[U-Boot] [RFC] Reserve ATF memory on Marvell Armdada 3700/7K/8K

[Mark Kettenis]

Currently U-Boot doesn't make any effort to reserve the memory used by
ARM Trusted Firmware on these platforms.  The result is that the
memory is listed as available in the EFI memory map.  And as soon as a
loaded kernel tries to use this memory things explode.  I've seen this
with the OpenBSD kernel.  But I totally expect a Linux kernel to
suffer the same fate.

I'm currently using the diff below, but it is not entirely clear to me
if arch_early_init_r() is the appropriate place to do this.  I'm also
wondering whether the block should also be marked as reserved in the
FDT using fdt_add_mem_rsv().  If the latter is required this probably
needs to be done by ft_board_setup() or ft_system_setup().

The address and size of the region have been taken from Marvell's ATF
fork at

  https://github.com/MarvellEmbeddedProcessors/atf-marvell

The memory layout is defined in

  plat/marvell/a8k/common/include/platform_def.h

where there are lots of defines and a diagram that attempt to describe
the memory.  It is not entirely obvious to me what part needs to be
reserved.  But 0x0400000-0x04200000 works.




diff --git a/arch/arm/mach-mvebu/arm64-common.c b/arch/arm/mach-mvebu/arm64-common.c
index 3c84043a2c..895cd2852f 100644
--- a/arch/arm/mach-mvebu/arm64-common.c
+++ b/arch/arm/mach-mvebu/arm64-common.c
@@ -95,5 +95,11 @@ int arch_early_init_r(void)
 	pci_init();
 #endif
 
+#ifdef CONFIG_EFI_LOADER
+	/* Reserve trusted SRAM section */
+	efi_add_memory_map(0x04000000, 0x00200000 >> EFI_PAGE_SHIFT,
+			   EFI_RESERVED_MEMORY_TYPE, false);
+#endif
+
 	return 0;
 }