Linux 驱动——Led驱动1

时间:2023-03-09 15:49:05
Linux 驱动——Led驱动1

led_drv.c驱动文件:

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <asm/io.h>          //包含 iomap 和 iounmap 函数         
#include <asm/uaccess.h>        //包含 copy_from_user 函数
#include <linux/device.h>        //包含 class 类相关的处理函数
#include <linux/fs.h>              //包含 file_operations 结构体

#define DRIVER_NAME "led_drv"
#define DEVICE_NAME "led_dev"

int major;

static struct class *leddrv_class;
static struct class_device *leddrv_class_dev;

volatile unsigned long *gpfcon = NULL;
volatile unsigned long *gpfdat = NULL;

static int led_drv_open(struct inode *inode, struct file *file)
{
  *gpfcon &= ~((0x3<<(4*2)) | (0x3<<(5*2)) | (0x3<<(6*2)));
  *gpfcon |= ((0x1<<(4*2)) | (0x1<<(5*2)) | (0x1<<(6*2)));
  return 0;
}

static ssize_t led_drv_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
  int val, ret;

  ret = copy_from_user(&val, buf, count);
  if(ret!=0)
  {
    printk("led_drv_write error 1 \n");
  }

  if (val == 1)
  {
    *gpfdat &= ~((1<<4) | (1<<5) | (1<<6));    //点灯
  }
  else
  {
    *gpfdat |= (1<<4) | (1<<5) | (1<<6);      //灭灯
  }
  return 0;
}

static struct file_operations led_drv_fops = {
  .owner = THIS_MODULE,
  .open = led_drv_open,
  .write = led_drv_write,
};

static int led_drv_init(void)
{
  major = register_chrdev(0, DRIVER_NAME, &led_drv_fops);

  leddrv_class = class_create(THIS_MODULE, DRIVER_NAME);                                          //创建设备类

  leddrv_class_dev = class_device_create(leddrv_class, NULL, MKDEV(major, 0), NULL, DEVICE_NAME); //在设备类下创建设备文件其实也就是设备节点,

                                                                                                                       //创建好的设备文件(设备节点)可以在中/dev

                                                                                                                       //下查看, 如果创建成功,则在/dev下应该有 

                                                                                                   //led_dev这个设备文件名,或者说是有 

                                                                                                   //led_dev这个设备节点

  gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
  gpfdat = gpfcon + 1;

  return 0;
}

static void led_drv_exit(void)
{
  unregister_chrdev(major, DRIVER_NAME);

  class_device_unregister(leddrv_class_dev);
  class_destroy(leddrv_class);
  iounmap(gpfcon);
}

module_init(led_drv_init);

module_exit(led_drv_exit);

MODULE_LICENSE("GPL");

Makefile文件:

obj-m += led_drv.o

KERN_DIR = /work/system/linux-2.6.22.6

all:

  make -C $(KERN_DIR) M=`pwd` modules

clean:

  rm -rf *.o *.ko *.order *.symvers *.mod.c

led_app文件:

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>

int main(int argc, char **argv)
{
  int fd;
  int val = 1;
  fd = open("/dev/led_dev", O_RDWR);
  if(fd<0)
  {
    printf("can not open \n");
  }

  if(argc != 2)
  {
    printf("%s <on|off> \n");
    return 0;
  }
  if(strcmp(argv[1], "on") == 0)
  {
    val = 1;
  }
  else
  {
    val = 0;
  }
  write(fd, &val, 4);

  return 0;
}

编译led_drv.c与led_app.c文件, 加载编译后的模块, 运行./led_app on 或 ./led_app off可以看到灯的亮灭。