linux timer 驱动

timer driver 源码

#include "linux/device/class.h"
#include "linux/export.h"
#include "linux/uaccess.h"
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/timer.h>

#define MY_TIMER_NAME "my_timer" /* 设备名 */
#define MY_TIMER_NUM 1           /* 设备数目 */

static void kernel_timer_expires(struct timer_list *t);
static DEFINE_TIMER(test_timer2, kernel_timer_expires);

typedef struct {
    dev_t dev_id;                  /* 设备号 */
    struct cdev c_dev;             /* cdev */
    struct class *class;           /* 类 */
    struct device *device;         /* 设备 */
    int major;                     /* 主设备号 */
    int minor;                     /* 次设备号 */
    struct timer_list test_timer1; /* timer1 */
} new_chrdev_t;

static new_chrdev_t new_chrdev;

static void kernel_timer_expires(struct timer_list *t)
{
    if (t == &(new_chrdev.test_timer1)) {
        printk("Timer 1 is coming\r\n");
        mod_timer(&(new_chrdev.test_timer1),
                  jiffies + 1 * HZ); // 重新设置timer1 1s timeout
    } else if (t == &test_timer2) {
        printk("Timer 2 is coming\r\n");
        mod_timer(&test_timer2, jiffies + 2 * HZ); // 重新设置timer2 2s timeout
    } else {
        printk("Err: timer is unknown!!!\r\n");
    }
}

static int my_timer_open(struct inode *inode, struct file *file)
{
    printk("k: my_timer open\r\n");

    //初始化timer1
    timer_setup(&(new_chrdev.test_timer1), kernel_timer_expires, 0);

    //启动timer1、timer2
    mod_timer(&(new_chrdev.test_timer1), jiffies + 1 * HZ); // 1s timeout
    mod_timer(&(test_timer2), jiffies + 2 * HZ);            // 2s timeout

    return 0;
}

static int my_timer_release(struct inode *inode, struct file *file)
{
    printk("k: my_timer release\r\n");

    return 0;
}

static struct file_operations my_timer_fops = {
    .owner = THIS_MODULE,
    .open = my_timer_open,
    .release = my_timer_release,
};

static int __init my_timer_init(void)
{
    int err = 0;

    err = alloc_chrdev_region(&new_chrdev.dev_id, 0, MY_TIMER_NUM,
                              MY_TIMER_NAME);
    if (err < 0) {
        printk("k: alloc chrdev region failed err = %d\r\n", err);
        goto err_chrdev;
    }

    /* get major and minor */
    new_chrdev.major = MAJOR(new_chrdev.dev_id);
    new_chrdev.minor = MINOR(new_chrdev.dev_id);
    printk("k: newcheled major=%d,minor=%d\r\n", new_chrdev.major,
           new_chrdev.minor);

    new_chrdev.c_dev.owner = THIS_MODULE;
    cdev_init(&new_chrdev.c_dev, &my_timer_fops);
    err = cdev_add(&new_chrdev.c_dev, new_chrdev.dev_id, MY_TIMER_NUM);
    if (err < 0) {
        printk("k: cdev add failed err = %d\r\n", err);
        goto err_cdev_add;
    }

    new_chrdev.class = class_create(MY_TIMER_NAME);
    if (IS_ERR(new_chrdev.class)) {
        err = PTR_ERR(new_chrdev.class);
        goto err_class_create;
    }

    new_chrdev.device = device_create(new_chrdev.class, NULL, new_chrdev.dev_id,
                                      NULL, MY_TIMER_NAME);
    if (IS_ERR(new_chrdev.device)) {
        err = PTR_ERR(new_chrdev.device);
        goto err_device_create;
    }

    printk("k: base module init\r\n");

    return 0;

err_device_create:
    class_destroy(new_chrdev.class);
err_class_create:
    cdev_del(&new_chrdev.c_dev);
err_cdev_add:
    unregister_chrdev_region(new_chrdev.dev_id, MY_TIMER_NUM);
err_chrdev:
    return err;
}

static void __exit my_timer_exit(void)
{
    device_destroy(new_chrdev.class, new_chrdev.dev_id);
    class_destroy(new_chrdev.class);
    cdev_del(&new_chrdev.c_dev);
    unregister_chrdev_region(new_chrdev.dev_id, MY_TIMER_NUM);

    del_timer_sync(&(new_chrdev.test_timer1));
    del_timer_sync(&test_timer2);

    printk("k: base module exit!\r\n");
}

module_init(my_timer_init);
module_exit(my_timer_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("tyustli");
MODULE_INFO(intree, "Y"); /* loading out-of-tree module taints kernel */

timer app 源码

#include "stdio.h"
#include "unistd.h"
#include "sys/types.h"
#include "sys/stat.h"
#include "fcntl.h"
#include "stdlib.h"
#include "string.h"

int main(int argc, char *argv[])
{
    int fd, retvalue;
    char *filename;

    if (argc != 3) {
        printf("u: error Usage!\r\n");
        return -1;
    }

    filename = argv[1];

    /* 打开驱动文件 */
    fd = open(filename, O_RDWR);
    if (fd < 0) {
        printf("u: can't open file %s\r\n", filename);
        return -1;
    }

    /* 关闭设备 */
    retvalue = close(fd);
    if (retvalue < 0) {
        printf("u: can't close file %s\r\n", filename);
        return -1;
    }

    return 0;
}

编译

../my_module_build.sh ../0014_timer/

查看模块 ko 文件

ls /lib/modules/6.5.7+/
my_module.ko

设备模块安装

modprobe my_module
k: newcheled major=248,minor=0
k: base module init

查看设备

~ # ls /sys/class/
ata_device    graphics      mmc_host      rtc           vc
ata_link      hwmon         mtd           scsi_device   virtio-ports
ata_port      i2c-adapter   my_timer      scsi_disk     vtconsole
backlight     input         net           scsi_host     wakeup
bdi           leds          power_supply  sound
block         mdio_bus      pps           tty
devlink       mem           ptp           ubi
drm           misc          regulator     usbmon

应用程序

ls /lib/modules/6.5.7+/
my_app

使用 timer

lib/modules/6.5.7+/my_app /dev/my_timer 1

效果

Timer 1 is coming
Timer 1 is coming
Timer 2 is coming
Timer 1 is coming
Timer 1 is coming
Timer 2 is coming
Timer 1 is coming
Timer 1 is coming

退出

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