[PATCH 2/4] driver: core: platform: add subsys_platform_driver() macro

[Brian Masney]

Add a new macro subsys_platform_driver() to eliminate some boilerplate
code in drivers that need to register earlier in the boot at the
subsys_initcall level.

Signed-off-by: Brian Masney <bmasney@xxxxxxxxxx>
Assisted-by: Claude:claude-opus-4-8
---
 include/linux/platform_device.h | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index 3d5bbcbae730..3bd0f1f0d870 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -344,6 +344,19 @@ static inline void platform_set_drvdata(struct platform_device *pdev,
 #define builtin_platform_driver(__platform_driver) \
 	builtin_driver(__platform_driver, platform_driver_register)
 
+/*
+ * subsys_platform_driver() - Helper macro for drivers that don't do anything
+ * special in module init/exit but need to register earlier, at
+ * subsys_initcall level, when built in.  This eliminates a lot of
+ * boilerplate.  Each driver may only use this macro once, and calling it
+ * replaces module_init() and module_exit().  This is meant to be a parallel
+ * of module_platform_driver() above, but with the init call promoted to
+ * subsys_initcall() so built-in providers are available earlier during boot.
+ */
+#define subsys_platform_driver(__platform_driver) \
+	subsys_driver(__platform_driver, platform_driver_register, \
+			platform_driver_unregister)
+
 /* 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
@@ -376,6 +389,23 @@ static int __init __platform_driver##_init(void) \
 } \
 device_initcall(__platform_driver##_init); \
 
+/*
+ * subsys_platform_driver_probe() - Helper macro for drivers that don't do
+ * anything special in device init and have no exit, but need to register
+ * earlier, at subsys_initcall level.  This eliminates some boilerplate.  Each
+ * driver may only use this macro once, and using it replaces subsys_initcall.
+ * This is meant to be a parallel of builtin_platform_driver_probe above, but
+ * with the init call promoted to subsys_initcall so the provider is available
+ * earlier during boot.
+ */
+#define subsys_platform_driver_probe(__platform_driver, __platform_probe) \
+static int __init __platform_driver##_init(void) \
+{ \
+	return platform_driver_probe(&(__platform_driver), \
+				     __platform_probe);    \
+} \
+subsys_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, KBUILD_MODNAME)
 extern struct platform_device *__platform_create_bundle(

-- 
2.55.0