• Johannes Berg's avatar
    um: add PCI over virtio emulation driver · 68f5d3f3
    Johannes Berg authored
    To support testing of PCI/PCIe drivers in UML, add a PCI bus
    support driver. This driver uses virtio, which in UML is really
    just vhost-user, to talk to devices, and adds the devices to
    the virtual PCI bus in the system.
    Since virtio already allows DMA/bus mastering this really isn't
    all that hard, of course we need the logic_iomem infrastructure
    that was added by a previous patch.
    The protocol to talk to the device is has a few fairly simple
    messages for reading to/writing from config and IO spaces, and
    messages for the device to send the various interrupts (INT#,
    MSI/MSI-X and while suspended PME#).
    Note that currently no offical virtio device ID is assigned for
    this protocol, as a consequence this patch requires defining it
    in the Kconfig, with a default that makes the driver refuse to
    work at all.
    Finally, in order to add support for MSI/MSI-X interrupts, some
    small changes are needed in the UML IRQ code, it needs to have
    more interrupts, changing NR_IRQS from 64 to 128 if this driver
    is enabled, but not actually use them for anything so that the
    generic IRQ domain/MSI infrastructure can allocate IRQ numbers.
    Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
    Signed-off-by: default avatarRichard Weinberger <richard@nod.at>