ARM&Linux下驱动开发第二节

#include
#include
#include
#include /* COPY_TO_USER */
#include
#define DEV_NAME "rwtest"
static int major=0;
static int MAX_BUF_LEN=1024;
static char drv_buf[1024];
static int WRI_LENGTH=0;
/************************************写入*************************************************/
static ssize_t dx_write(struct file *file, const char __user *buffer, size_t count, loff_t * ppos)
{
if(count > MAX_BUF_LEN)count = MAX_BUF_LEN;
copy_from_user(drv_buf , buffer, count);
WRI_LENGTH = count;
printk("write data to driver\n");
return count;
}
/**************************************读取***********************************************/
static ssize_t dx_read(struct file *filp, char __user *buffer, size_t count, loff_t *ppos)
{
int i=0,j=0;
if(count > MAX_BUF_LEN)
count=MAX_BUF_LEN;
for(i=strlen(drv_buf);i>0;i--)
{
buffer[j]=drv_buf[i-1];
j++;
}
//copy_to_user(buffer,drv_buf,count);
printk("read data from driver\n");
return count;
}
//===========================打开=========================================
static int dx_open(struct inode *inode, struct file *filp)
{
printk("device open sucess!\n");
return 0;
}
/**********************************release***************************************************/
static int dx_release(struct inode *inode, struct file *filp)
{
printk("device release\n");
return 0;
}
//======================结构体,驱动各属性==================================================
static struct file_operations file_opt = {
owner: THIS_MODULE,
write: dx_write,
read: dx_read,
open: dx_open,
release:dx_release,
};
//----------------------------------------------------------------------
static int __init qudong_init(void)
{
int ret;
ret = register_chrdev(0, DEV_NAME, &file_opt);
if(ret<0)
{
printk(DEV_NAME " can‘t get major number\n");
return 0;
}
major=ret;
printk("dx module major number is %d\n", ret);
return 0;
}
//-----------------------------------------------------------------------
static void __exit qudong_exit(void)
{
unregister_chrdev(major,DEV_NAME);
printk("exit\n");
}
module_init(qudong_init);
module_exit(qudong_exit);
MODULE_LICENSE("GPL");

## Makefile template.
obj-m := qudong.o
UNAME := $(shell uname -r)
PWD := $(shell pwd)
ADVMOD := qudong
defualt:
@make -C /lib/modules/$(UNAME)/build SUBDIRS=$(PWD) modules
clean:
@rm -f *.o
@rm -f *.ko
@rm -f *.mod.c
@rm -f .*.cmd
@rm -rf .tmp_versions
#endif

ifneq ($(KERNELRELEASE),)
obj-m := hello.o
else
KDIR := /usr/src/linux2.6.28
all:
make -C $(KDIR) M=$(PWD) modules ARCH=arm CROSS_COMPILE=arm-linux-
clean:
rm -f *.ko *.o *.mod.o *.mod.c *.symvers modul*
endif

#include
#include
#include
#include
#include
#include<string.h>
int main()
{
int fd=0;
int ret=0;
char bufw[100]={‘\0‘};
char bufr[100]={‘\0‘};
fd=open("/dev/rwtest",O_RDWR);
if(fd<0)
{
perror("open error\n");
return 0;
}
printf("Please input string:\n");
scanf("%s",bufw);
ret=write(fd,bufw,strlen(bufw));
if(ret<0)
{
perror("write error\n");
return 0;
}
printf("burw====%s\n",bufw);
ret=read(fd,bufr,99);
if(ret<0)
{
perror("read error\n");
return 0;
}
printf("bufr====%s\n",bufr);
close(fd);
return 0;
}