字符设备驱动一

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/arch/regs-gpio.h>
#include <asm/hardware.h>


static int first_chrdev_open(struct inode *inode, struct file *file)
{
    printk("first_chrdev_open\n\r");
    return 0;
}


static ssize_t first_chrdev_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
    printk("first_chrdev_write\n\r");
    return 0;
}


static struct file_operations first_chrdev_fops = {
    .owner  =   THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */
    .open   =   first_chrdev_open,
    .write    =    first_chrdev_write,
};


int major;
static int first_chrdev_init(void)
{
    /* 0表示让系统自动为我们分配一个从1到255的主设备号*/
    major = register_chrdev(0, "first_chrdev", &first_chrdev_fops);  //注册
    return 0;
}

static void first_chrdev_exit(void)
{
    unregister_chrdev(major, "first_chrdev");                    //卸载

}

module_init(first_chrdev_init);
module_exit(first_chrdev_exit);

MODULE_LICENSE("GPL");

#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/xyz",O_RDWR);
    if(fd < 0)
    {
        printf("can‘t open!\n");
    }
    write(fd, &val, 4);

    return 0;
}

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/arch/regs-gpio.h>
#include <asm/hardware.h>

static struct class *led_chrdev_class;    //定义一个类
static struct class_device *led_chrdev_class_dev;    //定义一个设备

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

static int led_chrdev_open(struct inode *inode, struct file *file)
{
    printk("led_chrdev_open\n\r");
    *gpfcon &= ~((3<<(4*2)) | (3<<(5*2)) | (3<<(6*2)));
    *gpfcon |=  ((1<<(4*2)) | (1<<(5*2)) | (1<<(6*2)));
    return 0;
}


static ssize_t led_chrdev_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
    int val;
    printk("led_chrdev_write\n\r");
    copy_from_user(&val, buf, count); //从用户空间到内核空间，buf：应用程序传入的值
    if(val == 1)
    {
        //open led
        *gpfdat  &= ~((1<<4) | (1<<5) | (1<<6));
    }
    else
    {
        //close led
        *gpfdat |=  ((1<<4) | (1<<5) | (1<<6));
    }
    return 0;
}


static struct file_operations led_chrdev_fops = {
    .owner  =   THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */
    .open   =   led_chrdev_open,
    .write    =    led_chrdev_write,
};


int major;
static int led_chrdev_init(void)
{
    major = register_chrdev(0, "led_chrdev", &led_chrdev_fops);  //在内核的字符设备数组中注册一个file_operation结构
    led_chrdev_class = class_create(THIS_MODULE, "ledchrdev");        //创建一个类:会自动的在(/sys/class)目录下自动创建一个(ledchrdev)这个类。
    //自动创建一个设备：会自动的在(/sys/class/ledchrdev)这个目录里面创建一个(xyz)文件夹,这个文件夹内有一个(dev)文件，它的内容是(252:0)主设备号和此设备号。
    led_chrdev_class_dev = class_device_create(led_chrdev_class, NULL, MKDEV(major, 0), NULL, "xyz");
    gpfcon = (volatile unsigned int *)ioremap(0x56000050, 16);
    gpfdat = gpfcon + 1;
    return 0;
}

static void led_chrdev_exit(void)
{
    unregister_chrdev(major, "led_chrdev");                    //卸载：从内核的字符设备数组中一主设备号找到这一项把它卸载
    class_device_unregister(led_chrdev_class_dev);            //删除自动创建的设备
    class_destroy(led_chrdev_class);                        //摧毁自动创建的类
    iounmap(gpfcon);
}

module_init(led_chrdev_init);
module_exit(led_chrdev_exit);

MODULE_LICENSE("GPL");

#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/xyz",O_RDWR);
    if(fd < 0)
    {
        printf("can‘t open!\n");
    }
    if(argc != 2)
    {
        printf("Usage :\n\r");
        printf("%s <on/off>\n\r", argv[0]);
        return 0;
    }

    if(strcmp(argv[1], "on") ==0)
    {
        val = 1;
    }
    else
    {
        val = 0;
    }
    write(fd, &val, 4);
    return 0;
}