按键驱动的恩恩怨怨之同步相互排斥堵塞

发布时间:2017-7-1 11:35:27编辑:www.fx114.net 分享查询网我要评论
本篇文章主要介绍了"按键驱动的恩恩怨怨之同步相互排斥堵塞 ",主要涉及到按键驱动的恩恩怨怨之同步相互排斥堵塞 方面的内容,对于按键驱动的恩恩怨怨之同步相互排斥堵塞 感兴趣的同学可以参考一下。

/* 键值: 按下时, 0x01, 0x02, 0x03, 0x04 *//* 键值: 松开时, 0x81, 0x82, 0x83, 0x84 */static unsigned char key_val;/* * K1,K2,K3,K4相应GPG0。GPG3,GPG5。GPG6 */struct pin_desc pins_desc[4] = { {S3C2410_GPG0, 0x01}, {S3C2410_GPG3, 0x02}, {S3C2410_GPG5, 0x03}, {S3C2410_GPG6, 0x04},};//static atomic_t canopen = ATOMIC_INIT(1); //定义原子变量并初始化为1static DECLARE_MUTEX(button_lock); //定义相互排斥锁/* * 确定按键值 */static irqreturn_t buttons_irq(int irq, void *dev_id) //參数中断号,和ID{ struct pin_desc * pindesc = (struct pin_desc *)dev_id; //?定义一个结构体指针使他的初值为ID unsigned int pinval; pinval = s3c2410_gpio_getpin(pindesc->pin); //系统函数独处引脚值(GPF0) if (pinval) { /* 松开 */ key_val = 0x80 | pindesc->key_val; } else { /* 按下 */ key_val = pindesc->key_val; } ev_press = 1; /* 表示中断发生了 */ wake_up_interruptible(&button_waitq); /* 唤醒休眠的进程 */ //kill_fasync (&button_async, SIGIO, POLL_IN); return IRQ_RETVAL(IRQ_HANDLED);}static int sixth_drv_open(struct inode *inode, struct file *file){#if 0/**刚開始定义为1然后自减变为0返回1。再取非则不执行函数。假设在这个函数没关闭之前又想打开则*先自减变为-1返回0,再去非则变为1,则执行函数。

先自加变为0,然后返回繁忙*/ if (!atomic_dec_and_test(&canopen)) //原子操作,自减操作后測试其是否为0,为0则返回true,否则返回false。 { atomic_inc(&canopen); return -EBUSY; }#endif if (file->f_flags & O_NONBLOCK) { if (down_trylock(&button_lock)) return -EBUSY; } else { /* 获取信号量 */ down(&button_lock); } /* GPG0,GPG3,GPG5。GPG6为中断引脚: EINT8,EINT11,EINT13,EINT14 */ request_irq(IRQ_EINT8, buttons_irq, IRQT_BOTHEDGE, "K1", &pins_desc[0]); request_irq(IRQ_EINT11, buttons_irq, IRQT_BOTHEDGE, "K2", &pins_desc[1]); request_irq(IRQ_EINT13, buttons_irq, IRQT_BOTHEDGE, "K3", &pins_desc[2]); request_irq(IRQ_EINT14, buttons_irq, IRQT_BOTHEDGE, "K4", &pins_desc[3]); return 0;}ssize_t sixth_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos){ if (size != 1) return -EINVAL; if (file->f_flags & O_NONBLOCK) { if (!ev_press) return -EAGAIN; } else { /* 假设没有按键动作, 休眠 */ wait_event_interruptible(button_waitq, ev_press); } /* 假设有按键动作, 返回键值 */ copy_to_user(buf, &key_val, 1); ev_press = 0; return 1;}int sixth_drv_close(struct inode *inode, struct file *file){ //atomic_inc(&canopen); //原子加1 free_irq(IRQ_EINT8, &pins_desc[0]); free_irq(IRQ_EINT11, &pins_desc[1]); free_irq(IRQ_EINT13, &pins_desc[2]); free_irq(IRQ_EINT14, &pins_desc[3]); up(&button_lock); return 0;}# if 0 static unsigned sixth_drv_poll(struct file *file, poll_table *wait){ unsigned int mask = 0; poll_wait(file, &button_waitq, wait); // 不会马上休眠 if (ev_press) mask |= POLLIN | POLLRDNORM; return mask;}#endif# if 0 static int sixth_drv_fasync (int fd, struct file *filp, int on){ printk("driver: sixth_drv_fasync\n"); return fasync_helper (fd, filp, on, &button_async);}#endifstatic struct file_operations sencod_drv_fops = { .owner = THIS_MODULE, /* 这是一个宏,推向编译模块时自己主动创建的__this_module变量 */ .open = sixth_drv_open, .read = sixth_drv_read, .release = sixth_drv_close, //.poll = sixth_drv_poll, //.fasync = sixth_drv_fasync,};int major;static int sixth_drv_init(void){ major = register_chrdev(0, "sixth_drv", &sencod_drv_fops); sixthdrv_class = class_create(THIS_MODULE, "sixth_drv"); sixthdrv_class_dev = class_device_create(sixthdrv_class, NULL, MKDEV(major, 0), NULL, "buttons"); /* /dev/buttons */// gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);// gpfdat = gpfcon + 1; return 0;}static void sixth_drv_exit(void){ unregister_chrdev(major, "sixth_drv"); class_device_unregister(sixthdrv_class_dev); class_destroy(sixthdrv_class);// iounmap(gpfcon); return 0;}module_init(sixth_drv_init);module_exit(sixth_drv_exit);MODULE_LICENSE("GPL");




二.应用程序代码

#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <stdio.h>#include <poll.h>#include <signal.h>#include <sys/types.h>#include <unistd.h>#include <fcntl.h>/* sixthdrvtest   */int fd;#if 0 void my_signal_fun(int signum){	unsigned char key_val;	read(fd, &key_val, 1);	printf("key_val: 0x%x\n", key_val);}#endif int main(int argc, char **argv){	unsigned char key_val;	int ret;	int Oflags;	//signal(SIGIO, my_signal_fun);		fd = open("/dev/buttons", O_RDWR | O_NONBLOCK);  //增加O_NONBLOCK就可以实现非堵塞	if (fd < 0)	{		printf("can't open!\n");		return -1;	}	//fcntl(fd, F_SETOWN, getpid());		//Oflags = fcntl(fd, F_GETFL); 		//fcntl(fd, F_SETFL, Oflags | FASYNC);	while (1)	{		ret = read(fd, &key_val, 1);		printf("key_val: 0x%x, ret = %d\n", key_val, ret);		sleep(5);                                          //单位为秒	}



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