can: m_can: Implement BQL

Implement byte queue limiting in preparation for the use of xmit_more().
Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Link: https://lore.kernel.org/all/20240207093220.2681425-14-msp@baylibre.comSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/m_can/m_can.c

@@ -489,6 +489,8 @@ static void m_can_clean(struct net_device *net)
 	for (int i = 0; i != cdev->can.echo_skb_max; ++i)
 		can_free_echo_skb(cdev->net, i, NULL);
 
+	netdev_reset_queue(cdev->net);
+
 	spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
 	cdev->tx_fifo_in_flight = 0;
 	spin_unlock_irqrestore(&cdev->tx_handling_spinlock, irqflags);
@@ -1043,29 +1045,34 @@ static int m_can_poll(struct napi_struct *napi, int quota)
  * echo. timestamp is used for peripherals to ensure correct ordering
  * by rx-offload, and is ignored for non-peripherals.
  */
-static void m_can_tx_update_stats(struct m_can_classdev *cdev,
-				  unsigned int msg_mark,
-				  u32 timestamp)
+static unsigned int m_can_tx_update_stats(struct m_can_classdev *cdev,
+					  unsigned int msg_mark, u32 timestamp)
 {
 	struct net_device *dev = cdev->net;
 	struct net_device_stats *stats = &dev->stats;
+	unsigned int frame_len;
 
 	if (cdev->is_peripheral)
 		stats->tx_bytes +=
 			can_rx_offload_get_echo_skb_queue_timestamp(&cdev->offload,
 								    msg_mark,
 								    timestamp,
-								    NULL);
+								    &frame_len);
 	else
-		stats->tx_bytes += can_get_echo_skb(dev, msg_mark, NULL);
+		stats->tx_bytes += can_get_echo_skb(dev, msg_mark, &frame_len);
 
 	stats->tx_packets++;
+
+	return frame_len;
 }
 
-static void m_can_finish_tx(struct m_can_classdev *cdev, int transmitted)
+static void m_can_finish_tx(struct m_can_classdev *cdev, int transmitted,
+			    unsigned int transmitted_frame_len)
 {
 	unsigned long irqflags;
 
+	netdev_completed_queue(cdev->net, transmitted, transmitted_frame_len);
+
 	spin_lock_irqsave(&cdev->tx_handling_spinlock, irqflags);
 	if (cdev->tx_fifo_in_flight >= cdev->tx_fifo_size && transmitted > 0)
 		netif_wake_queue(cdev->net);
@@ -1104,6 +1111,7 @@ static int m_can_echo_tx_event(struct net_device *dev)
 	int err = 0;
 	unsigned int msg_mark;
 	int processed = 0;
+	unsigned int processed_frame_len = 0;
 
 	struct m_can_classdev *cdev = netdev_priv(dev);
 
@@ -1132,7 +1140,9 @@ static int m_can_echo_tx_event(struct net_device *dev)
 		fgi = (++fgi >= cdev->mcfg[MRAM_TXE].num ? 0 : fgi);
 
 		/* update stats */
-		m_can_tx_update_stats(cdev, msg_mark, timestamp);
+		processed_frame_len += m_can_tx_update_stats(cdev, msg_mark,
+							     timestamp);
+
 		++processed;
 	}
 
@@ -1140,7 +1150,7 @@ static int m_can_echo_tx_event(struct net_device *dev)
 		m_can_write(cdev, M_CAN_TXEFA, FIELD_PREP(TXEFA_EFAI_MASK,
 							  ack_fgi));
 
-	m_can_finish_tx(cdev, processed);
+	m_can_finish_tx(cdev, processed, processed_frame_len);
 
 	return err;
 }
@@ -1218,11 +1228,12 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 		if (ir & IR_TC) {
 			/* Transmission Complete Interrupt*/
 			u32 timestamp = 0;
+			unsigned int frame_len;
 
 			if (cdev->is_peripheral)
 				timestamp = m_can_get_timestamp(cdev);
-			m_can_tx_update_stats(cdev, 0, timestamp);
-			m_can_finish_tx(cdev, 1);
+			frame_len = m_can_tx_update_stats(cdev, 0, timestamp);
+			m_can_finish_tx(cdev, 1, frame_len);
 		}
 	} else  {
 		if (ir & (IR_TEFN | IR_TEFW)) {
@@ -1738,6 +1749,7 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 	u32 cccr, fdflags;
 	int err;
 	u32 putidx;
+	unsigned int frame_len = can_skb_get_frame_len(skb);
 
 	/* Generate ID field for TX buffer Element */
 	/* Common to all supported M_CAN versions */
@@ -1783,7 +1795,7 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 		}
 		m_can_write(cdev, M_CAN_TXBTIE, 0x1);
 
-		can_put_echo_skb(skb, dev, 0, 0);
+		can_put_echo_skb(skb, dev, 0, frame_len);
 
 		m_can_write(cdev, M_CAN_TXBAR, 0x1);
 		/* End of xmit function for version 3.0.x */
@@ -1821,7 +1833,7 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev,
 		/* Push loopback echo.
 		 * Will be looped back on TX interrupt based on message marker
 		 */
-		can_put_echo_skb(skb, dev, putidx, 0);
+		can_put_echo_skb(skb, dev, putidx, frame_len);
 
 		/* Enable TX FIFO element to start transfer  */
 		m_can_write(cdev, M_CAN_TXBAR, (1 << putidx));
@@ -1869,11 +1881,14 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
 				    struct net_device *dev)
 {
 	struct m_can_classdev *cdev = netdev_priv(dev);
+	unsigned int frame_len;
 	netdev_tx_t ret;
 
 	if (can_dev_dropped_skb(dev, skb))
 		return NETDEV_TX_OK;
 
+	frame_len = can_skb_get_frame_len(skb);
+
 	if (cdev->can.state == CAN_STATE_BUS_OFF) {
 		m_can_clean(cdev->net);
 		return NETDEV_TX_OK;
@@ -1883,10 +1898,17 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
 	if (ret != NETDEV_TX_OK)
 		return ret;
 
+	netdev_sent_queue(dev, frame_len);
+
 	if (cdev->is_peripheral)
-		return m_can_start_peripheral_xmit(cdev, skb);
+		ret = m_can_start_peripheral_xmit(cdev, skb);
 	else
-		return m_can_tx_handler(cdev, skb);
+		ret = m_can_tx_handler(cdev, skb);
+
+	if (ret != NETDEV_TX_OK)
+		netdev_completed_queue(dev, 1, frame_len);
+
+	return ret;
 }
 
 static enum hrtimer_restart hrtimer_callback(struct hrtimer *timer)