[PATCH v4 6/6] MIPS: kexec: Use prepare method from Generic for UHI platforms

[Dengcheng Zhu <dzhu@wavecomp.com>]

The kexec_prepare method for the Generic platform should be applicable to
others using UHI boot protocol. In arch/mips/Kconfig, "select UHI_BOOT" is
needed for such platforms.

If the platform has its own method for _machine_kexec_prepare(), that one
will be used.

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:

* The kexec_prepare method for the Generic platform is defined as
  uhi_machine_kexec_prepare() for all platforms using UHI boot protocol.

 arch/mips/Kconfig                |  4 +++
 arch/mips/generic/Makefile       |  1 -
 arch/mips/generic/kexec.c        | 44 --------------------------------
 arch/mips/kernel/machine_kexec.c | 38 ++++++++++++++++++++++++++-
 4 files changed, 41 insertions(+), 46 deletions(-)
 delete mode 100644 arch/mips/generic/kexec.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 08c10c518f83..260f2ee083ac 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -129,6 +129,7 @@ config MIPS_GENERIC
 	select USB_UHCI_BIG_ENDIAN_DESC if CPU_BIG_ENDIAN
 	select USB_UHCI_BIG_ENDIAN_MMIO if CPU_BIG_ENDIAN
 	select USE_OF
+	select UHI_BOOT
 	help
 	  Select this to build a kernel which aims to support multiple boards,
 	  generally using a flattened device tree passed from the bootloader
@@ -2907,6 +2908,9 @@ config USE_OF
 	select OF_EARLY_FLATTREE
 	select IRQ_DOMAIN
 
+config UHI_BOOT
+	bool
+
 config BUILTIN_DTB
 	bool
 
diff --git a/arch/mips/generic/Makefile b/arch/mips/generic/Makefile
index d03a36f869a4..181aa1335419 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 1ca409f58929..000000000000
--- 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 c2119e448490..209196b195c5 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>
@@ -23,7 +24,6 @@ static unsigned long reboot_code_buffer;
 
 typedef void (*noretfun_t)(void) __noreturn;
 
-int (*_machine_kexec_prepare)(struct kimage *) = NULL;
 void (*_machine_kexec_shutdown)(void) = NULL;
 void (*_machine_crash_shutdown)(struct pt_regs *regs) = NULL;
 #ifdef CONFIG_SMP
@@ -65,6 +65,42 @@ static void kexec_image_info(const struct kimage *kimage)
 	}
 }
 
+#ifdef CONFIG_UHI_BOOT
+static int uhi_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 *) = uhi_machine_kexec_prepare;
+#else
+int (*_machine_kexec_prepare)(struct kimage *) = NULL;
+#endif /* CONFIG_UHI_BOOT */
+
 int
 machine_kexec_prepare(struct kimage *kimage)
 {
-- 
2.17.1