BF537EthernetDeviceDriverDesign

BF537EthernetDeviceDriverDesign - BF537 Ethernet Device...

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BF537 Ethernet Device Driver Design Version 0.1 19 October 2004 BF537 Ethernet Device Driver Design ................................................................................ 1 Default configuration ....................................................................................................... 1 Memory allocation model ................................................................................................ 1 Receiving frames ............................................................................................................. 2 Transmitting frames ......................................................................................................... 4 Handling Ethernet event interrupts .................................................................................. 5 Handling of control commands ........................................................................................ 5 Default configuration The driver will collect the configuration information from the various ADI_ETHER_* commands until the ADI_ETHER_START is issued, at that point the driver will actually physically configure the MAC. The default configuration that the driver assumes is summarised below No checksum generation Receive frame word alignment active (to make TX and RX frame format the same). Always use large descriptors Reset all counters to zero Set counters to clear on a read Allow counters to saturate Enable the counters RMII mode with port configured at 100 Mbits/sec Half duplex Good frames, own address and broadcast address only The interrupt manager will be used to handle DMA interrupts and Ethernet event interrupts directly rather than using the DMA manager to exploit the availability of staud words to signal buffer completion. Memory allocation model In this model, the physical device driver does not perform any memory allocations. Buffers and any other storage required by the physical driver are supplied by the
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application (stack). The proposed driver model is designed to minimize the amount of copying of received and transmitted frames while minimizing the amount of memory needed to buffer received frames. Since the BF537 uses descriptor based DMA to transfer data between the MAC and the Blackfin, there are two kinds of memory allocations from the application that are required by the BF537 driver. 1. Memory areas that the driver uses to organize the required descriptor lists for both sending and receiving frames. 2. The actual buffers that contain the frame data received from or to be transmitted to the LAN and the associated buffer structure for each buffer. The memory for the DMA descriptors is supplied through the use of two control
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BF537EthernetDeviceDriverDesign - BF537 Ethernet Device...

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