[MIPS] kgdb: add arch support for the kernel's kgdb core

The new kgdb architecture specific handler registers and unregisters
dynamically for exceptions depending on when you configure a kgdb I/O
driver.

Aside from initializing the exceptions earlier in the boot process,
kgdb should have no impact on a device when it is compiled in so long
as an I/O module is not configured for use.

There have been quite a number of contributors during the existence of
this patch (see arch/mips/kernel/kgdb.c).  Most recently Jason
re-wrote the mips kgdb logic to use the die notification handlers.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

include/asm-mips/kdebug.h

@@ -1 +1,13 @@
-#include <asm-generic/kdebug.h>
+#ifndef _ASM_MIPS_KDEBUG_H
+#define _ASM_MIPS_KDEBUG_H
+
+#include <linux/notifier.h>
+
+enum die_val {
+	DIE_OOPS = 1,
+	DIE_FP,
+	DIE_TRAP,
+	DIE_RI,
+};
+
+#endif /* _ASM_MIPS_KDEBUG_H */

include/asm-mips/kgdb.h

@@ -0,0 +1,44 @@
+#ifndef __ASM_KGDB_H_
+#define __ASM_KGDB_H_
+
+#ifdef __KERNEL__
+
+#include <asm/sgidefs.h>
+
+#if (_MIPS_ISA == _MIPS_ISA_MIPS1) || (_MIPS_ISA == _MIPS_ISA_MIPS2) || \
+	(_MIPS_ISA == _MIPS_ISA_MIPS32)
+
+#define KGDB_GDB_REG_SIZE 32
+
+#elif (_MIPS_ISA == _MIPS_ISA_MIPS3) || (_MIPS_ISA == _MIPS_ISA_MIPS4) || \
+	(_MIPS_ISA == _MIPS_ISA_MIPS64)
+
+#ifdef CONFIG_32BIT
+#define KGDB_GDB_REG_SIZE 32
+#else /* CONFIG_CPU_32BIT */
+#define KGDB_GDB_REG_SIZE 64
+#endif
+#else
+#error "Need to set KGDB_GDB_REG_SIZE for MIPS ISA"
+#endif /* _MIPS_ISA */
+
+#define BUFMAX			2048
+#if (KGDB_GDB_REG_SIZE == 32)
+#define NUMREGBYTES		(90*sizeof(u32))
+#define NUMCRITREGBYTES		(12*sizeof(u32))
+#else
+#define NUMREGBYTES		(90*sizeof(u64))
+#define NUMCRITREGBYTES		(12*sizeof(u64))
+#endif
+#define BREAK_INSTR_SIZE	4
+#define CACHE_FLUSH_IS_SAFE	0
+
+extern void arch_kgdb_breakpoint(void);
+extern int kgdb_early_setup;
+extern void *saved_vectors[32];
+extern void handle_exception(struct pt_regs *regs);
+extern void breakinst(void);
+
+#endif				/* __KERNEL__ */
+
+#endif /* __ASM_KGDB_H_ */