ipq806x: fix boot freeze on zImage kernel

ARCH_QCOM is using the ARCH_MULTIPLATFORM option, as now recommended
on most ARM architectures. This automatically calculate ZRELADDR by
masking PHYS_OFFSET with 0xf8000000.

On IPQ806x though, the first ~20MB of RAM is reserved for the hardware.
In newer bootloader, when DT is used, this is not a problem, we just
reserve this memory in the device tree. But if the bootloader doesn't
have DT support, then ATAGS have to be used. In this case, the ARM
decompressor will position the kernel in this low mem, which will not be
in the RAM section mapped by the bootloader, which means the kernel will
freeze in the middle of the boot process trying to map the memory.

As a work around, this patch allows disabling AUTO_ZRELADDR when
ARCH_QCOM is selected. It makes the zImage usage possible on bootloaders
which don't support device-tree, which is the case on certain early
IPQ806x based designs.

Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>

SVN-Revision: 45661

1 files changed, 72 insertions, 0 deletions

diff --git a/target/linux/ipq806x/patches-3.18/300-arch-arm-force-ZRELADDR-on-arch-qcom.patch b/target/linux/ipq806x/patches-3.18/300-arch-arm-force-ZRELADDR-on-arch-qcom.patch
new file mode 100644
index 0000000000..82170cde80
--- /dev/null
+++ b/target/linux/ipq806x/patches-3.18/300-arch-arm-force-ZRELADDR-on-arch-qcom.patch
@@ -0,0 +1,72 @@
+From b12e230f09d4481424e6a5d7e2ae566b6954e83f Mon Sep 17 00:00:00 2001
+From: Mathieu Olivari <mathieu@codeaurora.org>
+Date: Wed, 29 Apr 2015 15:21:46 -0700
+Subject: [PATCH] HACK: arch: arm: force ZRELADDR on arch-qcom
+
+ARCH_QCOM is using the ARCH_MULTIPLATFORM option, as now recommended
+on most ARM architectures. This automatically calculate ZRELADDR by
+masking PHYS_OFFSET with 0xf8000000.
+
+However, on IPQ806x, the first ~20MB of RAM is reserved for the hardware
+network accelerators, and the bootloader removes this section from the
+layout passed from the ATAGS (when used).
+
+For newer bootloader, when DT is used, this is not a problem, we just
+reserve this memory in the device tree. But if the bootloader doesn't
+have DT support, then ATAGS have to be used. In this case, the ARM
+decompressor will position the kernel in this low mem, which will not be
+in the RAM section mapped by the bootloader, which means the kernel will
+freeze in the middle of the boot process trying to map the memory.
+
+As a work around, this patch allows disabling AUTO_ZRELADDR when
+ARCH_QCOM is selected. It makes the zImage usage possible on bootloaders
+which don't support device-tree, which is the case on certain early
+IPQ806x based designs.
+
+Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>
+---
+ arch/arm/Kconfig                 | 2 +-
+ arch/arm/Makefile                | 2 ++
+ arch/arm/mach-qcom/Makefile.boot | 1 +
+ 3 files changed, 4 insertions(+), 1 deletion(-)
+ create mode 100644 arch/arm/mach-qcom/Makefile.boot
+
+diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
+index 89c4b5c..4583ea5 100644
+--- a/arch/arm/Kconfig
++++ b/arch/arm/Kconfig
+@@ -311,7 +311,7 @@ config ARCH_MULTIPLATFORM
+ 	select ARCH_WANT_OPTIONAL_GPIOLIB
+ 	select ARM_HAS_SG_CHAIN
+ 	select ARM_PATCH_PHYS_VIRT
+-	select AUTO_ZRELADDR
++	select AUTO_ZRELADDR if !ARCH_QCOM
+ 	select CLKSRC_OF
+ 	select COMMON_CLK
+ 	select GENERIC_CLOCKEVENTS
+diff --git a/arch/arm/Makefile b/arch/arm/Makefile
+index 7453352..5d6f8ac 100644
+--- a/arch/arm/Makefile
++++ b/arch/arm/Makefile
+@@ -240,9 +240,11 @@ MACHINE  := arch/arm/mach-$(word 1,$(machine-y))/
+ else
+ MACHINE  :=
+ endif
++ifeq ($(CONFIG_ARCH_QCOM),)
+ ifeq ($(CONFIG_ARCH_MULTIPLATFORM),y)
+ MACHINE  :=
+ endif
++endif
+ 
+ machdirs := $(patsubst %,arch/arm/mach-%/,$(machine-y))
+ platdirs := $(patsubst %,arch/arm/plat-%/,$(sort $(plat-y)))
+diff --git a/arch/arm/mach-qcom/Makefile.boot b/arch/arm/mach-qcom/Makefile.boot
+new file mode 100644
+index 0000000..67a6d5a
+--- /dev/null
++++ b/arch/arm/mach-qcom/Makefile.boot
+@@ -0,0 +1 @@
++zreladdr-y+= 0x42208000
+-- 
+1.9.1
+