arm: Add devicetree fixup machine function

Commit 1c2f87c22566cd057bc8cde10c37ae9da1a1bb76
(ARM: 8025/1: Get rid of meminfo) dropped the upper bound on
the number of memory banks that can be added as there was no
technical need in the kernel. It turns out though, some bootloaders
(specifically the arndale-octa exynos boards) may pass invalid memory
information and rely on the kernel to not parse this data. This is a
bug in the bootloader but we still need to work around this.
Work around this by introducing a dt_fixup function. This function
gets called before the flattened devicetree is scanned for memory
and the like. In this fixup function for exynos, limit the maximum
number of memory regions in the devicetree.

Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Tested-by: Andreas Färber <afaerber@suse.de>
[glikely: Added a comment and fixed up function name]
Signed-off-by: Grant Likely <grant.likely@linaro.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
index e94a157ddff1..11c54de9f8cf 100644
--- a/arch/arm/kernel/devtree.c
+++ b/arch/arm/kernel/devtree.c
@@ -212,7 +212,7 @@ const struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
         mdesc_best = &__mach_desc_GENERIC_DT;
 #endif
 
-        if (!dt_phys || !early_init_dt_scan(phys_to_virt(dt_phys)))
+        if (!dt_phys || !early_init_dt_verify(phys_to_virt(dt_phys)))
                 return NULL;
 
         mdesc = of_flat_dt_match_machine(mdesc_best, arch_get_next_mach);
@@ -237,6 +237,12 @@ const struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
                 dump_machine_table(); /* does not return */
         }
 
+        /* We really don't want to do this, but sometimes firmware provides buggy data */
+        if (mdesc->dt_fixup)
+                mdesc->dt_fixup();
+
+        early_init_dt_scan_nodes();
+
         /* Change machine number to match the mdesc we're using */
         __machine_arch_type = mdesc->nr;