Rock3/extlinux
Contents
Common Hardware Interfaces, I2C, PWM, SPI, UART, CAN, etc
This page teaches how to enable overlays in file /boot/extlinux/extlinux.conf. The directory /dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/ includes overlays you can enable, to enable overlay, we just need add an absolute path of overlay after the key word fdtoverlays, there is a space between each overlay and a space between fdtoverlays and overlay's absolute path, for example,
fdtoverlays /dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/rk3568-fiq-debugger-uart2m0.dtbo /dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/rk3568-disable-npu.dtbo /dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/rk3568-spi3-m1-cs0-spidev.dtbo
The examples above indicates that rk3568-fiq-debugger-uart2m0 and rk3568-disable-npu and rk3568-spi3-m1-cs0-spidev and are enabled
To enable I2C, PWM, SPI, UART, CAN, etc, please see RK3566/RK3568 Available Overlay (ROCK 3A, ROCK 3B, Radxa CM3) part of Device Tree Overlays
I2C
To enable I2C-3 (/dev/i2c-3), add item "/boot/dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/rk3568-i2c2-m0.dtbo" to the "fdtovlays " line.
fdtoverlays /boot/dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/rk3568-i2c3-m0.dtbo
PWM
PWM0
Option 1: PWM0-M0
To enable PWM0-M0, add item "/boot/dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/rk3568-pwm0-m0.dtbo" to the "fdtoverlays " line.
fdtoverlays /boot/dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/rk3568-pwm0-m0.dtbo
The related directory /sys/devices/platform/fdd70000.pwm/pwm/pwmchip* will be created.
And you can do the operation in the directory.
Option 2: PWM0-M1
To enable PWM0-M0, add item "/boot/dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/rk3568-pwm0-m1.dtbo" to the "fdtoverlays " line.
fdtoverlyas /boot/dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/rk3568-pwm0-m1.dtbo
The related directory /sys/devices/platform/fdd70000.pwm/pwm/pwmchip* will be created.
SPI
To enable spi3 (/dev/spidev3.0), add item "/boot/dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/rk3568-spi3-m0-cs0-spidev.dtbo" to the "fdtovlays " line.
fdtoverlays /boot/dtbs/4.19.193-53-rockchip-gc36f859f0a63/rockchip/overlay/rk3568-spi3-m0-cs0-spidev.dtbo
UART
System default enable uart2-m0 (/dev/ttyS2) to be debug console.
overlays=rk3568-fiq-debugger-uart2m0
If you want to enable uart2-m0 (/dev/ttyS2) to be normal console, modify item "rk3568-uart2-m0" to the "overlays=" line.
overlays=rk3568-uart2-m0
CAN
I2C
PWM
SPI
UART
CAN