net: ravb: Assert/de-assert reset on suspend/resume

RZ/G3S can go to deep sleep states where power to most of the SoC parts is
off. When resuming from such a state, the Ethernet controller needs to be
reinitialized. De-asserting the reset signal for it should also be done.
Thus, add reset assert/de-assert on suspend/resume functions.

On the resume function, the de-assert was not reverted in case of failures
to give the user a chance to restore the interface (e.g., bringing down/up
the interface) in case suspend/resume failed.
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/renesas/ravb_main.c

@@ -2978,7 +2978,7 @@ static int ravb_suspend(struct device *dev)
 	int ret;
 
 	if (!netif_running(ndev))
-		return 0;
+		goto reset_assert;
 
 	netif_device_detach(ndev);
 
@@ -2990,7 +2990,11 @@ static int ravb_suspend(struct device *dev)
 	if (priv->info->ccc_gac)
 		ravb_ptp_stop(ndev);
 
-	return ret;
+	if (priv->wol_enabled)
+		return ret;
+
+reset_assert:
+	return reset_control_assert(priv->rstc);
 }
 
 static int ravb_resume(struct device *dev)
@@ -2998,7 +3002,11 @@ static int ravb_resume(struct device *dev)
 	struct net_device *ndev = dev_get_drvdata(dev);
 	struct ravb_private *priv = netdev_priv(ndev);
 	const struct ravb_hw_info *info = priv->info;
-	int ret = 0;
+	int ret;
+
+	ret = reset_control_deassert(priv->rstc);
+	if (ret)
+		return ret;
 
 	/* If WoL is enabled set reset mode to rearm the WoL logic */
 	if (priv->wol_enabled) {