19、IMX6ULL学习笔记-linux设备树之按键中断

一、原理图

二、中断表

三、设备树

三、驱动程序

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/string.h>
#include <linux/irq.h>
#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/interrupt.h>
#define DeviceName 		"devicetree-key0-interrupt" //设备驱动名称
#define DeviceNodes 	1 					  	 //设备节点个数
#define KEY_NUM 		0X01             
#define KEY0VALUE       0X01
#define INVAKEY         0XFF
struct irq_keydesc{
    int gpio_num;           /* io编号 */
    int irq_num;            /* 中断号 */
    unsigned char value;    /* 键值 */
    char name[25];          /* 名字 */
    irqreturn_t (*handler) (int, void *);  /* 中断处理函数 */
};
/* 定义一个设备结构体 */
struct mod_struct {
	dev_t devid;			     /* 设备号 */
	int major;				     /* 主设备号 */
	int minor;				     /* 次设备号 */
	struct cdev cdev;		     /* cdev */
	struct class *class;	  	 /* 类 */
	struct device *device;	 	 /* 设备 */
	struct device_node *nd;  	 /* 设备节点 */
	struct irq_keydesc irqkey0;  /* 按键中断 */
	struct timer_list timer;	 /* 内核定时器 */
	atomic_t keyvalue;			 /* 原子变量1->整形*/
    atomic_t releasekey;		 /* 原子变量2->整形*/
};
struct mod_struct mod_device;	 /* 定义一个设备 */
/*
 * @description		: 打开设备
 * @param - inode 	: 传递给驱动的inode
 * @param - filp 	: 设备文件，file结构体有个叫做private_data的成员变量
 * 					  一般在open的时候将private_data指向设备结构体。
 * @return 			: 0 成功;其他 失败
 */
static int key0_interrupt_open(struct inode *inode, struct file *filp)
{
	filp->private_data = &mod_device; /* 设置私有数据 */
	return 0;
}
/*
 * @description		: 从设备读取数据 
 * @param - filp 	: 要打开的设备文件(文件描述符)
 * @param - buf 	: 返回给用户空间的数据缓冲区
 * @param - cnt 	: 要读取的数据长度
 * @param - offt 	: 相对于文件首地址的偏移
 * @return 			: 读取的字节数，如果为负值，表示读取失败
 */
static ssize_t key0_interrupt_read(struct file *filp, char __user *buf, size_t cnt, loff_t *offt)
{
    int ret = 0;
    unsigned char keyvalue;
    unsigned char releasekey;
    struct mod_struct *dev = filp->private_data;
    keyvalue = atomic_read(&dev->keyvalue);
    releasekey = atomic_read(&dev->releasekey);
    if(releasekey) {        /* 有效按键 */
        if(keyvalue & 0x80) {
            keyvalue &= ~0x80;
            ret = copy_to_user(buf, &keyvalue, sizeof(keyvalue));
        } else {
            goto data_error;
        }
        atomic_set(&dev->releasekey, 0); /* 按下标志清零 */
    } else {
        goto data_error;
       }
    return ret;
data_error:
    return -EINVAL;
}
/*
 * @description		: 向设备写数据 
 * @param - filp 	: 设备文件，表示打开的文件描述符
 * @param - buf 	: 要写给设备写入的数据
 * @param - cnt 	: 要写入的数据长度
 * @param - offt 	: 相对于文件首地址的偏移
 * @return 			: 写入的字节数，如果为负值，表示写入失败
 */
static ssize_t key0_interrupt_write(struct file *filp, const char __user *buf,size_t cnt, loff_t *offt)
{
	return 0;
}
/*
 * @description		: 关闭/释放设备
 * @param - filp 	: 要关闭的设备文件(文件描述符)
 * @return 			: 0 成功;其他 失败
 */
static int key0_interrupt_release(struct inode *inode, struct file *filp)
{
	return 0;
}
/* 设备操作函数 */
static struct file_operations beep_fops = {
	.owner    	=  THIS_MODULE,
	.open     	=  key0_interrupt_open,
	.read     	=  key0_interrupt_read,
	.write    	=  key0_interrupt_write,
	.release  	=  key0_interrupt_release,
};
/* 按键中断处理函数 */
static irqreturn_t key0_handler(int irq, void *dev_id)
{
	struct mod_struct *dev = dev_id;
	dev->timer.data = (volatile long)dev_id;
	mod_timer(&dev->timer, jiffies + msecs_to_jiffies(20)); /* 20ms定时 */
	return IRQ_HANDLED;
}
/* 定时器处理函数 */
static void timer_func(unsigned long arg) {
    int value = 0;
    struct mod_struct *dev = (struct mod_struct*)arg;
    value = gpio_get_value(dev->irqkey0.gpio_num);
    if(value == 0)   {          /* 按下 */
        atomic_set(&dev->keyvalue, dev->irqkey0.value);/*=0x01*/
    } else if(value == 1) {     /* 释放 */
        atomic_set(&dev->keyvalue, 0X80 | (dev->irqkey0.value));
        atomic_set(&dev->releasekey, 1);  /* 完成的按键过程 */
    }
}
/*
 * @description	: 按键初始化函数
 * @param 		: dev
 * @return 		: 无
 */
static int key_init(struct mod_struct *dev)
{
	int ret = 0;
	/* 1、获取设备节点：/devicetree-leds-pincrl */
	dev->nd = of_find_node_by_path("/devicetree-key0-interrupt");
	if(dev->nd == NULL) {
			printk("devicetree-key0-interrupt node not find!\r\n");
			ret = -EINVAL;
			goto fail_fd;
	} else {
		printk("devicetree-key0-interrupt node find!\r\n");
	}
	/* 2、从设备节点下的led-gpio属性里获取gpio编号 */
	dev->irqkey0.gpio_num = of_get_named_gpio(dev->nd,"key-gpio", 0);
	if(dev->irqkey0.gpio_num < 0) {
			printk("can't get key-gpio\r\n");
			ret = -EINVAL;
			goto fail_gpio;
	}
	printk("key-gpio num = %d\r\n", dev->irqkey0.gpio_num);
	/*3、申请gpio(检查是否被占用)*/
	sprintf(dev->irqkey0.name,"%s","key0-gpio-interrupt");
	ret = gpio_request(dev->irqkey0.gpio_num,dev->irqkey0.name);
	if(ret)
	{
		ret = -EBUSY;
		printk("IO %d busy,can't request!\r\n",dev->irqkey0.gpio_num);
		goto fail_ioreq;
	}
	/*4、设置key0为输入 */
	ret = gpio_direction_input(dev->irqkey0.gpio_num);
	if(ret < 0) {
			printk("can't set gpio!\r\n");
			goto fail_ioset;
	}
	/*5、根据IO编号获取其中断号*/
	dev->irqkey0.irq_num=gpio_to_irq(dev->irqkey0.gpio_num);
#if 0
	dev->irqkey0.irq_num = irq_of_parse_and_map(dev->nd,0);
#endif
	/*6、设置中断函数*/
	dev->irqkey0.handler = key0_handler;
    dev->irqkey0.value  = KEY0VALUE;
	/*7、注册中断*/
	ret = request_irq(dev->irqkey0.irq_num,
					  dev->irqkey0.handler,
					  IRQF_TRIGGER_RISING|IRQF_TRIGGER_FALLING,
					  dev->irqkey0.name,
					  &mod_device);
	if(ret){
		printk("irq %d request failed!\r\n", dev->irqkey0.irq_num);
		goto fail_irq;
	}
	/*8、初始化定时器*/
	init_timer(&mod_device.timer);
    mod_device.timer.function = timer_func;
	return 0;
fail_irq:
fail_ioset:
	gpio_free(dev->irqkey0.gpio_num);
fail_ioreq:
fail_gpio:
fail_fd:
	return ret;
}
/*
 * @description	: 驱动出口函数
 * @param 		: 无
 * @return 		: 无
 */
static int __init key0_interrupt_init(void)
{
	int ret = 0;
/*一、 注册字符设备驱动 */
	/* 1、创建设备号 */
	if (mod_device.major)
	{		
		mod_device.devid = MKDEV(mod_device.major,0);//设备号起始点(major,0)
		//设备号起始点开始，申请DeviceNodes个设备号
		ret = register_chrdev_region(mod_device.devid,DeviceNodes,DeviceName);
	} 
	else {
		ret = alloc_chrdev_region(&mod_device.devid,0,DeviceNodes,DeviceName);	/* 申请设备号 */
		mod_device.major = MAJOR(mod_device.devid);	/* 获取分配号的主设备号 */
		mod_device.minor = MINOR(mod_device.devid);	/* 获取分配号的次设备号 */	
	}
	if(ret < 0){ printk("设备号申请失败\r\n");goto fail_chrdev; }
	printk("mod_device major=%d,minor=%d\r\n",mod_device.major,mod_device.minor);	
	/* 2、初始化cdev并添加cdev */
	mod_device.cdev.owner = THIS_MODULE;
	cdev_init(&mod_device.cdev,&beep_fops);
	ret = cdev_add(&mod_device.cdev,mod_device.devid,DeviceNodes);
	if(ret < 0){ printk("添加cdev失败！\r\n");goto fail_cdev; }
	/* 3、创建类 */
	mod_device.class = class_create(THIS_MODULE,DeviceName);
	if (IS_ERR(mod_device.class)) { ret = PTR_ERR(mod_device.class);goto fail_class; } 
	/* 4、创建设备节点*/
	mod_device.device = device_create(mod_device.class,NULL,mod_device.devid,NULL,"DeviceName");
	if (IS_ERR(mod_device.device)) { ret = PTR_ERR(mod_device.device);goto fail_device; }
	/* 5、初始化IO */
    ret = key_init(&mod_device);
    if(ret < 0) {
        goto fail_keyinit;
    }
	/* 6、初始化原子变量 */
	atomic_set(&mod_device.keyvalue, INVAKEY);/*mod_device.keyvalue=INVAKEY*/
    atomic_set(&mod_device.releasekey, 0);/*mod_device.releasekey=0*/
/*X、模块加载失败处理部分*/
fail_keyinit:
	device_destroy(mod_device.class,mod_device.devid);
fail_device:	
	class_destroy(mod_device.class);
fail_class:	
	cdev_del(&mod_device.cdev);
fail_cdev:
	unregister_chrdev_region(mod_device.devid,DeviceNodes);
fail_chrdev:
	return ret;
}
/*
 * @description	: 驱动出口函数
 * @param 		: 无
 * @return 		: 无
 */
static void __exit key0_interrupt_exit(void)/*按照相反顺序注销*/
{
	/*1、释放中断*/
	free_irq(mod_device.irqkey0.irq_num, &mod_device);
	/*2、内核定定时器注销部分*/
	del_timer_sync(&mod_device.timer);/* 删除timer */
	/*3、LED设备注销部分*/
	gpio_free(mod_device.irqkey0.gpio_num);/*注销gpio*/		
	/*4、设备驱动注销部分*/			
	device_destroy(mod_device.class,mod_device.devid);/*注销设备节点*/
	class_destroy(mod_device.class);/*注销类*/
	cdev_del(&mod_device.cdev);/*注销cdev*/
	unregister_chrdev_region(mod_device.devid,DeviceNodes);/*注销chrdev*/
}
module_init(key0_interrupt_init);
module_exit(key0_interrupt_exit);
MODULE_LICENSE("GPL");

四 、APP测试程序

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
/*
 *argc:应用程序参数个数
 *argv[]:具体的参数内容，字符串形式 
 *./imx6uirqAPP  <filename>  
 * ./imx6uirqAPP /dev/mx6uirq
 */
int main(int argc, char *argv[])
{
    int fd, ret;
    char *filename;
    unsigned char data;

    if(argc != 2) {
        printf("Error Usage!\r\n");
        return -1;
    }

    filename = argv[1];

    fd = open(filename, O_RDWR);
    if(fd < 0) {
        printf("file %s open failed!\r\n", filename);
        return -1;
    }
    /* 循环读取 */
    while(1) {
        ret = read(fd, &data, sizeof(data));
        if(ret < 0) {
			
        } else {
            if(data)
                printf("key value = %#x\r\n", data);
        }
    }
    close(fd);
    return 0;
}

五、实验现象

按键按下一次，APP输出一次0x01