Add README.nios2 about how to add nios2 boards to u-boot.
Signed-off-by: Thomas Chou thomas@wytron.com.tw --- doc/README.nios2 | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) create mode 100644 doc/README.nios2
diff --git a/doc/README.nios2 b/doc/README.nios2 new file mode 100644 index 0000000..9f248ac --- /dev/null +++ b/doc/README.nios2 @@ -0,0 +1,86 @@ +Nios II is a 32-bit embedded-processor architecture designed +specifically for the Altera family of FPGAs. + +Please refer to the link for more information on Nios II, +https://www.altera.com/products/processors/overview.html + +Please refer to the link for Linux port and toolchains, +http://rocketboards.org/foswiki/view/Documentation/NiosIILinuxUserManual + +The Nios II port of u-boot is controlled by device tree. To add a new +board/configuration (eg, mysystem) to u-boot, you will need three files. + +1. The device tree source which descibe the hardware, dts file. + arch/nios2/dts/mysystem.dts + +2. Default configuration of Kconfig, defconfig file. + configs/mysystem_defconfig + +3. The legacy board header file. + include/configs/mysystem.h + +The device tree source must be generated from your qsys/sopc design file +using the sopc2dts tool. Then modified to fit your configuration. Please +find the sopc2dts download and usage at the wiki, +http://www.alterawiki.com/wiki/Sopc2dts + +java -jar sopc2dts.jar --force-altr -i mysystem.sopcinfo -o mysystem.dts + +You will need to add additional properties to the dts. Please find an +example at, arch/nios2/dts/3c120_devboard.dts. + +1. Add "u-boot,dm-pre-reloc" property to the cpu and the serial node +which you will use for console. + +2. Add "stdout-path=..." property with your serial path to the chosen +node. + +Next, you will need a default config file. You may start with +nios2-generic_defconfig, modify the options and save it. + +make nios2-generic_defconfig +make menuconfig +make savedefconfig +cp defconfig configs/mysystem_defconfig + +You will need to change the names of board header file and device tree, +and select the drivers. + +Nios II architecture ---> + (mysystem) Board header file +Device Tree Control ---> + (mysystem) Default Device Tree for DT control + +There is a selection of "Provider of DTB for DT control" in the Device +Tree Control menu. + +( ) Separate DTB for DT control, will cat the dtb to end of u-boot +binary, output u-boot-dtb.bin. This should be used for production. +If you use boot copier, like epcs boot copier, make sure the copier +copies all the u-boot-dtb.bin, not just u-boot.bin. + +( ) Embedded DTB for DT control, will include the dtb inside the u-boot +binary. This is handy for development, eg, using gdb or nios2-download. + +The last thing, legacy board header file describes those config options +not covered in Kconfig yet. You may copy it from nios2-generic.h. + +cp include/configs/nios2-generic.h include/configs/mysystem.h + +Please change the sdram base and size to your board. The base should be +cached virtual address, for nios2 with mmu it is 0xCxxx-xxxx to +0xDxxx-xxxx. + +#define CONFIG_SYS_SDRAM_BASE 0xD0000000 +#define CONFIG_SYS_SDRAM_SIZE 0x08000000 + +You will need to change the environment variables location and setting, +too. You may change other configs to fit your board. + +After all these changes, you may build and test. + +export CROSS_COMPILE=nios2-elf- (or nios2-linux-gnu-) +make mysystem_defconfig +make + +Enjoy!