PM: Provide generic subsystem-level callbacks

There are subsystems whose power management callbacks only need to
invoke the callbacks provided by device drivers.  Still, their system
sleep PM callbacks should play well with the runtime PM callbacks,
so that devices suspended at run time can be left in that state for
a system sleep transition.

Provide a set of generic PM callbacks for such subsystems and
define convenience macros for populating dev_pm_ops structures.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

2 files changed, 234 insertions, 0 deletions

diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index 3ce3519e8f30..89de75325cea 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -1,6 +1,7 @@
 obj-$(CONFIG_PM)        += sysfs.o
 obj-$(CONFIG_PM_SLEEP)  += main.o
 obj-$(CONFIG_PM_RUNTIME)        += runtime.o
+obj-$(CONFIG_PM_OPS)    += generic_ops.o
 obj-$(CONFIG_PM_TRACE_RTC)      += trace.o
 
 ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
diff --git a/drivers/base/power/generic_ops.c b/drivers/base/power/generic_ops.c
new file mode 100644
index 000000000000..4b29d4981253
--- /dev/null
+++ b/drivers/base/power/generic_ops.c
@@ -0,0 +1,233 @@
+/*
+ * drivers/base/power/generic_ops.c - Generic PM callbacks for subsystems
+ *
+ * Copyright (c) 2010 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+
+#ifdef CONFIG_PM_RUNTIME
+/**
+ * pm_generic_runtime_idle - Generic runtime idle callback for subsystems.
+ * @dev: Device to handle.
+ *
+ * If PM operations are defined for the @dev's driver and they include
+ * ->runtime_idle(), execute it and return its error code, if nonzero.
+ * Otherwise, execute pm_runtime_suspend() for the device and return 0.
+ */
+int pm_generic_runtime_idle(struct device *dev)
+{
+        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
+
+        if (pm && pm->runtime_idle) {
+                int ret = pm->runtime_idle(dev);
+                if (ret)
+                        return ret;
+        }
+
+        pm_runtime_suspend(dev);
+        return 0;
+}
+EXPORT_SYMBOL_GPL(pm_generic_runtime_idle);
+
+/**
+ * pm_generic_runtime_suspend - Generic runtime suspend callback for subsystems.
+ * @dev: Device to suspend.
+ *
+ * If PM operations are defined for the @dev's driver and they include
+ * ->runtime_suspend(), execute it and return its error code.  Otherwise,
+ * return -EINVAL.
+ */
+int pm_generic_runtime_suspend(struct device *dev)
+{
+        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
+        int ret;
+
+        ret = pm && pm->runtime_suspend ? pm->runtime_suspend(dev) : -EINVAL;
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(pm_generic_runtime_suspend);
+
+/**
+ * pm_generic_runtime_resume - Generic runtime resume callback for subsystems.
+ * @dev: Device to resume.
+ *
+ * If PM operations are defined for the @dev's driver and they include
+ * ->runtime_resume(), execute it and return its error code.  Otherwise,
+ * return -EINVAL.
+ */
+int pm_generic_runtime_resume(struct device *dev)
+{
+        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
+        int ret;
+
+        ret = pm && pm->runtime_resume ? pm->runtime_resume(dev) : -EINVAL;
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(pm_generic_runtime_resume);
+#endif /* CONFIG_PM_RUNTIME */
+
+#ifdef CONFIG_PM_SLEEP
+/**
+ * __pm_generic_call - Generic suspend/freeze/poweroff/thaw subsystem callback.
+ * @dev: Device to handle.
+ * @event: PM transition of the system under way.
+ *
+ * If the device has not been suspended at run time, execute the
+ * suspend/freeze/poweroff/thaw callback provided by its driver, if defined, and
+ * return its error code.  Otherwise, return zero.
+ */
+static int __pm_generic_call(struct device *dev, int event)
+{
+        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
+        int (*callback)(struct device *);
+
+        if (!pm || pm_runtime_suspended(dev))
+                return 0;
+
+        switch (event) {
+        case PM_EVENT_SUSPEND:
+                callback = pm->suspend;
+                break;
+        case PM_EVENT_FREEZE:
+                callback = pm->freeze;
+                break;
+        case PM_EVENT_HIBERNATE:
+                callback = pm->poweroff;
+                break;
+        case PM_EVENT_THAW:
+                callback = pm->thaw;
+                break;
+        default:
+                callback = NULL;
+                break;
+        }
+
+        return callback ? callback(dev) : 0;
+}
+
+/**
+ * pm_generic_suspend - Generic suspend callback for subsystems.
+ * @dev: Device to suspend.
+ */
+int pm_generic_suspend(struct device *dev)
+{
+        return __pm_generic_call(dev, PM_EVENT_SUSPEND);
+}
+EXPORT_SYMBOL_GPL(pm_generic_suspend);
+
+/**
+ * pm_generic_freeze - Generic freeze callback for subsystems.
+ * @dev: Device to freeze.
+ */
+int pm_generic_freeze(struct device *dev)
+{
+        return __pm_generic_call(dev, PM_EVENT_FREEZE);
+}
+EXPORT_SYMBOL_GPL(pm_generic_freeze);
+
+/**
+ * pm_generic_poweroff - Generic poweroff callback for subsystems.
+ * @dev: Device to handle.
+ */
+int pm_generic_poweroff(struct device *dev)
+{
+        return __pm_generic_call(dev, PM_EVENT_HIBERNATE);
+}
+EXPORT_SYMBOL_GPL(pm_generic_poweroff);
+
+/**
+ * pm_generic_thaw - Generic thaw callback for subsystems.
+ * @dev: Device to thaw.
+ */
+int pm_generic_thaw(struct device *dev)
+{
+        return __pm_generic_call(dev, PM_EVENT_THAW);
+}
+EXPORT_SYMBOL_GPL(pm_generic_thaw);
+
+/**
+ * __pm_generic_resume - Generic resume/restore callback for subsystems.
+ * @dev: Device to handle.
+ * @event: PM transition of the system under way.
+ *
+ * Execute the resume/resotre callback provided by the @dev's driver, if
+ * defined.  If it returns 0, change the device's runtime PM status to 'active'.
+ * Return the callback's error code.
+ */
+static int __pm_generic_resume(struct device *dev, int event)
+{
+        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
+        int (*callback)(struct device *);
+        int ret;
+
+        if (!pm)
+                return 0;
+
+        switch (event) {
+        case PM_EVENT_RESUME:
+                callback = pm->resume;
+                break;
+        case PM_EVENT_RESTORE:
+                callback = pm->restore;
+                break;
+        default:
+                callback = NULL;
+                break;
+        }
+
+        if (!callback)
+                return 0;
+
+        ret = callback(dev);
+        if (!ret) {
+                pm_runtime_disable(dev);
+                pm_runtime_set_active(dev);
+                pm_runtime_enable(dev);
+        }
+
+        return ret;
+}
+
+/**
+ * pm_generic_resume - Generic resume callback for subsystems.
+ * @dev: Device to resume.
+ */
+int pm_generic_resume(struct device *dev)
+{
+        return __pm_generic_resume(dev, PM_EVENT_RESUME);
+}
+EXPORT_SYMBOL_GPL(pm_generic_resume);
+
+/**
+ * pm_generic_restore - Generic restore callback for subsystems.
+ * @dev: Device to restore.
+ */
+int pm_generic_restore(struct device *dev)
+{
+        return __pm_generic_resume(dev, PM_EVENT_RESTORE);
+}
+EXPORT_SYMBOL_GPL(pm_generic_restore);
+#endif /* CONFIG_PM_SLEEP */
+
+struct dev_pm_ops generic_subsys_pm_ops = {
+#ifdef CONFIG_PM_SLEEP
+        .suspend = pm_generic_suspend,
+        .resume = pm_generic_resume,
+        .freeze = pm_generic_freeze,
+        .thaw = pm_generic_thaw,
+        .poweroff = pm_generic_poweroff,
+        .restore = pm_generic_restore,
+#endif
+#ifdef CONFIG_PM_RUNTIME
+        .runtime_suspend = pm_generic_runtime_suspend,
+        .runtime_resume = pm_generic_runtime_resume,
+        .runtime_idle = pm_generic_runtime_idle,
+#endif
+};
+EXPORT_SYMBOL_GPL(generic_subsys_pm_ops);