PCI software driver for Linux

Fedora is an impressive Linux release.
Microsoft should be worried...

Writing a Plug-and-Play PCI driver for Linux

It's actually easier than on Windows.

1. Create the init_module and cleanup_module

These functions are called when the driver is loaded or unloaded.

int init_module(void)
{
  return pci_module_init(&pci_driver_DevicePCI);
}

void cleanup_module(void)
{
  pci_unregister_driver(&pci_driver_DevicePCI);
}

The "pci_driver_DevicePCI" structure is shown next...

2. Create tables describing the PCI board

#define VENDOR_ID 0x1000
#define DEVICE_ID 0x0000

struct pci_device_id  pci_device_id_DevicePCI[] = 
{
  {VENDOR_ID, DEVICE_ID, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0},
  {}  // end of list
};

struct pci_driver  pci_driver_DevicePCI = 
{
  name: "MyPCIDevice",
  id_table: pci_device_id_DevicePCI,
  probe: device_probe,
  remove: device_remove
};

device_probe and device_remove are 2 callback functions, created next...

3. Create the "probe" and "remove" callbacks

int device_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
  int ret;
  ret = pci_enable_device(dev);
  if (ret < 0) return ret;

  ret = pci_request_regions(dev, "MyPCIDevice");
  if (ret < 0) 
  {
    pci_disable_device(dev);
    return ret;
  }

  return 0;
}

void device_remove(struct pci_dev *dev)
{
  pci_release_regions(dev);
  pci_disable_device(dev);
}

That should be enough to allocate the memory resource...
Thanks to Ian Johnston's help, I got the current files (for Fedora Core 2 - kernel 2.6) to compile.
Build them using "make" followed by "insmod DevicePCI.ko" to load the driver, and "rmmod DevicePCI.ko" to unload it.

Your turn to experiment!

Link

• The Linux Device Drivers, 2nd Edition Online Book, and in particular the "Handling Hot-Pluggable Devices" section of chapter 15.
• A nice Writing a PCI driver in 5+3 steps presentation

---

This page was last updated on November 07 2004.