can: peak_usb: pcan_usb_decode_error(): upgrade handling of bus state changes

This patch updates old code by using the can_change_state() function
published since by the socket-can module.

In particular, this new code better manages the change of bus state by
also using the value of the error counters that the driver now
systematically asks for when initializing the channel.

Link: https://lore.kernel.org/r/20210715142842.35793-1-s.grosjean@peak-system.comSigned-off-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/usb/peak_usb/pcan_usb.c

@@ -452,145 +452,65 @@ static int pcan_usb_decode_error(struct pcan_usb_msg_context *mc, u8 n,
 {
 	struct sk_buff *skb;
 	struct can_frame *cf;
-	enum can_state new_state;
+	enum can_state new_state = CAN_STATE_ERROR_ACTIVE;
 
 	/* ignore this error until 1st ts received */
 	if (n == PCAN_USB_ERROR_QOVR)
 		if (!mc->pdev->time_ref.tick_count)
 			return 0;
 
-	new_state = mc->pdev->dev.can.state;
-
-	switch (mc->pdev->dev.can.state) {
-	case CAN_STATE_ERROR_ACTIVE:
-		if (n & PCAN_USB_ERROR_BUS_LIGHT) {
-			new_state = CAN_STATE_ERROR_WARNING;
-			break;
-		}
-		fallthrough;
+	/* allocate an skb to store the error frame */
+	skb = alloc_can_err_skb(mc->netdev, &cf);
 
-	case CAN_STATE_ERROR_WARNING:
-		if (n & PCAN_USB_ERROR_BUS_HEAVY) {
-			new_state = CAN_STATE_ERROR_PASSIVE;
-			break;
-		}
-		if (n & PCAN_USB_ERROR_BUS_OFF) {
-			new_state = CAN_STATE_BUS_OFF;
-			break;
-		}
-		if (n & ~PCAN_USB_ERROR_BUS) {
-			/*
-			 * trick to bypass next comparison and process other
-			 * errors
-			 */
-			new_state = CAN_STATE_MAX;
-			break;
+	if (n & PCAN_USB_ERROR_RXQOVR) {
+		/* data overrun interrupt */
+		netdev_dbg(mc->netdev, "data overrun interrupt\n");
+		mc->netdev->stats.rx_over_errors++;
+		mc->netdev->stats.rx_errors++;
+		if (cf) {
+			cf->can_id |= CAN_ERR_CRTL;
+			cf->data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;
 		}
-		if ((n & PCAN_USB_ERROR_BUS_LIGHT) == 0) {
-			/* no error (back to active state) */
-			new_state = CAN_STATE_ERROR_ACTIVE;
-			break;
 	}
-		break;
 
-	case CAN_STATE_ERROR_PASSIVE:
+	if (n & PCAN_USB_ERROR_TXQFULL)
+		netdev_dbg(mc->netdev, "device Tx queue full)\n");
+
 	if (n & PCAN_USB_ERROR_BUS_OFF) {
 		new_state = CAN_STATE_BUS_OFF;
-			break;
-		}
-		if (n & PCAN_USB_ERROR_BUS_LIGHT) {
-			new_state = CAN_STATE_ERROR_WARNING;
-			break;
-		}
-		if (n & ~PCAN_USB_ERROR_BUS) {
-			/*
-			 * trick to bypass next comparison and process other
-			 * errors
-			 */
-			new_state = CAN_STATE_MAX;
-			break;
-		}
-
-		if ((n & PCAN_USB_ERROR_BUS_HEAVY) == 0) {
-			/* no error (back to warning state) */
-			new_state = CAN_STATE_ERROR_WARNING;
-			break;
-		}
-		break;
-
-	default:
-		/* do nothing waiting for restart */
-		return 0;
+	} else if (n & PCAN_USB_ERROR_BUS_HEAVY) {
+		new_state = ((mc->pdev->bec.txerr >= 128) ||
+			     (mc->pdev->bec.rxerr >= 128)) ?
+				CAN_STATE_ERROR_PASSIVE :
+				CAN_STATE_ERROR_WARNING;
+	} else {
+		new_state = CAN_STATE_ERROR_ACTIVE;
 	}
 
-	/* donot post any error if current state didn't change */
-	if (mc->pdev->dev.can.state == new_state)
-		return 0;
+	/* handle change of state */
+	if (new_state != mc->pdev->dev.can.state) {
+		enum can_state tx_state =
+			(mc->pdev->bec.txerr >= mc->pdev->bec.rxerr) ?
+				new_state : 0;
+		enum can_state rx_state =
+			(mc->pdev->bec.txerr <= mc->pdev->bec.rxerr) ?
+				new_state : 0;
 
-	/* allocate an skb to store the error frame */
-	skb = alloc_can_err_skb(mc->netdev, &cf);
-	if (!skb)
-		return -ENOMEM;
+		can_change_state(mc->netdev, cf, tx_state, rx_state);
 
-	switch (new_state) {
-	case CAN_STATE_BUS_OFF:
-		cf->can_id |= CAN_ERR_BUSOFF;
-		mc->pdev->dev.can.can_stats.bus_off++;
+		if (new_state == CAN_STATE_BUS_OFF) {
 			can_bus_off(mc->netdev);
-		break;
-
-	case CAN_STATE_ERROR_PASSIVE:
-		cf->can_id |= CAN_ERR_CRTL;
-		cf->data[1] = (mc->pdev->bec.txerr > mc->pdev->bec.rxerr) ?
-				CAN_ERR_CRTL_TX_PASSIVE :
-				CAN_ERR_CRTL_RX_PASSIVE;
-		cf->data[6] = mc->pdev->bec.txerr;
-		cf->data[7] = mc->pdev->bec.rxerr;
-
-		mc->pdev->dev.can.can_stats.error_passive++;
-		break;
-
-	case CAN_STATE_ERROR_WARNING:
-		cf->can_id |= CAN_ERR_CRTL;
-		cf->data[1] = (mc->pdev->bec.txerr > mc->pdev->bec.rxerr) ?
-				CAN_ERR_CRTL_TX_WARNING :
-				CAN_ERR_CRTL_RX_WARNING;
+		} else if (cf && (cf->can_id & CAN_ERR_CRTL)) {
+			/* Supply TX/RX error counters in case of
+			 * controller error.
+			 */
 			cf->data[6] = mc->pdev->bec.txerr;
 			cf->data[7] = mc->pdev->bec.rxerr;
-
-		mc->pdev->dev.can.can_stats.error_warning++;
-		break;
-
-	case CAN_STATE_ERROR_ACTIVE:
-		cf->can_id |= CAN_ERR_CRTL;
-		cf->data[1] = CAN_ERR_CRTL_ACTIVE;
-
-		/* sync local copies of rxerr/txerr counters */
-		mc->pdev->bec.txerr = 0;
-		mc->pdev->bec.rxerr = 0;
-		break;
-
-	default:
-		/* CAN_STATE_MAX (trick to handle other errors) */
-		if (n & PCAN_USB_ERROR_TXQFULL)
-			netdev_dbg(mc->netdev, "device Tx queue full)\n");
-
-		if (n & PCAN_USB_ERROR_RXQOVR) {
-			netdev_dbg(mc->netdev, "data overrun interrupt\n");
-			cf->can_id |= CAN_ERR_CRTL;
-			cf->data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;
-			mc->netdev->stats.rx_over_errors++;
-			mc->netdev->stats.rx_errors++;
 		}
-
-		cf->data[6] = mc->pdev->bec.txerr;
-		cf->data[7] = mc->pdev->bec.rxerr;
-
-		new_state = mc->pdev->dev.can.state;
-		break;
 	}
 
-	mc->pdev->dev.can.state = new_state;
+	if (!skb)
+		return -ENOMEM;
 
 	if (status_len & PCAN_USB_STATUSLEN_TIMESTAMP) {
 		struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);