Linux设备驱动之异步通知
2017-07-16 21:02
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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");
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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