[PATCH v3 6/6] MIPS: kexec: Use prepare method from generic platform as default option

[Dengcheng Zhu <dzhu@wavecomp.com>]

The kexec_prepare method for the generic platform should be applicable to
other platforms. For those otherwise, like Octeon, they will use their own
_machine_kexec_prepare().

Without the default prepare work, platforms other than the generic one will
not be able to automatically set up command line correctly for the new
kernel.

Tested-by: Rachel Mozes <rachel.mozes@intel.com>
Reported-by: Rachel Mozes <rachel.mozes@intel.com>
Signed-off-by: Dengcheng Zhu <dzhu@wavecomp.com>
---
Changes:

* Add LIBFDT to CPU_LOONGSON3 for default_machine_kexec_prepare().

 arch/mips/Kconfig                |  1 +
 arch/mips/generic/Makefile       |  1 -
 arch/mips/generic/kexec.c        | 44 ----------------------------------------
 arch/mips/kernel/machine_kexec.c | 34 ++++++++++++++++++++++++++++++-
 4 files changed, 34 insertions(+), 46 deletions(-)
 delete mode 100644 arch/mips/generic/kexec.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 08c10c5..df62764 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1374,6 +1374,7 @@ config CPU_LOONGSON3
 	select MIPS_L1_CACHE_SHIFT_6
 	select GPIOLIB
 	select SWIOTLB
+	select LIBFDT
 	help
 		The Loongson 3 processor implements the MIPS64R2 instruction
 		set with many extensions.
diff --git a/arch/mips/generic/Makefile b/arch/mips/generic/Makefile
index d03a36f..181aa13 100644
--- a/arch/mips/generic/Makefile
+++ b/arch/mips/generic/Makefile
@@ -15,5 +15,4 @@ obj-y += proc.o
 obj-$(CONFIG_YAMON_DT_SHIM)		+= yamon-dt.o
 obj-$(CONFIG_LEGACY_BOARD_SEAD3)	+= board-sead3.o
 obj-$(CONFIG_LEGACY_BOARD_OCELOT)	+= board-ocelot.o
-obj-$(CONFIG_KEXEC)			+= kexec.o
 obj-$(CONFIG_VIRT_BOARD_RANCHU)		+= board-ranchu.o
diff --git a/arch/mips/generic/kexec.c b/arch/mips/generic/kexec.c
deleted file mode 100644
index 1ca409f..0000000
--- a/arch/mips/generic/kexec.c
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * Copyright (C) 2016 Imagination Technologies
- * Author: Marcin Nowakowski <marcin.nowakowski@mips.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);
diff --git a/arch/mips/kernel/machine_kexec.c b/arch/mips/kernel/machine_kexec.c
index 6e3f7c8..e3efb64 100644
--- a/arch/mips/kernel/machine_kexec.c
+++ b/arch/mips/kernel/machine_kexec.c
@@ -9,6 +9,7 @@
 #include <linux/kexec.h>
 #include <linux/mm.h>
 #include <linux/delay.h>
+#include <linux/libfdt.h>
 
 #include <asm/cacheflush.h>
 #include <asm/page.h>
@@ -65,6 +66,36 @@ static void kexec_image_info(const struct kimage *kimage)
 	}
 }
 
+static int default_machine_kexec_prepare(struct kimage *kimage)
+{
+	int i;
+
+	/*
+	 * In case DTB file is not passed to the new kernel, a flat device
+	 * tree will be created by kexec tool. It holds modified command
+	 * line for the new kernel.
+	 */
+	for (i = 0; i < kimage->nr_segments; i++) {
+		struct fdt_header fdt;
+
+		if (kimage->segment[i].memsz <= sizeof(fdt))
+			continue;
+
+		if (copy_from_user(&fdt, kimage->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)kimage->segment[i].mem);
+		break;
+	}
+
+	return 0;
+}
+
 int
 machine_kexec_prepare(struct kimage *kimage)
 {
@@ -72,7 +103,8 @@ machine_kexec_prepare(struct kimage *kimage)
 
 	if (_machine_kexec_prepare)
 		return _machine_kexec_prepare(kimage);
-	return 0;
+	else
+		return default_machine_kexec_prepare(kimage);
 }
 
 void
-- 
2.7.4