using negative variables in other semantics

... deadline of 100 Hz (using clock_set_timer_deadline()) Memory Management The Mach layer is responsible for coordinating the use of physical memory in a machine independent manner, providing a ... main memory, and not to a destination in the backing store Therefore, to handle the read request, the driver needs to ensure that the user buffer is swapped into main memory and remains in main ... internals will be useful in understanding the concepts discussed in this book Having completed an introductory computer science or engineering course will be a helpful starting point Additionally, knowledge...

Ngày tải lên: 15/03/2014, 02:20

... type Interface Number Alternate Setting Number Number of endpoints in this intf Class code Subclass code Protocol code Interface string index /* Endpoint Descriptor */ 7, USB_DESCRIPTOR_ENDPOINT, ... defining USB_USE_MSD In addition, the MSD class firmware must know which endpoints have been selected in the descriptors to use as the MSD endpoints In this example, Endpoint was used for the in ... knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets Most likely, the person doing so is engaged in theft of intellectual...

Ngày tải lên: 11/01/2016, 16:48

... Allocating Additional Clusters 226 Managing Files 228 Obtaining File Information 228 Finding a File 231 Creating a Directory Entry 234 Finding an Available Entry 235 Creating a File 238 Deleting ... Ltd., to Rawin Rojvanit and Gurinder Singh of Microchip Technology, Inc., and to Alan Stern of the Rowland Institute at Harvard For their help in obtaining products used in the writing of the ... Microchip Technology Inc in the U.S.A and other countries Certain materials contained herein are reprinted with the permission of Microchip Technology Incorporated No further reprints or reproductions...

Ngày tải lên: 06/07/2014, 15:37

... knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets Most likely, the person doing so is engaged in theft of intellectual ... Microchip Technology Incorporated in the U.S.A and other countries SQTP is a service mark of Microchip Technology Incorporated in the U.S.A All other trademarks mentioned herein are property of ... driver Since each function in this layer must complete before the next operation can begin, Mass Storage transfer events are not used FIGURE 5: USB CONFIGURATION - MASS STORAGE DEFINING THE INTERFACE...

Ngày tải lên: 11/01/2016, 16:46

... thread that is executing inside the DLL at the time may be terminated and cause an exception in the calling applications To avoid this, thread counting must be implemented in most functions—especially ... transfers using USBDI transfer functions are limited to 8K of data per transfer, due to an internal limitation in Microsoft’s USB implementation If you are porting USB client drivers from Microsoft Windows ... functions to interact with the device However, because the Device Manager is not involved in the loading and unloading of USB device driver s, any driver that exposes the stream interface functions...

Ngày tải lên: 07/10/2013, 00:20

... In these cases, the GroupX_ID values may be combined to generate other combinations The precedence for such combinations is as follows, in descending order: Group1_ID\Default\Default Group1_ID\Group2_ID\Default ... without prompting a user In some cases it may be necessary to specify the precedence order to a greater level of detail; for example, combining vendor- and device-class specifiers In these cases, ... USBInstallDriver should create an appropriate subkey for the driver by calling the RegisterClientSettings function so the next time that the USB device...

Ngày tải lên: 07/10/2013, 00:20

... SW manages an interface Buffers Interface x No USB Format Pipe Bundle to an interface Unspecified Host Cntrl Endpoint Zero Default Pipe to Endpoint Zero Data Per Endpoint USB Bus Interface SIE ... Controller –Input and Output FIFOs for Control Endpoint –Input or Output FIFO for other Endpoints ? DMA Controller ? Internal Bus ? Serial Interface Engine ? Output Pads 15 Example of USB Controller ... USBIoctl() ? Callback Message Queue 30 15 USBInit() and USBDelete() USBInit() USBDelete() ? USBInit() - Initialize USB Driver USBInit() –Installs driver in IO system –Creates or acquires OS resources...

Ngày tải lên: 13/12/2013, 00:15

... Writing device drivers in Linux: A brief tutorial #include #include #include #include #include #include #include #include #include #include #include #include ... = /* Necessary includes for drivers */ #include #include #include #include /* printk() */ #include ... #include /* everything */ #include /* error codes */ #include /* size_t */ #include #include /* O_ACCMODE */ #include...

Ngày tải lên: 23/10/2013, 22:15

... Writing device drivers in Linux: A brief tutorial #include #include #include #include #include #include #include #include #include #include #include #include ... = /* Necessary includes for drivers */ #include #include #include #include /* printk() */ #include ... #include /* everything */ #include /* error codes */ #include /* size_t */ #include #include /* O_ACCMODE */ #include...

Ngày tải lên: 13/12/2013, 11:15

... license, you can find it in several places in your system, including the directory /usr/src/linux, as a file called COPYING Third-party and custom modules are not part of the Linux kernel, and ... the world of kernel programming Chapter 2, "Building and Running Modules" introduces modularization, explaining the secrets of the art and showing the code for running modules Chapter 3, "Char ... device, like the loopback interface A network interface is in charge of sending and receiving data packets, driven by the network subsystem of the kernel, without knowing how individual transactions...

Ngày tải lên: 24/12/2013, 01:17

... itself may be used in kernel modules Anything related to the kernel is declared in headers found in include/linux and include/asm inside the kernel sources (usually found in /usr/src/linux) Older distributions ... naming the module initialization and cleanup routines; using this facility is the preferred programming style Consider an example If your module names its initialization routine my_init (instead ... performs a single task from beginning to end, a module registers itself in order to serve future requests, and its "main" function terminates immediately In other words, the task of the function init_module...

Ngày tải lên: 24/12/2013, 01:17

... about kdev_t is confined in , which is mostly comments The header makes instructive reading if you're interested in the reasoning behind the code There's no need to include the header ... skills are introduced in Chapter 8, "Hardware Management", and in Chapter 9, "Interrupt Handling" Therefore, you can skip this section if you're not interested in understanding the inner workings of ... again in other contexts later in the book The file Structure struct file, defined in , is the second most important data structure used in device drivers Note that a file has nothing...

Ngày tải lên: 24/12/2013, 01:17

... without a logging process, while minimizing memory waste by overwriting old data should nobody read it Another feature of the Linux approach to messaging is that printk can be invoked from anywhere, ... you need the information, instead of continually producing data In fact, every Unix system provides many tools for obtaining system information: ps, netstat, vmstat, and so on Two main techniques ... splitting data into fragments smaller than a page Another interesting advantage of the ioctlapproach is that informationretrieval commands can be left in the driver even when debugging would otherwise...

Ngày tải lên: 24/12/2013, 01:17

... look like The new way to define numbers uses four bitfields, which have the following meanings Any new symbols we introduce in the following list are defined in type The magic ... it were a single instruction, without the possibility of the processor being interrupted and something happening in between (such as somebody else's code running) The explicit ordinal number ... reply for an incorrect ioctl command Things have changed, but fcntl remains in the name of backward compatibility Using the ioctl Argument Another point we need to cover before looking at the ioctl...

Ngày tải lên: 24/12/2013, 01:17

... did not exist in Linux 2.0 Instead, a global variable intr_count kept track of the number of interrupt handlers running Querying intr_count is semantically the same as calling in_ interrupt, so ... confined to the jiq_print_tq function, which executes at each run through the queue being used The printing function is not interesting and is not worth showing here; instead, let's look at the initialization ... hardware interrupt happens (which is discussed in detail in Chapter 9, "Interrupt Handling") In fact, task queues are often run as the result of a "software interrupt.'' When running in interrupt...

Ngày tải lên: 24/12/2013, 01:17

... best function to use If you are going to resort to grabbing memory at boot time, you must modify init/main.c in the kernel sources You'll find more about main.c in Chapter 16, "Physical Layout ... kmem_cache_destroy; a failure indicates some sort of memory leak within the module (since some of the objects have been dropped) One side benefit to using lookaside caches is that the kernel maintains statistics ... returned by ioremap as if they were pointers to memory Rather, you should always use readb and the other I/O functions introduced in "Using I/O Memory", in Chapter 8, "Hardware Management" This...

Ngày tải lên: 24/12/2013, 01:17

... so-called string instructions, and they perform the task more quickly than a Clanguage loop can The following macros implement the concept of string I/O by either using a single machine instruction ... I/O operation, you can use the six pausing counterparts of the functions introduced in the previous entry; these pausing functions have names ending in _p void insb(unsigned port, void *addr, unsigned ... seen on output pins is changed according to the individual bits being written When you read a value from the input location, the current logic level seen on input pins is returned as individual bit...

Ngày tải lên: 24/12/2013, 01:17

... that the probing functions we are going to introduce depend on the jumper between pin and 10 being in place, and you'll need it to experiment with probing using our code Installing an Interrupt ... just by disabling interrupts; some sort of locking mechanism must be used Functions such as spin_lock_irqsave (covered in "Using Spinlocks", later in this chapter) provide locking and interrupt control ... of an interrupt handler It, in turn, calls short_incr_bp, which is defined as follows: static inline void short_incr_bp(volatile unsigned long *index, int delta) { unsigned long new = *index...

Ngày tải lên: 24/12/2013, 01:17

... find this type of error Other Portability Issues In addition to data typing, there are a few other software issues to keep in mind when writing a driver if you want it to be portable across Linux ... will happen in future kernels Whenever you calculate time intervals using jiffies, scale your times using HZ (the number of timer interrupts per second) For example, to check against a timeout ... describing one entry in the list To use the Linux list facility in your code, you need only embed a list_head inside the structures that make up the list If your driver maintains a list of things...

Ngày tải lên: 24/12/2013, 01:17

... inter_module_get_request("ime_string", "inter"); if (ime_string) printk(KERN_INFO "master: got ime_string '%s'\n", ime_string); else printk(KERN_INFO "master: inter_module_get failed"); ime_func = inter_module_get("ime_function"); ... appear in the object files as undefined symbols  The loading program (insmod) matches the undefined symbols in the module with the public symbols in the kernel, thus using the version information ... inter_module_get_request to cause the inter module to be loaded and to obtain the two pointers The string is simply printed, and the function pointer is used to make a call from master into inter...

Ngày tải lên: 21/01/2014, 07:20