developing linux device drivers using libusb api

... 1 :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 ... 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...

Ngày tải lên: 24/12/2013, 01:17

... 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 ... not belong to any of the classes listed in "Classes of Devices and Modules" in Chapter 1, "An Introduction to Device Drivers& quot;. The sample driver shown in this chapter is called...

Ngày tải lên: 24/12/2013, 01:17

... 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); ... Allocation of Major Numbers Some major device numbers are statically assigned to the most common devices. A list of those devices can be found in Documentation/devices.txt within the kernel source ... actually knows the name of the device being opened, just the device number and users can play on this indifference to names by aliasing new names to a single device for their own convenience....

Ngày tải lên: 24/12/2013, 01:17

... /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. ... 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...

Ngày tải lên: 24/12/2013, 01:17

... 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...

Ngày tải lên: 24/12/2013, 01:17

... 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...

Ngày tải lên: 24/12/2013, 01:17

... 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 ... 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, ... kernel, memory can be allocated at boot time using these functions. The facility can only be used by drivers directly linked in the kernel image. the Linux kernel. The module is described in...

Ngày tải lên: 24/12/2013, 01:17

... well. A section of these 512 megabytes is reserved for peripheral devices, and drivers can access their I/O memory directly by using the noncached address range. Other platforms have other means ... 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...

Ngày tải lên: 24/12/2013, 01:17

... 34936135 IO-APIC-edge timer 1: 224407 226473 IO-APIC-edge keyboard 2: 0 0 XT-PIC cascade 5: 5636751 5636666 IO-APIC-level eth0 9: 0 0 IO-APIC-level acpi 10: 565910 565269 IO-APIC-level ... :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...

Ngày tải lên: 24/12/2013, 01:17

... 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 ... or warnings because the format It's important to remember that these types are Linux specific, and using them hinders porting software to other Unix flavors. Systems with recent compilers...

Ngày tải lên: 24/12/2013, 01:17

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