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authorPaul Gortmaker <paul.gortmaker@windriver.com>2015-05-02 03:10:57 +0300
committerPaul Gortmaker <paul.gortmaker@windriver.com>2015-06-16 21:12:37 +0300
commitf309d4443130bf814e991f836e919dca22df37ae (patch)
tree5e34131d7a8ae8f36b3b8e0d521fb1d1b0117338 /include/linux/platform_device.h
parent0f57d86787d8b1076ea8f9cbdddda2a46d534a27 (diff)
downloadlinux-f309d4443130bf814e991f836e919dca22df37ae.tar.xz
platform_device: better support builtin boilerplate avoidance
We have macros that help reduce the boilerplate for modules that register with no extra init/exit complexity other than the most standard use case. However we see an increasing number of non-modular drivers using these modular_driver() type register functions. There are several downsides to this: 1) The code can appear modular to a reader of the code, and they won't know if the code really is modular without checking the Makefile and Kconfig to see if compilation is governed by a bool or tristate. 2) Coders of drivers may be tempted to code up an __exit function that is never used, just in order to satisfy the required three args of the modular registration function. 3) Non-modular code ends up including the <module.h> which increases CPP overhead that they don't need. 4) It hinders us from performing better separation of the module init code and the generic init code. Here we introduce similar macros, with the mapping from module_driver to builtin_driver and similar, so that simple changes of: module_platform_driver() ---> builtin_platform_driver() module_platform_driver_probe() ---> builtin_platform_driver_probe(). can help us avoid #3 above, without having to code up the same __init functions and device_initcall() boilerplate. For non modular code, module_init becomes __initcall. But direct use of __initcall is discouraged, vs. one of the priority categorized subgroups. As __initcall gets mapped onto device_initcall, our use of device_initcall directly in this change means that the runtime impact is zero -- drivers will remain at level 6 in the initcall ordering. Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Diffstat (limited to 'include/linux/platform_device.h')
-rw-r--r--include/linux/platform_device.h23
1 files changed, 23 insertions, 0 deletions
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index 58f1e75ba105..bba08f44cc97 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -222,6 +222,15 @@ static inline void platform_set_drvdata(struct platform_device *pdev,
module_driver(__platform_driver, platform_driver_register, \
platform_driver_unregister)
+/* builtin_platform_driver() - Helper macro for builtin drivers that
+ * don't do anything special in driver init. This eliminates some
+ * boilerplate. Each driver may only use this macro once, and
+ * calling it replaces device_initcall(). Note this is meant to be
+ * a parallel of module_platform_driver() above, but w/o _exit stuff.
+ */
+#define builtin_platform_driver(__platform_driver) \
+ builtin_driver(__platform_driver, platform_driver_register)
+
/* module_platform_driver_probe() - Helper macro for drivers that don't do
* anything special in module init/exit. This eliminates a lot of
* boilerplate. Each module may only use this macro once, and
@@ -240,6 +249,20 @@ static void __exit __platform_driver##_exit(void) \
} \
module_exit(__platform_driver##_exit);
+/* builtin_platform_driver_probe() - Helper macro for drivers that don't do
+ * anything special in device init. This eliminates some boilerplate. Each
+ * driver may only use this macro once, and using it replaces device_initcall.
+ * This is meant to be a parallel of module_platform_driver_probe above, but
+ * without the __exit parts.
+ */
+#define builtin_platform_driver_probe(__platform_driver, __platform_probe) \
+static int __init __platform_driver##_init(void) \
+{ \
+ return platform_driver_probe(&(__platform_driver), \
+ __platform_probe); \
+} \
+device_initcall(__platform_driver##_init); \
+
#define platform_create_bundle(driver, probe, res, n_res, data, size) \
__platform_create_bundle(driver, probe, res, n_res, data, size, THIS_MODULE)
extern struct platform_device *__platform_create_bundle(