dmaengine: pch_dma: use generic power management

Drivers using legacy PM have to manage PCI states and device's PM states
themselves. They also need to take care of configuration registers.

With improved and powerful support of generic PM, PCI Core takes care of
above mentioned, device-independent, jobs.

This driver makes use of PCI helper functions like
pci_save/restore_state(), pci_enable/disable_device(),
and pci_set_power_state() to do required operations. In generic mode, they
are no longer needed.

Change function parameter in both .suspend() and .resume() to
"struct device*" type. Use dev_get_drvdata() to get drv data.

Compile-tested only.
Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20200720113740.353479-1-vaibhavgupta40@gmail.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/pch_dma.c

@@ -735,8 +735,7 @@ static irqreturn_t pd_irq(int irq, void *devid)
 	return ret0 | ret2;
 }
 
-#ifdef	CONFIG_PM
-static void pch_dma_save_regs(struct pch_dma *pd)
+static void __maybe_unused pch_dma_save_regs(struct pch_dma *pd)
 {
 	struct pch_dma_chan *pd_chan;
 	struct dma_chan *chan, *_c;
@@ -759,7 +758,7 @@ static void pch_dma_save_regs(struct pch_dma *pd)
 	}
 }
 
-static void pch_dma_restore_regs(struct pch_dma *pd)
+static void __maybe_unused pch_dma_restore_regs(struct pch_dma *pd)
 {
 	struct pch_dma_chan *pd_chan;
 	struct dma_chan *chan, *_c;
@@ -782,40 +781,25 @@ static void pch_dma_restore_regs(struct pch_dma *pd)
 	}
 }
 
-static int pch_dma_suspend(struct pci_dev *pdev, pm_message_t state)
+static int __maybe_unused pch_dma_suspend(struct device *dev)
 {
-	struct pch_dma *pd = pci_get_drvdata(pdev);
+	struct pch_dma *pd = dev_get_drvdata(dev);
 
 	if (pd)
 		pch_dma_save_regs(pd);
 
-	pci_save_state(pdev);
-	pci_disable_device(pdev);
-	pci_set_power_state(pdev, pci_choose_state(pdev, state));
-
 	return 0;
 }
 
-static int pch_dma_resume(struct pci_dev *pdev)
+static int __maybe_unused pch_dma_resume(struct device *dev)
 {
-	struct pch_dma *pd = pci_get_drvdata(pdev);
-	int err;
-
-	pci_set_power_state(pdev, PCI_D0);
-	pci_restore_state(pdev);
-
-	err = pci_enable_device(pdev);
-	if (err) {
-		dev_dbg(&pdev->dev, "failed to enable device\n");
-		return err;
-	}
+	struct pch_dma *pd = dev_get_drvdata(dev);
 
 	if (pd)
 		pch_dma_restore_regs(pd);
 
 	return 0;
 }
-#endif
 
 static int pch_dma_probe(struct pci_dev *pdev,
 				   const struct pci_device_id *id)
@@ -993,15 +977,14 @@ static const struct pci_device_id pch_dma_id_table[] = {
 	{ 0, },
 };
 
+static SIMPLE_DEV_PM_OPS(pch_dma_pm_ops, pch_dma_suspend, pch_dma_resume);
+
 static struct pci_driver pch_dma_driver = {
 	.name		= DRV_NAME,
 	.id_table	= pch_dma_id_table,
 	.probe		= pch_dma_probe,
 	.remove		= pch_dma_remove,
-#ifdef CONFIG_PM
-	.suspend	= pch_dma_suspend,
-	.resume		= pch_dma_resume,
-#endif
+	.driver.pm	= &pch_dma_pm_ops,
 };
 
 module_pci_driver(pch_dma_driver);