I would recommend taking one of the Avnet/Xilinx one-day EDK classes (On Ramp) that are offered from time to time if you are a qualified Avnet account. Search avnet's website for OnRamp sessions for Xilinx and look for EDK.
Briefly, the steps to using GPIO or any of the Xilinx IP are as follows:
1. You need to be in the XPS tool with your project open.
2. On the left most panel, you will see an area called the "Project Information Area." There should be three tabs under this: "Project," "Applications," and "IP Catalog." All of the pre-included Xilinx IP such as Microblaze, GPIO, SPI, I2C, etc. are in the IP Catalog Tab. Click the "IP Catalog" Tab
3. If not expanded, click on the "EDK Install" plus (+) sign to expand this list. You should see a list of IP components that you can add to your design. You have likely already added a processor (PPC or Microblaze depending on your part). These are on the "Processor" line. You are looking for GPIO and it is on the "General Purpose IO" line. Click the plus (+) to the left of this line.
4. a line with a green star should appear that says "XPS General Purpose IO." You should right-click this line and select "Add IP"
5. The panel to the right has tabs on the bottom and the top. Select "System Assembly View" on the bottom tab. This allows you to review your hardware configuration (in the FPGA)
6. On the top, select "Bus Interfaces"
7. You should see a new line called "xps_gpio" or something similar. Click the plus (+) next to it to expand its ports
8. Be sure that your PLB bus is selected in the drop-down box to the right of SPLB -- this will connect your GPIO device to the PLB in the FPGA and allow your processor to talk to it
9. Right-click the xps_gpio line and select "Configure IP"
10. A panel will appear and you will need to select how many IO lines you need. This is fairly self explanatory. Note that you will have to connect each of these IO lines to an internal port (from some other HDL) or to a pin on the part. If you need more than 16 lines, enable channel #2. If you need more than 32 lines, add a second GPIO device as you did in step #5
11. Close the configure IP dialog
12. Click "Addresses" tab
13. On the far right, you will see a button labeled "Generate Addresses" -- this will generate an address in memory of your processor for the GPIO device. Click this button
14. You may now re-synthesize your XPS project into hardware
To actually use the device, you will need to go to the SDK and Synchronize with Hardware (this will add the driver to your software project). Then you can use the API reference and examples you find on the web to call it in software.
I've tried to make this as simple as I can, and once you are familiar with EDK (XPS + SDK) this is a real cake-walk. But when you first use the tools, you are going to feel like it's the most complicated thing on the planet. This is why I would recommend going to an on-ramp if you can. I went through all this last year -- from knowing nothing to being an EDK afficianado and it's a rough road. I will say, however, that the tools are very powerful and really automate the construction of an embedded system once you learn them.
Good luck.
Steve
