GPIO子系统

在内核模块中启用定时器，让LED1亮1s灭1s

实验效果

驱动程序

#include 
#include 
#include
#include
#include
#include 
/*
   myleds{
       led1=<&gpioe 10 0>;    
       led2=<&gpiof 10 0>; 
       led3=<&gpioe 8 0>;  
    };
*/
struct device_node *dnode;
struct gpio_desc *gpiono;
//分配定时器对象
struct timer_list mytimer;
//定时器处理函数
void mytimer_func(struct timer_list *timer)
{
    //LED1亮1秒灭1秒
    gpiod_set_value(gpiono,!gpiod_get_value(gpiono));
    //再次启用定时器
    mod_timer(timer,jiffies+HZ);
}
static int __init mycdev_init(void)
{
    //初始化定时器对象
    mytimer.expires=jiffies+HZ;//设置定时1S的阈值
    timer_setup(&mytimer,mytimer_func,0);
    //将定时器注册进内核
    add_timer(&mytimer);
    
    //解析led灯的设备树节点
    dnode=of_find_node_by_path("/myleds");
    if(dnode==NULL)
    {
    printk("解析设备树节点失败\n");
    return -ENXIO;
    }
    printk("解析设备树节点成功\n");
      //根据设备树节点解析led1gpio编号
    gpiono=gpiod_get_from_of_node(dnode,"led1",0,GPIOD_OUT_LOW,NULL);
    if(IS_ERR(gpiono))
    {
        printk("gpio编号解析失败\n");
        return -PTR_ERR(gpiono);
    }
    printk("解析gpio编号成功\n");
 
    return 0;
}
static void __exit mycdev_exit(void)
{
    //灭灯
    gpiod_set_value(gpiono,0);
    //释放gpio编号
    gpiod_put(gpiono);
    del_timer(&mytimer);
 
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

基于GPIO子系统完成LED驱动的注册，应用程序测试

实验效果

驱动程序

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define LED_ON _IOW('l',1,int)  //开灯
#define LED_OFF _IOW('l',0,int)//关灯

struct cdev *cdev;
unsigned int major = 500;
unsigned int minor = 0;
dev_t devno;
struct class *cls;
struct device *dev;
char kbuf[128] = {0};
struct device_node *dnode;
struct gpio_desc *gpiono1;
struct gpio_desc *gpiono2;
struct gpio_desc *gpiono3;

//封装操作方法
int mycdev_open(struct inode *inode, struct file *file)
{
    unsigned int aaa=MINOR(inode->i_rdev);//得到打开的文件对应的设备号
    file->private_data=(void *)aaa;
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    int which,ret;
    ret = copy_from_user(&which,(void *)arg,4);
    if(ret)
    {
        printk("Copy to user failed\n");
        return -EIO;
    }
    printk("Copy to user successful\n");

    switch(cmd)
    {
        case LED_ON:
        switch (which)
        {
        case 1:     //亮灯
            gpiod_set_value(gpiono1,1);
            break;
        case 2:     //亮灯
            gpiod_set_value(gpiono2,1);
            break;
        case 3:     //亮灯
            gpiod_set_value(gpiono3,1);
            break;
        default:
            break;
        }
        break;
        case LED_OFF:
        switch(which)
        {
            case 1:
                gpiod_set_value(gpiono1,0);
                break;
            case 2:
                gpiod_set_value(gpiono2,0);
                break;
            case 3:
                gpiod_set_value(gpiono3,0);
                break;
        }
        break;
    }
    return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}
// 定义操作方法结构体变量并完成初始化
struct file_operations fops =
    {
        .open = mycdev_open,
        .unlocked_ioctl = mycdev_ioctl,
        .release = mycdev_close,
};

static int __init mycdev_init(void)
{
    int ret, i;
    // 1.分配字符设备驱动对象空间  cdev_alloc
    cdev = cdev_alloc();
    if (cdev == NULL)
    {
        printk("申请字符设备驱动对象空间失败\n");
        ret = -EFAULT;
        goto out1;
    }
    printk("字符设备驱动对象申请成功\n");
    // 2.字符设备驱动对象部分初始化  cdev_init
    cdev_init(cdev, &fops);
    // 3.申请设备号  register_chrdev_region/alloc_chrdev_region
    if (major > 0) // 静态申请设备号
    {
        ret = register_chrdev_region(MKDEV(major, minor), 3, "myled");
        if (ret)
        {
            printk("静态指定设备号失败\n");
            goto out2;
        }
    }
    else // 动态申请设备号
    {
        ret = alloc_chrdev_region(&devno, minor, 3, "myled");
        if (ret)
        {
            printk("动态申请设备号失败\n");
            goto out2;
        }
        major = MAJOR(devno); // 根据设备号得到主设备号
        minor = MINOR(devno); // 根据设备号得到次设备号
    }
    printk("申请设备号成功\n");
    // 4.注册字符设备驱动对象  cdev_add()
    ret = cdev_add(cdev, MKDEV(major, minor), 3);
    if (ret)
    {
        printk("注册字符设备驱动对象失败\n");
        goto out3;
    }
    printk("注册字符设备驱动对象成功\n");
    // 5.向上提交目录
    cls = class_create(THIS_MODULE, "myled");
    if (IS_ERR(cls))
    {
        printk("向上提交目录失败\n");
        ret = -PTR_ERR(cls);
        goto out4;
    }
    printk("向上提交目录成功\n");
    // 6.向上提交设备节点
    for (i = 0; i < 3; i++)
    {
        dev = device_create(cls, NULL, MKDEV(major, i), NULL, "myled%d", i);
        if (IS_ERR(dev))
        {
            printk("向上提交节点信息失败\n");
            ret = -PTR_ERR(dev);
            goto out5;
        }
    }
    printk("向上提交设备节点信息成功\n");
    // 解析led灯的设备树节点
    dnode = of_find_node_by_name(NULL, "myleds");
    if (dnode == NULL)
    {
        printk("解析设备树节点失败\n");
    }
    printk("解析设备树节点成功\n");
    // 根据设备树节点解析led1gpio编号
    gpiono1 = gpiod_get_from_of_node(dnode,"led1",0,GPIOD_OUT_LOW,NULL);
    if(IS_ERR(gpiono1))
    {
        printk("gpio编号解析失败\n");
        return -PTR_ERR(gpiono1);
    }
    printk("解析gpio1编号成功gpiono1\n");
    // 根据设备树节点解析led2gpio编号
    gpiono2 = gpiod_get_from_of_node(dnode,"led2",0,GPIOD_OUT_LOW,NULL);
    if(IS_ERR(gpiono2))
    {
        printk("gpio编号解析失败\n");
        return -PTR_ERR(gpiono2);
    }
    printk("解析gpio2编号成功gpiono2\n");
    // 根据设备树节点解析led3gpio编号
    gpiono3 = gpiod_get_from_of_node(dnode,"led3",0,GPIOD_OUT_LOW,NULL);
    if(IS_ERR(gpiono3))
    {
        printk("gpio编号解析失败\n");
        return -PTR_ERR(gpiono3);
    }
    printk("解析gpio3编号成功gpiono3\n");
    // 亮灯
    gpiod_set_value(gpiono1, 1);
    // 亮灯
    gpiod_set_value(gpiono2, 1);
    // 亮灯
    gpiod_set_value(gpiono3, 1);
    return 0;

out5:
    for (--i; i >= 0; i--)
    {
        // 销毁上面提交的设备信息
        device_destroy(cls, MKDEV(major, i));
    }
    class_destroy(cls);
out4:
    cdev_del(cdev);
out3:
    unregister_chrdev_region(MKDEV(major, minor), 3);
out2:
    kfree(cdev);
out1:
    return ret;
}
static void __exit mycdev_exit(void)
{
    // 1.销毁设备信息  device_destroy
    int i;
    for (i = 0; i < 3; i++)
    {
        device_destroy(cls, MKDEV(major, i));
    }
    // 2.销毁目录  class_destroy
    class_destroy(cls);
    // 3.注销对象  cdev_del()
    cdev_del(cdev);
    // 4.释放设备号   unregister_chrdev_region()
    unregister_chrdev_region(MKDEV(major, minor), 3);
    // 5.释放对象空间  kfree()
    kfree(cdev);
    // 6.释放gpio编号
    gpiod_put(gpiono1);
    gpiod_put(gpiono2);
    gpiod_put(gpiono3);

}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

test.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define LED_ON _IOW('l', 1, int)
#define LED_OFF _IOW('l', 0, int)

void LED_control()
{
    int a, b;
    char buf[128] = {0};
    int fd_led = open("/dev/myled0", O_RDWR);
    if (fd_led < 0)
    {
        printf("打开设备文件失败\n");
        exit(-1);
    }
    while (1)
    {
        // 从终端读取
        printf("请选择灯功能\n");
        printf("0(关灯) 1(开灯)>");
        scanf("%d", &a);
        printf("请输入要控制的灯\n");
        printf("1(LED1) 2(LED2) 3(LED3)>");
        scanf("%d", &b);
        if (a == 1) // 开灯
        {
            ioctl(fd_led, LED_ON, &b);
        }
        else if (a == 0) // 关灯
        {
            ioctl(fd_led, LED_OFF, &b);
        }
    }
    close(fd_led);
}

int main(int argc, char const *argv[])
{
    LED_control();
    return 0;
}