drivers/intel/fsp2_0: Use coreboot postcar with FSP-T

Allow platforms to use the coreboot postcar code instead of calling
into FSP-M TempRamExit API.

There are several reasons to do this:
- Tearing down CAR is easy.
- Allows having control over MTRR's and caching in general.
- The MTRR's set up in postcar be it by coreboot or FSP-M are
  overwritten later on during CPU init so it does not matter.
- Avoids having to find a CBFS file before cbmem is up (this
  causes problems with cbfs_mcache)

Change-Id: I6cf10c7580f3183bfee1cd3c827901cbcf695db7
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48466
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/drivers/intel/fsp2_0/Kconfig

@@ -126,6 +126,13 @@ config FSP_T_RESERVED_SIZE
 	  defined in the FSP specification but in the SOC integration
 	  guides.
 
+config NO_FSP_TEMP_RAM_EXIT
+	bool
+	depends on FSP_CAR
+	help
+	  Select this on a platform where you want to use FSP-T but use
+	  coreboot code to tear down CAR.
+
 config FSP_M_XIP
 	bool
 	default n

src/drivers/intel/fsp2_0/Makefile.inc

@@ -29,7 +29,9 @@ ramstage-$(CONFIG_DISPLAY_UPD_DATA) += upd_display.c
 ramstage-y += util.c
 ramstage-$(CONFIG_MMA) += mma_core.c
 
+ifneq ($(CONFIG_NO_FSP_TEMP_RAM_EXIT),y)
 postcar-$(CONFIG_FSP_CAR) += temp_ram_exit.c
+endif
 postcar-$(CONFIG_FSP_CAR) += util.c
 postcar-$(CONFIG_DISPLAY_FSP_HEADER) += header_display.c
 postcar-y += hand_off_block.c

src/soc/intel/common/block/cpu/Makefile.inc

@@ -1,6 +1,10 @@
 ifeq ($(CONFIG_FSP_CAR),y)
 bootblock-$(CONFIG_SOC_INTEL_COMMON_BLOCK_CPU)+= car/cache_as_ram_fsp.S
+ifeq ($(CONFIG_NO_FSP_TEMP_RAM_EXIT),y)
+postcar-$(CONFIG_SOC_INTEL_COMMON_BLOCK_CPU) += car/exit_car.S
+else
 postcar-$(CONFIG_SOC_INTEL_COMMON_BLOCK_CPU) += car/exit_car_fsp.S
+endif
 else
 bootblock-$(CONFIG_SOC_INTEL_COMMON_BLOCK_CAR) += car/cache_as_ram.S
 bootblock-$(CONFIG_SOC_INTEL_COMMON_BLOCK_CAR) += ../../../../../cpu/x86/early_reset.S