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