[PATCH v1 12/12] doc: board: econet: add EN75xx documentation

[AK Sharma <maskachoska@yahoo.com>]

Add the EcoNet vendor index and the EN7528 porting notes.

Signed-off-by: AK Sharma <maskachoska@yahoo.com>
---
 doc/board/econet/en7528.rst | 39 +++++++++++++++++++++++++++++++++++++
 doc/board/econet/index.rst  | 10 ++++++++++
 doc/board/index.rst         |  1 +
 3 files changed, 50 insertions(+)
 create mode 100644 doc/board/econet/en7528.rst
 create mode 100644 doc/board/econet/index.rst

diff --git a/doc/board/econet/en7528.rst b/doc/board/econet/en7528.rst
new file mode 100644
index 00000000..fc4eaf2e
--- /dev/null
+++ b/doc/board/econet/en7528.rst
@@ -0,0 +1,39 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+EN7528 reference board
+======================
+
+This target provides the U-Boot port for the MIPS-based EcoNet/Airoha
+EN7528 SoC (MIPS 1004Kc, little-endian), used in many GPON/XPON ONT home
+gateways. It replaces the proprietary multi-stage TCBoot flow with the
+U-Boot TPL, SPL and U-Boot proper stages.
+
+Boot flow
+---------
+
+The boot ROM starts the TPL from the uncached flash window at
+``0xbfc00000``. The TPL enables the Front-End SRAM, initializes the serial
+port and reads the DDR calibration image and SPL through the early SFC
+reader. After DDR initialization, SPL loads ``u-boot.img`` into DRAM.
+
+Build
+-----
+
+.. code-block:: bash
+
+    make en7528_reference_defconfig
+    make CROSS_COMPILE=mipsel-linux-
+
+Defconfigs
+----------
+
+- ``en7528_reference_defconfig`` - reference board (DASAN H660GM-A)
+- ``en7528_ram_defconfig`` - RAM / chainloaded build
+- ``en7528_jcow414_r3hook_defconfig`` - JioFiber JCOW414 R3-hook variant
+
+DDR calibration blob
+--------------------
+
+The TPL loads a vendor DDR calibration stage from flash; it is not part of
+the U-Boot source. See ``arch/mips/mach-en75xx/README.ddr-blob`` for how to
+extract it from the vendor bootloader and where to flash it.
diff --git a/doc/board/econet/index.rst b/doc/board/econet/index.rst
new file mode 100644
index 00000000..d691db07
--- /dev/null
+++ b/doc/board/econet/index.rst
@@ -0,0 +1,10 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+EcoNet/Airoha
+=============
+
+.. toctree::
+   :maxdepth: 2
+
+   en7512
+   en7528
diff --git a/doc/board/index.rst b/doc/board/index.rst
index fcb4224b..60d75003 100644
--- a/doc/board/index.rst
+++ b/doc/board/index.rst
@@ -29,6 +29,7 @@ Board-specific doc
    coreboot/index
    emcraft/index
    emulation/index
+   econet/index
    gateworks/index
    google/index
    highbank/index
-- 
2.53.0