developing linux device drivers using libusb programming interface

Tài liệu Linux Device Drivers-Chapter 1 :An Introduction to Device Drivers ppt

... an interface, that is, a device that is able to exchange data with other hosts. Usually, an interface is a hardware device, but it might also be a pure software device, like the loopback interface. ... 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 ... 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...

Tài liệu Linux Device Drivers-Chapter 2 : Building and Running Modules pptx

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... implementations. For example, the video-for -linux set of drivers is split into a generic module that exports symbols used by lower-level device drivers for specific hardware. According to your ... new device, it will be able to avoid probing those ports that are already in use by other drivers. ISA probing is in fact a risky task, and several drivers distributed with the official Linux ... concurrency in kernel programming. Naturally, Linux systems run multiple processes, more than one of which can be trying several versions of modutils returned a " ;Device busy" message...

Tài liệu Linux Device Drivers-Chapter 3: Char Drivers docx

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... "methods," using object-oriented programming terminology to denote actions declared by an object to act on itself. This is the first sign of object-oriented programming we see in the Linux kernel, ... information from /proc/devices in order to create the files in /dev. the provided interface. In scull, one semaphore is allocated for each device, in the Scull_Dev structure. Since the devices are entirely ... of setting up the devices. for (i=0; i < scull_nr_devs; i++) { scull_devices[i].quantum = scull_quantum; scull_devices[i].qset = scull_qset; sema_init(&scull_devices[i].sem, 1);...

Tài liệu Linux Device Drivers-Chapter 4 : Debugging Techniques pptx

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... /proc is heavily used in the Linux system. Many utilities on a modern Linux distribution, such as ps, top, and uptime, get their information from /proc. Some device drivers also export information ... } 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. ... the /procfilesystem and using the ioctl driver method. You may use devfs as an alternative to /proc, but /proc is an easier tool to use for information retrieval. Using the /proc Filesystem...

Tài liệu Linux Device Drivers-Chapter 5 : Enhanced Char Driver Operations pptx

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... hand, if you did, you wouldn't benefit from using the bitfields. The header < ;linux/ kd.h> is an example of this old-fashioned approach, using 16-bit scalar values to define the ioctl ... 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. For ... cannot change the baud rate by writing to the device. That is what ioctl is for: controlling the I/O channel. Another important feature of real devices (unlike scull) is that data being read...

Tài liệu Linux Device Drivers-Chapter 6 : Flow of Time pptx

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... gettime: 846157215.942465 xtime: 846157215.941188 jiffies: 1308095 Delaying Execution Device drivers often need to delay the execution of a particular piece of code for a period of time ... according to the value of HZ, which is an architecture-dependent value defined in < ;linux/ param.h>. Current Linux versions define HZ to be 100 for most platforms, but some platforms use 1024, ... value of HZ for those who want systems with a different clock interrupt frequency. Some people using Linux for hard real-time tasks have been known to raise the value of HZ to get better response...

Tài liệu Linux Device Drivers-Chapter 7 : Getting Hold of Memory doc

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... cache. Device drivers normally do not exhibit the sort of memory behavior that justifies using a lookaside cache, but there can be exceptions; the USB and ISDN drivers in Linux 2.4 use caches. Linux ... for ISA devices. Backward Compatibility The Linux memory management subsystem has changed dramatically since the 2.0 kernel came out. Happily, however, the changes to its programming interface ... GFP_KERNEL and GFP_ATOMIC, although those two cover most of the needs of device drivers. All the flags are defined in < ;linux/ mm.h>: individual flags are prefixed with a double underscore,...

Tài liệu Linux Device Drivers-Chapter 8 :Hardware Management docx

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... with scull and similar toys is a good introduction to the software interface of a Linux device driver, implementing a real device requires hardware. The driver is the abstraction layer between ... the platforms and the kernel versions that lack them. Using I/O Ports I/O ports are the means by which drivers communicate with many devices out there at least part of the time. This section ... ports are: #include < ;linux/ ioport.h> can be either hardwired in the device or assigned by system firmware at boot time. The former is true, for example, of ISA devices, whose addresses...

Tài liệu Linux Device Drivers-Chapter 9 :Interrupt Handling Although doc

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... :Interrupt Handling Although some devices can be controlled using nothing but their I/O regions, most real-world devices are a bit more complicated than that. Devices have to deal with the external ... long as you don't use the two devices at the same time. It is quite common for users to load the module for a special device at system boot, even if the device is rarely used. A data acquisition ... up with more devices in your computer than there are interrupts. If a module requests an IRQ at initialization, it prevents any other driver from using the interrupt, even if the device holding...

Tài liệu Linux Device Drivers-Chapter 10 :Judicious Use of Data Types doc

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... Size to Data Items expression interface- specific to refer to a type defined by a library in order to provide an interface to a specific data structure. Even when no interface- specific type is ... Standard C Types Although most programmers are accustomed to freely using standard types like int and long, writing device drivers requires some care to avoid typing conflicts and obscure bugs. ... portability issues. Modern versions of the Linux kernel are highly portable, running on several very different architectures. Given the multiplatform nature of Linux, drivers intended for serious use...

Tài liệu Linux Device Drivers-Chapter 11 : kmod and Advanced docx

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... of the vmlinux file looks the same as before.  The public symbol table is built using the versioned names, and this is what appears in /proc/ksyms.  The module must be compiled using the ... #include < ;linux/ config.h> CONFIG_MODVERSIONS This macro is defined only if the current kernel has been compiled to support versioned symbols. #ifdef MODVERSIONS #include < ;linux/ modversions.h> ... This ability to request additional modules when they are needed is particularly useful for drivers using module stacking. The idea behind kmod is simple, yet effective. Whenever the kernel tries...