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_ID1#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);}