VxWorks Reference Manual : Libraries
ei82596End - END style Intel 82596 Ethernet network interface driver
ei82596EndLoad( ) - initialize the driver and device
This module implements an Intel 82596 Ethernet network interface driver. This driver is designed to be moderately generic. It operates unmodified across the range of architectures and targets supported by VxWorks. To achieve this, this driver requires some external support routines as well as several target-specific parameters. These parameters (and the mechanisms used to communicate them to the driver) are detailed below.
This driver can run with the device configured in either big-endian or little-endian modes. Error recovery code has been added to deal with some of the known errata in the A0 version of the device. This driver supports up to four individual units per CPU.
This device is on-board. No jumpering diagram is necessary.
The driver provides one standard external interface, ei82596EndLoad( ). As input, this routine takes a string of colon-separated parameters. The parameters should be specified in hexadecimal (optionally preceded by "0x" or a minus sign "-"). The parameter string is parsed using strtok_r( ), and each parameter is converted from string to binary by a call to:
strtoul(parameter, NULL, 16).
The format of the parameter string is:
unit:ivec:sysbus:memBase:nTfds:nRfds:offset
- unit
- A convenient holdover from the former model. It is only used in the string name for the driver.
- ivec
- This is the interrupt vector number of the hardware interrupt generated by this ethernet device. The driver uses intConnect( ) to attach an interrupt handler to this interrupt.
- sysbus
- This parameter tells the device about the system bus. To determine the correct value for a target, see Intel 32-bit Local Area Network (LAN) Component User's Manual.
- memBase
- This parameter specifies the base address of a DMA-able cache-free pre-allocated memory region for use as a memory pool for transmit/receive descriptors, buffers, and other device control structures. If there is no pre-allocated memory available for the driver, this parameter should be -1 (NONE). In which case, the driver calls cacheDmaAlloc( ) to allocate cache-safe memory.
- nTfds
- This parameter specifies the number of transmit descriptor/buffers to be allocated. If this parameter is zero or -1 (NULL), a default of 32 is used.
- nRfds
- This parameter specifies the number of receive descriptor/buffers to be allocated. If this parameter is zero or -1 (NULL), a default of 32 is used.
- offset
- Specifies the memory alignment offset.
This driver requires seven external support functions:
- sys596IntEnable( )
- sys596IntDisable( )
- sysEnetAddrGet( )
- sys596Init( )
- sys596Port( )
- sys596ChanAtn( )
- sys596IntAck( )
The driver uses cacheDmaMalloc( ) to allocate memory to share with the 82596. The fixed-size pieces in this area total 160 bytes. The variable-size pieces in this area are affected by the configuration parameters specified in the eiattach( ) call. The size of one RFD (Receive Frame Descriptor) is 1536 bytes. The size of one TFD (Transmit Frame Descriptor) is 1534 bytes. For more on RFDs and TFDs, see the Intel 82596 User's Manual.
The 82596 requires ether that this shared memory region is non-cacheable or that the hardware implements bus snooping. The driver cannot maintain cache coherency for the device. This is because fields within the command structures are asynchronously modified by both the driver and the device, and these fields might share the same cache line.
The only adjustable parameters are the number of TFDs and RFDs that are created at run-time. These parameters are given to the driver when eiattach( ) is called. There is one TFD and one RFD associated with each transmitted frame and each received frame respectively. For memory-limited applications, decreasing the number of TFDs and RFDs might be a good idea. Increasing the number of TFDs provides no performance benefit after a certain point. Increasing the number of RFDs provides more buffering before packets are dropped. This can be useful if there are tasks running at a higher priority than the net task.
ei82596End, ifLib, Intel 82596 User's Manual, Intel 32-bit Local Area Network (LAN) Component User's Manual
ei82596EndLoad( ) - initialize the driver and device
END_OBJ *ei82596EndLoad ( char * initString /* parameter string */ )
This routine initializes both driver and device to an operational state using the device-specific values specified by initString. The initString parameter expects an ordered list of colon-separated values.
The format of the initString is:
unit:ivec:sysbus:memBase:nTfds:nRfds
- unit
- Specifies the unit number for this device.
- ivec
- This is the interrupt vector number of the hardware interrupt generated by this Ethernet device. The driver uses intConnect( ) to attach an interrupt handler for this interrupt.
- sysbus
- Passes in values as described in the Intel manual for the 82596. A default number of transmit/receive frames of 32 can be selected by passing zero in the parameters nTfds and nRfds. In other cases, the number of frames selected should be greater than two.
- memBase
- Informs the driver about the shared memory region. The 82596 shares a region of memory with the driver. The caller of this routine can specify the address of this memory region, or can specify that the driver must obtain this memory region from the system resources. If this parameter is set to the constant "NONE", this routine tries to allocate the shared memory from the system. Any other value for this parameter is interpreted by this routine as the address of the shared memory region to be used.
If the caller provides the shared memory region, the driver assumes that this region does not require cache-coherency operations, nor does it require conversions between virtual and physical addresses. If the caller indicates that this routine must allocate the shared memory region, this routine uses cacheDmaMalloc( ) to obtain some non-cacheable memory. The attributes of this memory are checked, and, if the memory is not both read- and write-coherent, this routine aborts.
An END object pointer or NULL.
ei82596End, ifLib, Intel 82596 User's Manual