arch/arm64: Pass cbmem_top to ramstage via calling argument

This solution is very generic and can in principle be implemented on
all arch/soc. Currently the old infrastructure to pass on information
from romstage to ramstage is left in place and will be removed in a
follow-up commit.

Nvidia Tegra will be handled in a separate patch because it has a
custom ramstage entry.

Instead trying to figure out which files can be removed from stages
and which cbmem_top implementations need with preprocessor, rename all
cbmem_top implementation to cbmem_top_romstage.

Mechanisms set in place to pass on information from rom- to ram-stage
will be replaced in a followup commit.

Change-Id: I86cdc5c2fac76797732a3a3398f50c4d1ff6647a
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36275
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/arch/arm64/Kconfig

@@ -17,6 +17,7 @@ config ARCH_ROMSTAGE_ARM64
 config ARCH_RAMSTAGE_ARM64
 	bool
 	select ARCH_ARM64
+	select RAMSTAGE_CBMEM_TOP_ARG if !SOC_NVIDIA_TEGRA210
 
 source src/arch/arm64/armv8/Kconfig
 

src/arch/arm64/boot.c

@@ -11,6 +11,7 @@
  * GNU General Public License for more details.
  */
 
+#include <cbmem.h>
 #include <arch/cache.h>
 #include <arch/lib_helpers.h>
 #include <arch/stages.h>
@@ -48,7 +49,10 @@ void arch_prog_run(struct prog *prog)
 }
 
 /* Generic stage entry point. Can be overridden by board/SoC if needed. */
-__weak void stage_entry(void)
+__weak void stage_entry(uintptr_t stage_arg)
 {
+	if (!ENV_ROMSTAGE_OR_BEFORE)
+		_cbmem_top_ptr = stage_arg;
+
 	main();
 }

src/arch/arm64/include/arch/stages.h

@@ -17,7 +17,7 @@
 #include <stdint.h>
 #include <main_decl.h>
 
-void stage_entry(void);
+void stage_entry(uintptr_t stage_arg);
 
 /* This function is the romstage platform entry point, and should contain all
    chipset and mainboard setup until DRAM is initialized and accessible. */