[PATCH 7/7] doc: Add documentation to describe capsule config file format

[Sughosh Ganu]

The UEFI capsule can be generated either through command-line
parameters, or, by specifying those in a config file. Add
documentation to describe the format of the config file.

Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
---
 doc/develop/uefi/uefi.rst | 64 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/doc/develop/uefi/uefi.rst b/doc/develop/uefi/uefi.rst
index f96762af39..09b32c9921 100644
--- a/doc/develop/uefi/uefi.rst
+++ b/doc/develop/uefi/uefi.rst
@@ -442,6 +442,70 @@ following command can be issued
       --guid c1b629f1-ce0e-4894-82bf-f0a38387e630 \
       optee.bin optee.capsule
 
+Or alternatively, the capsule can be generated through a make target
+
+.. code-block:: bash
+
+    $ make capsule
+
+Issuing the above make command requires specifying the capsule
+parameters through a config file instead. The Kconfig symbol
+CONFIG_EFI_CAPSULE_CFG_FILE is to be used for specifying the path to
+the config file.
+
+The config file describes the parameters that are used for generating
+one or more capsules. The parameters for a given capsule file are
+specified within curly braces, in the form of "key:value" pairs. All
+the parameters that are currently supported by the mkeficapsule tool
+can be specified through the config file.
+
+The following are some example payload parameters specified through
+the config file.
+
+.. code-block:: none
+
+	{
+	    image-guid: 02f4d760-cfd5-43bd-8e2d-a42acb33c660
+	    hardware-instance: 0
+	    monotonic-count: 1
+	    payload: u-boot.bin
+	    image-index: 1
+	    private-key: /path/to/priv/key
+	    pub-key-cert: /path/to/pub/key
+	    capsule: u-boot.capsule
+	}
+	{
+	    image-guid: 4ce292da-1dd8-428d-a1c2-77743ef8b96e
+	    hardware-instance: 0
+	    payload: u-boot.itb
+	    image-index: 2
+	    oemflags: 0x8000
+	    capsule: fit.capsule
+	}
+	{
+	    capsule-type: accept
+	    image-guid: 4ce292da-1dd8-428d-a1c2-77743ef8b96e
+	    capsule: accept.capsule
+	}
+	{
+	    capsule-type: revert
+	    capsule: revert.capsule
+	}
+
+The following are the keys that specify the capsule parameters
+
+..code-block:: none
+
+    image-guid: Image GUID
+    image-index: Image index value
+    private-key: Path to the private key file used for capsule signing
+    pub-key-cert: Path to the public key crt file used for capsule signing
+    payload: Path to the capsule payload file
+    capsule: Path to the output capsule file that is generated
+    hardware-instance: Hardware Instance value
+    monotonic-count: Monotonic count value
+    capsule-type: Specifies capsule type. normal(default), accept or revert
+    oemflags: 16bit Oemflags value to be used(populated in capsule header)
 
 Enabling Capsule Authentication
 *******************************
-- 
2.34.1