1. 23 Jan, 2015 1 commit
    • Soby Mathew's avatar
      Save 'power_state' early in PSCI CPU_SUSPEND call · 31244d74
      Soby Mathew authored
      This patch adds support to save the "power state" parameter before the
      affinity level specific handlers are called in a CPU_SUSPEND call.
      This avoids the need to pass the power_state as a parameter to the
      handlers and Secure Payload Dispatcher (SPD) suspend spd_pm_ops.
      The power_state arguments in the spd_pm_ops operations are now reserved
      and must not be used. The SPD can query the relevant power_state fields
      by using the psci_get_suspend_afflvl() & psci_get_suspend_stateid() APIs.
      
      NOTE: THIS PATCH WILL BREAK THE SPD_PM_OPS INTERFACE. HENCE THE SECURE
      PAYLOAD DISPATCHERS WILL NEED TO BE REWORKED TO USE THE NEW INTERFACE.
      
      Change-Id: I1293d7dc8cf29cfa6a086a009eee41bcbf2f238e
      31244d74
  2. 19 Aug, 2014 2 commits
    • Juan Castillo's avatar
      Add support for PSCI SYSTEM_OFF and SYSTEM_RESET APIs · d5f13093
      Juan Castillo authored
      This patch adds support for SYSTEM_OFF and SYSTEM_RESET PSCI
      operations. A platform should export handlers to complete the
      requested operation. The FVP port exports fvp_system_off() and
      fvp_system_reset() as an example.
      
      If the SPD provides a power management hook for system off and
      system reset, then the SPD is notified about the corresponding
      operation so it can do some bookkeeping. The TSPD exports
      tspd_system_off() and tspd_system_reset() for that purpose.
      
      Versatile Express shutdown and reset methods have been removed
      from the FDT as new PSCI sys_poweroff and sys_reset services
      have been added. For those kernels that do not support yet these
      PSCI services (i.e. GICv3 kernel), the original dtsi files have
      been renamed to *-no_psci.dtsi.
      
      Fixes ARM-software/tf-issues#218
      
      Change-Id: Ic8a3bf801db979099ab7029162af041c4e8330c8
      d5f13093
    • Dan Handley's avatar
      Clarify platform porting interface to TSP · 5a06bb7e
      Dan Handley authored
      * Move TSP platform porting functions to new file:
        include/bl32/tsp/platform_tsp.h.
      
      * Create new TSP_IRQ_SEC_PHY_TIMER definition for use by the generic
        TSP interrupt handling code, instead of depending on the FVP
        specific definition IRQ_SEC_PHY_TIMER.
      
      * Rename TSP platform porting functions from bl32_* to tsp_*, and
        definitions from BL32_* to TSP_*.
      
      * Update generic TSP code to use new platform porting function names
        and definitions.
      
      * Update FVP port accordingly and move all TSP source files to:
        plat/fvp/tsp/.
      
      * Update porting guide with above changes.
      
      Note: THIS CHANGE REQUIRES ALL PLATFORM PORTS OF THE TSP TO
            BE UPDATED
      
      Fixes ARM-software/tf-issues#167
      
      Change-Id: Ic0ff8caf72aebb378d378193d2f017599fc6b78f
      5a06bb7e
  3. 01 Aug, 2014 2 commits
    • Vikram Kanigiri's avatar
      Support asynchronous method for BL3-2 initialization · faaa2e76
      Vikram Kanigiri authored
      This patch adds support for BL3-2 initialization by asynchronous
      method where BL3-1 transfers control to BL3-2 using world switch.
      After BL3-2 initialization, it transfers control to BL3-3 via SPD
      service handler. The SPD service handler initializes the CPU context
      to BL3-3 entrypoint depending on the return function indentifier from
      TSP initialization.
      
      Fixes ARM-software/TF-issues#184
      
      Change-Id: I7b135c2ceeb356d3bb5b6a287932e96ac67c7a34
      faaa2e76
    • Vikram Kanigiri's avatar
      Rework the TSPD setup code · 50e27dad
      Vikram Kanigiri authored
      There is no mechanism which allows the TSPD to specify what SPSR to
      use when entering BL3-2 instead of BL3-3. This patch divides the
      responsibility between tspd_setup() and tspd_init() for initializing
      the TSPD and TSP to support the alternate BL3-2 initialization flow
      where BL3-1 handsover control to BL3-2 instead of BL3-3.
      SPSR generated by TSPD for TSP is preserved due the new division of
      labour which fixes #174.
      
      This patch also moves the cpu_context initialization code from
      tspd_setup() to tspd_init() immediately before entering the TSP.
      Instead tspd_setup() updates the BL3-2 entrypoint info structure
      with the state required for initializing the TSP later.
      
      Fixes  ARM-software/TF-issues#174
      
      Change-Id: Ida0a8a48d466c71d5b07b8c7f2af169b73f96940
      50e27dad
  4. 28 Jul, 2014 1 commit
    • Juan Castillo's avatar
      Rework incorrect use of assert() and panic() in codebase · d3280beb
      Juan Castillo authored
      Assert a valid security state using the macro sec_state_is_valid().
      Replace assert() with panic() in those cases that might arise
      because of runtime errors and not programming errors.
      Replace panic() with assert() in those cases that might arise
      because of programming errors.
      
      Fixes ARM-software/tf-issues#96
      
      Change-Id: I51e9ef0439fd5ff5e0edfef49050b69804bf14d5
      d3280beb
  5. 23 Jun, 2014 1 commit
    • Andrew Thoelke's avatar
      Initialise CPU contexts from entry_point_info · 167a9357
      Andrew Thoelke authored
      Consolidate all BL3-1 CPU context initialization for cold boot, PSCI
      and SPDs into two functions:
      *  The first uses entry_point_info to initialize the relevant
         cpu_context for first entry into a lower exception level on a CPU
      *  The second populates the EL1 and EL2 system registers as needed
         from the cpu_context to ensure correct entry into the lower EL
      
      This patch alters the way that BL3-1 determines which exception level
      is used when first entering EL1 or EL2 during cold boot - this is now
      fully determined by the SPSR value in the entry_point_info for BL3-3,
      as set up by the platform code in BL2 (or otherwise provided to BL3-1).
      
      In the situation that EL1 (or svc mode) is selected for a processor
      that supports EL2, the context management code will now configure all
      essential EL2 register state to ensure correct execution of EL1. This
      allows the platform code to run non-secure EL1 payloads directly
      without requiring a small EL2 stub or OS loader.
      
      Change-Id: If9fbb2417e82d2226e47568203d5a369f39d3b0f
      167a9357
  6. 11 Jun, 2014 1 commit
    • Andrew Thoelke's avatar
      Provide cm_get/set_context() for current CPU · 08ab89d3
      Andrew Thoelke authored
      All callers of cm_get_context() pass the calling CPU MPIDR to the
      function. Providing a specialised version for the current
      CPU results in a reduction in code size and better readability.
      
      The current function has been renamed to cm_get_context_by_mpidr()
      and the existing name is now used for the current-CPU version.
      
      The same treatment has been done to cm_set_context(), although
      only both forms are used at present in the PSCI and TSPD code.
      
      Change-Id: I91cb0c2f7bfcb950a045dbd9ff7595751c0c0ffb
      08ab89d3
  7. 29 May, 2014 1 commit
  8. 27 May, 2014 2 commits
    • Dan Handley's avatar
      Further renames of platform porting functions · 9865ac15
      Dan Handley authored
      Rename the ic_* platform porting functions to plat_ic_* to be
      consistent with the other functions in platform.h. Also rename
      bl31_get_next_image_info() to bl31_plat_get_next_image_ep_info()
      and remove the duplicate declaration in bl31.h.
      
      Change-Id: I4851842069d3cff14c0a468daacc0a891a7ede84
      9865ac15
    • Soby Mathew's avatar
      Fixup Standard SMC Resume Handling · 10b65ecf
      Soby Mathew authored
      This patch fixes a missed return and code alignment issues
      in TSP_FID_RESUME handling.
      
      Change-Id: Icf8aeb76dfd6898745653ce039e3bac45e0a9b3a
      10b65ecf
  9. 23 May, 2014 4 commits
    • Dan Handley's avatar
      Split platform.h into separate headers · 5f0cdb05
      Dan Handley authored
      Previously, platform.h contained many declarations and definitions
      used for different purposes. This file has been split so that:
      
      * Platform definitions used by common code that must be defined
        by the platform are now in platform_def.h. The exact include
        path is exported through $PLAT_INCLUDES in the platform makefile.
      
      * Platform definitions specific to the FVP platform are now in
        /plat/fvp/fvp_def.h.
      
      * Platform API declarations specific to the FVP platform are now
        in /plat/fvp/fvp_private.h.
      
      * The remaining platform API declarations that must be ported by
        each platform are still in platform.h but this file has been
        moved to /include/plat/common since this can be shared by all
        platforms.
      
      Change-Id: Ieb3bb22fbab3ee8027413c6b39a783534aee474a
      5f0cdb05
    • Dan Handley's avatar
      Remove extern keyword from function declarations · c6bc0710
      Dan Handley authored
      Function declarations implicitly have external linkage so do not
      need the extern keyword.
      
      Change-Id: Ia0549786796d8bf5956487e8996450a0b3d79f32
      c6bc0710
    • Andrew Thoelke's avatar
      Use a vector table for TSP entrypoints · 399fb08f
      Andrew Thoelke authored
      The TSP has a number of entrypoints used by the TSP on different
      occasions. These were provided to the TSPD as a table of function
      pointers, and required the TSPD to read the entry in the table,
      which is in TSP memory, in order to program the exception return
      address.
      
      Ideally, the TSPD has no access to the TSP memory.
      
      This patch changes the table of function pointers into a vector
      table of single instruction entrypoints. This allows the TSPD to
      calculate the entrypoint address instead of read it.
      
      Fixes ARM-software/tf-issues#160
      
      Change-Id: Iec6e055d537ade78a45799fbc6f43765a4725ad3
      399fb08f
    • Soby Mathew's avatar
      Non-Secure Interrupt support during Standard SMC processing in TSP · 239b04fa
      Soby Mathew authored
      Implements support for Non Secure Interrupts preempting the
      Standard SMC call in EL1. Whenever an IRQ is trapped in the
      Secure world we securely handover to the Normal world
      to process the interrupt. The normal world then issues
      "resume" smc call to resume the previous interrupted SMC call.
      Fixes ARM-software/tf-issues#105
      
      Change-Id: I72b760617dee27438754cdfc9fe9bcf4cc024858
      239b04fa
  10. 22 May, 2014 7 commits
    • Achin Gupta's avatar
      Add S-EL1 interrupt handling support in the TSPD · b44a4435
      Achin Gupta authored
      This patch adds support in the TSPD for registering a handler for
      S-EL1 interrupts. This handler ferries the interrupts generated in the
      non-secure state to the TSP at 'tsp_fiq_entry'. Support has been added
      to the smc handler to resume execution in the non-secure state once
      interrupt handling has been completed by the TSP.
      
      There is also support for resuming execution in the normal world if
      the TSP receives a EL3 interrupt. This code is currently unused.
      
      Change-Id: I816732595a2635e299572965179f11aa0bf93b69
      b44a4435
    • Achin Gupta's avatar
      Use secure timer to generate S-EL1 interrupts · fa9c08b7
      Achin Gupta authored
      This patch adds support in the TSP to program the secure physical
      generic timer to generate a EL-1 interrupt every half second. It also
      adds support for maintaining the timer state across power management
      operations. The TSPD ensures that S-EL1 can access the timer by
      programming the SCR_EL3.ST bit.
      
      This patch does not actually enable the timer. This will be done in a
      subsequent patch once the complete framework for handling S-EL1
      interrupts is in place.
      
      Change-Id: I1b3985cfb50262f60824be3a51c6314ce90571bc
      fa9c08b7
    • Achin Gupta's avatar
      Add context library API to change a bit in SCR_EL3 · c429b5e9
      Achin Gupta authored
      This patch adds an API to write to any bit in the SCR_EL3 member of
      the 'cpu_context' structure of the current CPU for a specified
      security state. This API will be used in subsequent patches which
      introduce interrupt management in EL3 to specify the interrupt routing
      model when execution is not in EL3.
      
      It also renames the cm_set_el3_elr() function to cm_set_elr_el3()
      which is more in line with the system register name being targeted by
      the API.
      
      Change-Id: I310fa7d8f827ad3f350325eca2fb28cb350a85ed
      c429b5e9
    • Achin Gupta's avatar
      Rework 'state' field usage in per-cpu TSP context · 3ee8a164
      Achin Gupta authored
      This patch lays the foundation for using the per-cpu 'state' field in
      the 'tsp_context' structure for other flags apart from the power state
      of the TSP.
      
      It allocates 2 bits for the power state, introduces the necessary
      macros to manipulate the power state in the 'state' field and
      accordingly reworks all use of the TSP_STATE_* states.
      
      It also allocates a flag bit to determine if the TSP is handling a
      standard SMC. If this flag is set then the TSP was interrupted due to
      non-secure or EL3 interupt depending upon the chosen routing
      model. Macros to get, set and clear this flag have been added as
      well. This flag will be used by subsequent patches.
      
      Change-Id: Ic6ee80bd5895812c83b35189cf2c3be70a9024a6
      3ee8a164
    • Vikram Kanigiri's avatar
      Rework memory information passing to BL3-x images · 6871c5d3
      Vikram Kanigiri authored
      The issues addressed in this patch are:
      
      1. Remove meminfo_t from the common interfaces in BL3-x,
      expecting that platform code will find a suitable mechanism
      to determine the memory extents in these images and provide
      it to the BL3-x images.
      
      2. Remove meminfo_t and bl31_plat_params_t from all FVP BL3-x
      code as the images use link-time information to determine
      memory extents.
      
      meminfo_t is still used by common interface in BL1/BL2 for
      loading images
      
      Change-Id: I4e825ebf6f515b59d84dc2bdddf6edbf15e2d60f
      6871c5d3
    • Vikram Kanigiri's avatar
      Populate BL31 input parameters as per new spec · 4112bfa0
      Vikram Kanigiri authored
      This patch is based on spec published at
      https://github.com/ARM-software/tf-issues/issues/133
      
      It rearranges the bl31_args struct into
      bl31_params and bl31_plat_params which provide the
      information needed for Trusted firmware and platform
      specific data via x0 and x1
      
      On the FVP platform BL3-1 params and BL3-1 plat params
      and its constituents are stored at the start of TZDRAM.
      
      The information about memory availability and size for
      BL3-1, BL3-2 and BL3-3 is moved into platform specific data.
      
      Change-Id: I8b32057a3d0dd3968ea26c2541a0714177820da9
      4112bfa0
    • Vikram Kanigiri's avatar
      Introduce macros to manipulate the SPSR · 23ff9baa
      Vikram Kanigiri authored
      This patch introduces macros (SPSR_64 and SPSR_32) to
      create a SPSR for both aarch32 and aarch64 execution
      states. These macros allow the user to set fields
      in the SPSR depending upon its format.
      The make_spsr() function which did not allow
      manipulation of all the fields in the aarch32 SPSR
      has been replaced by these new macros.
      
      Change-Id: I9425dda0923e8d5f03d03ddb8fa0e28392c4c61e
      23ff9baa
  11. 16 May, 2014 1 commit
    • Soby Mathew's avatar
      Rework BL3-1 unhandled exception handling and reporting · a43d431b
      Soby Mathew authored
      This patch implements the register reporting when unhandled exceptions are
      taken in BL3-1. Unhandled exceptions will result in a dump of registers
      to the console, before halting execution by that CPU. The Crash Stack,
      previously called the Exception Stack, is used for this activity.
      This stack is used to preserve the CPU context and runtime stack
      contents for debugging and analysis.
      
      This also introduces the per_cpu_ptr_cache, referenced by tpidr_el3,
      to provide easy access to some of BL3-1 per-cpu data structures.
      Initially, this is used to provide a pointer to the Crash stack.
      
      panic() now prints the the error file and line number in Debug mode
      and prints the PC value in release mode.
      
      The Exception Stack is renamed to Crash Stack with this patch.
      The original intention of exception stack is no longer valid
      since we intend to support several valid exceptions like IRQ
      and FIQ in the trusted firmware context. This stack is now
      utilized for dumping and reporting the system state when a
      crash happens and hence the rename.
      
      Fixes ARM-software/tf-issues#79 Improve reporting of unhandled exception
      
      Change-Id: I260791dc05536b78547412d147193cdccae7811a
      a43d431b
  12. 06 May, 2014 6 commits
    • Dan Handley's avatar
      Reduce deep nesting of header files · 97043ac9
      Dan Handley authored
      Reduce the number of header files included from other header
      files as much as possible without splitting the files. Use forward
      declarations where possible. This allows removal of some unnecessary
      "#ifndef __ASSEMBLY__" statements.
      
      Also, review the .c and .S files for which header files really need
      including and reorder the #include statements alphabetically.
      
      Fixes ARM-software/tf-issues#31
      
      Change-Id: Iec92fb976334c77453e010b60bcf56f3be72bd3e
      97043ac9
    • Dan Handley's avatar
      Always use named structs in header files · fb037bfb
      Dan Handley authored
      Add tag names to all unnamed structs in header files. This
      allows forward declaration of structs, which is necessary to
      reduce header file nesting (to be implemented in a subsequent
      commit).
      
      Also change the typedef names across the codebase to use the _t
      suffix to be more conformant with the Linux coding style. The
      coding style actually prefers us not to use typedefs at all but
      this is considered a step too far for Trusted Firmware.
      
      Also change the IO framework structs defintions to use typedef'd
      structs to be consistent with the rest of the codebase.
      
      Change-Id: I722b2c86fc0d92e4da3b15e5cab20373dd26786f
      fb037bfb
    • Dan Handley's avatar
      Separate out CASSERT macro into own header · bdbfc3c2
      Dan Handley authored
      Separate out the CASSERT macro out of bl_common.h into its own
      header to allow more efficient header inclusion.
      
      Change-Id: I291be0b6b8f9879645e839a8f0dd1ec9b3db9639
      bdbfc3c2
    • Dan Handley's avatar
      Remove vpath usage in makefiles · bee82417
      Dan Handley authored
      Remove all usage of the vpath keyword in makefiles as it was prone
      to mistakes. Specify the relative paths to source files instead.
      
      Also reorder source files in makefiles alphabetically.
      
      Fixes ARM-software/tf-issues#121
      
      Change-Id: Id15f60655444bae60e0e2165259efac71a50928b
      bee82417
    • Dan Handley's avatar
      Make use of user/system includes more consistent · 35e98e55
      Dan Handley authored
      Make codebase consistent in its use of #include "" syntax for
      user includes and #include <> syntax for system includes.
      
      Fixes ARM-software/tf-issues#65
      
      Change-Id: If2f7c4885173b1fd05ac2cde5f1c8a07000c7a33
      35e98e55
    • Dan Handley's avatar
      Move include and source files to logical locations · 4ecca339
      Dan Handley authored
      Move almost all system include files to a logical sub-directory
      under ./include. The only remaining system include directories
      not under ./include are specific to the platform. Move the
      corresponding source files to match the include directory
      structure.
      
      Also remove pm.h as it is no longer used.
      
      Change-Id: Ie5ea6368ec5fad459f3e8a802ad129135527f0b3
      4ecca339
  13. 26 Mar, 2014 3 commits
    • Andrew Thoelke's avatar
      Place assembler functions in separate sections · 0a30cf54
      Andrew Thoelke authored
      This extends the --gc-sections behaviour to the many assembler
      support functions in the firmware images by placing each function
      into its own code section. This is achieved by creating a 'func'
      macro used to declare each function label.
      
      Fixes ARM-software/tf-issues#80
      
      Change-Id: I301937b630add292d2dec6d2561a7fcfa6fec690
      0a30cf54
    • Achin Gupta's avatar
      Fix build failure due to a typo in TSPD code · 2eb01d34
      Achin Gupta authored
      This patch fixes a build failure when TSPD support is included. The failure was
      due to a missing semi-colon at the end of a C statement in tspd_common.c
      
      Change-Id: I8fbd0d500bd9145b15f862b8686e570b80fcce8c
      2eb01d34
    • Vikram Kanigiri's avatar
      Fix build by correcting asm helper function usage in TSPD · 31526cb0
      Vikram Kanigiri authored
      This patch fixes a regression failure due to the use of functions by the 
      TSPD code which access system registers with partially qualified names. 
      These functions had been removed in an earlier patch. The relevant code 
      has been updated to access these registers with their fully qualified 
      names.
      
      Fixes ARM-software/tf-issues#119
      
      Change-Id: Ide1bc5036e1b8164a42f7b7fe86186ad860e0ef9
      31526cb0
  14. 20 Mar, 2014 1 commit
    • Jeenu Viswambharan's avatar
      Implement standard calls for TSP · 52538b9b
      Jeenu Viswambharan authored
      This patch adds call count, UID and version information SMC calls for
      the Trusted OS, as specified by the SMC calling convention.
      
      Change-Id: I9a3e84ac1bb046051db975d853dcbe9612aba6a9
      52538b9b
  15. 05 Mar, 2014 1 commit
    • Jon Medhurst's avatar
      Update Makefiles to get proper dependency checking working. · 6d55d109
      Jon Medhurst authored
      
      
      This change requires all platforms to now specify a list of source files
      rather than object files.
      
      New source files should preferably be specified by using the path as
      well and we should add this in the future for all files so we can remove
      use of vpath. This is desirable because vpath hides issues like the fact
      that BL2 currently pulls in a BL1 file bl1/aarch64/early_exceptions.S
      and if in the future we added bl2/aarch64/early_exceptions.S then it's
      likely only one of the two version would be used for both bootloaders.
      
      This change also removes the 'dump' build target and simply gets
      bootloaders to always generate a dump file. At the same time the -x
      option is added so the section headers and symbols table are listed.
      
      Fixes ARM-software/tf-issues#11
      
      Change-Id: Ie38f7be76fed95756c8576cf3f3ea3b7015a18dc
      Signed-off-by: default avatarJon Medhurst <tixy@linaro.org>
      6d55d109
  16. 26 Feb, 2014 1 commit
    • Jeenu Viswambharan's avatar
      Implement late binding for runtime hooks · 7f366605
      Jeenu Viswambharan authored
      At present SPD power management hooks and BL3-2 entry are implemented
      using weak references. This would have the handlers bound and registered
      with the core framework at build time, but leaves them dangling if a
      service fails to initialize at runtime.
      
      This patch replaces implementation by requiring runtime handlers to
      register power management and deferred initialization hooks with the
      core framework at runtime. The runtime services are to register the
      hooks only as the last step, after having all states successfully
      initialized.
      
      Change-Id: Ibe788a2a381ef39aec1d4af5ba02376e67269782
      7f366605
  17. 20 Feb, 2014 3 commits
    • Achin Gupta's avatar
      Rework arithmetic operations in Test Secure Payload · 916a2c1e
      Achin Gupta authored
      
      
      This patch reworks the service provided by the TSP to perform common
      arithmetic operations on a set of arguments provided by the non-secure
      world. For a addition, division, subtraction & multiplication operation
      requested on two arguments in x0 and x1 the steps are:
      
      1. TSPD saves the non-secure context and passes the operation and its
         arguments to the TSP.
      
      2. TSP asks the TSPD to return the same arguments once again. This
         exercises an additional SMC path.
      
      3. TSP now has two copies of both x0 and x1. It performs the operation
         on the corresponding copies i.e. in case of addition it returns x0+x0
         and x1+x1.
      
      4. TSPD receives the result, saves the secure context, restores the
         non-secure context and passes the result back to the non-secure
         client.
      
      Change-Id: I6eebfa2ae0a6f28b1d2e11a31f575c7a4b96724b
      Co-authored-by: default avatarJeenu Viswambharan <jeenu.viswambharan@arm.com>
      916a2c1e
    • Achin Gupta's avatar
      Add power management support in the SPD · 607084ee
      Achin Gupta authored
      This patch implements a set of handlers in the SPD which are called by
      the PSCI runtime service upon receiving a power management
      operation. These handlers in turn pass control to the Secure Payload
      image if required before returning control to PSCI. This ensures that
      the Secure Payload has complete visibility of all power transitions in
      the system and can prepare accordingly.
      
      Change-Id: I2d1dba5629b7cf2d53999d39fe807dfcf3f62fe2
      607084ee
    • Achin Gupta's avatar
      Add Test Secure Payload Dispatcher (TSPD) service · 375f538a
      Achin Gupta authored
      
      
      This patch adds the TSPD service which is responsible for managing
      communication between the non-secure state and the Test Secure Payload
      (TSP) executing in S-EL1.
      
      The TSPD does the following:
      
      1. Determines the location of the TSP (BL3-2) image and passes control
         to it for initialization. This is done by exporting the 'bl32_init()'
         function.
      
      2. Receives a structure containing the various entry points into the TSP
         image as a response to being initialized. The TSPD uses this
         information to determine how the TSP should be entered depending on
         the type of operation.
      
      3. Implements a synchronous mechanism for entering into and returning
         from the TSP image. This mechanism saves the current C runtime
         context on top of the current stack and jumps to the TSP through an
         ERET instruction. The TSP issues an SMC to indicate completion of the
         previous request. The TSPD restores the saved C runtime context and
         resumes TSP execution.
      
      This patch also introduces a Make variable 'SPD' to choose the specific
      SPD to include in the build. By default, no SPDs are included in the
      build.
      
      Change-Id: I124da5695cdc510999b859a1bf007f4d049e04f3
      Co-authored-by: default avatarJeenu Viswambharan <jeenu.viswambharan@arm.com>
      375f538a