驱动基础——字符设备3

#include <linux/module.h> #include <linux/slab.h> #include <linux/kernel.h> #include <linux/init.h> #include <linux/fs.h> #include <linux/device.h> #include <linux/cdev.h> #include <linux/major.h> #include <asm/uaccess.h> static ssize_t flash_env_dev_open(struct inode *inode,struct file *file) {     return 0; } static ssize_t flash_env_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) {     unsigned char *p = (unsigned char *)kmalloc(11,GFP_KERNEL);     memcpy(p,"lingjiujianke",13);     if(!(copy_to_user(buf,p,10)))     {         printk("<1>copy okn");     }     return 0; } static ssize_t flash_env_dev_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) {     unsigned char *p=kmalloc(11,GFP_KERNEL);     if(copy_from_user(p,buf,10)==0)     {         printk("<1>%sn",p);     }     kfree(p);     return 0; } static ssize_t flash_env_dev_ioctl(struct inode *inode,struct file *file,unsigned int cmd,unsigned long arg) {     printk("<1> %dn",cmd);     switch(cmd){     case 0:         printk("<1> in flash 0n");         break;     case 1:         printk("<1> in flash 1n");         break;     default:         printk("<1> othersn");     }     return 0; } static const struct file_operations flash_fops = {     .owner    =THIS_MODULE,     .open    = flash_env_dev_open,     .read    = flash_env_dev_read,     .write    = flash_env_dev_write,     .ioctl    = flash_env_dev_ioctl, }; #define MAX_FLASH_ENV_MINORS 262 static struct cdev flash_cdev; dev_t dev; static __init int flash_env_dev_init(void) {     int res;     dev=MKDEV(263,262); cdev_init(&flash_cdev,&flash_fops);     res=register_chrdev_region(dev, MAX_FLASH_ENV_MINORS, "/dev/read_dev");     if(res)         printk("<1> fuckn");              res=cdev_add(&flash_cdev,dev,MAX_FLASH_ENV_MINORS);     if(res)         printk("<1> fuck2 n"); /*    devfs_mk_dir("flash_env_dev");*/     printk("<1> Hello Worldn");     return 0; } static void __exit flash_env_dev_exit(void) {     unregister_chrdev_region(dev,MAX_FLASH_ENV_MINORS);     printk("<1> exit Hello Worldn"); } module_init(flash_env_dev_init); module_exit(flash_env_dev_exit);

KERNELDIR = /usr/src/kernels/2.6.27.25-170.2.72.fc10.i686     PWD := $(shell pwd) obj-m := chrdev.o modules:     $(MAKE) -C $(KERNELDIR) M=$(PWD) modules     gcc test_chrdev.c -o test_chrdev clean:     rm -rf *.o *.ko test_chrdev Module.* module* *.mod.c

#include <stdio.h> #include <unistd.h> #include <fcntl.h> #include <sys/stat.h> #include <sys/types.h> #include <sys/ioctl.h> #include <stdlib.h> #include <string.h> int main() {     int fd=0;     int ret=0;     unsigned char buffer[20];     fd=open("/dev/read_dev", O_RDWR);     if(fd<0)         printf("open file errorn");     memset(buffer,0,20);     ret=read(fd,buffer,10);     if(ret<0)         printf("ioctl errorn");     if(buffer)     {         printf("the buffer is |%s|n",buffer);     }     return 0; }