[Linux内核驱动]应用

应用

更多详细内容可以查看我的github

设计一个FIFO的globalmem

代码

globalfifo.c

/*
 * @Date: 2024-05-12 10:19:14
 * @author: lidonghang-02 [email protected]
 * @LastEditTime: 2024-05-26 20:01:32
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/sched.h>

#include "globalfifo.h"

#define GLOBALFIFO_SIZE 0x10
#define GLOBALFIFO_MAJOR 0
#define GLOBALFIFO_MINOR 0
#define GLOBALFIFO_NR_DEVS 1

static int globalfifo_major = GLOBALFIFO_MAJOR;
static int globalfifo_minor = GLOBALFIFO_MINOR;
static int globalfifo_nr_devs = GLOBALFIFO_NR_DEVS;

static struct class *globalfifo_cls;
struct globalfifo_dev
{
 struct cdev cdev;
 struct device *class_dev;
 unsigned int len;
 unsigned char mem[GLOBALFIFO_SIZE];

 struct mutex mutex;
 wait_queue_head_t r_wq;
 wait_queue_head_t w_wq;
};

static struct globalfifo_dev *globalfifo_devp;

static int globalfifo_open_func(struct inode *inode, struct file *filp)
{
 struct globalfifo_dev *dev = container_of(inode->i_cdev, struct globalfifo_dev, cdev);
 filp->private_data = dev;
 printk(KERN_INFO "globalfifo_open\n");
 return 0;
}

static int globalfifo_release_func(struct inode *inode, struct file *filp)
{
 printk(KERN_INFO "globalfifo_release\n");
 return 0;
}

static ssize_t globalfifo_read_func(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{
 struct globalfifo_dev *dev = filp->private_data;
 int ret = 0;
 DECLARE_WAITQUEUE(wait, current);
 mutex_lock(&dev->mutex);
 add_wait_queue(&dev->r_wq, &wait);

 while (dev->len == 0)
 {
 if (filp->f_flags & O_NONBLOCK)
 {
 ret = -EAGAIN;
 goto out_1;
 }
 __set_current_state(TASK_INTERRUPTIBLE);
 mutex_unlock(&dev->mutex);

 schedule();
 if (signal_pending(current))
 {
 ret = -ERESTARTSYS;
 goto out_2;
 }
 mutex_lock(&dev->mutex);
 }

 if (count > dev->len)
 count = dev->len;

 if (copy_to_user(buf, dev->mem, count) != 0)
 ret = -EFAULT;
 else
 {
 dev->len = dev->len - count;
 memcpy(dev->mem, dev->mem + count, dev->len);
 ret = count;
 wake_up_interruptible(&dev->w_wq);
 }

out_1:
 mutex_unlock(&dev->mutex);
out_2:
 remove_wait_queue(&dev->r_wq, &wait);
 set_current_state(TASK_RUNNING);
 return ret;
}

static ssize_t globalfifo_write_func(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos)
{
 int ret = -ENOMEM;
 struct globalfifo_dev *dev = filp->private_data;
 DECLARE_WAITQUEUE(wait, current);

 mutex_lock(&dev->mutex);
 add_wait_queue(&dev->w_wq, &wait);

 while (dev->len == GLOBALFIFO_SIZE)
 {
 if (filp->f_flags & O_NONBLOCK)
 {
 ret = -EAGAIN;
 goto out_1;
 }

 __set_current_state(TASK_INTERRUPTIBLE);

 mutex_unlock(&dev->mutex);

 schedule();
 if (signal_pending(current))
 {
 ret = -ERESTARTSYS;
 goto out_2;
 }
 mutex_lock(&dev->mutex);
 }
 if (count > GLOBALFIFO_SIZE - dev->len)
 count = GLOBALFIFO_SIZE - dev->len;

 if (copy_from_user(dev->mem + dev->len, buf, count))
 ret = -EFAULT;
 else
 {
 dev->len += count;
 wake_up_interruptible(&dev->r_wq);
 ret = count;
 }
out_1:
 mutex_unlock(&dev->mutex);
out_2:
 remove_wait_queue(&dev->w_wq, &wait);
 set_current_state(TASK_RUNNING);
 return ret;
}

static long globalfifo_ioctl_func(struct file *filp, unsigned int cmd, unsigned long arg)
{
 struct globalfifo_dev *dev = filp->private_data;
 int ret = 0;

 // 检查幻数(返回值POSIX标准规定，也用-EINVAL)
 if (_IOC_TYPE(cmd) != GLOBALFIFO_MAGIC)
 return -ENOTTY;
 // 检查命令编号
 if (_IOC_NR(cmd) > GLOBALFIFO_MAXNR)
 return -ENOTTY;
 // 检查命令方向，并验证用户空间指针的访问权限。
 if (_IOC_DIR(cmd) & _IOC_READ)
 ret = !access_ok(VERIFY_WRITE, (void __user *)arg, _IOC_SIZE(cmd));
 else if (_IOC_DIR(cmd) & _IOC_WRITE)
 ret = !access_ok(VERIFY_READ, (void __user *)arg, _IOC_SIZE(cmd));

 if (ret)
 return -EFAULT;

 switch (cmd)
 {
 case GLOBALFIFO_CLEAR:
 mutex_lock(&dev->mutex);
 dev->len = 0;
 memset(dev->mem, 0, GLOBALFIFO_SIZE);
 mutex_unlock(&dev->mutex);
 break;
 default:
 return -EINVAL;
 }
 return 0;
}

static const struct file_operations globalfifo_fops =
 {
 .owner = THIS_MODULE,
 .read = globalfifo_read_func,
 .write = globalfifo_write_func,
 .unlocked_ioctl = globalfifo_ioctl_func,
 .open = globalfifo_open_func,
 .release = globalfifo_release_func,
};

static int __init globalfifo_init_module(void)
{
 int ret = 0, i;
 dev_t devno = MKDEV(globalfifo_major, globalfifo_minor);

 if (globalfifo_major)
 ret = register_chrdev_region(devno, globalfifo_nr_devs, "globalfifo");
 else
 {
 ret = alloc_chrdev_region(&devno, globalfifo_minor, globalfifo_nr_devs, "globalfifo");
 globalfifo_major = MAJOR(devno);
 }

 if (ret < 0)
 return ret;

 globalfifo_devp = kzalloc(sizeof(struct globalfifo_dev) * globalfifo_nr_devs, GFP_KERNEL);
 if (!globalfifo_devp)
 {
 printk(KERN_WARNING "alloc mem failed");
 ret = -ENOMEM;
 goto out_1;
 }

 globalfifo_cls = class_create(THIS_MODULE, "globalfifo");
 if (IS_ERR(globalfifo_cls))
 {
 printk(KERN_WARNING "Error creating class for ioctl");
 goto out_2;
 }

 for (i = 0; i < globalfifo_nr_devs; i++)
 {
 cdev_init(&globalfifo_devp[i].cdev, &globalfifo_fops);
 globalfifo_devp[i].cdev.owner = THIS_MODULE;
 ret = cdev_add(&globalfifo_devp[i].cdev, MKDEV(globalfifo_major, globalfifo_minor + i), 1);
 if (ret)
 printk(KERN_WARNING "Error adding cdev for device %d", i);
 else
 {
 globalfifo_devp[i].class_dev = device_create(globalfifo_cls, NULL, MKDEV(globalfifo_major, globalfifo_minor + i), NULL, "globalfifo%d", i);
 if (IS_ERR(globalfifo_devp[i].class_dev))
 printk(KERN_WARNING "Error creating device for device %d", i);
 }
 mutex_init(&globalfifo_devp[i].mutex);
 init_waitqueue_head(&globalfifo_devp[i].r_wq);
 init_waitqueue_head(&globalfifo_devp[i].w_wq);
 }
 return 0;
out_2:
 kfree(globalfifo_devp);
out_1:
 unregister_chrdev_region(devno, globalfifo_nr_devs);
 return ret;
}

static void __exit globalfifo_exit_module(void)
{
 int i;
 for (i = 0; i < globalfifo_nr_devs; i++)
 {
 device_destroy(globalfifo_cls, MKDEV(globalfifo_major, globalfifo_minor + i));
 cdev_del(&globalfifo_devp[i].cdev);
 }
 class_destroy(globalfifo_cls);
 kfree(globalfifo_devp);
 unregister_chrdev_region(MKDEV(globalfifo_major, globalfifo_minor), globalfifo_nr_devs);
 printk(KERN_INFO "globalfifo exit\n");
}

module_param(globalfifo_major, int, S_IRUGO);
module_param(globalfifo_minor, int, S_IRUGO);
module_param(globalfifo_nr_devs, int, S_IRUGO);

module_init(globalfifo_init_module);
module_exit(globalfifo_exit_module);

MODULE_AUTHOR("lidonghang-02");
MODULE_LICENSE("GPL");

globalfifo.h

#ifndef _GLOBALFIFO_H_
#define _GLOBALFIFO_H_

#define GLOBALFIFO_MAGIC 'c'

#define GLOBALFIFO_CLEAR _IO(GLOBALFIFO_MAGIC, 0)

#define GLOBALFIFO_MAXNR 0

#endif /* _GLOBALFIFO_H_ */