标签：程序 状态 通过 描述符 s3c2440 配置 inter 结构体 按键驱动
目录
title: 字符设备驱动(七)按键异步通知
tags: linux
date: 2018-11-24 16:39:47
toc: true
---
以前使用kill -9 pid实际也就是发送信号给进程，信号9为关闭进程.我们使用 man signal查看需要头文件 #include <signal.h>测试程序如下如果用在gcc下编译需要为sleep函数添加头文件#include <unistd.h>
NAME
signal - ANSI C signal handling
SYNOPSIS
#include <signal.h>
typedef void (*sighandler_t)(int);
sighandler_t signal(int signum, sighandler_t handler);
实例函数如下arm-linux-gcc -o test test.c
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
//typedef void (*sighandler_t)(int);
void my_signal_fun(int signum)
{
static int cnt=0;
printf("signum=%d ,%d times\n",signum,++cnt );
}
int main(int argc, char const *argv[])
{
signal(SIGUSR1,my_signal_fun);
while(1)
{
sleep(100);
}
return 0;
}测试使用kill -USR1 pid后会打印信号
book@100ask:~/stu/dri/code/10th$ ./test &
[3] 4356
book@100ask:~/stu/dri/code/10th$ kill -USR1 4356
signum=10 ,1 times
book@100ask:~/stu/dri/code/10th$ kill -10 4356
signum=10 ,2 times驱动程序使用信号通知应用程序去读取按键
void kill_fasync(struct fasync_struct **fp, int sig, int band)发信号搜索下发送信号的函数kill_fasync，寻找一个字符设备是怎么使用的，在drivers/char/rtc.c中有如下调用
kill_fasync (&rtc_async_queue, SIGIO, POLL_IN);
//结构体定义如下:
static struct fasync_struct *rtc_async_queue;
struct fasync_struct {
int magic;
int fa_fd;
struct fasync_struct *fa_next; /* singly linked list */
struct file *fa_file;
};信号的接受者被定义在fasync_struct中，搜索下其初始化函数，发现函数rtc_fasync被调用如下形式，也就是类似于open、close的形式了
static const struct file_operations rtc_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.read = rtc_read,
#ifdef RTC_IRQ
.poll = rtc_poll,
#endif
.ioctl = rtc_ioctl,
.open = rtc_open,
.release = rtc_release,
.fasync = rtc_fasync,
};函数的原型如下，这个函数用来初始化结构体，应用程序会最终调用他告知驱动应该信号给哪个pid
static int rtc_fasync (int fd, struct file *filp, int on)
{
return fasync_helper (fd, filp, on, &rtc_async_queue);
}也就是是说应用程序通过fasync来调用驱动具体的rtc_fasync，这个函数会设置fasync_struct这个结构体，这个结构体会被当做驱动发送信号函数的参数，也就是说应用程序告诉驱动程序其目标
步骤如下
定义一个fasync_struct结构体，在中断中使用发送信号
定义一个供app函数调用的.fasync
static int drv_fasync (int fd, struct file *filp, int on)
{
printk("driver: drv_fasync\n");
return fasync_helper (fd, filp, on, &drv_async_queue);
}设置哪个进程将接受到来自fd的SIGIO信号，如何获取自身程序的pid
man pid
SYNOPSIS
#include <sys/types.h>
#include <unistd.h>
pid_t getpid(void);
pid_t getppid(void);获取当前的标志，添加FASYNC机制
? 复制一个现存的描述符(cmd=F_DUPFD) 。
? 获得/设置文件描述符标记(cmd=F_GETFD或F_SETFD) 。
? 获得/设置文件状态标志(cmd=F_GETFL或F_SETFL) 。
? 获得/设置异步I/O有权(cmd=F_GETOWN或F_SETOWN) 。
? 获得/设置记录锁(cmd=F_GETLK,F_SETLK或F_SETLKW)。程序
fcntl(fd, F_SETOWN, getpid()); //告知信号发送给哪个进程，
Oflags = fcntl(fd, F_GETFL); //获取当前的文件状态
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
//这个会触发驱动函数的fasync驱动
#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>
//#include <linux/interrupt.h>
volatile unsigned long *gpfcon;
volatile unsigned long *gpfdat;
volatile unsigned long *gpgcon;
volatile unsigned long *gpgdat;
static struct class *drv_class;
static struct class_device *drv_class_dev;
// 定义一个名为`button_waitq`的队列
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
// flag=1 means irq happened and need to update
int flag=0;
static struct fasync_struct *drv_async_queue;
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_GPF0, 0x01},
{S3C2410_GPF2, 0x02},
{S3C2410_GPG3, 0x03},
{S3C2410_GPG11, 0x04},
};
static irqreturn_t buttons_irq(int irq, void *dev_id)
{
printk("irq%d\r\n",irq);
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;
}
//wake_up_interruptible(&button_waitq); /* 唤醒休眠的进程 */
flag=1;
kill_fasync (&drv_async_queue, SIGIO, POLL_IN);
return IRQ_RETVAL(IRQ_HANDLED);
}
static unsigned 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 (flag)
mask |= POLLIN | POLLRDNORM;
return mask;
}
static int 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, 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;
}
int 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 ssize_t drv_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
//int minor = MINOR(file->f_dentry->d_inode->i_rdev);
//printk("drv_write=%d\n",minor);
return 0;
}
static ssize_t 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, flag);
/* 如果有按键动作, 返回键值 */
copy_to_user(buf, &key_val, 1);
flag = 0;
return 1;
}
static int drv_fasync (int fd, struct file *filp, int on)
{
printk("driver: drv_fasync\n");
return fasync_helper (fd, filp, on, &drv_async_queue);
}
static struct file_operations 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 = drv_open,
.write = drv_write,
.read = drv_read,
.release = drv_close,
.poll = drv_poll,
.fasync = drv_fasync,
};
static int major;
static int drv_init(void)
{
int minor=0;
major=register_chrdev(0, "drv", &drv_fops); // 注册, 告诉内核
drv_class = class_create(THIS_MODULE, "drv");
drv_class_dev = class_device_create(drv_class, NULL, MKDEV(major, 0), NULL, "xyz%d", minor);
gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
gpfdat = gpfcon + 1;
gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);
gpgdat = gpgcon + 1;
return 0;
}
static void drv_exit(void)
{
unregister_chrdev(major, "drv"); // 卸载
class_device_unregister(drv_class_dev);
class_destroy(drv_class);
iounmap(gpfcon);
iounmap(gpgcon);
}
module_init(drv_init);
module_exit(drv_exit);
MODULE_AUTHOR("xxx");
MODULE_VERSION("0.1.0");
MODULE_DESCRIPTION("S3C2410/S3C2440 LED Driver");
MODULE_LICENSE("GPL");
App
#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>
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/xyz0", O_RDWR);
if (fd < 0)
{
printf("can‘t open!\n");
}
fcntl(fd, F_SETOWN, getpid());
Oflags = fcntl(fd, F_GETFL);
fcntl(fd, F_SETFL, Oflags | FASYNC);
while (1)
{
sleep(1000);
}
return 0;
}可以发现打开文件的时候会有提示driver: drv_fasync，说明App会主动调用.fasync
# insmod dri.ko
# 后台运行
# ./test &
# driver: drv_fasync
#实际休眠状态的
# ps
PID Uid VSZ Stat Command
798 0 1308 S ./test
....
# 按键按下正常打印
# irq55
key_val: 0x3
irq55
key_val: 0x83
irq18标签：程序 状态 通过 描述符 s3c2440 配置 inter 结构体 按键驱动
原文地址：https://www.cnblogs.com/zongzi10010/p/10016369.html
