TF-A Porting Guide
=================

This section describes how to port TF-A to a customer board, assuming that the SoC being used is already supported
in TF-A.


Source Code Structure
---------------------
- The customer platform specific code shall reside under "plat/marvell/<soc family>/<soc>_cust"
	(e.g. 'plat/marvell/a8k/a7040_cust').
- The platform name for build purposes is called "<soc>_cust" (e.g. a7040_cust).
- The build system will reuse all files from within the soc directory, and take only the porting
  files from the customer platform directory.

Files that require porting are located at "plat/marvell/<soc family>/<soc>_cust" directory.


Armada-70x0/Armada-80x0 Porting
-------------------------------

  - SoC Physical Address Map (marvell_plat_config.c):
	- This file describes the SoC physical memory mapping to be used for the CCU, IOWIN, AXI-MBUS and IOB
	  address decode units (Refer to the functional spec for more details).
	- In most cases, using the default address decode windows should work OK.
	- In cases where a special physical address map is needed (e.g. Special size for PCIe MEM windows,
	  large memory mapped SPI flash...), then porting of the SoC memory map is required.
	- Note: For a detailed information on how CCU, IOWIN, AXI-MBUS & IOB work, please refer to the SoC functional spec,
	  and under "docs/marvell/misc/mvebu-[ccu/iob/amb/io-win].txt" files.

  - boot loader recovery (marvell_plat_config.c):
	- Background:
		boot rom can skip the current image and choose to boot from next position if a specific value
		(0xDEADB002) is returned by the ble main function. This feature is used for boot loader recovery
		by booting from a valid flash-image saved in next position on flash (e.g. address 2M in SPI flash).

		Supported options to implement the skip request are:
			- GPIO
			- I2C
			- User defined

	- Porting:
		Under marvell_plat_config.c, implement struct skip_image that includes specific board parameters.
		.. warning:: to disable this feature make sure the struct skip_image is not implemented.

	- Example:
		In A7040-DB specific implementation (plat/marvell/a8k/a70x0/board/marvell_plat_config.c),
		the image skip is implemented using GPIO: mpp 33 (SW5).

		Before resetting the board make sure there is a valid image on the next flash address:
			-tftp [valid address] flash-image.bin
			-sf update [valid address] 0x2000000 [size]

		Press reset and keep pressing the button connected to the chosen GPIO pin. A skip image request
		message is printed on the screen and boot rom boots from the saved image at the next position.

  - DDR Porting (dram_port.c):
	- This file defines the dram topology and parameters of the target board.
	- The DDR code is part of the BLE component, which is an extension of ARM Trusted Firmware (TF-A).
	- The DDR driver called mv_ddr is released separately apart from TF-A sources.
	- The BLE and consequently, the DDR init code is executed at the early stage of the boot process.
	- Each supported platform of the TF-A has its own DDR porting file called dram_port.c located at
	  ``atf/plat/marvell/a8k/<platform>/board`` directory.
	- Please refer to '<path_to_mv_ddr_sources>/doc/porting_guide.txt' for detailed porting description.
	- The build target directory is "build/<platform>/release/ble".