linux-kernel - [PATCH v2 1/2] [media] rc-core: Add inlined stubs for core rc

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Message-Id: <20170412153956.13329-1-lee.jones@linaro.org>
Date:   Wed, 12 Apr 2017 16:39:55 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     hans.verkuil@...co.com, mchehab@...nel.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        patrice.chotard@...com, linux@...linux.org.uk,
        Lee Jones <lee.jones@...aro.org>
Subject: [PATCH v2 1/2] [media] rc-core: Add inlined stubs for core rc_* functions

Currently users have to use all sorts of ugly #ifery within
their drivers in order to avoid linking issues at build time.
This patch allows users to safely call these functions when
!CONFIG_RC_CORE and make decisions based on the return value
instead.  This is a much more common and clean way of doing
things within the Linux kernel.

Signed-off-by: Lee Jones <lee.jones@...aro.org>
---

v1 => v2
  - Use '#if IF_ENABLED()' instead of '#ifdef' in order to do the
    right thing, even when CONFIG_RC_CORE=m.
  
include/media/rc-core.h | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/include/media/rc-core.h b/include/media/rc-core.h
index 73ddd721..f176a9e 100644
--- a/include/media/rc-core.h
+++ b/include/media/rc-core.h
@@ -209,7 +209,14 @@ struct rc_dev {
  * @rc_driver_type: specifies the type of the RC output to be allocated
  * returns a pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 struct rc_dev *rc_allocate_device(enum rc_driver_type);
+#else
+static inline struct rc_dev *rc_allocate_device(int unused)
+{
+	return NULL;
+}
+#endif
 
 /**
  * devm_rc_allocate_device - Managed RC device allocation
@@ -218,21 +225,42 @@ struct rc_dev *rc_allocate_device(enum rc_driver_type);
  * @rc_driver_type: specifies the type of the RC output to be allocated
  * returns a pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 struct rc_dev *devm_rc_allocate_device(struct device *dev, enum rc_driver_type);
+#else
+static inline struct rc_dev *devm_rc_allocate_device(struct device *dev, int unused)
+{
+	return NULL;
+}
+#endif
 
 /**
  * rc_free_device - Frees a RC device
  *
  * @dev: pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 void rc_free_device(struct rc_dev *dev);
+#else
+static inline void rc_free_device(struct rc_dev *dev)
+{
+	return;
+}
+#endif
 
 /**
  * rc_register_device - Registers a RC device
  *
  * @dev: pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 int rc_register_device(struct rc_dev *dev);
+#else
+static inline int rc_register_device(struct rc_dev *dev)
+{
+	return -EOPNOTSUPP;
+}
+#endif
 
 /**
  * devm_rc_register_device - Manageded registering of a RC device
@@ -240,14 +268,28 @@ int rc_register_device(struct rc_dev *dev);
  * @parent: pointer to struct device.
  * @dev: pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 int devm_rc_register_device(struct device *parent, struct rc_dev *dev);
+#else
+static inline int devm_rc_register_device(struct device *parent, struct rc_dev *dev)
+{
+	return -EOPNOTSUPP;
+}
+#endif
 
 /**
  * rc_unregister_device - Unregisters a RC device
  *
  * @dev: pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 void rc_unregister_device(struct rc_dev *dev);
+#else
+static inline void rc_unregister_device(struct rc_dev *dev)
+{
+	return;
+}
+#endif
 
 /**
  * rc_open - Opens a RC device
-- 
2.9.3