MIPS: kexec: Use prepare method from Generic for UHI platforms

Out-of-tree platforms may not be based on Generic as shown in customer
communication. Share the prepare method with all using UHI boot protocol,
and put into machine_kexec.c.

The benefit is that, when having kexec_args related problems, developers
will naturally look into machine_kexec.c, where "CONFIG_UHI_BOOT" will be
found, prompting them to add "select UHI_BOOT" to the platform Kconfig. It
would otherwise require a lot debugging or online searching to be aware
that the solution is in Generic code.

Tested-by: Rachel Mozes <rachel.mozes@intel.com>
Reported-by: Rachel Mozes <rachel.mozes@intel.com>
Signed-off-by: Dengcheng Zhu <dzhu@wavecomp.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/20569/
Cc: pburton@wavecomp.com
Cc: ralf@linux-mips.org
Cc: linux-mips@linux-mips.org

4 files changed, 45 insertions, 46 deletions

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index f744d25f7423..ce55c3c2d10d 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -133,6 +133,7 @@ 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
@@ -2899,6 +2900,9 @@ 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 14ced77c5ef6..35175eb2e8b0 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>
@@ -28,7 +29,6 @@ atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
 void (*_crash_smp_send_stop)(void) = NULL;
 #endif
 
-int (*_machine_kexec_prepare)(struct kimage *) = NULL;
 void (*_machine_kexec_shutdown)(void) = NULL;
 void (*_machine_crash_shutdown)(struct pt_regs *regs) = NULL;
 
@@ -52,6 +52,46 @@ 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)
 {