Linux内核中断底半部处理--工作队列

工作队列的使用过程：

工作队列相关函数介绍：

#include <workqueue.h> /*头文件包含*/

1.工作队列的创建及销毁：

定义一个工作队列结构体指针

static struct workqueue_struct *key_workqueue;

创建工作队列

struct workqueue_struct *create_workqueue(char *);

参数:工作队列的名称（字符串）

返回值:创建好的工作队列

销毁工作队列，参数为待销毁的工作队列

void destroy_workqueue(struct workqueue_struct *);

2.工作的创建、初始化

创建一个不带延时的工作（加入队列立即执行）

struct work_struct work;

工作初始化宏

INIT_WORK(&work, func);

参数1：用户已定义的work_struct变量（工作）

参数2：任务处理函数，用户实现（中断底半部）

3.添加工作到工作队列

int queue_work(struct workqueue_struct*wq,struct work_struct *work);

参数1：第1部创建的工作队列

参数2：第2部创建的工作

4.延迟工作的创建、初始化及添加：

定义一个带延时的工作

struct delayed_work dwork；

初始化带延迟的工作

INIT_DELAYED_WORK(&dwork, func);

添加带延迟的工作到工作队列

int queue_delayed_work(struct workqueue_struct *wq,

struct delayed_work *dwork, unsigned long delay);

参数delay：延迟时间（时钟滴答数)

【注】对于我们的开发板，一个时钟滴答=5ms

终止队列中的工作（即使处理程序已经在处理该任务）

int cancel_work_sync(struct work_struct *work);

int cancel_delayed_work_sync(struct delayed_work *dwork);

判断任务项目是否在进行中

int work_pending(struct work_struct work );

int delayed_work_pending(structdelayed_work work );

/*返回值为真表示正在运行，假表示停止*/

总结：

实例代码：

驱动端：

#include <linux/device.h>
#include <linux/interrupt.h>
#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 <mach/gpio.h>
#include <mach/regs-gpio.h>  		/*S5PV210_GPH3_BASE*/

#include <linux/workqueue.h>

#define EINT_DEVICE_ID			1

#define DRIVER_NAME				"key1_eint"
#define err(msg) 				printk(KERN_ERR "%s: " msg "\n", DRIVER_NAME)
#define __debug(fmt, arg...)	printk(KERN_DEBUG fmt, ##arg)

#define GPH0_CONREG			(S5PV210_GPH0_BASE + 0x00)
#define GPH0_DATREG			(S5PV210_GPH0_BASE + 0x04)
#define GPH0_UPREG			(S5PV210_GPH0_BASE + 0x08)
#define GPH0_DRVREG			(S5PV210_GPH0_BASE + 0x0c)

#define GPH3CON					(unsigned long)(S5PV210_GPH3_BASE+ 0x00)
#define GPH3DAT					(unsigned long)(S5PV210_GPH3_BASE + 0x04)
#define GPH2UP					(unsigned long)(S5PV210_GPH2_BASE + 0x08)

static int major = 0;		/* Driver Major Number */
static int minor = 0;		/* Driver Minor Number */
struct class *key_class;
static struct device *key_device;

static unsigned char key;

/* 定义工作队列指针变量，并定义工作变量。
* 在此例中我们采用自定义的方式(我们还可以
* 使用内核提供的工作队列,请参考ppt)
*/
static struct workqueue_struct *key_workqueue;
//static struct work_struct key_work;
static struct delayed_work key_work;
static struct work_struct key_work1;

/* 工作处理函数work_handler
* 该函数完成点亮/熄灭led灯的功能
*/
static void work_handler(struct work_struct *work)
{
unsigned long reg_data;

reg_data = readl(GPH0_DATREG);
reg_data ^= 0x01<<3;
writel(reg_data, GPH0_DATREG);

}
static void work_handler1(struct work_struct *work)
{
printk("haha you done\n");

}

irqreturn_t buttons_interrupt(int irq, void *dev_id)
{
key = (unsigned int)dev_id;
//__debug("in eint function...\n");

/*将work添加到工作队列workqueue中*/
//queue_work(key_workqueue, &key_work);
queue_delayed_work(key_workqueue,&key_work,1000);
queue_work(key_workqueue, &key_work1);
return IRQ_HANDLED;
}

/* the initialization of IO ports
* @prepare for key device and led device
*/
static void led_io_port_init(void)
{
unsigned long con_val, up_val;

con_val = readl(GPH0_CONREG);
con_val &= ~(0x0f<<12);
con_val |= (0x01<<12);
writel(con_val, GPH0_CONREG);

up_val = readl(GPH0_UPREG);
up_val &= ~(0X03<<6);
up_val |= (0X02<<6);
writel(up_val, GPH0_UPREG);
}

static void key_io_port_init(void)
{
unsigned long reg_val;

reg_val = readl(GPH3CON);
reg_val &= ~((0x0f<<0) | (0x0f<<4));
reg_val |= ((0x01<<0) | (0x01<<4));
writel(reg_val, GPH3CON);

reg_val = readl(GPH3DAT);
reg_val &= ~((0x01<<0) | (0x01<<1));
writel(reg_val, GPH3DAT);

reg_val = readl(GPH2UP);
reg_val &= ~(0x03<<8);
reg_val |= 0x02<<8;
writel(reg_val, GPH2UP);
}

static ssize_t key_read(struct file *filp, char *buf, size_t count, loff_t *f_pos)
{
int key_num;
int cpy_len;
int retval;

key_num = key;		//读取键值
key = 0;				//清除键值

cpy_len = min(sizeof(key_num), count);
retval = copy_to_user(buf, &key_num, cpy_len);

return (cpy_len - retval);
}

static struct file_operations key_fops = {
.owner = THIS_MODULE,
.read = key_read,
};

static int __init key_eint_init(void)
{
int retval;

key_io_port_init();
led_io_port_init();

/* 创建工作队列--workqueue*/
key_workqueue = create_workqueue("key_workqueue");
if(IS_ERR(key_workqueue)){
err("ceate workqueue failed!");
return PTR_ERR(key_workqueue);
}
/*初始化工作--work, 指定处理函数work_handler*/
//INIT_WORK(&key_work, work_handler);
INIT_DELAYED_WORK(&key_work,work_handler);
INIT_WORK(&key_work1, work_handler1);

retval = set_irq_type(IRQ_EINT(20),IRQ_TYPE_EDGE_FALLING);
if(retval){
err("IRQ_EINT20 set irq type failed");
goto error;
}

retval = request_irq(IRQ_EINT(20), buttons_interrupt, IRQF_DISABLED,
"KEY1", (void *)EINT_DEVICE_ID);
if(retval){
err("request eint20 failed");
goto error;
}

/* Driver register */
major = register_chrdev(major, DRIVER_NAME, &key_fops);
if(major < 0){
err("register char device fail");
retval = major;
goto error_register;
}
key_class=class_create(THIS_MODULE,DRIVER_NAME);
if(IS_ERR(key_class)){
err("class create failed!");
retval =  PTR_ERR(key_class);
goto error_class;
}
key_device=device_create(key_class,NULL, MKDEV(major, minor), NULL,DRIVER_NAME);
if(IS_ERR(key_device)){
err("device create failed!");
retval = PTR_ERR(key_device);
goto error_device;
}
__debug("register myDriver OK! Major = %d\n", major);
return 0;

error_device:
class_destroy(key_class);
error_class:
unregister_chrdev(major, DRIVER_NAME);
error_register:
free_irq(IRQ_EINT(20), (void *)EINT_DEVICE_ID);
error:
return retval;
}

static void __exit key_eint_exit(void)
{
/*清空工作队列*/
flush_workqueue(key_workqueue);
/*释放创建的工作队列，资源回收*/
destroy_workqueue(key_workqueue);

free_irq(IRQ_EINT(20), (void *)EINT_DEVICE_ID);

unregister_chrdev(major, DRIVER_NAME);
device_destroy(key_class,MKDEV(major, minor));
class_destroy(key_class);

return;
}

module_init(key_eint_init);
module_exit(key_eint_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Eric");

应用层：

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>

int main()
{
char *devname = "/dev/key1_eint";
int fd;
unsigned char key;

fd = open(devname, O_RDWR);
while(1)
{
read(fd, &key, sizeof(key));
if(key)
printf("the key = %d\n",key);
usleep(100*1000);
}
close(fd);
}