Linux driver programming - ch340x driver transplantation

Evans_li

Linux driver programming - ch340x driver transplantation [Copy link]

Linux driver programming - ch340x driver transplantation

Key concepts:

ch340x driver transplantation

As a universal device, manufacturers provide drivers for various platforms. Linux usually provides driver source code.

Generally speaking, driver transplantation means modifying the manufacturer's driver source code and compiling it into a driver that is compatible with your own system version.

Introduction to ch340

USB to serial port chip, you need to write a driver.

Purpose:

Transplant, compile and load the official ch34x driver to realize the USB to serial port function.

Hardware circuit:

Development board, a CH340 module.

Driver source code download:

Download address: http://www.wch.cn/download/CH341SER_LINUX_ZIP.html

Here I choose Linux driver

CH341SER_LINUX.ZIP contains three files

ch34x.c ch34x driver source code

Makefile Compilation

readme.txt Some version and command descriptions

Code:

We mainly modify two places in ch34x.c

Comment out the following two lines

Modify the Makefile. I did not use the built-in Makefile, but wrote my own.

KERNELDIR := /home/sixer/imx_kernel/linux-imx-rel_imx_4.1.15_2.1.0_ga
CURRENT_PATH := $(shell pwd)

export ARCH=arm
export CROSS_COMPILE=arm-linux-gnueabihf-

target := ch34x
obj-m := $(target).o
APP_NAME := $(target)_app

build: kernel_modules

kernel_modules:
    $(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) modules

clean:
    $(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) clean
#   rm -rf $(APP_NAME)

dir_exist = $(shell if [ -d "/nfsroot/$(target)/" ]; then echo "exist"; else echo "noexist"; fi)
$(info $(dir_exist))

install:
ifeq ("$(dir_exist)", "noexist")
    $(shell mkdir /nfsroot/$(target))
    #"The folder does not exist and has been recreated"
endif
#   arm-linux-gnueabihf-gcc $(APP_NAME).c -o  $(APP_NAME)
    cp *.ko /nfsroot/$(target)/

Compile and run:

makeCompile

Generate target filech34x.ko

make installCopy the target to the NFS directory

Plug in my ch340 module

insmod ch34x.koLoad ch34x driver

Experimental phenomenon:

[root@iTOP-iMX6UL]# cd /mnt/nfs_dir/ch34x/
[root@iTOP-iMX6UL]# ls
ch34x.ko
[root@iTOP-iMX6UL]# insmod ch34x.ko
usbcore: registered new interface driver ch34x
usbserial: USB Serial support registered for ch34x
[root@iTOP-iMX6UL]# usb 2-1.3: new full-speed USB device number 4 using ci_hdrc
ch34x 2-1.3:1.0: ch34x converter detected
usb 2-1.3: ch34x converter now attached to ttyUSB0

[root@iTOP-iMX6UL]# 

Summarize:

After loading the ch34x driver and plugging in the module, the system immediately recognized a serial port, indicating that my transplantation was successful.

WeChat ID:

InsertingAll

digital2Fox

ch340 should have supported it a long time ago

MianQi

I want to give this a try. I communicated with Qinheng’s technical staff several times half a year ago, but to no avail.

MianQi

Just identifying a USB port may not mean that the transplantation is successful. You need to try actual serial port communication.

freebsder

The ch34x driver is already supported by the official Linux code, it seems to be under driver/usb/serial.

mypc16888

This is good, I will test it to see if it works. Thanks for sharing

w494143467

This should be the installation of the ch34x driver, it cannot be called a transplant!