miscdevice: Add helper macro for misc device boilerplate

Many modules call misc_register and misc_deregister in its module init
and exit methods without any additional code. This ends up being
boilerplate. This patch adds helper macro module_misc_device(), that
replaces module_init()/ module_exit() with template functions.

This patch also converts drivers to use new macro.

Change since v1:
Add device.h include in miscdevice.h as module_driver macro was not
available from other include files in some architectures.

Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm/common/bL_switcher_dummy_if.c

@@ -56,16 +56,4 @@ static struct miscdevice bL_switcher_device = {
 	"b.L_switcher",
 	&bL_switcher_fops
 };
-
-static int __init bL_switcher_dummy_if_init(void)
-{
-	return misc_register(&bL_switcher_device);
-}
-
-static void __exit bL_switcher_dummy_if_exit(void)
-{
-	misc_deregister(&bL_switcher_device);
-}
-
-module_init(bL_switcher_dummy_if_init);
-module_exit(bL_switcher_dummy_if_exit);
+module_misc_device(bL_switcher_device);

arch/blackfin/mach-bf561/coreb.c

@@ -59,18 +59,7 @@ static struct miscdevice coreb_dev = {
 	.name  = "coreb",
 	.fops  = &coreb_fops,
 };
-
-static int __init bf561_coreb_init(void)
-{
-	return misc_register(&coreb_dev);
-}
-module_init(bf561_coreb_init);
-
-static void __exit bf561_coreb_exit(void)
-{
-	misc_deregister(&coreb_dev);
-}
-module_exit(bf561_coreb_exit);
+module_misc_device(coreb_dev);
 
 MODULE_AUTHOR("Bas Vermeulen <bvermeul@blackstar.xs4all.nl>");
 MODULE_DESCRIPTION("BF561 Core B Support");

drivers/hid/uhid.c

@@ -779,19 +779,8 @@ static struct miscdevice uhid_misc = {
 	.minor		= UHID_MINOR,
 	.name		= UHID_NAME,
 };
+module_misc_device(uhid_misc);
 
-static int __init uhid_init(void)
-{
-	return misc_register(&uhid_misc);
-}
-
-static void __exit uhid_exit(void)
-{
-	misc_deregister(&uhid_misc);
-}
-
-module_init(uhid_init);
-module_exit(uhid_exit);
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");

drivers/input/misc/uinput.c

@@ -1013,23 +1013,12 @@ static struct miscdevice uinput_misc = {
 	.minor		= UINPUT_MINOR,
 	.name		= UINPUT_NAME,
 };
+module_misc_device(uinput_misc);
+
 MODULE_ALIAS_MISCDEV(UINPUT_MINOR);
 MODULE_ALIAS("devname:" UINPUT_NAME);
 
-static int __init uinput_init(void)
-{
-	return misc_register(&uinput_misc);
-}
-
-static void __exit uinput_exit(void)
-{
-	misc_deregister(&uinput_misc);
-}
-
 MODULE_AUTHOR("Aristeu Sergio Rozanski Filho");
 MODULE_DESCRIPTION("User level driver support for input subsystem");
 MODULE_LICENSE("GPL");
 MODULE_VERSION("0.3");
-
-module_init(uinput_init);
-module_exit(uinput_exit);

drivers/s390/char/sclp_ctl.c

@@ -126,21 +126,4 @@ static struct miscdevice sclp_ctl_device = {
 	.name = "sclp",
 	.fops = &sclp_ctl_fops,
 };
-
-/*
- * Register sclp_ctl misc device
- */
-static int __init sclp_ctl_init(void)
-{
-	return misc_register(&sclp_ctl_device);
-}
-module_init(sclp_ctl_init);
-
-/*
- * Deregister sclp_ctl misc device
- */
-static void __exit sclp_ctl_exit(void)
-{
-	misc_deregister(&sclp_ctl_device);
-}
-module_exit(sclp_ctl_exit);
+module_misc_device(sclp_ctl_device);

drivers/vhost/test.c

@@ -322,18 +322,7 @@ static struct miscdevice vhost_test_misc = {
 	"vhost-test",
 	&vhost_test_fops,
 };
-
-static int vhost_test_init(void)
-{
-	return misc_register(&vhost_test_misc);
-}
-module_init(vhost_test_init);
-
-static void vhost_test_exit(void)
-{
-	misc_deregister(&vhost_test_misc);
-}
-module_exit(vhost_test_exit);
+module_misc_device(vhost_test_misc);
 
 MODULE_VERSION("0.0.1");
 MODULE_LICENSE("GPL v2");

include/linux/miscdevice.h

@@ -3,6 +3,7 @@
 #include <linux/major.h>
 #include <linux/list.h>
 #include <linux/types.h>
+#include <linux/device.h>
 
 /*
  *	These allocations are managed by device@lanana.org. If you use an
@@ -70,6 +71,13 @@ struct miscdevice  {
 extern int misc_register(struct miscdevice *misc);
 extern void misc_deregister(struct miscdevice *misc);
 
+/*
+ * Helper macro for drivers that don't do anything special in module init / exit
+ * call. This helps in eleminating of boilerplate code.
+ */
+#define module_misc_device(__misc_device) \
+	module_driver(__misc_device, misc_register, misc_deregister)
+
 #define MODULE_ALIAS_MISCDEV(minor)				\
 	MODULE_ALIAS("char-major-" __stringify(MISC_MAJOR)	\
 	"-" __stringify(minor))