This document discusses Linux device drivers. It provides an overview of the history and purpose of Linux and device drivers. It explains that device drivers connect hardware and software by communicating at both the logical and physical layers. It also describes the difference between kernel and user modes, and discusses how device drivers are developed by utilizing Linux system calls and supporting development environments within the Linux kernel programming interface.

1. Linux Device Driver

2. Agenda
 History & Why Linux kernel?
 Device Driver.
 Purpose & Design
 Kernel mode & User mode
 Development
 Application & API

3. History and Why Linux kernel?
 First developed by Linus Torvals.
 Linux base on UNIX standard.
 Workgroup for implement driver
& patch with kernel.org.
 ”Just for fun” - Linux Torvals
History.

4. Pupose & Design
 Connection between Hardware and Software.
 Design communicate on logical
layer ( Port : ttyS,lp,hd) and
physical layer(Handle stardard
of communication protocol).
 Linux kernel (.ko file type) &
Microsoft (.sys file type )
kernel( Monolithic,Micro,Hybird
)

5. Linux boot sequence on x86
x86 Real Mode
BIOS
Bootloader ( GRUB/LILO )
Real Mode Kernel
X86 Protected
Arch/x86/boot/pm.c Mode
Protected Mode kernel
The init Process
User Processes and Daemons
Booting up,Essential Linux Device Drivers-Venkateswaran.

6. User & Kernel mode.

Kernel Mode
 It can execute any CPU instruction and reference
any memory address. Kernel mode is generally
reserved for the lowest-level”.
 Most, ”trusted functions of the operating system”.

User Mode
 In User mode, the executing code has no ability to
directly access hardware or reference memory.
 Code running in user mode must delegate to
system APIs to access hardware or memory.
Understanding user & kernel mode,Coding Horror-Jeff Atwood

7. Development
 Linux System Call.
 Device Drivers Development Supporting device
drivers.
 Kernel Programming Environment.

8. Linux System Call
 Executing in kernel mode.
 Kernel mode recognize and particular action
is require from the device.
 Call to device routine which pass user
process to device routine.
 Device routine may be shared
simulataneously by user application

9. Device Drivers Development
Supporting device drivers.
 A set of routines that communicate with a hardware
device and provide a uniform interface to the operating
system kernel.
 A self-contained component that can be added to, or
removed from, the operating system dynamically.
 Management of data flow and c ontrol between user
programs and a peripheral device.
 A user-defined section of the kernel that allows a
program or a peripheral device to appear as a `` /dev
'' device to the rest of the system's software.
Write a Linux Hardware Device Driver.FreeSoftware Mag.

10. Device Driver Programming
% make
#include <linux/init.h>
#include <linux/module.h> make[1]: Entering directory `/usr/src/linux-2.6.10'
MODULE_LICENSE("Dual BSD/GPL"); CC [M] /home/ldd3/src/misc-modules/hello.o
Building modules, stage 2.
static int hello_init(void) MODPOST
{ CC
printk(KERN_ALERT "Hello, worldn");
/home/ldd3/src/misc-modules/hello.mod.o
return 0;
LD [M] /home/ldd3/src/misc-modules/hello.ko
}
make[1]: Leaving directory `/usr/src/linux-2.6.10'
static void hello_exit(void) % su
{ root# insmod ./hello.ko
printk(KERN_ALERT "Goodbye, cruel worldn"); Hello, world
} root# rmmod hello
Goodbye cruel world
module_init(hello_init);
root#
module_exit(hello_exit);
Linux kernel in a nutshell,3rd-Greg Kroah-Hartman