note 4 drivers

[Tutorial on industrial serial port and network software communication platform (SuperIO)] 4. Develop device drivers and network software superioSuperIO-related information download: http://pan.baidu.com/s/1pJ7lZWf1.1 Development Preparation Copy all files in the "Development Kit" to the "bin" directory of the project, or a dedicated generated directory under the project. The Development Kit files include:

to the ISA bus with a compatible interface connector Designed for jumper-free devices 32-bit address and data cable, multi-master DMA, and shared disconnection VLB VLB (VESA local BUS,VESA partial bus) interface bus, which extends the ISA connector by adding a third vertical slot SBus has been around for a long time, with quite a high level of design Although only SPARC computers use the bus, it is intended to be proc

stopped:1; Indicates whether the TTY device has stopped unsigned char hw_stopped:1 Indicates whether the TTY device hardware has stopped unsigned char low_latency:1 Indicates if the TTY device is a slow device unsigned char closing:1 Indicates whether the TTY device is shutting down the port struct Tty_driver driver; Control the current t

: = hello.clocal_module: = Hello.defaultinclude $ (build_shared_library)Note that Local_module's definition rules, followed by default,hello.default, ensure that our modules can always be loaded into the hard-like abstraction layer. Five. Compiling:[email protected]:~/android$ mmm Hardware/libhardware/modules/hello After the compilation is successful, you can see the hello.default.so file in the OUT/TARGET/PRODUCT/GENERIC/SYSTEM/LIB/HW directory. Six

describes how an Ethernet transceiver is connected to a network controller Int (*mdio_read) (struct net_device *dev, int phy_id, int location); void (*mdio_write) (struct net_device *dev, int phy_id, int location, int val); Drivers/net/mii.c Ethtool Support Ethtool is a tool for system administrators to control network interfaces Use Ethtool to control many interface parameters inc

atomic items that must be transmitted, and the direction of the transmission void Set_dma_mode (unsigned int channel, char mode); Mode Dma_mode_read Dma_mode_write Dma_mode_cascade Release control of the bus void set_dma_addr (unsigned int channel, unsigned int addr); void Set_dma_count (unsigned int channel, unsigne

(in kernel file include/linux/platform_device.h, the platform_device struct is defined)To enroll a device:1. Register the platform device structure body platform_device s3c_device_leds_ctl in the kernel file arch/arm/mach-exynos/mach-itop4412.cYou need to define name, ID, and so on. In Platform_device *smdk4x12_device[] __initdata you need to define the S3C_DEVICE_LEDS_CTL2. Ensure that the macro definition is defined in. config3. Recompile(in kernel file include/linux/platform_device.h, the int

Assuming that the transfer data between the hardware and the driver management is delayed for some reason, the driver author should implement buffering Data buffers help to separate the delivery and reception of data from the system call write and read, thereby improving the overall performance of the system A good buffering mechanism requires interrupt-driven I/O To properly interrupt-driven transmission data, the hardware should be able to generate interrupts acco

preprocessing typedef int (PREP_RQ_FN) (request_queue_t *queue, struct request *req); The function can return one of the following values Blkprep_ok Blkprep_kill Blkprep_defer void Blk_queue_prep_rq (request_queue_t *queue, Prep_rq_fn *func); Flag Command Queue Hardware that has multiple active requests at the same time typically supports some form of tagged

DMA controller unsigned long claim_dma_lock (); The information that must be loaded into the controller consists of three parts: the address of the RAM, the number of atomic items that must be transmitted, and the direction of the transmission void Set_dma_mode (unsigned int channel, char mode); Mode Dma_mode_read Dma_mode_write Dma_mode_cascade Rel

Clock management for linux Device Drivers (4) ---- it turns out to be a child When I was a child, I saw a TV series called "Little Dragon man". You don't have to mention it. It's actually very inspirational. To find my mother, it's a great TV series, what are the children watching? Xuanyuan sword, god of every day, magic, illusion, and flashy stuff. Apart from commercial value, what kind of stuff can be use

Skb_release_data function has 0xc4 so large, and oops occurs at 0x74 place. So let's take a look at where the Skb_release_data starts:#grep Skb_release_data./system.mapC0282AF4 T Skb_release_dataSo we know that when the system error occurs, the program pointer is c0282af4+0x74=c0282b68(2) Then use GDB to view the GDB./vmlinux (executed under the Linux directory) and enter debug mode.gdb$ b *0xc0282b68Breakpoint 1 at 0xc0282b68:file NET/CORE/SKBUFF.C, line312This is to tell us in which file, in

buffers help to separate the delivery and reception of data from the system call write and read, thereby improving the overall performance of the system A good buffering mechanism requires interrupt-driven I/O To properly interrupt-driven data transfer, the hardware should be able to generate interrupts according to the following semantics For input, the device interrupts the processor when new data has arrived and the processor is ready to receive it For outp

kernel unsigned long copy_to_user (void __user *to, const void * from, unsigned long count) unsigned long copy_from_user (void *to, const void __user *from, unsigned long count); Any function that accesses user space must be reentrant, must be able to execute concurrently with other driver functions, and must be in a state that can legally hibernate Read method If the return value is equal to the count parameter for passing the read

No_llseek Access control for device files Exclusive equipment The most blunt method of access control is to allow only one process to open the device at a time Restrict access by only one user at a time Requires two data items An open count UID of the device owner Current->uid Current->euid Block Open alternative to Ebusy This is usually the

); Read-copy-update Read-copy-update (RCU) is also an advanced mutex mechanism. Rarely used in drivers Http://www.rdrop.com/users/paulmck/rclock/intro/rclock_intro.html Optimized for situations where reads are frequent and rarely written The protected resource should be accessed through a pointer When the data structure needs to be modified, the write thread replicates first,

when a per-cpu variable is created. Each processor in the system will have a unique copy of the variable does not need to be locked can be saved in a fast cache of the appropriate processor DEFI NE_PER_CPU (type, name); get_cpu_var (variable); put_cpu_var (variable); per_cpu (variable, int cpu_id); void *alloc_percpu (type); void *__alloc_percpu (size_t size, size_t align); per_cpu_ptr (vo

> define_per_cpu (type, name); get_cpu_var (variable); put_cpu_var (variable); per_cpu (variable, int cpu_id); void *alloc_percpu (type); void *__alloc_percpu (size_t size, size_t align); per_cpu_ptr (void *per_cpu_var, int cpu_id); Export_per_cpu_symbol (Per_cpu_var); EXPORT_PER_CPU_SYMBOL_GPL (Per_cpu_var); declare_per_cpu (type, name); Get a large buffer Obtai