kernel: Backport pending appended DTB handling patches

Backport patches from upstream Linux kernel which are making the
kernel stores the appended dtb not in the same resisters as defined in
the UHI specification, use a separate variable on MIPS.

Signed-off-by: Daniel Gimpelevich <daniel@gimpelevich.san-francisco.ca.us>
[some modifications]
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

1 files changed, 132 insertions, 0 deletions

diff --git a/target/linux/generic/patches-4.4/092-MIPS-ZBOOT-copy-appended-dtb-to-the-end-of-the-kerne.patch b/target/linux/generic/patches-4.4/092-MIPS-ZBOOT-copy-appended-dtb-to-the-end-of-the-kerne.patch
new file mode 100644
index 0000000000..71df42992b
--- /dev/null
+++ b/target/linux/generic/patches-4.4/092-MIPS-ZBOOT-copy-appended-dtb-to-the-end-of-the-kerne.patch
@@ -0,0 +1,132 @@
+From b8f54f2cde788623f41d11327688c75aed34092f Mon Sep 17 00:00:00 2001
+From: Jonas Gorski <jogo@openwrt.org>
+Date: Mon, 20 Jun 2016 11:27:36 +0200
+Subject: [PATCH 1/2] 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>
+---
+ arch/mips/Kconfig                      | 22 ++--------------------
+ arch/mips/boot/compressed/decompress.c | 17 +++++++++++++++++
+ arch/mips/boot/compressed/head.S       | 16 ----------------
+ 3 files changed, 19 insertions(+), 36 deletions(-)
+
+--- a/arch/mips/Kconfig
++++ b/arch/mips/Kconfig
+@@ -2752,10 +2752,10 @@ choice
+ 		  the documented boot protocol using a device tree.
+ 
+ 	config MIPS_RAW_APPENDED_DTB
+-		bool "vmlinux.bin"
++		bool "vmlinux.bin or vmlinuz.bin"
+ 		help
+ 		  With this option, the boot code will look for a device tree binary
+-		  DTB) appended to raw vmlinux.bin (without decompressor).
++		  DTB) appended to raw vmlinux.bin or vmlinuz.bin.
+ 		  (e.g. cat vmlinux.bin <filename>.dtb > vmlinux_w_dtb).
+ 
+ 		  This is meant as a backward compatibility convenience for those
+@@ -2767,24 +2767,6 @@ choice
+ 		  look like a DTB header after a reboot if no actual DTB is appended
+ 		  to vmlinux.bin.  Do not leave this option active in a production kernel
+ 		  if you don't intend to always append a DTB.
+-
+-	config MIPS_ZBOOT_APPENDED_DTB
+-		bool "vmlinuz.bin"
+-		depends on SYS_SUPPORTS_ZBOOT
+-		help
+-		  With this option, the boot code will look for a device tree binary
+-		  DTB) appended to raw vmlinuz.bin (with decompressor).
+-		  (e.g. cat vmlinuz.bin <filename>.dtb > vmlinuz_w_dtb).
+-
+-		  This is meant as a backward compatibility convenience for those
+-		  systems with a bootloader that can't be upgraded to accommodate
+-		  the documented boot protocol using a device tree.
+-
+-		  Beware that there is very little in terms of protection against
+-		  this option being confused by leftover garbage in memory that might
+-		  look like a DTB header after a reboot if no actual DTB is appended
+-		  to vmlinuz.bin.  Do not leave this option active in a production kernel
+-		  if you don't intend to always append a DTB.
+ endchoice
+ 
+ choice
+--- 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 va
+ #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 boo
+ 	__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");
+ }
+--- 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