Examples of character device driver in linux

 · Device drivers have an associated major and minor number. For example, /dev/ram0 and /dev/null are associated with a driver with major number 1, and /dev/tty0 and /dev/ttyS0 are associated with a driver with major number 4. The major number is used by the kernel to identify the correct device driver when the device is accessed.  · You could do the get_user in a loop, but invocations of the function is probably not super efficient. You can do it all in one shot with the following approach. First of all, you need to copy_from_user the buf into a kernel-side buffer. You don't know the size of the buffer ahead of time, so you should k/vmalloc it (EDIT: you can skip the memory allocation since your data is Reviews: 1.  · Linux Character Device Example · GitHub. # include. # include. # include. # include /* for put_user */ /* * Prototypes - this would normally go in a.h file */ int init_module (void); void # define SUCCESS 0.

In this post, we would be writing a Linux device driver for a hypothetical character device which reverses any string that is given to it. i.e. If we write any string to the device file represented by the device and then read that file, we get the string written earlier but reversed (for eg., myDev being our device, echo “hello” /dev/myDev ; cat /dev/ myDev would print “olleh”). There are two ways of programming a Linux device driver: Compile the driver along with the kernel, which is monolithic in Linux. Implement the driver as a kernel module, in which case you won’t need to recompile the kernel. This article, which is part of the series on Linux device drivers, deals with the various concepts related to character drivers and their implementation. Shweta, at her PC in her hostel room, was all set to explore the characters of Linux character drivers, before it was taught in class.

Device drivers take on a special role in the Linux kernel. (/dev/console) and the serial ports (/dev/ttyS0 and friends) are examples of char devices. In our character driver we are keeping name of our device is “mydev”. #include Below is the example of make file. Examples for Character Devices: serial ports, parallel ports, sounds cards. Examples for Block Devices: hard disks, USB cameras, Disk-On-Key. For the user, the.