Xilinx UG492 Clock Slave, Software System Integration, Driver Instantiation, Software Drivers

Chapter 13: Software Drivers

Clock Slave

If the core is acting as a clock slave, the local RTC is closely matched to the value and frequency of the network clock master. This is achieved, in part, by receiving the PTP Sync and Follow-Upframes transmitted across the network by the clock master (and containing the sampled RTC value of the master). The PTP mechanism also tracks the total routing delay across the network between the clock master and itself. The software drivers use this data, in conjunction with recent historical data, to calculate the error between its local RTC counter and that of the RTC clock master. The software then periodically calculates an RTC correction value and an updated increment rate, and these values are written to appropriate RTC configuration registers.

Because the drivers are provided as C code text files, they can be easily modified and designers can edit the files to provide their own secret source, or even to update the software drivers for P802.1AS specification changes.

Software System Integration

The software drivers for the Ethernet AVB Endpoint core need to be run on an embedded processor. In addition, they require instantiation into the overall software project, and then initialization.

An example software project file that performs the required steps is included with the core in the following location:

<component_name>/MyProcessorIPLib/drivers/

ethernet_avb_endpoint_v2_04_a/examples/xavb_example.c

This software example has been tested in a real system. For this reason, use this file for reference, along with the following descriptions:

•“Driver Instantiation”

•“Interrupt Service Routine Connections”

•“Core Initialization”

•“Ethernet AVB Endpoint Setup”

•“Starting and Stopping the AVB Drivers”

Note: Unless you are already familiar with the Xilinx Embedded Development Kit (EDK), see the EDK documentation to follow the steps described.

Driver Instantiation

Software driver instantiation for the Ethernet AVB Endpoint core follows the standard EDK model used for all EDK IP cores and as recommended for all user defined pcores (see the EDK documentation). Initialization of the driver requires that an instance of the driver is instantiated, assigned a base address within the PLB address range, and configured using the standardized cores CfgInitialize function.

132	www.xilinx.com	Ethernet AVB Endpoint User Guide
		UG492 July 23, 2010