DM5810/DM6810 Driver for Linux Driver Version 2.0.x User`s Manual
Contents
1. Before calling ioctl file_descriptor must be set up This is not shown here Write to the IRQ Enable Register at base I O address 16 EL ioctl_request access_8 offset 0x10 a DM5810 DM6810 Driver for Linux Disable P14 interrupt bit 0 0 and disable IRQ sharing bit 2 1 LA ioctl request access 8 data 0x04 status ioctl file descriptor DM6810 IOCTL WRITE 8 BITS amp ioctl request GetDriverVersion68 10 bool GetDriverVersion6810 u int32 t version p Description Get the driver version number The version number is an unsigned integer encoding the major minor and patch level numbers NOTE The driver version is encoded according to the formula Version MajorVersion lt lt 16 MinorVersion lt lt 8 PatchLevelNumber Parameters version p Address where version number should be stored If this is NULL then no version number is returned This location is unchanged if the function fails Return Value true Success false version pis NULL Failure Please see the ioctl 2 man page for information on possible values errno may have in this case IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here El status ioctl file descriptor DM6810 IOCTL GET DRIVER VERSION amp ioctl request DM5810 DM6810 Driver f2. 9 DM5810 DM6810 Driver for Linux DIOClearIrq68 10 bool DIOClearIrq68 10 u_int8_t Port Description Clear the Digital IRQ Status bit for the given digital I O port NOTE The digital I O ports exist in pairs Ports 0 amp 1 form a pair as do ports 2 amp 3 and ports 4 amp 5 Therefore clearing the Digital IRQ Status bit for a port also clears the Digital IRQ Status bit for the other port in the pair NOTE There is no need to call this function from an application Interrupts are automatically acknowledged by the driver s interrupt handler Parameters Port Digital I O port to clear IRQ status of Valid values are 0 Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Return Value true Success false Failure with errno set as follows EINVAL Port is not valid Please see the description of the internal function select_dio_control_register for information on other possible values errno may have in this case IOCTL Interface This function makes use of several ioctl requests DIOClearStrobe68 10 bool DIOClearStrobe6810 u_int8_t Port Description Clear the Strobe Status bit in the Read Digital I O Status Register for the given digital I O port NOTE The digital I O ports exist in pairs Ports 0 amp 1 form a pair as do ports 2 amp 3 and ports 4 amp 5 Therefore clearing the Strobe Status bit for a port also
3. ioctl_request access_8 data amp OxF 370OCOC i DM5810 DM6810 Driver for Linux GetLastIntStatus68 10 bool GetLastIntStatus68 1 0 u_int32_t int_count_p u_int8_t status_reg_p bool wait_for_interrupt Description Get the driver s interrupt count and IRQ Status Register value at the time of the most recent interrupt NOTE This function can be used to provide interrupt notification if wait_for_interrupt is set to true In this case the function does not exit the kernel until the driver s interrupt handler wakes the process up NOTE If wait_for_interrupt is true this function will always wait for the next interrupt to occur even if an interrupt just happened NOTE Only bits 0 through 3 in the IRQ Status Register are returned NOTE If you are using this function to wait for interrupts signals can wake up the process before an interrupt occurs If a signal is delivered to the process during a wait no status or count is returned and the application is responsible for dealing with the premature awakening in a reasonable manner Parameters int_count_p Address where interrupt count should be stored Nothing is written here if the function fails status_reg_p Address where Status Register value should be stored Nothing is written here if the function fails wait_for_interrupt Flag indicating whether or not to wait for an interrupt to occur before returning status A value of false means return th
4. 0 If bit 0 is set then interrupt occurred on port 0 1 Fl if ioctl_request access_8 data amp 0x01 fprintf stdout Digital I O port 0 1 generated an interrupt n DIOIsIrq68 10 bool DIOIsIrq68 10 u_int8_t Port Description Determine whether or not the given digital I O port generated an interrupt NOTE The digital I O ports exist in pairs Ports 0 amp 1 form a pair as do ports 2 amp 3 and ports 4 amp 5 Therefore the interrupt state for a port is indistinguishable from the interrupt state for the other port in the pair NOTE This function examines the contents of the port s Read Port Digital I O Status Register NOTE This function is equivalent to DIOIsIRQ68100 NOTE The information returned by this function is unreliable because the driver s interrupt handler clears all interrupt status flags during interrupt acknowledgement Parameters Port Digital I O port to examine interrupt status of Valid values are O Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Return Value false No interrupt occurred true An interrupt occurred DM5810 DM6810 Driver for Linux 24 IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here Re Read the Port 2 3 Digital I O Status R
5. BUIEDING THE DRIVER rede ha duce reeks Sen EA eas Vea aha Sha Sak de EEE 7 BUILDING THE LIBRARY ccccccccscscscscscecscececscecececececececscececscssscscecscasesesecauausuauauauauauauauauauauanananens 8 BUILDING THE EXAMPLE PROGRAMS ccscssscscscssssscscscscscsescsssesssesssesssssssesssesssessseseseseseseseseseees 9 INTERRUPT PERFORMANCE csecsssossossesosssssescosonsstecsonsncoasvossdessceceseesondscosbosseoesbessenbecnesoeseses 10 CONDITIONS AFFECTING PERFORMANCE see 10 IMPROVING PERFORMANCE v 2 ccscesceccacesctedseetcnccecosctecs ov tcnedh tosctech evecaece cobcacceduscaecesdacnsacedectececdacnece 10 REWRITING THE INTERRUPT HANDLER sss ee eee 11 USING THE APE FUNCTIONS cisscssscsssescsiscscsssesssosessssscsaccssccnssvessssonsccaesestsvdetcsccnsecesevsesoesosossoes 13 FUNCTION REFERENCE secssscssssvcsseseccssovicsvessseecessocsssecsestncsaseosvoncescossedoosonsntesserseeessssbeosessosees 14 API FUNCTION GROUPS fii ssssaccascssieciesesssnassctasseeuess coassassssecsoes sees sedessasdenceassvasdandocesussscsssueteesess 15 BICI aN EA V O 5 Fe vice asc eos is di a E A Bi EEE i ER 15 GENER Ale ee eee terete nee Ne seen cate te he rien tee ee ete at EE ae bone Meee ates 15 INTERRUPT CONTROL AND STATUS S agog a e Ed agad aa d a al e aiala 15 TIMER COUNTER CONTROL AND STATUS 15 ALPHABETICAL FUNCTION LISTING sss sss sss ss sss sss sss sss seson sss n enose nnes annan 16 EXAMPLE PROGRAMS REFERENCE ccssccsssssssssssccsccc
6. automatically acknowledged by the driver s interrupt handler Parameters None Return Value None IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here AJ Read the Clear IRQ Register at base I O address 16 AJ ioctl_request access_8 offset 0x10 This value does not matter because it is ignored making the request ps ioctl_request access_8 data 0 status ioctl file_descriptor DM6810 IOCTL READ 8 BITS amp ioctl request ClockDivisor6810 bool ClockDivisor6810 u int8 Timer u_int16_t Divisor Description Set the divisor for the given 8254 timer counter NOTE Before calling this function you must ensure that the indicated timer counter is set to be programmed least significant byte first then most significant byte DM5810 DM6810 Driver for Linux 16 Parameters Timer The timer to operate on Valid values are 0 Timer counter 0 1 Timer counter 1 2 Timer counter 2 Divisor Counter divisor Valid values are 0 through 65535 Return Value true Success false Failure with errno set as follows EINVAL Timer is not valid Please see the description of the internal function outb for information on other possible values errno may have in this case IOCTL Interface This function makes use of several ioctl requests ClockMode68 10 bool
7. 1 my ioctl_request access_8 offset 0x40 Put timer in rate generator mode Sy ioctl_request access_8 offset 0x04 status ioctl file_descriptor DM6810 IOCTL WRITE 8 BITS amp ioctl request CloseBoard6810 bool CloseBoard6810 void Description Close a DM6810 device file DM5810 DM6810 Driver for Linux 18 Parameters None Return Value true Success false Failure Please see the close 2 man page for information on possible values errno may have in this case IOCTL Interface None DIOClearChip6810 bool DIOClearChip6810 u_int8_t Port Description Clear the digital I O chip for the given digital I O port NOTE The digital I O ports exist in pairs Ports 0 amp 1 form a pair as do ports 2 amp 3 and ports 4 amp 5 Therefore clearing the digital I O chip for a port also clears the digital T O chip for the other port in the pair Parameters Port Digital I O port for which to clear chip Valid values are 0 Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Return Value true Success false Failure with errno set as follows EINVAL Port is not valid Please see the descriptions of the internal functions outb and select_dio_control_register for information on other possible values errno may have in this case IOCTL Interface This function makes use of several ioctl requests
8. ClockMode6810 u_int8_t Timer u_int8_t Mode Description Set the mode for the given 8254 timer counter NOTE This function puts the indicated timer counter into binary mode NOTE This function sets the timer counter to read load least significant byte first then most significant byte Parameters Timer The timer to operate on Valid values are 0 Timer counter 0 1 Timer counter 1 2 Timer counter 2 Mode The counter mode to set Valid values are Event count Programmable one shot Rate generator Square wave rate generator Software triggered strobe Hardware triggered strobe Lh LQ HLA a CO DM5810 DM6810 Driver for Linux Return Value true Success false Failure with errno set as follows EINVAL Timer is not valid EINVAL Mode is not valid Please see the description of the internal function outb for information on other possible values errno may have in this case IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here XL Write to the 8254 Timer Counter Control Word Register at base I O address 15 Ae ioctl_request access_8 offset Ox0F Set timer to read load least significant byte first then most significant byte Because bit 0 is set to zero this puts the timer in binary mode Er ioctl request access 8 data 0x30 Operate on timer counter
9. This will be incremented whenever minor yet significant changes are made to the software Changing the minor release number requires updating the software manual C is the patch level number This will be incremented whenever very minor changes are made to the software Changing the patch level number does not require updating the software manual In this document you will see driver version numbers with a letter in them For example 2 0 x indicates that the topic being discussed is applicable to driver versions with a major release number of 2 a minor release number of 0 and any patch level number Occasionally you will notice text placed within the lt and gt characters for example lt installation path gt This indicates that the text represents something which depends upon choices you have made or upon your specific system configuration DM5810 DM6810 Driver for Linux 6 Installation Instructions Extracting the Software All software comes packaged in a gzip d tar file named dm6810 Linux v2 0 x tar gz First decide where you would like to place the software Next change your current directory to the directory in which you have chosen to install the software by issuing the command cd lt installation path gt Then extract the software by issuing the tar xvzf lt path to tar file gt dm68 10_Linux_v2 0 x tar gz command this will create a directory dm6810_Linux_v2 0 x that contains all files comprising the sof
10. compile Some of the areas requiring attention on your part are All header files have been renamed Users upgrading from a previous driver version will need to modify source code to include the appropriate header files All header files have been relocated to include Be sure to update any files which contain hardcoded header file paths 6810 has been appended to all library function names with the exception of class constructors and destructors Library functions which accepted a digital I O chip number now accept a digital I O port number Interrupt notification via signals is no longer supported The new notification paradigm provides a function which can block in the kernel until an interrupt occurs The driver now acknowledges all interrupts in the interrupt handler Therefore interrupt status is no longer available to an application through certain functions All classes have been coalesced into a single class DM6810Device The DM6810 dev entry file names have changed For example the device file previously named dev rtd dm68 10hr device0 is now called dev rtd dm68 10 0 The following function reference provides for each library routine a prototype description explanation of parameters and return value or error code By looking at a function s entry you should gain an idea of 1 why it would be used 2 what it does 3 what information is passed into it 4 what information it passes back 5 how to interpret error co
11. false Failure Please see the description of the internal function outb for information on possible values errno may have in this case IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here ay DM5810 DM6810 Driver for Linux 34 Write to the IRQ Enable Register at base I O address 16 L G ioctl_request access_8 offset 0x10 Enable P14 interrupt Because bit 1 is set to zero interrupts occur on positive edge of pulse ry ioctl request access 8 data 0x01 Disable IRQ sharing Af ioctl_request access_8 data 0x04 status ioctl file_descriptor DM6810 IOCTL WRITE 8 BITS amp ioctl request EnableP 14IRQ6810 bool EnableP14IRQ6810 bool Enable Description Enable or disable P14 interrupts on a DM68 10 device NOTE This function also modifies the library s internal cache of the board s Clear IRQ IRQ Enable Register value Parameters Enable Flag indicating whether or not P14 interrupts should be enabled A value of true means enable P14 interrupts A value of false means disable P14 interrupts Return Value true Success false Failure Please see the description of the internal function outb for information on possible values errno may have in this case IOCTL Interface dm6810_ioctl_argument_t ioctl_request int file_descriptor int status
12. follows EINVAL Port is not valid Please see the description of the internal functions outb and select_dio_control_register for information on other possible values errno may have in this case IOCTL Interface This function makes use of several ioctl requests DM5810 DM6810 Driver for Linux 30 DIOStrobeEnable6810 bool DIOStrobeEnable6810 u int8 t Port bool Enable Description Enable or disable data strobing for the given digital I O port NOTE The digital I O ports exist in pairs Ports 0 amp 1 form a pair as do ports 2 amp 3 and ports 4 amp 5 Therefore changing the data strobe state for a port also changes the data strobe state for the other port in the pair NOTE Only the even numbered ports support data strobing Parameters Port Port to set data strobing for Valid values are O Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Enable Flag indicating whether or not data strobe should be enabled A value of true means enable data strobe A value of false means disable data strobe Return Value true Success false Failure with errno set as follows EINVAL Port is not valid Please see the description of the internal function outb for information on other possible values errno may have in this case IOCTL Interface This function makes use of several ioctl requests DIOWrite63 10 bool DIO
13. DM5810 DM6810 Driver for Linux Driver Version 2 0 x User s Manual TIGO RTD Embedded Technologies Inc Real Time Devices Accessing the Analog World SWM 640010019 rev A RTD Embedded Technologies INC 103 Innovation Boulevard State College PA 16803 0906 Phone 1 814 234 8087 FAX 1 814 234 5218 E mail sales rtd com techsupport rtd com web site http www rtd com DM5810 DM6810 Driver for Linux Revision History 01 17 2005 Revision A issued Documented for ISO9000 DM5810 DM6810 Driver for Linux Published by RTD Embedded Technologies Inc 103 Innovation Boulevard State College PA 16803 0906 Copyright 2005 by RTD Embedded Technologies Inc All rights reserved Printed in U S A The RTD Logo and dataModule are registered trademarks of RTD Embedded Technologies All other trademarks appearing in this document are the property of their respective owners m DMS5810 DM6810 Driver for Linux Table of Contents TABEE OF CONTENTS TT 4 INTRODUCTION 4533 EEN e E a erase i a o snart 5 NOTATIONAL CONVENTIONS cccscsscssssssssccccccccsssscesscccccsssssssceccccessssscsscececescssssscsesecesceseces 6 INSTALLATION INSTRUCT IONG cccccscsssscsscsccssssssssscccccsscssccseccccssssssssseccccescsssssscesecesceseces 7 EXTRACTING THE SOFTWARE cccccccscscscscecsceceessscscececsescscscscscscscscscscacscscacacscacacasasasaueueuauauenenenens 7 CONTENTS OF INSTALLATION DIRECTORY 7
14. E PURCHASER S SOLE REMEDY SHALL BE REPAIR OR REPLACEMENT AS PROVIDED ABOVE UNDER NO CIRCUMSTANCES WILL RTD Embedded Technologies BE LIABLE TO THE PURCHASER OR ANY USER FOR ANY DAMAGES INCLUDING ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES EXPENSES LOST PROFITS LOST SAVINGS OR OTHER DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PRODUCT SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF INCIDENTAL OR CONSEQUENTIAL DAMAGES FOR CONSUMER PRODUCTS AND SOME STATES DO NOT ALLOW LIMITATIONS ON HOW LONG AN IMPLIED WARRANTY LASTS SO THE ABOVE LIMITATIONS OR EXCLUSIONS MAY NOT APPLY TO YOU THIS WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS AND YOU MAY ALSO HAVE OTHER RIGHTS WHICH VARY FROM STATE TO STATE DM5810 DM68 10 Driver for Linux RTD Embedded Technologies Inc 103 Innovation Boulevard State College PA 16803 0906 USA Our website www rtd com DM5810 DM6810 Driver for Linux 48
15. TE 8 BITS amp ioctl request SetUserClock6810 float SetUserClock68 10 u_int8_t Timer float InputRate float OutputRate Description Set the given timer counter into rate generator mode and program its divisor value based upon the specified input and output rates Parameters Timer The timer to program Valid values are 0 Timer counter 0 1 Timer counter 1 2 Timer counter 2 InputRate Input clock rate to timer counter OutputRate Desired output rate Return Value Actual clock frequency programmed IOCTL Interface This function makes use of several ioctl requests DM5810 DM6810 Driver for Linux 44 WriteByte68 10 bool WriteByte6810 u_int8_t offset u_int8_t data Description Write an 8 bit value to the given offset within a DM6810 board s I O memory NOTE It is strongly suggested that you use other library functions instead of directly accessing a board s registers Parameters offset Offset within I O memory to write data Data to write Return Value true Success false Failure with errno set as follows EINVAL offset is not valid EOPNOTSUPP offset is valid but it represents a read only register Please see the ioctl 2 man page for information on other possible values errno may have in this case IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_descriptor must be set up This is not shown her
16. Write6810 u_int8_t Port u_int8_t Data Description Write an 8 bit value to the given digital I O port a DM5810 DM6810 Driver for Linux Parameters Port The port to write to Value values are 0 Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Data Data to write Valid values are 0 through 255 Return Value true Success false Failure with errno set as follows EINVAL Port is not valid Please see the description of the internal function outb for information on other possible values errno may have in this case IOCTL Interface dm6810_ioctl_argument_t ioctl_request int file_descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here Af Write to the Digital I O Port 3 Register at base I O address 5 ioctl_request access_8 offset 0x05 Write a value with bits 4 through 7 set to one sy ioctl request access 8 data 0xF0 status ioctl file descriptor DM6810 IOCTL WRITE 8 BITS amp ioctl request DM6810Device DM6810Device void Description DM6810Device class constructor DM5810 DM6810 Driver for Linux 32 Parameters None Return Value None Constructors do not return a value IOCTL Interface None DM6810Device DM6810Device void Description DM6810Device class destructor Parameters None Retu
17. ation environment must be running the exact same version of the kernel as your production machine s otherwise the kernel module may not load or may load improperly After the code is built you can then move the resulting object files libraries and executables to the production system s Building the driver consists of several steps 1 compiling the source code 2 loading the resulting kernel module into the kernel and 3 creating hardware device files in the dev directory To perform any of the above steps you must change your current directory to driver The file Makefile contains rules to assist you 7 DM5810 DM6810 Driver for Linux To compile the source code issue the command make The GNU C compiler gcc is used to build the driver code This will create the driver object file which is named rtd dm6810 0 on 2 4 kernels and rtd dm6810 ko on 2 6 kernels Before the driver can be used it must be loaded into the currently running kernel Using the command make insmod will load the DM68 10 driver into the kernel This target assumes that A single DM68 10 is installed The board s base I O address is set to the factory default of 0x300 The DM6810 is jumpered to use IRQ 5 If the previous assumptions do not match your hardware setup you will need to edit the Makefile and change this rule to reflect your board configuration or manually issue an appropriate insmod command For the 2 4 kernel when you load the kerne
18. ccsscsscscscccccsssssseeccccesssssssececcssees 46 LIMITED WARRANTY oicisccsstesicsscdsacensceescbedeescesanceasev cdeocebansgevesscbecbessebanssssendcdeacoodvaseasbscteacesase 47 DM5810 DM6810 Driver for Linux iv Introduction This document targets anyone wishing to write Linux applications for an RTD DM5810 or DM6810 dataModule It provides information on building the software and about the Application Programming Interface used to communicate with the hardware and driver Each high level library function is described as well as any low level ioctl system call interface it may make use of The diagram below 1 provides a general overview of what hardware and software entities are involved in device access 2 shows which units communicate with each other and 3 illustrates the methods used to transfer data and control information Application Application Application C Function Calls C Function Calls C Function Calls Library ioctl System Calls User Space Kernel Space Driver Software Memory Accesses Hardware Electrical Signals Hardware 5 DM5810 DM6810 Driver for Linux Notational Conventions RTD Linux drivers are assigned version numbers These version numbers take the form A B C where A is the major release number This will be incremented whenever major changes are made to the software Changing the major release number requires updating the software manual B is the minor release number
19. clears the Strobe Status bit for the other port in the pair DM5810 DM6810 Driver for Linux 20 NOTE DIOClearChip6810 does not clear the Strobe Status bit During program initialization DIOClearStrobe6810 must be called to ensure that the bit is cleared Once data is being strobed into an even numbered port reading data from that port will clear the Strobe Status flag NOTE Even though this function accepts an odd numbered port it is internally translated into the even numbered port in the pair since only the even numbered ports support data strobing Parameters Port Digital I O port to clear strobe status of Valid values are 0 Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Return Value true Success false Failure with errno set as follows EINVAL Port is not valid IOCTL Interface dm6810_ioctl_argument_t ioctl_request int file_descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here AY Read the Digital I O Port 0 Register at base I O address 0 S ioctl_request access_8 offset 0x00 This value does not matter because it is ignored making the request E ioctl request access 8 data 0 status ioctl file descriptor DM6810 IOCTL READ 8 BITS amp ioctl request a DM5810 DM6810 Driver for Linux DIOEnableIrq68 10 bool DIOEnableIrq68 10 u_int8_
20. e 41 DM5810 DM6810 Driver for Linux IOCTL Interface None ReadByte68 10 bool ReadByte68 10 u_int8_t offset u_int8_t data_p Description Read an 8 bit value from the given offset within a DM6810 board s I O memory NOTE It is strongly suggested that you use other library functions instead of directly accessing a board s registers Parameters offset Offset within I O memory to read data_p Address where data read should be stored Nothing is written here if the function fails Return Value true Success false Failure with errno set as follows EINVAL offset is not valid EOPNOTSUPP offset is valid but it represents a write only register Please see the ioctl 2 man page for information on other possible values errno may have in this case IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here By Read the IRQ Status Register at base I O address 17 ep ioctl request access 8 offset 0x11 This value does not matter because it is ignored making the request However after ioctl returns the structure member will contain the register contents EJ DM5810 DM6810 Driver for Linux 42 ioctl request access 8 data 0 status ioctl file descriptor DM6810 IOCTL READ 8 BITS amp ioctl request ReadTimerCounter68 10 u_intl6_t ReadTimerCoun
21. e XI Write to the Digital I O Port 1 Register at base I O address 1 Af ioctl_request access_8 offset 0x01 Write all zeros to the port 3 ioctl request access 8 data 0x00 status ioctl file descriptor DM6810 IOCTL WRITE 8 BITS amp ioctl request 45 DM5810 DM68 10 Driver for Linux Example Programs Reference Name basic test digital interrupts digital io dio test external int interrupt test interrupt wait strobe timer interrupts timers timer test Remarks Tests the basic functionality of the driver and library Demonstrates how to use digital interrupts Demonstrates reading from and writing to the digital I O ports Tests the library functions related to digital I O Demonstrates how to set up external interrupts Tests the library interrupt related functions Demonstrates waiting for interrupt notification Demonstrates how to set up data strobing Demonstrates generating P14 interrupts via timer counter 2 Demonstrates using the 8254 timer counters in rate generator and event count modes Tests the basic functionality of the 8254 timer counter library functions DM5810 DM6810 Driver for Linux 46 Limited Warranty 47 RTD Embedded Technologies Inc warrants the hardware and software products it manufactures and produces to be free from defects in materials and workmanship for one year following the date of shipment from RTD Embedded Technologies INC This warranty is limit
22. e most recent interrupt status without waiting A value of true means wait for an interrupt to occur and then return status Return Value true Success false Failure with errno set as follows EINTR The process received a signal before an interrupt occurred Please see the ioctl 2 man page for information on other possible values errno may have in this case DM5810 DM6810 Driver for Linux 38 IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here Ref Wait in the kernel until the next interrupt occurs before returning status xy ioctl_request last_int_status wait_for_interrupt OxFF These values do not matter because they are ignored making the request However after ioctl returns the structure members will contain the requested information XI ioctl request last int status status reg 0 ioctl request last int status int count 0 status ioctl file_descriptor DM6810_IOCTL_GET_LAST_INT_STATUS amp ioctl request if status 0 fprintf stdout Status at last interrupt n fprintf stdout IRQ Status O0x x n ioctl_request last_int_status status_reg i fprintf stdout interrupts Sd n ioctl_request last_int_status int_count i InitBoard6810 void InitBoard68 1 0 void Description Initialize DM6810 device clas
23. e kernel version as the production machine that will host your application almost certainly invites trouble If you ever need to unload the driver from the kernel you can use the command make rmmod Building the Library The example programs and your application use the DM6810 library so it must be built before any of these can be compiled To build the library change your current directory to lib and issue the command make The GNU C compiler g is used to compile the library source code To prevent compatibility problems any source code which makes use of library functions should also be built with g The DM68 10 library is statically linked and is created in the file librtd dm68 10 a DM5810 DM6810 Driver for Linux 8 Building the Example Programs The example programs may be compiled by changing your current directory to examples and issuing the command make which builds all the example programs If you wish to compile a subset of example programs there are targets in Makefile to do so For example the command make digital interrupts digital io interrupt wait will compile and link the source files digital interrupts cpp digital io cpp and interrupt wait cpp The GNU C compiler g is used to compile the example program code 9 DM5810 DM6810 Driver for Linux Interrupt Performance Conditions Affecting Performance The driver provides an interrupt notification feature which applications can use to wa
24. ed to the original purchaser of product and is not transferable During the one year warranty period RTD Embedded Technologies will repair or replace at its option any defective products or parts at no additional charge provided that the product is returned shipping prepaid to RTD Embedded Technologies All replaced parts and products become the property of RTD Embedded Technologies Before returning any product for repair customers are required to contact the factory for an RMA number THIS LIMITED WARRANTY DOES NOT EXTEND TO ANY PRODUCTS WHICH HAVE BEEN DAMAGED AS A RESULT OF ACCIDENT MISUSE ABUSE such as use of incorrect input voltages improper or insufficient ventilation failure to follow the operating instructions that are provided by RTD Embedded Technologies acts of God or other contingencies beyond the control of RTD Embedded Technologies OR AS A RESULT OF SERVICE OR MODIFICATION BY ANYONE OTHER THAN RTD Embedded Technologies EXCEPT AS EXPRESSLY SET FORTH ABOVE NO OTHER WARRANTIES ARE EXPRESSED OR IMPLIED INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY AND FIT NESS FOR A PARTICULAR PURPOSE AND RTD Embedded Technologies EXPRESSLY DISCLAIMS ALL WARRANTIES NOT STATED HEREIN ALL IMPLIED WARRANTIES INCLUDING IMPLIED WARRANTIES FOR MECHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE LIMITED TO THE DURATION OF THIS WARRANTY IN THE EVENT THE PRODUCT IS NOT FREE FROM DEFECTS AS WARRANTED ABOVE TH
25. egister at base I O address 7 K ioctl_request access_8 offset 0x07 This value does not matter because it is ignored making the request However after ioctl returns the structure member will contain the register contents aif ioctl_request access_8 data 0 status ioctl file_descriptor DM6810 IOCTL READ 8 BITS amp ioctl request if status 0 If bit 7 is set then interrupt occurred on port 2 3 K if ioctl_request access_8 data amp 0x80 fprintf stdout Digital I O port 2 3 generated an interrupt n DIOIsStrobe6810 bool DIOIsStrobe6810 u_int8_t Port Description Determine whether or not data has been strobed into the given digital I O port NOTE The digital I O ports exist in pairs Ports 0 amp 1 form a pair as do ports 2 amp 3 and ports 4 amp 5 Therefore the strobe state for a port is indistinguishable from the strobe state for the other port in the pair NOTE Only the even numbered ports support data strobing Parameters Port Digital I O port to examine strobe status of Valid values are O0 Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 3 0 0 0 0 DM5810 DM6810 Driver for Linux Return Value false Data not strobed true Data strobed IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_de
26. egister6810 u_int8_t Port u_int8_t Select Description Select which control register is accessed for the given digital I O port NOTE This function is not normally required in an application The other library functions which require digital I O control register access select that register internally Parameters Port The port to select control register for Value values are 0 Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Select Control register to access Valid values are 0 Clear Register 1 Even numbered Port Direction Register 2 Odd numbered Port Direction Register 3 IRQ Source Register Return Value true Success false Failure with errno set as follows EINVAL Port is not valid EINVAL Select is not valid DM5810 DM6810 Driver for Linux 28 Please see the description of the internal function select dio control register for information on other possible values errno may have in this case IOCTL Interface This function makes use of several ioctl requests DIOSetIRQSource6810 bool DIOSetIRQSource68 10 u_int8_t Port u_int8_t Bit Description Set which bit generates a digital interrupt for the given digital I O port NOTE The digital I O ports exist in pairs Ports 0 amp 1 form a pair as do ports 2 amp 3 and ports 4 amp 5 Therefore changing the digital interrupt source for a port will overwrite any di
27. gital I O ports exist in pairs Ports 0 amp 1 form a pair as do ports 2 amp 3 and ports 4 amp 5 Therefore the interrupt state for a port is indistinguishable from the interrupt state for the other port in the pair NOTE This function examines the contents of the IRQ Status Register at base I O address 17 NOTE This function is equivalent to DIOIsIrq6810 NOTE The information returned by this function is unreliable because the driver s interrupt handler clears all interrupt status flags during interrupt acknowledgement Parameters Port Digital I O port to examine interrupt status of Valid values are 0 Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Return Value false No interrupt occurred true An interrupt occurred IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here El Read the IRQ Status Register at base I O address 17 X ioctl_request access_8 offset 0x11 3 DM5810 DM6810 Driver for Linux This value does not matter because it is ignored making the request However after ioctl returns the structure member will contain the register contents ioctl_request access_8 data 0 status ioctl file_descriptor DM6810_IOCTL_READ_8 BITS amp ioctl request if status
28. gital interrupt source set for the other port in the pair Parameters Port Port to set digital interrupt source for Valid values are 0 Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Bit The bit which generates a digital interrupt Valid values are U BitO 1 Bitl 2 Bit2 3 Bit3 4 Bit4 5 Bit5 6 Bit6 7 Bit7 Return Value true Success false Failure with errno set as follows EINVAL Port is not valid EINVAL Bit is not valid 2 BM5810 DM6810 Driver for Linux Please see the description of the internal functions outb and select dio control register for information on other possible values errno may have in this case IOCTL Interface This function makes use of several ioctl requests DIOSetPortDirection6810 bool DIOSetPortDirection68 10 u_int8_t Port u_int8_t Direction Description Set the direction input or output for the bits in the given digital I O port Parameters Port Port to set bit direction for Valid values are 0 Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Direction Bit mask which controls bit direction A zero in a bit position means the corresponding port bit is set to input A one in a bit position means the corresponding port bit is set to output Return Value true Success false Failure with errno set as
29. it for an interrupt to occur Once this interrupt happens an application usually performs some sequence of actions and then waits for another interrupt This paradigm by its nature involves both kernel and user level the driver resides in kernel space and your application resides in user space This model provides flexibility and reduces complexity but has limitations like all software There are many things which can affect performance when the user application waits for an interrupt and then is notified of its occurrence by the driver Putting a user process to sleep in the kernel to wait for the interrupt and then waking it up is expensive in terms of time needed This delay interferes with the usable work a process can do and how fast it can do it Additionally when a process exits the kernel there may be other work for it to do for example checking for and handling signals before it resumes what it was doing in user space Dependent upon the other processes runnable on a system your application may not be selected to run on the CPU for some time after it is woken up by an interrupt Ignoring other factors for the moment the higher the number of runnable processes the more likely it is that your application will not be selected to run right away If the user application incurs a page fault that is accesses an address which is valid but not currently loaded into main memory the process must be put to sleep until the kernel brings that memor
30. l driver the message Warning loading rtd dm68 10 0 will taint the kernel non GPL license Proprietary will be printed on your screen You can safely ignore this message since it pertains to GNU General Public License GPL licensing issues rather than to driver operation For the 2 6 kernel when you load the kernel driver no warnings will appear on your screen However the warning module license Proprietary taints kernel will be written to the system log when the module is loaded You can safely ignore this message since it pertains to GNU General Public License GPL licensing issues rather than to driver operation The final step is to create dev entries for the hardware Versions of the driver prior to 2 0 0 always assumed a character device major number of 252 when registering the boards and creating the dev entries Instead the driver now asks the kernel to dynamically assign a major number Since this major number may change each time you load the driver the best way to create the device files is to use the command make devices this generates four files in dev named rtd dm68 10 0 through rtd dm68 10 3 Be aware that driver Makefile uses the uname r command to determine which kernel version it is running on It does this to set up separate make rules and variables for the 2 4 and 2 6 kernels which allows one set of targets to work on both kernels Compiling the driver on a development machine which does not run the sam
31. nditions that may arise and 6 the ioctlQ system call interface if the function makes use of a single ioctl call Note that errno codes other than the ones indicated in the following pages may be set by the library functions Please see the ioctl 2 man page for more information 3 0 0 0 0 0 BM5810 DM6810 Driver for Linux Function Reference DM5810 DM6810 Driver for Linux API Function Groups Digital I O DIOClearChip6810 DIOClearIrq6810 DIOClearStrobe6810 DIOEnableIrq68 10 DIOIsIrq68 10 DIOIsIRQ6810 DIOIsStrobe68 10 DIORead6810 DIOSelectClock68 10 DIOSelectRegister68 10 DIOSetIRQSource6810 DJOSetPortDirection6810 DIOStrobeEnable68 10 DIOWrite6810 General CloseBoard68 10 DM68 10Device DM6810Device GetDriverVersion68 10 InitBoard6810 OpenBoard68 10 ReadByte68 10 WriteB yte63 10 Interrupt Control and Status ClearP 14IRQ6810 EnableIRQSharing68 10 EnableP14IRQ6810 GetIRQStatus6810 GetLastIntStatus68 10 IsP14IRQ6810 LoadIRQRegister68 10 SetP14IRQPolarity6810 Timer Counter Control and Status ClockDivisor6810 ClockMode6810 DoneTimer68 10 ReadTimerCounter68 10 SetUserClock6810 15 DM5810 DM6810 Driver for Linux Alphabetical Function Listing ClearP14IRQ6810 void ClearP14IRQ6810 void Description Clear a DM6810 device s P14 interrupt status flag This will acknowledge a P14 interrupt which has occurred NOTE There is no need to call this function from an application Interrupts are
32. nges you can make are to modify the system configuration such that the process is not started at boot ensure that the capability s kernel module is not loaded or disable the functionality at the hardware level The smaller the number of processes the more likely it is that your application will be granted the CPU when it needs it DM5810 DM6810 Driver for Linux 10 A process can lock its memory pages into main memory to prevent page faults Not having to wait for a page fault to be serviced means that a process has more time available for useful work Locking pages into memory during program initialization ensures that all pages are resident in memory thus any access to them will not fault There are some situations in which page faults can still occur but locking pages into memory greatly reduces the likelihood of them occurring Please see the mlockall 2 man page for more information You can change a process scheduling priority and class under Linux A process scheduling priority can be increased so that it will be chosen to run before other processes with lower priority Changing a process scheduling class can disable scheduling time quantums for it which means that the process will not be rescheduled just because its CPU time slice has expired You must exercise extreme caution when modifying scheduling parameters because a process can enter a state where it will be given preference over all other processes thus deferring certain sy
33. or Linux 36 if status 0 u_int32_t version version ioctl_request version driver_version fprintf stdout Major version Sd n version gt gt 16 amp OXF fprintf stdout Minor version Sd n version gt gt 8 amp OxF fprintf stdout Patch level d n version amp OxF GetIRQStatus6810 u_int8_t GetIRQStatus68 10 void Description Get the contents of a board s IRQ Status Register at base I O address 17 NOTE Only bits 0 through 3 are returned NOTE The information returned by this function is unreliable because the driver s interrupt handler clears all interrupt status flags during interrupt acknowledgement Parameters None Return Value IRQ Status Register contents Please see the hardware manual for the interpretation of register bits IOCTL Interface dm6810_ioctl_argument_t ioctl_request int file_descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here 3y Read the IRQ Status Register at base I O address 17 S ioctl_request access_8 offset 0x11 This value does not matter because it is ignored making the request However after ioctl returns the structure member will contain the register contents XIL ioctl request access 8 data 0 status ioctl file descriptor DM6810 IOCTL READ 8 BITS amp ioctl request if status 0 fprintf stdout IRQ Status 0x xYn
34. r after ioctl returns the structure member will contain the register contents ioctl_request access_8 data 0 status ioctl file_descriptor DM6810 IOCTL READ 8 BITS amp ioctl request if status 0 fprintf stdout Port 1 input 0x x n ioctl_request access_8 data DIOSelectClock6810 bool DIOSelectClock6810 u_int8_t Port bool Programmable Description Select sampling clock for the given digital I O port NOTE The digital I O ports exist in pairs Ports 0 amp 1 form a pair as do ports 2 amp 3 and ports 4 amp 5 Therefore setting the sampling clock for a port also sets the same sampling clock for the other port in the pair Parameters Port Port to set clock for Valid values are O Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Programmable Flag to indicate whether or not 8254 Timer Counter should be used A value of false means use the 8 MHz system clock A value of true mean use the 8254 Timer Counter 1 7 0 0 0 0 DM5810 DM6810 Driver for Linux Return Value true Success false Failure with errno set as follows EINVAL Port is not valid Please see the description of the internal function outb for information on other possible values errno may have in this case IOCTL Interface This function makes use of several ioctl requests DIOSelectRegister68 10 bool DIOSelectR
35. r68 10 u_int8_t Value Description Load an 8 bit value into a board s Clear IRQ IRQ Enable Register at base I O address 16 DM5810 DM6810 Driver for Linux 40 NOTE This function also sets the library s internal cache of the board s Clear IRQ IRQ Enable Register value Parameters Value Value to store in register Valid values are 0 through 7 Please see the hardware manual for the interpretation of the register s bits Return Value true Success false Failure Please see the description of the internal function outb for information on possible values errno may have in this case IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here Write to the IRQ Enable Register at base I O address 16 L G ioctl_request access_8 offset 0x10 Enable P14 interrupt bit 0 1 set IRQ polarity to negative edge bit 1 1 and disable IRQ sharing bit 2 1 v ioctl request access 8 data 0x07 status ioctl file descriptor DM6810 IOCTL WRITE 8 BITS amp ioctl request OpenBoard68 10 bool OpenBoard68 1 0 u_int32_t nDevice Description Open a DM6810 device file Parameters nDevice Minor number of DM6810 device file Return Value true Success false Failure Please see the open 2 man page for information on possible values errno may have in this cas
36. rn Value None Destructors do not return a value IOCTL Interface None DoneTimer68 10 bool DoneTimer68 1 0 void Description Set each timer counter into rate generator mode and load each with a divisor value of two Parameters None 33 DM5810 DM6810 Driver for Linux Return Value true Success false Failure Please see the descriptions of ClockMode6810 and ClockDivisor6810 for information on possible values errno may have in this case IOCTL Interface This function makes use of several ioctl requests EnableIRQSharing68 10 bool EnableIRQSharing68 1 0 u_int8_t Enable Description Enable or disable a board s interrupt sharing feature NOTE This function also modifies the library s internal cache of the board s Clear IRQ IRQ Enable Register value NOTE The DM68 10 interrupt handler is not designed to process interrupts shared between devices To avoid unpredictable behavior or worse do not share an interrupt between devices NOTE Interrupts do not need to be shared in order to use several interrupt sources on a single board For example if you wish to use both P14 and port 0 digital interrupts on a single DM6810 device then interrupts do not need to be shared Parameters Enable Flag indicating whether or not interrupt sharing should be enabled A value of 0 means disable interrupt sharing Any other value means enable interrupt sharing Return Value true Success
37. s library state This consists of clearing the library s internal cache of the board s Clear IRQ IRQ Enable Register value NOTE This function does not update the board s Clear IRQ IRQ Enable Register Parameters None Return Value None IOCTL Interface None m DM5810 DM6810 Driver for Linux IsP14IRQ6810 bool IsP14TRQ68 10 void Description Determine whether or not a board s interrupt circuit generated a P14 interrupt NOTE The information returned by this function is unreliable because the driver s interrupt handler clears all interrupt status flags during interrupt acknowledgement Parameters None Return Value false No interrupt occurred true An interrupt occurred IOCTL Interface dm6810 ioctl argument t ioctl request int file descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here R7 Read the IRQ Status Register at base I O address 17 ah ioctl_request access_8 offset 0x11 This value does not matter because it is ignored making the request However after ioctl returns the structure member will contain the register contents Kop ioctl request access 8 data 0 status ioctl file descriptor DM6810 IOCTL READ 8 BITS amp ioctl request if status 0 if ioctl_request access_8 data amp 0x08 fprintf stdout P14 interrupt occurred n LoadIRQRegister68 10 bool LoadIRQRegiste
38. scriptor must be set up This is not shown here Ap Read the Port 4 5 Digital I O Status Register at base I O address 11 EJ ioctl_request access_8 offset 0x0B This value does not matter because it is ignored making the request However after ioctl returns the structure member will contain the register contents XL ioctl request access 8 data 0 status ioctl file descriptor DM6810 IOCTL READ 8 BITS amp ioctl request if status 0 If bit 6 is set then data strobe occurred on port 4 Ej if ioctl request access 8 data amp 0x40 fprintf stdout Data strobed into digital I O port 4 n DIORead68 10 u_int8_t DIORead6810 u_int8_t Port Description Read an 8 bit value from the given digital I O port Parameters Port The port to read from Value values are 0 Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 DM5810 DM6810 Driver for Linux 26 Return Value 8 bit value from specified digital I O port IOCTL Interface dm6810_ioctl_argument_t ioctl_request int file_descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here k Read the Digital I O Port 1 Register at base I O address 1 KOL ioctl_request access_8 offset 0x01 This value does not matter because it is ignored making the request Howeve
39. stem activity The system may even become unresponsive in some ways Please see the sched_setscheduler 2 man page for more information If it s possible to assign a specific interrupt pick one that has a higher priority than other interrupts This will allow your device s interrupt to take precedence over other lower priority interrupts that you may not be as interested in Again extreme caution must be used because deferring certain interrupts may affect system activity As a last resort you can rewrite the driver s interrupt handler to implement whatever functionality you require The upside is that doing so offers the most control over interrupt response The downside is that this approach requires kernel programming knowledge Rewriting the Interrupt Handler Suppose that you have the following requirements 1 the only interrupt being used is the digital interrupt on port 0 1 2 whenever a digital interrupt occurs the value on digital I O port 2 should be read and 3 on digital interrupt occurrence the value 0x01 should be written to digital I O port 5 Furthermore assume the interrupts occur fast enough that dealing with them in user space is unreliable Because the interrupt handler provided with the driver offers generic services suitable for a wide range of purposes it does not provide the functionality indicated above Therefore to meet your requirements you must rewrite the interrupt handler A detailed description of wri
40. t Port bool Enable Description Enable or disable digital interrupts for the given digital I O port NOTE The digital I O ports exist in pairs Ports 0 amp 1 form a pair as do ports 2 amp 3 and ports 4 amp 5 Therefore changing the digital interrupt state for a port also changes the digital interrupt state for the other port in the pair NOTE If you are using digital interrupts make sure data strobing is disabled for the port s which will generate the interrupts Having data strobe enabled for a port disables digital interrupts for that port Parameters Port Digital I O port to modify interrupt state for Valid values are O Digital I O port 0 1 Digital I O port 1 2 Digital I O port 2 3 Digital I O port 3 4 Digital I O port 4 5 Digital I O port 5 Enable Flag indicating whether or not digital interrupts should be enabled A value of true means enable digital interrupts A value of false means disable digital interrupts Return Value true Success false Failure with errno set as follows EINVAL Port is not valid Please see the description of the internal function outb for information on other possible values errno may have in this case IOCTL Interface This function makes use of several ioctl requests DM5810 DM6810 Driver for Linux 22 DIOISIRQ6810 bool DIOIsIRQ6810 u_int8_t Port Description Determine whether or not the given digital I O port generated an interrupt NOTE The di
41. ter68 10 u_int8_t Timer Description Read the count for the given timer counter Parameters Timer The timer to operate on Valid values are 0 Timer counter 0 1 Timer counter 1 2 Timer counter 2 Return Value 16 bit counter value IOCTL Interface This function makes use of several ioctl requests SetP14IRQPolarity6810 bool SetP14IRQPolarity6810 u_int8_t Polarity Description Control whether P14 interrupts occur on rising or falling edge of pulse NOTE This function also modifies the library s internal cache of the board s Clear IRQ IRQ Enable Register value Parameters Polarity Selects pulse edge which triggers an interrupt A value of 0 means rising edge Any other value means falling edge Return Value true Success false Failure Please see the description of the internal function outb for information on possible values errno may have in this case 43 DM5810 DM6810 Driver for Linux IOCTL Interface dm6810_ioctl_argument_t ioctl_request int file_descriptor int status Before calling ioctl file_descriptor must be set up This is not shown here By Write to the IRQ Enable Register at base I O address 16 rad ioctl_request access_8 offset 0x10 Enable P14 interrupt bit 0 1 set IRQ polarity to positive edge bit 1 0 and disable IRQ sharing bit 2 1 KL ioctl request access 8 data 0x05 status ioctl file descriptor DM6810 IOCTL WRI
42. ting interrupt handlers lies beyond the scope of this document What follows is pseudo code for an interrupt handler which implements the desired behavior interrupt_handler Determine interrupt status EL read IRQ Status Register at offset 0x11 if bit 0 is not set in register then Spurious interrupt Er exit end if nm 000 0 DM5810 DM6810 Driver for Linux Acknowledge the interrupt This consists of two steps 1 writing the appropriate value to the Port 0 1 Program Digital Mode Register to select clear mode access to Port 0 1 Clear IRQ Register and 2 reading Port 0 1 Clear IRQ Register to acknowledge and clear the interrupt Rf write to Port 0 1 Program Digital Mode Register at offset 0x03 read Port 0 1 Clear IRQ Register at offset 0x02 Read value on digital I O port 2 ke read Digital I O Port 2 Register at offset 0x04 Write 0x01 to digital I O port 5 EJ write 0x01 to Digital I O port 5 Register at offset 0x09 DM5810 DM6810 Driver for Linux 12 Using the API Functions DM6810 hardware and the associated driver functionality can be accessed through the library API Application Programming Interface functions Applications wishing to use library functions must include the include dm6810_library h header file and be statically linked with the lib librtd dm68 10 a library file Because of changes made in driver version 2 0 0 existing source code which uses the library will not
43. tware package Contents of Installation Directory Once the tar file is extracted you should see the following files and directories within dm6810_Linux_v2 0 x driver examples include lib CHANGES TXT LICENSE TXT README TXT The file CHANGES TXT describes the changes made to the software for this release as well as for previous releases The file LICENSE TXT provides details about the RTD end user license agreement which must be agreed to and accepted before using this software The file README TXT contains a general overview of the software and contact information should you experience problems have questions or need information The directory driver contains the source code and Makefile for the drivers The directory examples holds the source code and Makefile for the example programs The directory include contains all header files used by the driver example programs library and your application programs Library source code and Makefile reside in the directory lib Building the Driver Driver source code uses files located in the kernel source tree Therefore you must have the full kernel source tree available in order to build the driver The kernel source tree consumes a lot of disk space on the order of 100 to 200 megabytes Because production systems rarely contain this much disk space you will probably use a development machine to compile the driver source code The development system which provides a full compil
44. y page into main memory from some device much slower than memory Your application can perform no useful work while it slumbers Process scheduling priority affects which process gets chosen to run on the CPU If your application has a scheduling priority lower than most other processes it will not be selected to run if at least one of the higher priority processes is ready to run Furthermore a runnable process with a scheduling priority lower than that of a running process cannot preempt that process and begin running on the CPU Other interrupts may affect an application A system s interrupt controller usually assigns a priority to each interrupt Thus a higher priority interrupt can interfere with the interrupt your application is interested in by keeping it pending until the higher priority interrupt is serviced Worse if several interrupts occur while one is being processed some of them may be lost The delays inherent in any of the above situations affect how quickly an application can respond to an interrupt and how many interrupts can be processed in a given period of time The application may miss or lose interrupts especially if interrupts occur quickly enough A board may enter an inconsistent state if interrupts are not acknowledged reasonably Improving Performance To address the number of runnable processes issue conduct an audit of the system and determine which processes you do not need For each such process some of the cha
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