Linux设备驱动之异步通知

来源：互联网发布：win7系统网络共享设置编辑：程序博客网时间：2024/05/17 04:23

作用：有按键按下，驱动程序提醒应用程序

如何实现？？？

①、应用程序：注册信号处理函数

②、谁发送信号？答：驱动

③、谁接收信号？答：应用程序，而且应用程序最关键的就是要告诉驱动应用程序的PID

④、怎么发？答：通过函数kill_fasync

为了使设备支持异步通知机制，驱动程序中涉及以下3项工作：

1. 支持F_SETOWN命令，能在这个控制命令处理中设置filp->f_owner为对应进程ID。

不过此项工作已由内核完成，设备驱动无须处理。

2. 支持F_SETFL命令的处理，每当FASYNC标志改变时，驱动程序中的fasync()函数将得以执行。

驱动中应该实现fasync()函数。

3. 在设备资源可获得时，调用kill_fasync()函数激发相应的信号

应用程序：

fcntl(fd, F_SETOWN, getpid()); // 告诉内核，发给谁

Oflags = fcntl(fd, F_GETFL);

fcntl(fd, F_SETFL, Oflags | FASYNC); // 改变fasync标记，最终会调用到驱动的faync > fasync_helper：初始化/释放fasync_struct

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;

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;

    /*Garmen : SIGIO信号安装my_signal_fun()作为处理函数，若信号SIGIO被捕获到，将执行my_signal_fun这个函数*/
    signal(SIGIO, my_signal_fun);

    fd = open("/dev/buttons", O_RDWR);
    if (fd < 0)
    {
        printf("can't open!\n");
    }
    /*Garmen : F_SETOWN IO控制命令设置设备文件的拥有者为本进程，这样从设备驱动发出的信号才能被本进程接收到*/
    fcntl(fd, F_SETOWN, getpid());

    Oflags = fcntl(fd, F_GETFL);

    /*Garmen : 通过F_SETFL IO控制命令设置设备文件以支持FASYNC， 即是异步通知模式
     *         改变fasync标记，最终会调用到驱动的faync > fasync_helper：初始化/释放 fasync_struct
     */
    fcntl(fd, F_SETFL, Oflags | FASYNC);


    while (1)
    {
        sleep(1000);
    }

    return 0;
}

驱动程序：

#include <linux/module.h>

#include <linux/sched.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/device.h>

#include <mach/gpio.h>

#include <linux/interrupt.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;

struct pin_desc pins_desc[4] = {

{S3C2410_GPF(0), 0x01},

{S3C2410_GPF(2), 0x02},

{S3C2410_GPG(3), 0x03},

{S3C2410_GPG(11), 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 */

/*Garmen : 在资源可获得的时候，调用kill_fasync()函数激发相应的信号*/

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为输入引脚 */

/* 配置GPG3,11为输入引脚 */

request_irq(IRQ_EINT0, buttons_irq, (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING), "S2", &pins_desc[0]);

request_irq(IRQ_EINT2, buttons_irq, (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING), "S3", &pins_desc[1]);

request_irq(IRQ_EINT11, buttons_irq, (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING), "S4", &pins_desc[2]);

request_irq(IRQ_EINT19, buttons_irq, (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING), "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_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]);

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");

/*Garmen :主要是这个函数可以获取得到用户空间的ID

*这个函数的作用是：处理FASYNC标志变更函数

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 = 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");

device_destroy(fifthdrv_class, MKDEV(major, 0));

class_destroy(fifthdrv_class);

iounmap(gpfcon);

iounmap(gpgcon);

return 0;

}

module_init(fifth_drv_init);

module_exit(fifth_drv_exit);

MODULE_LICENSE("GPL");

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