Merge patch series "can: sja1000: Prepare the use of a threaded handler"

Miquel Raynal provides a series for the sja1000 driver to work around
overrun stalls with a soft reset on Renesas SoCs.

Link: https://lore.kernel.org/all/20230616134553.2786391-1-miquel.raynal@bootlin.comSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/sja1000/sja1000.c

@@ -387,6 +387,16 @@ static void sja1000_rx(struct net_device *dev)
 	netif_rx(skb);
 }
 
+static irqreturn_t sja1000_reset_interrupt(int irq, void *dev_id)
+{
+	struct net_device *dev = (struct net_device *)dev_id;
+
+	netdev_dbg(dev, "performing a soft reset upon overrun\n");
+	sja1000_start(dev);
+
+	return IRQ_HANDLED;
+}
+
 static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
 {
 	struct sja1000_priv *priv = netdev_priv(dev);
@@ -397,6 +407,7 @@ static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
 	enum can_state rx_state, tx_state;
 	unsigned int rxerr, txerr;
 	uint8_t ecc, alc;
+	int ret = 0;
 
 	skb = alloc_can_err_skb(dev, &cf);
 	if (skb == NULL)
@@ -413,6 +424,15 @@ static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
 		stats->rx_over_errors++;
 		stats->rx_errors++;
 		sja1000_write_cmdreg(priv, CMD_CDO);	/* clear bit */
+
+		/* Some controllers needs additional handling upon overrun
+		 * condition: the controller may sometimes be totally confused
+		 * and refuse any new frame while its buffer is empty. The only
+		 * way to re-sync the read vs. write buffer offsets is to
+		 * stop any current handling and perform a reset.
+		 */
+		if (priv->flags & SJA1000_QUIRK_RESET_ON_OVERRUN)
+			ret = IRQ_WAKE_THREAD;
 	}
 
 	if (isrc & IRQ_EI) {
@@ -492,7 +512,7 @@ static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
 
 	netif_rx(skb);
 
-	return 0;
+	return ret;
 }
 
 irqreturn_t sja1000_interrupt(int irq, void *dev_id)
@@ -501,7 +521,8 @@ irqreturn_t sja1000_interrupt(int irq, void *dev_id)
 	struct sja1000_priv *priv = netdev_priv(dev);
 	struct net_device_stats *stats = &dev->stats;
 	uint8_t isrc, status;
-	int n = 0;
+	irqreturn_t ret = 0;
+	int n = 0, err;
 
 	if (priv->pre_irq)
 		priv->pre_irq(priv);
@@ -546,19 +567,25 @@ irqreturn_t sja1000_interrupt(int irq, void *dev_id)
 		}
 		if (isrc & (IRQ_DOI | IRQ_EI | IRQ_BEI | IRQ_EPI | IRQ_ALI)) {
 			/* error interrupt */
-			if (sja1000_err(dev, isrc, status))
+			err = sja1000_err(dev, isrc, status);
+			if (err == IRQ_WAKE_THREAD)
+				ret = err;
+			if (err)
 				break;
 		}
 		n++;
 	}
 out:
+	if (!ret)
+		ret = (n) ? IRQ_HANDLED : IRQ_NONE;
+
 	if (priv->post_irq)
 		priv->post_irq(priv);
 
 	if (n >= SJA1000_MAX_IRQ)
 		netdev_dbg(dev, "%d messages handled in ISR", n);
 
-	return (n) ? IRQ_HANDLED : IRQ_NONE;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(sja1000_interrupt);
 
@@ -577,8 +604,9 @@ static int sja1000_open(struct net_device *dev)
 
 	/* register interrupt handler, if not done by the device driver */
 	if (!(priv->flags & SJA1000_CUSTOM_IRQ_HANDLER)) {
-		err = request_irq(dev->irq, sja1000_interrupt, priv->irq_flags,
-				  dev->name, (void *)dev);
+		err = request_threaded_irq(dev->irq, sja1000_interrupt,
+					   sja1000_reset_interrupt,
+					   priv->irq_flags, dev->name, (void *)dev);
 		if (err) {
 			close_candev(dev);
 			return -EAGAIN;

drivers/net/can/sja1000/sja1000.h

@@ -147,6 +147,7 @@
  */
 #define SJA1000_CUSTOM_IRQ_HANDLER	BIT(0)
 #define SJA1000_QUIRK_NO_CDR_REG	BIT(1)
+#define SJA1000_QUIRK_RESET_ON_OVERRUN	BIT(2)
 
 /*
  * SJA1000 private data structure

drivers/net/can/sja1000/sja1000_platform.c

@@ -106,7 +106,7 @@ static void sp_technologic_init(struct sja1000_priv *priv, struct device_node *o
 
 static void sp_rzn1_init(struct sja1000_priv *priv, struct device_node *of)
 {
-	priv->flags = SJA1000_QUIRK_NO_CDR_REG;
+	priv->flags = SJA1000_QUIRK_NO_CDR_REG | SJA1000_QUIRK_RESET_ON_OVERRUN;
 }
 
 static void sp_populate(struct sja1000_priv *priv,
@@ -277,6 +277,9 @@ static int sp_probe(struct platform_device *pdev)
 		priv->irq_flags = IRQF_SHARED;
 	}
 
+	if (priv->flags & SJA1000_QUIRK_RESET_ON_OVERRUN)
+		priv->irq_flags |= IRQF_ONESHOT;
+
 	dev->irq = irq;
 	priv->reg_base = addr;