RK3399使用微雪电子ST7735显示屏

1. 配置
   1.1 在内核中， make ARCH=arm64 menuconfig

-> Device Drivers 
     【*】 Staging drivers
     	【*】 Support for small TFT LCD display modules 
       			<M> FB driver for the ST7735R LCD Controller
       			<M> Module to for adding FBTFT devices

1.2 修改， kernel/drivers/staging/fbtft/Makefile

1.3 引脚配置， kernel/drivers/staging/fbtft/fbtft_device.c

1.4 设备树， kernel/arch/arm64/boot/dts/rockchip/rk3399-nanopi4-common.dtsi

kernel/arch/arm64/boot/dts/rockchip/rk3399.dtsi

2. 硬件连接

ST7735	NanoPi M4 (RK3399) 40-Pin GPIO1引脚定义
VCC	VCC3V3_SYS (Pin 1)
GND	GND (Pin 9)
DIN	SPI1_TXD (Pin 19)
CLK	SPI1_CLK (Pin 23)
CS	SPI1_CSn0 (Pin 24)
DC	GPIO1_A1 (Pin 11)
RST	GPIO1_C6 (Pin 16)
BL	GPIO1_A4 (Pin 15)

3. 驱动加载
   按顺序加载驱动
   1. insmod fbtft.ko
   2. insmod fbtft_device.ko name=adafruit18 busnum=1 rotate=270
   3. insmod fb_st7735r.ko
      驱动加载完成后生成设备