1. Some platforms do not support interrupt mode (PCI_MSI/MSIX),
so add polling mode support, so these platforms can also use virtio-pci;
2. In some cases, we do not want to use the interrupt for virtio driver
to avoid time jitter, so add the polling mode support;
3. If CONFIG_DRIVERS_VIRTIO_PCI_POLLING_PERIOD <= 0, interrupt mode.
if CONFIG_DRIVERS_VIRTIO_PCI_POLLING_PERIOD > 0, polling mode.
Signed-off-by: wangyongrong <wangyongrong@xiaomi.com>
Follow the virtio spec, support the virtio pci Legacy
Signed-off-by: wangyongrong <wangyongrong@xiaomi.com>
Signed-off-by: andi <andi6@xiaomi.com>
Signed-off-by: Bowen Wang <wangbowen6@xiaomi.com>
