can: flexcan: flexcan_chip_stop(): add error handling and propagate error value

This patch implements error handling and propagates the error value of
flexcan_chip_stop(). This function will be called from flexcan_suspend()
in an upcoming patch in some SoCs which support LPSR mode.

Add a new function flexcan_chip_stop_disable_on_error() that tries to
disable the chip even in case of errors.
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
[mkl: introduce flexcan_chip_stop_disable_on_error() and use it in flexcan_close()]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20200922144429.2613631-11-mkl@pengutronix.de

drivers/net/can/flexcan.c

@@ -1292,18 +1292,23 @@ static int flexcan_chip_start(struct net_device *dev)
 	return err;
 }
 
-/* flexcan_chip_stop
+/* __flexcan_chip_stop
  *
- * this functions is entered with clocks enabled
+ * this function is entered with clocks enabled
  */
-static void flexcan_chip_stop(struct net_device *dev)
+static int __flexcan_chip_stop(struct net_device *dev, bool disable_on_error)
 {
 	struct flexcan_priv *priv = netdev_priv(dev);
 	struct flexcan_regs __iomem *regs = priv->regs;
+	int err;
 
 	/* freeze + disable module */
-	flexcan_chip_freeze(priv);
-	flexcan_chip_disable(priv);
+	err = flexcan_chip_freeze(priv);
+	if (err && !disable_on_error)
+		return err;
+	err = flexcan_chip_disable(priv);
+	if (err && !disable_on_error)
+		goto out_chip_unfreeze;
 
 	/* Disable all interrupts */
 	priv->write(0, &regs->imask2);
@@ -1313,6 +1318,23 @@ static void flexcan_chip_stop(struct net_device *dev)
 
 	flexcan_transceiver_disable(priv);
 	priv->can.state = CAN_STATE_STOPPED;
+
+	return 0;
+
+ out_chip_unfreeze:
+	flexcan_chip_unfreeze(priv);
+
+	return err;
+}
+
+static inline int flexcan_chip_stop_disable_on_error(struct net_device *dev)
+{
+	return __flexcan_chip_stop(dev, true);
+}
+
+static inline int flexcan_chip_stop(struct net_device *dev)
+{
+	return __flexcan_chip_stop(dev, false);
 }
 
 static int flexcan_open(struct net_device *dev)
@@ -1394,7 +1416,7 @@ static int flexcan_close(struct net_device *dev)
 
 	netif_stop_queue(dev);
 	can_rx_offload_disable(&priv->offload);
-	flexcan_chip_stop(dev);
+	flexcan_chip_stop_disable_on_error(dev);
 
 	can_rx_offload_del(&priv->offload);
 	free_irq(dev->irq, dev);