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基于i.MX6ULL的掉电检测设计与软件测试 基于i.MX6ULL平台设计实现掉电检测功能，首先选择一路IO，利用IO电平变化触发中断，在编写驱动时捕获该路GPIO的中断，然后在中断响应函数中发送信号通知应用程序掉电发生了。 图1.1掉电信号IO 驱动代码: #include<linux/module.h> #include<linux/init.h> #include<linux/types.h> #include<linux/fs.h> #include<linux/mm.h> #include<linux/cdev.h> #include<linux/errno.h> #include<linux/sched.h> #include<linux/device.h> #include<asm/io.h> #include<asm/switch_to.h> #include<asm/uaccess.h>
#include<asm/gpio.h> #include<linux/interrupt.h> #include<linux/irq.h>
#definepower_MAJOR 200
staticstruct class *my_class; staticstruct fasync_struct *fasync_queue; //异步通知队列
#defineGPIO_NUM 1 //中断引脚为：GPIO1_1 staticunsigned int irq_num;
/* 打开 */ intpower_open(struct inode *inode,struct file *filp){ return 0;
}
/* 关闭 */ intpower_release(struct inode *inode,struct file *filp){ return 0; }
ssize_tpower_read(struct file *filp,char __user *buf,size_t count,loff_t *f_pos){
return count; }
ssize_tpower_write(struct file *file,const char __user *buf,size_t count,loff_t*f_pos){
return count; }
staticint my_fasync(int fd, struct file * filp, int on) { int retval; retval=fasync_helper(fd,filp,on,&fasync_queue); /*将该设备登记到fasync_queue队列中去*/ if(retval<0) return retval; return 0; }
staticconst struct file_operations simple_fops={ .owner=THIS_MODULE, .open=power_open, .release=power_release, .read=power_read, .write=power_write, .fasync=my_fasync, };
/* 在中断服务函数中向应用层发送消息-异步通知 */ staticirqreturn_t irq_callback (int irqno, void *dev_id){ printk("irq power-detectworking !\n"); if (fasync_queue) { kill_fasync(&fasync_queue, SIGIO,POLL_IN); } return IRQ_HANDLED; }
intpower_init_module(void){ int rtn; int ret; /* 注册设备驱动 */ ret =register_chrdev(power_MAJOR,"power-detect-test",&simple_fops); if(ret<0){ printk("Unable toregister character device %d!/n",ret); return ret; }
/* 自动创建设备节点 */ my_class = class_create(THIS_MODULE,"my_class"); device_create(my_class, NULL,MKDEV(power_MAJOR, 0), NULL,"powerdetect");
/*gpio申请*/ rtn = gpio_request(GPIO_NUM,"my_irq"); if(rtn!=0){ printk("my_irq irq pinrequest io failed.\n"); } rtn = gpio_direction_input(GPIO_NUM); if(rtn<0){ printk("gpio_direction_input()failed !\n"); } /*获取gpio中断号*/ irq_num = gpio_to_irq(GPIO_NUM);
/*GPIO中断服务函数注册，*/ /*下降沿触发*/ rtn = request_irq(irq_num,irq_callback,IRQF_TRIGGER_FALLING,"my_irq", NULL); if (rtn<0) { printk("my_irq requestirq false\n"); } else { printk("my_irq requestirq success: %d\n",irq_num); }
printk("module_initsucessful!!!\n"); return 0; }
/* 卸载 */ voidpower_cleanup_module(void){ /* 卸载相应的设备驱动 */ unregister_chrdev(power_MAJOR,"power-detect-test"); device_destroy(my_class,MKDEV(power_MAJOR,0)); class_destroy(my_class);
/*释放GPIO*/ gpio_free(GPIO_NUM);
printk("module_exitsucessful!!!\n"); }
/* 宏实现 */ module_init(power_init_module); module_exit(power_cleanup_module);
/* 开源许可声明 */ MODULE_LICENSE("GPL"); MODULE_AUTHOR("Zou"); 应用代码: #include<stdio.h> #include<fcntl.h> #include<stdlib.h> #include<signal.h> #include<unistd.h> #include<fcntl.h>
staticint fd;
/* 内核产生异步通知,调用该应用层函数处理 */ voidsigterm_handler(int signo) { printf("app irq work !!!\n"); }
intmain(void) { int oflags;
fd=open("/dev/powerdetect",O_RDWR); //打开设备文件
/* 启动异步通知信号驱动机制 */ signal(SIGIO, sigterm_handler); fcntl(fd, F_SETOWN, getpid()); oflags = fcntl(fd, F_GETFL); fcntl(fd, F_SETFL, oflags | FASYNC);
/*建立一个死循环，防止程序结束 */ while(1) { printf("sleep\n"); usleep(200000); //2ms }
close(fd); return 0; } 将驱动编译成模块，上电加载并执行应用程序后，将电压缓慢下调至掉电临界点。触发GPIO下降沿中断，并提供应用程序掉电信号。 ![]() 图1..2掉电检测
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