PCI: endpoint: Add helper to get first unreserved BAR

Add a helper function pci_epc_get_first_free_bar() to get the first
unreserved BAR that can be used for endpoint function.
Tested-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

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

@@ -83,6 +83,29 @@ struct pci_epc *pci_epc_get(const char *epc_name)
 }
 EXPORT_SYMBOL_GPL(pci_epc_get);
 
+/**
+ * pci_epc_get_first_free_bar() - helper to get first unreserved BAR
+ * @epc_features: pci_epc_features structure that holds the reserved bar bitmap
+ *
+ * Invoke to get the first unreserved BAR that can be used for endpoint
+ * function. For any incorrect value in reserved_bar return '0'.
+ */
+unsigned int pci_epc_get_first_free_bar(const struct pci_epc_features
+					*epc_features)
+{
+	int free_bar;
+
+	if (!epc_features)
+		return 0;
+
+	free_bar = ffz(epc_features->reserved_bar);
+	if (free_bar > 5)
+		return 0;
+
+	return free_bar;
+}
+EXPORT_SYMBOL_GPL(pci_epc_get_first_free_bar);
+
 /**
  * pci_epc_get_features() - get the features supported by EPC
  * @epc: the features supported by *this* EPC device will be returned

include/linux/pci-epc.h

@@ -180,6 +180,8 @@ int pci_epc_start(struct pci_epc *epc);
 void pci_epc_stop(struct pci_epc *epc);
 const struct pci_epc_features *pci_epc_get_features(struct pci_epc *epc,
 						    u8 func_no);
+unsigned int pci_epc_get_first_free_bar(const struct pci_epc_features
+					*epc_features);
 struct pci_epc *pci_epc_get(const char *epc_name);
 void pci_epc_put(struct pci_epc *epc);