PCI: endpoint: Make *_get_first_free_bar() take into account 64 bit BAR

[ Upstream commit 959a48d ]

pci_epc_get_first_free_bar() uses only "reserved_bar" member in
epc_features to get the first unreserved BAR. However if the reserved BAR
is also a 64-bit BAR, then the next BAR shouldn't be returned (since 64-bit
BAR uses two BARs).

Make pci_epc_get_first_free_bar() take into account 64 bit BAR while
returning the first free unreserved BAR.

Link: https://lore.kernel.org/r/20210201195809.7342-3-kishon@ti.com
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/pci/endpoint/pci-epc-core.c

@@ -93,12 +93,20 @@ EXPORT_SYMBOL_GPL(pci_epc_get);
 unsigned int pci_epc_get_first_free_bar(const struct pci_epc_features
 					*epc_features)
 {
-	int free_bar;
+	unsigned long free_bar;
 
 	if (!epc_features)
 		return 0;
 
-	free_bar = ffz(epc_features->reserved_bar);
+	/* Find if the reserved BAR is also a 64-bit BAR */
+	free_bar = epc_features->reserved_bar & epc_features->bar_fixed_64bit;
+
+	/* Set the adjacent bit if the reserved BAR is also a 64-bit BAR */
+	free_bar <<= 1;
+	free_bar |= epc_features->reserved_bar;
+
+	/* Now find the free BAR */
+	free_bar = ffz(free_bar);
 	if (free_bar > 5)
 		return 0;