Driver core: platform_driver_probe(), can save codespace

This defines a new platform_driver_probe() method allowing the driver's
probe() method, and its support code+data, to safely live in __init
sections for typical system configurations.

Many system-on-chip processors could benefit from this API, to the tune
of recovering hundreds to thousands of bytes per driver.  That's memory
which is currently wasted holding code which can never be called after
system startup, yet can not be removed.   It can't be removed because of
the linkage requirement that pointers to init section code (like, ideally,
probe support) must not live in other sections (like driver method tables)
after those pointers would be invalid.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index 29cd6dee13db..20f47b81d3fa 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -58,6 +58,12 @@ struct platform_driver {
 extern int platform_driver_register(struct platform_driver *);
 extern void platform_driver_unregister(struct platform_driver *);
 
+/* non-hotpluggable platform devices may use this so that probe() and
+ * its support may live in __init sections, conserving runtime memory.
+ */
+extern int platform_driver_probe(struct platform_driver *driver,
+                int (*probe)(struct platform_device *));
+
 #define platform_get_drvdata(_dev)      dev_get_drvdata(&(_dev)->dev)
 #define platform_set_drvdata(_dev,data) dev_set_drvdata(&(_dev)->dev, (data))