113 lines
2.3 KiB
C
Executable File
113 lines
2.3 KiB
C
Executable File
#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/cdev.h>
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#include <linux/kfifo.h>
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#define VSER_MAJOR 256
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#define VSER_MINOR 0
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#define VSER_DEV_CNT 2
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#define VSER_DEV_NAME "vser"
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static DEFINE_KFIFO(vsfifo0, char, 32);
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static DEFINE_KFIFO(vsfifo1, char, 32);
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struct vser_dev {
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struct kfifo *fifo;
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struct cdev cdev;
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};
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static struct vser_dev vsdev[2];
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static int vser_open(struct inode *inode, struct file *filp)
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{
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filp->private_data = container_of(inode->i_cdev, struct vser_dev, cdev);
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return 0;
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}
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static int vser_release(struct inode *inode, struct file *filp)
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{
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return 0;
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}
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static ssize_t vser_read(struct file *filp, char __user *buf, size_t count, loff_t *pos)
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{
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unsigned int copied = 0;
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struct vser_dev *dev = filp->private_data;
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kfifo_to_user(dev->fifo, buf, count, &copied);
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return copied;
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}
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static ssize_t vser_write(struct file *filp, const char __user *buf, size_t count, loff_t *pos)
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{
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unsigned int copied = 0;
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struct vser_dev *dev = filp->private_data;
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kfifo_from_user(dev->fifo, buf, count, &copied);
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return copied;
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}
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static struct file_operations vser_ops = {
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.owner = THIS_MODULE,
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.open = vser_open,
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.release = vser_release,
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.read = vser_read,
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.write = vser_write,
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};
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static int __init vser_init(void)
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{
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int i;
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int ret;
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dev_t dev;
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dev = MKDEV(VSER_MAJOR, VSER_MINOR);
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ret = register_chrdev_region(dev, VSER_DEV_CNT, VSER_DEV_NAME);
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if (ret)
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goto reg_err;
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for (i = 0; i < VSER_DEV_CNT; i++) {
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cdev_init(&vsdev[i].cdev, &vser_ops);
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vsdev[i].cdev.owner = THIS_MODULE;
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vsdev[i].fifo = i == 0 ? (struct kfifo *) &vsfifo0 : (struct kfifo*)&vsfifo1;
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ret = cdev_add(&vsdev[i].cdev, dev + i, 1);
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if (ret)
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goto add_err;
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}
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return 0;
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add_err:
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for (--i; i > 0; --i)
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cdev_del(&vsdev[i].cdev);
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unregister_chrdev_region(dev, VSER_DEV_CNT);
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reg_err:
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return ret;
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}
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static void __exit vser_exit(void)
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{
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int i;
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dev_t dev;
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dev = MKDEV(VSER_MAJOR, VSER_MINOR);
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for (i = 0; i < VSER_DEV_CNT; i++)
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cdev_del(&vsdev[i].cdev);
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unregister_chrdev_region(dev, VSER_DEV_CNT);
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}
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module_init(vser_init);
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module_exit(vser_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Kevin Jiang <jiangxg@farsight.com.cn>");
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MODULE_DESCRIPTION("A simple character device driver");
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MODULE_ALIAS("virtual-serial");
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