[U-Boot] [RFC PATCH 07/29] drivers: pci-uclass: add support for Enhanced Allocation in Bridges

[Suneel Garapati]

From: Suneel Garapati <sgarap...@marvell.com>

If Enhanced Allocation capability is present in bridges, use it
to read the fixed sub-ordinate bus number.

Signed-off-by: Suneel Garapati <sgarap...@marvell.com>
---
 drivers/pci/pci-uclass.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index f17e83565c..51f7135723 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -599,10 +599,20 @@ int dm_pci_hose_probe_bus(struct udevice *bus)
 {
        int sub_bus;
        int ret;
+       int ea_pos;
+       u8 reg;
 
        debug("%s\n", __func__);
 
-       sub_bus = pci_get_bus_max() + 1;
+       ea_pos = dm_pci_find_capability(bus, PCI_CAP_ID_EA);
+
+       if (ea_pos) {
+               dm_pci_read_config8(bus, ea_pos + sizeof(u32) + sizeof(u8),
+                                   &reg);
+               sub_bus = reg;
+       } else {
+               sub_bus = pci_get_bus_max() + 1;
+       }
        debug("%s: bus = %d/%s\n", __func__, sub_bus, bus->name);
        dm_pciauto_prescan_setup_bridge(bus, sub_bus);
 
@@ -612,12 +622,15 @@ int dm_pci_hose_probe_bus(struct udevice *bus)
                      ret);
                return ret;
        }
-       if (sub_bus != bus->seq) {
-               printf("%s: Internal error, bus '%s' got seq %d, expected %d\n",
-                      __func__, bus->name, bus->seq, sub_bus);
-               return -EPIPE;
+
+       if (!ea_pos) {
+               if (sub_bus != bus->seq) {
+                       printf("%s: Internal error, bus '%s' got seq %d, 
expected %d\n",
+                              __func__, bus->name, bus->seq, sub_bus);
+                       return -EPIPE;
+               }
+               sub_bus = pci_get_bus_max();
        }
-       sub_bus = pci_get_bus_max();
        dm_pciauto_postscan_setup_bridge(bus, sub_bus);
 
        return sub_bus;
-- 
2.23.0

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