tpm: add documentation for sysfs interfaces

Reviewed-by: Peter Huewe <peter.huewe@infineon.com>
Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>

Documentation/ABI/stable/sysfs-class-tpm

+What:		/sys/class/misc/tpmX/device/
+Date:		April 2005
+KernelVersion:	2.6.12
+Contact:	tpmdd-devel@lists.sf.net
+Description:	The device/ directory under a specific TPM instance exposes
+		the properties of that TPM chip
+
+
+What:		/sys/class/misc/tpmX/device/active
+Date:		April 2006
+KernelVersion:	2.6.17
+Contact:	tpmdd-devel@lists.sf.net
+Description:	The "active" property prints a '1' if the TPM chip is accepting
+		commands. An inactive TPM chip still contains all the state of
+		an active chip (Storage Root Key, NVRAM, etc), and can be
+		visible to the OS, but will only accept a restricted set of
+		commands. See the TPM Main Specification part 2, Structures,
+		section 17 for more information on which commands are
+		available.
+
+What:		/sys/class/misc/tpmX/device/cancel
+Date:		June 2005
+KernelVersion:	2.6.13
+Contact:	tpmdd-devel@lists.sf.net
+Description:	The "cancel" property allows you to cancel the currently
+		pending TPM command. Writing any value to cancel will call the
+		TPM vendor specific cancel operation.
+
+What:		/sys/class/misc/tpmX/device/caps
+Date:		April 2005
+KernelVersion:	2.6.12
+Contact:	tpmdd-devel@lists.sf.net
+Description:	The "caps" property contains TPM manufacturer and version info.
+
+		Example output:
+
+		Manufacturer: 0x53544d20
+		TCG version: 1.2
+		Firmware version: 8.16
+
+		Manufacturer is a hex dump of the 4 byte manufacturer info
+		space in a TPM. TCG version shows the TCG TPM spec level that
+		the chip supports. Firmware version is that of the chip and
+		is manufacturer specific.
+
+What:		/sys/class/misc/tpmX/device/durations
+Date:		March 2011
+KernelVersion:	3.1
+Contact:	tpmdd-devel@lists.sf.net
+Description:	The "durations" property shows the 3 vendor-specific values
+		used to wait for a short, medium and long TPM command. All
+		TPM commands are categorized as short, medium or long in
+		execution time, so that the driver doesn't have to wait
+		any longer than necessary before starting to poll for a
+		result.
+
+		Example output:
+
+		3015000 4508000 180995000 [original]
+
+		Here the short, medium and long durations are displayed in
+		usecs. "[original]" indicates that the values are displayed
+		unmodified from when they were queried from the chip.
+		Durations can be modified in the case where a buggy chip
+		reports them in msec instead of usec and they need to be
+		scaled to be displayed in usecs. In this case "[adjusted]"
+		will be displayed in place of "[original]".
+
+What:		/sys/class/misc/tpmX/device/enabled
+Date:		April 2006
+KernelVersion:	2.6.17
+Contact:	tpmdd-devel@lists.sf.net
+Description:	The "enabled" property prints a '1' if the TPM chip is enabled,
+		meaning that it should be visible to the OS. This property
+		may be visible but produce a '0' after some operation that
+		disables the TPM.
+
+What:		/sys/class/misc/tpmX/device/owned
+Date:		April 2006
+KernelVersion:	2.6.17
+Contact:	tpmdd-devel@lists.sf.net
+Description:	The "owned" property produces a '1' if the TPM_TakeOwnership
+		ordinal has been executed successfully in the chip. A '0'
+		indicates that ownership hasn't been taken.
+
+What:		/sys/class/misc/tpmX/device/pcrs
+Date:		April 2005
+KernelVersion:	2.6.12
+Contact:	tpmdd-devel@lists.sf.net
+Description:	The "pcrs" property will dump the current value of all Platform
+		Configuration Registers in the TPM. Note that since these
+		values may be constantly changing, the output is only valid
+		for a snapshot in time.
+
+		Example output:
+
+		PCR-00: 3A 3F 78 0F 11 A4 B4 99 69 FC AA 80 CD 6E 39 57 C3 3B 22 75
+		PCR-01: 3A 3F 78 0F 11 A4 B4 99 69 FC AA 80 CD 6E 39 57 C3 3B 22 75
+		PCR-02: 3A 3F 78 0F 11 A4 B4 99 69 FC AA 80 CD 6E 39 57 C3 3B 22 75
+		PCR-03: 3A 3F 78 0F 11 A4 B4 99 69 FC AA 80 CD 6E 39 57 C3 3B 22 75
+		PCR-04: 3A 3F 78 0F 11 A4 B4 99 69 FC AA 80 CD 6E 39 57 C3 3B 22 75
+		...
+
+		The number of PCRs and hex bytes needed to represent a PCR
+		value will vary depending on TPM chip version. For TPM 1.1 and
+		1.2 chips, PCRs represent SHA-1 hashes, which are 20 bytes
+		long. Use the "caps" property to determine TPM version.
+
+What:		/sys/class/misc/tpmX/device/pubek
+Date:		April 2005
+KernelVersion:	2.6.12
+Contact:	tpmdd-devel@lists.sf.net
+Description:	The "pubek" property will return the TPM's public endorsement
+		key if possible. If the TPM has had ownership established and
+		is version 1.2, the pubek will not be available without the
+		owner's authorization. Since the TPM driver doesn't store any
+		secrets, it can't authorize its own request for the pubek,
+		making it unaccessible. The public endorsement key is gener-
+		ated at TPM menufacture time and exists for the life of the
+		chip.
+
+		Example output:
+
+		Algorithm: 00 00 00 01
+		Encscheme: 00 03
+		Sigscheme: 00 01
+		Parameters: 00 00 08 00 00 00 00 02 00 00 00 00
+		Modulus length: 256
+		Modulus:
+		B4 76 41 82 C9 20 2C 10 18 40 BC 8B E5 44 4C 6C
+		3A B2 92 0C A4 9B 2A 83 EB 5C 12 85 04 48 A0 B6
+		1E E4 81 84 CE B2 F2 45 1C F0 85 99 61 02 4D EB
+		86 C4 F7 F3 29 60 52 93 6B B2 E5 AB 8B A9 09 E3
+		D7 0E 7D CA 41 BF 43 07 65 86 3C 8C 13 7A D0 8B
+		82 5E 96 0B F8 1F 5F 34 06 DA A2 52 C1 A9 D5 26
+		0F F4 04 4B D9 3F 2D F2 AC 2F 74 64 1F 8B CD 3E
+		1E 30 38 6C 70 63 69 AB E2 50 DF 49 05 2E E1 8D
+		6F 78 44 DA 57 43 69 EE 76 6C 38 8A E9 8E A3 F0
+		A7 1F 3C A8 D0 12 15 3E CA 0E BD FA 24 CD 33 C6
+		47 AE A4 18 83 8E 22 39 75 93 86 E6 FD 66 48 B6
+		10 AD 94 14 65 F9 6A 17 78 BD 16 53 84 30 BF 70
+		E0 DC 65 FD 3C C6 B0 1E BF B9 C1 B5 6C EF B1 3A
+		F8 28 05 83 62 26 11 DC B4 6B 5A 97 FF 32 26 B6
+		F7 02 71 CF 15 AE 16 DD D1 C1 8E A8 CF 9B 50 7B
+		C3 91 FF 44 1E CF 7C 39 FE 17 77 21 20 BD CE 9B
+
+		Possible values:
+
+		Algorithm:	TPM_ALG_RSA			(1)
+		Encscheme:	TPM_ES_RSAESPKCSv15		(2)
+				TPM_ES_RSAESOAEP_SHA1_MGF1	(3)
+		Sigscheme:	TPM_SS_NONE			(1)
+		Parameters, a byte string of 3 u32 values:
+			Key Length (bits):	00 00 08 00	(2048)
+			Num primes:		00 00 00 02	(2)
+			Exponent Size:		00 00 00 00	(0 means the
+								 default exp)
+		Modulus Length: 256 (bytes)
+		Modulus:	The 256 byte Endorsement Key modulus
+
+What:		/sys/class/misc/tpmX/device/temp_deactivated
+Date:		April 2006
+KernelVersion:	2.6.17
+Contact:	tpmdd-devel@lists.sf.net
+Description:	The "temp_deactivated" property returns a '1' if the chip has
+		been temporarily dectivated, usually until the next power
+		cycle. Whether a warm boot (reboot) will clear a TPM chip
+		from a temp_deactivated state is platform specific.
+
+What:		/sys/class/misc/tpmX/device/timeouts
+Date:		March 2011
+KernelVersion:	3.1
+Contact:	tpmdd-devel@lists.sf.net
+Description:	The "timeouts" property shows the 4 vendor-specific values
+		for the TPM's interface spec timeouts. The use of these
+		timeouts is defined by the TPM interface spec that the chip
+		conforms to.
+
+		Example output:
+
+		750000 750000 750000 750000 [original]
+
+		The four timeout values are shown in usecs, with a trailing
+		"[original]" or "[adjusted]" depending on whether the values
+		were scaled by the driver to be reported in usec from msecs.