Writing Network Device Drivers for Linux LG 1. By Mohan Lal Jangir. Introduction. This article has been written for kernel newcomers interested in. It assumes that reader has a. Advanced C programming course skims through the basics of C and soon jumps over to core of C programming language which looks simple but difficult to master. C and the Linux environment. This article is based on a network driver for the Real. Tek 8. 13. 9 network. I chose the Real. Tek chip for two reasons First, Real. Tek provides. technical specifications for its chips free of cost. Thanks, Real. Tek. Second its quite cheap. It is possible to get the chip under Rs 3. US7 in Indian markets. Makes TASKING brand IDE, compiler, debugger, embedded Internet and RTOS offerings, support wide range of DSP and 81632bit microprocessors and microcontrollers for. Fulltext of the book by Alessandro Rubini and Jonathan Corbet, in a variety of formats. Driver Installation Instructions SPMU287BAugust 2012Revised January 2014 Stellaris InCircuit Debug Interface ICDI and Virtual COM Port. Learns C, C, STL and other C C related programming tutorail through program examples and experiments from beginner to advanced. C Device Driver Programming Tutorial' title='C Device Driver Programming Tutorial' />The driver presented in this article is minimal it simply sends and. For a full fledged and. Linux source. Preparing for Driver Development. Before starting driver development, we need to set up our system for it. This article was written and tested on Linux 2. Real. Tek. 81. 39 chip driver. Its very likely that the. Its advisable to build a kernel which does. Real. Tek. 81. 39 driver in any form, to avert unnecessary. If you dont know how to recompile the Linux kernel, I. From this point of discussion onwards, it is assumed that you have a working. Real. Tek. 81. 39. Youll also need the. The last. activity in this series is to properly insert the NIC into the PCI slot, and. It is strongly recommended to have Rubinis Linux Device Drivers book. API reference. This is the best resource known to me for. Linux device driver development, as of now. Starting Driver Development. Driver development breaks down into the following steps. Detecting the device. Enabling the device. Understanding the network device. Bus independent device access. Understanding the PCI configuration space. Initializing netdevice. Understanding Real. Tek. 81. 39s transmission mechanism. Understanding Real. Tek. 81. 39s receiving mechanism. Making the device ready to transmit packets. Making the device ready to receive packets. Detecting the Device. As a first step, we need to detect the device of our interest. The Linux kernel. APIs to detect a device over the PCI bus Plug Play. API is pcifinddevice. REALTEKVENDERID 0x. EC. define REALTEKDEVICEID 0x. REALTEKVENDERID, REALTEKDEVICEID, NULL. Device not foundn. Device foundn. Table 1 Detecting the device. Each vendor has a unique ID assigned, and each vendor assigns a unique ID to a. The macros REALTEKVENDERID and REALTEKDEVICEID. IDs. You can find these values from the PCI Configuration. Space Table in the Real. Tek. 81. 39 specifications. Enabling the Device. After detecting the device, we need to enable the device before starting any. The code snippet shown in. Table 1 can be extended for device detection and enabling the device. NULL. Ensure we are not working on a non PCI system LOGMSGlt 1 pci not presentn. REALTEKVENDERID 0x. EC. define REALTEKDEVICEID 0. X8. 13. 9. Look for Real. Tek 8. 13. 9 NIC. REALTEKVENDERID, REALTEKDEVICEID, NULL. LOGMSGCould not enable the devicen. NULL. else. LOGMSGDevice enabledn. LOGMSGdevice not foundn. Table 2 Detecting and Enabling the Device. In Table 2, the function probeforrealtek. Ensures that we are working on a PCI capable system. NULL if system does not have PCI. Detects the Real. Tek 8. 13. 9 device as explained in Table 1. Enables the device by calling pcienabledevice, if. For time being, we temporarily suspend the thread of driver code study. Linux view of a network device. We will look at network devices, and the. IO, port mapped IO, and PCI. Understanding Network Devices. We have detected the PCI device and enabled it, but the networking stack. Linux sees interfaces as network devices. This is represented by the. This means that the networking stack issues. PCI device. Table 3 lists. MAXADDRLEN. unsigned char broadcastMAXADDRLEN. Table 3 Structure netdevice. Although this structure has many more members, for our minimal driver. The following section describes the structure. The name of the device. If the first character of the name. For example, if your system already has eth. The IO base address. We will discuss more. IO addresses later in this article. Hardware address MAC address length. It is 6. for Ethernet interfaces. Hardware address Ethernet address or MAC. It is. FF FF FF FF FF FF for Ethernet interfaces. The hardware header length is the. IP header, or other. The value of hardheaderlen is 1. Ethernet. irq The assigned interrupt number. This is a pointer to a function that opens the. This function is called whenever ifconfig activates the device for. The open method should register any system. IO ports, IRQ, DMA, etc., turn on the hardware and. Mogali Rekulu Serial All Episodes. This is a pointer to a function that stops the. This function is called whenever ifconfig deactivates the device. The stop method releases all the resources. This function transfers a given packet. The first argument of the function is a pointer to structure. Structure skbuff is used to hold packets in Linux networking stacks. Although this article does not require detailed knowledge about. LDPkhgHyper. Newsgetnetnet intro. This function provides interfaces statistics. The output of the command ifconfig eth. Private data to the driver. The driver owns this field. We will see later that our driver uses this field to. PCI devices. Although we have not mentioned all members of the netdevice structure. This is done by the device interrupt handler, as we will see later in this. Bus Independent Device Access. Note This section has been taken from Alan Coxs book Bus Independent. Device Accesses available at http tali. Linux provides an API set that abstracts performing IO operations across all. Memory Mapped IO. The most widely supported form of IO is memory mapped IO. That is, a part of. CPUs address space is interpreted not as accesses to memory, but as. Some architectures define devices to be at a fixed. The PCI bus walk is a. This document does not cover how to receive such. Physical addresses are of type unsigned long. These addresses should not be. Instead, to get an address suitable for passing to the functions. An address suitable for accessing the. After youve finished using the device say, in your modules exit routine. Most. architectures allocate new address space each time you call ioremap, and they. Accessing the device. The part of the interface most used by drivers is reading and writing. Linux provides interfaces to read. Due to a. historical accident, these are named byte, word, long, and quad. Both read and write accesses are supported there is no. The functions are named readb, readw. Some devices such as framebuffers would like to use larger transfers that. For these devices, the memcpytoio. Do not use memset or memcpy. IO addresses they are not guaranteed to copy data in order. The read and write functions are defined to be ordered. That is, the compiler. IO sequence. When the ordering can be compiler. Use. this with care. The rmb provides a read memory barrier. The wmb provides a write. While the basic functions are defined to be synchronous with respect to each. In particular many authors are not comfortable. PCI bus writes are posted asynchronously. An author of the. This kind of property cannot be. API. Port Space Access. Another form of IO commonly supported is Port Space. This is a range of. Access to these. addresses is generally not as fast as accesses to the memory mapped addresses. Unlike with memory mapped IO, no preparation is required to access port space. Accessing Port Space or IO mapped devices. Accesses to this space are provided through a set of functions which allow. A to Z of C Beta 1. Acknowledgement. 1. Book Organization. FAQ about A to Z of C 3. Indian Hill Style. Hungarian Coding Style. WAR Wesley And Rajesh Coding Style. Part IANSI C 4. 1 Myth Mistakes. Tips for better Programming. Coding Style. 4. 2. Boolean Variables. How to code betterWhat main returns Arguments of main 5. Example. 6. 2 Frequently Asked Undefined Questions 7. Swap Macro. 7. 2 Flip and Flop. Crypting with XOR 8. Factorial. 9. 2 Fibonacci. GCD9. 4 Power. 9. Reverse Printing. Decimal to binary conversion. Decimal to hexadecimal conversion. Printing a decimal in words 1. Power of 2. 10. 2 Prime Numbers. Roman Letters   convert Arabic numerals to Roman numerals1. Day of Week. 10. 5 Calendar. Memory Swap. 10. Block Structure. Swap macro using Block Structure. Printf with b 1. Self replicating program 1. Self replicating program 2. Self replicating program 3 1. Memory Overwrite. ArrayBuffer Overflow. Memory Leak. 12. 4 Multidimensional array implementation. Version 1. 12. 4. Version 2. 12. 4. Version 3. 12. 4. Version 4. 12. 5 Linked List 1. Where to contest Guidelines. Real Code. Wherami. Note. Part IIDOS Programming 1. Prelude. 14. 1. 1 BIOS1. Bootstrap Program. Boot Sector. 14. 2 Memory Layout. Upper Memory Area UMA1. Segment Address. 14. Extended Memory. 14. Limitations of DOS 1. Features of TC3. Configure your TC3. IDE basics. 15. 4 Useful Utilities. BASM1. 5. 4. 2 TASM1. TLINK1. 5. 4. 4 TLIB1. MAKE1. 5. 4. 6 TCC1. Preprocessor. 15. Header file. 15. 8 Pragma. Example 1. 15. 8. Example 2. 15. 9 Creating library file. Creating a project file. Turbo C keywords. Bugs Remedy. Floating point formats not linked. Null pointer assignment 1. Inline Assembly. 16. Example 1. 16. 1. Example 2. 16. 1. Usual Errors. 16. Calling Assembly routines from C1. Cs calling convention. Cs naming convention. Example 1. 16. 2. Example 2. 16. 3 Creating library file out of assembly language module 1. Processors. 17. 2 Processor Modes. Real Mode. 17. 2. Protected Mode. 17. Virtual Real Mode. Processor Type. 17. C program to find processor type. Assembly routine to find processor type. Another Assembly routine 1. Example 1. 9. 1 Logical outline of interrupt routine. Interrupt Classification. Programming with interrupts. Inline Assembly Style. Pure Assembly Style. Benchmarking. 19. Myth Mistakes 2. Memory map. Programming the video RAM2. Color Text Mode. 20. Monochrome Text Mode. Graphics Mode 2. 1. Why use ports 2. Port vs. Usual Problems. 21. Programming ports with Turbo C2. Example 2. 2. 1 Secrets. Keyboard controller. Keyboard Buffer. 22. Keyboard status. 22. Keyboard Interrupt. Activating the keys without pressing it Stuff keys using BIOS interrupt. Stuff keys using keyboard buffer. Multiple key Input 2. Introduction. 23. Programming PIT2. Producing Sound. 23. Notes Frequencies. Piano Keys and Frequencies. Piano Program 2. 4. Idea 2. 5. 1 Mouse Interrupts. Useful Mouse functions. Mouselib. h. 25. 2. Mouselib. c. 25. 2. Mouselib. lib. 25. Mouse Function 0. Ch. 25. 4 Request Mode or Event ModeRebooting with pointers. Identifying machine model and BIOS date 2. DOSs non reentrancy Problem. Switching Programs. DOS Busy Flag. 27. BIOS Functions. 27. Popping up TSR2. 7. IBMs Interrupt Sharing Protocol. Rules for TSR Programming. TSR Template. 27. PC PILOTSource code with EXE   zip, 4. KBPart IIIAdvanced Graphics Programming 2. Common Mistake 2. More Colors. 28. 3 Jordan Hargraphix Softwares Super. VGATweak BGI drivers. Jordan Hargraphix Softwares HGXMOUSE TSR 2. Paintbrush. 29. 1. Restricting Mouse Pointer. HidingShowing Mouse Pointer. Avoiding Flickering of Mouse Pointer. Using setwritemode function. Note. Source code with EXE   zip, 3. KB 3. 0. Scribble   CHR file creatorBGI font file creator 3. Prelude. 30. 2 Storing Fonts. Scribble screenshots. Mouselib. lib. 30. Mouselib. h. 30. 4. Mouselib. c. 30. 4. Mouselib. lib. 30. Scribble. h. 30. 6 Scribble. Scribble. prj. Source code with EXE   zip, 8. KB 3. 1. 1 Important Notice. GIFSAVE3. 1. 3 Gifsave. Gifsave. c. 31. 5 Example usage of GIFSAVE 3. Mode 1. 3h. 32. 1. Palette Register. Vertical Retrace. Optimization Note 3. Programs 3. 4. 1 Extracting Palette. PAL Utility. 34. 1. Using PAL3. 4. 2 Fire Program. Source code with EXE   zip, 2. KB 3. 5. 1 Secrets. Program 3. 6. 1 Perspective Projection. D Rectangle 3. 7. Prelude. 37. 2 Program. Part IVAdvanced Programming 3. Graphics Mode. 38. Logic. 38. 3 Alexander Russells Guide 3. Interfacing LCD with parallel port. Circuit Diagrams. Logic. 39. 1. 3 Program 4. PROM4. 0. 2 EPROM4. EEPROM4. 0. 4 Programming for Embedded Systems. Locate utility. 40. ROMable Code. 40. Applications 4. 1. BIOS Code. 41. 2 Flash BIOS4. Uniflash. Source code ASM   zip, 3. KB 4. 2. 1 Viewing contents of CMOS RAM4. Logic. 42. 1. 2 Code. Diagnose CMOS RAM4. Logic. 42. 2. 2 Code. Source code   zip, 5. KB 4. 3. 1 Secrets. Types of MS DOS device drivers. Character device drivers. Block device drivers. Writing our own device driver. BUF1. 60. 43. 4. 1 Source code. Compiling BUF1. 60. Installing BUF1. 60. BGI Driver 4. 4. 1 Novell Netware. Network Library. 44. Example Toserver. Example Ulist. c. Windows NTNote Adrian Cunnelly, author of Netware C Library has informed us about the newfreebetter version. File can be downloaded here. KB 4. 5. 1 TCPIP Programming. WATTCP4. 5. 2 Programming Browser 4. Basic Idea 4. 6. Developing a new Protocol 4. EZOS8. 64. 7. 1. Notes. Kernel Source Code. Good Luck Source code version 2   zip, 1. KB 4. 8. 1 Secrets. Writing a compiler. Compiler. 48. 2. 2 Compiler Secrets. Compiler writing tools. YACC4. 8. 3. 3 Creating Compiler with lex YACC 4. Prelude. 49. 2 BYACC4. Brief History. 49. Source code. 49. 2. Compiling BYACC 5. Basic Idea. 50. 2 File format for DBF file. Security 5. 1. 1 Basic Idea. DCC5. 1. 2. 1 Disclaimer. Notice. 51. 2. 3 DCC Facts. Example of Decompilation 5. Prelude. 52. 2 Secrets. Table. c. 52. 3. 2 Disasm. Types of Printers. Dot Matrix Printers. Inkjet Printers. 53. Laser Printers. 53. Printer Languages. Page Description Language. Escape Codes. 53. Printing non printable characters. Epson Extended Character Set. Graphics Mode. 53. Font Map. 53. 3. 4 Optimization Tip. Program. Source code with EXE   zip, 1. KBPart VMathematics C 5. Range reduction and Chebychev polynomial approximation. CORDIC Method 5. 5. Program 5. 6. 1 Program. Numerical Analysis 5. Program 5. 8. 1 Oudins Algorithm. Easter Day Program. Part VIAlgorithms C 5. Birth of CORDIC5. Advantages. 59. 3 Principle. Algorithm. 59. 5 Program. Brief History. 60. Principle behind LZW6. LZW Compression. 60. Compression Algorithm. Example. 60. 4 LZW Decompression. Decompression Algorithm. Example 6. 1. 1 Recursive Maze Algorithm. Maze. 61. 3 Principle of Maze. Program. Part VIIIllegal Codes 6. Bypass System password. Default master password. Hardware techniques clearing CMOS RAM6. Bypass Setup password. Default master password. Program 6. 3. 1 Brute force technique. Dictionary attack 6. Cracking ZIP passwords. Crack. It. 64. 2. Logic. 64. 2. 2 Code 6. Novell Netware. 65. Fake Prompts. 65. TSR program. 65. 1. Brute force Cracking. Cracking from password file. Windows NT 6. 6. 1 DEBUG6. Finding out Signature. Algorithms. 66. 4 Standard Format 6. Logic. 67. 2 TSR viruses. Windows viruses. 67. Anti Viruses. Part VIIINext Step 6. Compiler. 68. 2 3. Compiler DJGPP6. Allegro 6. C6. Java. 69. 3 C6. DPart IXSmart Dictionary 7. Notations. 71. 2 Interrupt List. Overview. 71. 2. 2 Listing. Port listing. 71. Notations. 71. 3. Listing. 71. 4 Memory map. Other resources 7.