[Country EMBED strategy] [117] [LED driver Design]

LED programming

1. Writing kernel modules

2. Build a character-driven framework

3. Implement the Device method

Header file

<linux/io.h>

Writel ()

Leddev.h

// Device Commands #define Led_magic ' L '               //LED magic number #define led_on  _io (led_magic, 0)   //  Turn on LED#define led_off _io (led_magic, 1)   // turn off led

Leddev.c

/********************************************************************* Header File ************************************ *********************************/#include<linux/init.h>#include<linux/module.h>#include<linux/cdev.h>#include<linux/fs.h>#include<linux/io.h>#include"leddev.h"/********************************************************************* Macro Definition ************************************ *********************************/#defineGpbcon 0x56000010//Control Register#defineGpbdat 0x56000014//Data Registers/********************************************************************* global variable *********************************** **********************************/structCdev Chrdev;//character Devicedev_t Devnum;//Main device numberunsignedint*ledcon;//Control RegisterUnsignedint*leddat;//Data Registers/********************************************************************* Device Method ********************************** ***********************************///turn on the LEDintLed_open (structInode *node,structFile *Filp) {    //Configuring the LED pinLedcon = Ioremap (Gpbcon,4);//Virtual Address TranslationWritel (0x00015400, Ledcon);//gpbcon[17:10]:01010101//setting the LED statusLeddat = Ioremap (Gpbdat,4);//Virtual Address TranslationWritel (0x00000140, Leddat);//gpbdat[8:5]:1010        return 0;}//Turn off LEDintLed_close (structInode *node,structFile *Filp) {    return 0;}//Control ledLongLed_ioctl (structFile *filp, unsignedintCMD, unsignedLongArg) {    //Processing Commands    Switch(cmd) { CaseLED_ON://turn on the LEDWritel (0x00000000, Leddat);//gpbdat[8:5]:0000             Break;  CaseLed_off://Turn off LEDWritel (0x000001e0, Leddat);//gpbdat[8:5]:1111             Break; default:            return-EINVAL; }        return 0;}//led MethodstructFile_operations Led_fops ={. Open=Led_open,. Release=led_close,. Unlocked_ioctl=Led_ioctl};/********************************************************************* Module Installation *********************************** **********************************///Loading ModulesStatic intLed_init () {//registering the device structureCdev_init (&chrdev, &led_fops); //registering a master device numberAlloc_chrdev_region (&devnum,0,1,"myled"); //Add Device StructureCdev_add (&chrdev, Devnum,1); return 0;}//Uninstalling the moduleStatic voidLed_exit () {//Unregister device StructureCdev_del (&Chrdev); //Unregister the main device numberUnregister_chrdev_region (Devnum,1);}/********************************************************************* Module Declaration *********************************** **********************************/Module_license ("GPL"); Module_author ("D"); Module_description ("myled"); Module_version ("v1.0"); Module_init (Led_init); Module_exit (led_exit) ;

Ledapp.c

#include <stdio.h>#include<sys/types.h>#include<sys/stat.h>#include<fcntl.h>#include<sys/ioctl.h>#include<unistd.h>#include"leddev.h"intMainintargcChar**argv) {    //parameter Detection    if(ARGC! =2) {printf ("usage:\n\t%s <state>\n", argv[0]); return-1; }        //turn on the device    intFD; FD= Open ("/dev/myled0", O_RDWR); //Control Equipment    intState ; State= Atoi (argv[1]); if(state) {//turn on the LEDIOCTL (FD, led_on); }Else{//Turn off LEDIOCTL (FD, Led_off); }        //turn off the deviceClose (FD); return 0;}

[Country EMBED strategy] [117] [LED driver Design]