lib: Hook up libhwbase in romstage

It's hidden behind the configuration option `CONFIG_ROMSTAGE_LIBHWBASE'.

This also adds some glue code to use the coreboot console for debug
output and our monotonic timer framework as timer backend.

Running Ada code in romstage and more particular libhwbase brings a few
challenges as global initialized variables are not supported in
Cache-As-Ram mode.

1. The libhwbase dynamic mmio driver implementation makes the Gnat
   compiler generate some global initialized variables.

   For this reason, when compiled for romstage or for romstage and
   ramstage the static mmio driver is enforced (`HWBASE_STATIC_MMIO').

2. The Gnat compiler generates elaboration functions to initialize
   program data at runtime. These elaboration functions are called by
   the romstage_adainit() function.

   The data references symbols suffixed by `_E'. Even though these
   symbols, at compilation time, do not contain any data and are
   filled with zeros, the Gnat compiler installs them in the .data
   section.

   Since these symbols are actually filled with zeros, it is safe to
   install them in the .bss section.

   cf. https://docs.adacore.com/gnat_ugn-docs/html/gnat_ugn/gnat_ugn/elaboration_order_handling_in_gnat.html#elaboration-code

This patch requires the libhwbase
https://review.coreboot.org/c/libhwbase/+/69854 CL.

BUG=b:252792591
BRANCH=firmware-brya-14505.B
TEST=libhwbae compiles for romstage and loads successfully

Change-Id: I670249d33506e886a683e55d1589cb2bf9b16aa3
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70275
Reviewed-by: Boris Mittelberg <bmbm@google.com>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-by: Tarun Tuli <taruntuli@google.com>
Reviewed-by: Zhixing Ma <zhixing.ma@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/arch/x86/car.ld

@@ -67,6 +67,12 @@
 	*(.bss.*)
 	*(.sbss)
 	*(.sbss.*)
+	/* '*_E' GNAT generated global variables actually are un-initialized
+	 * (filled with zeros) variables which are initialized at
+	 * runtime. Therefore, they can be placed in the _bss region. */
+#if CONFIG(ROMSTAGE_LIBHWBASE)
+	*(.data.hw__*_E)
+#endif
 	. = ALIGN(ARCH_POINTER_ALIGN_SIZE);
 	_ebss = .;
 	RECORD_SIZE(bss)

src/console/Makefile.inc

@@ -5,6 +5,8 @@ ramstage-y += die.c
 ifeq ($(CONFIG_HWBASE_DEBUG_CB),y)
 ramstage-$(CONFIG_RAMSTAGE_LIBHWBASE) += hw-debug_sink.ads
 ramstage-$(CONFIG_RAMSTAGE_LIBHWBASE) += hw-debug_sink.adb
+romstage-$(CONFIG_ROMSTAGE_LIBHWBASE) += hw-debug_sink.ads
+romstage-$(CONFIG_ROMSTAGE_LIBHWBASE) += hw-debug_sink.adb
 endif
 
 smm-$(CONFIG_DEBUG_SMI) += init.c console.c vtxprintf.c printk.c

src/lib/Kconfig

@@ -21,6 +21,12 @@ config RAMSTAGE_LIBHWBASE
 	help
 	  Selected by features that require `libhwbase` in ramstage.
 
+config ROMSTAGE_LIBHWBASE
+	bool
+	select ROMSTAGE_ADA
+	help
+	  Selected by features that require `libhwbase` in romstage.
+
 config FLATTENED_DEVICE_TREE
 	bool
 	help
@@ -68,11 +74,22 @@ config SPD_CACHE_FMAP_NAME
 	help
 	  Name of the FMAP region created in the default FMAP to cache SPD data.
 
-if RAMSTAGE_LIBHWBASE
+if RAMSTAGE_LIBHWBASE && !ROMSTAGE_LIBHWBASE
 
 config HWBASE_DYNAMIC_MMIO
 	def_bool y
 
+endif
+
+if ROMSTAGE_LIBHWBASE
+
+config HWBASE_STATIC_MMIO
+	def_bool y
+
+endif
+
+if RAMSTAGE_LIBHWBASE || ROMSTAGE_LIBHWBASE
+
 config HWBASE_DEFAULT_MMCONF
 	hex
 	default ECAM_MMCONF_BASE_ADDRESS

src/lib/Makefile.inc

@@ -342,28 +342,34 @@ $(obj)/%.elf.rmod: $(obj)/%.elf | $(RMODTOOL)
 romstage-$(CONFIG_ROMSTAGE_ADA) += cb.ads
 ramstage-$(CONFIG_RAMSTAGE_ADA) += cb.ads
 
-ifeq ($(CONFIG_RAMSTAGE_LIBHWBASE),y)
+ifneq (,$(filter y, $(CONFIG_RAMSTAGE_LIBHWBASE) $(CONFIG_ROMSTAGE_LIBHWBASE)))
 
 to-ada-hex = $(eval $(1) := 16\\\#$(patsubst 0x%,%,$($(1)))\\\#)
 
 $(call to-ada-hex,CONFIG_HWBASE_DEFAULT_MMCONF)
 
+libhwbase-stages = $(foreach stage, romstage ramstage, \
+	$(if $(filter y,$(CONFIG_$(call toupper,$(stage))_LIBHWBASE)),$(stage)))
+
 $(call add-special-class,hw)
-hw-handler = $(eval ramstage-srcs += $$(addprefix $(1),$(2)))
+hw-handler +=$(foreach stage, $(libhwbase-stages), \
+	$(eval $(stage)-srcs += $$(addprefix $(1),$(2))))
 
 $(call add-special-class,hw-gen)
 hw-gen-handler = \
 	$(eval additional-dirs += $(dir $(2))) \
-	$(eval ramstage-srcs += $(2)) \
-	$(eval ramstage-ads-deps += $(2)) \
-	$(eval ramstage-adb-deps += $(2)) \
+	$(foreach stage, $(libhwbase-stages), \
+		$(eval $(stage)-srcs += $(2)) \
+		$(eval $(stage)-ads-deps += $(2)) \
+		$(eval $(stage)-adb-deps += $(2))) \
 	$(eval $(2): $(obj)/config.h)
 
 subdirs-y += ../../3rdparty/libhwbase
 
-ramstage-$(CONFIG_HAVE_MONOTONIC_TIMER) += hw-time-timer.adb
+$(foreach stage,$(libhwbase-stages), \
+	$(eval $(stage)-$(CONFIG_HAVE_MONOTONIC_TIMER) += hw-time-timer.adb))
 
-endif # CONFIG_RAMSTAGE_LIBHWBASE
+endif # CONFIG_ROMSTAGE_LIBHWBASE || CONFIG_RAMSTAGE_LIBHWBASE
 
 romstage-y += spd_bin.c