linux驱动开发FL2440开发板-LED驱动及其测试程序

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1.1vim编写LED驱动代码

[leiyuxing@centos6 ~]$ mkdir LED[leiyuxing@centos6 LED]$ vim s3c_led

/**********************************************************************************      Copyright:  (C) 2016  leiyuxing <leiyuxing@gmail.com>*                  All rights reserved.**       Filename:  s3c_led.c*    Description:  This file**        Version:  1.0.0(07/25/2016~)*         Author:  leiyuxing <leiyuxing@gmail.com>*      ChangeLog:  1, Release initial version on "07/25/2016 16:46:40 PM"*********************************************************************************/
#include <linux/module.h>   /* Every Linux kernel module must include this head */
#include <linux/init.h>     /* Every Linux kernel module must include this head */
#include <linux/kernel.h>   /* printk() */
#include <linux/fs.h>       /* struct fops */
#include <linux/errno.h>    /* error codes */
#include <linux/cdev.h>     /* cdev_alloc()  */
#include <asm/io.h>         /* ioremap()  */
#include <linux/ioport.h>   /* request_mem_region() */#include <asm/ioctl.h>      /* Linux kernel space head file for macro _IO() to generate ioctl command  */
#ifndef __KERNEL__
#include <sys/ioctl.h>     /* User space head file for macro _IO() to generate ioctl command */
#endif
//#include <linux/printk.h> /* Define log level KERN_DEBUG, no need include here */#define DRV_AUTHOR                "leiyuxing  <leiyuxing@gmail.com>"
#define DRV_DESC                  "S3C24XX LED driver"#define DEV_NAME                  "led" //定义设备名称
#define LED_NUM                   4  //定义设备数量/* Set the LED dev major number */
//#define LED_MAJOR                 79
#ifndef LED_MAJOR
#define LED_MAJOR                 0   //定义主设备号为0，一般这个定义设备号是固定不可用的，但是 这为自动分配主设备号。#endif#define DRV_MAJOR_VER             1
#define DRV_MINOR_VER             0
#define DRV_REVER_VER             0#define DISABLE                   0//出现错误定义为0
#define ENABLE                    1//出现错误定义为1（两个错误这样定义应该是不同函数错误返回值不同）#define GPIO_INPUT                0x00//宏定义 GPIO输入模式用0代替
#define GPIO_OUTPUT               0x01//宏定义 GPIO输出模式用1代替#define PLATDRV_MAGIC             0x60  //魔术字
#define LED_OFF                   _IO (PLATDRV_MAGIC, 0x18)//_IO是Core_cm3.h中被重定义：#define     _IO     volatile的作用就是指示因优化而省略此指令
#define LED_ON                    _IO (PLATDRV_MAGIC, 0x19)#define S3C_GPB_BASE              0x56000010  //GPB基地址及偏移地址
#define GPBCON_OFFSET             0
#define GPBDAT_OFFSET             4
#define GPBUP_OFFSET              8
#define S3C_GPB_LEN               0x10        /* 0x56000010~0x56000020  */int led[LED_NUM] = {5,6,8,10};  /* Four LEDs use GPB5,GPB6,GPB8,GPB10 */static void __iomem *s3c_gpb_membase;  //定义iomem*类型变量#define s3c_gpio_write(val, reg) __raw_writel((val), (reg)+s3c_gpb_membase)//虚拟地址读取到物理地址
#define s3c_gpio_read(reg)       __raw_readl((reg)+s3c_gpb_membase)int dev_count = ARRAY_SIZE(led);  //设备总数
int dev_major = LED_MAJOR; //主设备
int dev_minor = 0;  //次设备
int debug = DISABLE;static struct cdev      *led_cdev;  //定义结构体指针
static int s3c_hw_init(void)   //初始化函数
{int          i;volatile unsigned long  gpb_con, gpb_dat, gpb_up;if(!request_mem_region(S3C_GPB_BASE, S3C_GPB_LEN, "s3c2440 led"))//判断是否成功申请一段内存空间{return -EBUSY;}if( !(s3c_gpb_membase=ioremap(S3C_GPB_BASE, S3C_GPB_LEN)) )//判断虚拟地址到物理地址的映射{release_mem_region(S3C_GPB_BASE, S3C_GPB_LEN);return -ENOMEM;}for(i=0; i<dev_count; i++){/* Set GPBCON register, set correspond GPIO port as input or output mode  */gpb_con = s3c_gpio_read(GPBCON_OFFSET);gpb_con &= ~(0x3<<(2*led[i]));   /* Clear the currespond LED GPIO configure register */gpb_con |= GPIO_OUTPUT<<(2*led[i]); /* Set the currespond LED GPIO as output mode */s3c_gpio_write(gpb_con, GPBCON_OFFSET);/* Set GPBUP register, set correspond GPIO port pull up resister as enable or disable  */gpb_up = s3c_gpio_read(GPBUP_OFFSET);//gpb_up &= ~(0x1<<led[i]); /* Enable pull up resister */gpb_up |= (0x1<<led[i]);  /* Disable pull up resister */s3c_gpio_write(gpb_up, GPBUP_OFFSET);/* Set GPBDAT register, set correspond GPIO port power level as high level or low level */gpb_dat = s3c_gpio_read(GPBDAT_OFFSET);//gpb_dat &= ~(0x1<<led[i]); /* This port set to low level, then turn LED on */gpb_dat |= (0x1<<led[i]);  /* This port set to high level, then turn LED off */s3c_gpio_write(gpb_dat, GPBDAT_OFFSET);}return 0;
}static void turn_led(int which, unsigned int cmd) //led函数的操作
{volatile unsigned long  gpb_dat;gpb_dat = s3c_gpio_read(GPBDAT_OFFSET);if(LED_ON == cmd){gpb_dat &= ~(0x1<<led[which]); /*  Turn LED On */}else if(LED_OFF == cmd){gpb_dat |= (0x1<<led[which]);  /*  Turn LED off */}s3c_gpio_write(gpb_dat, GPBDAT_OFFSET);
}static void s3c_hw_term(void) //清除led操作函数
{int                     i;volatile unsigned long  gpb_dat;for(i=0; i<dev_count; i++){gpb_dat = s3c_gpio_read(GPBDAT_OFFSET);gpb_dat |= (0x1<<led[i]);  /* Turn LED off */s3c_gpio_write(gpb_dat, GPBDAT_OFFSET);}release_mem_region(S3C_GPB_BASE, S3C_GPB_LEN); //释放I/O内存iounmap(s3c_gpb_membase);   //iounmap函数取消iounmap（）做的映射
}static int led_open(struct inode *inode, struct file *file)//led开启函数
{int minor = iminor(inode);   //获取次设备号file->private_data = (void *)minor;  //保存到一个全局变量printk(KERN_DEBUG "/dev/led%d opened.\n", minor);return 0;
}static int led_release(struct inode *inode, struct file *file)  //led关闭函数
{printk(KERN_DEBUG "/dev/led%d closed.\n", iminor(inode));return 0;
}static void print_help(void)      //帮助信息
{printk("Follow is the ioctl() commands for %s driver:\n", DEV_NAME);//printk("Enable Driver debug command: %u\n", SET_DRV_DEBUG);printk("Turn LED on command  : %u\n", LED_ON);printk("Turn LED off command : %u\n", LED_OFF);return;
}static long led_ioctl(struct file *file, unsigned int cmd, unsigned long arg)  //ioctl函数
{int which = (int)file->private_data; //接收次设备号switch (cmd)   //判断led开关{case LED_ON:turn_led(which, LED_ON);break;case LED_OFF:turn_led(which, LED_OFF);break;default:printk(KERN_ERR "%s driver don't support ioctl command=%d\n", DEV_NAME, cmd);print_help();break;}return 0;
}static struct file_operations led_fops =            //fops函数
{.owner = THIS_MODULE,.open = led_open,.release = led_release,.unlocked_ioctl = led_ioctl,
};static int __init s3c_led_init(void)         //init函数
{int                    result;dev_t                  devno;if( 0 != s3c_hw_init() )     //做初始化的判断{printk(KERN_ERR "s3c2440 LED hardware initialize failure.\n");return -ENODEV;}/*  Alloc the device for driver */if (0 != dev_major) /*  Static */     //静态分配主，次设备号转化为dev_t设备编号{devno = MKDEV(dev_major, 0);result = register_chrdev_region (devno, dev_count, DEV_NAME);}else{result = alloc_chrdev_region(&devno, dev_minor, dev_count, DEV_NAME);//动态分配主，次设备号dev_major = MAJOR(devno);}/*  Alloc for device major failure */if (result < 0)     //分配失败则打印{printk(KERN_ERR "S3C %s driver can't use major %d\n", DEV_NAME, dev_major);return -ENODEV;
}
printk(KERN_DEBUG "S3C %s driver use major %d\n", DEV_NAME, dev_major);if(NULL == (led_cdev=cdev_alloc()) ) //led_cddv分配失败打印{printk(KERN_ERR "S3C %s driver can't alloc for the cdev.\n", DEV_NAME);unregister_chrdev_region(devno, dev_count);return -ENOMEM;}led_cdev->owner = THIS_MODULE;  //分配成功，进行参数定义cdev_init(led_cdev, &led_fops);  //链接led_cdev和led_fopsresult = cdev_add(led_cdev, devno, dev_count);//添加内存if (0 != result)      //出错打印{printk(KERN_INFO "S3C %s driver can't reigster cdev: result=%d\n", DEV_NAME, result);goto ERROR;}printk(KERN_ERR "S3C %s driver[major=%d] version %d.%d.%d installed successfully!\n",DEV_NAME, dev_major, DRV_MAJOR_VER, DRV_MINOR_VER,DRV_REVER_VER);  //打印成功return 0;ERROR:                 //内存出错执行printk(KERN_ERR "S3C %s driver installed failure.\n", DEV_NAME);cdev_del(led_cdev);unregister_chrdev_region(devno, dev_count);return result;
}
static void __exit s3c_led_exit(void)     //led退出函数
{dev_t devno = MKDEV(dev_major, dev_minor);s3c_hw_term();      //调用清除led操作函数cdev_del(led_cdev);   //撤销unregister_chrdev_region(devno, dev_count);printk(KERN_ERR "S3C %s driver version %d.%d.%d removed!\n",DEV_NAME, DRV_MAJOR_VER, DRV_MINOR_VER,DRV_REVER_VER);return ;
}/* These two functions defined in <linux/init.h> */
module_init(s3c_led_init);
module_exit(s3c_led_exit);module_param(debug, int, S_IRUGO);
module_param(dev_major, int, S_IRUGO);MODULE_AUTHOR(DRV_AUTHOR);
MODULE_DESCRIPTION(DRV_DESC);
MODULE_LICENSE("GPL");

以上就是我们的LED相关驱动模块函数。

先是调用module_init函数，在调用s3c_led_init函数，这个函数会调用 s3c_hw_init进行初始化；接着s3c_led_init函数会进行分配主次设备号，按照传入的参数判断是动态分配或者是静态分配；再者是分配结构体，如果链接owner成功就可接着连接fops；然后是ON 和OFF的实现功能，使用ioctl与装入卸载次设备号驱动以及模块信息和fops中与主次设备号结构体链接，ioctl通过传参来实现相应的功能；最后进行撤销。

 1.2编写Makefile

[leiyuxing@centos6 LED]$ vim Makefile

C=/opt/buildroot-2012.08/arm920t/usr/bin/arm-linux-gcc
KDIR?=/home/leiyuxing/fl2440/kernel/linux-3.0
obj-m:=s3c_led.odefault:$(MAKE) -C $(KDIR) M=`pwd` modulesmake cleanclean:rm -f *.o *mod.c *.order *.symvers

make会生   .ko  文件 这就是我们所需要加载的驱动模块。

[leiyuxing@centos6 LED]$ lsMakefile  s3c_led.c  s3c_led.ko

2.1编写LED灯程序，点亮LED灯

[leiyuxing@centos6 LED_test]$ vim led_test.c

/**********************************************************************************      Copyright:  (C) 2016 leiyuxing <leiyuxing@gmail.com>*                  All rights reserved.**       Filename:  led_test.c*    Description:  This file*                 *        Version:  1.0.0(07/25/2016)*         Author:  leiyuxing  <leiyuxing@gmail.com>*      ChangeLog:  1, Release initial version on "07/25/2016 19:36:22 PM"*                 ********************************************************************************/#include <stdio.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdarg.h>
#include <errno.h>
#include <sys/types.h>
#include <fcntl.h>
#include <string.h>#define LED_NUM         4
#define DEVNAME_LEN     10#define PLATDRV_MAGIC             0x60
#define LED_OFF                   _IO (PLATDRV_MAGIC, 0x18)
#define LED_ON                    _IO (PLATDRV_MAGIC, 0x19)int main(int argc, char **argv)
{int fd[LED_NUM];int     i;int     j;char devname[DEVNAME_LEN] = {0};for(i = 0; i < LED_NUM; i++){snprintf(devname, sizeof(devname), "/dev/led%i",i);fd[i] = open(devname, O_RDWR,755);if(fd[i] < 0){printf("Can not open %s: %s", devname, strerror(errno));for(j = 0; j < i; j++){if(fd[j] > 0)close(fd[j]);}return -1;}}while(1){for(i = 0; i < LED_NUM; i++){ioctl(fd[i], LED_ON);sleep(1);ioctl(fd[i], LED_OFF);}}for(i = 0; i < LED_NUM; i++){close(fd[i]);}return 0;
}

[leiyuxing@centos6 LED_test]$/opt/buildroot-2012.08/arm920t/usr/bin/arm-linux-gcc led_test.c[leiyuxing@centos6 LED_test]$ lsa.out  led_test.c

应用程序使用交叉编译器编译得到a.out。

在我们的开发板上将  .ko文件和 a.out 文件 tftp 过去。这是板子上会有我们这两个文件，注意这两个文件的权限需要改成可执行。

insmod 文件名.ko  就可以看到我们的主设备号。  如major=251  

在开发板上执行的操作:

>: tftp -gr s3c_led.ko 192.168.1.2s3c_led.ko           100% |*******************************|  6210   0:00:00 ETA>: tftp -gr a.out 192.168.1.2a.out                100% |*******************************|  6007   0:00:00 ETA>: insmod s3c_led.koS3C led driver[major=251] version 1.0.0 installed successfully!>: mknod /dev/led0 c 251 0   //手动创建结点>: mknod /dev/led1 c 251 1>: mknod /dev/led2 c 251 2>: mknod /dev/led3 c 251 3>: ls -l dev/led* //查看我们的设备crw-r--r--    1 root     root      251,   0 Dec 31 17:20 dev/led0crw-r--r--    1 root     root      251,   1 Dec 31 17:20 dev/led1crw-r--r--    1 root     root      251,   2 Dec 31 17:21 dev/led2crw-r--r--    1 root     root      251,   3 Dec 31 17:21 dev/led3>: ll a.out-rw-r--r--    1 root     root          6007 Dec 31 17:17 a.out>: chmod 777 a.out>: ./a.out

最后 ./a.out   LED灯就能在开发板上跑起来，这就可以称为跑马灯了

出现问题：

问题一：

没有权限

解决方法：

>: ll a.out-rw-r--r--    1 root     root          6007 Dec 31 17:17 a.out>: chmod 777 a.out