uio: add generic driver for PCI 2.3 devices

This adds a generic uio driver that can bind to any PCI device.  First
user will be virtualization where a qemu userspace process needs to give
guest OS access to the device.

Interrupts are handled using the Interrupt Disable bit in the PCI
command register and Interrupt Status bit in the PCI status register.
All devices compliant to PCI 2.3 (circa 2002) and all compliant PCI
Express devices should support these bits.  Driver detects this support,
and won't bind to devices which do not support the Interrupt Disable Bit
in the command register.

It's expected that more features of interest to virtualization will be
added to this driver in the future. Possibilities are: mmap for device
resources, MSI/MSI-X, eventfd (to interface with kvm), iommu.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Chris Wright <chrisw@redhat.com>
Signed-off-by: Hans J. Koch <hjk@linutronix.de>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/pci_regs.h b/include/linux/pci_regs.h
index fcaee42c7ac2..dd0bed4f1cf0 100644
--- a/include/linux/pci_regs.h
+++ b/include/linux/pci_regs.h
@@ -42,6 +42,7 @@
 #define  PCI_COMMAND_INTX_DISABLE 0x400 /* INTx Emulation Disable */
 
 #define PCI_STATUS              0x06    /* 16 bits */
+#define  PCI_STATUS_INTERRUPT   0x08    /* Interrupt status */
 #define  PCI_STATUS_CAP_LIST    0x10    /* Support Capability List */
 #define  PCI_STATUS_66MHZ       0x20    /* Support 66 Mhz PCI 2.1 bus */
 #define  PCI_STATUS_UDF         0x40    /* Support User Definable Features [obsolete] */