s390/debugfs: introduce top-level 's390' directory

Introduce a top-level 's390' directory which should be used when
adding new s390 specific debug feature files and/or directories.

This makes hopefully sure that the contents of the s390 directory will
be a bit more structured. Right now we have a couple of top-level
files where it is not easy to tell to which subsystem they belong to.
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/Makefile

@@ -56,7 +56,7 @@ obj-y	+= processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o
 obj-y	+= debug.o irq.o ipl.o dis.o diag.o vdso.o als.o
 obj-y	+= sysinfo.o jump_label.o lgr.o os_info.o machine_kexec.o pgm_check.o
 obj-y	+= runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o
-obj-y	+= entry.o reipl.o relocate_kernel.o
+obj-y	+= entry.o reipl.o relocate_kernel.o kdebugfs.o
 
 extra-y				+= head.o head64.o vmlinux.lds
 

arch/s390/kernel/kdebugfs.c

+#include <linux/debugfs.h>
+#include <linux/export.h>
+#include <linux/init.h>
+
+struct dentry *arch_debugfs_dir;
+EXPORT_SYMBOL(arch_debugfs_dir);
+
+static int __init arch_kdebugfs_init(void)
+{
+	arch_debugfs_dir = debugfs_create_dir("s390", NULL);
+	if (IS_ERR(arch_debugfs_dir))
+		arch_debugfs_dir = NULL;
+	return 0;
+}
+postcore_initcall(arch_kdebugfs_init);