docs: Add Marvell build and porting documents
Change-Id: I341440701b7e5e3555e604dd9d0a356795e6c4fb
Signed-off-by: Hanna Hawa <hannah@marvell.com>
Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
diff --git a/docs/marvell/porting.txt b/docs/marvell/porting.txt
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+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".
+