linux device drivers 3rd edition

No_llseek Access control for device files Exclusive equipment The most blunt method of access control is to allow only one process to open the device at a time Restrict access by only one user at a time Requires two data items An open count UID of the device owner

Preface Linux is a variant of the UNIX operating system, and the principle and idea of writing a driver in Linux is similar to that of other Unix systems, but it is very different for drivers in DOS or window environments. Design the driver in the Linux environment, the thought is concise, the operation is convenient,

atomic items that must be transmitted, and the direction of the transmission void Set_dma_mode (unsigned int channel, char mode); Mode Dma_mode_read Dma_mode_write Dma_mode_cascade Release control of the bus void set_dma_addr (unsigned int channel, unsigned int addr); void Set_dma_count (unsigned int channel, unsigne

describes how an Ethernet transceiver is connected to a network controller Int (*mdio_read) (struct net_device *dev, int phy_id, int location); void (*mdio_write) (struct net_device *dev, int phy_id, int location, int val); Drivers/net/mii.c Ethtool Support Ethtool is a tool for system administrators to control network interfaces Use Ethtool to control many interface parameters inc

---restore content starts---Linux device driversOne, the role of device-drivenThe most popular explanation for device drivers is " Drive hardware Device Actions ". Drive and the underlying hardware directly to deal with, according

function defined. The kernel assigns an empty page to it.*/struct page * (*nopage) (struct vm_area_struct *vma, unsigned long address, int *type);/* Before the User space access page. The function agrees that the kernel will pre-load these pages into memory.*/Int (*populate) (struct vm_area_struct *vm, unsigned long address, unsigned long len, pgprot_t prot, unsigned long pgoff, I NT Nonblock);Memory-mapped processingEach process in the system (in addition to some of the auxiliary threads in th

　　 Step 2: Create the int init_test (void) function) Register the device here: Result = register_chrdev (254, "test", test_fops ); 　　 (2) set test. copy c to the/uclinux/linux/drivers/char directory, and mem in the/uclinux/linux/drivers/char directo

the device here: Result = register_chrdev (254, "test", test_fops ); 　　 　　 (2) set test. copy c to the/uclinux/linux/drivers/char directory, and mem in the/uclinux/linux/drivers/char directory. in c, add the following code to the int chr_dev_init () function: # Ifdef CONFI

Sys_select ()------> Do_select ()The final call to the file descriptor fd corresponds to the struct file type variable of the struct file_operations *f_op of the poll function.The function that poll points to returns information that is currently read and written.1) returns read and write information if it is currently readable or writable.2) If it is not currently read/write, block the process and wait for the driver to wake up, call the poll function again, or return the timeout.3, the driver

distinguish between different kinds of devices, while the secondary device number is used to differentiate multiple devices of the same type.The Linux kernel uses a virtual file system (SYSTEM,VFS) as an interface for interacting with each file system. This provides a standard interface for any type of file system communication within Linux. When each file syste

In the Linux kernel, The framebuffer (POST buffer) driver is the display driver standard. framebuffer abstracts the display device as the POST buffer. After the user maps the memory to the process address space, you can directly perform read/write operations, and write operations can be immediately displayed on the screen. Related display drivers and interfaces a

*/Unregister_chrdev_region (MKDEV (mem_major, 0), 2); /* Release the device number */}Module_author ("David Xie");Module_license ("GPL");Module_init (Memdev_init);Module_exit (Memdev_exit);(3) app-ioctl.c(application)#include #include #include #include #include "memdev.h"/* contains the command definition */int main (){int fd = 0;int cmd;int arg = 0;Char buf[4096]; /* Open the device file */FD = ope

1.1 Linux device driver classification Linux device drivers occupy a large proportion of the Linux kernel source code, and the length of the source code is increasing, mainly the increase of the driver. During the continuous upgr

Relationship between Linux Device Drivers and the entire hardware System 1. device classification and features the hardware of a computer system consists of CPU, memory, and peripherals. With the development of the IC (Integratedcircuit) manufacturing process, the current chip integration is getting higher and higher,

blocking and non-blocking IO in Linux device drivers:Blocking and non-blocking in 1.Linux device drivers Summary: http://m.blog.csdn.net/blog/dongteen/17264501Blocking and non-blocking io:http://m.blog.csdn.net/blog/dongteen/17264501 in 2.

the methods in the previous chapter to see information about this device in SYSFS:# Ls/sys/block/simp_blkdevDev holders range removable size slaves stat subsystem uevent#We found that our driver was missing the queue subdirectory in the SYSFS directory.It's not surprising, or it's going to freak out.In this chapter we implement our own make_request function to deal with bio, which is to get rid of the I/O Scheduler and the General __make_request () o

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}};static struct Dm9000_plat_data Mini2440_dm9k_pdata = {The number of digits in the data line is 16 bits, and no e2prom is used. Flags = (Dm9000_platf_16bitonly | Dm9000_platf_no_eeprom),. dev_addr = {0x08,0x90,0x90,0x90,0x90,0x90},//mac address};static struct Platform_device Mini2440_device_eth = {. Name = "dm9000",//device name. id =-1,. num_resources = Array_size (Mini2440_dm9k_resource),. Resource = Mini2440_dm9k_resource,//Resources. Dev = {. Pl

It may be difficult to put the driver model in the first chapter, but as long as the driver model can be crossed, it will be much easier later. The driver model is the cornerstone of the entire Linux Device Driver. Most people call the driver model a device model, but I have checked the help document of Linux to find t

Basic conceptsBlock Devices (Blockdevice)---is a random access device with a certain structure, the reading and writing of this device is block -based, he uses buffer zone to hold temporary data, waiting for the condition to mature, from the cache once written to the device or from the device to read the buffer at once