[PATCH v3 mailbox+firmware 5/6] firmware: turris-mox-rwtm: Add sysfs documentation

["Marek Behún" <marek.behun@nic.cz>]

Add sysfs ABI documentation for the sysfs files created by the
turris-mox-rwtm driver.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
---
 .../testing/sysfs-firmware-turris-mox-rwtm    | 60 +++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-firmware-turris-mox-rwtm

diff --git a/Documentation/ABI/testing/sysfs-firmware-turris-mox-rwtm b/Documentation/ABI/testing/sysfs-firmware-turris-mox-rwtm
new file mode 100644
index 000000000000..ff6cd30f0cf2
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-turris-mox-rwtm
@@ -0,0 +1,60 @@
+What:		/sys/firmware/turris-mox-rwtm/board_version
+Date:		March 2019
+KernelVersion:	5.2
+Contact:	Marek Behún <marek.behun@nic.cz>
+Description:	(R) Board version burned into eFuses of this Turris Mox board.
+		Format: %i
+
+What:		/sys/firmware/turris-mox-rwtm/do_sign
+Date:		March 2019
+KernelVersion:	5.2
+Contact:	Marek Behún <marek.behun@nic.cz>
+Description:	(RW) Gate for writing requests for signature with the ECDSA
+		private key burned into eFuses during the manufacturing process,
+		and also for reading the resulting signature.
+
+		When requesting for signature, a SHA-512 hash of the message to
+		be signed should be written in binary form to this file. This
+		means that a write() operation into this file shall write
+		exactly 64 bytes, buffers of other size are ignored.
+
+		When the signature is done or the rWTM firmware responded with
+		an error, this file is notified via poll, and the result can
+		then be read. On error, the read() operation fails with errno
+		corresponding with the error. On success, 136 bytes are copied
+		to the buffer - 68 bytes for the R value and 68 for the S value
+		of the ECDSA signature, in binary form. These are 2 arrays of 17
+		32-bit words, in big-endian form, most significat word first.
+
+		Format: binary
+
+What:		/sys/firmware/turris-mox-rwtm/mac_address*
+Date:		March 2019
+KernelVersion:	5.2
+Contact:	Marek Behún <marek.behun@nic.cz>
+Description:	(R) MAC addresses burned into eFuses of this Turris Mox board.
+		Format: %pM
+
+What:		/sys/firmware/turris-mox-rwtm/pubkey
+Date:		March 2019
+KernelVersion:	5.2
+Contact:	Marek Behún <marek.behun@nic.cz>
+Description:	(R) ECDSA public key (in pubkey hex compressed form) computed
+		as pair to the ECDSA private key burned into eFuses of this
+		Turris Mox Board.
+		Format: string
+
+What:		/sys/firmware/turris-mox-rwtm/ram_size
+Date:		March 2019
+KernelVersion:	5.2
+Contact:	Marek Behún <marek.behun@nic.cz>
+Description:	(R) RAM size in MiB of this Turris Mox board as was detected
+		during manufacturing and burned into eFuses. Can be 512 or 1024.
+		Format: %i
+
+What:		/sys/firmware/turris-mox-rwtm/serial_number
+Date:		March 2019
+KernelVersion:	5.2
+Contact:	Marek Behún <marek.behun@nic.cz>
+Description:	(R) Serial number burned into eFuses of this Turris Mox device.
+		Format: %016X
-- 
2.19.2