a8k: Implement platform specific power off

Implements a way to add platform specific power off code to a
Marvell Armada 8K platform.

Marvell Armada 8K boards can now add a board/system_power.c file
that contains a system_power_off() function.
This function can now send a command to a power management MCU or
other board periferals before shutting the board down.

Signed-off-by: Luka Kovacic <luka.kovacic@sartura.hr>
Cc: Luka Perkov <luka.perkov@sartura.hr>
Change-Id: Iaba20bc2f603195679c54ad12c0c18962dd8e3db
---
I am working on a device that will be ported later, which has a
custom power management MCU that handles LEDs, board power and fans
and requires this separation.

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

@@ -124,5 +124,6 @@ int marvell_get_iob_memory_map(struct addr_map_win **win,
 			       uint32_t *size, uintptr_t base);
 int marvell_get_ccu_memory_map(int ap_idx, struct addr_map_win **win,
 			       uint32_t *size);
+int system_power_off(void);
 
 #endif /* ARMADA_COMMON_H */

plat/marvell/a8k/common/a8k_common.mk

@@ -37,6 +37,13 @@ DOIMAGETOOL		?=	${DOIMAGEPATH}/doimage
 ROM_BIN_EXT ?= $(BUILD_PLAT)/ble.bin
 DOIMAGE_FLAGS	+= -b $(ROM_BIN_EXT) $(NAND_DOIMAGE_FLAGS) $(DOIMAGE_SEC_FLAGS)
 
+# Check whether to build system_power.c for the platform
+ifneq ("$(wildcard $(PLAT_FAMILY_BASE)/$(PLAT)/board/system_power.c)","")
+SYSTEM_POWER_SUPPORT = 1
+else
+SYSTEM_POWER_SUPPORT = 0
+endif
+
 # This define specifies DDR type for BLE
 $(eval $(call add_define,CONFIG_DDR4))
 
@@ -82,6 +89,10 @@ MARVELL_DRV		:= 	$(MARVELL_DRV_BASE)/io_win.c	\
 
 BL31_PORTING_SOURCES	:=	$(PLAT_FAMILY_BASE)/$(PLAT)/board/marvell_plat_config.c
 
+ifeq ($(SYSTEM_POWER_SUPPORT),1)
+BL31_PORTING_SOURCES	+=	$(PLAT_FAMILY_BASE)/$(PLAT)/board/system_power.c
+endif
+
 BL31_SOURCES		+=	lib/cpus/aarch64/cortex_a72.S		       \
 				$(PLAT_COMMON_BASE)/aarch64/plat_helpers.S     \
 				$(PLAT_COMMON_BASE)/aarch64/plat_arch_config.c \

plat/marvell/a8k/common/plat_pm.c

@@ -792,8 +792,20 @@ __dead2 a8k_pwr_domain_pwr_down_wfi(const psci_power_state_t *target_state)
  * A8K handlers to shutdown/reboot the system
  *****************************************************************************
  */
+
+/* Set a weak stub for platforms that don't configure system power off */
+#pragma weak system_power_off
+int system_power_off(void)
+{
+	return 0;
+}
+
 static void __dead2 a8k_system_off(void)
 {
+	/* Call the platform specific system power off function */
+	system_power_off();
+
+	/* board doesn't have a system off implementation */
 	ERROR("%s:  needs to be implemented\n", __func__);
 	panic();
 }