chapter2: require the TCG2 protocol if system has a TPM

Require the EFI_TCG2_PROTOCOL on systems with a TPM. Introduce a new "UEFI Protocols" section for that. Add a reference to the TCG specification. Fixes: #65 Suggested-by: Heinrich Schuchardt <[email protected]> Signed-off-by: Vincent Stehlé <[email protected]>
ARM-software · Mar 12, 2024 · b3a2882 · b3a2882
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diff --git a/source/chapter2-uefi.rst b/source/chapter2-uefi.rst
@@ -22,6 +22,8 @@ in :UEFI:`2.6`.
 However, the EBBR target market has a reduced set of requirements,
 and so some UEFI features are omitted as unnecessary.
 
+.. _section-required-elems:
+
 Required Elements
 -----------------
 
@@ -67,6 +69,8 @@ All of the following UEFI elements are required for EBBR compliance.
    * - `EFI_DECOMPRESS_PROTOCOL`
      - Native EFI decompression is rarely used and therefore not required.
 
+.. _section-required-plat-specific-elems:
+
 Required Platform Specific Elements
 -----------------------------------
 
@@ -371,6 +375,22 @@ The DTB must be contained in memory of type `EfiACPIReclaimMemory`.
 .. [#ACPIMemNote] `EfiACPIReclaimMemory` was chosen to match the recommendation
    for ACPI tables which fulfill the same task as the DTB.
 
+UEFI Protocols
+==============
+
+Requirements for protocols defined in the UEFI specification are described in
+sections :ref:`section-required-elems` and
+:ref:`section-required-plat-specific-elems`.
+
+The following sections give additional requirements, for protocols not defined
+in the UEFI specification.
+
+Trusted Platform Module (TPM)
+-----------------------------
+
+Not all embedded systems include a TPM but if a TPM is present, then firmware
+shall implement the `EFI_TCG2_PROTOCOL` as defined in [TCG2]_.
+
 UEFI Boot Services
 ==================
 

diff --git a/source/references.rst b/source/references.rst
@@ -55,3 +55,7 @@ Bibliography
    Version 20211203
 
 .. [RVUEFI] `RISC-V UEFI Protocol Specification <https://github.com/riscv-non-isa/riscv-uefi/releases/download/1.0.0/RISCV_UEFI_PROTOCOL-spec.pdf>`_
+
+.. [TCG2] `TCG EFI Protocol Specification, Family “2.0”, Level 00 Revision 00.13.
+   <https://trustedcomputinggroup.org/wp-content/uploads/EFI-Protocol-Specification-rev13-160330final.pdf>`_
+   March 2016, `Trusted Computing Group <http://www.trustedcomputinggroup.org/>`_