Linux Kernel 4.19+内核使用GPIO模拟I2C的方法

1.修改内核配置文件，使内核支持GPIO模拟I2C

//开启方式
make menuconfig
Device Drivers --->
	<*> I2C support  --->
		I2C Hardware Bus support  ---> 
			<*> GPIO-based bitbanging I2C

2.对应的dts里面增加GPIO模拟I2C的设备树

注意头文件：#include <dt-bindings/gpio/gpio.h>
	i2c@0 {
		compatible = "i2c-gpio";
		sda-gpios = <&gpio_chip16 3 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
		scl-gpios = <&gpio_chip16 4 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
		i2c-gpio,delay-us = <2>;	/* ~100 kHz */
		#address-cells = <0>;
		#size-cells = <0>;
	};

编译后烧写，会发现/dev下多了一个i2c总线，多出来的那个就是了。