It is actually very simple to transplant the driver of Feiling embedded i.MX8MP development board

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It is actually very simple to transplant the driver of Feiling embedded i.MX8MP development board [Copy link]

Engineers may need to transplant drivers when developing the Feiling embedded OKMX8MP-C development board . To prevent users from affecting the development progress due to not understanding the process of transplanting drivers, today I will take writing a hello driver as an example to demonstrate the process of transplanting drivers. Friends who have needs can refer to this method to operate by themselves.

01

Enter the drivers directory of the source code and create a directory called hello:

forlinx@ubuntu:~$  cd  /home/forlinx/work/OK8MP-linux-sdk/OK8MP-linux-kernel/driversforlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers$mkdir  hello

02

Enter the hello directory and create hello.c:forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers$ cd helloforlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$ vi hello.c

Write the following content in hello.c:

#include  <linux/init.h>#include  <linux/module.h>static  int hello_init(void){printk(KERN_ALERT  "Hello world\n");return  0;}static  void hello_exit(void){printk(KERN_ALERT  "Goodbye world\n");}module_init(hello_init);module_exit(hello_exit);MODULE_LICENSE("Dual  BSD/GPL");

Program meaning: insmod driver prints Hello world when mounted, rmmod driver prints Goodbye world when uninstalled

03

Create two files, Kconfig and Makefile, in this folder.

forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$  vi  Kconfig

Write the following content in the Kconfig file:

config  HAVE_HELLOtristate       "hello driver"helpThis  hello  driver  is  just  to  show  how  to  develop  driver  process.

This  driver  can  also  be  built  as  a  module.  If  so,  the  module will  be  called  .default  y#endmenu

This means that if CONFIG_HAVE_HELLO is enabled, the hellodrivers menu will be displayed in the kernel trimming configuration file and compiled into the kernel by default:

y: compile into the kernel

m: compile to module .ko file

n: indicates not to compile and not to enable.

forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$  vi  Kconfig

Write the following content in the Makefile:

obj-$(CONFIG_HAVE_HELLO)        +=      hello.o

Notice:

The name of the macro definition should be the same as that in Kconfig. Add the file name to be compiled at the end. Because the kernel will automatically add the prefix CONFIG, we also need to add CONFIG_ in front of the name here, indicating that when CONFIG_HAVE_HELLO is enabled, the file specified by the compilation rule is hello.c.

Give the three added files permissions:

forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$  chmod  777 hello.cforlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$  chmod  777 Kconfigforlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$  chmod  777 Makefile

04

Edit the top-level Kconfig and Makefile files of drivers.

forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers/hello$  cd  ..forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers$  vi Kconfig

Write the following content in the Kconfig file:

source  "drivers/counter/Kconfig"source  "drivers/mxc/Kconfig"source  "drivers/hello/Kconfig"    //在endmenu前添加hello文件夹的配置文件解析endmenu

In this way, the configuration system will parse the Kconfig in the hello folder according to this configuration.

Edit the Makefile:

forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers$  vi Makefile

Write the following content in the Makefile:

obj-$(CONFIG_COUNTER)           += counter/obj-y                           += mxc/obj-$(CONFIG_HAVE_HELLO)        +=      hello/     //在Makefile最后加入这一句

The purpose of this sentence is to find the source file when CONFIG_HAVE_HELLO is enabled. Combined with the module Makefile under the hello file, a hierarchical Makefile is formed. Note that the / is not missing. Adding the name of the custom folder here means compiling this folder into the kernel.

5

Start compiling:

forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/drivers$  cd ../..forlinx@ubuntu:~/work/OK8MP-linux-sdk$  .  /opt/fsl-imx-xwayland/5.4-zeus/environment-setup-aarch64-poky-linuxforlinx@ubuntu:~/work/OK8MP-linux-sdk$  .  environment-setup-aarch64-poky-linuxforlinx@ubuntu:~/work/OK8MP-linux-sdk$  cd  OK8MP-linux-kernelforlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel$  make modulesscripts/kconfig/conf --syncconfig Kconfigdrivers/hello/Kconfig:7:warning:  ignoring unsupported character ''drivers/hello/Kconfig:7:warning:  ignoring unsupported character ''drivers/hello/Kconfig:7:warning:  ignoring unsupported character ''drivers/hello/Kconfig:7:warning:  ignoring unsupported character ''** Restart config...*** Device Drivers*Trust the bootloader  to initialize Linux's CRNG (RANDOM_TRUST_BOOTLOADER) [N/y/?] nPlatform support for  Chrome hardware (transitional) (MFD_CROS_EC) [Y/n/m/?] yTrusted Execution  Environment support (TEE) [Y/n/m/?] yhello driver  (HAVE_HELLO) [Y/n/m/?] (NEW) m    //将hello驱动编译进内核就配置为mCALL   scripts/checksyscalls.shCALL   scripts/atomic/check-atomics.shCHK      include/generated/compile.hGZIP   kernel/config_data.gzCC     kernel/configs.o[…]LD      vmlinuxSORTEX  vmlinuxSYSMAP  System.mapBuilding modules,  stage 2.MODPOST 536 modulesCC [M] drivers/hello/hello.mod.oLD [M] drivers/hello/hello.ko

After the compilation is complete, you can see the compiled driver in the OK8MP-linux-kernel/drivers/hello directory:

forlinx@ubuntu:~/work/OK8MP-linux-sdk/OK8MP-linux-kernel/$  ls drivers/hellohello.c  hello.ko  hello.mod  hello.mod.c  hello.mod.o  hello.o  Kconfig  Makefile modules.order

6

Copy hello.ko to the development board using a USB flash drive or TF card for verification:

rootK8MP:~#cd/run/media/sda1///进入U盘的路径下root@OK8MP:/run/media/sda1#insmodhello.ko//挂载hello.ko[138.679964]Helloworld          //挂载驱动打印信息root@OK8MP:/run/media/sda1#rmmodhello.ko//卸载hello.ko[142.022115]Goodbyeworld //卸载驱动打印信息root@OK8MP:/run/media/sda1#

From the above test, we can see that the hello.ko driver can run normally.

The above is the process of writing and adding a driver by yourself, which I demonstrated to you. If you want to transplant a certain module, you can ask the module manufacturer for the ready-made driver .c file, and then configure Makefile and Kconfig according to the above steps.

lugl4313820

Should this compilation be compiled together with the firmware, or should it be compiled separately? If it is compiled in full, will it take a long time?

hades2015

Thanks for sharing, I learned a lot!!

通途科技

Thanks for sharing, I learned a lot, very good content, keep it up! ! ! !