docs/porting-guide.rst - next/TF-A/tf-a-tests - TrustedFirmware Git Browser

 Porting Guide
 =============

 Introduction
 ------------

 Please note that this document is incomplete.

 Porting the TF-A Tests to a new platform involves making some mandatory and
 optional modifications for both the cold and warm boot paths. Modifications
 consist of:

 *   Implementing a platform-specific function or variable,
 *   Setting up the execution context in a certain way, or
 *   Defining certain constants (for example #defines).

 The platform-specific functions and variables are all declared in
 ``include/plat/common/platform.h``. The framework provides a default
 implementation of variables and functions to fulfill the optional requirements.
 These implementations are all weakly defined; they are provided to ease the
 porting effort. Each platform port can override them with its own implementation
 if the default implementation is inadequate.

 Platform requirements
 ---------------------

 The TF-A Tests rely on the following features to be present on the platform and
 accessible from Normal World.

 -  Watchdog
 -  Non-Volatile Memory
 -  System Timer

 This also means that a platform port of the TF-A Tests must include software
 drivers for those features.

 Mandatory modifications
 -----------------------

 File : platform_def.h [mandatory]
 `````````````````````````````````

 Each platform must ensure that a header file of this name is in the system
 include path with the following constants defined. This may require updating the
 list of ``PLAT_INCLUDES`` in the ``platform.mk`` file. In the ARM FVP port, this
 file is found in ``plat/arm/board/fvp/include/platform_def.h``.

 -  **#define : PLATFORM_LINKER_FORMAT**

    Defines the linker format used by the platform, for example
    `elf64-littleaarch64` used by the FVP.

 -  **#define : PLATFORM_LINKER_ARCH**

    Defines the processor architecture for the linker by the platform, for
    example `aarch64` used by the FVP.

 -  **#define : PLATFORM_STACK_SIZE**

    Defines the stack memory available to each CPU. This constant is used by
    ``plat/common/aarch64/platform_mp_stack.S``.

 -  **#define : PLATFORM_CLUSTER_COUNT**

    Defines the total number of clusters implemented by the platform in the
    system.

 -  **#define : PLATFORM_CORE_COUNT**

    Defines the total number of CPUs implemented by the platform across all
    clusters in the system.

 -  **#define : PLATFORM_NUM_AFFS**

    Defines the total number of nodes in the affinity hierarchy at all affinity
    levels used by the platform.

 -  **#define : PLATFORM_MAX_AFFLVL**

    Defines the maximum number of affinity levels in the system that the platform
    implements.  ARMv8-A has support for 4 affinity levels. It is likely that
    hardware will implement fewer affinity levels. For example, the Base AEM FVP
    implements two clusters with a configurable number of CPUs.  It reports the
    maximum affinity level as 1.

 -  **#define : PLAT_MAX_SPI_OFFSET_ID**

    Defines the offset of the last Shared Peripheral Interrupt supported by the
    TF-A Tests on this platform. SPI numbers are mapped onto GIC interrupt IDs,
    starting from interrupt ID 32. In other words, this offset ID corresponds to
    the last SPI number, to which 32 must be added to get the corresponding last
    GIC IRQ ID.

    E.g. If ``PLAT_MAX_SPI_OFFSET_ID`` is 10, this means that IRQ #42 is the last
    SPI.

 -  **#define : PLAT_LOCAL_PSTATE_WIDTH**

    Defines the bit-field width of the local state in State-ID field of the
    power-state parameter. This macro will be used to compose the State-ID field
    given the local power state at different affinity levels.

 -  **#define : PLAT_MAX_PWR_STATES_PER_LVL**

    Defines the maximum number of power states at a power domain level for the
    platform. This macro will be used by the ``PSCI_STAT_COUNT/RESIDENCY`` tests
    to determine the size of the array to allocate for storing the statistics.

 -  **#define : TFTF_BASE**

    Defines the base address of the TFTF binary in DRAM. Used by the linker
    script to link the image at the right address. Must be aligned on a page-size
    boundary.

 -  **#define : IRQ_PCPU_NS_TIMER**

    Defines the IRQ ID of the per-CPU Non-Secure timer of the platform.

 -  **#define : IRQ_CNTPSIRQ1**

    Defines the IRQ ID of the System timer of the platform.

 -  **#define : TFTF_NVM_OFFSET**

    The TFTF needs some Non-Volatile Memory to store persistent data. This
    defines the offset from the beginning of this memory that the TFTF can use.

 -  **#define : TFTF_NVM_SIZE**

    Defines the size of the Non-Volatile Memory allocated for TFTF usage.

 If the platform port uses the ARM Watchdog Module (`SP805`_) peripheral, the
 following constant needs to be defined:

 -  **#define : SP805_WDOG_BASE**

    Defines the base address of the `SP805`_ watchdog peripheral.

 If the platform port uses the IO storage framework, the following constants
 must also be defined:

 -  **#define : MAX_IO_DEVICES**

    Defines the maximum number of registered IO devices. Attempting to register
    more devices than this value using ``io_register_device()`` will fail with
    ``IO_RESOURCES_EXHAUSTED``.

 -  **#define : MAX_IO_HANDLES**

    Defines the maximum number of open IO handles. Attempting to open more IO
    entities than this value using ``io_open()`` will fail with
    ``IO_RESOURCES_EXHAUSTED``.

 If the platform port uses the VExpress NOR flash driver (see
 ``drivers/io/vexpress_nor/``), the following constants must also be defined:

 -  **#define : NOR_FLASH_BLOCK_SIZE**

    Defines the largest block size as seen by the software while writing to NOR
    flash.

 Function : tftf_plat_arch_setup() [mandatory]
 `````````````````````````````````````````````
 ::

     Argument : void
     Return   : void

 This function performs any platform-specific and architectural setup that the
 platform requires.

 In both the ARM FVP and Juno ports, this function configures and enables the
 MMU.

 Function : tftf_early_platform_setup() [mandatory]
 ``````````````````````````````````````````````````

 ::

     Argument : void
     Return   : void

 This function executes with the MMU and data caches disabled. It is only called
 by the primary CPU. It is used to perform platform-specific actions very early
 in the boot.

 In both the ARM FVP and Juno ports, this function configures the console.

 Function : tftf_platform_setup() [mandatory]
 ````````````````````````````````````````````

 ::

     Argument : void
     Return   : void

 This function executes with the MMU and data caches enabled. It is responsible
 for performing any remaining platform-specific setup that can occur after the
 MMU and data cache have been enabled.

 This function is also responsible for initializing the storage abstraction layer
 used to access non-volatile memory for permanent storage of test results. It
 also initialises the GIC and detects the platform topology using
 platform-specific means.

 Function : plat_get_nvm_handle() [mandatory]
 ````````````````````````````````````````````

 ::

     Argument : uintptr_t *
     Return   : void

 It is needed if the platform port uses IO storage framework. This function is
 responsible for getting the pointer to the initialised non-volatile memory
 entity.

 Function : tftf_plat_get_pwr_domain_tree_desc() [mandatory]
 ```````````````````````````````````````````````````````````

 ::

     Argument : void
     Return   : const unsigned char *

 This function returns the platform topology description array in a suitable
 format as expected by TFTF. The size of the array is expected to be
 ``PLATFORM_NUM_AFFS - PLATFORM_CORE_COUNT + 1``. The format used to describe
 this array is :

 1.  The first entry in the array specifies the number of power domains at the
     highest power level implemented in the platform. This caters for platforms
     where the power domain tree does not have a single root node e.g. the FVP
     which has two cluster power domains at the highest level (that is, 1).

 2.  Each subsequent entry corresponds to a power domain and contains the number
     of power domains that are its direct children.

 The array format is the same as the one used by Trusted Firmware-A and more
 details of its description can be found in the Trusted Firmware-A documentation:
 `docs/psci-pd-tree.rst`_.

 Function : tftf_plat_get_mpidr() [mandatory]
 ````````````````````````````````````````````

 ::

     Argument : unsigned int
     Return   : uint64_t

 This function converts a given `core_pos` into a valid MPIDR if the CPU is
 present in the platform. The `core_pos` is a unique number less than the
 ``PLATFORM_CORE_COUNT`` returned by ``platform_get_core_pos()`` for a given
 CPU. This API is used by the topology framework in TFTF to query the presence of
 a CPU and, if present, returns the corresponding MPIDR for it. If the CPU
 referred to by the `core_pos` is absent, then this function returns
 ``INVALID_MPID``.

 Function : plat_get_state_prop() [mandatory]
 ````````````````````````````````````````````

 ::

     Argument : unsigned int
     Return   : const plat_state_prop_t *

 This functions returns the ``plat_state_prop_t`` array for all the valid low
 power states from platform for a specified affinity level and returns ``NULL``
 for an invalid affinity level. The array is expected to be NULL-terminated.
 This function is expected to be used by tests that need to compose the power
 state parameter for use in ``PSCI_CPU_SUSPEND`` API or ``PSCI_STAT/RESIDENCY``
 API.

 Function : plat_fwu_io_setup() [mandatory]
 ``````````````````````````````````````````

 ::

     Argument : void
     Return   : void

 This function initializes the IO system used by the firmware update.

 Function : plat_arm_gic_init() [mandatory]
 ``````````````````````````````````````````

 ::

     Argument : void
     Return   : void

 This function initializes the ARM Generic Interrupt Controller (GIC).

 Function : platform_get_core_pos() [mandatory]
 ``````````````````````````````````````````````

 ::

     Argument : u_register_t
     Return   : unsigned int

 This function returns a linear core ID from a MPID.

 Function : plat_crash_console_init() [mandatory]
 ````````````````````````````````````````````````

 ::

     Argument : void
     Return   : int

 This function initializes a platform-specific console for crash reporting.

 Function : plat_crash_console_putc() [mandatory]
 ````````````````````````````````````````````````

 ::

     Argument : int
     Return   : int

 This function prints a character on the platform-specific crash console.

 Function : plat_crash_console_flush() [mandatory]
 `````````````````````````````````````````````````

 ::

     Argument : void
     Return   : int

 This function waits until all the characters of the platform-specific crash
 console have been actually printed.

 Optional modifications
 ----------------------

 The following are helper functions implemented by the test framework that
 perform common platform-specific tasks. A platform may choose to override these
 definitions.

 Function : platform_get_stack()
 ```````````````````````````````

 ::

     Argument : unsigned long
     Return   : unsigned long

 This function returns the base address of the memory stack that has been
 allocated for the CPU specified by MPIDR. The size of the stack allocated to
 each CPU is specified by the platform defined constant ``PLATFORM_STACK_SIZE``.

 Common implementation of this function is provided in
 ``plat/common/aarch64/platform_mp_stack.S``.

 Function : tftf_platform_end()
 ``````````````````````````````

 ::

     Argument : void
     Return   : void

 This function performs any operation required by the platform to properly finish
 the test session.

 The default implementation sends an EOT (End Of Transmission) character on the
 UART. This can be used to automatically shutdown the FVP models. When running on
 real hardware, the UART output may be parsed by an external tool looking for
 this character and rebooting the platform for example.

 Function : tftf_plat_reset()
 ````````````````````````````

 ::

     Argument : void
     Return   : void

 This function resets the platform.

 The default implementation uses the ARM watchdog peripheral (`SP805`_) to
 generate a watchdog timeout interrupt. This interrupt remains deliberately
 unserviced, which eventually asserts the reset signal.

 Storage abstraction layer
 -------------------------

 In order to improve platform independence and portability a storage abstraction
 layer is used to store test results to non-volatile platform storage.

 Each platform should register devices and their drivers via the Storage layer.
 These drivers then need to be initialized in ``tftf_platform_setup()`` function.

 It is mandatory to implement at least one storage driver. For the FVP and Juno
 platforms the NOR Flash driver is provided as the default means to store test
 results to storage. The storage layer is described in the header file
 ``include/lib/io_storage.h``. The implementation of the common library is in
 ``drivers/io/io_storage.c`` and the driver files are located in ``drivers/io/``.


 Build Flags
 -----------

 -  **PLAT_TESTS_SKIP_LIST**

 This build flag can be defined by the platform to control exclusion of some
 testcases from the default test plan for a platform. If used this needs to
 point to a text file which follows the following criteria:

   -  Contain a list of tests to skip for this platform.

   -  Specify 1 test per line, using the following format:

      ::

        testsuite_name/testcase_name

      where ``testsuite_name`` and ``testcase_name`` are the names that appear in
      the XML tests file.

   -  Alternatively, it is possible to disable a test suite entirely, which will
      disable all test cases part of this test suite. To do so, only specify the
      test suite name, omitting the ``/testcase_name`` part.

 --------------

 *Copyright (c) 2018-2019, Arm Limited. All rights reserved.*

 .. _docs/psci-pd-tree.rst: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/psci-pd-tree.rst
 .. _SP805: https://static.docs.arm.com/ddi0270/b/DDI0270.pdf
	Porting Guide
	=============

	Introduction
	------------

	Please note that this document is incomplete.

	Porting the TF-A Tests to a new platform involves making some mandatory and
	optional modifications for both the cold and warm boot paths. Modifications
	consist of:

	* Implementing a platform-specific function or variable,
	* Setting up the execution context in a certain way, or
	* Defining certain constants (for example #defines).

	The platform-specific functions and variables are all declared in
	``include/plat/common/platform.h``. The framework provides a default
	implementation of variables and functions to fulfill the optional requirements.
	These implementations are all weakly defined; they are provided to ease the
	porting effort. Each platform port can override them with its own implementation
	if the default implementation is inadequate.

	Platform requirements
	---------------------

	The TF-A Tests rely on the following features to be present on the platform and
	accessible from Normal World.

	- Watchdog
	- Non-Volatile Memory
	- System Timer

	This also means that a platform port of the TF-A Tests must include software
	drivers for those features.

	Mandatory modifications
	-----------------------

	File : platform_def.h [mandatory]
	`````````````````````````````````

	Each platform must ensure that a header file of this name is in the system
	include path with the following constants defined. This may require updating the
	list of ``PLAT_INCLUDES`` in the ``platform.mk`` file. In the ARM FVP port, this
	file is found in ``plat/arm/board/fvp/include/platform_def.h``.

	- #define : PLATFORM_LINKER_FORMAT

	Defines the linker format used by the platform, for example
	`elf64-littleaarch64` used by the FVP.

	- #define : PLATFORM_LINKER_ARCH

	Defines the processor architecture for the linker by the platform, for
	example `aarch64` used by the FVP.

	- #define : PLATFORM_STACK_SIZE

	Defines the stack memory available to each CPU. This constant is used by
	``plat/common/aarch64/platform_mp_stack.S``.

	- #define : PLATFORM_CLUSTER_COUNT

	Defines the total number of clusters implemented by the platform in the
	system.

	- #define : PLATFORM_CORE_COUNT

	Defines the total number of CPUs implemented by the platform across all
	clusters in the system.

	- #define : PLATFORM_NUM_AFFS

	Defines the total number of nodes in the affinity hierarchy at all affinity
	levels used by the platform.

	- #define : PLATFORM_MAX_AFFLVL

	Defines the maximum number of affinity levels in the system that the platform
	implements. ARMv8-A has support for 4 affinity levels. It is likely that
	hardware will implement fewer affinity levels. For example, the Base AEM FVP
	implements two clusters with a configurable number of CPUs. It reports the
	maximum affinity level as 1.

	- #define : PLAT_MAX_SPI_OFFSET_ID

	Defines the offset of the last Shared Peripheral Interrupt supported by the
	TF-A Tests on this platform. SPI numbers are mapped onto GIC interrupt IDs,
	starting from interrupt ID 32. In other words, this offset ID corresponds to
	the last SPI number, to which 32 must be added to get the corresponding last
	GIC IRQ ID.

	E.g. If ``PLAT_MAX_SPI_OFFSET_ID`` is 10, this means that IRQ #42 is the last
	SPI.

	- #define : PLAT_LOCAL_PSTATE_WIDTH

	Defines the bit-field width of the local state in State-ID field of the
	power-state parameter. This macro will be used to compose the State-ID field
	given the local power state at different affinity levels.

	- #define : PLAT_MAX_PWR_STATES_PER_LVL

	Defines the maximum number of power states at a power domain level for the
	platform. This macro will be used by the ``PSCI_STAT_COUNT/RESIDENCY`` tests
	to determine the size of the array to allocate for storing the statistics.

	- #define : TFTF_BASE

	Defines the base address of the TFTF binary in DRAM. Used by the linker
	script to link the image at the right address. Must be aligned on a page-size
	boundary.

	- #define : IRQ_PCPU_NS_TIMER

	Defines the IRQ ID of the per-CPU Non-Secure timer of the platform.

	- #define : IRQ_CNTPSIRQ1

	Defines the IRQ ID of the System timer of the platform.

	- #define : TFTF_NVM_OFFSET

	The TFTF needs some Non-Volatile Memory to store persistent data. This
	defines the offset from the beginning of this memory that the TFTF can use.

	- #define : TFTF_NVM_SIZE

	Defines the size of the Non-Volatile Memory allocated for TFTF usage.

	If the platform port uses the ARM Watchdog Module (`SP805`_) peripheral, the
	following constant needs to be defined:

	- #define : SP805_WDOG_BASE

	Defines the base address of the `SP805`_ watchdog peripheral.

	If the platform port uses the IO storage framework, the following constants
	must also be defined:

	- #define : MAX_IO_DEVICES

	Defines the maximum number of registered IO devices. Attempting to register
	more devices than this value using ``io_register_device()`` will fail with
	``IO_RESOURCES_EXHAUSTED``.

	- #define : MAX_IO_HANDLES

	Defines the maximum number of open IO handles. Attempting to open more IO
	entities than this value using ``io_open()`` will fail with
	``IO_RESOURCES_EXHAUSTED``.

	If the platform port uses the VExpress NOR flash driver (see
	``drivers/io/vexpress_nor/``), the following constants must also be defined:

	- #define : NOR_FLASH_BLOCK_SIZE

	Defines the largest block size as seen by the software while writing to NOR
	flash.

	Function : tftf_plat_arch_setup() [mandatory]
	`````````````````````````````````````````````
	::

	Argument : void
	Return : void

	This function performs any platform-specific and architectural setup that the
	platform requires.

	In both the ARM FVP and Juno ports, this function configures and enables the
	MMU.

	Function : tftf_early_platform_setup() [mandatory]
	``````````````````````````````````````````````````

	::

	Argument : void
	Return : void

	This function executes with the MMU and data caches disabled. It is only called
	by the primary CPU. It is used to perform platform-specific actions very early
	in the boot.

	In both the ARM FVP and Juno ports, this function configures the console.

	Function : tftf_platform_setup() [mandatory]
	````````````````````````````````````````````

	::

	Argument : void
	Return : void

	This function executes with the MMU and data caches enabled. It is responsible
	for performing any remaining platform-specific setup that can occur after the
	MMU and data cache have been enabled.

	This function is also responsible for initializing the storage abstraction layer
	used to access non-volatile memory for permanent storage of test results. It
	also initialises the GIC and detects the platform topology using
	platform-specific means.

	Function : plat_get_nvm_handle() [mandatory]
	````````````````````````````````````````````

	::

	Argument : uintptr_t *
	Return : void

	It is needed if the platform port uses IO storage framework. This function is
	responsible for getting the pointer to the initialised non-volatile memory
	entity.

	Function : tftf_plat_get_pwr_domain_tree_desc() [mandatory]
	```````````````````````````````````````````````````````````

	::

	Argument : void
	Return : const unsigned char *

	This function returns the platform topology description array in a suitable
	format as expected by TFTF. The size of the array is expected to be
	``PLATFORM_NUM_AFFS - PLATFORM_CORE_COUNT + 1``. The format used to describe
	this array is :

	1. The first entry in the array specifies the number of power domains at the
	highest power level implemented in the platform. This caters for platforms
	where the power domain tree does not have a single root node e.g. the FVP
	which has two cluster power domains at the highest level (that is, 1).

	2. Each subsequent entry corresponds to a power domain and contains the number
	of power domains that are its direct children.

	The array format is the same as the one used by Trusted Firmware-A and more
	details of its description can be found in the Trusted Firmware-A documentation:
	`docs/psci-pd-tree.rst`_.

	Function : tftf_plat_get_mpidr() [mandatory]
	````````````````````````````````````````````

	::

	Argument : unsigned int
	Return : uint64_t

	This function converts a given `core_pos` into a valid MPIDR if the CPU is
	present in the platform. The `core_pos` is a unique number less than the
	``PLATFORM_CORE_COUNT`` returned by ``platform_get_core_pos()`` for a given
	CPU. This API is used by the topology framework in TFTF to query the presence of
	a CPU and, if present, returns the corresponding MPIDR for it. If the CPU
	referred to by the `core_pos` is absent, then this function returns
	``INVALID_MPID``.

	Function : plat_get_state_prop() [mandatory]
	````````````````````````````````````````````

	::

	Argument : unsigned int
	Return : const plat_state_prop_t *

	This functions returns the ``plat_state_prop_t`` array for all the valid low
	power states from platform for a specified affinity level and returns ``NULL``
	for an invalid affinity level. The array is expected to be NULL-terminated.
	This function is expected to be used by tests that need to compose the power
	state parameter for use in ``PSCI_CPU_SUSPEND`` API or ``PSCI_STAT/RESIDENCY``
	API.

	Function : plat_fwu_io_setup() [mandatory]
	``````````````````````````````````````````

	::

	Argument : void
	Return : void

	This function initializes the IO system used by the firmware update.

	Function : plat_arm_gic_init() [mandatory]
	``````````````````````````````````````````

	::

	Argument : void
	Return : void

	This function initializes the ARM Generic Interrupt Controller (GIC).

	Function : platform_get_core_pos() [mandatory]
	``````````````````````````````````````````````

	::

	Argument : u_register_t
	Return : unsigned int

	This function returns a linear core ID from a MPID.

	Function : plat_crash_console_init() [mandatory]
	````````````````````````````````````````````````

	::

	Argument : void
	Return : int

	This function initializes a platform-specific console for crash reporting.

	Function : plat_crash_console_putc() [mandatory]
	````````````````````````````````````````````````

	::

	Argument : int
	Return : int

	This function prints a character on the platform-specific crash console.

	Function : plat_crash_console_flush() [mandatory]
	`````````````````````````````````````````````````

	::

	Argument : void
	Return : int

	This function waits until all the characters of the platform-specific crash
	console have been actually printed.

	Optional modifications
	----------------------

	The following are helper functions implemented by the test framework that
	perform common platform-specific tasks. A platform may choose to override these
	definitions.

	Function : platform_get_stack()
	```````````````````````````````

	::

	Argument : unsigned long
	Return : unsigned long

	This function returns the base address of the memory stack that has been
	allocated for the CPU specified by MPIDR. The size of the stack allocated to
	each CPU is specified by the platform defined constant ``PLATFORM_STACK_SIZE``.

	Common implementation of this function is provided in
	``plat/common/aarch64/platform_mp_stack.S``.

	Function : tftf_platform_end()
	``````````````````````````````

	::

	Argument : void
	Return : void

	This function performs any operation required by the platform to properly finish
	the test session.

	The default implementation sends an EOT (End Of Transmission) character on the
	UART. This can be used to automatically shutdown the FVP models. When running on
	real hardware, the UART output may be parsed by an external tool looking for
	this character and rebooting the platform for example.

	Function : tftf_plat_reset()
	````````````````````````````

	::

	Argument : void
	Return : void

	This function resets the platform.

	The default implementation uses the ARM watchdog peripheral (`SP805`_) to
	generate a watchdog timeout interrupt. This interrupt remains deliberately
	unserviced, which eventually asserts the reset signal.

	Storage abstraction layer
	-------------------------

	In order to improve platform independence and portability a storage abstraction
	layer is used to store test results to non-volatile platform storage.

	Each platform should register devices and their drivers via the Storage layer.
	These drivers then need to be initialized in ``tftf_platform_setup()`` function.

	It is mandatory to implement at least one storage driver. For the FVP and Juno
	platforms the NOR Flash driver is provided as the default means to store test
	results to storage. The storage layer is described in the header file
	``include/lib/io_storage.h``. The implementation of the common library is in
	``drivers/io/io_storage.c`` and the driver files are located in ``drivers/io/``.


	Build Flags
	-----------

	- PLAT_TESTS_SKIP_LIST

	This build flag can be defined by the platform to control exclusion of some
	testcases from the default test plan for a platform. If used this needs to
	point to a text file which follows the following criteria:

	- Contain a list of tests to skip for this platform.

	- Specify 1 test per line, using the following format:

	::

	testsuite_name/testcase_name

	where ``testsuite_name`` and ``testcase_name`` are the names that appear in
	the XML tests file.

	- Alternatively, it is possible to disable a test suite entirely, which will
	disable all test cases part of this test suite. To do so, only specify the
	test suite name, omitting the ``/testcase_name`` part.

	--------------

	Copyright (c) 2018-2019, Arm Limited. All rights reserved.

	.. _docs/psci-pd-tree.rst: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/psci-pd-tree.rst
	.. _SP805: https://static.docs.arm.com/ddi0270/b/DDI0270.pdf