Re: [PATCH 1/6] virtio interace

[Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>]

On Friday 21 September 2007, Rusty Russell wrote:
> Hmm, I guess we could have a PCI driver which claims all VIRTIO vendor
> devices.  

yes, that was the idea.

> Then it can call virtio_find_driver() (?) at the top of its 
> probe function to find if there's a matching virtio driver.  
> This PCI  driver would have to be initialized after all the virtio
> drivers are registered, but that's easy.

No, just use the driver model, instead of working against it:

struct pci_virtio_device {
	struct pci_dev *pdev;
	char __iomem *mmio_space;
	struct virtio_device vdev;
};

static int __devinit pci_virtio_probe(struct pci_dev *pdev,
				const struct pci_device_id *ent)
{
	struct pci_virtio_device *dev = kzalloc(sizeof (*dev), GFP_KERNEL);
	dev->pdev = pdev;
	dev->mmio_space = pcim_iomap(pdev, 0, PCI_VIRTIO_BUFSIZE);
	dev->vdev->ops = &pci_virtqueue_ops;
	dev->vdev->config = &pci_virtio_config_ops;
	dev->vdev->type = ent->device;
	dev->vdev->class = ent->class;
	dev->vdev.dev.parent = &pdev->dev;

	return virtio_device_register(&dev->vdev;
}

> The virtio layer would simply maintain a linked list of drivers and
> implement the virtio_find_driver() matching function.

nonono, just a virtio_bus that all virtio drivers register to:

static int virtio_net_probe(struct device *dev)
{
	struct virtio_device *vdev = to_virtio_dev(dev);
	struct virtqueue_ops *vq_ops = vdev->ops;

	/* same as current code */
	...

	return 0;
}

static struct virtio_device_id virtio_net_ids[] = {
	{ .type = VIRTIO_ID_NET, .class = PCI_CLASS_NETWORK_OTHER },
	{ },
};

static struct virtio_driver virtio_net = {
	.id_table = &virtio_net_ids,
	.driver = {
		.name = "virtionet",
		.probe = virtio_net_probe,
		.remove = virtionet_remove,
		.bus = &virtio_bus,        /* <- look here */
	},
};

static int __init virtio_net_init(void)
{
	return driver_register(&virtio_net.driver);
}
module_init(virtio_net_init);

> And since we've suppressed normal PCI driver request_module (since it
> always finds "the driver") then we can implement that in
> virtio_find_driver(), and not use a PCI MODULE_DEVICE_TABLE.  Then we
> don't need (full) PCI ids at all.

right, as shown in my example above.

	Arnd <><

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