[PATCH 1/3] PM: runtime: Define class helpers for automatic PM runtime cleanup

[Takashi Iwai <tiwai@suse.de>]

From: "Rafael J. Wysocki" <rafael@kernel.org>

This patch adds two CLASS macros for the easier use of the
auto-cleanup feature to manage the runtime PM get/put pairs.
With the CLASS macro, pm_runtime_put() (or *_autosuspend) is called
automatically at its scope exit, so you can remove the explicit
pm_runtime_put() call.

Simply put, a code like below

	ret = pm_runtime_resume_and_get(dev);
	if (ret < 0)
		return ret;
	.....
	pm_runtime_put(dev);
	return 0;

can be simplified with CLASS() like:

	CLASS(pm_runtime_resume_and_get, pm)(dev);
	if (IS_ERR(pm))
		return PTR_ERR(pm);
	.....
	return 0;

(see pm_runtime_put() call is gone).

When the original code calls pm_runtime_put_autosuspend(), use
CLASS(pm_runtime_resume_and_get_auto) variant, instead.
e.g. a code like:

	ret = pm_runtime_resume_and_get(dev);
	if (ret < 0)
		return ret;
	.....
	pm_runtime_put_autosuspend(dev);
	return 0;

will be like:

	CLASS(pm_runtime_resume_and_get_auto, pm)(dev);
	if (IS_ERR(pm))
		return PTR_ERR(pm);
	.....
	return 0;

Note that there is no CLASS macro defined for pm_runtime_get_sync().
With the auto-cleanup, we can unify both usages.
You can use CLASS(pm_runtime_resume_and_get) but simply skip the error
check; so a code like below:

	pm_runtime_get_sync(dev);
	.....
	pm_runtime_put(dev);
	return 0;

will become like:

	CLASS(pm_runtime_resume_and_get, pm)(dev);
	.....
	return 0;

Link: https://lore.kernel.org/878qimv24u.wl-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 include/linux/pm_runtime.h | 43 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index d88d6b6ccf5b..637bfda9c2cd 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -532,6 +532,30 @@ static inline int pm_runtime_resume_and_get(struct device *dev)
 	return 0;
 }
 
+/**
+ * pm_runtime_resume_and_get_dev - Resume device and bump up its usage counter.
+ * @dev: Target device.
+ *
+ * Resume @dev synchronously and if that is successful, increment its runtime
+ * PM usage counter.
+ *
+ * Return:
+ * * 0 if the runtime PM usage counter of @dev has been incremented.
+ * * Negative error code otherwise.
+ */
+static inline struct device *pm_runtime_resume_and_get_dev(struct device *dev)
+{
+	int ret;
+
+	ret = __pm_runtime_resume(dev, RPM_GET_PUT);
+	if (ret < 0) {
+		pm_runtime_put_noidle(dev);
+		return ERR_PTR(ret);
+	}
+
+	return dev;
+}
+
 /**
  * pm_runtime_put - Drop device usage counter and queue up "idle check" if 0.
  * @dev: Target device.
@@ -606,6 +630,25 @@ static inline int pm_runtime_put_autosuspend(struct device *dev)
 	return __pm_runtime_put_autosuspend(dev);
 }
 
+/*
+ * The way to use the classes defined below is to define a class variable and
+ * use it going forward for representing the target device until it goes out of
+ * the scope.  For example:
+ *
+ * CLASS(pm_runtime_resume_and_get, active_dev)(dev);
+ * if (IS_ERR(active_dev))
+ *         return PTR_ERR(active_dev);
+ *
+ * ... do something with active_dev (which is guaranteed to never suspend) ...
+ */
+DEFINE_CLASS(pm_runtime_resume_and_get, struct device *,
+	     if (!IS_ERR_OR_NULL(_T)) pm_runtime_put(_T),
+	     pm_runtime_resume_and_get_dev(dev), struct device *dev)
+
+DEFINE_CLASS(pm_runtime_resume_and_get_auto, struct device *,
+	     if (!IS_ERR_OR_NULL(_T)) pm_runtime_put_autosuspend(_T),
+	     pm_runtime_resume_and_get_dev(dev), struct device *dev)
+
 /**
  * pm_runtime_put_sync - Drop device usage counter and run "idle check" if 0.
  * @dev: Target device.
-- 
2.50.1