[SeaBIOS] [RFC PATCH 2/2] pci: enable RedHat pci bridges to reserve more buses

[Aleksandr Bezzubikov]

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

Signed-off-by: Aleksandr Bezzubikov 
---
 src/fw/pciinit.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/fw/pciinit.c b/src/fw/pciinit.c
index 08221e6..b6f3a01 100644
--- a/src/fw/pciinit.c
+++ b/src/fw/pciinit.c
@@ -578,9 +578,17 @@ pci_bios_init_bus_rec(int bus, u8 *pci_bus)
         pci_bios_init_bus_rec(secbus, pci_bus);

if (subbus != *pci_bus) {
+            u16 vendor = pci_config_readw(bdf, PCI_VENDOR_ID);
+            u8 res_bus = 0;
+            if (vendor == 0x1b36) {
+                u8 cap = pci_find_capability_bdf(bdf, PCI_CAP_ID_VNDR, 0);
+                if (cap) {
+                    res_bus = pci_config_readb(bdf, cap + 16);
+                }
+            }
             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);
         }