PCI: PCIe AER: Introduce pci_aer_available()

Introduce a function allowing the caller to check whether to try to
enable PCIe AER.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/pci.h

@@ -140,8 +140,10 @@ static inline void pci_msi_init_pci_dev(struct pci_dev *dev) { }
 
 #ifdef CONFIG_PCIEAER
 void pci_no_aer(void);
+bool pci_aer_available(void);
 #else
 static inline void pci_no_aer(void) { }
+static inline bool pci_aer_available(void) { return false; }
 #endif
 
 static inline int pci_no_d1d2(struct pci_dev *dev)

drivers/pci/pcie/aer/aerdrv.c

@@ -72,6 +72,11 @@ void pci_no_aer(void)
 	pcie_aer_disable = 1;	/* has priority over 'forceload' */
 }
 
+bool pci_aer_available(void)
+{
+	return !pcie_aer_disable && pci_msi_enabled();
+}
+
 static int set_device_error_reporting(struct pci_dev *dev, void *data)
 {
 	bool enable = *((bool *)data);
@@ -411,9 +416,7 @@ static void aer_error_resume(struct pci_dev *dev)
  */
 static int __init aer_service_init(void)
 {
-	if (pcie_aer_disable)
-		return -ENXIO;
-	if (!pci_msi_enabled())
+	if (!pci_aer_available())
 		return -ENXIO;
 	return pcie_port_service_register(&aerdriver);
 }