linux spi example

blog by Http://blog.csdn.net/droidphone Original, reproduced please indicate the source, thank you!/*****************************************************************************************************/Defining controller Devices The SPI controller follows the Linux device model framework, so that an SPI controller corresponds to one device structure in th

Through the introduction of the previous article, we know that the SPI Universal interface layer is used to connect the specific SPI device protocol driver and SPI Controller driver, the general interface layer in addition to the protocol driver and controller driver to provide a series of standard interface APIs, but also for these interface API defines the corr

://blog.csdn.net/droidphone Original, reproduced please indicate the source, thank you./*****************************************************************************************************/defining a controller device The SPI controller follows the Linux device model framework, so an SPI controller corresponds to a device structure in the code, and for embedded

below it, and the worker threads will process the message requests one at a time according to the FIFO principle, and after each message transfer, the corresponding SPI_ The complete callback function of the message structure is invoked to notify the Protocol driver of preparing the next frame of data. This is the queue of spi_message. When a worker thread wakes up, the relationship between Spi_master, Spi_message, and Spi_transfer can be described in the following illustration: queues and

. This is why the sck clock line exists and the sck provides the clock pulse, miso and MoSi complete data transmission based on this pulse. SPI supports 4-32bits serial data transmission and MSB and LSB. You need to reset the size of the SPI master when the size of the device changes during each data transmission. 2 Overall Linux

pending spi_message structures under Master, and the worker thread will process each of these message requests on a first-in, one-out basis, after each message transfer is complete, corresponding to the Spi_ The complete callback function of the message structure is called to notify the Protocol driver to prepare the next frame of data. This is the spi_message of the queue. When a worker thread wakes up, the relationship between Spi_master, Spi_message, and spi_transfer can be used to describe:

Linux Device Driver inquiry 1st days ---- spi Driver (1), 1st days ---- spi This document allows reprinting. Please indicate the source:Http://blog.csdn.net/fulinus The Linux kernel code is too big, and a small module will make you feel helpless. This afternoon, I am determined to take a good look at the

I. Overview Developing Drivers Based on subsystems is a common practice in Linux kernel. I have previously written about driver development based on the I2C subsystem. This article introduces another common bus SPI development method. The development of the SPI subsystem has many similarities with I2C, so you can compare and learn. This topic is divided into two

Linux Kernel SPI subsystem architecture analysis (clear) There are two types of equipment on the SPI bus: one is the main control end, which is usually used as a sub-module of the SoC system. For example, many embedded mpus usually contain SPI modules. One is the controlled

other subsystems of the kernel, for example, interacting with the MTD layer to implement the SPI interface's storage device as a file system. Interacting with the TTY subsystem, the SPI device is implemented as a TTY device, interacting with the network subsystem to implement an SPI device as a network device, and so

SPI is a "serial peripheral Interface" abbreviation, is a four-wire synchronous serial communication interface, used to connect microcontrollers, sensors, storage devices, SPI equipment divided into the main equipment and two from the device, the four lines for communication and control are: The CS chip chooses the signal SCK the clock signal MISO The main equipment The data input, from the device's data ou

SPI is a "serial peripheral Interface" abbreviation, is a four-wire synchronous serial communication interface, used to connect microcontrollers, sensors, storage devices, SPI equipment divided into the main equipment and two from the device, the four lines for communication and control are: The CS chip chooses the signal SCK the clock signal MISO The main equipment The data input, from the device's data ou

SPI is "Serial peripheral Interface" abbreviation, is a four-wire synchronous serial communication interface, used to connect microcontrollers, sensors, storage devices, SPI device sub-primary device and two from the device, for communication and control of the four lines are: CS Chip Selection Signal SCK Clock Signal Miso the data input from the main device, the data output pin from the de

========================================================== ====Author: yuanlulu Http://blog.csdn.net/yuanlulu No copyright, but please keep this statement for reprinting========================================================== ==== The relationship between spi_master/spi_device and spi_driver. Important data structures: ~~~~~~~~~~The topic of the SPI controller is spi_master. Although you do not need to write your own

{ return numbera + Numberb; }}SPI implementation class for the interface: DivisionoperationimplImport co.solinx.demo.api.ioperation;/** * Created by LX on 2015/3/8. */public class Divisionoperationimpl implements IOperation { @Override public int operation (int numbera, int Numberb) { return numbera/numberb; }}meta-inf/services files in the directory:File name: co.solinx.demo.api.IOperation, Content: Co.solinx.demo.spi.Divis

Now that we know the protocol, we can start to look at the SPI driver code in Linux kenerl. There are many struct in the code, so let's take a look at the main struct first, in this way, we can better understand the driver. Mainly include/Linux/SPI. h The first is the communication interface between the

;/*** Created by LX on 2015/3/8.*/publicclassPlusOperationImplimplementsIOperation { @Overridepublicintoperation(intnumberA,intnumberB) {returnnumberA + numberB;}} SPI implementation class for the interface: Divisionoperationimpl 123456789101112 importco.solinx.demo.api.IOperation;/*** Created by LX on 2015/3/8.*/publicclassDivisionOperationImplimplementsIOperation { @Overridepublicintoperation(intnumberA,intnumberB) {returnnu

Java SPI mechanism and simple example, callback PI Mechanism I. SPIMechanism Here we will first describe the concept of SPI. In English, a single SPI Service Provider Interface can be literally understood as a Service Provider Interface, just as a Service Provider Interface can be understood from the

Break;1509}1510}15111512 / * Device speed * /1513rc = Of_property_read_u32 (NC,"Spi-max-frequency", value);1514 if(RC) {1515Dev_err (master->dev,"%s have no valid ' spi-max-frequency ' property (%d)\ n",1516Nc->full_name, RC);1517 GotoErr_out;1518}1519Spi->max_speed_hz = value;15201521 / * Store A pointer to the node in the device structure * /1522Of_node_get (NC);1523Spi->

*mtd, loff_t to, size_t len,size_t *retlen, const U_char *buf) {struct m25p *flas h = mtd_to_m25p (MTD); U32 page_offset, page_size;struct spi_transfer t[2];//This structure and the structure of the following line is very important to see the above diagram to see the struct SPI_ Message M;debug (Mtd_debug_level2, "%s:%s%s 0x%08x, Len%zd\n", Dev_name (flash->spi->dev), __func__, "to", ( U32) to, len); *retlen = 0;/* Sanity checks */if (!len) return (0