libqos: Better handling of PCI legacy IO

The usual model for PCI IO with libqos is to use qpci_iomap() to map a
specific BAR for a PCI device, then perform IOs within that BAR using
qpci_io_{read,write}*().

However, certain devices also have legacy PCI IO.  In this case, instead of
(or as well as) being accessed via PCI BARs, the device can be accessed
via certain well-known, fixed addresses in PCI IO space.

Two existing tests use legacy PCI IO, and take different flawed approaches
to it:
    * tco-test manually constructs a tco_io_base value instead of calling
      qpci_iomap(), which assumes internal knowledge of the structure of
      the value it shouldn't have
    * ide-test uses direct in*() and out*() calls instead of using
      qpci_io_*() accessors, meaning it's not portable to non-x86 machine
      types.

This patch implements a new qpci_iomap_legacy() interface which gets a
handle in the same format as qpci_iomap() but refers to a region in
the legacy PIO space.  For a device which has the same registers
available both in a BAR and in legacy space (quite common), this
allows the same test code to test both options with just a different
iomap() at the beginning.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>

tests/libqos/pci.c

@@ -350,6 +350,11 @@ void qpci_iounmap(QPCIDevice *dev, void *data)
     /* FIXME */
 }
 
+void *qpci_legacy_iomap(QPCIDevice *dev, uint16_t addr)
+{
+    return (void *)(uintptr_t)addr;
+}
+
 void qpci_plug_device_test(const char *driver, const char *id,
                            uint8_t slot, const char *opts)
 {

tests/libqos/pci.h

@@ -94,6 +94,7 @@ void qpci_io_writel(QPCIDevice *dev, void *data, uint32_t value);
 
 void *qpci_iomap(QPCIDevice *dev, int barno, uint64_t *sizeptr);
 void qpci_iounmap(QPCIDevice *dev, void *data);
+void *qpci_legacy_iomap(QPCIDevice *dev, uint16_t addr);
 
 void qpci_plug_device_test(const char *driver, const char *id,
                            uint8_t slot, const char *opts);