How to write a kernel module that creates a directory in /proc named mymod and a file in it name is mymodfile. This file should accept a number ranged from 1 to 3 when written into it and return the following messages when read based on the number already written into it:

• 1: Current system time (in microseconds precision)
• 2: System uptime
• 3: Number of processes currently in the system

“The Output”

root@Paradise# echo 1 > /proc/mymod/mymodfile
root@Paradise# cat /proc/mymod/mymodfile
08:30:24 342us
root@Paradise# echo 2 > /proc/mymod/mymodfile
root@Paradise# cat /proc/mymod/mymodfile
up 1 day, 8 min 
root@Paradise# echo 3 > /proc/mymod/mymodfile
root@Paradise# cat /proc/mymod/mymodfile
process count: 48 

please give me some hint how to write a kernel modules and how to compile and install it .