[SeaBIOS] [RFC PATCH v2 4/4] pci: enable RedHat PCI bridges to reserve additional buses on PCI init

[Aleksandr Bezzubikov]

In case of Red Hat PCI bridges reserve additional buses, which number is provided
in a vendor-specific capability.

Signed-off-by: Aleksandr Bezzubikov 
---
 src/fw/pciinit.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/fw/pciinit.c b/src/fw/pciinit.c
index 864954f..f05a8b9 100644
--- a/src/fw/pciinit.c
+++ b/src/fw/pciinit.c
@@ -15,6 +15,7 @@
 #include "hw/pcidevice.h" // pci_probe_devices
 #include "hw/pci_ids.h" // PCI_VENDOR_ID_INTEL
 #include "hw/pci_regs.h" // PCI_COMMAND
+#include "hw/pci_cap.h" // qemu_pci_cap
 #include "list.h" // struct hlist_node
 #include "malloc.h" // free
 #include "output.h" // dprintf
@@ -578,9 +579,18 @@ pci_bios_init_bus_rec(int bus, u8 *pci_bus)
         pci_bios_init_bus_rec(secbus, pci_bus);

if (subbus != *pci_bus) {
+            u8 res_bus = 0;
+            if (pci_config_readw(bdf, PCI_VENDOR_ID) == PCI_VENDOR_ID_REDHAT) {
+                u8 cap = pci_find_capability(bdf, PCI_CAP_ID_VNDR, 0);
+                if (cap) {
+                    res_bus = pci_config_readb(bdf,
+                            cap + offsetof(struct redhat_pci_bridge_cap,
+                                           bus_res));
+                }
+            }
             dprintf(1, "PCI: subordinate bus = 0x%x -> 0x%x\n",
-                    subbus, *pci_bus);
-            subbus = *pci_bus;
+                    subbus, *pci_bus + res_bus);
+            subbus = *pci_bus + res_bus;
         } else {
             dprintf(1, "PCI: subordinate bus = 0x%x\n", subbus);
         }