使能客户所需串口驱动（例如ch340）

修改/kernel/arch/arm64/configs/rockchip_defconfig文件，添加CONFIG_USB_SERIAL_CH341=y将ch340驱动编译进内核

android固定USB串口设备端口号

采用打补丁的方式修改/kernel/drivers/usb/serial/usb-serial.c文件。

参考链接：https://wenku.baidu.com/view/c6a00d1240323968011ca300a6c30c225901f02b.html

通过USB设备名去识别USB转串口插入的哪个U口，再根据不同的U口分配一个不同的节点。

static int allocate_minors(struct usb_serial *serial, int num_ports)

{

struct usb_serial_port *port;

unsigned int i, j;

int minor;

dev_dbg(&serial->inte**ce->dev, "%s %d\n", __func__, num_ports);

mutex_lock(&table_lock);

for (i = 0; i < num_ports; ++i) {

port = serial->port[i];

minor = idr_alloc(&serial_minors, port, 0, 0, GFP_KERNEL);

//固定USB转串口设备名

if(!strcmp(dev_name,"5-1"))

{

minor=1;

}

else if(!strcmp(dev_name,"7-1.1"))

{

minor=2;

}

else if(!strcmp(dev_name,"7-1.2"))

{

minor=3;

}

if (minor < 0)

goto error;

port->minor = minor;

port->port_number = i;

}

serial->minors_reserved = 1;

mutex_unlock(&table_lock);

return 0;

error:

/* unwind the already allocated minors */

for (j = 0; j < i; ++j)

idr_remove(&serial_minors, serial->port[j]->minor);

mutex_unlock(&table_lock);

return minor;

}

 

static int usb_serial_probe(struct usb_inte**ce *inte**ce,

       const struct usb_device_id *id)

{

...内容省略...

if (allocate_minors(serial, num_ports)) { 

替换为

if (allocate_minors(serial, num_ports,dev_name(&port->serial->dev->dev))) {

dev_err(ddev, "No more free serial minor numbers\n");

goto probe_error;

}

...内容省略...

}

配置环境变量

source build/envsetup.sh

lunch rk3399_all-userdebug

单独编译内核文件。

./mklinux.sh

打包镜像烧写文件。

./mkimage.sh

将/kernel/rockdev/Image-rk3399_all/boot.img分区烧写到开发板。