[U-Boot] [RFC PATCH 10/29] drivers: pci-uclass: Add support for Alternate-RoutingID capability

[Suneel Garapati <suneelglinux@gmail.com>]

From: Suneel Garapati <sgarapati@marvell.com>

If ARI capability is found on device, use it to update next function
number in bus scan and also helps to skip unnecessary bdf scans.

Signed-off-by: Suneel Garapati <sgarapati@marvell.com>
---
 drivers/pci/pci-uclass.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index f9823231b1..b02588b552 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -773,7 +773,7 @@ int pci_bind_bus_devices(struct udevice *bus)
 	ulong header_type;
 	pci_dev_t bdf, end;
 	bool found_multi;
-	int ret;
+	int ret, ari_off;
 
 	found_multi = false;
 	end = PCI_BDF(bus->seq, PCI_MAX_PCI_DEVICES - 1,
@@ -846,6 +846,22 @@ int pci_bind_bus_devices(struct udevice *bus)
 		pplat->vendor = vendor;
 		pplat->device = device;
 		pplat->class = class;
+
+		ari_off = dm_pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI);
+		if (ari_off) {
+			u16 ari_cap;
+
+			/* Read Next Function number in ARI Cap Register */
+			dm_pci_read_config16(dev, ari_off + 4, &ari_cap);
+			/* Update next scan on this function number,
+			 * subtract 1 in BDF to satisfy loop increment.
+			 */
+			if (ari_cap & 0xff00) {
+				bdf = PCI_BDF(PCI_BUS(bdf), PCI_DEV(ari_cap),
+					      PCI_FUNC(ari_cap));
+				bdf = bdf - 0x100;
+			}
+		}
 	}
 
 	return 0;
-- 
2.23.0