linux驱动开发FL2440开发板-LED驱动及其测试程序

———————————————————————————————————————

主机操作系统：Centos 6.7
交叉编译器环境：arm-linux-gcc-4.5.4 
开发板平台： FL2440 
Linux内核版本： linux-3.0 
开发模块： LED
邮箱：[email protected]
———————————————————————————————————————

1.1vim编写LED驱动代码

[leiyuxing@centos6 ~]$ mkdir LED

[leiyuxing@centos6 LED]$ vim s3c_led

/*********************************************************************************
 *      Copyright:  (C) 2016  leiyuxing <[email protected]>
 *                  All rights reserved.
 *
 *       Filename:  s3c_led.c
 *    Description:  This file
 *
 *        Version:  1.0.0(07/25/2016~)
 *         Author:  leiyuxing <[email protected]>
 *      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  <[email protected]>"
#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_fops
 
    result = 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.o
 
default:
        $(MAKE) -C $(KDIR) M=`pwd` modules
        make clean
 
clean:
        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]$ ls

Makefile  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 <[email protected]>
 *                  All rights reserved.
 *
 *       Filename:  led_test.c
 *    Description:  This file
 *                 
 *        Version:  1.0.0(07/25/2016)
 *         Author:  leiyuxing  <[email protected]>
 *      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]$ ls

a.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 192.168.1.2

s3c_led.ko           100% |*******************************|  6210   0:00:00 ETA

>: tftp -gr a.out 192.168.1.2

a.out                100% |*******************************|  6007   0:00:00 ETA

>: insmod s3c_led.ko

S3C 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/led0

crw-r--r--    1 root     root      251,   1 Dec 31 17:20 dev/led1

crw-r--r--    1 root     root      251,   2 Dec 31 17:21 dev/led2

crw-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