Calling the elstartlocked Routine | Compaq AA-RNG2A-TE guide

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Calls the simple_lock_try( ) routine to try to assert a lock with read and write access for the resource that is associated with the specified simple lock. The el_start( ) routine calls simple_lock_try( ) rather than simple_lock( ) because simple_lock_try( ) returns immediately if the resource is already locked; simple_lock( ) spins until the lock has been obtained. Make sure that you call simple_lock_try( ) when you need a simple lock but the code cannot spin until the lock is obtained.

In this example, simple_lock_try( ) was used as an optimization. If the simple lock is already held, then another thread is executing somewhere in the driver and is either currently servicing the transmit request queue or will service it soon. Therefore, the transmit request that was put on the send queue prior to calling the start interface will be handled shortly. In this case, the code does not need to wait for the lock (because someone else will do the transmit) and can return to the caller.

The argument to simple_lock_try( ) is a pointer to a simple lock data structure. The if_el device driver declares the simple lock data structure by calling the decl_simple_lock_data( ) routine, and it stores a pointer to this data structure in the el_softc data structure.

If the simple_lock_try( ) routine fails to assert the simple lock, calls the splx( ) routine to reset the CPU priority to the level that the s variable specifies, then returns. Otherwise, the simple lock was obtained.

9.1.2 Calling the el_start_locked Routine

The following code shows how the el_start( ) routine calls the el_start_locked( ) routine, which starts the transmit operation:

el_start_locked(sc, ifp);

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Calls the el_start_locked( ) routine, which performs the tasks that are related to the start operation.

9.1.3 Releasing the Simple Lock and Resetting the IPL

The following code shows how the el_start( ) routine releases the simple lock and resets the IPL.

simple_unlock(&sc->el_softc_lock);

splx(s); 2

}

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Calls the simple_unlock( ) routine to release a simple lock for the resource that is associated with the specified simple lock data structure.

9–2Implementing the Start Section

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Compaq AA-RNG2A-TE manual Calling the elstartlocked Routine, Releasing the Simple Lock and Resetting the IPL

Contents

December Product Version Compaq Computer Corporation Houston, TexasPage Contents Implementing the Configure Section Implementing the Autoconfiguration Support Section probe Implementing the Autoconfiguration Support Section attach Implementing the unattach Routine Implementing the Initialization Section Implementing the Start Section Implementing the Reset Section Implementing a Watchdog SectionImplementing the ioctl Section Network Device Driver Configuration Index Implementing the Interrupt Section Tables Page About This Manual Audience Scope of this Manual New and Changed Features Organization Related Documentation Examples Reader’s Comments Reference Pages Conventions That are used in driver configuration, these brackets Page Network Device Driver Environment Network Device Driver Include Files Section for a Network Driver Declarations Section for a Network Driver External and Forward Declarations Declaring softc and controller Data Structure Arrays Declaring and Initializing the driver Data Structure Defining Driver-Specific Macros 8Network Device Driver Environment Driver-Specific Macros MacroDescription Initialization Section for a Network Driver Configure Section for a Network DriverAutoconfiguration Support Section for a Network Driver Start Section for a Network Driver Ioctl Section for a Network Driver Reset Section for a Network DriverWatchdog Section for a Network Driver Interrupt Section for a Network Driver 12Network Device Driver Environment Defining Device Register Offsets Interrupt and Status Register Offset Definitions Command Port Register Offset Definitions Defining Device Register Offsets Window 0 Configuration Register Offset Definitions Register Constant W0CCR Defines the offset for the resource configuration register Window 3 Configuration Register Offset Definitions Window 3 Configuration Registers Window 1 Operational Register Offset Definitions Window 1 Operational Registers 10Defining Device Register Offsets Window 4 Diagnostic Register Offset Definitions Mdncrc 12Defining Device Register Offsets Eeprom Data Structure Definition Page Defining the softc Data Structure Shows a typical softc data structure Defining Common Information 2Defining the softc Data Structure Defining the softc Data Structure Enabling Support for Enhanced Hardware Management Defining Media State Information Media state has been determined Defining the Interrupt Handler ID Defining the Base RegisterDefining Multicast Table Information Defining CSR Pointer Information Defining Fifo Maintenance Information Defining Bus-Specific Information Defining Interrupt and Timeout Statistics Defining the Broadcast FlagDefining the Debug Flag Defining Autosense Kernel Thread Context Information Defining the Polling Context Flag Defining a Copy of the w3eeprom Data Structure Declaring the Simple Lock Data Structure Implementing the Configure Section Etc/sysconfigtab database Setting Up the elconfigure Routine Following code shows how to set up the elconfigure routine 4Implementing the Configure Section Implementing the Autoconfiguration Support Section probe Implementing the elprobe Routine Setting Up the elprobe Routine Following code shows how to set up the elprobe routine Implementing the Autoconfiguration Support Section probe 4Implementing the Autoconfiguration Support Section probe Performing Bus-Specific Tasks Implementing the Autoconfiguration Support Section probe 6Implementing the Autoconfiguration Support Section probe Allocating Memory for the softc Data Structure Allocating the etherdriver Data Structure Setting Bus-Specific Data Structure Members Computing the CSR Addresses Implementing the Autoconfiguration Support Section probe 10Implementing the Autoconfiguration Support Section probe Handling First-Time Probe Operations Implementing the Autoconfiguration Support Section probe 12Implementing the Autoconfiguration Support Section probe Handling Subsequent Probe Operations Implementing the Autoconfiguration Support Section probe Registering the Interrupt Handler Implementing the Autoconfiguration Support Section probe Saving the controller and softc Data Structure Pointers Trying to Allocate Another controller Data Structure Implementing the elshutdown Routine Implementing the elautosensethread RoutineRegistering the shutdown Routine 18Implementing the Autoconfiguration Support Section probe Setting Up the elautosensethread Routine Blocking Until Awakened Testing for the Termination Flag Starting Up StatisticsEntering the Packet Transmit Loop Using the Default from the ROM Saving Counters Prior to the Transmit OperationAllocating Memory for a Test Packet Setting the Media in the Hardware Building the Test PacketTransmitting the Test Packet Setting a Timer for the Current Kernel Thread Testing for Loss of Carrier Setting Up New Media Determining Whether Packets Were Transmitted SuccessfullyPrinting Debug Information Establishing the Media 26Implementing the Autoconfiguration Support Section probe Implementing the Autoconfiguration Support Section attach Setting Up the elattach Routine Initializing the Media Address and Media Header Lengths Setting Up the Media 4Implementing the Autoconfiguration Support Section attach Initializing Simple Lock Information Printing a Success Message Specifying the Network Driver Interfaces Signifies that the network interface supports Setting the Baud Rate Attaching to the Packet Filter and the Network Layer Setting Network Attributes and Registering the Adapter Handling the Reinsert Operation Enabling the Interrupt Handler Starting the Polling Process Setting Up the elunattach Routine Implementing the unattach Routine Verifying That the Interface Has Shut Down Obtaining the Simple Lock and Shutting Down the Device Disabling the Interrupt Handler Terminating the Autosense Kernel Thread Unregistering the Shutdown Routine Unregistering the Pcmcia Event Callback RoutineStopping the Polling Process Terminating the Simple Lock Unregistering the Card from the Hardware Management Database Freeing ResourcesPage Setting Up the elinit Routine Implementing the Initialization SectionImplementing the elinit Routine Setting the IPL and Obtaining the Simple Lock Determining Whether the Pcmcia Card Is Present Calling the elinitlocked Routine Releasing the Simple Lock and Resetting the IPLImplementing the elinitlocked Routine Returning the Status from the elinitlocked Routine Resetting the Transmitter and Receiver Clearing Interrupts Starting the Device Ensuring That the 10Base2 Transceiver Is Off Setting the LAN Media Setting a LAN Attribute Resetting the Transmitter and Receiver AgainSelecting Memory Mapping Setting the LAN Address Processing Special Flags Setting the Debug Flag Enabling TX and RX Setting the Operational Window Enabling InterruptsMarking the Device as Running Starting the Autosense Kernel Thread Starting the Transmit of Pending PacketsPage Implementing the Start Section Implementing the elstart Routine Calling the elstartlocked Routine Implementing the elstartlocked Routine 4Implementing the Start Section Implementing the Start Section Transmitting the Buffer Handlelongword Accounting for Outgoing Bytes Indicating When to Start the Watchdog Routine Setting the IPL and Obtaining the Simple Lock Implementing a Watchdog Section Releasing the Simple Lock and Resetting the IPL Implementing the Reset Section Implementing the elreset Routine Implementing the elresetlocked Routine Ioctl Command Required Description For More Information Implementing the ioctl Section Setting Up the elioctl Routine Following code shows how to set up the elioctl routine Setting the IPL and Obtaining the Simple Lock Enabling Loopback Mode Siocenablback ioctl Command Disabling Loopback Mode Siocdisablback ioctl Command Setting the Local MAC Address Siocsphysaddr ioctl Command 12-6Implementing the ioctl Section Implementing the ioctl Section Determines whether the cmd argument is Siocrdctrs or Bringing Up the Device Siocsifaddr ioctl Command Network Interface Counter Types Using Currently Set Flags Siocsifflags ioctl Command Setting the IP MTU Siocsipmtu ioctl CommandSetting the Media Speed Siocsmacspeed ioctl Command Resetting the Device Siocifreset ioctl Command Setting Device Characteristics Siocifsetchar ioctl Command 12-12Implementing the ioctl Section If lockon 1 simpleunlock&sc-elsoftclock splxs Return status Page Implementing the Interrupt Section Implementing the elintr Routine Rearming the Next Timeout Reading the Interrupt Status Processing Completed Receive and Transmit Operations Acknowledging the Interrupt Transmitting Pending Frames Indicating That the Interrupt Was Serviced Implementing the elrint Routine Pulling the Packets from the Fifo Buffer Examining the First Part of the Packet Copying the Received Packet into the mbuf 13-8Implementing the Interrupt Section Discarding a Packet Implementing the eltint Routine Counting the Transmit Interrupt Managing Excessive Data Collisions Writing to the Status Register to Obtain the Next Value Implementing the elerror Routine Queuing Other Transmits Network Device Driver Configuration Page Index Index-1 Declarations section, 1-4devdriver.h header file, 1-4device Index-2 Interrupt Index-3 Interrupt handler Index-4 Packet Index-5 ROM Index-6 Transmit Index-7