# Details for the platform/ext folder This folder has code that has been imported from other projects. This means the files in this folder and subfolders have Apache 2.0 license which is different to BSD 3.0 license applied to the parent TF-M project. `NOTE` This folder is strictly Apache 2.0 with the exception of cmake files. Maintainers should be consulted if this needs to be revisited. ## Sub-folders ### cmsis This folder contains core and compiler specific header files imported from the CMSIS_5 project. ### common This folder contains stdout redirection to UART, a temporary memory mapped flash implementation for the bootloader and tfm_mbedtls_config.h for all the targets. ### drivers This folder contains the headers with CMSIS compliant driver definitions that that TF-M project expects a target to provide. #### target_cfg.h This file is expected to define the following macros respectively. - `TFM_DRIVER_STDIO` This macro should expand to a structure of type `ARM_DRIVER_USART`. TFM redirects its standard input and output to this instance of USART. - `NS_DRIVER_STDIO` This macro should expand to a structure of type `ARM_DRIVER_USART`. Non-Secure application redirects its standard input and output to this instance of USART. ### target This folder contains the files for individual target. #### Flash layout header file Target must provide a header file, called flash_layout.h, which defines the information explained in the follow subsections. The defines must be named as they are in the subsections. ##### BL2 bootloader The BL2 bootloader requires the following definitions: - `FLASH_BASE_ADDRESS` Defines the first valid address in the flash. - `FLASH_AREA_BL2_OFFSET` Defines the offset from the flash base address where the BL2 - MCUBOOT area starts. - `FLASH_AREA_BL2_SIZE` Defines the size of the BL2 area. - `FLASH_AREA_IMAGE_0_OFFSET` Defines the offset from the flash base address where the image 0 area starts, which hosts the active firmware image. - `FLASH_AREA_IMAGE_0_SIZE` Defines the size of the image 0 area. - `FLASH_AREA_IMAGE_1_OFFSET` Defines the offset from the flash base address where the image 1 area starts, which is a placeholder for new firmware images. - `FLASH_AREA_IMAGE_1_SIZE` Defines the size of the image 1 area. - `FLASH_AREA_IMAGE_SCRATCH_OFFSET` Defines the offset from the flash base address where the scratch area starts, which is used during image swapping. - `FLASH_AREA_IMAGE_SCRATCH_SIZE` Defines the size of the scratch area. The minimal size must be as the biggest sector size in the flash. - `FLASH_DEV_NAME` Specifies the flash device used by BL2 and SST. ##### Assemble tool The assemble.py tools is used to concatenate secure and non-secure binary to a single binary blob. It requires the following definitions: - `SECURE_IMAGE_OFFSET` Defines the offset from the single binary blob base address, where the secure image starts. - `SECURE_IMAGE_MAX_SIZE` Defines the maximum size of the secure image area. - `NON_SECURE_IMAGE_OFFSET` Defines the offset from the single binary blob base address, where the non-secure image starts. - `NON_SECURE_IMAGE_MAX_SIZE` Defines the maximum size of the non-secure image area. ##### Secure Storage (SST) Service definitions The SST service requires the following definitions: - `SST_FLASH_AREA_ADDR` Defines the flash area address where the secure store area starts. - `SST_SECTOR_SIZE` Defines the size of the flash sectors. - `SST_NBR_OF_SECTORS` Defines the number of sectors available for the secure area. - `FLASH_DEV_NAME` Specifies the flash device used by BL2 and SST. - `SST_FLASH_PROGRAM_UNIT` Defines the smallest flash programmable unit in bytes. - `SST_MAX_ASSET_SIZE` Defines the maximum asset size to be stored in the SST area. - `SST_NUM_ASSETS` Defines the maximum number of assets to be stored in the SST area. **Note**: The sectors must be consecutive. ## Expose target support for HW components Services may require HW components to be supported by the target to enable some features (e.g. SST service with rollback protection, etc). The following definitions need to be set in the .cmake file if the target has the following HW components: - `TARGET_NV_COUNTERS_ENABLE` Specifies that the target has non-volatile (NV) counters. -------------- *Copyright (c) 2017-2019, Arm Limited. All rights reserved.*