linux驱动的异步通知(kill_fasync,fasync)---- 驱动程序向应用程序发送信号
Posted 苏博
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应用程序
- #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>
- /* fifthdrvtest
- */
- int fd;
- //信号处理函数
- 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;
- //在应用程序中捕捉SIGIO信号(由驱动程序发送)
- signal(SIGIO, my_signal_fun);
- fd = open("/dev/buttons", O_RDWR);
- if (fd < 0)
- {
- printf("can‘t open!\n");
- }
- //将当前进程PID设置为fd文件所对应驱动程序将要发送SIGIO,SIGUSR信号进程PID
- fcntl(fd, F_SETOWN, getpid());
- //获取fd的打开方式
- Oflags = fcntl(fd, F_GETFL);
- //将fd的打开方式设置为FASYNC --- 即 支持异步通知
- // 该行代码执行会触发 驱动程序中 file_operations->fasync 函数 ------fasync函数调用 fasync_helper初始化一个fasync_struct结构体,该结构体描述了将要发送信号的进程 PID (fasync_struct->fa_file->f_owner->pid)
- fcntl(fd, F_SETFL, Oflags | FASYNC);
- while (1)
- {
- sleep(1000);
- }
- return 0;
- }
驱动程序
- #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;
- static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
- /* 中断事件标志, 中断服务程序将它置1,fifth_drv_read将它清0 */
- static volatile int ev_press = 0;
- static struct fasync_struct *button_async;
- struct pin_desc{
- unsigned int pin;
- unsigned int key_val;
- };
- /* 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对应GPG0,GPG3,GPG5,GPG6
- */
- struct pin_desc pins_desc[4] = {
- {S3C2410_GPG0, 0x01},
- {S3C2410_GPG3, 0x02},
- {S3C2410_GPG5, 0x03},
- {S3C2410_GPG6, 0x04},
- };
- /*
- * 确定按键值
- */
- 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 */
- //发送信号SIGIO信号给fasync_struct 结构体所描述的PID,触发应用程序的SIGIO信号处理函数
- kill_fasync (&button_async, SIGIO, POLL_IN);
- return IRQ_RETVAL(IRQ_HANDLED);
- }
- static int fifth_drv_open(struct inode *inode, struct file *file)
- {
- /* 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 fifth_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
- {
- if (size != 1)
- return -EINVAL;
- /* 如果没有按键动作, 休眠 */
- wait_event_interruptible(button_waitq, ev_press);
- /* 如果有按键动作, 返回键值 */
- 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_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]);
- return 0;
- }
- static unsigned fifth_drv_poll(struct file *file, poll_table *wait)
- {
- unsigned int mask = 0;
- poll_wait(file, &button_waitq, wait); // 不会立即休眠
- 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");
- //初始化/释放 fasync_struct 结构体 (fasync_struct->fa_file->f_owner->pid)
- return fasync_helper (fd, filp, on, &button_async);
- }
- static struct file_operations sencod_drv_fops = {
- .owner = THIS_MODULE, /* 这是一个宏,推向编译模块时自动创建的__this_module变量 */
- .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;
- 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);
- return 0;
- }
- module_init(fifth_drv_init);
- module_exit(fifth_drv_exit);
- MODULE_LICENSE("GPL");
http://blog.csdn.net/psvoldemort/article/details/21184525
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