리눅스가 work queue를 다양하게 사용한다. 나는 초짜라 DECLARE_WORK와 INIT_WORK를 구분할 수 없었다. DECLARE_WORK가 work struct를 전역 변수로 선언한다. 여러 work로 같은 데이터에 접근할 수 있다. workqueue funtion() 파라미터로 work struct를 넣는데, 여기로 work를 전달하면 된다. 코드가 넝마조각이 되고 있다.
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/gpio.h> //GPIO
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/fcntl.h>
#include <linux/workqueue.h>
#define GPIO_10_OUT (10)
#define DEVICE_DATA_MAX 256
unsigned int GPIO_irqNumber;
/*\uc0ac\uc6a9\uc790 \ub370\uc774\ud130 \ubd80\ubd84*/
static struct my_device_data{
struct cdev cdev;
int index;
char my_string[DEVICE_DATA_MAX];
struct work_struct mywork;
struct work_struct work_read;
} my_data_global;
struct my_device_data *work_ptr;
struct my_device_data *work_ptr_read;
struct my_device_data *my_data;
/*workque initiate*/
void workqueue_fn(struct work_struct *work);
//defien workqueue_fn//
void workqueue_fn(struct work_struct *work_ptr)
{
/*work_ptr\ub85c \uc0ac\uc6a9\uc790 \uc815\uc758 \ub370\uc774\ud130 \uc811\uadfc*/
struct my_device_data *my_pointer;
//container of \ub85c \uc0ac\uc6a9\uc790 \ub370\uc774\ud130 \uc811\uadfc.
my_pointer = container_of(work_ptr, struct my_device_data, mywork);
my_pointer->index++;
pr_info("Executing workqueue function\n");
pr_info("index is %d\n",my_pointer->index);
}
void workqueue_read(struct work_struct *work_ptr)
{
/*work_ptr\ub85c \uc0ac\uc6a9\uc790 \uc815\uc758 \ub370\uc774\ud130 \uc811\uadfc*/
struct my_device_data *my_pointer;
//container of \ub85c \uc0ac\uc6a9\uc790 \ub370\uc774\ud130 \uc811\uadfc.
my_pointer = container_of(work_ptr, struct my_device_data, work_read);
my_pointer->index++;
pr_info("opened, index is %d\n", my_pointer->index);
}
static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
{
/*Scheduling work queue*/
schedule_work(&work_ptr->mywork);
pr_info("workqueue scheduled \n");
return IRQ_HANDLED;
}
//device driver \uc791\uc131 \ubd80\ubd84.
/*************\ub4dc\ub77c\uc774\ubc84 \ud568\uc218 ******************/
static int mydriver_open(struct inode *inode, struct file *file);
static int mydriver_release(struct inode *inode, struct file *file);
static ssize_t mydriver_read(struct file *flip,
char *buf, size_t len, loff_t *off);
static ssize_t mydriver_write(struct file *flip,
const char *buf, size_t len, loff_t *off);
/********************************************/
//file operation structure
static struct file_operations fops =
{
.owner = THIS_MODULE,
.read = mydriver_read,
.write = mydriver_write,
.open = mydriver_open,
.release = mydriver_release,
};
static int mydriver_open(struct inode *inode, struct file *file)
{
pr_info("Deviced file was opend.\n");
//my_data_global.index++;
return 0;
}
static int mydriver_release(struct inode *inode, struct file *file)
{
pr_info("Deviced file was closed.\n");
return 0;
}
static int mydriver_read(struct file *file,
char *buf, size_t len, loff_t *off)
{
struct my_device_data *my_data;
size_t datalen, read_len;
my_data = (struct my_device_data*)&my_data_global;
datalen = strlen(my_data->my_string);
//\ucd5c\ub300\uac12\uc73c\ub85c \uac15\uc81c \uc124\uc815
if(len > datalen)
{
len = datalen;
}
read_len = len - *off;
if (read_len <= 0)
return 0;
pr_info("start %p, offset is %lld, read_len is %d\n", my_data->my_string, *off, read_len);
if(copy_to_user(buf, my_data->my_string+*off, read_len))
return -EFAULT;
//read_len = datalen-*off;
*off += read_len;
pr_info("kernel has %d, read %d characters from kernel\n", datalen, read_len);
//zero\ub97c \ubc18\ud658\ud560 \ub54c\uae4c\uc9c0 \ubc18\ubcf5.
schedule_work(&work_ptr->work_read);
return read_len;
}
static int mydriver_write(struct file *flip,
const char *buf, size_t len, loff_t *off)
{
size_t datalen, write_len, start_pos;
my_data = &my_data_global;
start_pos = strlen(my_data->my_string);
datalen = strlen(my_data->my_string);
if(len > datalen)
{
len = DEVICE_DATA_MAX;
}
write_len = len - *off;
if(copy_from_user(my_data->my_string + start_pos + *off, buf, write_len))
return -EFAULT;
*off += write_len;
return write_len;
}
dev_t dev = 0;
static struct cdev my_cdev;
static struct class *dev_class;
static int __init init_hw(void)
{
//\ub514\ubc14\uc774\uc2a4 \ub4f1\ub85d
if(( alloc_chrdev_region(&dev, 0, 1, "test_device") < 0))
{
pr_err("[!]character device was not allocated\n");
goto r_unreg;
}
pr_info("[=]%d-%d, was allocated\n", MAJOR(dev), MINOR(dev));
//\ucd08\uae30\ud654
cdev_init(&my_cdev, &fops);
pr_info("[=]driver was initialized\n");
//\uc2dc\uc2a4\ud15c\uc5d0 \ucd94\uac00
if((cdev_add(&my_cdev, dev, 1)) < 0)
{
pr_err("[!]cannot add device to kernel\n");
goto r_del;
}
//class \ub9cc\ub4e6.
if((dev_class=class_create(THIS_MODULE, "my_class")) == NULL)
{
pr_err("[!]cannot add class\n");
goto r_class;
}
if((device_create(dev_class, NULL, dev, NULL, "my_device")) == NULL)
{
pr_err("[!]cannot create device\n");
goto r_device;
}
work_ptr = kmalloc(sizeof(*work_ptr), GFP_KERNEL);
if(work_ptr == NULL)
{
pr_err("[!]cannot allocate memory\n");
goto r_work;
}
INIT_WORK(&work_ptr->mywork, workqueue_fn);
//work_ptr_read = kmalloc(sizeof(*work_ptr), GFP_KERNEL);
INIT_WORK(&work_ptr->work_read, workqueue_read);
//gpio 10\ubc88\uc744 \uc0ac\uc6a9.
//export\ud558\uc5ec \uac04\ub2e8\ud788 \uc0ac\uc6a9.
//\uc785\ub825\uc740 \uac12\uc744 \uc368 \ub123\uc744 \uc218 \uc5c6\uc74c. \ucd9c\ub825\uc73c\ub85c \uc124\uc815.
GPIO_irqNumber = gpio_to_irq(GPIO_10_OUT);
pr_info("[=]irq %d was assinged\n",GPIO_irqNumber);
//interrupt \ub4f1\ub85d \ud544\uc694
if (request_irq(GPIO_irqNumber,
(void*)gpio_irq_handler,
IRQF_TRIGGER_RISING,
"my_device",
NULL))
{
pr_err("[!]my_device: cannot register IRQ\n");
goto r_gpio;
}
pr_info("[=]module was installed\n");
return 0;
r_gpio:
gpio_free(GPIO_10_OUT);
r_device:
device_destroy(dev_class,dev);
r_class:
class_destroy(dev_class);
r_del:
cdev_del(&my_cdev);
r_unreg:
unregister_chrdev_region(dev,1);
r_work:
kfree(work_ptr);
return -1;
}
static void __exit exit_hw(void) {
free_irq(GPIO_irqNumber, NULL);
gpio_free(GPIO_10_OUT);
//flush_work(struct work_struct *work);
device_destroy(dev_class,dev);
//class_unregister(dev_class);
class_destroy(dev_class);
cdev_del(&my_cdev);
unregister_chrdev_region(dev,1);
flush_work(&work_ptr->mywork);
kfree(work_ptr);
printk(KERN_INFO "module was removed\n");
}
module_init(init_hw);
module_exit(exit_hw);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("noname");
MODULE_DESCRIPTION("Hello, world!");
모듈을 로딩하고 인터럽트를 만들면 schedule_work로 등록한 workqueue_fn을 실행한다.
[ 52.456926] [=]236-0, was allocated [ 52.456935] [=]driver was initialized [ 52.457621] [=]irq 54 was assinged [ 52.457693] [=]module was installed [ 68.542830] workqueue scheduled [ 68.542855] Executing workqueue function [ 68.542866] index is 1 [ 69.549436] workqueue scheduled [ 69.549460] Executing workqueue function [ 69.549466] index is 2 [ 70.552638] workqueue scheduled [ 70.552659] Executing workqueue function [ 70.552663] index is 3
파일을 오픈하면 같은 데이터를 다른 work로 index를 접근할 수 있다. schedule_work(&work_ptr->work_read)를 디바이스를 읽을 때마다 실행한다.
[ 86.495196] Deviced file was opend. [ 86.495242] Deviced file was closed. [ 91.476276] Deviced file was opend. [ 91.476318] start 9f3ac859, offset is 0, read_len is 5 [ 91.476327] kernel has 5, read 5 characters from kernel [ 91.476367] opened, index is 4 [ 91.476430] Deviced file was closed. [ 105.664089] Deviced file was opend. [ 105.664138] start 9f3ac859, offset is 0, read_len is 5 [ 105.664149] kernel has 5, read 5 characters from kernel [ 105.664197] opened, index is 5 [ 105.664275] Deviced file was closed.
https://www.programmersought.com/article/61671813037/
https://stackoverflow.com/questions/7937245/how-to-use-linux-work-queue/7938990
https://github.com/fervagar/kernel_modules/blob/master/workQueue.c