linux device drivers 4th edition pdf free download

... for the same device) is best solved by implementing one device node for each access policy. An example of this practice can be found in the Linux tape driver, which provides multiple device files ... same device. Differ ent device files will, for example, cause the drive to record with or without compression, or to automatically rewind the tape when the device is closed. Cloning the Device ... struct file *filp) { /* * Nothing to do, because the device is persistent. * A ‘real’ cloned device should be freed on last close Access Control on a Device File 171 22 June 2001 16:36 Chapter 5: Enhanced

Ngày tải lên: 13/08/2014, 21:21

... and used by device drivers. The allocator module, part of the sample code released on the O’Reilly FTP site, of fers an allocation interface to manage any high memory not used by the Linux ker ... mapping obtained with vr emap would be freed with vfr ee. Also, the header <linux/vmalloc.h> didn’t exist in 2.0; the functions were declar ed by <linux/mm.h> instead. As usual, sysdep.h ... <linux/vmalloc.h> if <linux/mm.h> is included, thus hiding this differ ence as well. Quick Reference The functions and symbols related to memory allocation follow. #include <linux/malloc.h>

Ngày tải lên: 13/08/2014, 21:21

... conflicting access to the device itself void sbull_request(request_queue_t *q) { Sbull_Dev *device; struct request *req; int status; /* Find our device */ device = sbull_locate_device (blkdev_entry_next_request(&q->queue_head)); ... Sbull_Dev *device = sbull_devices + MINOR(bh->b_rdev); ptr = device->data + bh->b_rsector * sbull_hardsect; /* Paranoid check; this apparently can really happen */ if (ptr + bh->b_size > device->data ... sbull’s queue function looks like this: request_queue_t *sbull_find_queue(kdev_t device) { int devno = DEVICE_NR(device); if (devno >= sbull_devs) { static int count = 0; if (count++ < 5) /* print

Ngày tải lên: 13/08/2014, 21:21

... 85-91 drivers/ block directory, 518 drivers/ cdrom directory, 520 drivers/ char directory, 518 drivers/ i2c directory, 524 drivers/ ide directory, 519 drivers/ input directory, 523 drivers/ ... hardware-dependent device drivers you would expect to find in drivers/block, the directory also includes software device drivers that are inher ently cr oss-platform, just like the sbull and spull drivers ... 329, 367 device memory (see I/O memory) DEVICE_ NAME symbol, 329, 367 DEVICE_ NO_RANDOM symbol, 329 DEVICE_ NR symbol, 329, 367 minor_shift value and, 356 DEVICE_ OFF macro, 329 DEVICE_

Ngày tải lên: 13/08/2014, 21:21

... INTRODUCTION TO DEVICE DRIVERS As the popularity of the Linux system continues to grow, the interest in writing Linux device drivers steadily increases Most of Linux is independent ... independent of the devices attached to the SCSI cable Other classes of device drivers have been added to the kernel in recent times, including USB drivers, FireWire drivers, and I2O drivers In ... modularity makes Linux drivers easy to write, to the point that there are now hundreds of them available There are a number of reasons to be interested in the writing of Linux device drivers

Ngày tải lên: 13/08/2014, 21:21

... {device} [0-3] major=‘awk "\\ $2= =\"$module\" {print \\$1}" /proc/devices‘ mknod mknod mknod mknod /dev/$ {device} 0 /dev/$ {device} 1 /dev/$ {device} 2 /dev/$ {device} 3 c c c c... the device ... to user programs. Since our “device” is part of the computer’s memory, we’re free to do what we want with it. It can be a sequential or random- access device, one device or many, and so on. To ... in the device file entries before the date of last modification, where the file length nor mally appears. These numbers are the major device number and minor device number for the particular device.

Ngày tải lên: 13/08/2014, 21:21

... dad_close (struct inode *inode, struct file *filp) { struct dad _device *my _device; /* */ free_dma(my _device. dma); free_irq(my _device. irq, NULL); /* */ } As far as /pr oc/dma is concerned, ... data transfers If you are writing device drivers for ISA device boards,... only thing that remains to be done is to configure the device board This device- specific task usually consists ... kiobuf mechanism. It is worth noting that in Linux systems, there is no need for block drivers to pro- vide this sort of interface. The raw device, in drivers/char/raw.c, provides this capability

Ngày tải lên: 13/08/2014, 21:21

... might have expected. Differences in Linux 2.2 First of all, Linux 2.3.14 renamed the network device structure, which had always been struct device,tostruct net_device. The new name is certainly ... unregister_netdev(struct net _device *dev); Register and unregister a network device SET_MODULE_OWNER(struct... up to 32 devices, and each device can be a multifunction board (such as an audio device with ... registers of each device, one file per device * You’ll find the ID of any device in its own hardware manual A list... on a bus /device pair The devfn argument represents both the device and function

Ngày tải lên: 13/08/2014, 21:21

... Chapter :An Introduction to Device Drivers As the popularity of the Linux system continues to grow, the interest in writing Linux device drivers steadily increases Most of Linux is independent of ... supported by Linux, somebody somewhere has written a driver to make it work with the system Without device drivers, there is no functioning system Device drivers take on a special role in the Linux ... independent of the devices attached to the SCSI cable Other classes of device drivers have been added to the kernel in recent times, including USB drivers, FireWire drivers, and I2O drivers In the

Ngày tải lên: 24/12/2013, 01:17

... O'Reilly FTP site, as explained in Chapter 1, "An Introduction to Device Drivers". #define MODULE #include <linux/module.h> int init_module(void) { printk("<1>Hello, ... include/linux and include/asm inside the kernel sources (usually found in /usr/src/linux). Older distributions (based on libc version 5 or earlier) used to carry symbolic links from /usr/include/linuxand ... expect. The hard part is understanding your device and how to maximize performance. We'll go deeper into modularization throughout this chapter and leave device-specific issues to later chapters.

Ngày tải lên: 24/12/2013, 01:17

... 3: Char Drivers The goal of this chapter is to write a complete char device driver We'll develop a character driver because this class is suitable for most simple hardware devices Char drivers ... offer to user programs Since our "device" is part of the computer's memory, we're free to what we want with it It can be a sequential or random-access device, one device or many, and so on To make ... length normally appears These numbers are the major device number and minor device number for the particular device The following listing shows a few devices as they appear on a typical system Their

Ngày tải lên: 24/12/2013, 01:17

... exit(1); } exit(0); } setconsole uses the special ioctl command TIOCLINUX, which implements Linux-specific functions. To use TIOCLINUX, you pass it an argument that is a pointer to a byte array. ... To select a different virtual terminal to receive messages, you can issue ioctl(TIOCLINUX) on any console device. The following program, setconsole, can be used to choose which console receives ... arg\n",argv[0]); exit(1); } if (ioctl(STDIN_FILENO, TIOCLINUX, bytes)<0) { /* use stdin */ fprintf(stderr,"%s: ioctl(stdin, TIOCLINUX): %s\n", argv[0], strerror(errno)); exit(1);

Ngày tải lên: 24/12/2013, 01:17

... Seeking in Linux 2.0 Prior to Linux 2.1, the llseek device method was called lseek instead, and it received different parameters from the current implementation For that reason, under Linux 2.0 ... Nonetheless, sometimes it's a useful approach to device control and is used by tty's and other devices We'll describe it later in this chapter in "Device Control Without ioctl" As we suggested in ... first versions of Linux used 16-bit numbers: the top eight were the "magic'' number associated with the device, and the bottom eight were a sequential number, unique within the device This happened

Ngày tải lên: 24/12/2013, 01:17

... discussion of device methods. static int scull_c_release(struct inode *inode, struct file *filp) { /* * Nothing to do, because the device is persistent. * A `real' cloned device should be freed ... there. The devices are released when scull_cleanup is called. This code uses the generic Linux linked list mechanism in preference to reimple- menting the same capability from scratch. Linux lists ... release the device */ return 0; } Normally, we recommend that you put the open flag scull_s_available within the device structure ( Scull_Dev here) because, conceptually, it belongs to the device. ...

Ngày tải lên: 09/08/2014, 04:21

... of the Book, eMatter Edition Copyright â 2005 O’Reilly & Associates, Inc. All rights reserved. Classes of Devices and Modules | 7 Block devices Like char devices, block devices are accessed ... reader), or a network device (a USB Ethernet interface). Other classes of device drivers have been added to the kernel in recent times, includ- ing FireWire drivers and I2O drivers. In the same ... code without being overwhelmed by com- plexity. Often, device drivers provide that gateway. Device drivers take on a special role in the Linux kernel. They are distinct “black boxes” that make...

Ngày tải lên: 21/02/2014, 19:20

... device_ close instead of device_ release. Either way, the device method should perfor m the following tasks: ã Deallocate anything that open allocated in filp->private_data ã Shut down the device ... THREE CHAR DRIVERS The goal of this chapter is to write a complete char device driver. We’ll develop a character driver because this class is suitable for most simple hardware devices. Char drivers ... to user programs. Since our device is part of the computer’s memory, we’re free to do what we want with it. It can be a sequential or random- access device, one device or many, and so on. To...

Ngày tải lên: 25/03/2014, 10:48

... code without being overwhelmed by com- plexity. Often, device drivers provide that gateway. Device drivers take on a special role in the Linux kernel. They are distinct “black boxes” that make ... more and more functionality in Linux is being modularized. Classes of Devices and Modules The Linux way of looking at devices distinguishes between three fundamental device types. Each module usually ... of the Book, eMatter Edition Copyright â 2010 O’Reilly & Associates, Inc. All rights reserved. Classes of Devices and Modules | 7 Block devices Like char devices, block devices are accessed...

Ngày tải lên: 24/04/2014, 15:28

... of the Book, eMatter Edition Copyright â 2005 O’Reilly & Associates, Inc. All rights reserved. 8 | Chapter 1: An Introduction to Device Drivers In addition to device drivers, other functionalities, ... writing drivers for PCI devices, and Chapter 13 examines the API for working with USB devices. With an understanding of peripheral buses in place, we can take a detailed look at the Linux device ... plan for the fourth edition, and look for a fourth author to help. Greg’s Introduction It seems like a long time ago that I picked up the first edition of this Linux Device Drivers book in order...

Ngày tải lên: 09/08/2014, 04:21

... -f /dev/$ {device} [0-3] major=$(awk "\\$2= =\"$module\" {print \\$1}" /proc/devices) mknod /dev/$ {device} 0 c $major 0 mknod /dev/$ {device} 1 c $major 1 mknod /dev/$ {device} 2 ... the cdev structure, num is the first device number to which this device responds, and count is the number of device numbers that should be associated with the device. Often count is one, but there ... option. CONFIG_INPUT_EVBUG This option (under Device drivers/ Input device support”) turns on verbose log- ging of input events. If you are working on a driver for an input device, this option may be helpful....

Ngày tải lên: 09/08/2014, 04:21

... scull_nr_devs; i++) { scull_devices[i].quantum = scull_quantum; scull_devices[i].qset = scull_qset; init_MUTEX(&scull_devices[i].sem); scull_setup_cdev(&scull_devices[i], i); } Note that ... implementing device control this way is that the user can control the device just by writing data, without needing to use (or sometimes write) programs built just for configuring the device. When devices ... the two techniques would be avoided. Device Control Without ioctl Sometimes controlling the device is better accomplished by writing control sequences to the device itself. For example, this technique...

Ngày tải lên: 09/08/2014, 04:21