在前面的博文中記錄的都是應用層主動查詢讀取驅動按鍵狀態。驅動可不可以在有信號之后，主動上報通知應用層事件呢？當然可以，linux如此博大精深。我們使用異步通信機制，signal的辦法實現該功能。

所謂的異步，就是進程可以在信號沒到前干別的事情，等到信號到來了，進程就會被內核通知去做相應的信號操作。進程是不知道信號什么時候來的。

First of all,我們學習一下，應用層是怎樣使用signal的。不叨叨，先貼代碼。(show me the fucking code)

我們使用kill 信號編號值 PID 號來傳遞命令給這個應用程序。使用ps查看這個程序的PID號。

?目標：按下按鍵時，驅動通知應用層程序

1：應用程序注冊信號處理函數

2：驅動來主動發出信號

3：發給應用層

4：使用kill_fasync函數發出信號

那么我們的驅動程序跟應用程序該怎么寫呢？show me the fucking code:

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#include <linux/module.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/delay.h> #include <linux/irq.h> #include <asm/uaccess.h> #include <asm/irq.h> #include <asm/io.h> #include <asm/arch/regs-gpio.h> #include <asm/hardware.h> #include <linux/poll.h>static struct class *fifthdrv_class; static struct class_device *fifthdrv_class_dev;volatile unsigned long *gpfcon; volatile unsigned long *gpfdat;volatile unsigned long *gpgcon; volatile unsigned long *gpgdat;static DECLARE_WAIT_QUEUE_HEAD(button_waitq);/* 中斷事件標志, 中斷服務程序將它置1，fifth_drv_read將它清0 */ static volatile int ev_press = 0;static struct fasync_struct *button_async;struct pin_desc{unsigned int pin;unsigned int key_val; };/* 鍵值: 按下時, 0x01, 0x02, 0x03, 0x04 */ /* 鍵值: 松開時, 0x81, 0x82, 0x83, 0x84 */ static unsigned char key_val;struct pin_desc pins_desc[4] = {{S3C2410_GPF0, 0x01},{S3C2410_GPF2, 0x02},{S3C2410_GPG3, 0x03},{S3C2410_GPG11, 0x04}, };/** 確定按鍵值*/ static irqreturn_t buttons_irq(int irq, void *dev_id) {struct pin_desc * pindesc = (struct pin_desc *)dev_id;unsigned int pinval;pinval = s3c2410_gpio_getpin(pindesc->pin);if (pinval){/* 松開 */key_val = 0x80 | pindesc->key_val;}else{/* 按下 */key_val = pindesc->key_val;}ev_press = 1; /* 表示中斷發生了 */wake_up_interruptible(&button_waitq); /* 喚醒休眠的進程 */kill_fasync (&button_async, SIGIO, POLL_IN);return IRQ_RETVAL(IRQ_HANDLED); }static int fifth_drv_open(struct inode *inode, struct file *file) {/* 配置GPF0,2為輸入引腳 *//* 配置GPG3,11為輸入引腳 */request_irq(IRQ_EINT0, buttons_irq, IRQT_BOTHEDGE, "S2", &pins_desc[0]);request_irq(IRQ_EINT2, buttons_irq, IRQT_BOTHEDGE, "S3", &pins_desc[1]);request_irq(IRQ_EINT11, buttons_irq, IRQT_BOTHEDGE, "S4", &pins_desc[2]);request_irq(IRQ_EINT19, buttons_irq, IRQT_BOTHEDGE, "S5", &pins_desc[3]); return 0; }ssize_t fifth_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) {if (size != 1)return -EINVAL;/* 如果沒有按鍵動作, 休眠 */wait_event_interruptible(button_waitq, ev_press);/* 如果有按鍵動作, 返回鍵值 */copy_to_user(buf, &key_val, 1);ev_press = 0;return 1; }int fifth_drv_close(struct inode *inode, struct file *file) {free_irq(IRQ_EINT0, &pins_desc[0]);free_irq(IRQ_EINT2, &pins_desc[1]);free_irq(IRQ_EINT11, &pins_desc[2]);free_irq(IRQ_EINT19, &pins_desc[3]); fifth_drv_fasync (-1,filp,0);

return 0;}static unsigned fifth_drv_poll(struct file *file, poll_table *wait){unsigned int mask = 0;poll_wait(file, &button_waitq, wait); // 不會立即休眠if (ev_press)mask |= POLLIN | POLLRDNORM;return mask;}static int fifth_drv_fasync (int fd, struct file *filp, int on){printk("driver: fifth_drv_fasync\n");return fasync_helper (fd, filp, on, &button_async);}static struct file_operations sencod_drv_fops = { .owner = THIS_MODULE, /* 這是一個宏，推向編譯模塊時自動創建的__this_module變量 */ .open = fifth_drv_open, .read = fifth_drv_read, .release = fifth_drv_close,.poll = fifth_drv_poll,.fasync = fifth_drv_fasync,};int major;static int fifth_drv_init(void){major = register_chrdev(0, "fifth_drv", &sencod_drv_fops);fifthdrv_class = class_create(THIS_MODULE, "fifth_drv");fifthdrv_class_dev = class_device_create(fifthdrv_class, NULL, MKDEV(major, 0), NULL, "buttons"); /* /dev/buttons */gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);gpfdat = gpfcon + 1;gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);gpgdat = gpgcon + 1;return 0;}static void fifth_drv_exit(void){unregister_chrdev(major, "fifth_drv");class_device_unregister(fifthdrv_class_dev);class_destroy(fifthdrv_class);iounmap(gpfcon);iounmap(gpgcon);return 0;}module_init(fifth_drv_init);module_exit(fifth_drv_exit);MODULE_LICENSE("GPL");

----------------------------------------------------------我-是漂亮的分割線------------------------------------------------------------------------------------------------------------------------------

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#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;void my_signal_fun(int signum) {unsigned char key_val;read(fd, &key_val, 1);printf("key_val: 0x%x\n", key_val); }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);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){sleep(1000);}return 0; }

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