€•u&Œsphinx.addnodes”Œdocument”“”)”}”(Œ rawsource”Œ”Œchildren”]”(Œ translations”Œ LanguagesNode”“”)”}”(hhh]”(hŒ pending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ refdomain”Œstd”Œreftype”Œdoc”Œ reftarget”Œ(/translations/zh_CN/security/tpm/tpm_tis”Œmodname”NŒ classname”NŒ refexplicit”ˆuŒtagname”hhh ubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ(/translations/zh_TW/security/tpm/tpm_tis”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ(/translations/it_IT/security/tpm/tpm_tis”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ(/translations/ja_JP/security/tpm/tpm_tis”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ(/translations/ko_KR/security/tpm/tpm_tis”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒPortuguese (Brazilian)”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ(/translations/pt_BR/security/tpm/tpm_tis”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒSpanish”…””}”hh–sbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ(/translations/sp_SP/security/tpm/tpm_tis”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h hhŒ _document”hŒsource”NŒline”NubhŒcomment”“”)”}”(hŒ SPDX-License-Identifier: GPL-2.0”h]”hŒ SPDX-License-Identifier: GPL-2.0”…””}”hh·sbah}”(h]”h ]”h"]”h$]”h&]”Œ xml:space”Œpreserve”uh1hµhhh²hh³ŒB/var/lib/git/docbuild/linux/Documentation/security/tpm/tpm_tis.rst”h´KubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒTPM FIFO interface driver”h]”hŒTPM FIFO interface driver”…””}”(hhÏh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÍhhÊh²hh³hÇh´KubhŒ paragraph”“”)”}”(hŒÊTCG PTP Specification defines two interface types: FIFO and CRB. The former is based on sequenced read and write operations, and the latter is based on a buffer containing the full command or response.”h]”hŒÊTCG PTP Specification defines two interface types: FIFO and CRB. The former is based on sequenced read and write operations, and the latter is based on a buffer containing the full command or response.”…””}”(hhßh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÝh³hÇh´KhhÊh²hubhÞ)”}”(hXFIFO (First-In-First-Out) interface is used by the tpm_tis_core dependent drivers. Originally Linux had only a driver called tpm_tis, which covered memory mapped (aka MMIO) interface but it was later on extended to cover other physical interfaces supported by the TCG standard.”h]”hXFIFO (First-In-First-Out) interface is used by the tpm_tis_core dependent drivers. Originally Linux had only a driver called tpm_tis, which covered memory mapped (aka MMIO) interface but it was later on extended to cover other physical interfaces supported by the TCG standard.”…””}”(hhíh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÝh³hÇh´K hhÊh²hubhÞ)”}”(hXFor historical reasons above the original MMIO driver is called tpm_tis and the framework for FIFO drivers is named as tpm_tis_core. The postfix "tis" in tpm_tis comes from the TPM Interface Specification, which is the hardware interface specification for TPM 1.x chips.”h]”hXFor historical reasons above the original MMIO driver is called tpm_tis and the framework for FIFO drivers is named as tpm_tis_core. The postfix “tis†in tpm_tis comes from the TPM Interface Specification, which is the hardware interface specification for TPM 1.x chips.”…””}”(hhûh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÝh³hÇh´KhhÊh²hubhÞ)”}”(hXjCommunication is based on a 20 KiB buffer shared by the TPM chip through a hardware bus or memory map, depending on the physical wiring. The buffer is further split into five equal-size 4 KiB buffers, which provide equivalent sets of registers for communication between the CPU and TPM. These communication endpoints are called localities in the TCG terminology.”h]”hXjCommunication is based on a 20 KiB buffer shared by the TPM chip through a hardware bus or memory map, depending on the physical wiring. The buffer is further split into five equal-size 4 KiB buffers, which provide equivalent sets of registers for communication between the CPU and TPM. These communication endpoints are called localities in the TCG terminology.”…””}”(hj h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÝh³hÇh´KhhÊh²hubhÞ)”}”(hXbWhen the kernel wants to send commands to the TPM chip, it first reserves locality 0 by setting the requestUse bit in the TPM_ACCESS register. The bit is cleared by the chip when the access is granted. Once it completes its communication, the kernel writes the TPM_ACCESS.activeLocality bit. This informs the chip that the locality has been relinquished.”h]”hXbWhen the kernel wants to send commands to the TPM chip, it first reserves locality 0 by setting the requestUse bit in the TPM_ACCESS register. The bit is cleared by the chip when the access is granted. Once it completes its communication, the kernel writes the TPM_ACCESS.activeLocality bit. This informs the chip that the locality has been relinquished.”…””}”(hjh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÝh³hÇh´KhhÊh²hubhÞ)”}”(hŒVPending localities are served in order by the chip in descending order, one at a time:”h]”hŒVPending localities are served in order by the chip in descending order, one at a time:”…””}”(hj%h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÝh³hÇh´K!hhÊh²hubhŒ bullet_list”“”)”}”(hhh]”(hŒ list_item”“”)”}”(hŒ#Locality 0 has the lowest priority.”h]”hÞ)”}”(hj<h]”hŒ#Locality 0 has the lowest priority.”…””}”(hj>h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÝh³hÇh´K$hj:ubah}”(h]”h ]”h"]”h$]”h&]”uh1j8hj5h²hh³hÇh´Nubj9)”}”(hŒ%Locality 5 has the highest priority. ”h]”hÞ)”}”(hŒ$Locality 5 has the highest priority.”h]”hŒ$Locality 5 has the highest priority.”…””}”(hjUh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÝh³hÇh´K%hjQubah}”(h]”h ]”h"]”h$]”h&]”uh1j8hj5h²hh³hÇh´Nubeh}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ-”uh1j3h³hÇh´K$hhÊh²hubhÞ)”}”(hŒ•Further information on the purpose and meaning of the localities can be found in section 3.2 of the TCG PC Client Platform TPM Profile Specification.”h]”hŒ•Further information on the purpose and meaning of the localities can be found in section 3.2 of the TCG PC Client Platform TPM Profile Specification.”…””}”(hjqh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÝh³hÇh´K'hhÊh²hubhÉ)”}”(hhh]”(hÎ)”}”(hŒ References”h]”hŒ References”…””}”(hj‚h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÍhjh²hh³hÇh´K+ubhÞ)”}”(hŒ“TCG PC Client Platform TPM Profile (PTP) Specification https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/”h]”(hŒ7TCG PC Client Platform TPM Profile (PTP) Specification ”…””}”(hjh²hh³Nh´NubhŒ reference”“”)”}”(hŒ\https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/”h]”hŒ\https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/”…””}”(hjšh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”jœuh1j˜hjubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÝh³hÇh´K-hjh²hubeh}”(h]”Œ references”ah ]”h"]”Œ references”ah$]”h&]”uh1hÈhhÊh²hh³hÇh´K+ubeh}”(h]”Œtpm-fifo-interface-driver”ah ]”h"]”Œtpm fifo interface driver”ah$]”h&]”uh1hÈhhh²hh³hÇh´Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”hÇuh1hŒcurrent_source”NŒ current_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(hÍNŒ generator”NŒ datestamp”NŒ source_link”NŒ source_url”NŒ toc_backlinks”Œentry”Œfootnote_backlinks”KŒ sectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒ strip_classes”NŒ report_level”KŒ halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ traceback”ˆŒinput_encoding”Œ utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”jâŒerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œ language_code”Œen”Œrecord_dependencies”NŒconfig”NŒ id_prefix”hŒauto_id_prefix”Œid”Œ dump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”hÇŒ _destination”NŒ _config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒ raw_enabled”KŒline_length_limit”M'Œpep_references”NŒ pep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒ rfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œ smart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œ docinfo_xform”KŒsectsubtitle_xform”‰Œ image_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(j¼j¹j´j±uŒ nametypes”}”(j¼‰j´‰uh}”(j¹hÊj±juŒ footnote_refs”}”Œ citation_refs”}”Œ autofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ footnotes”]”Œ citations”]”Œautofootnote_start”KŒsymbol_footnote_start”KŒ id_counter”Œ collections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œ transformer”NŒ include_log”]”Œ decoration”Nh²hub.