net: macb: solve BSR after commit cb765f5

Commit cb765f5 "net: macb: do not disable MDIO bus at open/close
time" introduced the enable of management port only at probe and not
every time the interface was up. Doing so, the MPE bit of NCR must be
saved in suspend and restored in resume for BSR to work.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>

Author: claudiubeznea

drivers/net/ethernet/cadence/macb.h

@@ -1080,6 +1080,7 @@ struct macb_ptp_info {
 struct macb_sama5d2_pm_data {
 	u32 etht;
 	u32 usrio;
+	u32 ncr;
 };
 
 struct macb_pm_ops {

drivers/net/ethernet/cadence/macb_main.c

@@ -3919,6 +3919,8 @@ static int __maybe_unused macb_sama5d2_suspend(struct macb *bp)
 	if (!(bp->caps & MACB_CAPS_USRIO_DISABLED))
 		pm_data->usrio = macb_or_gem_readl(bp, USRIO);
 
+	pm_data->ncr = macb_readl(bp, NCR);
+
 	if (netif_running(netdev))
 		macb_close(netdev);
 
@@ -3933,6 +3935,8 @@ static int __maybe_unused macb_sama5d2_resume(struct macb *bp)
 	if (!macb_sama5d2_backup())
 		return -EPERM;
 
+	macb_writel(bp, NCR, pm_data->ncr & MACB_BIT(MPE));
+
 	if (netdev->hw_features & NETIF_F_NTUPLE)
 		gem_writel_n(bp, ETHT, SCRT2_ETHT, pm_data->etht);