i2c: eg20t: use generic power management

Drivers using legacy power management .suspen()/.resume() callbacks
have to manage PCI states and device's PM states themselves. They also
need to take care of standard configuration registers.

Switch to generic power management framework using a single
"struct dev_pm_ops" variable to take the unnecessary load from the driver.
This also avoids the need for the driver to directly call most of the PCI
helper functions and device power state control functions, as through
the generic framework PCI Core takes care of the necessary operations,
and drivers are required to do only device-specific jobs.
Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-eg20t.c

@@ -846,11 +846,10 @@ static void pch_i2c_remove(struct pci_dev *pdev)
 	kfree(adap_info);
 }
 
-#ifdef CONFIG_PM
-static int pch_i2c_suspend(struct pci_dev *pdev, pm_message_t state)
+static int __maybe_unused pch_i2c_suspend(struct device *dev)
 {
-	int ret;
 	int i;
+	struct pci_dev *pdev = to_pci_dev(dev);
 	struct adapter_info *adap_info = pci_get_drvdata(pdev);
 	void __iomem *p = adap_info->pch_data[0].pch_base_address;
 
@@ -872,31 +871,13 @@ static int pch_i2c_suspend(struct pci_dev *pdev, pm_message_t state)
 		ioread32(p + PCH_I2CSR), ioread32(p + PCH_I2CBUFSTA),
 		ioread32(p + PCH_I2CESRSTA));
 
-	ret = pci_save_state(pdev);
-
-	if (ret) {
-		pch_pci_err(pdev, "pci_save_state\n");
-		return ret;
-	}
-
-	pci_disable_device(pdev);
-	pci_set_power_state(pdev, pci_choose_state(pdev, state));
-
 	return 0;
 }
 
-static int pch_i2c_resume(struct pci_dev *pdev)
+static int __maybe_unused pch_i2c_resume(struct device *dev)
 {
 	int i;
-	struct adapter_info *adap_info = pci_get_drvdata(pdev);
-
-	pci_set_power_state(pdev, PCI_D0);
-	pci_restore_state(pdev);
-
-	if (pci_enable_device(pdev) < 0) {
-		pch_pci_err(pdev, "pch_i2c_resume:pci_enable_device FAILED\n");
-		return -EIO;
-	}
+	struct adapter_info *adap_info = dev_get_drvdata(dev);
 
 	for (i = 0; i < adap_info->ch_num; i++)
 		pch_i2c_init(&adap_info->pch_data[i]);
@@ -905,18 +886,15 @@ static int pch_i2c_resume(struct pci_dev *pdev)
 
 	return 0;
 }
-#else
-#define pch_i2c_suspend NULL
-#define pch_i2c_resume NULL
-#endif
+
+static SIMPLE_DEV_PM_OPS(pch_i2c_pm_ops, pch_i2c_suspend, pch_i2c_resume);
 
 static struct pci_driver pch_pcidriver = {
 	.name = KBUILD_MODNAME,
 	.id_table = pch_pcidev_id,
 	.probe = pch_i2c_probe,
 	.remove = pch_i2c_remove,
-	.suspend = pch_i2c_suspend,
-	.resume = pch_i2c_resume
+	.driver.pm = &pch_i2c_pm_ops,
 };
 
 module_pci_driver(pch_pcidriver);