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Read First
On this page, please note the following:
- "RZ/G2L" = RZ/G2L, RZ/G2LC, RZ/G2UL. The instructions are the same.
Source Code Repository
The source code for u-boot is stored on github.
Refer to the table in the wiki section of the repository to determine which branch you should use based on your SoC.
After you clone the repository and check out the correct branch, you may want to do is to create a new branch for your edits. This will make it easier to pull in future updates.
Example:
$ git clone https://github.com/renesas-rz/renesas-u-boot-cip $ cd renesas-u-boot-cip $ git checkout v2021.10/rz $ git checkout -b my_board # This will make a new branch named 'my_board'
Add custom board files
SoC: RZ/G2E, RZ/G2N, RZ/G2M, RZ/G2H
Content: TBD
SoC: RZ/G2L, RZ/V2L
1) Device Tree: You are required to add your own custom Device Tree file to the build in directory arch/arm/dts/. That is discussed in more detail later in the Device Tree section below.
2) Board Directory and Files: You need to create the custom board support directory: board/<vendor>/my_custom_board/, that would need to be populated with Kconfig, Makefile and my_custom_board.c. These files will allow you to add custom source code to do things like set register values or make custom functions.
mkdir -p board/<vendor>/my_custom_board cp board/renesas/rzg2l-dev/* board/<vendor>/my_custom_board cp -r board/renesas/rcar-common/ board/<vendor>/ mv board/<vendor>/my_custom_board/rzg2l-dev.c board/<vendor>/my_custom_board/my_custom_board.c
3) Kconfig: Edit the newly created files, board/<vendor>/my_custom_board/Kconfig:
if TARGET_MY_CUSTOM_BOARD
config SYS_SOC
default "rmobile"
config SYS_BOARD
default "my_custom_board"
config SYS_VENDOR
default "<vendor>"
config SYS_CONFIG_NAME
default "my_custom_board"
endif
4) Makefile: Edit board/<vendor>/my_custom_board/Makefile to rename the object file related to the .c file. Then board/<vendor>/my_custom_board.c file could be left unchanged, at least at the first stages. Of course you might want to modify it later on.
# # board/<vendor>/my_custom_board/Makefile # # Copyright (C) 2015 Renesas Electronics Corporation # # SPDX-License-Identifier: GPL-2.0+ # ifdef CONFIG_SPL_BUILD obj-y := ../../renesas/rcar-common/gen3-spl.o else obj-y := my_custom_board.o ../../renesas/rcar-common/common.o endif
5) defconfig: Next step is to create/copy the board configuration:
cp configs/rzg2l-dev_defconfig configs/<vendor>_my_custom_board_defconfig
6) Board header file: Next step is to create/copy a board header file: include/configs/my_board.h. Again, you can take the Renesas files as template. This is the file you want to edit to configure, among other things, different parameters like default extra u-boot environment variables and boot command.
cp include/configs/smarc-rzg2l.h include/configs/my_custom_board.h
7) Kconfig.64: Now that we created all the new custom board files, we have to modify the arch Kconfig, arch/arm/mach-rmobile/Kconfig.64, to include your board:
[...]
config TARGET_SMARC_RZG2LC
bool "RZ/G2LC SMARC board"
help
Support for Renesas RZ/G2LC Dev Platform
+config TARGET_MY_CUSTOM_BOARD
+ bool "RZ/G2L my stunning custom board"
+ help
+ This is a test custom board with RZ/G2L
+
endchoice
config SYS_SOC
default "rmobile"
[...]
source "board/renesas/ulcb/Kconfig"
source "board/beacon/beacon-rzg2m/Kconfig"
source "board/renesas/rzg2l-dev/Kconfig"
source "board/renesas/rzv2l-dev/Kconfig"
source "board/renesas/rzg2lc-dev/Kconfig"
+source "board/<vendor>/my_custom_board/Kconfig"
8) Make deconfig: Now we have to create the default configuration, assuming we want to use the .out as output directory:
make <vendor>_my_custom_board_defconfig O=.out
Configuration
SoC: RZ/G2E, RZ/G2N, RZ/G2M, RZ/G2H
Content: TBD
SoC: RZ/G2L, RZ/V2L
Regarding u-boot configuration, similarly to the Linux kernel U-boot can be configured by giving the following command:
make menuconfig O=.out
You can search by typing "/" (slash). Typing the string you want, you can see from the search results the key (number) you need to press to redirect you to the specified menu.
Firstly, you need to change the default fdt file (search DEFAULT_FDT_FILE) to reflect the board name:
And select your custom board as target (search MY_CUSTOM_BOARD):
Select also my_custom_board as default device tree (search DEFAULT_DEVICE_TREE):
In general this is how you can opt in and out any u-boot feature. For example let's assume we also want to enable QSPI support for your custom board, similarly to what just done we have to make sure that all the following features are enabled:
SPI_FLASH SPI_FLASH_BAR SPI_FLASH_USE_4K_SECTORS SPI DM_SPI SPI_FLASH_WINBOND RENESAS_RPC_SPI CMD_SF CMD_SPI SPI_FLASH_STMICRO DM_SPI_FLASH
Once you're happy with the configuration changes, exit and save your changes, when you asked, and then go on an save your configuration file:
make savedefconfig O=.out cp .out/defconfig configs/<vendor>_my_custom_board_defconfig
u-boot environment variables
In the configuration it is also possible to specify some options about environment variables:
CONFIG_ENV_IS_IN_MMC=y CONFIG_SYS_MMC_ENV_DEV=0 CONFIG_SYS_MMC_ENV_PART=2 CONFIG_ENV_SIZE=0x20000 CONFIG_ENV_OFFSET=0xFFFE0000
CONFIG_SYS_MMC_ENV_DEV: It specifies which MMC device has to be used to store the environment variables;
CONFIG_SYS_MMC_ENV_PART: which MMC area (0=user, 1=boot 1, 2=boot 2);
CONFIG_ENV_SIZE: as the name suggests, size;
CONFIG_ENV_OFFSET: this is the offset in the partition chosen, a negative value is treated as a backwards offset from the end of the eMMC device/partition, rather than a forwards offset from the start.
Note that it is also possible to store them into other memories, e.g QSPI.
Device
treeTree
File Location
- Like the Linux kernel, u-boot uses a Device Tree to configure device. The Device Tree for the u-boot is supposed to use the same names and syntax as the kernel to make them as compatible as possible.
- The location for the Device Tree .dts files are: arch/arm/dts/
Adding Your Own Device Tree to the Build
- When porting u-boot to your own board, you should create your own Device Tree File (.dts).
- To start, simply copy a Device Tree file (.dts) file for a Renesas evaluation with the same device on your board. For example:
cp arch/arm/dts/smarc-rzg2l.dts arch/arm/dts/my_custom_board.dts
- Once you've copied/renamed and created your new .dts file, you will need to add it to the Makefile in the arch/arm/dts/ directory.
- arch/arm/dts/Makefile
- The Renesas RZ device are in the group CONFIG_RCAR_GEN3. You if you search for that name, you will find all the Device Trees for all the Renesas evaluation boards.
- To add your new .dts board, you can simple add this line anywhere in the file. (This is the recommended way)
dtb-$(CONFIG_RCAR_GEN3) += my_custom_board.dts
- Another option is to add simply add your new file to the current list of Renesas files. (alternative option). Remember you need a backslash \ at the end of the previous line.
[...] rzg2lc-dev.dtb \ - smarc-rzg2lc.dtb + smarc-rzg2lc.dtb \ + my_custom_board.dtb ifdef CONFIG_RCAR_GEN3 [...]
Selecting your Device Tree as the Default to Use
- By adding your .dts file to the Makefile, it simply compiles the .dts file into a binary (also called a Flattened Device Tree Blob, .dtb)
- The u-boot image you load into your board is a combination for u-boot.bin + .dtb (a single binary).
- You select the Device Tree Blob you want to append during the build by setting DEFAULT_FDT_FILE and DEFAULT_DEVICE_TREE in u-boot configuration as explained in the previous section.
SoC: RZ/G2E, RZ/G2N, RZ/G2M, RZ/G2H
Content: TBD
SoC: RZ/G2L, RZ/V2L
Apart from features that can be enabled/disabled using menuconfig, another very common thing you may need to touch is the device tree, in a similar fashion you would do for the Linux kernel.
Here below an example on how your custom device tree should be modified to enable the SPI Multi I/O Bus Controller (aka RPC) in the RZ/G2L BSP v1.3 that does not officially support it. Newer versions may have these changes already implemented but the example per se is still valid.
The device trees are stored in the folder arch/arm/dts. In this example we have to modify my_custom_board.dts (patch style) as per below:
[...]
aliases {
serial0 = &scif0;
+ spi0 = &spibsc;
};
[...]
+&spibsc {
+ num-cs = <1>;
+ status = "okay";
+ spi-max-frequency = <40000000>;
+ #address-cells = <1>; + #size-cells = <0>;
+
+ flash0: spi-flash@0 {
+ #address-cells = <1>;
+ #size-cells = <1>;
+ compatible = "spi-flash", "jedec,spi-nor";
+ spi-max-frequency = <40000000>;
+ spi-tx-bus-width = <1>;
+ spi-rx-bus-width = <1>;
+ reg = <0>;
+ status = "okay";
+ };
+};
[...]
Source code modification
SoC: RZ/G2E, RZ/G2N, RZ/G2M, RZ/G2H
Content: TBD
SoC: RZ/G2L, RZ/V2L
Sometimes, but not very often, you may need to modify u-boot source code, maybe to modify an existing driver. Following the same example as the previous section, in order to get the QSPI working we have to modify the RPC driver (drivers/spi/renesas_rpc_spi.c) and add a line for RZ/G2L:
[...]
{ .compatible = "renesas,rpc-r8a77995" },
{ .compatible = "renesas,rpc-r7s72100" },
+ { .compatible = "renesas,r9a07g044l-spibsc" },
{ }
};
[...]
u-boot environment variables
Among many other other parameters, u-boot default environment variables can be configured in the already mentioned:
include/configs/my_custom_board.h
CONFIG_EXTRA_ENV_SETTINGS and CONFIG_BOOTCOMMAND are what you might want to customize.
Building and
debuggingDebugging
SoC: RZ/G2E, RZ/G2N, RZ/G2M, RZ/G2H
Content: TBD
SoC: RZ/G2L, RZ/V2L
Regarding build, firstly have a look here.
Once happy with the modifications (configuration, device tree, source code) described in the previous sections, to build u-boot simply:
make -j$(nproc) O=.out
The binaries will be located in the .out folder and u-boot.bin is the file you want to combine with bl31.bin using the fip tool, please refer to this section.
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