ptp_pch: use generic power management

With legacy PM, drivers themselves were responsible for managing the
device's power states and takes care of register states.

After upgrading to the generic structure, PCI core will take care of
required tasks and drivers should do only device-specific operations.

In the case of ptp_pch, after removing PCI helper functions, .suspend()
and .resume() became empty-body functions. Hence, define them NULL and
use dev_pm_ops.

Compile-tested only.

Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/ptp/ptp_pch.c

@@ -508,40 +508,8 @@ static const struct ptp_clock_info ptp_pch_caps = {
 	.enable		= ptp_pch_enable,
 };
 
-
-#ifdef CONFIG_PM
-static s32 pch_suspend(struct pci_dev *pdev, pm_message_t state)
-{
-	pci_disable_device(pdev);
-	pci_enable_wake(pdev, PCI_D3hot, 0);
-
-	if (pci_save_state(pdev) != 0) {
-		dev_err(&pdev->dev, "could not save PCI config state\n");
-		return -ENOMEM;
-	}
-	pci_set_power_state(pdev, pci_choose_state(pdev, state));
-
-	return 0;
-}
-
-static s32 pch_resume(struct pci_dev *pdev)
-{
-	s32 ret;
-
-	pci_set_power_state(pdev, PCI_D0);
-	pci_restore_state(pdev);
-	ret = pci_enable_device(pdev);
-	if (ret) {
-		dev_err(&pdev->dev, "pci_enable_device failed\n");
-		return ret;
-	}
-	pci_enable_wake(pdev, PCI_D3hot, 0);
-	return 0;
-}
-#else
 #define pch_suspend NULL
 #define pch_resume NULL
-#endif
 
 static void pch_remove(struct pci_dev *pdev)
 {
@@ -684,13 +652,14 @@ static const struct pci_device_id pch_ieee1588_pcidev_id[] = {
 	{0}
 };
 
+static SIMPLE_DEV_PM_OPS(pch_pm_ops, pch_suspend, pch_resume);
+
 static struct pci_driver pch_driver = {
 	.name = KBUILD_MODNAME,
 	.id_table = pch_ieee1588_pcidev_id,
 	.probe = pch_probe,
 	.remove = pch_remove,
-	.suspend = pch_suspend,
+	.driver.pm = &pch_pm_ops,
-	.resume = pch_resume,
 };
 
 static void __exit ptp_pch_exit(void)