PM: Introduce core framework for run-time PM of I/O devices (rev. 17)

Introduce a core framework for run-time power management of I/O
devices.  Add device run-time PM fields to 'struct dev_pm_info'
and device run-time PM callbacks to 'struct dev_pm_ops'.  Introduce
a run-time PM workqueue and define some device run-time PM helper
functions at the core level.  Document all these things.

Special thanks to Alan Stern for his help with the design and
multiple detailed reviews of the pereceding versions of this patch
and to Magnus Damm for testing feedback.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@igel.co.jp>

1 files changed, 114 insertions, 0 deletions

diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
new file mode 100644
index 000000000000..44087044910f
--- /dev/null
+++ b/include/linux/pm_runtime.h
@@ -0,0 +1,114 @@
+/*
+ * pm_runtime.h - Device run-time power management helper functions.
+ *
+ * Copyright (C) 2009 Rafael J. Wysocki <rjw@sisk.pl>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#ifndef _LINUX_PM_RUNTIME_H
+#define _LINUX_PM_RUNTIME_H
+
+#include <linux/device.h>
+#include <linux/pm.h>
+
+#ifdef CONFIG_PM_RUNTIME
+
+extern struct workqueue_struct *pm_wq;
+
+extern int pm_runtime_idle(struct device *dev);
+extern int pm_runtime_suspend(struct device *dev);
+extern int pm_runtime_resume(struct device *dev);
+extern int pm_request_idle(struct device *dev);
+extern int pm_schedule_suspend(struct device *dev, unsigned int delay);
+extern int pm_request_resume(struct device *dev);
+extern int __pm_runtime_get(struct device *dev, bool sync);
+extern int __pm_runtime_put(struct device *dev, bool sync);
+extern int __pm_runtime_set_status(struct device *dev, unsigned int status);
+extern int pm_runtime_barrier(struct device *dev);
+extern void pm_runtime_enable(struct device *dev);
+extern void __pm_runtime_disable(struct device *dev, bool check_resume);
+
+static inline bool pm_children_suspended(struct device *dev)
+{
+        return dev->power.ignore_children
+                || !atomic_read(&dev->power.child_count);
+}
+
+static inline void pm_suspend_ignore_children(struct device *dev, bool enable)
+{
+        dev->power.ignore_children = enable;
+}
+
+static inline void pm_runtime_get_noresume(struct device *dev)
+{
+        atomic_inc(&dev->power.usage_count);
+}
+
+static inline void pm_runtime_put_noidle(struct device *dev)
+{
+        atomic_add_unless(&dev->power.usage_count, -1, 0);
+}
+
+#else /* !CONFIG_PM_RUNTIME */
+
+static inline int pm_runtime_idle(struct device *dev) { return -ENOSYS; }
+static inline int pm_runtime_suspend(struct device *dev) { return -ENOSYS; }
+static inline int pm_runtime_resume(struct device *dev) { return 0; }
+static inline int pm_request_idle(struct device *dev) { return -ENOSYS; }
+static inline int pm_schedule_suspend(struct device *dev, unsigned int delay)
+{
+        return -ENOSYS;
+}
+static inline int pm_request_resume(struct device *dev) { return 0; }
+static inline int __pm_runtime_get(struct device *dev, bool sync) { return 1; }
+static inline int __pm_runtime_put(struct device *dev, bool sync) { return 0; }
+static inline int __pm_runtime_set_status(struct device *dev,
+                                            unsigned int status) { return 0; }
+static inline int pm_runtime_barrier(struct device *dev) { return 0; }
+static inline void pm_runtime_enable(struct device *dev) {}
+static inline void __pm_runtime_disable(struct device *dev, bool c) {}
+
+static inline bool pm_children_suspended(struct device *dev) { return false; }
+static inline void pm_suspend_ignore_children(struct device *dev, bool en) {}
+static inline void pm_runtime_get_noresume(struct device *dev) {}
+static inline void pm_runtime_put_noidle(struct device *dev) {}
+
+#endif /* !CONFIG_PM_RUNTIME */
+
+static inline int pm_runtime_get(struct device *dev)
+{
+        return __pm_runtime_get(dev, false);
+}
+
+static inline int pm_runtime_get_sync(struct device *dev)
+{
+        return __pm_runtime_get(dev, true);
+}
+
+static inline int pm_runtime_put(struct device *dev)
+{
+        return __pm_runtime_put(dev, false);
+}
+
+static inline int pm_runtime_put_sync(struct device *dev)
+{
+        return __pm_runtime_put(dev, true);
+}
+
+static inline int pm_runtime_set_active(struct device *dev)
+{
+        return __pm_runtime_set_status(dev, RPM_ACTIVE);
+}
+
+static inline void pm_runtime_set_suspended(struct device *dev)
+{
+        __pm_runtime_set_status(dev, RPM_SUSPENDED);
+}
+
+static inline void pm_runtime_disable(struct device *dev)
+{
+        __pm_runtime_disable(dev, true);
+}
+
+#endif