net: fec: add pm runtime force suspend and resume support

Force mii bus into runtime pm suspend state during device suspends,
since phydev state is already PHY_HALTED, and there is no need to
access mii bus during device suspend state. Then force mii bus into
runtime pm resume state when device resumes.
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/fec.h

@@ -584,6 +584,7 @@ struct fec_enet_private {
 	struct device_node *phy_node;
 	bool	rgmii_txc_dly;
 	bool	rgmii_rxc_dly;
+	bool	rpm_active;
 	int	link;
 	int	full_duplex;
 	int	speed;

drivers/net/ethernet/freescale/fec_main.c

@@ -4135,6 +4135,7 @@ static int __maybe_unused fec_suspend(struct device *dev)
 {
 	struct net_device *ndev = dev_get_drvdata(dev);
 	struct fec_enet_private *fep = netdev_priv(ndev);
+	int ret;
 
 	rtnl_lock();
 	if (netif_running(ndev)) {
@@ -4159,6 +4160,15 @@ static int __maybe_unused fec_suspend(struct device *dev)
 		}
 		/* It's safe to disable clocks since interrupts are masked */
 		fec_enet_clk_enable(ndev, false);
+
+		fep->rpm_active = !pm_runtime_status_suspended(dev);
+		if (fep->rpm_active) {
+			ret = pm_runtime_force_suspend(dev);
+			if (ret < 0) {
+				rtnl_unlock();
+				return ret;
+			}
+		}
 	}
 	rtnl_unlock();
 
@@ -4189,6 +4199,9 @@ static int __maybe_unused fec_resume(struct device *dev)
 
 	rtnl_lock();
 	if (netif_running(ndev)) {
+		if (fep->rpm_active)
+			pm_runtime_force_resume(dev);
+
 		ret = fec_enet_clk_enable(ndev, true);
 		if (ret) {
 			rtnl_unlock();