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.. SPDX-License-Identifier: GPL-2.0+
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Nios II
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=======
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Nios II is a 32-bit embedded-processor architecture designed
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specifically for the Altera family of FPGAs.
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Please refer to the link for more information on Nios II:
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https://www.altera.com/products/processors/overview.html
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Please refer to the link for Linux port and toolchains:
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http://rocketboards.org/foswiki/view/Documentation/NiosIILinuxUserManual
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The Nios II port of u-boot is controlled by device tree. Please check
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out doc/README.fdt-control.
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To add a new board/configuration (eg, mysystem) to u-boot, you will need
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three files.
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1. The device tree source which describes the hardware, dts file:
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arch/nios2/dts/mysystem.dts
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2. Default configuration of Kconfig, defconfig file:
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configs/mysystem_defconfig
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3. The legacy board header file:
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include/configs/mysystem.h
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The device tree source must be generated from your qsys/sopc design
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using the sopc2dts tool. Then modified to fit your configuration.
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Please find the sopc2dts download and usage at the wiki:
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http://www.alterawiki.com/wiki/Sopc2dts
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.. code-block:: none
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$ java -jar sopc2dts.jar --force-altr -i mysystem.sopcinfo -o mysystem.dts
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You will need to add additional properties to the dts. Please find an
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example at, arch/nios2/dts/10m50_devboard.dts.
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1. Add "stdout-path=..." property with your serial path to the chosen
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node, like this::
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chosen {
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stdout-path = &uart_0;
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};
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2. If you use SPI/EPCS or I2C, you will need to add aliases to number
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the sequence of these devices, like this::
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aliases {
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spi0 = &epcs_controller;
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};
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Next, you will need a default config file. You may start with
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10m50_defconfig, modify the options and save it.
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.. code-block:: none
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$ make 10m50_defconfig
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$ make menuconfig
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$ make savedefconfig
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$ cp defconfig configs/mysystem_defconfig
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You will need to change the names of board header file and device tree,
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and select the drivers with menuconfig.
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.. code-block:: none
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Nios II architecture --->
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(mysystem) Board header file
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Device Tree Control --->
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(mysystem) Default Device Tree for DT control
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There is a selection of "Provider of DTB for DT control" in the Device
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Tree Control menu.
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* Separate DTB for DT control, will cat the dtb to end of u-boot
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binary, output u-boot-dtb.bin. This should be used for production.
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If you use boot copier, like EPCS boot copier, make sure the copier
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copies all the u-boot-dtb.bin, not just u-boot.bin.
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* Embedded DTB for DT control, will include the dtb inside the u-boot
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binary. This is handy for development, eg, using gdb or nios2-download.
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The last thing, legacy board header file describes those config options
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not covered in Kconfig yet. You may copy it from 10m50_devboard.h::
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$ cp include/configs/10m50_devboard.h include/configs/mysystem.h
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Please change the SDRAM base and size to match your board. The base
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should be cached virtual address, for Nios II with MMU it is 0xCxxx_xxxx
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to 0xDxxx_xxxx.
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.. code-block:: c
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#define CONFIG_SYS_SDRAM_BASE 0xc8000000
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#define CONFIG_SYS_SDRAM_SIZE 0x08000000
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You will need to change the environment variables location and setting,
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too. You may change other configs to fit your board.
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After all these changes, you may build and test::
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$ export CROSS_COMPILE=nios2-elf- (or nios2-linux-gnu-)
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$ make mysystem_defconfig
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$ make
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Enjoy!
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