ARM: introduce atag_offset to replace boot_params

The boot_params member of the mdesc structure is used to provide a
default physical address for the ATAG list.  Since this value is fixed
at compile time and sometimes based on constants such as ARCH_PHYS_OFFSET,
it gets in the way of runtime PHYS_OFFSET and CONFIG_ARM_PATCH_PHYS_VIRT
usage.

Let's introduce atag_offset which should contains only the relative
offset from PHYS_OFFSET instead of an absolute value, in preparation
to move all instance of boot_params over to it.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Tested-by: Petr Štetiar <ynezz@true.cz>
Acked-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 70bca649e925..2737ba3f739c 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -819,6 +819,8 @@ static struct machine_desc * __init setup_machine_tags(unsigned int nr)
 
         if (__atags_pointer)
                 tags = phys_to_virt(__atags_pointer);
+        else if (mdesc->atag_offset)
+                tags = (void *)(PAGE_OFFSET + mdesc->atag_offset);
         else if (mdesc->boot_params) {
 #ifdef CONFIG_MMU
                 /*