Draft: docs: add energy gateway

Closes eclipse/oniro-core/docs#40

Signed-off-by: Grzegorz Gwóźdź grzegorz.gwozdz@huawei.com

CC: @kristis

energy_gateway.rst

+.. SPDX-FileCopyrightText: Huawei Inc.
+..
+.. SPDX-License-Identifier: CC-BY-4.0
+
+.. include:: definitions.rst
+
+Residential Energy Gateway Blueprint
+####################################
+
+.. contents::
+   :depth: 4
+
+Overview
+********
+
+The technology industry has blossomed over the past years, and with broad consumer
+support for projects that address the challenges of an aging power delivery 
+infrastructure, the stage is set for the rapid evolution of the energy 
+distribution and consumption.
+The energy distribution market is currently undergoing a serious 
+transformation where all its stakeholders are striving for a change and as
+a result we see inclusion of smart technology in energy eco system. 
+This change is so rapid that in order to keep the pace with growing global
+energy market, the utility provider and home owners are in need of a way
+to enhance the interaction between the grid and the household. 
+At core of all this energy industry there is a need for a smart solution 
+for energy consumers. The smart solution that replaces the current energy 
+network with a democratic business model where energy consumers manage
+their own energy portfolio. 
+
+
+|main_project_name| provides a solution with a residential energy gateway that
+improves transparency, agility, sustainability, and digital innovation.
+This Blueprint builds a residential energy gateway, to gather local energy data,
+provide insight of energy usage in the home. The data will be displayed on a 
+local web dashboard and leveraged locally, as well as, online resources for 
+energy management. 
+
+Use Cases
+*********
+
+The Residential energy Gateway Blueprint, is expected to be ready with the 
+Goofy GA, and will cover the following use cases:
+
+- Data collection of local energy consumers and producers
+  (PV, electric vehicles, heat pumps, HVAC, appliances, smart plugs, etc.).
+  To collect this data Oniro will be extended to support the Modbus RTU and 
+  TCP protocols as well as the upcoming Matter standard.
+- Energy Management rule-set based on collect local data, PV energy forecast
+  and grid energy pricing.
+
+Building and flashing
+*********************
+Building this blueprint for the Rapsberry Pi 4 is similar to 
+`building and flashing a base Linux image <https://docs.oniroproject.org/en/latest/oniro/hardware-support/boards/raspberrypi4.html>`_,
+with the addition of two extra layers.
+
+Linux image
+-----------
+
+1. Follow the `blueprint instructions <https://docs.oniroproject.org/projects/blueprints/en/latest/workspace.html#workspace>`_
+   to set up the workspace.
+
+2. Clone the following layer to your repo's root directory:
+   `energy gateway repository <https://gitlab.eclipse.org/eclipse/oniro-blueprints/energy-gateway/meta-oniro-blueprints-energy-gateway>`_ by running the following commands:
+
+.. code-block:: console
+
+   $ cd $CHECKOUT_DIR
+   $ git clone --recursive https://gitlab.eclipse.org/eclipse/oniro-blueprints/energy-gateway/meta-oniro-blueprints-energy-gateway
+
+.. note::
+   
+   Make sure you define or replace $CHECKOUT_DIR
+
+3. Source the environment with proper template settings, the flavour being
+   *linux* and target machine being *raspberrypi4-64*. Pay attention to how
+   relative paths are constructed. The value of *TEMPLATECONF* is relative to
+   the location of the build directory *./build-linux-raspberrypi4-64*, which
+   is going to be created after this step:
+
+.. code-block:: console
+
+   $ TEMPLATECONF=../oniro/flavours/linux . \
+     ./oe-core/oe-init-build-env build-oniro-linux-raspberrypi4-64
+
+4. You will find yourself in the newly created build directory. Change the 
+   ``conf/bblayers.conf`` file by adding the paths of layers added in the 2nd
+   step to the BBLAYERS variable **or** run the following two commands:
+
+.. code-block:: console
+
+   $ bitbake-layers add-layer $CHECKOUT_DIR/meta-oniro-blueprints-core
+   $ bitbake-layers add-layer $CHECKOUT_DIR/meta-oniro-blueprints-energy-gateway/meta-oniro-blueprints-energy-gateway
+
+5. Call *bitbake* to build the image by running
+   the following command:
+
+.. code-block:: console
+
+   $ MACHINE=raspberrypi4-64 DISTRO="oniro-linux-blueprint-energy-gateway" bitbake blueprint-energy-gateway-image
+
+.. note::
+   
+   You can set the MACHINE and DISTRO variables in the conf/local.conf
+   file.
+
+6. After the build completes, the bootloader, kernel, and rootfs image files
+   can be found in
+   ``build-oniro-linux-raspberrypi4-64/tmp/deploy/images/$MACHINE/``.
+   In order to flash the image, make sure you have plugged in SD
+   card. Once that is done, note its associated device node. You can find that 
+   using `udev`, `dmesg` or various other tools. Once the device not 
+   associated to the microSD card is known, proceed to flash the built image.
+   The key file which is needed to flash into the SD card is
+   ``oniro-image-base-raspberrypi4-64.wic.gz``. To flash it to the SD card
+   use `bmap-tools <https://github.com/intel/bmap-tools>`_ by running the
+   following commands:
+
+.. code-block:: console
+
+   $ cd tmp/deploy/images/raspberrypi4-64
+   $ bmaptool copy oniro-image-base-raspberrypi4-64.wic.gz $DEVNODE
+
+.. note::
+   
+   Change/replace $DEVNODE variable with the device (probably an SD
+   card) you want to flash it to.
+
+.. note::
+   
+   When connecting your SD card to the computer it might get mounted,
+   unmount it before flashing.
+
+Running the blueprint
+*********************
+
+Now you can boot up your Raspberry Pi 4 and log in with default credentials:
+
+* User: ``oniro``
+* Password: ``oniro``
+