1What:		/sys/class/tpm/tpmX/ppi/
2Date:		August 2012
3Kernel Version:	3.6
4Contact:	xiaoyan.zhang@intel.com
5Description:
6		This folder includes the attributes related with PPI (Physical
7		Presence Interface). Only if TPM is supported by BIOS, this
8		folder makes sense. The folder path can be got by command
9		'find /sys/ -name 'pcrs''. For the detail information of PPI,
10		please refer to the PPI specification from
11
12		http://www.trustedcomputinggroup.org/
13
14		In Linux 4.2 ppi was moved to the character device directory.
15		A symlink from tpmX/device/ppi to tpmX/ppi to provide backwards
16		compatibility.
17
18What:		/sys/class/tpm/tpmX/ppi/version
19Date:		August 2012
20Contact:	xiaoyan.zhang@intel.com
21Description:
22		This attribute shows the version of the PPI supported by the
23		platform.
24		This file is readonly.
25
26What:		/sys/class/tpm/tpmX/ppi/request
27Date:		August 2012
28Contact:	xiaoyan.zhang@intel.com
29Description:
30		This attribute shows the request for an operation to be
31		executed in the pre-OS environment. It is the only input from
32		the OS to the pre-OS environment. The request should be an
33		integer value range from 1 to 160, and 0 means no request.
34		This file can be read and written.
35
36What:		/sys/class/tpm/tpmX/ppi/response
37Date:		August 2012
38Contact:	xiaoyan.zhang@intel.com
39Description:
40		This attribute shows the response to the most recent operation
41		request it acted upon. The format is "<request> <response num>
42		: <response description>".
43		This file is readonly.
44
45What:		/sys/class/tpm/tpmX/ppi/transition_action
46Date:		August 2012
47Contact:	xiaoyan.zhang@intel.com
48Description:
49		This attribute shows the platform-specific action that should
50		take place in order to transition to the BIOS for execution of
51		a requested operation. The format is "<action num>: <action
52		description>".
53		This file is readonly.
54
55What:		/sys/class/tpm/tpmX/ppi/tcg_operations
56Date:		August 2012
57Contact:	xiaoyan.zhang@intel.com
58Description:
59		This attribute shows whether it is allowed to request an
60		operation to be executed in the pre-OS environment by the BIOS
61		for the requests defined by TCG, i.e. requests from 1 to 22.
62		The format is "<request> <status num>: <status description>".
63		This attribute is only supported by PPI version 1.2+.
64		This file is readonly.
65
66What:		/sys/class/tpm/tpmX/ppi/vs_operations
67Date:		August 2012
68Contact:	xiaoyan.zhang@intel.com
69Description:
70		This attribute shows whether it is allowed to request an
71		operation to be executed in the pre-OS environment by the BIOS
72		for the verdor specific requests, i.e. requests from 128 to
73		255. The format is same with tcg_operations. This attribute
74		is also only supported by PPI version 1.2+.
75		This file is readonly.
76