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

... 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 ... /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 mkno...

Ngày tải lên: 24/12/2013, 01:17

... Chapter 5 : Enhanced Char Driver Operations In Chapter 3, " ;Char Drivers& quot;, we built a complete device driver that the user can write to and read from. But a real device usually offers ... same device. Different 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. Clon...

Ngày tải lên: 24/12/2013, 01:17

... 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 ... the open source nature of the Character devices A character (char) device is one that can be accessed as a stream of bytes (like a file); a char driver is in charge of implementin...

Ngày tải lên: 24/12/2013, 01:17

... to Device Drivers& quot;. #define MODULE #include < ;linux/ module.h> buffer-based graphics environments, where the X server acts only as a server based on a real kernel-space device ... users.  The most important devices can't be handled in user space, including, but not limited to, network interfaces and block devices. As you see, user-space drivers can't d...

Ngày tải lên: 24/12/2013, 01:17

... Time for an example. Here is a simple read_procimplementation for the scull device: int scull_read_procmem (char *buf, char **start, off_t offset, int count, int *eof, void *data) { int ... in its read implementation: char faulty_buf[1024]; ssize_t faulty_read (struct file *filp, char *buf, size_t count, loff_t *pos) { int ret, ret2; char stack_buf[4]; p...

Ngày tải lên: 24/12/2013, 01:17

... #include < ;linux/ delay.h> void udelay(unsigned long usecs); Chapter 6 : Flow of Time At this point, we know the basics of how to write a full-featured char module. Real-world drivers, however, ... available in Linux 2.0, sysdep.h fills the gap. Task Queues One feature many drivers need is the ability to schedule execution of some tasks at a later time without resorting t...

Ngày tải lên: 24/12/2013, 01:17

... that describes the allocation interface it offers to device drivers. The Zoran 36120 frame grabber driver, part of the 2.4 kernel (in drivers /char/ zr36120.c) uses the bigphysarea extension if ... 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 und...

Ngày tải lên: 24/12/2013, 01:17

... 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 software ... easy to use. I/O Ports and I/O Memory Every peripheral device is controlled by writing and reading its registers. Most of the time a device has several registers, and they are ac...

Ngày tải lên: 24/12/2013, 01:17

... :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 ... can explicitly be shared. So Linux supports shared interrupts and on all buses where it makes any sense, not just the PCI. Thus, suitably aware drivers for ISA devices can also share a...

Ngày tải lên: 24/12/2013, 01:17

... 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 ... demonstrated by running the program on different Linux computers: arch Size: char shor int long ptr long- long u8 u16 u32 u64 } The < ;linux/ list.h> file also defines a m...

Ngày tải lên: 24/12/2013, 01:17