MIPS: generic/kexec: add support for a DTB passed in a separate buffer

Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14615/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/generic/Makefile

@@ -13,3 +13,4 @@ obj-y += irq.o
 obj-y += proc.o
 
 obj-$(CONFIG_LEGACY_BOARD_SEAD3)	+= board-sead3.o
+obj-$(CONFIG_KEXEC)			+= kexec.o

arch/mips/generic/kexec.c

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2016 Imagination Technologies
+ * Author: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
+ *
+ * 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.
+ */
+
+#include <linux/kexec.h>
+#include <linux/libfdt.h>
+#include <linux/uaccess.h>
+
+static int generic_kexec_prepare(struct kimage *image)
+{
+	int i;
+
+	for (i = 0; i < image->nr_segments; i++) {
+		struct fdt_header fdt;
+
+		if (image->segment[i].memsz <= sizeof(fdt))
+			continue;
+
+		if (copy_from_user(&fdt, image->segment[i].buf, sizeof(fdt)))
+			continue;
+
+		if (fdt_check_header(&fdt))
+			continue;
+
+		kexec_args[0] = -2;
+		kexec_args[1] = (unsigned long)
+			phys_to_virt((unsigned long)image->segment[i].mem);
+		break;
+	}
+	return 0;
+}
+
+static int __init register_generic_kexec(void)
+{
+	_machine_kexec_prepare = generic_kexec_prepare;
+	return 0;
+}
+arch_initcall(register_generic_kexec);