scsi: aic79xx: Use generic power management

Drivers should do only device-specific jobs. But in general, drivers using
legacy PCI PM framework for .suspend()/.resume() have to manage many PCI
PM-related tasks themselves which can be done by PCI Core itself. This
brings extra load on the driver and it directly calls PCI helper functions
to handle them.

Switch to the new generic framework by updating function signatures and
define a "struct dev_pm_ops" variable to bind PM callbacks. Also, remove
unnecessary calls to the PCI Helper functions along with the legacy
.suspend & .resume bindings.

Link: https://lore.kernel.org/r/20201102164730.324035-8-vaibhavgupta40@gmail.com
Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/aic7xxx/aic79xx.h

@@ -1330,10 +1330,8 @@ const struct	ahd_pci_identity *ahd_find_pci_device(ahd_dev_softc_t);
 int			  ahd_pci_config(struct ahd_softc *,
 					 const struct ahd_pci_identity *);
 int	ahd_pci_test_register_access(struct ahd_softc *);
-#ifdef CONFIG_PM
-void	ahd_pci_suspend(struct ahd_softc *);
-void	ahd_pci_resume(struct ahd_softc *);
-#endif
+void __maybe_unused	ahd_pci_suspend(struct ahd_softc *);
+void __maybe_unused	ahd_pci_resume(struct ahd_softc *);
 
 /************************** SCB and SCB queue management **********************/
 void		ahd_qinfifo_requeue_tail(struct ahd_softc *ahd,
@@ -1344,10 +1342,8 @@ struct ahd_softc	*ahd_alloc(void *platform_arg, char *name);
 int			 ahd_softc_init(struct ahd_softc *);
 void			 ahd_controller_info(struct ahd_softc *ahd, char *buf);
 int			 ahd_init(struct ahd_softc *ahd);
-#ifdef CONFIG_PM
-int			 ahd_suspend(struct ahd_softc *ahd);
-void			 ahd_resume(struct ahd_softc *ahd);
-#endif
+int __maybe_unused	 ahd_suspend(struct ahd_softc *ahd);
+void __maybe_unused	 ahd_resume(struct ahd_softc *ahd);
 int			 ahd_default_config(struct ahd_softc *ahd);
 int			 ahd_parse_vpddata(struct ahd_softc *ahd,
 					   struct vpd_config *vpd);

drivers/scsi/aic7xxx/aic79xx_core.c

@@ -7866,11 +7866,9 @@ ahd_pause_and_flushwork(struct ahd_softc *ahd)
 	ahd->flags &= ~AHD_ALL_INTERRUPTS;
 }
 
-#ifdef CONFIG_PM
-int
+int __maybe_unused
 ahd_suspend(struct ahd_softc *ahd)
 {
-
 	ahd_pause_and_flushwork(ahd);
 
 	if (LIST_FIRST(&ahd->pending_scbs) != NULL) {
@@ -7881,15 +7879,13 @@ ahd_suspend(struct ahd_softc *ahd)
 	return (0);
 }
 
-void
+void __maybe_unused
 ahd_resume(struct ahd_softc *ahd)
 {
-
 	ahd_reset(ahd, /*reinit*/TRUE);
 	ahd_intr_enable(ahd, TRUE); 
 	ahd_restart(ahd);
 }
-#endif
 
 /************************** Busy Target Table *********************************/
 /*

drivers/scsi/aic7xxx/aic79xx_osm_pci.c

@@ -74,11 +74,10 @@ static const struct pci_device_id ahd_linux_pci_id_table[] = {
 
 MODULE_DEVICE_TABLE(pci, ahd_linux_pci_id_table);
 
-#ifdef CONFIG_PM
-static int
-ahd_linux_pci_dev_suspend(struct pci_dev *pdev, pm_message_t mesg)
+static int __maybe_unused
+ahd_linux_pci_dev_suspend(struct device *dev)
 {
-	struct ahd_softc *ahd = pci_get_drvdata(pdev);
+	struct ahd_softc *ahd = dev_get_drvdata(dev);
 	int rc;
 
 	if ((rc = ahd_suspend(ahd)))
@@ -86,39 +85,20 @@ ahd_linux_pci_dev_suspend(struct pci_dev *pdev, pm_message_t mesg)
 
 	ahd_pci_suspend(ahd);
 
-	pci_save_state(pdev);
-	pci_disable_device(pdev);
-
-	if (mesg.event & PM_EVENT_SLEEP)
-		pci_set_power_state(pdev, PCI_D3hot);
-
 	return rc;
 }
 
-static int
-ahd_linux_pci_dev_resume(struct pci_dev *pdev)
+static int __maybe_unused
+ahd_linux_pci_dev_resume(struct device *dev)
 {
-	struct ahd_softc *ahd = pci_get_drvdata(pdev);
-	int rc;
-
-	pci_set_power_state(pdev, PCI_D0);
-	pci_restore_state(pdev);
-
-	if ((rc = pci_enable_device(pdev))) {
-		dev_printk(KERN_ERR, &pdev->dev,
-			   "failed to enable device after resume (%d)\n", rc);
-		return rc;
-	}
-
-	pci_set_master(pdev);
+	struct ahd_softc *ahd = dev_get_drvdata(dev);
 
 	ahd_pci_resume(ahd);
 
 	ahd_resume(ahd);
 
-	return rc;
+	return 0;
 }
-#endif
 
 static void
 ahd_linux_pci_dev_remove(struct pci_dev *pdev)
@@ -224,13 +204,14 @@ ahd_linux_pci_dev_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	return (0);
 }
 
+static SIMPLE_DEV_PM_OPS(ahd_linux_pci_dev_pm_ops,
+			 ahd_linux_pci_dev_suspend,
+			 ahd_linux_pci_dev_resume);
+
 static struct pci_driver aic79xx_pci_driver = {
 	.name		= "aic79xx",
 	.probe		= ahd_linux_pci_dev_probe,
-#ifdef CONFIG_PM
-	.suspend	= ahd_linux_pci_dev_suspend,
-	.resume		= ahd_linux_pci_dev_resume,
-#endif
+	.driver.pm	= &ahd_linux_pci_dev_pm_ops,
 	.remove		= ahd_linux_pci_dev_remove,
 	.id_table	= ahd_linux_pci_id_table
 };

drivers/scsi/aic7xxx/aic79xx_pci.c

@@ -377,8 +377,7 @@ ahd_pci_config(struct ahd_softc *ahd, const struct ahd_pci_identity *entry)
 	return ahd_pci_map_int(ahd);
 }
 
-#ifdef CONFIG_PM
-void
+void __maybe_unused
 ahd_pci_suspend(struct ahd_softc *ahd)
 {
 	/*
@@ -394,7 +393,7 @@ ahd_pci_suspend(struct ahd_softc *ahd)
 
 }
 
-void
+void __maybe_unused
 ahd_pci_resume(struct ahd_softc *ahd)
 {
 	ahd_pci_write_config(ahd->dev_softc, DEVCONFIG,
@@ -404,7 +403,6 @@ ahd_pci_resume(struct ahd_softc *ahd)
 	ahd_pci_write_config(ahd->dev_softc, CSIZE_LATTIME,
 			     ahd->suspend_state.pci_state.csize_lattime, /*bytes*/1);
 }
-#endif
 
 /*
  * Perform some simple tests that should catch situations where