[PATCHv5 4/6] doc: describe the scp03 command

[Jorge Ramirez-Ortiz <jorge@foundries.io>]

The Secure Channel Protocol 03 command sends control requests
(enable/provision) to the TEE implementing the protocol between the
processor and the secure element.

Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io>
---
 doc/usage/index.rst |  1 +
 doc/usage/scp03.rst | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 doc/usage/scp03.rst

diff --git a/doc/usage/index.rst b/doc/usage/index.rst
index 5754958d7e..fa1c4160b9 100644
--- a/doc/usage/index.rst
+++ b/doc/usage/index.rst
@@ -29,3 +29,4 @@ Shell commands
    pstore
    sbi
    true
+   scp03
diff --git a/doc/usage/scp03.rst b/doc/usage/scp03.rst
new file mode 100644
index 0000000000..7ff87ed85a
--- /dev/null
+++ b/doc/usage/scp03.rst
@@ -0,0 +1,33 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+scp03 command
+=============
+
+Synopsis
+--------
+
+::
+
+    scp03 enable
+    scp03 provision
+
+Description
+-----------
+
+The *scp03* command calls into a Trusted Application executing in a
+Trusted Execution Environment to enable (if present) the Secure
+Channel Protocol 03 stablished between the processor and the secure
+element.
+
+This protocol encrypts all the communication between the processor and
+the secure element using a set of pre-defined keys. These keys can be
+rotated (provisioned) using the *provision* request.
+
+See also
+--------
+
+For some information on the internals implemented in the TEE, please
+check the GlobalPlatform documentation on `Secure Channel Protocol '03'`_
+
+.. _Secure Channel Protocol '03':
+   https://globalplatform.org/wp-content/uploads/2014/07/GPC_2.3_D_SCP03_v1.1.2_PublicRelease.pdf
-- 
2.30.0