PCI: endpoint: Make *_free_bar() to return error codes on failure

Modify pci_epc_get_next_free_bar() and pci_epc_get_first_free_bar() to
return error values if there are no free BARs available.

Link: https://lore.kernel.org/r/20210201195809.7342-5-kishon@ti.comSigned-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>

drivers/pci/endpoint/functions/pci-epf-test.c

@@ -834,6 +834,8 @@ static int pci_epf_test_bind(struct pci_epf *epf)
 		linkup_notifier = epc_features->linkup_notifier;
 		core_init_notifier = epc_features->core_init_notifier;
 		test_reg_bar = pci_epc_get_first_free_bar(epc_features);
+		if (test_reg_bar < 0)
+			return -EINVAL;
 		pci_epf_configure_bar(epf, epc_features);
 	}
 

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

@@ -90,8 +90,8 @@ EXPORT_SYMBOL_GPL(pci_epc_get);
  * Invoke to get the first unreserved BAR that can be used by the 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)
+enum pci_barno
+pci_epc_get_first_free_bar(const struct pci_epc_features *epc_features)
 {
 	return pci_epc_get_next_free_bar(epc_features, BAR_0);
 }
@@ -105,13 +105,13 @@ EXPORT_SYMBOL_GPL(pci_epc_get_first_free_bar);
  * Invoke to get the next unreserved BAR starting from @bar that can be used
  * for endpoint function. For any incorrect value in reserved_bar return '0'.
  */
-unsigned int pci_epc_get_next_free_bar(const struct pci_epc_features
+enum pci_barno pci_epc_get_next_free_bar(const struct pci_epc_features
 					 *epc_features, enum pci_barno bar)
 {
 	unsigned long free_bar;
 
 	if (!epc_features)
-		return 0;
+		return BAR_0;
 
 	/* If 'bar - 1' is a 64-bit BAR, move to the next BAR */
 	if ((epc_features->bar_fixed_64bit << 1) & 1 << bar)
@@ -126,7 +126,7 @@ unsigned int pci_epc_get_next_free_bar(const struct pci_epc_features
 
 	free_bar = find_next_zero_bit(&free_bar, 6, bar);
 	if (free_bar > 5)
-		return 0;
+		return NO_BAR;
 
 	return free_bar;
 }

include/linux/pci-epc.h

@@ -201,9 +201,9 @@ 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);
-unsigned int pci_epc_get_next_free_bar(const struct pci_epc_features
+enum pci_barno
+pci_epc_get_first_free_bar(const struct pci_epc_features *epc_features);
+enum pci_barno pci_epc_get_next_free_bar(const struct pci_epc_features
 					 *epc_features, enum pci_barno bar);
 struct pci_epc *pci_epc_get(const char *epc_name);
 void pci_epc_put(struct pci_epc *epc);

include/linux/pci-epf.h

@@ -21,6 +21,7 @@ enum pci_notify_event {
 };
 
 enum pci_barno {
+	NO_BAR = -1,
 	BAR_0,
 	BAR_1,
 	BAR_2,