spapr_pci: Introduce a liobn number generating macros

We are going to have multiple DMA windows per PHB and we want them to
migrate so we need a predictable way of assigning LIOBNs.

This introduces a macro which makes up a LIOBN from fixed prefix,
PHB index (unique PHB id) and window number.

This introduces a SPAPR_PCI_DMA_WINDOW_NUM() to know the window number
from LIOBN. It is used to distinguish the default 32bit windows from
dynamic windows and avoid picking default DMA window properties from
a wrong TCE table.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>

include/hw/ppc/spapr.h

diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index af71e8b..9a9bb90 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -482,7 +482,9 @@
 #define SPAPR_TCE_PAGE_MASK    (SPAPR_TCE_PAGE_SIZE - 1)
 
 #define SPAPR_VIO_BASE_LIOBN    0x00000000
-#define SPAPR_PCI_BASE_LIOBN    0x80000000
+#define SPAPR_PCI_LIOBN(phb_index, window_num) \
+    (0x80000000 | ((phb_index) << 8) | (window_num))
+#define SPAPR_PCI_DMA_WINDOW_NUM(liobn) ((liobn) & 0xff)
 
 #define RTAS_ERROR_LOG_MAX      2048