CN112286858A - Linux system I2C driver method based on signal - Google Patents
Linux system I2C driver method based on signal Download PDFInfo
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- CN112286858A CN112286858A CN202011195845.2A CN202011195845A CN112286858A CN 112286858 A CN112286858 A CN 112286858A CN 202011195845 A CN202011195845 A CN 202011195845A CN 112286858 A CN112286858 A CN 112286858A
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- 230000006870 function Effects 0.000 claims description 41
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- 230000008569 process Effects 0.000 claims description 15
- 230000009131 signaling function Effects 0.000 claims description 8
- 230000005540 biological transmission Effects 0.000 claims description 5
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- G06F13/38—Information transfer, e.g. on bus
- G06F13/42—Bus transfer protocol, e.g. handshake; Synchronisation
- G06F13/4282—Bus transfer protocol, e.g. handshake; Synchronisation on a serial bus, e.g. I2C bus, SPI bus
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Abstract
The invention belongs to the technical field of embedded drivers, and relates to a signal-based linux system I2C driver method, which comprises an asynchronous notification mechanism for preparing a start-up file, an asynchronous notification interface unit for designing a driver, a signal installation unit and a function test unit for designing the driver; the invention applies a signal mechanism to the driving program and informs the user program to read data.
Description
Technical Field
The invention belongs to the technical field of embedded driving, and particularly relates to a signal-based Linux system I2C driver method.
Background
With the rapid development of electronic technology, embedded systems based on microprocessors have rapidly become widespread. The embedded system has two working modes, the first one is based on a single chip microcomputer, the hardware resource of the system is limited, the software is simple, and the system does not contain an operating system; the second one can run an operating system, and greatly utilizes rich resources of a PC, and in an embedded operating system, Linux is an open source code, is developed most rapidly and is applied most widely. The I2C bus transfers information between devices connected to the bus through a serial data line (SDA) and a Serial Clock Line (SCL), each device is identified according to an address, the I2C has two working modes, namely a master-sending master-receiving mode and a slave-sending slave-receiving mode, the slave-receiving slave-sending mode is master-sending of slave equipment, and the return time of the equipment is uncertain, so that an interrupt mode is adopted. The Linux driver only realizes the functions of main transmission, main transmission and main reception and only realizes half of I2C.
In the I2C bus driving process, Linux needs a user to actively operate a device file, and a user program cannot predict the arrival time of device data, so that the software running efficiency is reduced, the real-time performance is poor, meanwhile, a hardware interrupt mechanism cannot be well utilized to process an emergency, and only a function is utilized to periodically query whether a device is readable, so that the efficiency is not high. This is a drawback in the prior art.
In view of the above, it is desirable to provide a signal-based Linux system I2C driver method to solve the problems in the prior art.
Disclosure of Invention
The invention aims to provide a method for designing a signal-based Linux system I2C driver, aiming at the defects of low efficiency and poor real-time performance of timing query of device data based on a query mode in a Linux system I2C driver in the prior art, and solving the technical problem by applying a signal mechanism to the driver and informing a user program of reading data.
In order to achieve the purpose, the invention provides the following technical scheme: a signal-based linux system I2C driver method, comprising the steps of:
s1: preparing an asynchronous notification mechanism for an enabled file;
s2: designing a driven asynchronous notification interface unit;
s3: designing a signal installation unit;
s4: and designing a functional test unit of the driver.
Preferably, in step S1: the asynchronous notification mechanism for preparing the enabled file modifies a standard I2C driver under a Linux system, and comprises the steps of adding macro definition USE _ ASYNC in an I2c _ adapter data structure in an I2c.h file, and realizing the definition of variables I2c _ event and queue; adding macro definition USE _ ASYNC in an i2c _ dev _ fos data structure in an i2c _ dev.c file to realize fasync, i2cdev _ fasync and newly adding a static function i2cdev _ fasync;
the i2c _ xxx module sending the SIGIO signal includes that the i2c _ xxx _ add _ bus function under the i2c _ algo _ xxx module increases by i2c _ xxx _ ap ═ adap; in the interrupt function iic _ xxx _ handle of the i2c _ xxx module, the following statement is added before the data processing is finished and ready to return,
#ifdef USE_ASYNC
if(i2c_xxx_ap->i2c_event)
kill_fasync(&(i2c_xxx_ap->i2c_event),SIGIO,POLL_IN)。
preferably, in step S2: the design uses a driven asynchronous notification interface unit, an interface method corresponding to the fcntl system call of the user program is set, and when the process uses the fcntl system call to execute the F _ SETOWN command, the process ID number of the owner process is stored in file- > F _ winner; setting a FASYNC mark in the equipment after the fcntl command F _ SETFL is completed, wherein the equipment can request to send a SIGIO signal when new data arrives, and the SIGIO signal is stored in a process in file- > F _ inner;
setting a semaphore host, taking a file descriptor and adding an asynchronous reading mark in a user program; the user program is conditioned for using an asynchronous notification interface.
Preferably, in step S3: the signal installation unit initializes semaphore, installs signal function by using sign (), supports signal transmission information and can transmit file handle.
Preferably, the sigaction () function sets three parameters, the first parameter is the value of the signal, the second parameter is a pointer pointing to the sigainfo _ t structure, and the parameters include the processing of the specified signal, the information of signal transmission, and which functions should be masked during the execution of the signal processing function; the object pointed by the third parameter oldact is used for saving the original processing of the corresponding signal; setting a SA _ SIGINFO flag bit in the structure action to indicate that parameters attached to a signal can be transmitted to a signal processing function, wherein the flag bit SA _ SIGINFO is regarded as a switch for judging whether the signal transmits the parameters or not; the processing function is specified by sa _ gesture in the gesture structure, which specifies which signals should be blocked during execution of the signal processing routine.
Preferably, in step S4, the functional test unit of the driver is configured with two I2C devices fd, fd1 to test the application of signals in the driver; the function test unit comprises a main i2c file initialization unit; i2c-bit file initialization unit; an initialization unit of the signal; setting a signal function unit; the main function compiling unit is used for ensuring that the driving program of the Linux system I2C based on the signal runs normally;
the main I2c file initialization unit comprises setting I2C bus controller clock frequency; setting a master sending and receiving and a slave sending and receiving, and setting a seven-bit address; the i2c-bit file initialization unit sets a seven-bit address;
the initialization unit of the signal comprises a signal function setting unit, a semaphore host, a file descriptor fetching unit, an asynchronous reading mark adding unit, an asynchronous reading semaphore setting unit and a keyboard reset unit;
the signal setting function unit comprises the steps of acquiring an SIGIO signal, transmitting a main i2c file handle and transmitting an i2c-bit file handle;
and the main function writing unit judges the states of fd and fd1 and executes corresponding operation.
Preferably, i2c _ init () defines a structure sign variable, and sets the signal processing function name myread:
action.sa_sigaction＝myread；
and (3) transmitting additional information:
action.sa_flags＝SA_SIGINFO；
sigaction () function install signal:
sigaction(SIGIO,&action,NULL)；
the myread code is as follows:
firstly, judging whether the signal type is SIGIO through a sign, then transmitting a file descriptor through a si _ fd member of a siginfo _ t structure, automatically distributing by a system when a device is opened by an open method, and finally entering a processing module, wherein i2c _ readevent (), i2c _ readkb () are respectively processed, and codes are as follows:
thus, the I2C bus driver is signal processed to meet the requirement of real-time interrupt basically.
The invention has the advantages that the I2C driver based on asynchronous notification well utilizes a hardware interrupt mechanism to process emergency events, the main transmission and the main reception of the I2c bus are set without interruption, and the auxiliary transmission and the auxiliary reception of the I2c bus are completely carried out in the interruption as long as the simple return is carried out, so that the real-time processing of the interruption is realized, meanwhile, a plurality of drivers work in an asynchronous notification mode without mutual interference, the data processing efficiency is improved, and the invention has more advantages when the data volume is large; the Linux system I2C driving program based on the signal has novel thought, so that the user program calling method in the Linux system is simpler and more practical than the traditional method, and the programming efficiency is improved; the method can be popularized to the compiling of other driving programs, the Linux code is optimized, and the efficiency is improved. In addition, the invention has reliable design principle, simple structure and very wide application prospect.
Therefore, compared with the prior art, the invention has substantial characteristics and remarkable progress, and the beneficial effects of the implementation are also obvious.
Drawings
FIG. 1 is a flowchart of a signal-based Linux system I2C driver method.
FIG. 2 is a schematic diagram of a hierarchy of I2C drivers of the Linux system.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings by way of specific examples, which are illustrative of the present invention and are not limited to the following embodiments.
As shown in FIG. 1, the present invention provides a signal-based Linux system I2C driver method, comprising the steps of:
a signal-based linux system I2C driver method, comprising the steps of:
s1: preparing an asynchronous notification mechanism for an enabled file;
s2: designing a driven asynchronous notification interface unit;
s3: designing a signal installation unit;
s4: and designing a functional test unit of the driver.
In this embodiment, the samsung ARM9 processor 2410 is taken as an example:
in the step S1: the asynchronous notification mechanism for preparing the enabled file modifies a standard I2C driver under a Linux system, and comprises the steps of adding macro definition USE _ ASYNC in an I2c _ adapter data structure in an I2c.h file, and realizing the definition of variables I2c _ event and queue; adding macro definition USE _ ASYNC in an i2c _ dev _ fos data structure in an i2c _ dev.c file to realize fasync, i2cdev _ fasync and newly adding a static function i2cdev _ fasync;
the i2c _ s3c2410 module sending the SIGIO signal includes the i2c _ s3c2410_ add _ bus function under the i2c _ algo _ s3c2410 module increasing i2c _ s3c2410_ ap to adap; in the interrupt function iic _ s3c2410_ handler of the i2c _ s3c2410 module, the following statement is added before the data processing is finished and ready to return,
#ifdef USE_ASYNC
if(i2c_s3c2410_ap->i2c_event)
kill_fasync(&(i2c_s3c2410_ap->i2c_event),SIGIO,POLL_IN)。
in the step S2: the design uses a driven asynchronous notification interface unit, an interface method corresponding to the fcntl system call of the user program is set, and when the process uses the fcntl system call to execute the F _ SETOWN command, the process ID number of the owner process is stored in file- > F _ winner; setting a FASYNC mark in the equipment after the fcntl command F _ SETFL is completed, wherein the equipment can request to send a SIGIO signal when new data arrives, and the SIGIO signal is stored in a process in file- > F _ inner; setting a semaphore host, taking a file descriptor and adding an asynchronous reading mark in a user program; the user program is conditioned for using an asynchronous notification interface.
In the step S3: the signal installation unit initializes semaphore, installs signal function by using sign (), supports signal transmission information and can transmit file handle. The sigaction () function sets three parameters, the first parameter is the value of the signal, the second parameter is a pointer pointing to the sigainfo _ t structure, and the functions which should be shielded in the execution process of the information signal processing function of the designated signal processing and signal transmission are included; the object pointed by the third parameter oldact is used for saving the original processing of the corresponding signal; setting a SA _ SIGINFO flag bit in the structure action to indicate that parameters attached to a signal can be transmitted to a signal processing function, wherein the flag bit SA _ SIGINFO is regarded as a switch for judging whether the signal transmits the parameters or not; the processing function is specified by sa _ gesture in the gesture structure, which specifies which signals should be blocked during execution of the signal processing routine.
In step S4, the functional test unit of the driver is configured with two I2C devices fd, fd1 to test the application of signals in the driver; the function test unit comprises a main i2c file initialization unit; i2c-bit file initialization unit; an initialization unit of the signal; setting a signal function unit; the main function compiling unit is used for ensuring that the driving program of the Linux system I2C based on the signal runs normally;
the main I2c file initialization unit comprises setting I2C bus controller clock frequency; setting a master sending and receiving and a slave sending and receiving, and setting a seven-bit address; the i2c-bit file initialization unit sets a seven-bit address; the initialization unit of the signal comprises a signal function setting unit, a semaphore host, a file descriptor fetching unit, an asynchronous reading mark adding unit, an asynchronous reading semaphore setting unit and a keyboard reset unit; the signal setting function unit comprises the steps of acquiring an SIGIO signal, transmitting a main i2c file handle and transmitting an i2c-bit file handle; and the main function writing unit judges the states of fd and fd1 and executes corresponding operation.
A structure sign variable is defined at i2c _ init (), the signal processing function name myread is set:
action.sa_sigaction＝myread；
and (3) transmitting additional information:
action.sa_flags＝SA_SIGINFO；
sigaction () function install signal:
sigaction(SIGIO,&action,NULL)；
the myread code is as follows:
firstly, judging whether the signal type is SIGIO through a sign, then transmitting a file descriptor through a si _ fd member of a siginfo _ t structure, automatically distributing by a system when a device is opened by an open method, and finally entering a processing module, wherein i2c _ readevent (), i2c _ readkb () are respectively processed, and codes are as follows:
thus, the I2C bus driver is signal processed to meet the requirement of real-time interrupt basically.
The above disclosure is only for the preferred embodiments of the invention, but the invention is not limited thereto, and any non-inventive changes that can be made by those skilled in the art and several modifications and amendments made without departing from the principle of the invention shall fall within the protection scope of the invention.
Claims (9)
1. A signal-based linux system I2C driver method, comprising the steps of:
s1: preparing an asynchronous notification mechanism for an enabled file;
s2: designing a driven asynchronous notification interface unit;
s3: designing a signal installation unit;
s4: and designing a functional test unit of the driver.
2. The signal-based linux system I2C driver method of claim 1, wherein: the asynchronous notification mechanism for preparing the enabled file modifies a standard I2C driver under a Linux system, and comprises the steps of adding macro definition USE _ ASYNC in an I2c _ adapter data structure in an I2c.h file, and realizing the definition of variables I2c _ event and queue; adding macro definition USE _ ASYNC in an i2c _ dev _ fos data structure in an i2c _ dev.c file to realize fasync, i2cdev _ fasync and newly adding a static function i2cdev _ fasync;
the i2c _ xxx module sending the SIGIO signal includes that the i2c _ xxx _ add _ bus function under the i2c _ algo _ xxx module increases by i2c _ xxx _ ap ═ adap; in the interrupt function iic _ xxx _ handle of the i2c _ xxx module, the following statement is added before the data processing is finished and ready to return,
#ifdef USE_ASYNC
if(i2c_xxx_ap->i2c_event)
kill_fasync(&(i2c_xxx_ap->i2c_event),SIGIO,POLL_IN)。
3. the signal-based linux system I2C driver method of claim 2, wherein: the design uses a driven asynchronous notification interface unit, an interface method corresponding to the fcntl system call of the user program is set, and when the process uses the fcntl system call to execute the F _ SETOWN command, the process ID number of the owner process is stored in file- > F _ winner; the FASYNC flag is set in the device by the fcntl command F _ SETFL; setting a semaphore host, taking a file descriptor and adding an asynchronous reading mark in a user program; the user program is conditioned for using an asynchronous notification interface.
4. One of the claims 3, characterized in that: the signal installation unit comprises the initialization of semaphore and the installation of a signal function by using sigaction ().
5. The signal-based linux system I2C driver method of claim 4, wherein: the command () function sets three parameters, sets SA _ SIGINFO flag bit in the structure command, specifies the processing function by SA _ command in the command structure, and specifies which signals should be blocked during the execution of the signal processing program by SA _ mask of the structure command.
6. The signal-based linux system I2C driver method of claim 5, wherein: the function test unit of the driver is provided with two I2C devices fd and fd1 to test the application of signals in the driver; the function test unit comprises a main i2c file initialization unit, an i2c-bit file initialization unit, a signal setting function unit and a main function writing unit.
7. The signal-based linux system I2C driver method of claim 6, wherein: the main I2c file initialization unit comprises setting I2C bus controller clock frequency; setting a master sending and receiving and a slave sending and receiving, and setting a seven-bit address; the i2c-bit file initialization unit sets seven-bit address.
8. The signal-based linux system I2C driver method of claim 6, wherein: the initialization unit of the signal comprises the steps of setting a signal function, setting transmission additional information, setting a semaphore and a semaphore host, taking a file descriptor, adding an asynchronous reading mark, setting an asynchronous reading semaphore and resetting a keyboard.
9. The signal-based linux system I2C driver method of claim 6, wherein: the signal setting function unit comprises the steps of acquiring an SIGIO signal, transmitting a main i2c file handle and transmitting an i2c-bit file handle; the main function writing unit judges the states of fd and fd1 for fd and fd1 devices and executes corresponding operations.
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