10.20嵌入式作业（platform总线）

作业内容

通过platform总线驱动实现
a.应用程序通过阻塞的io模型来读取number变量的值
b.number是内核驱动中的一个变量
c.number的值随着按键按下而改变（按键中断） 例如number=0 按下按键number=1 ,再次按下按键number=0
d.在按下按键的时候需要同时将led1的状态取反
e.驱动中需要编写字符设备驱动
f.驱动中需要自动创建设备节点
g.这个驱动需要的所有设备信息放在设备树的同一个节点中

代码部分

mypdrv.c

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

#define CNAME "mycdev"
struct property *pr;    //属性结构体指针
int minor = 0;          //次设备号从0开始
unsigned int major = 0; //动态申请

char kbuf[128] = {}; //定义数组用于存放和用户之间拷贝的数据
struct cdev *cdev;
struct class *cls;
struct device *dev;
struct device_node *node;
unsigned int irqno; //接收软中断号
unsigned int count = 0;
//定义队列头
wait_queue_head_t wq_head;
unsigned int condition = 0; //判断是否有数据准备好的标识变量
unsigned int number = 0;
struct gpio_desc *desc;
struct resource *res;
irqreturn_t irq_handler(int irq, void *dev)
{
    gpiod_set_value(desc, !gpiod_get_value(desc));
    number ^= 1;
    //唤醒
    condition = 1;
    wake_up_interruptible(&wq_head);
    return IRQ_HANDLED;
}

//对应的是open()
int mycdev_open(struct inode *inode, struct file *file)
{

    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}
// read()
ssize_t mycdev_read(struct file *file, char __user *ubuf, size_t size, loff_t *loff)
{
    int ret;
    //阻塞
    ret = wait_event_interruptible(wq_head, condition);
    if (ret)
    {
        printk("接收阻塞休眠\n");
        return ret;
    }

    if (size > sizeof(number))
        size = sizeof(number);
    ret = copy_to_user(ubuf, &number, size);
    if (ret)
    {
        printk("数据从内核向用户拷贝失败\n");
        return -EIO;
    }
    condition = 0;
    return size;
}

// close()
int mycdev_close(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}
//操作方法结构体的初始化
struct file_operations fops =
    {
        .open = mycdev_open,
        .read = mycdev_read,
        .release = mycdev_close,
};

int pdrv_probe(struct platform_device *pdr)
{
    int ret;
    //获取设备信息
    printk("%s:%d\n", __FILE__, __LINE__);
    res = platform_get_resource(pdr, IORESOURCE_MEM, 0);
    if (res == NULL)
    {
        printk("获取资源失败\n");
        return -ENODATA;
    }
    //获取GPIO编号
    desc = gpiod_get_from_of_node(pdr->dev.of_node, "led2", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(desc))
    {
        printk("获取GPIO编号失败\n");
        return PTR_ERR(desc);
    }
    irqno = platform_get_irq(pdr, 0);
    if (irqno < 0)
    {
        printk("获取资源失败\n");
        return irqno;
    }
    //注册中断
    ret = request_irq(irqno, irq_handler, IRQF_TRIGGER_FALLING, "key1_inte", NULL);
    if (ret)
    {
        printk("register zhongduan failed\n");
        return ret;
    }
    printk("register zhongduan success\n");
    printk("%#x    %d\n", res->start, irqno);

    return 0;
}
int pdrv_remove(struct platform_device *pdr)
{
    printk("%s:%d\n", __FILE__, __LINE__);
    return 0;
}
//定义compatible表
struct of_device_id oftable[] = {
    {.compatible = "hqyj,platform"},
    {},
};
MODULE_DEVICE_TABLE(of, oftable);
//定义并初始化对象
struct platform_driver pdrv = {
    .probe = pdrv_probe,
    .remove = pdrv_remove,
    .driver = {
        .name = "test",
        .of_match_table = oftable, //设备树匹配
    },
};

static int __init mycdev_init(void)
{
    int ret;
    //动态注册字符设备驱动
    major = register_chrdev(0, CNAME, &fops);
    if (major < 0)
    {
        printk("char dev driver register failed\n");
        return major;
    }
    printk("char dev driver register success! major=%d\n", major);

    //自动创建设备节点
    cls = class_create(THIS_MODULE, "led");
    if (IS_ERR(cls))
    {
        printk("dir failed\n");
        ret = PTR_ERR(cls);
        goto ERR4;
    }
    printk("mkdir success\n");
    //向上提交节点信息

    dev = device_create(cls, NULL, MKDEV(major, minor), NULL, "my_led0");
    if (IS_ERR(dev))
    {
        printk("jiedain failed\n");
        ret = PTR_ERR(dev);
        goto ERR5;
    }
    printk("jiedain my_led0 success\n");

    //注册对象
    platform_driver_register(&pdrv);
    init_waitqueue_head(&wq_head);
    return 0;

ERR5:
    // device_destroy(cls,MKDEV(major,0));
    class_destroy(cls);
ERR4:
    unregister_chrdev(major, CNAME);
    return ret;
}
static void __exit mycdev_exit(void)
{
    // 1.销毁设备节点
    device_destroy(cls, MKDEV(major, 0));
    class_destroy(cls);
    //注销字符设备驱动
    unregister_chrdev(major, CNAME);
    //释放GPIO编号
    gpiod_direction_output(desc, 0);
    gpiod_put(desc);
    //注销中断
    free_irq(irqno, NULL);
    //注销
    platform_driver_unregister(&pdrv);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

test.c

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

int main(int argc, char const *argv[])
{
    char buf[128] = {};
    int num;
    int fd;
    fd = open("/dev/my_led0", O_RDWR);
    if (fd < 0)
    {
        printf("open my_led0 failed\n");
        printf("%d\n", errno);
        exit(-1);
    }
    printf("open my_led0 success\n");

    while (1)
    {
        // memset(buf,0,sizeof(buf));
        read(fd, &num, sizeof(num));

        printf("number = %d\n", num);
    }
    close(fd);
    return 0;
}

测试结果