greybus: register the bus with the driver core and add framework for debugfs files.

drivers/staging/greybus/Makefile

@@ -1,4 +1,4 @@
-greybus-y := core.o gbuf.o i2c-gb.o gpio-gb.o sdio-gb.o uart-gb.o
+greybus-y := core.o gbuf.o debugfs.o i2c-gb.o gpio-gb.o sdio-gb.o uart-gb.o
 
 obj-m += greybus.o
 obj-m += es1-ap-usb.o

drivers/staging/greybus/core.c

@@ -86,7 +86,7 @@ static int greybus_uevent(struct device *dev, struct kobj_uevent_env *env)
 	return 0;
 }
 
-struct bus_type greybus_bus_type = {
+static struct bus_type greybus_bus_type = {
 	.name =		"greybus",
 	.match =	greybus_device_match,
 	.uevent =	greybus_uevent,
@@ -199,16 +199,36 @@ static int __init gb_init(void)
 {
 	int retval;
 
-	retval = gb_tty_init();
+	retval = greybus_debugfs_init();
 	if (retval)
 		return retval;
 
+	retval = bus_register(&greybus_bus_type);
+	if (retval)
+		goto error_bus;
+
+	// FIXME - more gb core init goes here
+
+	retval = gb_tty_init();
+	if (retval)
+		goto error_tty;
+
 	return 0;
+
+error_tty:
+	bus_unregister(&greybus_bus_type);
+
+error_bus:
+	greybus_debugfs_cleanup();
+
+	return retval;
 }
 
 static void __exit gb_exit(void)
 {
 	gb_tty_exit();
+	bus_unregister(&greybus_bus_type);
+	greybus_debugfs_cleanup();
 }
 
 module_init(gb_init);

drivers/staging/greybus/debugfs.c

@@ -0,0 +1,34 @@
+/*
+ * Greybus debugfs code
+ *
+ * Copyright 2014 Google Inc.
+ *
+ * Released under the GPLv2 only.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/debugfs.h>
+
+#include "greybus.h"
+
+static struct dentry *gb_debug_root;
+
+int greybus_debugfs_init(void)
+{
+	gb_debug_root = debugfs_create_dir("greybus", NULL);
+	if (!gb_debug_root)
+		return -ENOENT;
+
+	return 0;
+}
+
+void greybus_debugfs_cleanup(void)
+{
+	debugfs_remove_recursive(gb_debug_root);
+}

drivers/staging/greybus/greybus.h

@@ -174,10 +174,10 @@ void greybus_deregister(struct greybus_driver *driver);
 #define module_greybus_driver(__greybus_driver)	\
 	module_driver(__greybus_driver, greybus_register, greybus_deregister)
 
-extern struct bus_type greybus_bus_type;
-
 int greybus_disabled(void);
 
+int greybus_debugfs_init(void);
+void greybus_debugfs_cleanup(void);
 
 #endif /* __KERNEL__ */
 #endif /* __LINUX_GREYBUS_H */