Character Device Drivers in deep

📚 Linux Kernel Programming - Character Device Drivers

🎉 Updated on Oct 10: We've added a new Downloads section to enhance your learning experience!

🚀 What will you learn from this course? This comprehensive course is designed to take you through the intricacies of character device drivers in the Linux kernel. You'll gain hands-on experience with the following key concepts:

• Introduction to Character Device Drivers: Get a foundational understanding of what character device drivers are and their role within the Linux kernel.

• Device Number and File: Learn about device numbers and how they relate to device files, and understand the importance of these in interacting with devices.

• Allocating Device Numbers: Statically and dynamically allocate device numbers for your drivers, ensuring that your devices can be uniquely identified by the kernel.

• Creating Device Files: Discover how to manually create device files using mknod or automatically with udev, and why it's crucial for device accessibility.

• Registering Characters Devices: Register your character devices and their corresponding file operations with the Linux kernel, making them accessible by user space applications.

• Copying Data: Learn how to safely copy data between user space and kernel space, ensuring the integrity and security of the data transfer.

• File Operations: Understand the structures like struct file and struct inode, and implement the required file operations (open, release, read, write, llseek, ioctl).

• Multiple Device Nodes and Private Data: Create multiple device nodes and add support for private data within your driver.

• Flow of Write System Call: Trace the flow of a write system call from its entry point in the kernel to your driver's write file operation.

• Error Cases in ioctl: Learn how to handle all possible error cases in your ioctl implementation, making your driver more robust and reliable.

• Signals from Kernel to User Space: Send signals from kernel space to user space applications, facilitating communication between the two spaces.

• Access Control and Capabilities: Explore various access control mechanisms and capabilities within the Linux kernel to ensure secure device operation.

• Misc Driver: Dive into using the MiscDriver for simpler character devices that do not fit into other drivers like char or block drivers.

🛠️ API's covered in this course: This course covers a range of APIs essential for working with character device drivers, including:

• MAJOR and MINOR numbers
• MKDEV function
• Device registration with register_chrdev_region
• Dynamic device number allocation with alloc_chrdev_region
• Creating and managing classes and devices with class_create, device_create, etc.
• Kernel functions for user data exchange like copy_from_user, copy_to_user, put_user, get_user
• Device identification functions like print_dev_t, format_dev_t
• User space to kernel space data length and permission checking with strnlen_user
• Helper function for type casting with container_of
• Access control checks with access_ok

📦 Commands used in this course: You'll also get hands-on practice with essential Linux commands:

• mknod for creating device files manually.
• udevadm monitor to dynamically create device nodes with udev.

By the end of this course, you'll be equipped with the knowledge and skills to develop character device drivers for the Linux kernel, enabling you to create your own devices or contribute to open-source projects that require a deep understanding of this topic. 👩‍💻🚀