Merge patch series "can: gs_usb: convert to NAPI"

Marc Kleine-Budde <mkl@pengutronix.de> says:

Traditionally USB drivers used netif_rx to pass the received CAN
frames/skbs to the network stack. In netif_rx() the skbs are queued to
the local CPU. If IRQs are handled in round robin, CAN frames may be
delivered out-of-order to user space.

To support devices without timestamping the TX path of the rx-offload
helper is cleaned up and extended:
- rename rx_offload_get_echo_skb() ->
  can_rx_offload_get_echo_skb_queue_timestamp()
- add can_rx_offload_get_echo_skb_queue_tail()

The last patch converts the gs_usb driver to NAPI with the rx-offload
helper.

Link: https://lore.kernel.org/all/20230718-gs_usb-rx-offload-v2-0-716e542d14d5@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/dev/rx-offload.c

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /* Copyright (c) 2014      Protonic Holland,
  *                         David Jander
- * Copyright (C) 2014-2021 Pengutronix,
+ * Copyright (C) 2014-2021, 2023 Pengutronix,
  *                         Marc Kleine-Budde <kernel@pengutronix.de>
  */
 
@@ -240,9 +240,10 @@ int can_rx_offload_queue_timestamp(struct can_rx_offload *offload,
 }
 EXPORT_SYMBOL_GPL(can_rx_offload_queue_timestamp);
 
-unsigned int can_rx_offload_get_echo_skb(struct can_rx_offload *offload,
-					 unsigned int idx, u32 timestamp,
-					 unsigned int *frame_len_ptr)
+unsigned int
+can_rx_offload_get_echo_skb_queue_timestamp(struct can_rx_offload *offload,
+					    unsigned int idx, u32 timestamp,
+					    unsigned int *frame_len_ptr)
 {
 	struct net_device *dev = offload->dev;
 	struct net_device_stats *stats = &dev->stats;
@@ -262,7 +263,7 @@ unsigned int can_rx_offload_get_echo_skb(struct can_rx_offload *offload,
 
 	return len;
 }
-EXPORT_SYMBOL_GPL(can_rx_offload_get_echo_skb);
+EXPORT_SYMBOL_GPL(can_rx_offload_get_echo_skb_queue_timestamp);
 
 int can_rx_offload_queue_tail(struct can_rx_offload *offload,
 			      struct sk_buff *skb)
@@ -279,6 +280,31 @@ int can_rx_offload_queue_tail(struct can_rx_offload *offload,
 }
 EXPORT_SYMBOL_GPL(can_rx_offload_queue_tail);
 
+unsigned int
+can_rx_offload_get_echo_skb_queue_tail(struct can_rx_offload *offload,
+				       unsigned int idx,
+				       unsigned int *frame_len_ptr)
+{
+	struct net_device *dev = offload->dev;
+	struct net_device_stats *stats = &dev->stats;
+	struct sk_buff *skb;
+	unsigned int len;
+	int err;
+
+	skb = __can_get_echo_skb(dev, idx, &len, frame_len_ptr);
+	if (!skb)
+		return 0;
+
+	err = can_rx_offload_queue_tail(offload, skb);
+	if (err) {
+		stats->rx_errors++;
+		stats->tx_fifo_errors++;
+	}
+
+	return len;
+}
+EXPORT_SYMBOL_GPL(can_rx_offload_get_echo_skb_queue_tail);
+
 void can_rx_offload_irq_finish(struct can_rx_offload *offload)
 {
 	unsigned long flags;

drivers/net/can/flexcan/flexcan-core.c

@@ -1097,8 +1097,8 @@ static irqreturn_t flexcan_irq(int irq, void *dev_id)
 
 		handled = IRQ_HANDLED;
 		stats->tx_bytes +=
-			can_rx_offload_get_echo_skb(&priv->offload, 0,
-						    reg_ctrl << 16, NULL);
+			can_rx_offload_get_echo_skb_queue_timestamp(&priv->offload, 0,
+								    reg_ctrl << 16, NULL);
 		stats->tx_packets++;
 
 		/* after sending a RTR frame MB is in RX mode */

drivers/net/can/m_can/m_can.c

@@ -1016,10 +1016,10 @@ static void m_can_tx_update_stats(struct m_can_classdev *cdev,
 
 	if (cdev->is_peripheral)
 		stats->tx_bytes +=
-			can_rx_offload_get_echo_skb(&cdev->offload,
-						    msg_mark,
-						    timestamp,
-						    NULL);
+			can_rx_offload_get_echo_skb_queue_timestamp(&cdev->offload,
+								    msg_mark,
+								    timestamp,
+								    NULL);
 	else
 		stats->tx_bytes += can_get_echo_skb(dev, msg_mark, NULL);
 

drivers/net/can/spi/mcp251xfd/mcp251xfd-tef.c

@@ -111,9 +111,9 @@ mcp251xfd_handle_tefif_one(struct mcp251xfd_priv *priv,
 	if (skb)
 		mcp251xfd_skb_set_timestamp(priv, skb, hw_tef_obj->ts);
 	stats->tx_bytes +=
-		can_rx_offload_get_echo_skb(&priv->offload,
-					    tef_tail, hw_tef_obj->ts,
-					    frame_len_ptr);
+		can_rx_offload_get_echo_skb_queue_timestamp(&priv->offload,
+							    tef_tail, hw_tef_obj->ts,
+							    frame_len_ptr);
 	stats->tx_packets++;
 	priv->tef->tail++;
 

drivers/net/can/ti_hecc.c

@@ -747,8 +747,8 @@ static irqreturn_t ti_hecc_interrupt(int irq, void *dev_id)
 			spin_unlock_irqrestore(&priv->mbx_lock, flags);
 			stamp = hecc_read_stamp(priv, mbxno);
 			stats->tx_bytes +=
-				can_rx_offload_get_echo_skb(&priv->offload,
-							    mbxno, stamp, NULL);
+				can_rx_offload_get_echo_skb_queue_timestamp(&priv->offload,
+									    mbxno, stamp, NULL);
 			stats->tx_packets++;
 			--priv->tx_tail;
 		}

drivers/net/can/usb/Kconfig

@@ -52,6 +52,7 @@ config CAN_F81604
 
 config CAN_GS_USB
 	tristate "Geschwister Schneider UG and candleLight compatible interfaces"
+	select CAN_RX_OFFLOAD
 	help
 	  This driver supports the Geschwister Schneider and
 	  bytewerk.org candleLight compatible

drivers/net/can/usb/gs_usb.c

@@ -5,6 +5,7 @@
  * Copyright (C) 2013-2016 Geschwister Schneider Technologie-,
  * Entwicklungs- und Vertriebs UG (Haftungsbeschränkt).
  * Copyright (C) 2016 Hubert Denkmair
+ * Copyright (c) 2023 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
  *
  * Many thanks to all socketcan devs!
  */
@@ -24,6 +25,7 @@
 #include <linux/can.h>
 #include <linux/can/dev.h>
 #include <linux/can/error.h>
+#include <linux/can/rx-offload.h>
 
 /* Device specific constants */
 #define USB_GS_USB_1_VENDOR_ID 0x1d50
@@ -282,6 +284,8 @@ struct gs_host_frame {
 #define GS_MAX_TX_URBS 10
 /* Only launch a max of GS_MAX_RX_URBS usb requests at a time. */
 #define GS_MAX_RX_URBS 30
+#define GS_NAPI_WEIGHT 32
+
 /* Maximum number of interfaces the driver supports per device.
  * Current hardware only supports 3 interfaces. The future may vary.
  */
@@ -295,6 +299,7 @@ struct gs_tx_context {
 struct gs_can {
 	struct can_priv can; /* must be the first member */
 
+	struct can_rx_offload offload;
 	struct gs_usb *parent;
 
 	struct net_device *netdev;
@@ -506,20 +511,59 @@ static void gs_update_state(struct gs_can *dev, struct can_frame *cf)
 	}
 }
 
-static void gs_usb_set_timestamp(struct gs_can *dev, struct sk_buff *skb,
-				 const struct gs_host_frame *hf)
+static u32 gs_usb_set_timestamp(struct gs_can *dev, struct sk_buff *skb,
+				const struct gs_host_frame *hf)
 {
 	u32 timestamp;
 
-	if (!(dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP))
-		return;
-
 	if (hf->flags & GS_CAN_FLAG_FD)
 		timestamp = le32_to_cpu(hf->canfd_ts->timestamp_us);
 	else
 		timestamp = le32_to_cpu(hf->classic_can_ts->timestamp_us);
 
-	gs_usb_skb_set_timestamp(dev, skb, timestamp);
+	if (skb)
+		gs_usb_skb_set_timestamp(dev, skb, timestamp);
+
+	return timestamp;
+}
+
+static void gs_usb_rx_offload(struct gs_can *dev, struct sk_buff *skb,
+			      const struct gs_host_frame *hf)
+{
+	struct can_rx_offload *offload = &dev->offload;
+	int rc;
+
+	if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP) {
+		const u32 ts = gs_usb_set_timestamp(dev, skb, hf);
+
+		rc = can_rx_offload_queue_timestamp(offload, skb, ts);
+	} else {
+		rc = can_rx_offload_queue_tail(offload, skb);
+	}
+
+	if (rc)
+		dev->netdev->stats.rx_fifo_errors++;
+}
+
+static unsigned int
+gs_usb_get_echo_skb(struct gs_can *dev, struct sk_buff *skb,
+		    const struct gs_host_frame *hf)
+{
+	struct can_rx_offload *offload = &dev->offload;
+	const u32 echo_id = hf->echo_id;
+	unsigned int len;
+
+	if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP) {
+		const u32 ts = gs_usb_set_timestamp(dev, skb, hf);
+
+		len = can_rx_offload_get_echo_skb_queue_timestamp(offload, echo_id,
+								  ts, NULL);
+	} else {
+		len = can_rx_offload_get_echo_skb_queue_tail(offload, echo_id,
+							     NULL);
+	}
+
+	return len;
 }
 
 static void gs_usb_receive_bulk_callback(struct urb *urb)
@@ -592,12 +636,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 				gs_update_state(dev, cf);
 		}
 
-		gs_usb_set_timestamp(dev, skb, hf);
-
-		stats->rx_packets++;
-		stats->rx_bytes += hf->can_dlc;
-
-		netif_rx(skb);
+		gs_usb_rx_offload(dev, skb, hf);
 	} else { /* echo_id == hf->echo_id */
 		if (hf->echo_id >= GS_MAX_TX_URBS) {
 			netdev_err(netdev,
@@ -617,12 +656,8 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 		}
 
 		skb = dev->can.echo_skb[hf->echo_id];
-		gs_usb_set_timestamp(dev, skb, hf);
-
 		stats->tx_packets++;
-		stats->tx_bytes += can_get_echo_skb(netdev, hf->echo_id,
-						    NULL);
-
+		stats->tx_bytes += gs_usb_get_echo_skb(dev, skb, hf);
 		gs_free_tx_context(txc);
 
 		atomic_dec(&dev->active_tx_urbs);
@@ -641,9 +676,12 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 		cf->can_id |= CAN_ERR_CRTL;
 		cf->len = CAN_ERR_DLC;
 		cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
-		netif_rx(skb);
+
+		gs_usb_rx_offload(dev, skb, hf);
 	}
 
+	can_rx_offload_irq_finish(&dev->offload);
+
 resubmit_urb:
 	usb_fill_bulk_urb(urb, parent->udev,
 			  usb_rcvbulkpipe(parent->udev, GS_USB_ENDPOINT_IN),
@@ -857,6 +895,8 @@ static int gs_can_open(struct net_device *netdev)
 			dev->hf_size_tx = struct_size(hf, classic_can, 1);
 	}
 
+	can_rx_offload_enable(&dev->offload);
+
 	if (!parent->active_channels) {
 		if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
 			gs_usb_timestamp_init(parent);
@@ -965,6 +1005,7 @@ static int gs_can_open(struct net_device *netdev)
 			gs_usb_timestamp_stop(parent);
 	}
 
+	can_rx_offload_disable(&dev->offload);
 	close_candev(netdev);
 
 	return rc;
@@ -1037,6 +1078,8 @@ static int gs_can_close(struct net_device *netdev)
 		dev->tx_context[rc].echo_id = GS_MAX_TX_URBS;
 	}
 
+	can_rx_offload_disable(&dev->offload);
+
 	/* close the netdev */
 	close_candev(netdev);
 
@@ -1336,18 +1379,21 @@ static struct gs_can *gs_make_candev(unsigned int channel,
 		dev->can.data_bittiming_const = &dev->data_bt_const;
 	}
 
+	can_rx_offload_add_manual(netdev, &dev->offload, GS_NAPI_WEIGHT);
 	SET_NETDEV_DEV(netdev, &intf->dev);
 
 	rc = register_candev(dev->netdev);
 	if (rc) {
 		dev_err(&intf->dev,
 			"Couldn't register candev for channel %d (%pe)\n",
 			channel, ERR_PTR(rc));
-		goto out_free_candev;
+		goto out_can_rx_offload_del;
 	}
 
 	return dev;
 
+out_can_rx_offload_del:
+	can_rx_offload_del(&dev->offload);
 out_free_candev:
 	free_candev(dev->netdev);
 	return ERR_PTR(rc);
@@ -1356,6 +1402,7 @@ static struct gs_can *gs_make_candev(unsigned int channel,
 static void gs_destroy_candev(struct gs_can *dev)
 {
 	unregister_candev(dev->netdev);
+	can_rx_offload_del(&dev->offload);
 	free_candev(dev->netdev);
 }
 

include/linux/can/rx-offload.h

@@ -3,7 +3,7 @@
  * linux/can/rx-offload.h
  *
  * Copyright (c) 2014 David Jander, Protonic Holland
- * Copyright (c) 2014-2017 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
+ * Copyright (c) 2014-2017, 2023 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
  */
 
 #ifndef _CAN_RX_OFFLOAD_H
@@ -44,11 +44,14 @@ int can_rx_offload_irq_offload_timestamp(struct can_rx_offload *offload,
 int can_rx_offload_irq_offload_fifo(struct can_rx_offload *offload);
 int can_rx_offload_queue_timestamp(struct can_rx_offload *offload,
 				   struct sk_buff *skb, u32 timestamp);
-unsigned int can_rx_offload_get_echo_skb(struct can_rx_offload *offload,
-					 unsigned int idx, u32 timestamp,
-					 unsigned int *frame_len_ptr);
+unsigned int can_rx_offload_get_echo_skb_queue_timestamp(struct can_rx_offload *offload,
+							 unsigned int idx, u32 timestamp,
+							 unsigned int *frame_len_ptr);
 int can_rx_offload_queue_tail(struct can_rx_offload *offload,
 			      struct sk_buff *skb);
+unsigned int can_rx_offload_get_echo_skb_queue_tail(struct can_rx_offload *offload,
+						    unsigned int idx,
+						    unsigned int *frame_len_ptr);
 void can_rx_offload_irq_finish(struct can_rx_offload *offload);
 void can_rx_offload_threaded_irq_finish(struct can_rx_offload *offload);
 void can_rx_offload_del(struct can_rx_offload *offload);