Details for the platform folder

Interfacing with TF-M

platform/ext/target/tfm_peripherals_def.h

This file should enumerate the hardware peripherals that are available for TF-M on the platform. The name of the peripheral used by a service is set in its manifest file. The platform have to provide a macro for each of the provided peripherals, that is substituted to a pointer to type struct platform_data_t. The memory that the pointer points to is allocated by the platform code. The pointer gets stored in the partitions database in SPM, and it is provided to the SPM HAL functions.

Peripherals currently used by the services in TF-M

  • TFM_PERIPHERAL_UART1- UART1

Note

If a platform doesn’t support a peripheral, that is used by a service, then the service cannot be used on the given platform. Using a peripheral in TF-M that is not supported by the platform results in compile error.

platform/include/tfm_spm_hal.h

This file contains the declarations of functions that a platform implementation has to provide for TF-M’s SPM. For details see the comments in the file.

secure_fw/core/include/tfm_platform_core_api.h

This file contains declarations of functions that can be or have to be called from platform implementations. For details see the comments in the file.

platform/include/tfm_platform_system.h

This file contains the declarations of functions that a platform implementation has to provide for TF-M’s Platform Service. For details see docs/user_guides/services/tfm_platform_integration_guide.rst

System Startup

Before calling main(), platform startup code should initialise all system clocks, perform runtime initialisation and other steps such as setting the vector table. Configuration of the following features is optional as TF-M architecture code will check and initialise them:

  • The Security Extension.

  • The Floating-point Extension.

Debug authentication settings

A platform may provide the option to configure debug authentication. TF-M core calls the HAL function enum tfm_hal_status_t tfm_hal_platform_init(void) in which debug authentication is configured based on the following defines:

  • DAUTH_NONE: Debugging the system is not enabled.

  • DAUTH_NS_ONLY: Invasive and non invasive debugging of non-secure code is enabled.

  • DAUTH_FULL: Invasive and non-invasive debugging of non-secure and secure code is enabled.

  • DAUTH_CHIP_DEFAULT: The debug authentication options are used that are set by the chip vendor.

The desired debug authentication configuration can be selected by setting one of the options above to the cmake command with the -DDEBUG_AUTHENTICATION=”<define>” option. The default value of DEBUG_AUTHENTICATION is DAUTH_CHIP_DEFAULT.

Note

enum tfm_hal_status_t tfm_hal_platform_init(void) is called during the TF-M core initialisation phase, before initialising secure partition. This means that BL2 runs with the chip default setting.

Sub-folders

include

This folder contains the interfaces that TF-M expects every target to provide. The code in this folder is created as a part of the TF-M project therefore it adheres to the BSD 3.0 license.

ext

This folder contains code that has been imported from other projects so it may have licenses other than the BSD 3.0 used by the TF-M project.

Please see the Details for the platform/ext folder for details.


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