How to boot using device tree

Table of Contents Bootloader Configuration Kernel Configuration Device Tree

Bootloader Configuration

• Use these config.txt parameters:

 device_tree=bcm2835.dtb
 device_tree_address=0x100
 kernel_address=0x8000
 disable_commandline_tags=1
 init_uart_baud=115200
 init_uart_clock=3000000
 init_emmc_clock=50000000

Kernel

• Build a kernel from lp0/rpi-linear
• Copy arch/arm/boot/zImage to kernel.img
• Run make dtbs

Configuration

 Device Drivers
 |- Character devices
 |  `- Serial drivers
 |     `- ARM AMBA PL011 serial port support
 |        `- Support for console on AMBA serial port
 |- I2C support
 |  `- I2C Hardware Bus support
 |     `- BCM2708 BSC
 |- SPI support
 |  `- BCM2708 SPI controller driver (SPI0)
 |- GPIO Support
 |  `- Broadcom VideoCore Doorbell Support
 |- Watchdog Timer Support
 |  `- BCM2708 Watchdog
 |- Voltage and Current Regulator Support
 |  `- Broadcom VideoCore regulator
 |- Graphics support
 |  |- Support for frame buffer devices
 |  |  `- BCM2708 framebuffer support
 |  `- Bootup logo
 |     `- 224-color Raspberry Pi logo
 |- DMA Engine support
 |  `- BCM2708 DMA support
 |- MMC/SD/SDIO card support
 |  `- SDHCI platform and OF driver helper
 `- Broadcom BCM2708 SDHCI support
    `- DMA support on BCM2708 SDHCI

Device Tree

• Until Issue #24 is completed you need to manually configure the device tree file
  • Using ftdput from git://git.jdl.com/software/dtc.git:

 fdtput arch/arm/boot/bcm2835-rpi-b.dtb /system revision 2
 fdtput -t x arch/arm/boot/bcm2835-rpi-b.dtb /system serial 0 0
 fdtput -t hhx arch/arm/boot/bcm2835-rpi-b.dtb /axi/usb/hub/ethernet mac-address 02 00 00 00 00 00
 fdtput arch/arm/boot/bcm2835-rpi-b.dtb /display broadcom,width 1920
 fdtput arch/arm/boot/bcm2835-rpi-b.dtb /display broadcom,height 1200
 fdtput arch/arm/boot/bcm2835-rpi-b.dtb /display broadcom,depth 16
 fdtput -t x arch/arm/boot/bcm2835-rpi-b.dtb /axi/dma broadcom,channels 783c

• • If you want to use 192MB instead of the default 128MB:

 (echo -ne "\x00\x00\x00\x00\x0c\x00\x00\x00"; echo -e "\x00\x00\x00\x00\x04\x00\x00\x00") \
 | dd conv=notrunc bs=8 count=2 seek=5 of=arch/arm/boot/bcm2835-rpi-b.dtb

• Copy arch/arm/boot/bcm2835-rpi-b.dtb to bcm2835.dtb