pcDuino day3

Hello_module.c

#include <linux/init.h>#include <linux/module.h>#include <linux/fs.h>#include <asm/uaccess.h>#include <linux/slab.h>MODULE_AUTHOR("song");MODULE_LICENSE("GPL");MODULE_DESCRIPTION("A simple test for kernel module.");MODULE_ALIAS("a simple module");int hello_open(struct inode *, struct file *);int hello_release(struct inode *, struct file *);ssize_t hello_read(struct file *, char __user *buff, size_t bufsiz, loff_t *);ssize_t hello_write(struct file *, const char __user *buff, size_t bufsiz, loff_t *);struct file_operations hello_fops = {    .open = hello_open,    .release = hello_release,    .read = hello_read,    .write = hello_write,};#define DEVICE_NAME "Hello_Driver" //proc/devices#define BUFF_SIZE 128int major;unsigned char *pbuff;int rd_pos;int wr_pos;static int __init hello_init(void){    printk(DEVICE_NAME" Hello world in kernel module\n");    major = register_chrdev(0, DEVICE_NAME, &hello_fops);   //12位主设备号 20位次设备号    if(major < 0){        printk(DEVICE_NAME" register %s fial\n", DEVICE_NAME);        return major;    }    printk(DEVICE_NAME" got major number: %d\n", major);    return 0;}static void __exit hello_exit(void){    printk(DEVICE_NAME" Hello world exit\n");    unregister_chrdev(major, DEVICE_NAME); //释放资源}module_init(hello_init); //模块加载module_exit(hello_exit); //模块卸载int hello_open(struct inode *pinode, struct file *pfile){    printk(DEVICE_NAME" hello_open\n");    wr_pos = 0;    rd_pos = 0;    pbuff = (unsigned char *)kmalloc(BUFF_SIZE, 0);    if(pbuff == NULL)    {        printk(DEVICE_NAME" kmalloc fail\n");        return 1;    }    return 0;}int hello_release(struct inode *pinode, struct file *pfile){    printk(DEVICE_NAME" hello_release\n");    kfree(pbuff);    return 0;}// __user *buff 用户空间内存地址ssize_t hello_read(struct file *pfile, char __user *buff, size_t bufsiz, loff_t *poffset){    int i = 0;    for(i = 0; i < bufsiz && (wr_pos - rd_pos) > 0; i++)    {        put_user(pbuff[rd_pos%BUFF_SIZE], buff + i);    //复制一个字节从内核空间到用户空间        rd_pos++;    }#if 0    int len = wr_pos - rd_pos;    if(len > 0){        int err = copy_to_user((char *)buff, pbuff + rd_pos%BUFF_SIZE, len > bufsiz ? bufsiz : len);        rd_pos += len > bufsiz ? bufsiz : len;        if(!err)            return len > bufsiz ? bufsiz : len;    }#endif    return i;}ssize_t hello_write(struct file *pfile, const char __user *buff, size_t bufsiz, loff_t *poffset){    int i = 0;    for(i = 0; i < bufsiz && (BUFF_SIZE - (wr_pos - rd_pos)) > 0; i++)    {        get_user(pbuff[wr_pos%BUFF_SIZE], buff + i);    //复制一个字节从内核空间到用户空间        wr_pos++;    }    return i;#if 0    int free_len = BUFF_SIZE - (wr_pos - rd_pos);    if(free_len > bufsiz)    {        int err = copy_from_user((char *)pbuff+wr_pos%BUFF_SIZE, buff, bufsiz);        wr_pos += bufsiz;        if(!err)            return bufsiz;    }    return -1;#endif}

Makefile

obj-m := hello_module.oKDIR := /home/mrhjlong/workspace/pcDuino/a20-kernel/build/sun7i_defconfig-linuxall:    make -C $(KDIR) M=$(PWD) modules ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-clean:    rm -f *.ko *.o *.mod.o *.mod.c *.symvers modul*

模块处理

板子系统：
装载：insmod hello_module.ko
卸载：rmmod hello_module
查看：lsmod
查看module信息：modinfo
查看打印信息：
tail /var/log/syslog
cat /proc/modules | grep hello
cat /proc/devices | grep Hello

查看头文件（fs.h 结构体定义）：
/home/mrhjlong/workspace/pcDuino/a20-kernel/linux-sunxi/include/linux/fs.h

创建结点（/proc/device/）：mknod hello-drv c 241 0
ls -l hello-drv

test_hello_drv.c

#include <stdio.h>#include <stdlib.h>#include <fcntl.h>int main(void){        unsigned char buff[10] = {0};        int fd = open("/dev/hello-drv", O_RDWR);        if(fd < 0)        {                perror("open");                return 1;        }        while(1)        {                int wr = write(fd, "hello world", strlen("hello world"));                printf("write return %d \n", wr);                int rd = read(fd, buff, 64);                if(rd < 0)                        perror("read");                printf("read return %d, %s\n", rd, buff);                memset(buff, 0, 64);                sleep(1);        }        close(fd);        return 0;//      unsigned int buff[10];//      int fd = open("/dev/hello-drv", O_RDWR);//      if(fd < 0)//      {//              perror("open");//              return 1;//      }//      int rd = read(fd, buff, 10);//      printf("Read return %d \n", rd);//      int wd = write(fd, buff, 10);//      if(wd < 0)//              perror("write");//      printf("write return %d\n", wd);//      close(fd);//      return 0;}