board: Add new Broadcom Northstar board
This adds a simple Northstar "BRCMNS" board to be used with
the BCM4708x and BCM5301x chips.
The main intention is to use this with the D-Link DIR-890L
and DIR-885L routers for loading the kernel into RAM from
NAND memory using the BCH-1 ECC and using the separately
submitted SEAMA load command, so we are currently not adding
support for things such as networking.
The DTS file is a multiplatform NorthStar board, designed to
be usable with several NorthStar designs by avoiding any
particulars not related to the operation of U-Boot.
If other board need other ECC for example, they need to
create a separate DTS file and augment the code, but I don't
know if any other users will turn up.
Cc: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/doc/board/broadcom/northstar.rst b/doc/board/broadcom/northstar.rst
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+.. SPDX-License-Identifier: GPL-2.0+
+.. Copyright (C) 2023 Linus Walleij <linus.walleij@linaro.org>
+
+Broadcom Northstar Boards
+=========================
+
+This document describes how to use U-Boot on the Broadcom Northstar
+boards, comprised of the Cortex A9 ARM-based BCM470x and BCM5301x SoCs. These
+were introduced in 2012-2013 and some of them are also called StrataGX.
+
+Northstar is part of the iProc SoC family.
+
+A good overview of these boards can be found in Jon Mason's presentation
+"Enabling New Hardware in U-Boot" where the difference between Northstar
+and Northstar Plus and Northstar 2 (Aarch64) is addressed.
+
+The ROM in the Northstar SoC will typically look into NOR flash memory
+for a boot loader, and the way this works is undocumented. It should be
+possible to execute U-Boot as the first binary from the NOR flash but
+this usage path is unexplored. Please add information if you know more.
+
+D-Link Boards
+-------------
+
+When we use U-Boot with D-Link routers, the NOR flash has a boot loader
+and web server that can re-flash the bigger NAND flash memory for object
+code in the SEAMA format, so on these platforms U-Boot is converted into
+a SEAMA binary and installed in the SoC using the flash tool resident in
+the NOR flash. Details can be found in the OpenWrt project codebase.
+
+Configure
+---------
+
+.. code-block:: console
+
+ $ make CROSS_COMPILE=${CROSS_COMPILE} bcmns_defconfig
+
+Build
+-----
+
+.. code-block:: console
+
+ $ make CROSS_COMPILE=${CROSS_COMPILE}
+ $ ${CROSS_COMPILE}strip u-boot