What is the function of the register_chrdev function in Linux?
The function register_chrdev in Linux is used to register a character device driver. Its prototype is as follows:
int register_chrdev(unsigned int major, const char *name, const struct file_operations *fops);
Explanation of parameters:
- Major: The major device number is used to uniquely identify a character device driver.
- name: The name of the driver.
- fops: A pointer to a file_operations structure, which defines the operations supported by the driver.
The main purpose of the register_chrdev function is to register a character device driver in the Linux kernel, informing the kernel of its existence and associating it with a major device number. This allows the kernel to properly handle requests from user programs accessing the device files through the file system.
After using the register_chrdev function, the kernel will assign a corresponding device number and associate it with the driver. Subsequently, user programs can open the device file and perform read and write operations on the device through system calls. The kernel will then pass these operations to the corresponding character device driver.
At the same time, the register_chrdev function also creates a character device class and device file node. This allows user programs to access the device through the device file node without having to worry about the specific device number.
It is important to note that the register_chrdev function needs to be called in the initialization function of a character device driver and can only be called once.
