87 lines
1.5 KiB
C
87 lines
1.5 KiB
C
#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/cdev.h>
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MODULE_LICENSE("GPL v2");
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static ssize_t demo_read(struct file *filp, char __user *buff, size_t size, loff_t *pos)
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{
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printk("%s %d\n", __func__, __LINE__);
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return size;
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}
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static ssize_t demo_write(struct file *filp, const char __user *buff, size_t size, loff_t *pos)
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{
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printk("%s %d\n", __func__, __LINE__);
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return size;
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}
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static int demo_open(struct inode *inode, struct file *filp)
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{
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printk("%s %d\n", __func__, __LINE__);
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return 0;
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}
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static int demo_release(struct inode *inode, struct file *filp)
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{
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printk("%s %d\n", __func__, __LINE__);
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return 0;
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}
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struct file_operations demo_fops = {
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.owner = THIS_MODULE,
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.read = demo_read,
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.write = demo_write,
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.open = demo_open,
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.release = demo_release,
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};
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static dev_t dev;
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static struct cdev *cdev;
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int demo_init(void)
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{
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int rc;
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rc = alloc_chrdev_region(&dev, 0, 1, "demo");
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if (rc) {
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printk("failed to alloc chrdev number\n");
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return rc;
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}
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cdev = cdev_alloc();
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if (!cdev) {
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printk("failed to alloc cdev\n");
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rc = -ENOMEM;
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goto out_unregister_chrdev;
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}
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cdev->owner = THIS_MODULE;
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cdev_init(cdev, &demo_fops);
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rc = cdev_add(cdev, dev, 1);
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if (rc) {
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printk("failed to add char device\n");
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goto out_free_cdev;
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}
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return 0;
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out_free_cdev:
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kobject_put(&cdev->kobj);
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out_unregister_chrdev:
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unregister_chrdev_region(dev, 1);
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return rc;
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}
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void demo_exit(void)
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{
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cdev_del(cdev);
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unregister_chrdev_region(dev, 1);
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}
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module_init(demo_init);
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module_exit(demo_exit);
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