fist char driver and app

fist char driver and app

 

driver:

  #include      //dev_t
#include       //struct cdev
#include         //alloc_chrdev_region()
#include     //class_create()
#include //copy_to_user

dev_t                  devid;
static struct cdev     *maytures_cdev;
static int             maytures_Major = 0;
static int             maytures_Minor = 0;
static struct class    *maytures_class;
int dev_ch;

static int maytures_open(struct inode *inode, struct file *file)
{
 /*open*/
 printk(KERN_ALERT "open_maytures.\n");

 return 0;
}

static ssize_t maytures_read(struct file *file, char __user *buf,
    size_t count, loff_t * ppos)
{
 printk(KERN_ALERT "read_maytures.\n");
 if(copy_to_user(buf, &dev_ch, sizeof(int))){
  printk(KERN_ALERT "sent_maytures.=dev=%d,%d\n",dev_ch,*buf); 
  return -EFAULT;
 }
}

static ssize_t maytures_write(struct file *file, const char __user *buf,
     size_t count, loff_t * ppos)
{
 printk(KERN_ALERT "write_maytures.\n");
 if(copy_from_user(&dev_ch, buf, sizeof(int))){
  printk(KERN_ALERT "get_maytures.=dev=%d,%d\n",dev_ch,*buf); 
  return -EFAULT;
 }
}

static struct file_operations maytures_fops = {
 .owner = THIS_MODULE,
 .open = maytures_open,
 .read = maytures_read,
 .write = maytures_write
};

static int __init maytures_init(void)
{
    int err;
 dev_ch = 168;
    //初始化cdev
    maytures_cdev        = cdev_alloc();
    cdev_init(maytures_cdev, &maytures_fops);
    maytures_cdev->owner = THIS_MODULE;

    //动态获取主设备号(dev_t devid中包含"主设备号"和"次设备号"信息)
    alloc_chrdev_region(&devid, 66, 1, "maytures");
    maytures_Major = MAJOR(devid);
    maytures_Minor = MINOR(devid);
    printk(KERN_ALERT "I was assigned major number %d.\n", maytures_Major);
    printk(KERN_ALERT "I was assigned minor number %d.\n", maytures_Minor);

    //注册字符设备 (1)
    err = cdev_add(maytures_cdev, devid, 1);
    if (err) {
        printk(KERN_NOTICE "Error %d adding device\n", err);
        return -1;
    }
// WM8350_SW_RESET_CHIP_ID_MASK = 0x0;
    maytures_class = class_create(THIS_MODULE, "maytures_class1");
    if (IS_ERR(maytures_class)) {
        printk(KERN_ALERT "create class error\n");
        return -1;
    }
    device_create(maytures_class, NULL, devid, NULL, "maytures" "%d", MINOR(devid));   

    return 0;
}

static void __exit maytures_exit(void)
{
    unregister_chrdev_region(devid, 1);
    cdev_del(maytures_cdev);

    device_destroy(maytures_class, devid);
    class_destroy(maytures_class);
 printk(KERN_ALERT "exit module.\n");
}

module_init(maytures_init);
module_exit(maytures_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("maytures ");
MODULE_DESCRIPTION("A sample driver");
MODULE_SUPPORTED_DEVICE("testdevice");

driver make file :

 

PWD := $(shell pwd)
KERNELDIR := /home/cmz/MyProjects/omap3/code/ema_psp-02.01.03.11
all: default
obj-m += maytures_chrdev.o
#ARCH=arm
#CROSS_COMPILE=arm-none-linux-gnueabi-

default:
        $(MAKE) -C $(KERNELDIR) M=$(PWD) modules
clean:
        rm *.mod.c *.o *.ko

app:  

//#include
//#include
#include
#include "stdio.h"
main()
{
 int fd,num;
 //打开
 
 printf("hello,open!\n");
 fd = open("/dev/maytures66",O_RDWR);
 if(fd != -1){
  printf("opened sucesses!\n");
  read(fd,&num,sizeof(int));
  printf("from kernel --%d!\n",num);
  /*输入数据送kernel*/
  scanf("%d",&num);
  printf("to kernel --%d!\n",num);
  write(fd,&num,sizeof(int));
   /*read kernel data*/
  read(fd,&num,sizeof(int));
  printf("from kernel --%d!\n",num);
  close(fd);
 }else{
  printf("open,failed!\n");
 }
 
}

app makefile:

 

ARCH=arm-v7
CROSS_COMPILE=arm-none-linux-gnueabi-

EXE=read

all:$(EXE)

$(EXE):read.c
        $(CROSS_COMPILE)gcc -o $@ read.c
clean:
        rm -rf read