1. 06 Oct, 2017 1 commit
  2. 05 Oct, 2017 4 commits
    • Soby Mathew's avatar
      GICv3: ITS architectural save and restore helpers · b258278e
      Soby Mathew authored
      
      
      This patch adds functions to save and restore GICv3 ITS registers during
      system suspend. Please note that the power management of GIC ITS is
      implementation defined. These functions only implements the
      architectural part of the ITS power management and they do not restore
      memory structures or register content required to support ITS. Even if
      the ITS implementation stores structures in memory, an implementation
      defined power down sequence is likely to be required to flush some
      internal ITS caches to memory. If such implementation defined sequence
      is not followed, the platform must ensure that the ITS is not power
      gated during system suspend.
      
      Change-Id: I5f31e5541975aa7dcaab69b0b7f67583c0e27678
      Signed-off-by: default avatarSoby Mathew <soby.mathew@arm.com>
      Signed-off-by: default avatarDouglas Raillard <douglas.raillard@arm.com>
      b258278e
    • Soby Mathew's avatar
      GICv3: add functions for save and restore · ebf1ca10
      Soby Mathew authored
      
      
      During system suspend, the GICv3 Distributor and Redistributor context
      can be lost due to power gating of the system power domain. This means
      that the GICv3 context needs to be saved prior to system suspend and
      restored on wakeup. Currently the consensus is that the Firmware should
      be in charge of this. See tf-issues#464 for more details.
      
      This patch introduces helper APIs in the GICv3 driver to save and
      restore the Distributor and Redistributor contexts. The GICv3 ITS
      context is not considered in this patch because the specification says
      that the details of ITS power management is implementation-defined.
      These APIs are expected to be appropriately invoked by the platform
      layer during system suspend.
      
      Fixes ARM-software/tf-issues#464
      
      Change-Id: Iebb9c6770ab8c4d522546f161fa402d2fe02ec00
      Signed-off-by: default avatarSoby Mathew <soby.mathew@arm.com>
      Signed-off-by: default avatarDouglas Raillard <douglas.raillard@arm.com>
      ebf1ca10
    • Douglas Raillard's avatar
      GICv3: turn some macros into inline functions · a64b4e62
      Douglas Raillard authored
      
      
      Tidy up the code a bit by turning some macros into inline functions
      which allows to remove the do/while(0) idiom and backslashes at the end
      of the line.
      
      Change-Id: Ie41a4ea4a4da507f7b925247b53e85019101d717
      Signed-off-by: default avatarDouglas Raillard <douglas.raillard@arm.com>
      a64b4e62
    • Douglas Raillard's avatar
      GICv3: Fix gic600.c indentation · b50bdcea
      Douglas Raillard authored
      
      
      Reindent the file using tabs as the mix of spaces and tabs confuses some
      editors and leads them to use spaces instead of tabs for new code
      although the coding style mandates tabs.
      
      Change-Id: I87fa4a5d368a048340054b9b3622325f3f7befba
      Signed-off-by: default avatarDouglas Raillard <douglas.raillard@arm.com>
      b50bdcea
  3. 21 Sep, 2017 1 commit
    • Antonio Nino Diaz's avatar
      Fix type of `unsigned long` constants · e47ac1fd
      Antonio Nino Diaz authored
      
      
      The type `unsigned long` is 32 bit wide in AArch32, but 64 bit wide in
      AArch64. This is inconsistent and that's why we avoid using it as per
      the Coding Guidelines. This patch changes all `UL` occurrences to `U`
      or `ULL` depending on the context so that the size of the constant is
      clear.
      
      This problem affected the macro `BIT(nr)`. As long as this macro is used
      to fill fields of registers, that's not a problem, since all registers
      are 32 bit wide in AArch32 and 64 bit wide in AArch64. However, if the
      macro is used to fill the fields of a 64-bit integer, it won't be able
      to set the upper 32 bits in AArch32.
      
      By changing the type of this macro to `unsigned long long` the behaviour
      is always the same regardless of the architecture, as this type is
      64-bit wide in both cases.
      
      Some Tegra platform files have been modified by this patch.
      
      Change-Id: I918264c03e7d691a931f0d1018df25a2796cc221
      Signed-off-by: default avatarAntonio Nino Diaz <antonio.ninodiaz@arm.com>
      e47ac1fd
  4. 01 Aug, 2017 2 commits
    • Jeenu Viswambharan's avatar
      Add SMMUv3 driver · 1154586b
      Jeenu Viswambharan authored
      
      
      The driver has only one API: to initialize an SMMUv3 device. This
      operates on a device that implements secure state, by invalidating
      secure caches and TLBs.
      
      Change-Id: Ief32800419ddf0f1fe38c8f0da8f5ba75c72c826
      Signed-off-by: default avatarJeenu Viswambharan <jeenu.viswambharan@arm.com>
      1154586b
    • Jeenu Viswambharan's avatar
      CCI: Adapt for specific product at run time · e33fd445
      Jeenu Viswambharan authored
      
      
      The current build system and driver requires the CCI product to be
      specified at build time. The device constraints can be determined at run
      time from its ID registers, obviating the need for specifying them
      ahead.
      
      This patch adds changes to identify and validate CCI at run time. Some
      global variables are renamed to be in line with the rest of the code
      base.
      
      The build option ARM_CCI_PRODUCT_ID is now removed, and user guide is
      updated.
      
      Change-Id: Ibb765e349d3bc95ff3eb9a64bde1207ab710a93d
      Signed-off-by: default avatarJeenu Viswambharan <jeenu.viswambharan@arm.com>
      e33fd445
  5. 01 Jun, 2017 1 commit
    • Jeenu Viswambharan's avatar
      Introduce ARM GIC-600 driver · e1c59ab3
      Jeenu Viswambharan authored
      
      
      ARM GIC-600 IP complies with ARM GICv3 architecture, but among others,
      implements a power control register in the Redistributor frame. This
      register must be programmed to mark the frame as powered on, before
      accessing other registers in the frame. Rest of initialization sequence
      remains the same.
      
      The driver provides APIs for Redistributor power management, and
      overrides those in the generic GICv3 driver. The driver data is shared
      between generic GICv3 driver and that of GIC-600.
      
      For FVP platform, the GIC-600 driver is chosen when FVP_USE_GIC_DRIVER
      is set to FVP_GIC600. Also update user guide.
      
      Change-Id: I321b2360728d69f6d4b0a747b2cfcc3fe5a20d67
      Signed-off-by: default avatarJeenu Viswambharan <jeenu.viswambharan@arm.com>
      e1c59ab3
  6. 03 May, 2017 1 commit
  7. 20 Apr, 2017 1 commit
  8. 18 Apr, 2017 1 commit
    • Antonio Nino Diaz's avatar
      TZC: rename included C file to a header · 239b085c
      Antonio Nino Diaz authored
      
      
      C files shouldn't be included into others. This file only contains some
      macros and functions that can be made `static inline`, so it is ok to
      convert it into a header file.
      
      This is the only occurrence of a C file being included in another one in
      the codebase instead of using a header, other occurrences are a way of
      achieving backwards-compatibility.
      
      Functions therein have been qualified as `inline`.
      
      Change-Id: I88fe300f6d85a7f0740ef14c9cb8fa54849218e6
      Signed-off-by: default avatarAntonio Nino Diaz <antonio.ninodiaz@arm.com>
      239b085c
  9. 06 Apr, 2017 1 commit
    • Antonio Nino Diaz's avatar
      Replace tf_printf occurrences with ERROR · 38aecbb4
      Antonio Nino Diaz authored
      
      
      The amount of console output is controlled by the LOG_LEVEL build
      option. Using tf_printf without any #ifdef depending on the LOG_LEVEL
      doesn't give the user that flexibility.
      
      This patch replaces all occurrences of tf_printf that prints error, but
      aren't dependent on LOG_LEVEL, with the ERROR macro.
      
      Change-Id: Ib5147f14fc1579398a11f19ddd0e840ff6692831
      Signed-off-by: default avatarAntonio Nino Diaz <antonio.ninodiaz@arm.com>
      38aecbb4
  10. 31 Mar, 2017 1 commit
  11. 02 Mar, 2017 1 commit
  12. 01 Mar, 2017 1 commit
    • Soby Mathew's avatar
      Flush the GIC driver data after init · 311b1773
      Soby Mathew authored
      
      
      The GIC driver data is initialized by the primary CPU with caches
      enabled. When the secondary CPU boots up, it initializes the
      GICC/GICR interface with the caches disabled and there is a chance that
      the driver data is not yet written back to the memory. This patch fixes
      this problem by flushing the driver data after they have been
      initialized.
      
      Change-Id: Ie9477029683846209593ff005d2bac559bb8f5e6
      Signed-off-by: default avatarSoby Mathew <soby.mathew@arm.com>
      311b1773
  13. 23 Jan, 2017 1 commit
    • Masahiro Yamada's avatar
      Use #ifdef for IMAGE_BL* instead of #if · 3d8256b2
      Masahiro Yamada authored
      
      
      One nasty part of ATF is some of boolean macros are always defined
      as 1 or 0, and the rest of them are only defined under certain
      conditions.
      
      For the former group, "#if FOO" or "#if !FOO" must be used because
      "#ifdef FOO" is always true.  (Options passed by $(call add_define,)
      are the cases.)
      
      For the latter, "#ifdef FOO" or "#ifndef FOO" should be used because
      checking the value of an undefined macro is strange.
      
      Here, IMAGE_BL* is handled by make_helpers/build_macro.mk like
      follows:
      
        $(eval IMAGE := IMAGE_BL$(call uppercase,$(3)))
      
        $(OBJ): $(2)
                @echo "  CC      $$<"
                $$(Q)$$(CC) $$(TF_CFLAGS) $$(CFLAGS) -D$(IMAGE) -c $$< -o $$@
      
      This means, IMAGE_BL* is defined when building the corresponding
      image, but *undefined* for the other images.
      
      So, IMAGE_BL* belongs to the latter group where we should use #ifdef
      or #ifndef.
      Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      3d8256b2
  14. 12 Jan, 2017 1 commit
  15. 15 Dec, 2016 1 commit
  16. 01 Dec, 2016 1 commit
    • Yatharth Kochar's avatar
      AArch32: Miscellaneous fixes in the AArch32 code · 69d59e0c
      Yatharth Kochar authored
      
      
      This patch makes following miscellaneous fixes:
      * pl011_console.S: Fixed the bit mask used to check if the
        transmit FIFO is full or empty.
      * smcc_macros.S: Added `_fsxc` suffix while updating the SPSR.
        By default the assembler assumes `_fc` suffix which does not
        update all the fields in SPSR. By adding `_fsxc` suffix all
        the fields gets updated.
      * platform_helpers.S: Removed the weak definition for
        `plat_my_core_pos()` as this is a mandatory function which
        needs to be defined by all platforms.
      
      Change-Id: I8302292533c943686fff8d7c749a07132c052a3b
      Signed-off-by: default avatarYatharth Kochar <yatharth.kochar@arm.com>
      69d59e0c
  17. 12 Sep, 2016 1 commit
    • Yatharth Kochar's avatar
      GICv3: Allow either G1S or G0 interrupts to be configured · 6083c841
      Yatharth Kochar authored
      Currently the GICv3 driver mandates that platform populate
      both G1S and G0 interrupts. However, it is possible that a
      given platform is not interested in both the groups and
      just needs to specify either one of them.
      
      This patch modifies the `gicv3_rdistif_init()` & `gicv3_distif_init()`
      functions to allow either G1S or G0 interrupts to be configured.
      
      Fixes ARM-software/tf-issues#400
      
      Change-Id: I43572b0e08ae30bed5af9334f25d35bf439b0d2b
      6083c841
  18. 11 Aug, 2016 1 commit
    • Sudeep Holla's avatar
      gicv3: disable Group1 NonSecure interrupts during core powerdown · 65d68ca6
      Sudeep Holla authored
      As per the GICv3 specification, to power down a processor using GICv3
      and allow automatic power-on if an interrupt must be sent to a processor,
      software must set Enable to zero for all interrupt groups(by writing to
      GICC_CTLR or ICC_IGRPEN{0,1}_EL1/3 as appropriate.
      
      Also, NonSecure EL1 software may not be aware of the CPU power state
      details and fail to choose right states that require quiescing the CPU
      interface. So it's preferred that the PSCI implementation handles it as
      it is fully aware of the CPU power states.
      
      This patch adds disabling of Group1 NonSecure interrupts during processor
      power down along with Group0 and Group1 Secure interrupts so that all the
      interrupt groups are handled at once as per specification.
      
      Change-Id: Ib564d773c9c4c41f2ca9471451c030e3de75e641
      65d68ca6
  19. 10 Aug, 2016 2 commits
    • Soby Mathew's avatar
      AArch32: Add console driver · 66be868e
      Soby Mathew authored
      This patch adds console drivers including the pl011 driver
      for the AArch32 mode.
      
      Change-Id: Ifd22520d370fca3e73dbbf6f2d97d6aee65b67dd
      66be868e
    • Soby Mathew's avatar
      AArch32: Enable GIC and TZC support · 367d0ffb
      Soby Mathew authored
      This patch modifies GICv3 and TZC drivers to add AArch32 support.
      No modifications are required for the GICv2 driver for AArch32 support.
      The TZC driver assumes that the secure world is running in Little-Endian
      mode to do 64 bit manipulations. Assertions are present to validate the
      assumption.
      
      Note: The legacy GICv3 driver is not supported for AArch32.
      
      Change-Id: Id1bc75a9f5dafb9715c9500ca77b4606eb1e2458
      367d0ffb
  20. 09 Aug, 2016 1 commit
    • Soby Mathew's avatar
      Move console drivers to AArch64 folder · 9c94d3b3
      Soby Mathew authored
      This patch moves the various assembly console drivers
      into `aarch64` architecture specific folder. Stub files,
      which include files from new location, are retained at the
      original location for platform compatibility reasons.
      
      Change-Id: I0069b6c1c0489ca47f5204d4e26e3bc3def533a8
      9c94d3b3
  21. 27 Jul, 2016 1 commit
    • Soby Mathew's avatar
      GICv3: Fix the GICD_IROUTER offset · 61e30277
      Soby Mathew authored
      This patch fixes the offset of GICD_IROUTER register defined in gicv3.h.
      Although the GICv3 documention mentions that the offset for this register
      is 0x6100-0x7FD8, the offset calculation for an interrupt id `n` is :
      
         0x6000 + 8n, where n >= 32
      
      This requires the offset for GICD_IROUTER to be defined as 0x6000.
      
      Fixes ARM-software/tf-issues#410
      
      Change-Id: If9e91e30d946afe7f1f60fea4f065c7567093fa8
      61e30277
  22. 18 Jul, 2016 1 commit
    • Soby Mathew's avatar
      Rework type usage in Trusted Firmware · 4c0d0390
      Soby Mathew authored
      This patch reworks type usage in generic code, drivers and ARM platform files
      to make it more portable. The major changes done with respect to
      type usage are as listed below:
      
      * Use uintptr_t for storing address instead of uint64_t or unsigned long.
      * Review usage of unsigned long as it can no longer be assumed to be 64 bit.
      * Use u_register_t for register values whose width varies depending on
        whether AArch64 or AArch32.
      * Use generic C types where-ever possible.
      
      In addition to the above changes, this patch also modifies format specifiers
      in print invocations so that they are AArch64/AArch32 agnostic. Only files
      related to upcoming feature development have been reworked.
      
      Change-Id: I9f8c78347c5a52ba7027ff389791f1dad63ee5f8
      4c0d0390
  23. 07 Jul, 2016 1 commit
    • Soby Mathew's avatar
      GIC: Ensure SGIs and PPIs are Group0 before setup · 47c6876a
      Soby Mathew authored
      The legacy GIC driver assumes that the SGIs and PPIs are Group0 during
      initialization. This is true if the driver is the first one to initialize
      the GIC hardware after reset. But in some cases, earlier BL stages could
      have already initialized the GIC hardware which means that SGI and PPI
      configuration are not the expected reset values causing assertion failure
      in `gicd_set_ipriorityr()`. This patch explicitly resets the SGI and PPI
      to Group0 prior to their initialization in the driver. The same patch is
      not done in the GICv2-only driver because unlike in the legacy driver,
      `gicd_set_ipriorityr()` of GICv2 driver doesn't enforce this policy and
      the appropriate group is set irrespective of the initial value.
      
      Fixes ARM-software/tf-issues#396
      
      Change-Id: I521d35caa37470ce542c796c2ba99716e4763105
      47c6876a
  24. 25 May, 2016 1 commit
    • Soby Mathew's avatar
      CCN: Add API to query the PART0 ID from CCN · 6331a31a
      Soby Mathew authored
      This patch adds the API `ccn_get_part0_id` to query the PART0 ID from the
      PERIPHERAL_ID 0 register in the CCN driver. This ID allows to distinguish
      the variant of CCN present on the system and possibly enable dynamic
      configuration of the IP based on the variant. Also added an assert in
      `ccn_master_to_rn_id_map()` to ensure that the master map bitfield provided
      by the platform is within the expected interface id.
      
      Change-Id: I92d2db7bd93a9be8a7fbe72a522cbcba0aba2d0e
      6331a31a
  25. 12 Apr, 2016 1 commit
    • Yatharth Kochar's avatar
      Use unsigned long long instead of uintptr_t in TZC400/DMC500 drivers · 9fbdb802
      Yatharth Kochar authored
      Currently the `tzc400_configure_region` and `tzc_dmc500_configure_region`
      functions uses uintptr_t as the data type for `region_top` and `region_base`
      variables, which will be converted to 32/64 bits for AArch32/AArch64
      respectively. But the expectation is to keep these addresses at least 64 bit.
      
      This patch modifies the data types to make it at least 64 bit by using
      unsigned long long instead of uintptr_t for the `region_top` and
      `region_base` variables. It also modifies the associated macros
      `_tzc##fn_name##_write_region_xxx` accordingly.
      
      Change-Id: I4e3c6a8a39ad04205cf0f3bda336c3970b15a28b
      9fbdb802
  26. 31 Mar, 2016 2 commits
    • Vikram Kanigiri's avatar
      Add ARM CoreLink DMC-500 driver to program TrustZone protection · f568604b
      Vikram Kanigiri authored
      The ARM CoreLink DMC-500 Dynamic Memory Controller provides the
      programmable address region control of a TrustZone Address Space
      Controller. The access permissions can be defined for eight
      separate address regions plus a background or default region.
      This patch adds a DMC-500 driver to define address regions and
      program their access permissions as per ARM 100131_0000_02_en
      (r0p0) document.
      
      Change-Id: I9d33120f9480d742bcf7937e4b876f9d40c727e6
      f568604b
    • Vikram Kanigiri's avatar
      Refactor the ARM CoreLink TZC-400 driver · 6b477063
      Vikram Kanigiri authored
      TrustZone protection can be programmed by both memory and TrustZone
      address space controllers like DMC-500 and TZC-400. These peripherals
      share a similar programmer's view.
      
      Furthermore, it is possible to have multiple instances of each type of
      peripheral in a system resulting in multiple programmer's views.
      For example, on the TZC-400 each of the 4 filter units can be enabled
      or disabled for each region. There is a single set of registers to
      program the region attributes. On the DMC-500, each filter unit has its
      own programmer's view resulting in multiple sets of registers to program
      the region attributes. The layout of the registers is almost the same
      across all these variations.
      
      Hence the existing driver in `tzc400\tzc400.c` is refactored into the
      new driver in `tzc\tzc400.c`. The previous driver file is still maintained
      for compatibility and it is now deprecated.
      
      Change-Id: Ieabd0528e244582875bc7e65029a00517671216d
      6b477063
  27. 24 Feb, 2016 1 commit
    • Juan Castillo's avatar
      Fix potential deadlock in PL011 init function · 8dadabd2
      Juan Castillo authored
      The PL011 initialization function disables the UART, flushes the FIFO
      and waits for the current character to be transmitted before applying
      the configuration and enabling the UART. This waiting might result in
      a deadlock if the FIFO is disabled while another CPU is printing a
      message since the flush of FIFO will never finish.
      
      This patch fixes the problem by removing the flush operation and the
      loop for last character completion from the initialization function.
      The UART is disabled, configured and enabled again.
      
      Change-Id: I1ca0b6bd9f352c12856f10f174a9f6eaca3ab4ea
      8dadabd2
  28. 18 Feb, 2016 1 commit
    • Antonio Nino Diaz's avatar
      Add support for %p in tf_printf() · f0dd061a
      Antonio Nino Diaz authored
      This patch adds support for the `%p` format specifier in tf_printf()
      following the example of the printf implementation of the stdlib used
      in the trusted firmware.
      
      Fixes ARM-software/tf-issues#292
      
      Change-Id: I0b3230c783f735d3e039be25a9405f00023420da
      f0dd061a
  29. 12 Feb, 2016 1 commit
  30. 09 Feb, 2016 3 commits
    • Soby Mathew's avatar
      Move private APIs in gic_common.h to a private header · e9ec3cec
      Soby Mathew authored
      This patch moves the private GIC common accessors from `gic_common.h` to
      a new private header file `gic_common_private.h`. This patch also adds
      additional comments to GIC register accessors to highlight the fact
      that some of them access register values that correspond to multiple
      interrupt IDs. The convention used is that the `set`, `get` and `clr`
      accessors access and modify the values corresponding to a single interrupt
      ID whereas the `read` and `write` GIC register accessors access the raw
      GIC registers and it could correspond to multiple interrupt IDs depending
      on the register accessed.
      
      Change-Id: I2643ecb2533f01e3d3219fcedfb5f80c120622f9
      e9ec3cec
    • Soby Mathew's avatar
      Fix GIC_IPRIORITYR setting in new drivers · 38a78614
      Soby Mathew authored
      The code to set the interrupt priority for secure interrupts in the
      new GICv2 and GICv3 drivers is incorrect. The setup code to configure
      interrupt priorities of secure interrupts, one interrupt at a time, used
      gicd_write_ipriorityr()/gicr_write_ipriority() function affecting
      4 interrupts at a time. This bug did not manifest itself because all the
      secure interrupts were configured to the highest secure priority(0) during
      cold boot and the adjacent non secure interrupt priority would be configured
      later by the normal world. This patch introduces new accessors,
      gicd_set_ipriorityr() and gicr_set_ipriorityr(), for configuring priority
      one interrupt at a time and fixes the the setup code to use the new
      accessors.
      
      Fixes ARM-software/tf-issues#344
      
      Change-Id: I470fd74d2b7fce7058b55d83f604be05a27e1341
      38a78614
    • Soby Mathew's avatar
      Fix race in GIC IPRIORITY and ITARGET accessors · a91e12fb
      Soby Mathew authored
      GICD_IPRIORITYR and GICD_ITARGETSR specifically support byte addressing
      so that individual interrupt priorities can be atomically updated by
      issuing a single byte write. The previous implementation of
      gicd_set_ipriority() and gicd_set_itargetsr() used 32-bit register
      accesses, modifying values for 4 interrupts at a time, using a
      read-modify-write approach. This potentially may cause concurrent changes
      by other CPUs to the adjacent interrupts to be corrupted. This patch fixes
      the issue by modifying these accessors to use byte addressing.
      
      Fixes ARM-software/tf-issues#343
      
      Change-Id: Iec28b5f5074045b00dfb8d5f5339b685f9425915
      a91e12fb
  31. 08 Feb, 2016 1 commit
    • Vikram Kanigiri's avatar
      Bug fix: Rectify logic to enter or exit from DVM domain · 3105f7ba
      Vikram Kanigiri authored
      Currently, `ccn_snoop_dvm_domain_common()` is responsible for providing
      a bitmap of HN-F and HN-I nodes in the interconnect. There is a request
      node (RN) corresponding to the master interface (e.g. cluster) that needs
      to be added or removed from the snoop/DVM domain. This request node is
      removed from or added to each HN-F or HN-I node present in the bitmap
      depending upon the type of domain.
      
      The above logic is incorrect when participation of a master interface in
      the DVM domain has to be managed. The request node should be removed
      from or added to the single Miscellaneous Node (MN) in the system
      instead of each HN-I node.
      
      This patch fixes this by removing the intermediate
      `ccn_snoop_dvm_domain_common()` and instead reads the MN registers to
      get the needed node Id bitmap for snoop(HN-F bitmap) and DVM(MN bitmap)
      domains.
      
      Additionally, it renames `MN_DDC_SET_OFF` to `MN_DDC_SET_OFFSET` to
      be inline with other macros.
      
      Change-Id: Id896046dd0ccc5092419e74f8ac85e31b104f7a4
      3105f7ba
  32. 21 Jan, 2016 1 commit
    • Juan Castillo's avatar
      Disable PL011 UART before configuring it · 9400b40e
      Juan Castillo authored
      The PL011 TRM (ARM DDI 0183G) specifies that the UART must be
      disabled before any of the control registers are programmed. The
      PL011 driver included in TF does not disable the UART, so the
      initialization in BL2 and BL31 is violating this requirement
      (and potentially in BL1 if the UART is enabled after reset).
      
      This patch modifies the initialization function in the PL011
      console driver to disable the UART before programming the
      control registers.
      
      Register clobber list and documentation updated.
      
      Fixes ARM-software/tf-issues#300
      
      Change-Id: I839b2d681d48b03f821ac53663a6a78e8b30a1a1
      9400b40e