qede: fix firmware halt over suspend and resume

While performing certain power-off sequences, PCI drivers are
called to suspend and resume their underlying devices through
PCI PM (power management) interface. However this NIC hardware
does not support PCI PM suspend/resume operations so system wide
suspend/resume leads to bad MFW (management firmware) state which
causes various follow-up errors in driver when communicating with
the device/firmware afterwards.

To fix this driver implements PCI PM suspend handler to indicate
unsupported operation to the PCI subsystem explicitly, thus avoiding
system to go into suspended/standby mode.

Without this fix device/firmware does not recover unless system
is power cycled.

Fixes: 2950219 ("qede: Add basic network device support")
Signed-off-by: Manish Chopra <manishc@marvell.com>
Signed-off-by: Alok Prasad <palok@marvell.com>
Reviewed-by: John Meneghini <jmeneghi@redhat.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20230816150711.59035-1-manishc@marvell.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: manishc88

drivers/net/ethernet/qlogic/qede/qede_main.c

@@ -176,6 +176,15 @@ static int qede_sriov_configure(struct pci_dev *pdev, int num_vfs_param)
 }
 #endif
 
+static int __maybe_unused qede_suspend(struct device *dev)
+{
+	dev_info(dev, "Device does not support suspend operation\n");
+
+	return -EOPNOTSUPP;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(qede_pm_ops, qede_suspend, NULL);
+
 static const struct pci_error_handlers qede_err_handler = {
 	.error_detected = qede_io_error_detected,
 };
@@ -190,6 +199,7 @@ static struct pci_driver qede_pci_driver = {
 	.sriov_configure = qede_sriov_configure,
 #endif
 	.err_handler = &qede_err_handler,
+	.driver.pm = &qede_pm_ops,
 };
 
 static struct qed_eth_cb_ops qede_ll_ops = {