plat/arm/sgi: introduce number of chips macro

Introduce macro 'CSS_SGI_CHIP_COUNT' to allow Arm CSS platforms with
multi-chip support to define number of chiplets on the platform. By
default, this flag is set to 1 and does not affect the existing single
chip platforms.

For multi-chip platforms, override the default value of
CSS_SGI_CHIP_COUNT with the number of chiplets supported on the
platform. As an example, the command below sets the number of chiplets
to two on the RD-N1-Edge multi-chip platform:

export CROSS_COMPILE=<path-to-cross-compiler>
make PLAT=rdn1edge CSS_SGI_CHIP_COUNT=2 ARCH=aarch64 all

Change-Id: If364dc36bd34b30cc356f74b3e97633933e6c8ee
Signed-off-by: Vijayenthiran Subramaniam <vijayenthiran.subramaniam@arm.com>

docs/plat/arm/arm-build-options.rst

@@ -114,6 +114,11 @@ Arm CSS Platform-Specific Build Options
    management operations and for SCP RAM Firmware transfer. If this option
    is set to 1, then SCMI/SDS drivers will be used. Default is 0.
 
+ - ``CSS_SGI_CHIP_COUNT``: Configures the number of chips on a SGI/RD platform
+   which supports multi-chip operation. If ``CSS_SGI_CHIP_COUNT`` is set to any
+   valid value greater than 1, the platform code performs required configuration
+   to support multi-chip operation.
+
 --------------
 
 *Copyright (c) 2019-2020, Arm Limited. All rights reserved.*

plat/arm/board/rde1edge/platform.mk

@@ -47,4 +47,9 @@ NT_FW_CONFIG		:=	${BUILD_PLAT}/fdts/${PLAT}_nt_fw_config.dtb
 # Add the NT_FW_CONFIG to FIP and specify the same to certtool
 $(eval $(call TOOL_ADD_PAYLOAD,${NT_FW_CONFIG},--nt-fw-config))
 
+ifneq ($(CSS_SGI_CHIP_COUNT),1)
+ $(error  "Chip count for RDE1Edge should be 1, currently set to \
+   ${CSS_SGI_CHIP_COUNT}.")
+endif
+
 override CTX_INCLUDE_AARCH32_REGS	:= 0

plat/arm/board/rdn1edge/platform.mk

@@ -47,4 +47,9 @@ NT_FW_CONFIG		:=	${BUILD_PLAT}/fdts/${PLAT}_nt_fw_config.dtb
 # Add the NT_FW_CONFIG to FIP and specify the same to certtool
 $(eval $(call TOOL_ADD_PAYLOAD,${NT_FW_CONFIG},--nt-fw-config))
 
+ifneq ($(CSS_SGI_CHIP_COUNT),1)
+ $(error  "Chip count for RDN1Edge should be 1, currently set to \
+   ${CSS_SGI_CHIP_COUNT}.")
+endif
+
 override CTX_INCLUDE_AARCH32_REGS	:= 0

plat/arm/board/sgi575/platform.mk

@@ -46,3 +46,8 @@ NT_FW_CONFIG		:=	${BUILD_PLAT}/fdts/${PLAT}_nt_fw_config.dtb
 
 # Add the NT_FW_CONFIG to FIP and specify the same to certtool
 $(eval $(call TOOL_ADD_PAYLOAD,${NT_FW_CONFIG},--nt-fw-config))
+
+ifneq ($(CSS_SGI_CHIP_COUNT),1)
+ $(error  "Chip count for SGI575 should be 1, currently set to \
+   ${CSS_SGI_CHIP_COUNT}.")
+endif

plat/arm/css/sgi/sgi-common.mk

@@ -16,6 +16,8 @@ EL3_EXCEPTION_HANDLING		:=	0
 
 HANDLE_EA_EL3_FIRST		:=	0
 
+CSS_SGI_CHIP_COUNT		:=	1
+
 INTERCONNECT_SOURCES	:=	${CSS_ENT_BASE}/sgi_interconnect.c
 
 PLAT_INCLUDES		+=	-I${CSS_ENT_BASE}/include
@@ -52,6 +54,8 @@ endif
 
 $(eval $(call add_define,SGI_PLAT))
 
+$(eval $(call add_define,CSS_SGI_CHIP_COUNT))
+
 override CSS_LOAD_SCP_IMAGES	:=	0
 override NEED_BL2U		:=	no
 override ARM_BL31_IN_DRAM	:=	1