嵌入式学习Day50

mycdev.c

#include 
#include 
#include 
#include 
/* myleds{
         led1= <&gpioe 10 0>;
         led2= <&gpiof 10 0>;
         led3= <&gpioe 8 0>;
    };
*/
char kbuf[128];
struct device_node *dnode;
int gpiono1, gpiono2, gpiono3;

int mycdev_open(struct inode *inode, struct file *file)
{
    return 0;
}
ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *lof)
{
    return 0;
}
ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size, loff_t *lof)
{
    unsigned long ret;
    // 从用户空间读取数据
    if (size > sizeof(kbuf))
        size = sizeof(kbuf);
    ret = copy_from_user(kbuf, ubuf, size);
    if (ret)
    {
        printk("从用户拷贝失败\n");
        return ret;
    }
    switch (kbuf[0])
    {
    case '1':
        gpio_set_value(gpiono1, 1);
        break;
    case '2':
        gpio_set_value(gpiono1, 0);
        break;
    case '3':
        gpio_set_value(gpiono2, 1);
        break;
    case '4':
        gpio_set_value(gpiono2, 0);
        break;
    case '5':
        gpio_set_value(gpiono3, 1);
        break;
    case '6':
        gpio_set_value(gpiono3, 0);
        break;
    }
    return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{
    return 0;
}
struct file_operations fops = {
    .open = mycdev_open,
    .read = mycdev_read,
    .write = mycdev_write,
    .release = mycdev_close,
};
int major;

static int __init mycdev_init(void)
{
    // 注册字符设备驱动
    major = register_chrdev(0, "mycdev", &fops);
    if (major < 0)
    {
        printk("字符设备驱动注册失败\n");
        return major;
    }
    printk("字符设备驱动注册成功%d\n", major);

    // 通过名字解析设备树驱动注册
    dnode = of_find_node_by_name(NULL, "myleds");
    if (dnode == NULL)
    {
        printk("设备树节点解析失败\n");
        return -ENOMEM;
    }
    printk("获取设备树节点成功\n");
    // 根据解析到的设备树节点信息结构体解析出GPIO编号
    gpiono1 = of_get_named_gpio(dnode, "led1", 0);
    if (gpiono1 < 0)
    {
        printk("获取GPIO编号失败\n");
        return 0;
    }
    printk("获取GPIO编号成功%d\n", gpiono1);
    gpiono2 = of_get_named_gpio(dnode, "led2", 0);
    if (gpiono1 < 0)
    {
        printk("获取GPIO编号失败\n");
        return 0;
    }
    printk("获取GPIO编号成功%d\n", gpiono2);

    gpiono3 = of_get_named_gpio(dnode, "led3", 0);
    if (gpiono1 < 0)
    {
        printk("获取GPIO编号失败\n");
        return 0;
    }
    printk("获取GPIO编号成功%d\n", gpiono3);

    // 申请GPIO编号
    gpio_request(gpiono1, NULL);
    gpio_request(gpiono2, NULL);
    gpio_request(gpiono3, NULL);

    // 设置GPIO方向为输出并默认输出低电平
    gpio_direction_output(gpiono1, 0);
    gpio_direction_output(gpiono2, 0);
    gpio_direction_output(gpiono3, 0);

    // 默认关灯
    gpio_set_value(gpiono1, 0);
    gpio_set_value(gpiono2, 0);
    gpio_set_value(gpiono3, 0);

    return 0;
}
static void __exit mycdev_exit(void)
{
    // 灭灯
    gpio_set_value(gpiono1, 0);
    gpio_set_value(gpiono2, 0);
    gpio_set_value(gpiono3, 0);
    // 释放GPIO编号
    gpio_free(gpiono1);
    gpio_free(gpiono2);
    gpio_free(gpiono3);

    // 注销字符设备驱动
    unregister_chrdev(major, "mycdev");
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

test.c

#include 
#include
#include 
#include 
#include 
#include 
 
int main(int argc,const char * argv[])
{
    char buf[128]={0};
    int fd=open("/dev/mycdev",O_RDWR);    
    if(fd<0){
        printf("打开设备文件失败\n");
    }
    while(1){
        //从终端读取
        printf("请输入操作那个灯\n");
        printf("1(LED1亮) 2(LED1灭) \n3(LED2亮) 4(LED2灭) \n5(LED3亮) 6(LED3灭)\n");
        printf("请输入>>");
        fgets(buf,sizeof(buf),stdin);
        buf[strlen(buf)-1]='\0';
        //向设备文件中写
        write(fd,buf,sizeof(buf));
    }
    close(fd);
    return 0;
}