1. 14 Aug, 2014 2 commits
    • Dan Handley's avatar
      Remove redundant io_init() function · 6d16ce0b
      Dan Handley authored
      The intent of io_init() was to allow platform ports to provide
      a data object (io_plat_data_t) to the IO storage framework to
      allocate into. The abstraction was incomplete because io_plat_data_t
      uses a platform defined constant and the IO storage framework
      internally allocates other arrays using platform defined constants.
      
      This change simplifies the implementation by instantiating the
      supporting objects in the IO storage framework itself. There is now
      no need for the platform to call io_init().
      
      The FVP port has been updated accordingly.
      
      THIS CHANGE REQUIRES ALL PLATFORM PORTS THAT USE THE IO STORAGE
      FRAMEWORK TO BE UDPATED.
      
      Change-Id: Ib48ac334de9e538064734334c773f8b43df3a7dc
      6d16ce0b
    • Juan Castillo's avatar
      FVP: make usage of Trusted DRAM optional at build time · 186c1d4b
      Juan Castillo authored
      This patch groups the current contents of the Trusted DRAM region at
      address 0x00_0600_0000 (entrypoint mailboxes and BL3-1 parameters) in
      a single shared memory area that may be allocated to Trusted SRAM
      (default) or Trusted DRAM at build time by setting the
      FVP_SHARED_DATA_LOCATION make variable. The size of this shared
      memory is 4096 bytes.
      
      The combination 'Shared data in Trusted SRAM + TSP in Trusted DRAM'
      is not currently supported due to restrictions in the maximum number
      of mmu tables that can be created.
      
      Documentation has been updated to reflect these changes.
      
      Fixes ARM-software/tf-issues#100
      
      Change-Id: I26ff04d33ce4cacf8d770d1a1e24132b4fc53ff0
      186c1d4b
  2. 13 Aug, 2014 1 commit
    • Dan Handley's avatar
      Fix reset to BL3-1 instructions in user guide · bfb1dd51
      Dan Handley authored
      Fix the instructions for resetting to the BL3-1 entrypoint in the
      user guide. The BL3-1 and BL3-2 image locations changed in the fix
      to ARM-software/tf-issues#117 (commit a1b6db6c).
      
      Fixes ARM-software/tf-issues#237
      
      Change-Id: I764eb17c66034511efb984c0e7cfda29bd99198f
      bfb1dd51
  3. 12 Aug, 2014 2 commits
    • Dan Handley's avatar
      Add concept of console output log levels · 289c28a8
      Dan Handley authored
      Create new LOG_LEVEL build option, which controls the amount of
      console output compiled into the build. This should be one of the
      following:
      
          0  (LOG_LEVEL_NONE)
          10 (LOG_LEVEL_NOTICE)
          20 (LOG_LEVEL_ERROR)
          30 (LOG_LEVEL_WARNING)
          40 (LOG_LEVEL_INFO)
          50 (LOG_LEVEL_VERBOSE)
      
      All log output up to and including the log level is compiled into the
      build. The default value is 40 in debug builds and 20 in release
      builds.
      
      Complement the existing INFO, WARN and ERROR console output macros
      with NOTICE and VERBOSE macros, which are conditionally compiled in
      depending on the value of LOG_LEVEL.
      
      Fixes ARM-software/tf-issues#232
      
      Change-Id: I951e2f333e7b90fc4b1060741d9a6db699d5aa72
      289c28a8
    • Juan Castillo's avatar
      FVP: apply new naming conventions to memory regions · 637ebd2e
      Juan Castillo authored
      Secure ROM at address 0x0000_0000 is defined as FVP_TRUSTED_ROM
      Secure RAM at address 0x0400_0000 is defined as FVP_TRUSTED_SRAM
      Secure RAM at address 0x0600_0000 is defined as FVP_TRUSTED_DRAM
      
      BLn_BASE and BLn_LIMIT definitions have been updated and are based on
      these new memory regions.
      
      The available memory for each bootloader in the linker script is
      defined by BLn_BASE and BLn_LIMIT, instead of the complete memory
      region.
      
      TZROM_BASE/SIZE and TZRAM_BASE/SIZE are no longer required as part of
      the platform porting.
      
      FVP common definitions are defined in fvp_def.h while platform_def.h
      contains exclusively (with a few exceptions) the definitions that are
      mandatory in the porting guide. Therefore, platform_def.h now includes
      fvp_def.h instead of the other way around.
      
      Porting guide has been updated to reflect these changes.
      
      Change-Id: I39a6088eb611fc4a347db0db4b8f1f0417dbab05
      637ebd2e
  4. 11 Aug, 2014 1 commit
    • Soby Mathew's avatar
      Add compilation macro for each BL stage · 27905d0a
      Soby Mathew authored
      This patch defines a compile time macro for each boot loader stage
      which allows compilation of code only for a specific stage.
      
      Change-Id: I3a4068404cd3dc26d652556ca9ca7afea8dd28ef
      27905d0a
  5. 07 Aug, 2014 1 commit
    • Juan Castillo's avatar
      Move up to Linaro 14.07 toolchain · 752b05b0
      Juan Castillo authored
      Tests show a slight reduction in code size compared to 13.11.
      
      User guide updated.
      
      Fixes ARM-software/tf-issues#207
      
      Change-Id: I9b80a5d7820cdfd443cac4d4b63f925b74a8c3a3
      752b05b0
  6. 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
    • Juan Castillo's avatar
      Call platform_is_primary_cpu() only from reset handler · 53fdcebd
      Juan Castillo authored
      The purpose of platform_is_primary_cpu() is to determine after reset
      (BL1 or BL3-1 with reset handler) if the current CPU must follow the
      cold boot path (primary CPU), or wait in a safe state (secondary CPU)
      until the primary CPU has finished the system initialization.
      
      This patch removes redundant calls to platform_is_primary_cpu() in
      subsequent bootloader entrypoints since the reset handler already
      guarantees that code is executed exclusively on the primary CPU.
      
      Additionally, this patch removes the weak definition of
      platform_is_primary_cpu(), so the implementation of this function
      becomes mandatory. Removing the weak symbol avoids other
      bootloaders accidentally picking up an invalid definition in case the
      porting layer makes the real function available only to BL1.
      
      The define PRIMARY_CPU is no longer mandatory in the platform porting
      because platform_is_primary_cpu() hides the implementation details
      (for instance, there may be platforms that report the primary CPU in
      a system register). The primary CPU definition in FVP has been moved
      to fvp_def.h.
      
      The porting guide has been updated accordingly.
      
      Fixes ARM-software/tf-issues#219
      
      Change-Id: If675a1de8e8d25122b7fef147cb238d939f90b5e
      53fdcebd
  7. 28 Jul, 2014 4 commits
    • Soby Mathew's avatar
      Add CPUECTLR_EL1 and Snoop Control register to crash reporting · 8c106902
      Soby Mathew authored
      This patch adds the CPUECTLR_EL1 register and the CCI Snoop Control
      register to the list of registers being reported when an unhandled
      exception occurs.
      
      Change-Id: I2d997f2d6ef3d7fa1fad5efe3364dc9058f9f22c
      8c106902
    • Soby Mathew's avatar
      Implement an assert() callable from assembly code · bc920128
      Soby Mathew authored
      The patch implements a macro ASM_ASSERT() which can
      be invoked from assembly code. When assertion happens,
      file name and line number of the check is written
      to the crash console.
      
      Fixes ARM-software/tf-issues#95
      
      Change-Id: I6f905a068e1c0fa4f746d723f18df60daaa00a86
      bc920128
    • Soby Mathew's avatar
      Introduce crash console APIs for crash reporting · c67b09bd
      Soby Mathew authored
      This patch introduces platform APIs to initialise and
      print a character on a designated crash console.
      For the FVP platform, PL011_UART0 is the designated
      crash console. The platform porting guide is also updated
      to document the new APIs.
      
      Change-Id: I5e97d8762082e0c88c8c9bbb479353eac8f11a66
      c67b09bd
    • Achin Gupta's avatar
      Remove the concept of coherent stacks · 539a7b38
      Achin Gupta authored
      This patch removes the allocation of memory for coherent stacks, associated
      accessor function and some dead code which called the accessor function. It also
      updates the porting guide to remove the concept and the motivation behind using
      stacks allocated in coherent memory.
      
      Fixes ARM-software/tf-issues#198
      
      Change-Id: I00ff9a04f693a03df3627ba39727e3497263fc38
      539a7b38
  8. 11 Jul, 2014 1 commit
    • Sandrine Bailleux's avatar
      Update the documentation about the memory layout on FVP · 46d49f63
      Sandrine Bailleux authored
      Update the "Memory layout on FVP platforms" section in the Firmware
      Design document to reflect the overlaying of BL1 and BL2 images
      by BL3-1 and BL3-2.
      
      Also update the Porting Guide document to mention the
      BL31_PROGBITS_LIMIT and BL32_PROGBITS_LIMIT constants.
      
      Change-Id: I0b23dae5b5b4490a01be7ff7aa80567cff34bda8
      46d49f63
  9. 10 Jul, 2014 1 commit
    • Sandrine Bailleux's avatar
      Add support for BL3-0 image · 93d81d64
      Sandrine Bailleux authored
       - Add support for loading a BL3-0 image in BL2. Information about
         memory extents is populated by platform-specific code. Subsequent
         handling of BL3-0 is also platform specific.
         The BL2 main function has been broken down to improve readability.
         The BL3-2 image is now loaded before the BL3-3 image to align with
         the boot flow.
      
       - Build system: Add support for specifying a BL3-0 image that will be
         included into the FIP image.
      
       - IO FIP driver: Add support for identifying a BL3-0 image inside a
         FIP image.
      
       - Update the documentation to reflect the above changes.
      
      Change-Id: I067c184afd52ccaa86569f13664757570c86fc48
      93d81d64
  10. 09 Jul, 2014 1 commit
    • Dan Handley's avatar
      Refactor fvp gic code to be a generic driver · 1e8c5c4f
      Dan Handley authored
      Refactor the FVP gic code in plat/fvp/fvp_gic.c to be a generic ARM
      GIC driver in drivers/arm/gic/arm_gic.c. Provide the platform
      specific inputs in the arm_gic_setup() function so that the driver
      has no explicit dependency on platform code.
      
      Provide weak implementations of the platform interrupt controller
      API in a new file, plat/common/plat_gic.c. These simply call through
      to the ARM GIC driver.
      
      Move the only remaining FVP GIC function, fvp_gic_init() to
      plat/fvp/aarch64/fvp_common.c and remove plat/fvp/fvp_gic.c
      
      Fixes ARM-software/tf-issues#182
      
      Change-Id: Iea82fe095fad62dd33ba9efbddd48c57717edd21
      1e8c5c4f
  11. 01 Jul, 2014 1 commit
    • Sandrine Bailleux's avatar
      Remove concept of top/bottom image loading · 8f55dfb4
      Sandrine Bailleux authored
      This concept is no longer required since we now support loading of
      images at fixed addresses only.
      
      The image loader now automatically detects the position of the image
      inside the current memory layout and updates the layout such that
      memory fragmentation is minimised.
      
      The 'attr' field of the meminfo data structure, which used to hold
      the bottom/top loading information, has been removed. Also the 'next'
      field has been removed as it wasn't used anywhere.
      
      The 'init_bl2_mem_layout()' function has been moved out of common
      code and put in BL1-specific code. It has also been renamed into
      'bl1_init_bl2_mem_layout'.
      
      Fixes ARM-software/tf-issues#109
      
      Change-Id: I3f54642ce7b763d5ee3b047ad0ab59eabbcf916d
      8f55dfb4
  12. 23 Jun, 2014 1 commit
    • Andrew Thoelke's avatar
      Correctly dimension the PSCI aff_map_node array · 6c0b45d1
      Andrew Thoelke authored
      The array of affinity nodes is currently allocated for 32 entries
      with the PSCI_NUM_AFFS value defined in psci.h. This is not enough
      for large systems, and will substantially over allocate the array
      for small systems.
      
      This patch introduces an optional platform definition
      PLATFORM_NUM_AFFS to platform_def.h. If defined this value is
      used for PSCI_NUM_AFFS, otherwise a value of two times the number
      of CPU cores is used.
      
      The FVP port defines PLATFORM_NUM_AFFS to be 10 which saves
      nearly 1.5KB of memory.
      
      Fixes ARM-software/tf-issues#192
      
      Change-Id: I68e30ac950de88cfbd02982ba882a18fb69c1445
      6c0b45d1
  13. 11 Jun, 2014 1 commit
    • Andrew Thoelke's avatar
      Make the BL3-1 crash reporting optional · 9c22b323
      Andrew Thoelke authored
      This patch makes the console crash dump of processor register
      state optional based on the CRASH_REPORTING make variable.
      
      This defaults to only being enabled for DEBUG builds. This can
      be overridden by setting a different value in the platform
      makefile or on the make command line.
      
      Change-Id: Icfa1b2d7ff0145cf0a85e8ad732f9cee7e7e993f
      9c22b323
  14. 03 Jun, 2014 4 commits
  15. 02 Jun, 2014 1 commit
  16. 30 May, 2014 1 commit
    • Dan Handley's avatar
      Fix porting guide references to platform.h · b68954c8
      Dan Handley authored
      Following recent refactoring changes to platform.h, this commit updates
      porting-guide.md to correctly refer to platform.h and platform_def.h where
      appropriate.
      
      Change-Id: Idf1e77503c24358696f8f3c14caa0cc1d579deb4
      b68954c8
  17. 23 May, 2014 1 commit
    • Sandrine Bailleux's avatar
      doc: Update information about the memory layout · 638363eb
      Sandrine Bailleux authored
      Rework the "Memory layout on FVP platforms" section in the Firmware
      Design document. Add information about where the TSP image fits
      in the memory layout when present.
      
      Add documentation for the base addresses of each bootloader image
      in the porting guide.
      
      Change-Id: I4afb2605e008a1cb28c44a697804f2cb6bb4c9aa
      638363eb
  18. 22 May, 2014 6 commits
    • Dan Handley's avatar
      Allow BL3-2 platform definitions to be optional · 1151c821
      Dan Handley authored
      The generic image loading and IO FIP code no longer forces the
      platform to create BL3-2 (Secure-EL1 Payload) specific
      definitions. The BL3-2 loading code in bl2/bl2main.c is wrapped
      by a #ifdef BL32_BASE blocks, allowing the BL3-2 definitions to
      be optional. Similarly for the name_uuid array defintion in
      drivers/io/io_fip.c.
      
      Also update the porting guide to reflect this change.
      
      The BL3-2 platform definitions remain non-configurably present
      in the FVP port.
      
      Fixes ARM-software/tf-issues#68
      
      Change-Id: Iea28b4e94d87a31f5522f271e290919a8a955460
      1151c821
    • Achin Gupta's avatar
      Introduce interrupt handling framework in BL3-1 · dce74b89
      Achin Gupta authored
      This patch adds a common handler for FIQ and IRQ exceptions in the
      BL3-1 runtime exception vector table. This function determines the
      interrupt type and calls its handler. A crash is reported if an
      inconsistency in the interrupt management framework is detected. In
      the event of a spurious interrupt, execution resumes from the
      instruction where the interrupt was generated.
      
      This patch also removes 'cm_macros.S' as its contents have been moved
      to 'runtime_exceptions.S'
      
      Change-Id: I3c85ecf8eaf43a3fac429b119ed0bd706d2e2093
      dce74b89
    • Achin Gupta's avatar
      Introduce interrupt registration framework in BL3-1 · e1333f75
      Achin Gupta authored
      This patch introduces a framework for registering interrupts routed to
      EL3. The interrupt routing model is governed by the SCR_EL3.IRQ and
      FIQ bits and the security state an interrupt is generated in. The
      framework recognizes three type of interrupts depending upon which
      exception level and security state they should be handled in
      i.e. Secure EL1 interrupts, Non-secure interrupts and EL3
      interrupts. It provides an API and macros that allow a runtime service
      to register an handler for a type of interrupt and specify the routing
      model. The framework validates the routing model and uses the context
      management framework to ensure that it is applied to the SCR_EL3 prior
      to entry into the target security state. It saves the handler in
      internal data structures. An API is provided to retrieve the handler
      when an interrupt of a particular type is asserted. Registration is
      expected to be done once by the primary CPU. The same handler and
      routing model is used for all CPUs.
      
      Support for EL3 interrupts will be added to the framework in the
      future. A makefile flag has been added to allow the FVP port choose
      between ARM GIC v2 and v3 support in EL3. The latter version is
      currently unsupported.
      
      A framework for handling interrupts in BL3-1 will be introduced in
      subsequent patches. The default routing model in the absence of any
      handlers expects no interrupts to be routed to EL3.
      
      Change-Id: Idf7c023b34fcd4800a5980f2bef85e4b5c29e649
      e1333f75
    • Sandrine Bailleux's avatar
      Doc: Add the "Building the Test Secure Payload" section · f860e2cf
      Sandrine Bailleux authored
      Add a section in the user guide explaining how to compile the TSP
      image and include it into the FIP. This includes instructions to make
      the TSP run from Trusted DRAM (rather than Trusted SRAM) on FVP.
      
      Change-Id: I04780757a149eeb5482a12a61e821be947b882c0
      f860e2cf
    • Sandrine Bailleux's avatar
      TSP: Let the platform decide which secure memory to use · 2467f70f
      Sandrine Bailleux authored
      The TSP's linker script used to assume that the TSP would
      execute from secure DRAM. Although it is currently the case
      on FVPs, platforms are free to use any secure memory they wish.
      
      This patch introduces the flexibility to load the TSP into any
      secure memory. The platform code gets to specify the extents of
      this memory in the platform header file, as well as the BL3-2 image
      limit address. The latter definition allows to check in a generic way
      that the BL3-2 image fits in its bounds.
      
      Change-Id: I9450f2d8b32d74bd00b6ce57a0a1542716ab449c
      2467f70f
    • Juan Castillo's avatar
      Reserve some DDR DRAM for secure use on FVP platforms · 364daf93
      Juan Castillo authored
      TZC-400 is configured to set the last 16MB of DRAM1 as secure memory and
      the rest of DRAM as non-secure. Non-secure software must not attempt to
      access the 16MB secure area.
      
      Device tree files (sources and binaries) have been updated to match this
      configuration, removing that memory from the Linux physical memory map.
      
      To use UEFI and Linux with this patch, the latest version of UEFI and
      the updated device tree files are required. Check the user guide in the
      documentation for more details.
      
      Replaced magic numbers with #define for memory region definition in the
      platform security initialization function.
      
      Fixes ARM-software/tf-issues#149
      
      Change-Id: Ia5d070244aae6c5288ea0e6c8e89d92859522bfe
      364daf93
  19. 19 May, 2014 1 commit
    • Harry Liebel's avatar
      Improve BL3-0 documentation · 36eb6a75
      Harry Liebel authored
      Provide some information about the expected use of BL3-0.
      
      Fixes ARM-software/tf-issues#144
      
      Change-Id: I5c8d59a675578394be89481ae4ec39ca37522750
      36eb6a75
  20. 16 May, 2014 3 commits
    • Jeenu Viswambharan's avatar
      Add build configuration for timer save/restore · 2da8d8bf
      Jeenu Viswambharan authored
      At present, non-secure timer register contents are saved and restored as
      part of world switch by BL3-1. This effectively means that the
      non-secure timer stops, and non-secure timer interrupts are prevented
      from asserting until BL3-1 switches back, introducing latency for
      non-secure services. Often, secure world might depend on alternate
      sources for secure interrupts (secure timer or platform timer) instead
      of non-secure timers, in which case this save and restore is
      unnecessary.
      
      This patch introduces a boolean build-time configuration NS_TIMER_SWITCH
      to choose whether or not to save and restore non-secure timer registers
      upon world switch. The default choice is made not to save and restore
      them.
      
      Fixes ARM-software/tf-issues#148
      
      Change-Id: I1b9d623606acb9797c3e0b02fb5ec7c0a414f37e
      2da8d8bf
    • Jeenu Viswambharan's avatar
      Document summary of build options in user guide · c3c1e9b0
      Jeenu Viswambharan authored
      Change-Id: I6bd077955bf3780168a874705974bbe72ea0f5f1
      c3c1e9b0
    • 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
  21. 12 May, 2014 1 commit
    • Andrew Thoelke's avatar
      Fixes for TZC configuration on FVP · 84dbf6ff
      Andrew Thoelke authored
      The TZC configuration on FVP was incorrectly allowing both secure
      and non-secure accesses to the DRAM, which can cause aliasing
      problems for software. It was also not enabling virtio access on
      some models.
      
      This patch fixes both of those issues. The patch also enabless
      non-secure access to the DDR RAM for all devices with defined IDs.
      
      The third region of DDR RAM has been removed from the configuration
      as this is not used in any of the FVP models.
      
      Fixes ARM-software/tf-issues#150
      Fixes ARM-software/tf-issues#151
      
      Change-Id: I60ad5daaf55e14f178affb8afd95d17e7537abd7
      84dbf6ff
  22. 24 Apr, 2014 1 commit
  23. 15 Apr, 2014 1 commit
    • Andrew Thoelke's avatar
      Allocate single stacks for BL1 and BL2 · 2bf28e62
      Andrew Thoelke authored
      The BL images share common stack management code which provides
      one coherent and one cacheable stack for every CPU. BL1 and BL2
      just execute on the primary CPU during boot and do not require
      the additional CPU stacks. This patch provides separate stack
      support code for UP and MP images, substantially reducing the
      RAM usage for BL1 and BL2 for the FVP platform.
      
      This patch also provides macros for declaring stacks and
      calculating stack base addresses to improve consistency where
      this has to be done in the firmware.
      
      The stack allocation source files are now included via
      platform.mk rather than the common BLx makefiles. This allows
      each platform to select the appropriate MP/UP stack support
      for each BL image.
      
      Each platform makefile must be updated when including this
      commit.
      
      Fixes ARM-software/tf-issues#76
      
      Change-Id: Ia251f61b8148ffa73eae3f3711f57b1ffebfa632
      2bf28e62
  24. 08 Apr, 2014 1 commit
    • Sandrine Bailleux's avatar
      Define frequency of system counter in platform code · 9e86490f
      Sandrine Bailleux authored
      BL3-1 architecture setup code programs the system counter frequency
      into the CNTFRQ_EL0 register. This frequency is defined by the
      platform, though. This patch introduces a new platform hook that
      the architecture setup code can call to retrieve this information.
      In the ARM FVP port, this returns the first entry of the frequency
      modes table from the memory mapped generic timer.
      
      All system counter setup code has been removed from BL1 as some
      platforms may not have initialized the system counters at this stage.
      The platform specific settings done exclusively in BL1 have been moved
      to BL3-1. In the ARM FVP port, this consists in enabling and
      initializing the System level generic timer. Also, the frequency change
      request in the counter control register has been set to 0 to make it
      explicit it's using the base frequency. The CNTCR_FCREQ() macro has been
      fixed in this context to give an entry number rather than a bitmask.
      
      In future, when support for firmware update is implemented, there
      is a case where BL1 platform specific code will need to program
      the counter frequency. This should be implemented at that time.
      
      This patch also updates the relevant documentation.
      
      It properly fixes ARM-software/tf-issues#24
      
      Change-Id: If95639b279f75d66ac0576c48a6614b5ccb0e84b
      9e86490f