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-4.4/093-MIPS-store-the-appended-dtb-address-in-a-variable.patch b/target/linux/generic/patches-4.4/093-MIPS-store-the-appended-dtb-address-in-a-variable.patch
new file mode 100644
index 0000000000..764c1cb830
--- /dev/null
+++ b/target/linux/generic/patches-4.4/093-MIPS-store-the-appended-dtb-address-in-a-variable.patch
@@ -0,0 +1,132 @@
+From 15f37e1588920e010f20b53f04af94e91b8ee714 Mon Sep 17 00:00:00 2001
+From: Jonas Gorski <jogo@openwrt.org>
+Date: Mon, 20 Jun 2016 11:27:37 +0200
+Subject: [PATCH] MIPS: store the appended dtb address in a variable
+
+Instead of rewriting the arguments to match the UHI spec, store the
+address of a appended or UHI supplied dtb in fw_supplied_dtb.
+
+That way the original bootloader arugments are kept intact while still
+making the use of an appended dtb invisible for mach code.
+
+Mach code can still find out if it is an appended dtb by comparing
+fw_arg1 with fw_supplied_dtb.
+
+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/13699/
+Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
+---
+ arch/mips/ath79/setup.c          |  4 ++--
+ arch/mips/bmips/setup.c          |  4 ++--
+ arch/mips/include/asm/bootinfo.h |  4 ++++
+ arch/mips/kernel/head.S          | 21 ++++++++++++++-------
+ arch/mips/kernel/setup.c         |  4 ++++
+ arch/mips/lantiq/prom.c          |  4 ++--
+ arch/mips/pic32/pic32mzda/init.c |  4 ++--
+ 7 files changed, 30 insertions(+), 15 deletions(-)
+
+--- a/arch/mips/ath79/setup.c
++++ b/arch/mips/ath79/setup.c
+@@ -207,6 +207,8 @@ void __init plat_mem_setup(void)
+ 	fdt_start = fw_getenvl("fdt_start");
+ 	if (fdt_start)
+ 		__dt_setup_arch((void *)KSEG0ADDR(fdt_start));
++	else if (fw_passed_dtb)
++		__dt_setup_arch((void *)KSEG0ADDR(fw_passed_dtb));
+ #ifdef CONFIG_BUILTIN_DTB
+ 	else
+ 		__dt_setup_arch(__dtb_start);
+--- a/arch/mips/bmips/setup.c
++++ b/arch/mips/bmips/setup.c
+@@ -149,8 +149,8 @@ void __init plat_mem_setup(void)
+ 	/* intended to somewhat resemble ARM; see Documentation/arm/Booting */
+ 	if (fw_arg0 == 0 && fw_arg1 == 0xffffffff)
+ 		dtb = phys_to_virt(fw_arg2);
+-	else if (fw_arg0 == -2) /* UHI interface */
+-		dtb = (void *)fw_arg1;
++	else if (fw_passed_dtb) /* UHI interface */
++		dtb = (void *)fw_passed_dtb;
+ 	else if (__dtb_start != __dtb_end)
+ 		dtb = (void *)__dtb_start;
+ 	else
+--- a/arch/mips/include/asm/bootinfo.h
++++ b/arch/mips/include/asm/bootinfo.h
+@@ -127,6 +127,10 @@ extern char arcs_cmdline[COMMAND_LINE_SI
+  */
+ extern unsigned long fw_arg0, fw_arg1, fw_arg2, fw_arg3;
+ 
++#ifdef CONFIG_USE_OF
++extern unsigned long fw_passed_dtb;
++#endif
++
+ /*
+  * Platform memory detection hook called by setup_arch
+  */
+--- a/arch/mips/kernel/head.S
++++ b/arch/mips/kernel/head.S
+@@ -94,21 +94,24 @@ NESTED(kernel_entry, 16, sp)			# kernel
+ 	jr	t0
+ 0:
+ 
++#ifdef CONFIG_USE_OF
+ #ifdef CONFIG_MIPS_RAW_APPENDED_DTB
+-	PTR_LA		t0, __appended_dtb
++	PTR_LA		t2, __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		a1, t0
+-	PTR_LI		a0, -2
+-not_found:
++	lw		t0, (t2)
++	beq		t0, t1, dtb_found
++#endif
++	li		t1, -2
++	beq		a0, t1, dtb_found
++	move		t2, a1
++
++	li		t2, 0
++dtb_found:
+ #endif
+ 	PTR_LA		t0, __bss_start		# clear .bss
+ 	LONG_S		zero, (t0)
+@@ -123,6 +126,10 @@ not_found:
+ 	LONG_S		a2, fw_arg2
+ 	LONG_S		a3, fw_arg3
+ 
++#ifdef CONFIG_USE_OF
++	LONG_S		t2, fw_passed_dtb
++#endif
++
+ 	MTC0		zero, CP0_CONTEXT	# clear context register
+ 	PTR_LA		$28, init_thread_union
+ 	/* Set the SP after an empty pt_regs.  */
+--- a/arch/mips/kernel/setup.c
++++ b/arch/mips/kernel/setup.c
+@@ -814,6 +814,10 @@ void __init setup_arch(char **cmdline_p)
+ unsigned long kernelsp[NR_CPUS];
+ unsigned long fw_arg0, fw_arg1, fw_arg2, fw_arg3;
+ 
++#ifdef CONFIG_USE_OF
++unsigned long fw_passed_dtb;
++#endif
++
+ #ifdef CONFIG_DEBUG_FS
+ struct dentry *mips_debugfs_dir;
+ static int __init debugfs_mips(void)