0001 What: /sys/class/tpm/tpmX/ppi/
0002 Date: August 2012
0003 KernelVersion: 3.6
0004 Contact: xiaoyan.zhang@intel.com
0005 Description:
0006 This folder includes the attributes related with PPI (Physical
0007 Presence Interface). Only if TPM is supported by BIOS, this
0008 folder makes sense. The folder path can be got by command
0009 'find /sys/ -name 'pcrs''. For the detail information of PPI,
0010 please refer to the PPI specification from
0011
0012 http://www.trustedcomputinggroup.org/
0013
0014 In Linux 4.2 ppi was moved to the character device directory.
0015 A symlink from tpmX/device/ppi to tpmX/ppi to provide backwards
0016 compatibility.
0017
0018 What: /sys/class/tpm/tpmX/ppi/version
0019 Date: August 2012
0020 Contact: xiaoyan.zhang@intel.com
0021 Description:
0022 This attribute shows the version of the PPI supported by the
0023 platform.
0024 This file is readonly.
0025
0026 What: /sys/class/tpm/tpmX/ppi/request
0027 Date: August 2012
0028 Contact: xiaoyan.zhang@intel.com
0029 Description:
0030 This attribute shows the request for an operation to be
0031 executed in the pre-OS environment. It is the only input from
0032 the OS to the pre-OS environment. The request should be an
0033 integer value range from 1 to 160, and 0 means no request.
0034 This file can be read and written.
0035
0036 What: /sys/class/tpm/tpmX/ppi/response
0037 Date: August 2012
0038 Contact: xiaoyan.zhang@intel.com
0039 Description:
0040 This attribute shows the response to the most recent operation
0041 request it acted upon. The format is "<request> <response num>
0042 : <response description>".
0043 This file is readonly.
0044
0045 What: /sys/class/tpm/tpmX/ppi/transition_action
0046 Date: August 2012
0047 Contact: xiaoyan.zhang@intel.com
0048 Description:
0049 This attribute shows the platform-specific action that should
0050 take place in order to transition to the BIOS for execution of
0051 a requested operation. The format is "<action num>: <action
0052 description>".
0053 This file is readonly.
0054
0055 What: /sys/class/tpm/tpmX/ppi/tcg_operations
0056 Date: August 2012
0057 Contact: xiaoyan.zhang@intel.com
0058 Description:
0059 This attribute shows whether it is allowed to request an
0060 operation to be executed in the pre-OS environment by the BIOS
0061 for the requests defined by TCG, i.e. requests from 1 to 22.
0062 The format is "<request> <status num>: <status description>".
0063 This attribute is only supported by PPI version 1.2+.
0064 This file is readonly.
0065
0066 What: /sys/class/tpm/tpmX/ppi/vs_operations
0067 Date: August 2012
0068 Contact: xiaoyan.zhang@intel.com
0069 Description:
0070 This attribute shows whether it is allowed to request an
0071 operation to be executed in the pre-OS environment by the BIOS
0072 for the verdor specific requests, i.e. requests from 128 to
0073 255. The format is same with tcg_operations. This attribute
0074 is also only supported by PPI version 1.2+.
0075 This file is readonly.
