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spin_table.h

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  • Forked from Reform / reform-boundary-uboot
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    • Masahiro Yamada's avatar
      6b6024ea
      arm64: add better and more generic spin-table support · 6b6024ea
      Masahiro Yamada authored
      
      There are two enable methods supported by ARM64 Linux; psci and
      spin-table.  The latter is simpler and helpful for quick SoC bring
      up.  My main motivation for this patch is to improve the spin-table
      support, which allows us to boot an ARMv8 system without the ARM
      Trusted Firmware.
      
      Currently, we have multi-entry code in arch/arm/cpu/armv8/start.S
      and the spin-table is supported in a really ad-hoc way, and I see
      some problems:
      
        - We must hard-code CPU_RELEASE_ADDR so that it matches the
          "cpu-release-addr" property in the DT that comes from the
          kernel tree.
      
        - The Documentation/arm64/booting.txt in Linux requires that
          the release address must be zero-initialized, but it is not
          cared by the common code in U-Boot.  We must do it in a board
          function.
      
        - There is no systematic way to protect the spin-table code from
          the kernel.  We are supposed to do it in a board specific manner,
          but it is difficult to predict where the spin-table code will be
          located after the relocation.  So, it also makes difficult to
          hard-code /memreserve/ in the DT of the kernel.
      
      So, here is a patch to solve those problems; the DT is run-time
      modified to reserve the spin-table code (+ cpu-release-addr).
      Also, the "cpu-release-addr" property is set to an appropriate
      address after the relocation, which means we no longer need the
      hard-coded CPU_RELEASE_ADDR.
      
      Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      6b6024ea
      History
      arm64: add better and more generic spin-table support
      Masahiro Yamada authored
      
      There are two enable methods supported by ARM64 Linux; psci and
      spin-table.  The latter is simpler and helpful for quick SoC bring
      up.  My main motivation for this patch is to improve the spin-table
      support, which allows us to boot an ARMv8 system without the ARM
      Trusted Firmware.
      
      Currently, we have multi-entry code in arch/arm/cpu/armv8/start.S
      and the spin-table is supported in a really ad-hoc way, and I see
      some problems:
      
        - We must hard-code CPU_RELEASE_ADDR so that it matches the
          "cpu-release-addr" property in the DT that comes from the
          kernel tree.
      
        - The Documentation/arm64/booting.txt in Linux requires that
          the release address must be zero-initialized, but it is not
          cared by the common code in U-Boot.  We must do it in a board
          function.
      
        - There is no systematic way to protect the spin-table code from
          the kernel.  We are supposed to do it in a board specific manner,
          but it is difficult to predict where the spin-table code will be
          located after the relocation.  So, it also makes difficult to
          hard-code /memreserve/ in the DT of the kernel.
      
      So, here is a patch to solve those problems; the DT is run-time
      modified to reserve the spin-table code (+ cpu-release-addr).
      Also, the "cpu-release-addr" property is set to an appropriate
      address after the relocation, which means we no longer need the
      hard-coded CPU_RELEASE_ADDR.
      
      Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>