MIPS: Declare mips_debugfs_dir in a header

We have many extern declarations of mips_debugfs_dir through arch/mips/
in various C files. Unify them by declaring mips_debugfs_dir in a
header, including it in each affected C file & removing the duplicate
declarations.

Signed-off-by: Paul Burton <[e-mail]>
Cc: [e-mail]
Cc: Steven J. Hill <[e-mail]>
Cc: Alexander Sverdlin <[e-mail]>
Cc: Masahiro Yamada <[e-mail]>
Cc: Leonid Yegoshin <[e-mail]>
Cc: Maciej W. Rozycki <[e-mail]>
Cc: [e-mail]
Cc: Joe Perches <[e-mail]>
Cc: Jaedon Shin <[e-mail]>
Cc: James Hogan <[e-mail]>
Cc: David Daney <[e-mail]>
Cc: Zubair Lutfullah Kakakhel <[e-mail]>
Cc: Markos Chandras <[e-mail]>
Cc: James Cowgill <[e-mail]>
Patchwork: https://patchwork.linux-mips.org/patch/11181/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/include/asm/debug.h

···
+/*
+ * Copyright (C) 2015 Imagination Technologies
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#ifndef __MIPS_ASM_DEBUG_H__
+#define __MIPS_ASM_DEBUG_H__
+
+#include <linux/dcache.h>
+
+/*
+ * mips_debugfs_dir corresponds to the "mips" directory at the top level
+ * of the DebugFS hierarchy. MIPS-specific DebugFS entires should be
+ * placed beneath this directory.
+ */
+extern struct dentry *mips_debugfs_dir;
+
+#endif /* __MIPS_ASM_DEBUG_H__ */

arch/mips/kernel/mips-r2-to-r6-emul.c

···
 #include <asm/asm.h>
 #include <asm/branch.h>
 #include <asm/break.h>
+#include <asm/debug.h>
 #include <asm/fpu.h>
 #include <asm/fpu_emulator.h>
 #include <asm/inst.h>
···
 
 static int __init mipsr2_init_debugfs(void)
 {
-	extern struct dentry	*mips_debugfs_dir;
 	struct dentry		*mipsr2_emul;
 
 	if (!mips_debugfs_dir)

arch/mips/kernel/segment.c

···
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
 #include <asm/cpu.h>
+#include <asm/debug.h>
 #include <asm/mipsregs.h>
 
 static void build_segment_config(char *str, unsigned int cfg)
···
 
 static int __init segments_info(void)
 {
-	extern struct dentry *mips_debugfs_dir;
 	struct dentry *segments;
 
 	if (cpu_has_segments) {

arch/mips/kernel/setup.c

···
 #include <asm/cache.h>
 #include <asm/cdmm.h>
 #include <asm/cpu.h>
+#include <asm/debug.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/smp-ops.h>

arch/mips/kernel/spinlock_test.c

···
 #include <linux/debugfs.h>
 #include <linux/export.h>
 #include <linux/spinlock.h>
-
+#include <asm/debug.h>
 
 static int ss_get(void *data, u64 *val)
 {
···
 
 DEFINE_SIMPLE_ATTRIBUTE(fops_multi, multi_get, NULL, "%llu\n");
 
-
-extern struct dentry *mips_debugfs_dir;
 static int __init spinlock_test(void)
 {
 	struct dentry *d;

arch/mips/kernel/unaligned.c

···
 #include <asm/branch.h>
 #include <asm/byteorder.h>
 #include <asm/cop2.h>
+#include <asm/debug.h>
 #include <asm/fpu.h>
 #include <asm/fpu_emulator.h>
 #include <asm/inst.h>
···
 }
 
 #ifdef CONFIG_DEBUG_FS
-extern struct dentry *mips_debugfs_dir;
 static int __init debugfs_unaligned(void)
 {
 	struct dentry *d;

arch/mips/math-emu/me-debugfs.c

···
 #include <linux/init.h>
 #include <linux/percpu.h>
 #include <linux/types.h>
+#include <asm/debug.h>
 #include <asm/fpu_emulator.h>
 #include <asm/local.h>
 
···
 }
 DEFINE_SIMPLE_ATTRIBUTE(fops_fpuemu_stat, fpuemu_stat_get, NULL, "%llu\n");
 
-extern struct dentry *mips_debugfs_dir;
 static int __init debugfs_fpuemu(void)
 {
 	struct dentry *d, *dir;