scsi: qedi: 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 the 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.

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.

Fixes: ace7f46ba5fd ("scsi: qedi: Add QLogic FastLinQ offload iSCSI driver framework.")
Signed-off-by: Nilesh Javali <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/qedi/qedi_main.c

···
 static void qedi_recovery_handler(struct work_struct *work);
 static void qedi_schedule_hw_err_handler(void *dev,
 					 enum qed_hw_err_type err_type);
+static int qedi_suspend(struct pci_dev *pdev, pm_message_t state);
 
 static int qedi_iscsi_event_cb(void *context, u8 fw_event_code, void *fw_handle)
 {
···
 	__qedi_remove(pdev, QEDI_MODE_SHUTDOWN);
 }
 
+static int qedi_suspend(struct pci_dev *pdev, pm_message_t state)
+{
+	struct qedi_ctx *qedi;
+
+	if (!pdev) {
+		QEDI_ERR(NULL, "pdev is NULL.\n");
+		return -ENODEV;
+	}
+
+	qedi = pci_get_drvdata(pdev);
+
+	QEDI_ERR(&qedi->dbg_ctx, "%s: Device does not support suspend operation\n", __func__);
+
+	return -EPERM;
+}
+
 static int __qedi_probe(struct pci_dev *pdev, int mode)
 {
 	struct qedi_ctx *qedi;
···
 	.remove = qedi_remove,
 	.shutdown = qedi_shutdown,
 	.err_handler = &qedi_err_handler,
+	.suspend = qedi_suspend,
 };
 
 static int __init qedi_init(void)