++#ifdef CONFIG_SUSPEND_BLOCKERS+static ssize_t request_state_show(struct kobject *kobj,+ struct kobj_attribute *attr, char *buf)+{+ char *s = buf;+ int i;++ for (i = 0; i < PM_SUSPEND_MAX; i++) {+ if (pm_states[i] && (i == PM_SUSPEND_ON || valid_state(i)))+ s += sprintf(s, "%s ", pm_states[i]);+ }+ if (s != buf)+ /* convert the last space to a newline */+ *(s-1) = '\n';+ return (s - buf);+}++static ssize_t request_state_store(struct kobject *kobj,+ struct kobj_attribute *attr,+ const char *buf, size_t n)+{+ suspend_state_t state = PM_SUSPEND_ON;+ const char * const *s;+ char *p;+ int len;+ int error = -EINVAL;++ p = memchr(buf, '\n', n);+ len = p ? p - buf : n;++ for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {+ if (*s && len == strlen(*s) && !strncmp(buf, *s, len))+ break;+ }+ if (state < PM_SUSPEND_MAX && *s)+ if (state == PM_SUSPEND_ON || valid_state(state)) {+ error = 0;+ request_suspend_state(state);+ }+ return error ? error : n;+}++power_attr(request_state);+#endif /* CONFIG_SUSPEND_BLOCKERS */+ #ifdef CONFIG_PM_TRACE int pm_trace_enabled; @@ -588,6 +645,9 @@ power_attr(pm_trace); static struct attribute * g[] = { &state_attr.attr,+#ifdef CONFIG_SUSPEND_BLOCKERS+ &request_state_attr.attr,+#endif #ifdef CONFIG_PM_TRACE &pm_trace_attr.attr, #endifdiff --git a/kernel/power/power.h b/kernel/power/power.hindex 46b5ec7..2246b3b 100644--- a/kernel/power/power.h+++ b/kernel/power/power.h@@ -223,3 +223,7 @@ static inline void suspend_thaw_processes(void) { } #endif++/* kernel/power/suspend_block.c */+void request_suspend_state(suspend_state_t state);+diff --git a/kernel/power/suspend_blocker.c b/kernel/power/suspend_blocker.cnew file mode 100644index 0000000..6b9ca2d--- /dev/null+++ b/kernel/power/suspend_blocker.c@@ -0,0 +1,209 @@+/* kernel/power/suspend_blocker.c+ *+ * Copyright (C) 2005-2008 Google, Inc.+ *+ * This software is licensed under the terms of the GNU General Public+ * License version 2, as published by the Free Software Foundation, and+ * may be copied, distributed, and modified under those terms.+ *+ * This program is distributed in the hope that it will be useful,+ * but WITHOUT ANY WARRANTY; without even the implied warranty of+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the+ * GNU General Public License for more details.+ *+ */++#include <linux/module.h>+#include <linux/rtc.h>+#include <linux/suspend.h>+#include <linux/suspend_blocker.h>+#include "power.h"++enum {+ DEBUG_EXIT_SUSPEND = 1U << 0,+ DEBUG_WAKEUP = 1U << 1,+ DEBUG_USER_STATE = 1U << 2,+ DEBUG_SUSPEND = 1U << 3,+ DEBUG_SUSPEND_BLOCKER = 1U << 4,+};+static int debug_mask = DEBUG_EXIT_SUSPEND | DEBUG_WAKEUP | DEBUG_USER_STATE;+module_param_named(debug_mask, debug_mask, int, S_IRUGO | S_IWUSR | S_IWGRP);++#define SB_INITIALIZED (1U << 8)+#define SB_ACTIVE (1U << 9)++static DEFINE_SPINLOCK(state_lock);+static atomic_t suspend_block_count;+static atomic_t current_event_num;+struct workqueue_struct *suspend_work_queue;+struct suspend_blocker main_suspend_blocker;+static suspend_state_t requested_suspend_state = PM_SUSPEND_MEM;+static bool enable_suspend_blockers;++#define pr_info_time(fmt, args...) \+ do { \+ struct timespec ts; \+ struct rtc_time tm; \+ getnstimeofday(&ts); \+ rtc_time_to_tm(ts.tv_sec, &tm); \+ pr_info(fmt "(%d-%02d-%02d %02d:%02d:%02d.%09lu UTC)\n" , \+ args, \+ tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, \+ tm.tm_hour, tm.tm_min, tm.tm_sec, ts.tv_nsec); \+ } while (0);++/**+ * suspend_is_blocked() - Check if suspend should be blocked+ *+ * suspend_is_blocked can be used by generic power management code to abort+ * suspend.+ *+ * To preserve backward compatibility suspend_is_blocked returns 0 unless it+ * is called during suspend initiated from the suspend_block code.+ */+bool suspend_is_blocked(void)+{+ if (!enable_suspend_blockers)+ return 0;+ return !!atomic_read(&suspend_block_count);+}++static void suspend_worker(struct work_struct *work)+{+ int ret;+ int entry_event_num;++ enable_suspend_blockers = true;+ while (!suspend_is_blocked()) {+ entry_event_num = atomic_read(¤t_event_num);+ if (debug_mask & DEBUG_SUSPEND)+ pr_info("suspend: enter suspend\n");+ ret = pm_suspend(requested_suspend_state);+ if (debug_mask & DEBUG_EXIT_SUSPEND)+ pr_info_time("suspend: exit suspend, ret = %d ", ret);+ if (atomic_read(¤t_event_num) == entry_event_num)+ pr_info("suspend: pm_suspend returned with no event\n");+ }+ enable_suspend_blockers = false;+}+static DECLARE_WORK(suspend_work, suspend_worker);++/**+ * suspend_blocker_init() - Initialize a suspend blocker+ * @blocker: The suspend blocker to initialize.+ * @name: The name of the suspend blocker to show in debug messages.+ *+ * The suspend blocker struct and name must not be freed before calling+ * suspend_blocker_destroy.+ */+void suspend_blocker_init(struct suspend_blocker *blocker, const char *name)+{+ WARN_ON(!name);++ if (debug_mask & DEBUG_SUSPEND_BLOCKER)+ pr_info("suspend_blocker_init name=%s\n", name);++ blocker->name = name;+ atomic_set(&blocker->flags, SB_INITIALIZED);+}+EXPORT_SYMBOL(suspend_blocker_init);++/**+ * suspend_blocker_destroy() - Destroy a suspend blocker+ * @blocker: The suspend blocker to destroy.+ */+void suspend_blocker_destroy(struct suspend_blocker *blocker)+{+ int flags;+ if (debug_mask & DEBUG_SUSPEND_BLOCKER)+ pr_info("suspend_blocker_destroy name=%s\n", blocker->name);+ flags = atomic_xchg(&blocker->flags, 0);+ WARN(!(flags & SB_INITIALIZED), "suspend_blocker_destroy called on "+ "uninitialized suspend_blocker\n");+ if (flags == (SB_INITIALIZED | SB_ACTIVE))+ if (atomic_dec_and_test(&suspend_block_count))+ queue_work(suspend_work_queue, &suspend_work);+}+EXPORT_SYMBOL(suspend_blocker_destroy);++/**+ * suspend_block() - Block suspend+ * @blocker: The suspend blocker to use+ */+void suspend_block(struct suspend_blocker *blocker)+{+ WARN_ON(!(atomic_read(&blocker->flags) & SB_INITIALIZED));++ if (debug_mask & DEBUG_SUSPEND_BLOCKER)+ pr_info("suspend_block: %s\n", blocker->name);+ if (atomic_cmpxchg(&blocker->flags, SB_INITIALIZED,+ SB_INITIALIZED | SB_ACTIVE) == SB_INITIALIZED)+ atomic_inc(&suspend_block_count);++ atomic_inc(¤t_event_num);+}+EXPORT_SYMBOL(suspend_block);++/**+ * suspend_unblock() - Unblock suspend+ * @blocker: The suspend blocker to unblock.+ *+ * If no other suspend blockers block suspend, the system will suspend.+ */+void suspend_unblock(struct suspend_blocker *blocker)+{+ WARN_ON(!(atomic_read(&blocker->flags) & SB_INITIALIZED));++ if (debug_mask & DEBUG_SUSPEND_BLOCKER)+ pr_info("suspend_unblock: %s\n", blocker->name);++ if (atomic_cmpxchg(&blocker->flags, SB_INITIALIZED | SB_ACTIVE,+ SB_INITIALIZED) == (SB_INITIALIZED | SB_ACTIVE))+ if (atomic_dec_and_test(&suspend_block_count))+ queue_work(suspend_work_queue, &suspend_work);+}+EXPORT_SYMBOL(suspend_unblock);++/**+ * suspend_blocker_is_active() - Test if a suspend blocker is blocking suspend+ * @blocker: The suspend blocker to check.+ *+ * Returns true if the suspend_blocker is currently active.+ */+bool suspend_blocker_is_active(struct suspend_blocker *blocker)+{+ WARN_ON(!(atomic_read(&blocker->flags) & SB_INITIALIZED));++ return !!(atomic_read(&blocker->flags) & SB_ACTIVE);+}+EXPORT_SYMBOL(suspend_blocker_is_active);++void request_suspend_state(suspend_state_t state)+{+ unsigned long irqflags;+ spin_lock_irqsave(&state_lock, irqflags);+ if (debug_mask & DEBUG_USER_STATE)+ pr_info_time("request_suspend_state: %s (%d->%d) at %lld ",+ state != PM_SUSPEND_ON ? "sleep" : "wakeup",+ requested_suspend_state, state,+ ktime_to_ns(ktime_get()));+ requested_suspend_state = state;+ if (state == PM_SUSPEND_ON)+ suspend_block(&main_suspend_blocker);+ else+ suspend_unblock(&main_suspend_blocker);+ spin_unlock_irqrestore(&state_lock, irqflags);+}++static int __init suspend_block_init(void)+{+ suspend_work_queue = create_singlethread_workqueue("suspend");+ if (!suspend_work_queue)+ return -ENOMEM;++ suspend_blocker_init(&main_suspend_blocker, "main");+ suspend_block(&main_suspend_blocker);+ return 0;+}++core_initcall(suspend_block_init);-- 1.6.1
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