[pci] Backup and restore standard config space across PCIe FLR

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/bus/pciextra.c

@@ -3,6 +3,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <stdint.h>
 #include <ipxe/timer.h>
 #include <ipxe/pci.h>
+#include <ipxe/pcibackup.h>
 
 static int pci_find_capability_common ( struct pci_device *pci,
 					uint8_t pos, int cap ) {
@@ -121,8 +122,12 @@ unsigned long pci_bar_size ( struct pci_device *pci, unsigned int reg ) {
  * @v exp		PCI Express Capability address
  */
 void pci_reset ( struct pci_device *pci, unsigned int exp ) {
+	struct pci_config_backup backup;
 	uint16_t control;
 
+	/* Back up configuration space */
+	pci_backup ( pci, &backup, PCI_CONFIG_BACKUP_STANDARD, NULL );
+
 	/* Perform a PCIe function-level reset */
 	pci_read_config_word ( pci, ( exp + PCI_EXP_DEVCTL ), &control );
 	control |= PCI_EXP_DEVCTL_FLR;
@@ -131,6 +136,6 @@ void pci_reset ( struct pci_device *pci, unsigned int exp ) {
 	/* Allow time for reset to complete */
 	mdelay ( PCI_EXP_FLR_DELAY_MS );
 
-	/* Re-enable device */
-	adjust_pci_device ( pci );
+	/* Restore configuration */
+	pci_restore ( pci, &backup, PCI_CONFIG_BACKUP_STANDARD, NULL );
 }