目录

一、什么是中断

二、中断处理原理

三、中断接口

3.1 中断申请

3.2 中断释放

3.3 中断处理函数原型

四、按键驱动

---

一、什么是中断

一种硬件上的通知机制，用来通知CPU发生了某种需要立即处理的事件

分为：

1. 内部中断  CPU执行程序的过程中，发生的一些硬件出错、运算出错事件（如分母为0、溢出等等），不可屏蔽

2. 外部中断  外设发生某种情况，通过一个引脚的高、低电平变化来通知CPU （如外设产生了数据、某种处理完毕等等）

二、中断处理原理

（向量中断：在一块内存中每个地址对应一个中断.arm中异常是向量形式的。中断是非向量形式的中断是7种异常的一种

非向量中断：只有一个中断接口，在中断处理程序中有很多分处理函数，比如exynos4412）

（哪种中断好像和硬件有关）

任何一种中断产生，CPU都会暂停当前执行的程序，跳转到内存固定位置执行一段程序，该程序被称为总的中断服务程序，在该程序中区分中断源，然后进一步调用该中断源对应的处理函数。

中断源对应的处理函数被称为分中断处理程序，一般每一个分中断处理程序对应一个外设产生的中断

写驱动时，如果外设有中断，则需要编写一个函数（分中断处理程序）来处理这种中断

三、中断接口

3.1 中断申请

```cint request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,const char *name, void *dev)/*参数：irq：所申请的中断号handler：该中断号对应的中断处理函数flags：中断触发方式或处理方式触发方式：IRQF_TRIGGER_NONE      //无触发IRQF_TRIGGER_RISING    //上升沿触发IRQF_TRIGGER_FALLING  //下降沿触发IRQF_TRIGGER_HIGH   //高电平触发IRQF_TRIGGER_LOW        //低电平触发处理方式：IRQF_DISABLED        //用于快速中断，处理中屏蔽所有中断IRQF_SHARED       //共享中断name：中断名 /proc/interruptsdev：传递给中断例程的参数，共享中断时用于区分那个设备，一般为对应设备的结构体地址，无共享中断时写NULL返回值：成功：0 失败：错误码*/```

3.2 中断释放

```cvoid free_irq(unsigned int irq, void *dev_id)；/*功能：释放中断号参数：irq：设备号dev_id：共享中断时用于区分那个设备一般强转成设备号，无共享中断时写NULL*/```

3.3 中断处理函数原型

```ctypedef irqreturn_t (*irq_handler_t)(int, void *);/*参数：int：中断号void*:对应的申请中断时的dev_id返回值：typedef enum irqreturn irqreturn_t; //中断返回值类型enum irqreturn {IRQ_NONE    = (0 << 0),IRQ_HANDLED = (1 << 0),IRQ_WAKE_THREAD = (1 << 1),};返回IRQ_HANDLED表示处理完了,返回IRQ_NONE在共享中断表示不处理*/```

四、按键驱动

按键原理图：

interrupts中第一个数据是 上面紫色框一致的25是第1个24是第0个所以是1，3是11所以上升沿也触发下降沿也触发。

exynos4412-fs4412.dts中增加节点

```

mykey2_node {

    compatible = "mykey2,key2";

    key2-gpio = <&gpx1 1 0>;

    interrupt-parent = <&gpx1>;

    interrupts = <1 3>;

};

```

申请中断做好要在初始化函数左后做，不然可以会导致有些东西没准备好

由于是按键所以要设置防抖，异常上下文是不能msleep的这里延时使用mdelay

 

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/cdev.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <asm/uaccess.h>#include "fs4412_key.h"int major = 11;
int minor = 0;
int fs4412key2_num  = 1;struct fs4412key2_dev
{struct cdev mydev;int gpio;int irqno;struct keyvalue data;int newflag;spinlock_t lock;wait_queue_head_t rq;
};struct fs4412key2_dev *pgmydev = NULL;int fs4412key2_open(struct inode *pnode,struct file *pfile)
{pfile->private_data =(void *) (container_of(pnode->i_cdev,struct fs4412key2_dev,mydev));return 0;
}int fs4412key2_close(struct inode *pnode,struct file *pfile)
{return 0;
}ssize_t fs4412key2_read(struct file *pfile,char __user *puser,size_t count,loff_t *p_pos)
{struct fs4412key2_dev *pmydev = (struct fs4412key2_dev *)pfile->private_data;int size = 0;int ret = 0;if(count < sizeof(struct keyvalue)){printk("expect read size is invalid\n");return -1;}spin_lock(&pmydev->lock);if(!pmydev->newflag){if(pfile->f_flags & O_NONBLOCK){//非阻塞spin_unlock(&pmydev->lock);printk("O_NONBLOCK No Data Read\n");return -1;}else{//阻塞spin_unlock(&pmydev->lock);ret = wait_event_interruptible(pmydev->rq,pmydev->newflag == 1);if(ret){printk("Wake up by signal\n");return -ERESTARTSYS;}spin_lock(&pmydev->lock);}}if(count > sizeof(struct keyvalue)){size = sizeof(struct keyvalue);}else{size = count;}ret = copy_to_user(puser,&pmydev->data,size);if(ret){spin_unlock(&pmydev->lock);printk("copy_to_user failed\n");return -1;}pmydev->newflag = 0;spin_unlock(&pmydev->lock);return size;
}unsigned int fs4412key2_poll(struct file *pfile,poll_table *ptb)
{struct fs4412key2_dev *pmydev = (struct fs4412key2_dev *)pfile->private_data;unsigned int mask = 0;poll_wait(pfile,&pmydev->rq,ptb);spin_lock(&pmydev->lock);if(pmydev->newflag){mask |= POLLIN | POLLRDNORM;}spin_unlock(&pmydev->lock);return mask;
}struct file_operations myops = {.owner = THIS_MODULE,.open = fs4412key2_open,.release = fs4412key2_close,.read = fs4412key2_read,.poll = fs4412key2_poll,
};irqreturn_t key2_irq_handle(int no,void *arg)
{struct fs4412key2_dev *pmydev = (struct fs4412key2_dev *)arg;int status1 = 0;int status2 = 0;int status = 0;status1 = gpio_get_value(pmydev->gpio);mdelay(1);status2 = gpio_get_value(pmydev->gpio);if(status1 != status2){return IRQ_NONE;}status = status1;spin_lock(&pmydev->lock);if(status == pmydev->data.status){spin_unlock(&pmydev->lock);return IRQ_NONE;}pmydev->data.code = KEY2;pmydev->data.status = status;pmydev->newflag = 1;spin_unlock(&pmydev->lock);wake_up(&pmydev->rq);return IRQ_HANDLED;
}int __init fs4412key2_init(void)
{int ret = 0;dev_t devno = MKDEV(major,minor);struct device_node *pnode = NULL;pnode = of_find_node_by_path("/mykey2_node");if(NULL == pnode){printk("find node failed\n");return -1;}pgmydev = (struct fs4412key2_dev *)kmalloc(sizeof(struct fs4412key2_dev),GFP_KERNEL);if(NULL == pgmydev){printk("kmallc for struct fs4412key2_dev failed\n");return -1;}pgmydev->gpio = of_get_named_gpio(pnode,"key2-gpio",0);pgmydev->irqno = irq_of_parse_and_map(pnode,0);ret = register_chrdev_region(devno,fs4412key2_num,"fs4412key2");if(ret){ret = alloc_chrdev_region(&devno,minor,fs4412key2_num,"fs4412key2");if(ret){kfree(pgmydev);pgmydev = NULL;printk("get devno failed\n");return -1;}major = MAJOR(devno);}cdev_init(&pgmydev->mydev,&myops);pgmydev->mydev.owner = THIS_MODULE;cdev_add(&pgmydev->mydev,devno,fs4412key2_num);init_waitqueue_head(&pgmydev->rq);spin_lock_init(&pgmydev->lock);ret = request_irq(pgmydev->irqno,key2_irq_handle,IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,"fs4412key2",pgmydev);if(ret){printk("request_irq failed\n");cdev_del(&pgmydev->mydev);kfree(pgmydev);pgmydev = NULL;unregister_chrdev_region(devno,fs4412key2_num);return -1;}return 0;
}void __exit fs4412key2_exit(void)
{dev_t devno = MKDEV(major,minor);free_irq(pgmydev->irqno,pgmydev);cdev_del(&pgmydev->mydev);unregister_chrdev_region(devno,fs4412key2_num);kfree(pgmydev);pgmydev = NULL;
}MODULE_LICENSE("GPL");module_init(fs4412key2_init);
module_exit(fs4412key2_exit);

 

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>#include <stdio.h>#include "fs4412_key.h"int main(int argc,char *argv[])
{int fd = -1;struct keyvalue keydata = {0};int ret = 0;if(argc < 2){printf("The argument is too few\n");return 1;}fd = open(argv[1],O_RDONLY);if(fd < 0){printf("open %s failed\n",argv[1]);return 3;}while((ret = read(fd,&keydata,sizeof(keydata))) == sizeof(keydata)){if(keydata.status == KEY_DOWN){printf("Key2 is down!\n");}else{printf("Key2 is up!\n");}}close(fd);fd = -1;return 0;
}

根据key2的驱动改写key3

 

 

 

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/cdev.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <asm/uaccess.h>#include "fs4412_key.h"int major = 11;
int minor = 0;
int fs4412key3_num  = 1;struct fs4412key3_dev
{struct cdev mydev;int gpio;int irqno;struct keyvalue data;int newflag;spinlock_t lock;wait_queue_head_t rq;
};struct fs4412key3_dev *pgmydev = NULL;int fs4412key3_open(struct inode *pnode,struct file *pfile)
{pfile->private_data =(void *) (container_of(pnode->i_cdev,struct fs4412key3_dev,mydev));return 0;
}int fs4412key3_close(struct inode *pnode,struct file *pfile)
{return 0;
}ssize_t fs4412key3_read(struct file *pfile,char __user *puser,size_t count,loff_t *p_pos)
{struct fs4412key3_dev *pmydev = (struct fs4412key3_dev *)pfile->private_data;int size = 0;int ret = 0;if(count < sizeof(struct keyvalue)){printk("expect read size is invalid\n");return -1;}spin_lock(&pmydev->lock);if(!pmydev->newflag){if(pfile->f_flags & O_NONBLOCK){//非阻塞spin_unlock(&pmydev->lock);printk("O_NONBLOCK No Data Read\n");return -1;}else{//阻塞spin_unlock(&pmydev->lock);ret = wait_event_interruptible(pmydev->rq,pmydev->newflag == 1);if(ret){printk("Wake up by signal\n");return -ERESTARTSYS;}spin_lock(&pmydev->lock);}}if(count > sizeof(struct keyvalue)){size = sizeof(struct keyvalue);}else{size = count;}ret = copy_to_user(puser,&pmydev->data,size);if(ret){spin_unlock(&pmydev->lock);printk("copy_to_user failed\n");return -1;}pmydev->newflag = 0;spin_unlock(&pmydev->lock);return size;
}unsigned int fs4412key3_poll(struct file *pfile,poll_table *ptb)
{struct fs4412key3_dev *pmydev = (struct fs4412key3_dev *)pfile->private_data;unsigned int mask = 0;poll_wait(pfile,&pmydev->rq,ptb);spin_lock(&pmydev->lock);if(pmydev->newflag){mask |= POLLIN | POLLRDNORM;}spin_unlock(&pmydev->lock);return mask;
}struct file_operations myops = {.owner = THIS_MODULE,.open = fs4412key3_open,.release = fs4412key3_close,.read = fs4412key3_read,.poll = fs4412key3_poll,
};irqreturn_t key3_irq_handle(int no,void *arg)
{struct fs4412key3_dev *pmydev = (struct fs4412key3_dev *)arg;int status1 = 0;int status2 = 0;int status = 0;status1 = gpio_get_value(pmydev->gpio);mdelay(1);status2 = gpio_get_value(pmydev->gpio);if(status1 != status2){return IRQ_NONE;}status = status1;spin_lock(&pmydev->lock);if(status == pmydev->data.status){spin_unlock(&pmydev->lock);return IRQ_NONE;}pmydev->data.code = KEY3;pmydev->data.status = status;pmydev->newflag = 1;spin_unlock(&pmydev->lock);wake_up(&pmydev->rq);return IRQ_HANDLED;
}int __init fs4412key3_init(void)
{int ret = 0;dev_t devno = MKDEV(major,minor);struct device_node *pnode = NULL;pnode = of_find_node_by_path("/mykey3_node");if(NULL == pnode){printk("find node failed\n");return -1;}pgmydev = (struct fs4412key3_dev *)kmalloc(sizeof(struct fs4412key3_dev),GFP_KERNEL);if(NULL == pgmydev){printk("kmallc for struct fs4412key3_dev failed\n");return -1;}pgmydev->gpio = of_get_named_gpio(pnode,"key3-gpio",0);pgmydev->irqno = irq_of_parse_and_map(pnode,0);ret = register_chrdev_region(devno,fs4412key3_num,"fs4412key3");if(ret){ret = alloc_chrdev_region(&devno,minor,fs4412key3_num,"fs4412key3");if(ret){kfree(pgmydev);pgmydev = NULL;printk("get devno failed\n");return -1;}major = MAJOR(devno);}cdev_init(&pgmydev->mydev,&myops);pgmydev->mydev.owner = THIS_MODULE;cdev_add(&pgmydev->mydev,devno,fs4412key3_num);init_waitqueue_head(&pgmydev->rq);spin_lock_init(&pgmydev->lock);ret = request_irq(pgmydev->irqno,key3_irq_handle,IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,"fs4412key3",pgmydev);if(ret){printk("request_irq failed\n");cdev_del(&pgmydev->mydev);kfree(pgmydev);pgmydev = NULL;unregister_chrdev_region(devno,fs4412key3_num);return -1;}return 0;
}void __exit fs4412key3_exit(void)
{dev_t devno = MKDEV(major,minor);free_irq(pgmydev->irqno,pgmydev);cdev_del(&pgmydev->mydev);unregister_chrdev_region(devno,fs4412key3_num);kfree(pgmydev);pgmydev = NULL;
}MODULE_LICENSE("GPL");module_init(fs4412key3_init);
module_exit(fs4412key3_exit);

 

#ifndef FS4412_KEY_H
#define FS4412_KEY_Henum KEYCODE
{KEY2 = 1002,KEY3 = 1003,KEY4,
};enum KEY_STATUS
{KEY_DOWN = 0,KEY_UP,
};struct keyvalue
{int code;//which KEYint status;
};#endif

测试代码修改一下打印就行。