Tài liệu Linux Device Drivers-Chapter 15 :Overview of Peripheral Buses pdf

... break; Chapter 15 :Overview of Peripheral Buses Whereas Chapter 8, "Hardware Management" introduced the lowest levels of hardware control, this chapter provides an overview of the higher-level ... bits first. It is possible for one device to offer both 32-bit regions and 64-bit regions. PCI I/O resources in Linux 2.4 In Linux 2.4, the I/O regions of PCI...

Ngày tải lên: 21/01/2014, 07:20

... to schedule execution of some tasks at a later time without resorting to interrupts. Linux offers three different interfaces for this purpose: task queues, tasklets (as of kernel 2.3.43), and ... task queues are often run as the result of a "software interrupt.'' When running in interrupt mode (or interrupt time) in this way, your code is subject to a number of c...

Ngày tải lên: 24/12/2013, 01:17

... Chapter 7 : Getting Hold of Memory Thus far, we have used kmalloc and kfree for the allocation and freeing of memory. The Linux kernel offers a richer set of memory allocation primitives, ... flags can be used in place of or in addition to 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...

Ngày tải lên: 24/12/2013, 01:17

... bunch of #ifdef __LITTLE_ENDIAN conditionals, but there is a better way. The Linux kernel defines a set of macros that handle conversions between the processor's byte ordering and that of ... misc-progs directory of the sample code, and an equivalent kdataalign module is part of misc-modules. This is the output of the program on several platforms and the output of the...

Ngày tải lên: 24/12/2013, 01:17

... Although not trivial, proficient use of Unix tools is outside of the scope of this book. In our opinion, acquiring a bit of a knowledge base before sitting down in front of your preferred shell ... describing them all would make no sense. Drivers Current Linux kernels support a huge number of devices. Device drivers account for half of the size of the source tree (a...

Ngày tải lên: 21/01/2014, 07:20

... 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 the hardware ... class of devices is that of SCSI[1] drivers. Although every peripheral connected to the SCSI bus appears in /dev as either a char device or a block device, the int...

Ngày tải lên: 24/12/2013, 01:17

... privileged user (this is one of the problems being solved by the frame buffer device driver running in kernel space). But the user-space approach to device driving has a number of drawbacks. The most ... That is, the module will not belong to any of the classes listed in "Classes of Devices and Modules" in Chapter 1, "An Introduction to Device Drivers"....

Ngày tải lên: 24/12/2013, 01:17

... of behavior is interesting to look at anyway, because some devices require types of management like the ones shown in these scull variations as part of their mechanism. Each of the scull devices ... /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...

Ngày tải lên: 24/12/2013, 01:17

... number of bytes of data actually placed in the page buffer, just like the read implementation does for other files. Other output values are *eof and *start. eof is a simple flag, but the use of ... scull_get_info(char *buf, char **start, off_t offset, int len, int unused) { int eof = 0; return scull_read_procmem (buf, start, offset, len, &eof, NULL); } struct proc_di...

Ngày tải lên: 24/12/2013, 01:17

... copies of the device depending on the process opening it. Clearly this is possible only if the device is not bound to a hardware object; scull is an example of such a "software'' device. ... 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 provid...

Ngày tải lên: 24/12/2013, 01:17