...
Versatility: U-Boot is designed to be versatile and can be adapted to various architectures, including ARM, MIPS, x86, and more.
Open Source: U-Boot is released under the GNU General Public License (GPL), providing users with the freedom to view, modify, and distribute the source code.
Boot Sequence Control: U-Boot handles the initialization and configuration of the hardware during the boot process. It allows users to interact with the bootloader through a command-line interface, enabling them to control the boot sequence, load kernel images, and set various parameters.
Support for Various Storage Devices: U-Boot supports loading firmware and kernel images from a variety of storage devices, including NAND and NOR flash memory, SD cards, USB storage, TFTP servers, and more.
Environment Variables: U-Boot allows the configuration of environment variables that store important settings, such as boot parameters and memory addresses.
Network Booting: U-Boot supports network booting, allowing systems to load kernel images and other files over the network using protocols like TFTP or NFS.
Development and Debugging Tools: U-Boot includes tools for debugging and development, such as memory and register inspection, script execution.
Features of U-Boot of SP7350
...
Platform
U-Boot serves as the second-stage bootloader in SP7350 platform. After initializing itself, U-Boot then loads Linux kernel image from external storage devices into DRAM and executes it. As it runs in DRAM, its size is no longer limited by SRAM of SP7350 (only limited by the system's DRAM size), ranging from hundreds of kilobytes to several megabytes.
...
Support console at UART0 (@ 115,200 bps).
Support booting Linux from SPI-NOR flash, SPI-NAND flash, 8-bit NAND flash or eMMC device.
Support in-system program (ISP) for SPI-NOR flash, SPI-NAND flash, 8-bit NAND flash or eMMC device.
Support read images from USB flash drives or SD cards for in-system program (ISP).
Support secure-boot (check hash value of Linux image).
Support fastboot function for eMMC device.
Support fastboot function for SPI-NAND and 8-bit NAND flashes (only for updating Linux kernel or rootfs partition).
Supported
...
Drivers for SP7350
...
Platform
The source files of U-Boot are conveniently located within the "boot/uboot/" directory under the project's top directory. For the SP7350 platform, a wide array of device drivers is supported. These drivers are within the "drivers" directory. Below is a reference table detailing the drivers along with their corresponding feature descriptions:
Drivers | Folders or files | Feature descriptions |
8-bit NAND | mtd/nand/raw/sp_paranand/ |
|
Clock | clk/sunplus/ |
|
eMMC | mmc/sp_mmc* |
|
Ethernet | net/designware.* |
|
I2C | i2c/designware_i2c* |
|
OTP | soc/sunplus/ |
|
Reset | reset/reset-sunplus.c |
|
Pinctrl | pinctrl/sunplus/ |
|
SD card | mmc/sp_sd* |
|
SPI | spi/designware_spi.c |
|
SPI-NAND | mtd/nand/raw/sp_* |
|
SPI-NOR | mtd/spi/spi-nor-ids.c spi/sp_spi_nor.c |
|
UART | serial/serial_sunplus.c |
|
USB2.0 EHCI | usb/host/ehci-sunplus.c |
|
USB2.0 OHCI | usb/host/ohci-sunplus.c |
|
USB2.0 UDC | usb/gadget/sp_udc.c |
|
USB3.0 DRD | usb/host/xhci-spdwc3.c usb/gadget/spdwc3_udc.c |
|
Video | video/sunplus/sp7350/disp/ |
|
SP7350
...
Platform-specific
...
Files or
...
Folders
Board-specific
...
Files
Board-specific files for the SP7350 platform can be found in the “board/sunplus/” directory. Below is a breakdown of the folders and their descriptions:
Folders | Descriptions |
common/secure_sp7350/ | Contains files related to secure boot functionality. |
sp7350/ | Houses SP7350 platform-specific or hardware-specific files. |
Architecture-specific
...
Files
Architecture-specific files for the SP7350 platform are situated at “arch/arm/” within the U-Boot directory. Here's a summary of the files and folders:
Files or folders | Descriptions |
cpu/armv8/ | Contains ARMv8 CPU (ex: Cortex A55) related files. |
mach-pentagram/include/mach | Contains platform or hardware-related header files. |
mach-pentagram/cpu.c | Encompasses subroutines responsible for CPU reset, memory mapping, DRAM configuration, and more. |
Configuration
...
Header File
The configuration header file comprises board-specific configuration options, hardware parameters, and initialization settings tailored to the target platform. For the SP7350 platform, the configuration header file is “include/configs/pentagram_common_sp7350_c.h.”
Default
...
Configuration Files
Default configuration files of U-Boot are stored in the “configs” directory. Specifically for the SP7350 platform, default configuration files are prefixed with “sp7350_”.
Device-tree
...
Source Files
U-Boot shares device-tree source files with Linux, which are located in the directory 'linux/kernel/arch/arm64/boot/dts/sunplus/'.
U-Boot
...
Log and
...
Explanation
Line 1: The banner (version) of U-Boot.
...