MIPS: ZBOOT: copy appended dtb to the end of the kernel

Instead of rewriting the arguments, just move the appended dtb to where
the decompressed kernel expects it. This eliminates the need for special
casing vmlinuz.bin appended dtb files.

Signed-off-by: Jonas Gorski <jogo@openwrt.org>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: John Crispin <john@phrozen.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Alban Bedel <albeu@free.fr>
Cc: Daniel Gimpelevich <daniel@gimpelevich.san-francisco.ca.us>
Cc: Antony Pavlov <antonynpavlov@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13698/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 17 insertions, 16 deletions

diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c
index 080cd53bac36..fdf99e9dd4c3 100644
--- a/arch/mips/boot/compressed/decompress.c
+++ b/arch/mips/boot/compressed/decompress.c
@@ -14,6 +14,7 @@
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
+#include <linux/libfdt.h>
 
 #include <asm/addrspace.h>
 
@@ -36,6 +37,8 @@ extern void puthex(unsigned long long val);
 #define puthex(val) do {} while (0)
 #endif
 
+extern char __appended_dtb[];
+
 void error(char *x)
 {
         puts("\n\n");
@@ -114,6 +117,20 @@ void decompress_kernel(unsigned long boot_heap_start)
         __decompress((char *)zimage_start, zimage_size, 0, 0,
                    (void *)VMLINUX_LOAD_ADDRESS_ULL, 0, 0, error);
 
+        if (IS_ENABLED(CONFIG_MIPS_RAW_APPENDED_DTB) &&
+            fdt_magic((void *)&__appended_dtb) == FDT_MAGIC) {
+                unsigned int image_size, dtb_size;
+
+                dtb_size = fdt_totalsize((void *)&__appended_dtb);
+
+                /* last four bytes is always image size in little endian */
+                image_size = le32_to_cpup((void *)&__image_end - 4);
+
+                /* copy dtb to where the booted kernel will expect it */
+                memcpy((void *)VMLINUX_LOAD_ADDRESS_ULL + image_size,
+                       __appended_dtb, dtb_size);
+        }
+
         /* FIXME: should we flush cache here? */
         puts("Now, booting the kernel...\n");
 }
diff --git a/arch/mips/boot/compressed/head.S b/arch/mips/boot/compressed/head.S
index c580e853b9fb..409cb483a9ff 100644
--- a/arch/mips/boot/compressed/head.S
+++ b/arch/mips/boot/compressed/head.S
@@ -25,22 +25,6 @@ start:
         move    s2, a2
         move    s3, a3
 
-#ifdef CONFIG_MIPS_ZBOOT_APPENDED_DTB
-        PTR_LA  t0, __appended_dtb
-#ifdef CONFIG_CPU_BIG_ENDIAN
-        li      t1, 0xd00dfeed
-#else
-        li      t1, 0xedfe0dd0
-#endif
-        lw      t2, (t0)
-        bne     t1, t2, not_found
-         nop
-
-        move    s1, t0
-        PTR_LI  s0, -2
-not_found:
-#endif
-
         /* Clear BSS */
         PTR_LA  a0, _edata
         PTR_LA  a2, _end