基于i.MX6ULL的掉電檢測設計與軟件測試

基于i.MX6ULL平臺設計實現掉電檢測功能，首先選擇一路IO，利用IO電平變化觸發中斷，在編寫驅動時捕獲該路GPIO的中斷，然后在中斷響應函數中發送信號通知應用程序掉電發生了。

圖 1.1掉電信號IO

驅動代碼:

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#define power_MAJOR 200

static struct class *my_class;

static struct fasync_struct *fasync_queue; //異步通知隊列

#define GPIO_NUM 1 //中斷引腳為：GPIO1_1

static unsigned int irq_num;

/*打開 */

int power_open(struct inode *inode,struct file *filp){

return 0;

}

/*關閉 */

int power_release(struct inode *inode,struct file *filp){

return 0;

}

ssize_t power_read(struct file *filp,char __user *buf,size_t count,loff_t *f_pos){

return count;

}

ssize_t power_write(struct file *file,const char __user *buf,size_t count,loff_t *f_pos){

return count;

}

static int my_fasync(int fd, struct file * filp, int on)

{

int retval;

retval=fasync_helper(fd,filp,on,&fasync_queue);

/*將該設備登記到fasync_queue隊列中去*/

if(retval<0)

return retval;

return 0;

}

static const struct file_operations simple_fops={

.owner=THIS_MODULE,

.open=power_open,

.release=power_release,

.read=power_read,

.write=power_write,

.fasync=my_fasync,

};

/*在中斷服務函數中向應用層發送消息-異步通知 */

static irqreturn_t irq_callback (int irqno, void *dev_id){

printk("irq power-detect working !\n");

if (fasync_queue) {

kill_fasync(&fasync_queue, SIGIO, POLL_IN);

}

return IRQ_HANDLED;

}

int power_init_module(void){

int rtn;

int ret;

/*注冊設備驅動 */

ret = register_chrdev(power_MAJOR,"power-detect-test",&simple_fops);

if(ret<0){

printk("Unable to register character device %d!/n",ret);

return ret;

}

/*自動創建設備節點 */

my_class = class_create(THIS_MODULE, "my_class");

device_create(my_class, NULL, MKDEV(power_MAJOR, 0), NULL,"powerdetect");

/*gpio申請*/

rtn = gpio_request(GPIO_NUM, "my_irq");

if(rtn!=0){

printk("my_irq irq pin request io failed.\n");

}

rtn = gpio_direction_input(GPIO_NUM);

if(rtn<0){

printk("gpio_direction_input() failed !\n");

}

/*獲取gpio中斷號*/

irq_num = gpio_to_irq(GPIO_NUM);

/*GPIO中斷服務函數注冊，*/ /*下降沿觸發*/

rtn = request_irq(irq_num, irq_callback,IRQF_TRIGGER_FALLING,"my_irq", NULL);

if (rtn<0) {

printk("my_irq request irq false\n");

} else {

printk("my_irq request irq success: %d\n",irq_num);

}

printk("module_init sucessful!!!\n");

return 0;

}

/*卸載 */

void power_cleanup_module(void){

/*卸載相應的設備驅動 */

unregister_chrdev(power_MAJOR,"power-detect-test");

device_destroy(my_class,MKDEV(power_MAJOR, 0));

class_destroy(my_class);

/*釋放GPIO*/

gpio_free(GPIO_NUM);

printk("module_exit sucessful!!!\n");

}

/*宏實現 */

module_init(power_init_module);

module_exit(power_cleanup_module);

/*開源許可聲明 */

MODULE_LICENSE("GPL");

MODULE_AUTHOR("Zou");

應用代碼:

#include

#include

#include

#include

#include

#include

static int fd;

/*內核產生異步通知,調用該應用層函數處理 */

void sigterm_handler(int signo)

{

printf("app irq work !!!\n");

}

int main(void)

{

int oflags;

fd=open("/dev/powerdetect",O_RDWR); //打開設備文件

/*啟動異步通知信號驅動機制 */

signal(SIGIO, sigterm_handler);

fcntl(fd, F_SETOWN, getpid());

oflags = fcntl(fd, F_GETFL);

fcntl(fd, F_SETFL, oflags | FASYNC);

/*建立一個死循環，防止程序結束 */

while(1)

{

printf("sleep\n");

usleep(200000); //2ms

}

close(fd);

return 0;

}

將驅動編譯成模塊，上電加載并執行應用程序后，將電壓緩慢下調至掉電臨界點。觸發GPIO下降沿中斷，并提供應用程序掉電信號。

圖1..2掉電檢測