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

#include 
#include 
#include 
#include 
#include 
 
#include 
#include 
#include 
#include 
#include 
#include 
 
#include 
#include "myled.h"
#include 
#include 
#include 
#include 
#include 
 
struct resource *res;
int irqno;
struct gpio_desc *desc;
struct gpio_desc *desc1;
 
wait_queue_head_t head;
unsigned int condition;
unsigned char number;
 
struct cdev *cdev;
 
struct class* cls;
struct device* dev;
dev_t dev1;
unsigned int major;
unsigned int minor;
 
//操作方法结构体
ssize_t mycdev_read(struct file *file, char __user *ubuf, size_t size, loff_t *loff)
{
    int ret;
    if(file->f_flags&O_NONBLOCK)
    {
        return -EINVAL;
    }else
    {
        ret=wait_event_interruptible(head,condition);
        if(ret)
        {
            printk("接收阻塞，休眠\n");
            return ret;
        }
    }
    if(size>sizeof(char))
        size=sizeof(char);
    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;
}
ssize_t mycdev_write(struct file *file, const char __user *ubuf, size_t size, loff_t *loff)
{
    return 0;
}
int mycdev_open(struct inode *inode, struct file *file)
{
    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,
};
 
//中断处理函数
irqreturn_t irq_handler(int irq,void *dev)
{
    gpiod_set_value(desc,!gpiod_get_value(desc));
    if(number=='0')
    {
        number='1';
        condition=1;
        wake_up_interruptible(&head);
 
    }else
    {
        number='0';
        condition=1;
        wake_up_interruptible(&head);
    }
    
    return IRQ_HANDLED;
}
 
//platfom总线设置
int pdrv_probe(struct platform_device *pdr)
{
    int ret;
    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;
    }
    irqno=platform_get_irq(pdr,0);
    if(irqno<0)
    {
        printk("获取资源失败\n");
        return irqno;      
    }
    printk("%#x  %d\n",res->start,irqno);
    //获取gpio编号
    desc=gpiod_get_from_of_node(pdr->dev.of_node,"led1",0,GPIOD_OUT_LOW,NULL);
    if(IS_ERR(desc))
    {
        printk("获取GPIO编号失败\n");
        return PTR_ERR(desc);
    }
 
    //注册软中断号
    ret=request_irq(irqno,irq_handler,IRQF_TRIGGER_FALLING,"key2——inte",NULL);
    if(ret)
    {
        printk("注册中断号失败\n");
        return ret;
    }
    printk("注册中断号成功\n");
 
    condition=0;
    init_waitqueue_head(&head);
 
    return 0;
}
 
int pdrv_remove(struct platform_device *pdrv)
{
    free_irq(irqno,NULL);
    gpiod_set_value(desc,0);
    gpiod_put(desc);
    printk("%s:%d\n",__FILE__,__LINE__);
    return 0;
}
 
//定义compatible表
struct of_device_id oftable[]=
{
    {.compatible="hqyj,hello2"},
    {},
};
 
MODULE_DEVICE_TABLE(of,oftable);
struct platform_driver pdrv={
    .probe=pdrv_probe,
    .remove=pdrv_remove,
    .driver={
        .name="test1",
        .of_match_table=oftable,
    },
};
 
 
static int __init mycdev_init(void)
{
     int ret,i;
    //注册设备驱动
    //1,分配设备驱动对象
    cdev=cdev_alloc();
    if(NULL==cdev)
    {
        printk("申请驱动对象空间失败\n");
        ret = -ENOMEM;
        goto ERR1;
        //return -ENOMEM;
    }
    //2，初始化对象
    cdev_init(cdev,&fops);
    //3，设备号的申请
    ret=alloc_chrdev_region(&dev1,0,3,"LED");
    if(ret != 0)
    {
        printk("申请设备号失败\n");
        goto ERR2;
    }
    major = MAJOR(dev1);
    minor = MINOR(dev1);
    printk("动态设备号申请成功\n");
    //4，注册字符设备驱动
    ret=cdev_add(cdev,dev1,3);
    if(ret !=0)
    {
        printk("注册设备驱动失败\n");
        goto ERR3;
    }
    printk("注册字符设备驱动成功：%d\n",dev1);
 
    //5，自动创建设备节点
    //创建目录
    cls=class_create(THIS_MODULE,"LED");
    if(IS_ERR(cls))
    {
        printk("向上提交目录失败\n");
        goto ERR4;
    }
    printk("向上提交目录成功\n");
    //创建设备节点  3次
    for(i=0;i<3;i++)
    {
        dev=device_create(cls,NULL,MKDEV(major,i),NULL,"myled%d",i);
        if(IS_ERR(dev))
        {
            printk("向上提交节点失败\n");
            ret = PTR_ERR(dev);
            goto ERR5;
        }
    }
    printk("向上提交节点成功\n");
    platform_driver_register(&pdrv);
    return 0;
 
    ERR5:
    for(--i;i>=0;i--)
    {
        device_destroy(cls,MKDEV(major,i));
    }
    class_destroy(cls);
    ERR4:
    cdev_del(cdev);
    ERR3:
    unregister_chrdev_region(dev1,3);
    ERR2:
    kfree(cdev);
    ERR1:
    return ret;
}
static void __exit mycdev_exit(void)
{
    int i;
    platform_driver_unregister(&pdrv);
 
    for(i=0;i<3;i++)
    {
        device_destroy(cls,MKDEV(major,i));
    }
    
    //销毁目录
    class_destroy(cls);
 
    //2，注销字符设备驱动
    cdev_del(cdev);
    //3,释放设备号
    unregister_chrdev_region(dev1,3);
    //4，释放动态申请的空间
    kfree(cdev);
 
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");