Merge tag 'linux-can-next-for-5.12-20210114' of...

Merge tag 'linux-can-next-for-5.12-20210114' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next

Marc Kleine-Budde says:

====================
pull-request: can-next 2021-01-14

The first two patches update the MAINTAINERS file, Lukas Bulwahn's patch fixes
the files entry for the tcan4x5x driver, which was broken by me in net-next.
A patch by me adds the a missing header file to the CAN Networking Layer.

The next 5 patches are by me and split the the CAN driver related
infrastructure code into more files in a separate subdir. The next two patches
by me clean up the CAN length related code. This is followed by 6 patches by
Vincent Mailhol and me, they add helper code for for CAN frame length
calculation neede for BQL support.

A patch by Vincent Mailhol adds software TX timestamp support.

The last patch is by me, targets the tcan4x5x driver, and removes the unneeded
__packed attribute from the struct tcan4x5x_map_buf.

* tag 'linux-can-next-for-5.12-20210114' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next:
  can: tcan4x5x: remove __packed attribute from struct tcan4x5x_map_buf
  can: dev: can_put_echo_skb(): add software tx timestamps
  can: dev: can_rx_offload_get_echo_skb(): extend to return can frame length
  can: dev: can_get_echo_skb(): extend to return can frame length
  can: dev: can_put_echo_skb(): extend to handle frame_len
  can: dev: extend struct can_skb_priv to hold CAN frame length
  can: length: can_skb_get_frame_len(): introduce function to get data length of frame in data link layer
  can: length: canfd_sanitize_len(): add function to sanitize CAN-FD data length
  can: length: can_fd_len2dlc(): simplify length calculcation
  can: length: convert to kernel coding style
  can: dev: move netlink related code into seperate file
  can: dev: move skb related into seperate file
  can: dev: move length related code into seperate file
  can: dev: move bittiming related code into seperate file
  can: dev: move driver related infrastructure into separate subdir
  MAINTAINERS: CAN network layer: add missing header file can-ml.h
  MAINTAINERS: adjust entry to tcan4x5x file split
====================

Link: https://lore.kernel.org/r/20210114075617.1402597-1-mkl@pengutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

MAINTAINERS

@@ -3943,8 +3943,10 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can.git
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next.git
 F:	Documentation/devicetree/bindings/net/can/
 F:	drivers/net/can/
+F:	include/linux/can/bittiming.h
 F:	include/linux/can/dev.h
 F:	include/linux/can/led.h
+F:	include/linux/can/length.h
 F:	include/linux/can/platform/
 F:	include/linux/can/rx-offload.h
 F:	include/uapi/linux/can/error.h
@@ -3960,6 +3962,7 @@ W:	https://github.com/linux-can
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can.git
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next.git
 F:	Documentation/networking/can.rst
+F:	include/linux/can/can-ml.h
 F:	include/linux/can/core.h
 F:	include/linux/can/skb.h
 F:	include/net/netns/can.h
@@ -17839,7 +17842,7 @@ M:	Dan Murphy <dmurphy@ti.com>
 L:	linux-can@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/net/can/tcan4x5x.txt
-F:	drivers/net/can/m_can/tcan4x5x.c
+F:	drivers/net/can/m_can/tcan4x5x*
 
 TI TRF7970A NFC DRIVER
 M:	Mark Greer <mgreer@animalcreek.com>

drivers/net/can/Makefile

@@ -7,12 +7,7 @@ obj-$(CONFIG_CAN_VCAN)		+= vcan.o
 obj-$(CONFIG_CAN_VXCAN)		+= vxcan.o
 obj-$(CONFIG_CAN_SLCAN)		+= slcan.o
 
-obj-$(CONFIG_CAN_DEV)		+= can-dev.o
-can-dev-y			+= dev.o
-can-dev-y			+= rx-offload.o
-
-can-dev-$(CONFIG_CAN_LEDS)	+= led.o
-
+obj-y				+= dev/
 obj-y				+= rcar/
 obj-y				+= spi/
 obj-y				+= usb/

drivers/net/can/at91_can.c

@@ -484,7 +484,7 @@ static netdev_tx_t at91_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	stats->tx_bytes += cf->len;
 
 	/* _NOTE_: subtract AT91_MB_TX_FIRST offset from mb! */
-	can_put_echo_skb(skb, dev, mb - get_mb_tx_first(priv));
+	can_put_echo_skb(skb, dev, mb - get_mb_tx_first(priv), 0);
 
 	/*
 	 * we have to stop the queue and deliver all messages in case
@@ -856,7 +856,7 @@ static void at91_irq_tx(struct net_device *dev, u32 reg_sr)
 		if (likely(reg_msr & AT91_MSR_MRDY &&
 			   ~reg_msr & AT91_MSR_MABT)) {
 			/* _NOTE_: subtract AT91_MB_TX_FIRST offset from mb! */
-			can_get_echo_skb(dev, mb - get_mb_tx_first(priv));
+			can_get_echo_skb(dev, mb - get_mb_tx_first(priv), NULL);
 			dev->stats.tx_packets++;
 			can_led_event(dev, CAN_LED_EVENT_TX);
 		}

drivers/net/can/c_can/c_can.c

@@ -476,7 +476,7 @@ static netdev_tx_t c_can_start_xmit(struct sk_buff *skb,
 	 */
 	c_can_setup_tx_object(dev, IF_TX, frame, idx);
 	priv->dlc[idx] = frame->len;
-	can_put_echo_skb(skb, dev, idx);
+	can_put_echo_skb(skb, dev, idx, 0);
 
 	/* Update the active bits */
 	atomic_add((1 << idx), &priv->tx_active);
@@ -733,7 +733,7 @@ static void c_can_do_tx(struct net_device *dev)
 		pend &= ~(1 << idx);
 		obj = idx + C_CAN_MSG_OBJ_TX_FIRST;
 		c_can_inval_tx_object(dev, IF_RX, obj);
-		can_get_echo_skb(dev, idx);
+		can_get_echo_skb(dev, idx, NULL);
 		bytes += priv->dlc[idx];
 		pkts++;
 	}

drivers/net/can/cc770/cc770.c

@@ -702,8 +702,8 @@ static void cc770_tx_interrupt(struct net_device *dev, unsigned int o)
 	stats->tx_bytes += cf->len;
 	stats->tx_packets++;
 
-	can_put_echo_skb(priv->tx_skb, dev, 0);
-	can_get_echo_skb(dev, 0);
+	can_put_echo_skb(priv->tx_skb, dev, 0, 0);
+	can_get_echo_skb(dev, 0, NULL);
 	priv->tx_skb = NULL;
 
 	netif_wake_queue(dev);

drivers/net/can/dev/Makefile

+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_CAN_DEV)		+= can-dev.o
+can-dev-y			+= bittiming.o
+can-dev-y			+= dev.o
+can-dev-y			+= length.o
+can-dev-y			+= netlink.o
+can-dev-y			+= rx-offload.o
+can-dev-y                       += skb.o
+
+can-dev-$(CONFIG_CAN_LEDS)	+= led.o

drivers/net/can/dev/bittiming.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
+ * Copyright (C) 2006 Andrey Volkov, Varma Electronics
+ * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
+ */
+
+#include <linux/can/dev.h>
+
+#ifdef CONFIG_CAN_CALC_BITTIMING
+#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
+
+/* Bit-timing calculation derived from:
+ *
+ * Code based on LinCAN sources and H8S2638 project
+ * Copyright 2004-2006 Pavel Pisa - DCE FELK CVUT cz
+ * Copyright 2005      Stanislav Marek
+ * email: pisa@cmp.felk.cvut.cz
+ *
+ * Calculates proper bit-timing parameters for a specified bit-rate
+ * and sample-point, which can then be used to set the bit-timing
+ * registers of the CAN controller. You can find more information
+ * in the header file linux/can/netlink.h.
+ */
+static int
+can_update_sample_point(const struct can_bittiming_const *btc,
+			unsigned int sample_point_nominal, unsigned int tseg,
+			unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,
+			unsigned int *sample_point_error_ptr)
+{
+	unsigned int sample_point_error, best_sample_point_error = UINT_MAX;
+	unsigned int sample_point, best_sample_point = 0;
+	unsigned int tseg1, tseg2;
+	int i;
+
+	for (i = 0; i <= 1; i++) {
+		tseg2 = tseg + CAN_SYNC_SEG -
+			(sample_point_nominal * (tseg + CAN_SYNC_SEG)) /
+			1000 - i;
+		tseg2 = clamp(tseg2, btc->tseg2_min, btc->tseg2_max);
+		tseg1 = tseg - tseg2;
+		if (tseg1 > btc->tseg1_max) {
+			tseg1 = btc->tseg1_max;
+			tseg2 = tseg - tseg1;
+		}
+
+		sample_point = 1000 * (tseg + CAN_SYNC_SEG - tseg2) /
+			(tseg + CAN_SYNC_SEG);
+		sample_point_error = abs(sample_point_nominal - sample_point);
+
+		if (sample_point <= sample_point_nominal &&
+		    sample_point_error < best_sample_point_error) {
+			best_sample_point = sample_point;
+			best_sample_point_error = sample_point_error;
+			*tseg1_ptr = tseg1;
+			*tseg2_ptr = tseg2;
+		}
+	}
+
+	if (sample_point_error_ptr)
+		*sample_point_error_ptr = best_sample_point_error;
+
+	return best_sample_point;
+}
+
+int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
+		       const struct can_bittiming_const *btc)
+{
+	struct can_priv *priv = netdev_priv(dev);
+	unsigned int bitrate;			/* current bitrate */
+	unsigned int bitrate_error;		/* difference between current and nominal value */
+	unsigned int best_bitrate_error = UINT_MAX;
+	unsigned int sample_point_error;	/* difference between current and nominal value */
+	unsigned int best_sample_point_error = UINT_MAX;
+	unsigned int sample_point_nominal;	/* nominal sample point */
+	unsigned int best_tseg = 0;		/* current best value for tseg */
+	unsigned int best_brp = 0;		/* current best value for brp */
+	unsigned int brp, tsegall, tseg, tseg1 = 0, tseg2 = 0;
+	u64 v64;
+
+	/* Use CiA recommended sample points */
+	if (bt->sample_point) {
+		sample_point_nominal = bt->sample_point;
+	} else {
+		if (bt->bitrate > 800000)
+			sample_point_nominal = 750;
+		else if (bt->bitrate > 500000)
+			sample_point_nominal = 800;
+		else
+			sample_point_nominal = 875;
+	}
+
+	/* tseg even = round down, odd = round up */
+	for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1;
+	     tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {
+		tsegall = CAN_SYNC_SEG + tseg / 2;
+
+		/* Compute all possible tseg choices (tseg=tseg1+tseg2) */
+		brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;
+
+		/* choose brp step which is possible in system */
+		brp = (brp / btc->brp_inc) * btc->brp_inc;
+		if (brp < btc->brp_min || brp > btc->brp_max)
+			continue;
+
+		bitrate = priv->clock.freq / (brp * tsegall);
+		bitrate_error = abs(bt->bitrate - bitrate);
+
+		/* tseg brp biterror */
+		if (bitrate_error > best_bitrate_error)
+			continue;
+
+		/* reset sample point error if we have a better bitrate */
+		if (bitrate_error < best_bitrate_error)
+			best_sample_point_error = UINT_MAX;
+
+		can_update_sample_point(btc, sample_point_nominal, tseg / 2,
+					&tseg1, &tseg2, &sample_point_error);
+		if (sample_point_error > best_sample_point_error)
+			continue;
+
+		best_sample_point_error = sample_point_error;
+		best_bitrate_error = bitrate_error;
+		best_tseg = tseg / 2;
+		best_brp = brp;
+
+		if (bitrate_error == 0 && sample_point_error == 0)
+			break;
+	}
+
+	if (best_bitrate_error) {
+		/* Error in one-tenth of a percent */
+		v64 = (u64)best_bitrate_error * 1000;
+		do_div(v64, bt->bitrate);
+		bitrate_error = (u32)v64;
+		if (bitrate_error > CAN_CALC_MAX_ERROR) {
+			netdev_err(dev,
+				   "bitrate error %d.%d%% too high\n",
+				   bitrate_error / 10, bitrate_error % 10);
+			return -EDOM;
+		}
+		netdev_warn(dev, "bitrate error %d.%d%%\n",
+			    bitrate_error / 10, bitrate_error % 10);
+	}
+
+	/* real sample point */
+	bt->sample_point = can_update_sample_point(btc, sample_point_nominal,
+						   best_tseg, &tseg1, &tseg2,
+						   NULL);
+
+	v64 = (u64)best_brp * 1000 * 1000 * 1000;
+	do_div(v64, priv->clock.freq);
+	bt->tq = (u32)v64;
+	bt->prop_seg = tseg1 / 2;
+	bt->phase_seg1 = tseg1 - bt->prop_seg;
+	bt->phase_seg2 = tseg2;
+
+	/* check for sjw user settings */
+	if (!bt->sjw || !btc->sjw_max) {
+		bt->sjw = 1;
+	} else {
+		/* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */
+		if (bt->sjw > btc->sjw_max)
+			bt->sjw = btc->sjw_max;
+		/* bt->sjw must not be higher than tseg2 */
+		if (tseg2 < bt->sjw)
+			bt->sjw = tseg2;
+	}
+
+	bt->brp = best_brp;
+
+	/* real bitrate */
+	bt->bitrate = priv->clock.freq /
+		(bt->brp * (CAN_SYNC_SEG + tseg1 + tseg2));
+
+	return 0;
+}
+#endif /* CONFIG_CAN_CALC_BITTIMING */
+
+/* Checks the validity of the specified bit-timing parameters prop_seg,
+ * phase_seg1, phase_seg2 and sjw and tries to determine the bitrate
+ * prescaler value brp. You can find more information in the header
+ * file linux/can/netlink.h.
+ */
+static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt,
+			       const struct can_bittiming_const *btc)
+{
+	struct can_priv *priv = netdev_priv(dev);
+	int tseg1, alltseg;
+	u64 brp64;
+
+	tseg1 = bt->prop_seg + bt->phase_seg1;
+	if (!bt->sjw)
+		bt->sjw = 1;
+	if (bt->sjw > btc->sjw_max ||
+	    tseg1 < btc->tseg1_min || tseg1 > btc->tseg1_max ||
+	    bt->phase_seg2 < btc->tseg2_min || bt->phase_seg2 > btc->tseg2_max)
+		return -ERANGE;
+
+	brp64 = (u64)priv->clock.freq * (u64)bt->tq;
+	if (btc->brp_inc > 1)
+		do_div(brp64, btc->brp_inc);
+	brp64 += 500000000UL - 1;
+	do_div(brp64, 1000000000UL); /* the practicable BRP */
+	if (btc->brp_inc > 1)
+		brp64 *= btc->brp_inc;
+	bt->brp = (u32)brp64;
+
+	if (bt->brp < btc->brp_min || bt->brp > btc->brp_max)
+		return -EINVAL;
+
+	alltseg = bt->prop_seg + bt->phase_seg1 + bt->phase_seg2 + 1;
+	bt->bitrate = priv->clock.freq / (bt->brp * alltseg);
+	bt->sample_point = ((tseg1 + 1) * 1000) / alltseg;
+
+	return 0;
+}
+
+/* Checks the validity of predefined bitrate settings */
+static int
+can_validate_bitrate(struct net_device *dev, struct can_bittiming *bt,
+		     const u32 *bitrate_const,
+		     const unsigned int bitrate_const_cnt)
+{
+	struct can_priv *priv = netdev_priv(dev);
+	unsigned int i;
+
+	for (i = 0; i < bitrate_const_cnt; i++) {
+		if (bt->bitrate == bitrate_const[i])
+			break;
+	}
+
+	if (i >= priv->bitrate_const_cnt)
+		return -EINVAL;
+
+	return 0;
+}
+
+int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,
+		      const struct can_bittiming_const *btc,
+		      const u32 *bitrate_const,
+		      const unsigned int bitrate_const_cnt)
+{
+	int err;
+
+	/* Depending on the given can_bittiming parameter structure the CAN
+	 * timing parameters are calculated based on the provided bitrate OR
+	 * alternatively the CAN timing parameters (tq, prop_seg, etc.) are
+	 * provided directly which are then checked and fixed up.
+	 */
+	if (!bt->tq && bt->bitrate && btc)
+		err = can_calc_bittiming(dev, bt, btc);
+	else if (bt->tq && !bt->bitrate && btc)
+		err = can_fixup_bittiming(dev, bt, btc);
+	else if (!bt->tq && bt->bitrate && bitrate_const)
+		err = can_validate_bitrate(dev, bt, bitrate_const,
+					   bitrate_const_cnt);
+	else
+		err = -EINVAL;
+
+	return err;
+}

drivers/net/can/dev/length.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2012, 2020 Oliver Hartkopp <socketcan@hartkopp.net>
+ */
+
+#include <linux/can/dev.h>
+
+/* CAN DLC to real data length conversion helpers */
+
+static const u8 dlc2len[] = {
+	0, 1, 2, 3, 4, 5, 6, 7,
+	8, 12, 16, 20, 24, 32, 48, 64
+};
+
+/* get data length from raw data length code (DLC) */
+u8 can_fd_dlc2len(u8 dlc)
+{
+	return dlc2len[dlc & 0x0F];
+}
+EXPORT_SYMBOL_GPL(can_fd_dlc2len);
+
+static const u8 len2dlc[] = {
+	0, 1, 2, 3, 4, 5, 6, 7, 8,	/* 0 - 8 */
+	9, 9, 9, 9,			/* 9 - 12 */
+	10, 10, 10, 10,			/* 13 - 16 */
+	11, 11, 11, 11,			/* 17 - 20 */
+	12, 12, 12, 12,			/* 21 - 24 */
+	13, 13, 13, 13, 13, 13, 13, 13,	/* 25 - 32 */
+	14, 14, 14, 14, 14, 14, 14, 14,	/* 33 - 40 */
+	14, 14, 14, 14, 14, 14, 14, 14,	/* 41 - 48 */
+};
+
+/* map the sanitized data length to an appropriate data length code */
+u8 can_fd_len2dlc(u8 len)
+{
+	if (len >= ARRAY_SIZE(len2dlc))
+		return CANFD_MAX_DLC;
+
+	return len2dlc[len];
+}
+EXPORT_SYMBOL_GPL(can_fd_len2dlc);
+
+/**
+ * can_skb_get_frame_len() - Calculate the CAN Frame length in bytes
+ * 	of a given skb.
+ * @skb: socket buffer of a CAN message.
+ *
+ * Do a rough calculation: bit stuffing is ignored and length in bits
+ * is rounded up to a length in bytes.
+ *
+ * Rationale: this function is to be used for the BQL functions
+ * (netdev_sent_queue() and netdev_completed_queue()) which expect a
+ * value in bytes. Just using skb->len is insufficient because it will
+ * return the constant value of CAN(FD)_MTU. Doing the bit stuffing
+ * calculation would be too expensive in term of computing resources
+ * for no noticeable gain.
+ *
+ * Remarks: The payload of CAN FD frames with BRS flag are sent at a
+ * different bitrate. Currently, the can-utils canbusload tool does
+ * not support CAN-FD yet and so we could not run any benchmark to
+ * measure the impact. There might be possible improvement here.
+ *
+ * Return: length in bytes.
+ */
+unsigned int can_skb_get_frame_len(const struct sk_buff *skb)
+{
+	const struct canfd_frame *cf = (const struct canfd_frame *)skb->data;
+	u8 len;
+
+	if (can_is_canfd_skb(skb))
+		len = canfd_sanitize_len(cf->len);
+	else if (cf->can_id & CAN_RTR_FLAG)
+		len = 0;
+	else
+		len = cf->len;
+
+	if (can_is_canfd_skb(skb)) {
+		if (cf->can_id & CAN_EFF_FLAG)
+			len += CANFD_FRAME_OVERHEAD_EFF;
+		else
+			len += CANFD_FRAME_OVERHEAD_SFF;
+	} else {
+		if (cf->can_id & CAN_EFF_FLAG)
+			len += CAN_FRAME_OVERHEAD_EFF;
+		else
+			len += CAN_FRAME_OVERHEAD_SFF;
+	}
+
+	return len;
+}
+EXPORT_SYMBOL_GPL(can_skb_get_frame_len);

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

@@ -263,7 +263,8 @@ int can_rx_offload_queue_sorted(struct can_rx_offload *offload,
 EXPORT_SYMBOL_GPL(can_rx_offload_queue_sorted);
 
 unsigned int can_rx_offload_get_echo_skb(struct can_rx_offload *offload,
-					 unsigned int idx, u32 timestamp)
+					 unsigned int idx, u32 timestamp,
+					 unsigned int *frame_len_ptr)
 {
 	struct net_device *dev = offload->dev;
 	struct net_device_stats *stats = &dev->stats;
@@ -271,7 +272,7 @@ unsigned int can_rx_offload_get_echo_skb(struct can_rx_offload *offload,
 	u8 len;
 	int err;
 
-	skb = __can_get_echo_skb(dev, idx, &len);
+	skb = __can_get_echo_skb(dev, idx, &len, frame_len_ptr);
 	if (!skb)
 		return 0;
 

drivers/net/can/dev/skb.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
+ * Copyright (C) 2006 Andrey Volkov, Varma Electronics
+ * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
+ */
+
+#include <linux/can/dev.h>
+
+/* Local echo of CAN messages
+ *
+ * CAN network devices *should* support a local echo functionality
+ * (see Documentation/networking/can.rst). To test the handling of CAN
+ * interfaces that do not support the local echo both driver types are
+ * implemented. In the case that the driver does not support the echo
+ * the IFF_ECHO remains clear in dev->flags. This causes the PF_CAN core
+ * to perform the echo as a fallback solution.
+ */
+void can_flush_echo_skb(struct net_device *dev)
+{
+	struct can_priv *priv = netdev_priv(dev);
+	struct net_device_stats *stats = &dev->stats;
+	int i;
+
+	for (i = 0; i < priv->echo_skb_max; i++) {
+		if (priv->echo_skb[i]) {
+			kfree_skb(priv->echo_skb[i]);
+			priv->echo_skb[i] = NULL;
+			stats->tx_dropped++;
+			stats->tx_aborted_errors++;
+		}
+	}
+}
+
+/* Put the skb on the stack to be looped backed locally lateron
+ *
+ * The function is typically called in the start_xmit function
+ * of the device driver. The driver must protect access to
+ * priv->echo_skb, if necessary.
+ */
+int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
+		     unsigned int idx, unsigned int frame_len)
+{
+	struct can_priv *priv = netdev_priv(dev);
+
+	BUG_ON(idx >= priv->echo_skb_max);
+
+	/* check flag whether this packet has to be looped back */
+	if (!(dev->flags & IFF_ECHO) || skb->pkt_type != PACKET_LOOPBACK ||
+	    (skb->protocol != htons(ETH_P_CAN) &&
+	     skb->protocol != htons(ETH_P_CANFD))) {
+		kfree_skb(skb);
+		return 0;
+	}
+
+	if (!priv->echo_skb[idx]) {
+		skb = can_create_echo_skb(skb);
+		if (!skb)
+			return -ENOMEM;
+
+		/* make settings for echo to reduce code in irq context */
+		skb->pkt_type = PACKET_BROADCAST;
+		skb->ip_summed = CHECKSUM_UNNECESSARY;
+		skb->dev = dev;
+
+		/* save frame_len to reuse it when transmission is completed */
+		can_skb_prv(skb)->frame_len = frame_len;
+
+		skb_tx_timestamp(skb);
+
+		/* save this skb for tx interrupt echo handling */
+		priv->echo_skb[idx] = skb;
+	} else {
+		/* locking problem with netif_stop_queue() ?? */
+		netdev_err(dev, "%s: BUG! echo_skb %d is occupied!\n", __func__, idx);
+		kfree_skb(skb);
+		return -EBUSY;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(can_put_echo_skb);
+
+struct sk_buff *
+__can_get_echo_skb(struct net_device *dev, unsigned int idx, u8 *len_ptr,
+		   unsigned int *frame_len_ptr)
+{
+	struct can_priv *priv = netdev_priv(dev);
+
+	if (idx >= priv->echo_skb_max) {
+		netdev_err(dev, "%s: BUG! Trying to access can_priv::echo_skb out of bounds (%u/max %u)\n",
+			   __func__, idx, priv->echo_skb_max);
+		return NULL;
+	}
+
+	if (priv->echo_skb[idx]) {
+		/* Using "struct canfd_frame::len" for the frame
+		 * length is supported on both CAN and CANFD frames.
+		 */
+		struct sk_buff *skb = priv->echo_skb[idx];
+		struct can_skb_priv *can_skb_priv = can_skb_prv(skb);
+		struct canfd_frame *cf = (struct canfd_frame *)skb->data;
+
+		/* get the real payload length for netdev statistics */
+		if (cf->can_id & CAN_RTR_FLAG)
+			*len_ptr = 0;
+		else
+			*len_ptr = cf->len;
+
+		if (frame_len_ptr)
+			*frame_len_ptr = can_skb_priv->frame_len;
+
+		priv->echo_skb[idx] = NULL;
+
+		return skb;
+	}
+
+	return NULL;
+}
+
+/* Get the skb from the stack and loop it back locally
+ *
+ * The function is typically called when the TX done interrupt
+ * is handled in the device driver. The driver must protect
+ * access to priv->echo_skb, if necessary.
+ */
+unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx,
+			      unsigned int *frame_len_ptr)
+{
+	struct sk_buff *skb;
+	u8 len;
+
+	skb = __can_get_echo_skb(dev, idx, &len, frame_len_ptr);
+	if (!skb)
+		return 0;
+
+	skb_get(skb);
+	if (netif_rx(skb) == NET_RX_SUCCESS)
+		dev_consume_skb_any(skb);
+	else
+		dev_kfree_skb_any(skb);
+
+	return len;
+}
+EXPORT_SYMBOL_GPL(can_get_echo_skb);
+
+/* Remove the skb from the stack and free it.
+ *
+ * The function is typically called when TX failed.
+ */
+void can_free_echo_skb(struct net_device *dev, unsigned int idx)
+{
+	struct can_priv *priv = netdev_priv(dev);
+
+	BUG_ON(idx >= priv->echo_skb_max);
+
+	if (priv->echo_skb[idx]) {
+		dev_kfree_skb_any(priv->echo_skb[idx]);
+		priv->echo_skb[idx] = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(can_free_echo_skb);
+
+struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
+{
+	struct sk_buff *skb;
+
+	skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
+			       sizeof(struct can_frame));
+	if (unlikely(!skb))
+		return NULL;
+
+	skb->protocol = htons(ETH_P_CAN);
+	skb->pkt_type = PACKET_BROADCAST;
+	skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+	skb_reset_mac_header(skb);
+	skb_reset_network_header(skb);
+	skb_reset_transport_header(skb);
+
+	can_skb_reserve(skb);
+	can_skb_prv(skb)->ifindex = dev->ifindex;
+	can_skb_prv(skb)->skbcnt = 0;
+
+	*cf = skb_put_zero(skb, sizeof(struct can_frame));
+
+	return skb;
+}
+EXPORT_SYMBOL_GPL(alloc_can_skb);
+
+struct sk_buff *alloc_canfd_skb(struct net_device *dev,
+				struct canfd_frame **cfd)
+{
+	struct sk_buff *skb;
+
+	skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
+			       sizeof(struct canfd_frame));
+	if (unlikely(!skb))
+		return NULL;
+
+	skb->protocol = htons(ETH_P_CANFD);
+	skb->pkt_type = PACKET_BROADCAST;
+	skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+	skb_reset_mac_header(skb);
+	skb_reset_network_header(skb);
+	skb_reset_transport_header(skb);
+
+	can_skb_reserve(skb);
+	can_skb_prv(skb)->ifindex = dev->ifindex;
+	can_skb_prv(skb)->skbcnt = 0;
+
+	*cfd = skb_put_zero(skb, sizeof(struct canfd_frame));
+
+	return skb;
+}
+EXPORT_SYMBOL_GPL(alloc_canfd_skb);
+
+struct sk_buff *alloc_can_err_skb(struct net_device *dev, struct can_frame **cf)
+{
+	struct sk_buff *skb;
+
+	skb = alloc_can_skb(dev, cf);
+	if (unlikely(!skb))
+		return NULL;
+
+	(*cf)->can_id = CAN_ERR_FLAG;
+	(*cf)->len = CAN_ERR_DLC;
+
+	return skb;
+}
+EXPORT_SYMBOL_GPL(alloc_can_err_skb);

drivers/net/can/flexcan.c

@@ -815,7 +815,7 @@ static netdev_tx_t flexcan_start_xmit(struct sk_buff *skb, struct net_device *de
 		priv->write(data, &priv->tx_mb->data[i / sizeof(u32)]);
 	}
 
-	can_put_echo_skb(skb, dev, 0);
+	can_put_echo_skb(skb, dev, 0, 0);
 
 	priv->write(can_id, &priv->tx_mb->can_id);
 	priv->write(ctrl, &priv->tx_mb->can_ctrl);
@@ -1122,8 +1122,9 @@ static irqreturn_t flexcan_irq(int irq, void *dev_id)
 		u32 reg_ctrl = priv->read(&priv->tx_mb->can_ctrl);
 
 		handled = IRQ_HANDLED;
-		stats->tx_bytes += can_rx_offload_get_echo_skb(&priv->offload,
-							       0, reg_ctrl << 16);
+		stats->tx_bytes +=
+			can_rx_offload_get_echo_skb(&priv->offload, 0,
+						    reg_ctrl << 16, NULL);
 		stats->tx_packets++;
 		can_led_event(dev, CAN_LED_EVENT_TX);
 

drivers/net/can/grcan.c

@@ -517,7 +517,7 @@ static int catch_up_echo_skb(struct net_device *dev, int budget, bool echo)
 			stats->tx_packets++;
 			stats->tx_bytes += priv->txdlc[i];
 			priv->txdlc[i] = 0;
-			can_get_echo_skb(dev, i);
+			can_get_echo_skb(dev, i, NULL);
 		} else {
 			/* For cleanup of untransmitted messages */
 			can_free_echo_skb(dev, i);
@@ -1448,7 +1448,7 @@ static netdev_tx_t grcan_start_xmit(struct sk_buff *skb,
 	 * taken.
 	 */
 	priv->txdlc[slotindex] = cf->len; /* Store dlc for statistics */
-	can_put_echo_skb(skb, dev, slotindex);
+	can_put_echo_skb(skb, dev, slotindex, 0);
 
 	/* Make sure everything is written before allowing hardware to
 	 * read from the memory

drivers/net/can/ifi_canfd/ifi_canfd.c

@@ -629,7 +629,7 @@ static irqreturn_t ifi_canfd_isr(int irq, void *dev_id)
 
 	/* TX IRQ */
 	if (isr & IFI_CANFD_INTERRUPT_TXFIFO_REMOVE) {
-		stats->tx_bytes += can_get_echo_skb(ndev, 0);
+		stats->tx_bytes += can_get_echo_skb(ndev, 0, NULL);
 		stats->tx_packets++;
 		can_led_event(ndev, CAN_LED_EVENT_TX);
 	}
@@ -922,7 +922,7 @@ static netdev_tx_t ifi_canfd_start_xmit(struct sk_buff *skb,
 	writel(0, priv->base + IFI_CANFD_TXFIFO_REPEATCOUNT);
 	writel(0, priv->base + IFI_CANFD_TXFIFO_SUSPEND_US);
 
-	can_put_echo_skb(skb, ndev, 0);
+	can_put_echo_skb(skb, ndev, 0, 0);
 
 	/* Start the transmission */
 	writel(IFI_CANFD_TXSTCMD_ADD_MSG, priv->base + IFI_CANFD_TXSTCMD);

drivers/net/can/kvaser_pciefd.c

@@ -778,7 +778,7 @@ static netdev_tx_t kvaser_pciefd_start_xmit(struct sk_buff *skb,
 	spin_lock_irqsave(&can->echo_lock, irq_flags);
 
 	/* Prepare and save echo skb in internal slot */
-	can_put_echo_skb(skb, netdev, can->echo_idx);
+	can_put_echo_skb(skb, netdev, can->echo_idx, 0);
 
 	/* Move echo index to the next slot */
 	can->echo_idx = (can->echo_idx + 1) % can->can.echo_skb_max;
@@ -1467,7 +1467,7 @@ static int kvaser_pciefd_handle_eack_packet(struct kvaser_pciefd *pcie,
 				  can->reg_base + KVASER_PCIEFD_KCAN_CTRL_REG);
 	} else {
 		int echo_idx = p->header[0] & KVASER_PCIEFD_PACKET_SEQ_MSK;
-		int dlc = can_get_echo_skb(can->can.dev, echo_idx);
+		int dlc = can_get_echo_skb(can->can.dev, echo_idx, NULL);
 		struct net_device_stats *stats = &can->can.dev->stats;
 
 		stats->tx_bytes += dlc;
@@ -1533,7 +1533,7 @@ static int kvaser_pciefd_handle_ack_packet(struct kvaser_pciefd *pcie,
 		netdev_dbg(can->can.dev, "Packet was flushed\n");
 	} else {
 		int echo_idx = p->header[0] & KVASER_PCIEFD_PACKET_SEQ_MSK;
-		int dlc = can_get_echo_skb(can->can.dev, echo_idx);
+		int dlc = can_get_echo_skb(can->can.dev, echo_idx, NULL);
 		u8 count = ioread32(can->reg_base +
 				    KVASER_PCIEFD_KCAN_TX_NPACKETS_REG) & 0xff;
 

drivers/net/can/m_can/m_can.c

@@ -930,7 +930,7 @@ static void m_can_echo_tx_event(struct net_device *dev)
 						(fgi << TXEFA_EFAI_SHIFT)));
 
 		/* update stats */
-		stats->tx_bytes += can_get_echo_skb(dev, msg_mark);
+		stats->tx_bytes += can_get_echo_skb(dev, msg_mark, NULL);
 		stats->tx_packets++;
 	}
 }
@@ -972,7 +972,7 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
 	if (cdev->version == 30) {
 		if (ir & IR_TC) {
 			/* Transmission Complete Interrupt*/
-			stats->tx_bytes += can_get_echo_skb(dev, 0);
+			stats->tx_bytes += can_get_echo_skb(dev, 0, NULL);
 			stats->tx_packets++;
 			can_led_event(dev, CAN_LED_EVENT_TX);
 			netif_wake_queue(dev);
@@ -1483,7 +1483,7 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 					 M_CAN_FIFO_DATA(i / 4),
 					 *(u32 *)(cf->data + i));
 
-		can_put_echo_skb(skb, dev, 0);
+		can_put_echo_skb(skb, dev, 0, 0);
 
 		if (cdev->can.ctrlmode & CAN_CTRLMODE_FD) {
 			cccr = m_can_read(cdev, M_CAN_CCCR);
@@ -1554,7 +1554,7 @@ 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);
+		can_put_echo_skb(skb, dev, putidx, 0);
 
 		/* Enable TX FIFO element to start transfer  */
 		m_can_write(cdev, M_CAN_TXBAR, (1 << putidx));

drivers/net/can/m_can/tcan4x5x.h

@@ -25,7 +25,7 @@ struct __packed tcan4x5x_buf_cmd {
 	u8 len;
 };
 
-struct __packed tcan4x5x_map_buf {
+struct tcan4x5x_map_buf {
 	struct tcan4x5x_buf_cmd cmd;
 	u8 data[256 * sizeof(u32)];
 } ____cacheline_aligned;

drivers/net/can/mscan/mscan.c

@@ -270,7 +270,7 @@ static netdev_tx_t mscan_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	list_add_tail(&priv->tx_queue[buf_id].list, &priv->tx_head);
 
-	can_put_echo_skb(skb, dev, buf_id);
+	can_put_echo_skb(skb, dev, buf_id, 0);
 
 	/* Enable interrupt. */
 	priv->tx_active |= 1 << buf_id;
@@ -448,7 +448,7 @@ static irqreturn_t mscan_isr(int irq, void *dev_id)
 			out_8(&regs->cantbsel, mask);
 			stats->tx_bytes += in_8(&regs->tx.dlr);
 			stats->tx_packets++;
-			can_get_echo_skb(dev, entry->id);
+			can_get_echo_skb(dev, entry->id, NULL);
 			priv->tx_active &= ~mask;
 			list_del(pos);
 		}

drivers/net/can/pch_can.c

@@ -711,7 +711,7 @@ static void pch_can_tx_complete(struct net_device *ndev, u32 int_stat)
 	struct net_device_stats *stats = &(priv->ndev->stats);
 	u32 dlc;
 
-	can_get_echo_skb(ndev, int_stat - PCH_RX_OBJ_END - 1);
+	can_get_echo_skb(ndev, int_stat - PCH_RX_OBJ_END - 1, NULL);
 	iowrite32(PCH_CMASK_RX_TX_GET | PCH_CMASK_CLRINTPND,
 		  &priv->regs->ifregs[1].cmask);
 	pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, int_stat);
@@ -924,7 +924,7 @@ static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev)
 			  &priv->regs->ifregs[1].data[i / 2]);
 	}
 
-	can_put_echo_skb(skb, ndev, tx_obj_no - PCH_RX_OBJ_END - 1);
+	can_put_echo_skb(skb, ndev, tx_obj_no - PCH_RX_OBJ_END - 1, 0);
 
 	/* Set the size of the data. Update if2_mcont */
 	iowrite32(cf->len | PCH_IF_MCONT_NEWDAT | PCH_IF_MCONT_TXRQXT |

drivers/net/can/peak_canfd/peak_canfd.c

@@ -266,7 +266,7 @@ static int pucan_handle_can_rx(struct peak_canfd_priv *priv,
 		unsigned long flags;
 
 		spin_lock_irqsave(&priv->echo_lock, flags);
-		can_get_echo_skb(priv->ndev, msg->client);
+		can_get_echo_skb(priv->ndev, msg->client, NULL);
 
 		/* count bytes of the echo instead of skb */
 		stats->tx_bytes += cf_len;
@@ -716,7 +716,7 @@ static netdev_tx_t peak_canfd_start_xmit(struct sk_buff *skb,
 	spin_lock_irqsave(&priv->echo_lock, flags);
 
 	/* prepare and save echo skb in internal slot */
-	can_put_echo_skb(skb, ndev, priv->echo_idx);
+	can_put_echo_skb(skb, ndev, priv->echo_idx, 0);
 
 	/* move echo index to the next slot */
 	priv->echo_idx = (priv->echo_idx + 1) % priv->can.echo_skb_max;

drivers/net/can/rcar/rcar_can.c

@@ -386,7 +386,7 @@ static void rcar_can_tx_done(struct net_device *ndev)
 		stats->tx_bytes += priv->tx_dlc[priv->tx_tail %
 						RCAR_CAN_FIFO_DEPTH];
 		priv->tx_dlc[priv->tx_tail % RCAR_CAN_FIFO_DEPTH] = 0;
-		can_get_echo_skb(ndev, priv->tx_tail % RCAR_CAN_FIFO_DEPTH);
+		can_get_echo_skb(ndev, priv->tx_tail % RCAR_CAN_FIFO_DEPTH, NULL);
 		priv->tx_tail++;
 		netif_wake_queue(ndev);
 	}
@@ -617,7 +617,7 @@ static netdev_tx_t rcar_can_start_xmit(struct sk_buff *skb,
 	writeb(cf->len, &priv->regs->mb[RCAR_CAN_TX_FIFO_MBX].dlc);
 
 	priv->tx_dlc[priv->tx_head % RCAR_CAN_FIFO_DEPTH] = cf->len;
-	can_put_echo_skb(skb, ndev, priv->tx_head % RCAR_CAN_FIFO_DEPTH);
+	can_put_echo_skb(skb, ndev, priv->tx_head % RCAR_CAN_FIFO_DEPTH, 0);
 	priv->tx_head++;
 	/* Start Tx: write 0xff to the TFPCR register to increment
 	 * the CPU-side pointer for the transmit FIFO to the next

drivers/net/can/rcar/rcar_canfd.c

@@ -1044,7 +1044,7 @@ static void rcar_canfd_tx_done(struct net_device *ndev)
 		stats->tx_packets++;
 		stats->tx_bytes += priv->tx_len[sent];
 		priv->tx_len[sent] = 0;
-		can_get_echo_skb(ndev, sent);
+		can_get_echo_skb(ndev, sent, NULL);
 
 		spin_lock_irqsave(&priv->tx_lock, flags);
 		priv->tx_tail++;
@@ -1390,7 +1390,7 @@ static netdev_tx_t rcar_canfd_start_xmit(struct sk_buff *skb,
 	}
 
 	priv->tx_len[priv->tx_head % RCANFD_FIFO_DEPTH] = cf->len;
-	can_put_echo_skb(skb, ndev, priv->tx_head % RCANFD_FIFO_DEPTH);
+	can_put_echo_skb(skb, ndev, priv->tx_head % RCANFD_FIFO_DEPTH, 0);
 
 	spin_lock_irqsave(&priv->tx_lock, flags);
 	priv->tx_head++;

drivers/net/can/sja1000/sja1000.c

@@ -318,7 +318,7 @@ static netdev_tx_t sja1000_start_xmit(struct sk_buff *skb,
 	for (i = 0; i < cf->len; i++)
 		priv->write_reg(priv, dreg++, cf->data[i]);
 
-	can_put_echo_skb(skb, dev, 0);
+	can_put_echo_skb(skb, dev, 0, 0);
 
 	if (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT)
 		cmd_reg_val |= CMD_AT;
@@ -531,7 +531,7 @@ irqreturn_t sja1000_interrupt(int irq, void *dev_id)
 				stats->tx_bytes +=
 					priv->read_reg(priv, SJA1000_FI) & 0xf;
 				stats->tx_packets++;
-				can_get_echo_skb(dev, 0);
+				can_get_echo_skb(dev, 0, NULL);
 			}
 			netif_wake_queue(dev);
 			can_led_event(dev, CAN_LED_EVENT_TX);

drivers/net/can/softing/softing_main.c

@@ -104,7 +104,7 @@ static netdev_tx_t softing_netdev_start_xmit(struct sk_buff *skb,
 	card->tx.last_bus = priv->index;
 	++card->tx.pending;
 	++priv->tx.pending;
-	can_put_echo_skb(skb, dev, priv->tx.echo_put);
+	can_put_echo_skb(skb, dev, priv->tx.echo_put, 0);
 	++priv->tx.echo_put;
 	if (priv->tx.echo_put >= TX_ECHO_SKB_MAX)
 		priv->tx.echo_put = 0;
@@ -284,7 +284,7 @@ static int softing_handle_1(struct softing *card)
 			skb = priv->can.echo_skb[priv->tx.echo_get];
 			if (skb)
 				skb->tstamp = ktime;
-			can_get_echo_skb(netdev, priv->tx.echo_get);
+			can_get_echo_skb(netdev, priv->tx.echo_get, NULL);
 			++priv->tx.echo_get;
 			if (priv->tx.echo_get >= TX_ECHO_SKB_MAX)
 				priv->tx.echo_get = 0;

drivers/net/can/spi/hi311x.c

@@ -586,7 +586,7 @@ static void hi3110_tx_work_handler(struct work_struct *ws)
 			frame = (struct can_frame *)priv->tx_skb->data;
 			hi3110_hw_tx(spi, frame);
 			priv->tx_len = 1 + frame->len;
-			can_put_echo_skb(priv->tx_skb, net, 0);
+			can_put_echo_skb(priv->tx_skb, net, 0, 0);
 			priv->tx_skb = NULL;
 		}
 	}
@@ -725,7 +725,7 @@ static irqreturn_t hi3110_can_ist(int irq, void *dev_id)
 			net->stats.tx_bytes += priv->tx_len - 1;
 			can_led_event(net, CAN_LED_EVENT_TX);
 			if (priv->tx_len) {
-				can_get_echo_skb(net, 0);
+				can_get_echo_skb(net, 0, NULL);
 				priv->tx_len = 0;
 			}
 			netif_wake_queue(net);

drivers/net/can/spi/mcp251x.c

@@ -1002,7 +1002,7 @@ static void mcp251x_tx_work_handler(struct work_struct *ws)
 				frame->len = CAN_FRAME_MAX_DATA_LEN;
 			mcp251x_hw_tx(spi, frame, 0);
 			priv->tx_len = 1 + frame->len;
-			can_put_echo_skb(priv->tx_skb, net, 0);
+			can_put_echo_skb(priv->tx_skb, net, 0, 0);
 			priv->tx_skb = NULL;
 		}
 	}
@@ -1171,7 +1171,7 @@ static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
 			net->stats.tx_bytes += priv->tx_len - 1;
 			can_led_event(net, CAN_LED_EVENT_TX);
 			if (priv->tx_len) {
-				can_get_echo_skb(net, 0);
+				can_get_echo_skb(net, 0, NULL);
 				priv->tx_len = 0;
 			}
 			netif_wake_queue(net);

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

@@ -1271,7 +1271,7 @@ mcp251xfd_handle_tefif_one(struct mcp251xfd_priv *priv,
 	stats->tx_bytes +=
 		can_rx_offload_get_echo_skb(&priv->offload,
 					    mcp251xfd_get_tef_tail(priv),
-					    hw_tef_obj->ts);
+					    hw_tef_obj->ts, NULL);
 	stats->tx_packets++;
 	priv->tef->tail++;
 
@@ -2436,7 +2436,7 @@ static netdev_tx_t mcp251xfd_start_xmit(struct sk_buff *skb,
 	if (tx_ring->head - tx_ring->tail >= tx_ring->obj_num)
 		netif_stop_queue(ndev);
 
-	can_put_echo_skb(skb, ndev, tx_head);
+	can_put_echo_skb(skb, ndev, tx_head, 0);
 
 	err = mcp251xfd_tx_obj_write(priv, tx_obj);
 	if (err)

drivers/net/can/sun4i_can.c

@@ -448,7 +448,7 @@ static netdev_tx_t sun4ican_start_xmit(struct sk_buff *skb, struct net_device *d
 
 	writel(msg_flag_n, priv->base + SUN4I_REG_BUF0_ADDR);
 
-	can_put_echo_skb(skb, dev, 0);
+	can_put_echo_skb(skb, dev, 0, 0);
 
 	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
 		sun4i_can_write_cmdreg(priv, SUN4I_CMD_SELF_RCV_REQ);
@@ -655,7 +655,7 @@ static irqreturn_t sun4i_can_interrupt(int irq, void *dev_id)
 			    readl(priv->base +
 				  SUN4I_REG_RBUF_RBACK_START_ADDR) & 0xf;
 			stats->tx_packets++;
-			can_get_echo_skb(dev, 0);
+			can_get_echo_skb(dev, 0, NULL);
 			netif_wake_queue(dev);
 			can_led_event(dev, CAN_LED_EVENT_TX);
 		}

drivers/net/can/ti_hecc.c

@@ -513,7 +513,7 @@ static netdev_tx_t ti_hecc_xmit(struct sk_buff *skb, struct net_device *ndev)
 			       be32_to_cpu(*(__be32 *)(cf->data + 4)));
 	else
 		*(u32 *)(cf->data + 4) = 0;
-	can_put_echo_skb(skb, ndev, mbxno);
+	can_put_echo_skb(skb, ndev, mbxno, 0);
 
 	spin_lock_irqsave(&priv->mbx_lock, flags);
 	--priv->tx_head;
@@ -757,7 +757,7 @@ static irqreturn_t ti_hecc_interrupt(int irq, void *dev_id)
 			stamp = hecc_read_stamp(priv, mbxno);
 			stats->tx_bytes +=
 				can_rx_offload_get_echo_skb(&priv->offload,
-							    mbxno, stamp);
+							    mbxno, stamp, NULL);
 			stats->tx_packets++;
 			can_led_event(ndev, CAN_LED_EVENT_TX);
 			--priv->tx_tail;

drivers/net/can/usb/ems_usb.c

@@ -518,7 +518,7 @@ static void ems_usb_write_bulk_callback(struct urb *urb)
 	netdev->stats.tx_packets++;
 	netdev->stats.tx_bytes += context->dlc;
 
-	can_get_echo_skb(netdev, context->echo_index);
+	can_get_echo_skb(netdev, context->echo_index, NULL);
 
 	/* Release context */
 	context->echo_index = MAX_TX_URBS;
@@ -801,7 +801,7 @@ static netdev_tx_t ems_usb_start_xmit(struct sk_buff *skb, struct net_device *ne
 	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 	usb_anchor_urb(urb, &dev->tx_submitted);
 
-	can_put_echo_skb(skb, netdev, context->echo_index);
+	can_put_echo_skb(skb, netdev, context->echo_index, 0);
 
 	atomic_inc(&dev->active_tx_urbs);
 

drivers/net/can/usb/esd_usb2.c

@@ -357,7 +357,7 @@ static void esd_usb2_tx_done_msg(struct esd_usb2_net_priv *priv,
 	if (!msg->msg.txdone.status) {
 		stats->tx_packets++;
 		stats->tx_bytes += context->len;
-		can_get_echo_skb(netdev, context->echo_index);
+		can_get_echo_skb(netdev, context->echo_index, NULL);
 	} else {
 		stats->tx_errors++;
 		can_free_echo_skb(netdev, context->echo_index);
@@ -783,7 +783,7 @@ static netdev_tx_t esd_usb2_start_xmit(struct sk_buff *skb,
 
 	usb_anchor_urb(urb, &priv->tx_submitted);
 
-	can_put_echo_skb(skb, netdev, context->echo_index);
+	can_put_echo_skb(skb, netdev, context->echo_index, 0);
 
 	atomic_inc(&priv->active_tx_jobs);
 

drivers/net/can/usb/gs_usb.c

@@ -370,7 +370,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 			goto resubmit_urb;
 		}
 
-		can_get_echo_skb(netdev, hf->echo_id);
+		can_get_echo_skb(netdev, hf->echo_id, NULL);
 
 		gs_free_tx_context(txc);
 
@@ -525,7 +525,7 @@ static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
 	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 	usb_anchor_urb(urb, &dev->tx_submitted);
 
-	can_put_echo_skb(skb, netdev, idx);
+	can_put_echo_skb(skb, netdev, idx, 0);
 
 	atomic_inc(&dev->active_tx_urbs);
 

drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c

@@ -578,7 +578,7 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb,
 
 	context->priv = priv;
 
-	can_put_echo_skb(skb, netdev, context->echo_index);
+	can_put_echo_skb(skb, netdev, context->echo_index, 0);
 
 	usb_fill_bulk_urb(urb, dev->udev,
 			  usb_sndbulkpipe(dev->udev,

drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c

@@ -1151,7 +1151,7 @@ static void kvaser_usb_hydra_tx_acknowledge(const struct kvaser_usb *dev,
 
 	spin_lock_irqsave(&priv->tx_contexts_lock, irq_flags);
 
-	can_get_echo_skb(priv->netdev, context->echo_index);
+	can_get_echo_skb(priv->netdev, context->echo_index, NULL);
 	context->echo_index = dev->max_tx_urbs;
 	--priv->active_tx_contexts;
 	netif_wake_queue(priv->netdev);

drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c

@@ -594,7 +594,7 @@ static void kvaser_usb_leaf_tx_acknowledge(const struct kvaser_usb *dev,
 
 	spin_lock_irqsave(&priv->tx_contexts_lock, flags);
 
-	can_get_echo_skb(priv->netdev, context->echo_index);
+	can_get_echo_skb(priv->netdev, context->echo_index, NULL);
 	context->echo_index = dev->max_tx_urbs;
 	--priv->active_tx_contexts;
 	netif_wake_queue(priv->netdev);

drivers/net/can/usb/mcba_usb.c

@@ -237,7 +237,7 @@ static void mcba_usb_write_bulk_callback(struct urb *urb)
 		netdev->stats.tx_bytes += ctx->dlc;
 
 		can_led_event(netdev, CAN_LED_EVENT_TX);
-		can_get_echo_skb(netdev, ctx->ndx);
+		can_get_echo_skb(netdev, ctx->ndx, NULL);
 	}
 
 	if (urb->status)
@@ -355,7 +355,7 @@ static netdev_tx_t mcba_usb_start_xmit(struct sk_buff *skb,
 	if (cf->can_id & CAN_RTR_FLAG)
 		usb_msg.dlc |= MCBA_DLC_RTR_MASK;
 
-	can_put_echo_skb(skb, priv->netdev, ctx->ndx);
+	can_put_echo_skb(skb, priv->netdev, ctx->ndx, 0);
 
 	err = mcba_usb_xmit(priv, (struct mcba_usb_msg *)&usb_msg, ctx);
 	if (err)

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

@@ -309,7 +309,7 @@ static void peak_usb_write_bulk_callback(struct urb *urb)
 	}
 
 	/* should always release echo skb and corresponding context */
-	can_get_echo_skb(netdev, context->echo_index);
+	can_get_echo_skb(netdev, context->echo_index, NULL);
 	context->echo_index = PCAN_USB_MAX_TX_URBS;
 
 	/* do wakeup tx queue in case of success only */
@@ -365,7 +365,7 @@ static netdev_tx_t peak_usb_ndo_start_xmit(struct sk_buff *skb,
 
 	usb_anchor_urb(urb, &dev->tx_submitted);
 
-	can_put_echo_skb(skb, netdev, context->echo_index);
+	can_put_echo_skb(skb, netdev, context->echo_index, 0);
 
 	atomic_inc(&dev->active_tx_urbs);
 

drivers/net/can/usb/ucan.c

@@ -672,7 +672,7 @@ static void ucan_tx_complete_msg(struct ucan_priv *up,
 			/* update statistics */
 			up->netdev->stats.tx_packets++;
 			up->netdev->stats.tx_bytes += dlc;
-			can_get_echo_skb(up->netdev, echo_index);
+			can_get_echo_skb(up->netdev, echo_index, NULL);
 		} else {
 			up->netdev->stats.tx_dropped++;
 			can_free_echo_skb(up->netdev, echo_index);
@@ -1137,7 +1137,7 @@ static netdev_tx_t ucan_start_xmit(struct sk_buff *skb,
 
 	/* put the skb on can loopback stack */
 	spin_lock_irqsave(&up->echo_skb_lock, flags);
-	can_put_echo_skb(skb, up->netdev, echo_index);
+	can_put_echo_skb(skb, up->netdev, echo_index, 0);
 	spin_unlock_irqrestore(&up->echo_skb_lock, flags);
 
 	/* transmit it */

drivers/net/can/usb/usb_8dev.c

@@ -585,7 +585,7 @@ static void usb_8dev_write_bulk_callback(struct urb *urb)
 	netdev->stats.tx_packets++;
 	netdev->stats.tx_bytes += context->dlc;
 
-	can_get_echo_skb(netdev, context->echo_index);
+	can_get_echo_skb(netdev, context->echo_index, NULL);
 
 	can_led_event(netdev, CAN_LED_EVENT_TX);
 
@@ -664,7 +664,7 @@ static netdev_tx_t usb_8dev_start_xmit(struct sk_buff *skb,
 	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 	usb_anchor_urb(urb, &priv->tx_submitted);
 
-	can_put_echo_skb(skb, netdev, context->echo_index);
+	can_put_echo_skb(skb, netdev, context->echo_index, 0);
 
 	atomic_inc(&priv->active_tx_urbs);
 

drivers/net/can/xilinx_can.c

@@ -592,9 +592,9 @@ static void xcan_write_frame(struct net_device *ndev, struct sk_buff *skb,
 
 	if (!(priv->devtype.flags & XCAN_FLAG_TX_MAILBOXES) &&
 	    (priv->devtype.flags & XCAN_FLAG_TXFEMP))
-		can_put_echo_skb(skb, ndev, priv->tx_head % priv->tx_max);
+		can_put_echo_skb(skb, ndev, priv->tx_head % priv->tx_max, 0);
 	else
-		can_put_echo_skb(skb, ndev, 0);
+		can_put_echo_skb(skb, ndev, 0, 0);
 
 	priv->tx_head++;
 
@@ -1292,7 +1292,7 @@ static void xcan_tx_interrupt(struct net_device *ndev, u32 isr)
 
 	while (frames_sent--) {
 		stats->tx_bytes += can_get_echo_skb(ndev, priv->tx_tail %
-						    priv->tx_max);
+						    priv->tx_max, NULL);
 		priv->tx_tail++;
 		stats->tx_packets++;
 	}

include/linux/can/bittiming.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (c) 2020 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
+ */
+
+#ifndef _CAN_BITTIMING_H
+#define _CAN_BITTIMING_H
+
+#include <linux/netdevice.h>
+#include <linux/can/netlink.h>
+
+#define CAN_SYNC_SEG 1
+
+#ifdef CONFIG_CAN_CALC_BITTIMING
+int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
+		       const struct can_bittiming_const *btc);
+#else /* !CONFIG_CAN_CALC_BITTIMING */
+static inline int
+can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
+		   const struct can_bittiming_const *btc)
+{
+	netdev_err(dev, "bit-timing calculation not available\n");
+	return -EINVAL;
+}
+#endif /* CONFIG_CAN_CALC_BITTIMING */
+
+int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,
+		      const struct can_bittiming_const *btc,
+		      const u32 *bitrate_const,
+		      const unsigned int bitrate_const_cnt);
+
+/*
+ * can_bit_time() - Duration of one bit
+ *
+ * Please refer to ISO 11898-1:2015, section 11.3.1.1 "Bit time" for
+ * additional information.
+ *
+ * Return: the number of time quanta in one bit.
+ */
+static inline unsigned int can_bit_time(const struct can_bittiming *bt)
+{
+	return CAN_SYNC_SEG + bt->prop_seg + bt->phase_seg1 + bt->phase_seg2;
+}
+
+#endif /* !_CAN_BITTIMING_H */

include/linux/can/dev.h

@@ -15,8 +15,10 @@
 #define _CAN_DEV_H
 
 #include <linux/can.h>
+#include <linux/can/bittiming.h>
 #include <linux/can/error.h>
 #include <linux/can/led.h>
+#include <linux/can/length.h>
 #include <linux/can/netlink.h>
 #include <linux/can/skb.h>
 #include <linux/netdevice.h>
@@ -82,118 +84,6 @@ struct can_priv {
 #endif
 };
 
-#define CAN_SYNC_SEG 1
-
-/*
- * can_bit_time() - Duration of one bit
- *
- * Please refer to ISO 11898-1:2015, section 11.3.1.1 "Bit time" for
- * additional information.
- *
- * Return: the number of time quanta in one bit.
- */
-static inline unsigned int can_bit_time(const struct can_bittiming *bt)
-{
-	return CAN_SYNC_SEG + bt->prop_seg + bt->phase_seg1 + bt->phase_seg2;
-}
-
-/*
- * can_cc_dlc2len(value) - convert a given data length code (dlc) of a
- * Classical CAN frame into a valid data length of max. 8 bytes.
- *
- * To be used in the CAN netdriver receive path to ensure conformance with
- * ISO 11898-1 Chapter 8.4.2.3 (DLC field)
- */
-#define can_cc_dlc2len(dlc)	(min_t(u8, (dlc), CAN_MAX_DLEN))
-
-/* Check for outgoing skbs that have not been created by the CAN subsystem */
-static inline bool can_skb_headroom_valid(struct net_device *dev,
-					  struct sk_buff *skb)
-{
-	/* af_packet creates a headroom of HH_DATA_MOD bytes which is fine */
-	if (WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct can_skb_priv)))
-		return false;
-
-	/* af_packet does not apply CAN skb specific settings */
-	if (skb->ip_summed == CHECKSUM_NONE) {
-		/* init headroom */
-		can_skb_prv(skb)->ifindex = dev->ifindex;
-		can_skb_prv(skb)->skbcnt = 0;
-
-		skb->ip_summed = CHECKSUM_UNNECESSARY;
-
-		/* perform proper loopback on capable devices */
-		if (dev->flags & IFF_ECHO)
-			skb->pkt_type = PACKET_LOOPBACK;
-		else
-			skb->pkt_type = PACKET_HOST;
-
-		skb_reset_mac_header(skb);
-		skb_reset_network_header(skb);
-		skb_reset_transport_header(skb);
-	}
-
-	return true;
-}
-
-/* Drop a given socketbuffer if it does not contain a valid CAN frame. */
-static inline bool can_dropped_invalid_skb(struct net_device *dev,
-					  struct sk_buff *skb)
-{
-	const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
-
-	if (skb->protocol == htons(ETH_P_CAN)) {
-		if (unlikely(skb->len != CAN_MTU ||
-			     cfd->len > CAN_MAX_DLEN))
-			goto inval_skb;
-	} else if (skb->protocol == htons(ETH_P_CANFD)) {
-		if (unlikely(skb->len != CANFD_MTU ||
-			     cfd->len > CANFD_MAX_DLEN))
-			goto inval_skb;
-	} else
-		goto inval_skb;
-
-	if (!can_skb_headroom_valid(dev, skb))
-		goto inval_skb;
-
-	return false;
-
-inval_skb:
-	kfree_skb(skb);
-	dev->stats.tx_dropped++;
-	return true;
-}
-
-static inline bool can_is_canfd_skb(const struct sk_buff *skb)
-{
-	/* the CAN specific type of skb is identified by its data length */
-	return skb->len == CANFD_MTU;
-}
-
-/* helper to get the data length code (DLC) for Classical CAN raw DLC access */
-static inline u8 can_get_cc_dlc(const struct can_frame *cf, const u32 ctrlmode)
-{
-	/* return len8_dlc as dlc value only if all conditions apply */
-	if ((ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC) &&
-	    (cf->len == CAN_MAX_DLEN) &&
-	    (cf->len8_dlc > CAN_MAX_DLEN && cf->len8_dlc <= CAN_MAX_RAW_DLC))
-		return cf->len8_dlc;
-
-	/* return the payload length as dlc value */
-	return cf->len;
-}
-
-/* helper to set len and len8_dlc value for Classical CAN raw DLC access */
-static inline void can_frame_set_cc_len(struct can_frame *cf, const u8 dlc,
-					const u32 ctrlmode)
-{
-	/* the caller already ensured that dlc is a value from 0 .. 15 */
-	if (ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC && dlc > CAN_MAX_DLEN)
-		cf->len8_dlc = dlc;
-
-	/* limit the payload length 'len' to CAN_MAX_DLEN */
-	cf->len = can_cc_dlc2len(dlc);
-}
 
 /* helper to define static CAN controller features at device creation time */
 static inline void can_set_static_ctrlmode(struct net_device *dev,
@@ -210,11 +100,7 @@ static inline void can_set_static_ctrlmode(struct net_device *dev,
 		dev->mtu = CANFD_MTU;
 }
 
-/* get data length from raw data length code (DLC) */
-u8 can_fd_dlc2len(u8 dlc);
-
-/* map the sanitized data length to an appropriate data length code */
-u8 can_fd_len2dlc(u8 len);
+void can_setup(struct net_device *dev);
 
 struct net_device *alloc_candev_mqs(int sizeof_priv, unsigned int echo_skb_max,
 				    unsigned int txqs, unsigned int rxqs);
@@ -240,23 +126,14 @@ void can_bus_off(struct net_device *dev);
 void can_change_state(struct net_device *dev, struct can_frame *cf,
 		      enum can_state tx_state, enum can_state rx_state);
 
-int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
-		     unsigned int idx);
-struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx,
-				   u8 *len_ptr);
-unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx);
-void can_free_echo_skb(struct net_device *dev, unsigned int idx);
-
 #ifdef CONFIG_OF
 void of_can_transceiver(struct net_device *dev);
 #else
 static inline void of_can_transceiver(struct net_device *dev) { }
 #endif
 
-struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
-struct sk_buff *alloc_canfd_skb(struct net_device *dev,
-				struct canfd_frame **cfd);
-struct sk_buff *alloc_can_err_skb(struct net_device *dev,
-				  struct can_frame **cf);
+extern struct rtnl_link_ops can_link_ops;
+int can_netlink_register(void);
+void can_netlink_unregister(void);
 
 #endif /* !_CAN_DEV_H */

include/linux/can/length.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2020 Oliver Hartkopp <socketcan@hartkopp.net>
+ * Copyright (C) 2020 Marc Kleine-Budde <kernel@pengutronix.de>
+ */
+
+#ifndef _CAN_LENGTH_H
+#define _CAN_LENGTH_H
+
+/*
+ * Size of a Classical CAN Standard Frame
+ *
+ * Name of Field			Bits
+ * ---------------------------------------------------------
+ * Start-of-frame			1
+ * Identifier				11
+ * Remote transmission request (RTR)	1
+ * Identifier extension bit (IDE)	1
+ * Reserved bit (r0)			1
+ * Data length code (DLC)		4
+ * Data field				0...64
+ * CRC					15
+ * CRC delimiter			1
+ * ACK slot				1
+ * ACK delimiter			1
+ * End-of-frame (EOF)			7
+ * Inter frame spacing			3
+ *
+ * rounded up and ignoring bitstuffing
+ */
+#define CAN_FRAME_OVERHEAD_SFF DIV_ROUND_UP(47, 8)
+
+/*
+ * Size of a Classical CAN Extended Frame
+ *
+ * Name of Field			Bits
+ * ---------------------------------------------------------
+ * Start-of-frame			1
+ * Identifier A				11
+ * Substitute remote request (SRR)	1
+ * Identifier extension bit (IDE)	1
+ * Identifier B				18
+ * Remote transmission request (RTR)	1
+ * Reserved bits (r1, r0)		2
+ * Data length code (DLC)		4
+ * Data field				0...64
+ * CRC					15
+ * CRC delimiter			1
+ * ACK slot				1
+ * ACK delimiter			1
+ * End-of-frame (EOF)			7
+ * Inter frame spacing			3
+ *
+ * rounded up and ignoring bitstuffing
+ */
+#define CAN_FRAME_OVERHEAD_EFF DIV_ROUND_UP(67, 8)
+
+/*
+ * Size of a CAN-FD Standard Frame
+ *
+ * Name of Field			Bits
+ * ---------------------------------------------------------
+ * Start-of-frame			1
+ * Identifier				11
+ * Reserved bit (r1)			1
+ * Identifier extension bit (IDE)	1
+ * Flexible data rate format (FDF)	1
+ * Reserved bit (r0)			1
+ * Bit Rate Switch (BRS)		1
+ * Error Status Indicator (ESI)		1
+ * Data length code (DLC)		4
+ * Data field				0...512
+ * Stuff Bit Count (SBC)		0...16: 4 20...64:5
+ * CRC					0...16: 17 20...64:21
+ * CRC delimiter (CD)			1
+ * ACK slot (AS)			1
+ * ACK delimiter (AD)			1
+ * End-of-frame (EOF)			7
+ * Inter frame spacing			3
+ *
+ * assuming CRC21, rounded up and ignoring bitstuffing
+ */
+#define CANFD_FRAME_OVERHEAD_SFF DIV_ROUND_UP(61, 8)
+
+/*
+ * Size of a CAN-FD Extended Frame
+ *
+ * Name of Field			Bits
+ * ---------------------------------------------------------
+ * Start-of-frame			1
+ * Identifier A				11
+ * Substitute remote request (SRR)	1
+ * Identifier extension bit (IDE)	1
+ * Identifier B				18
+ * Reserved bit (r1)			1
+ * Flexible data rate format (FDF)	1
+ * Reserved bit (r0)			1
+ * Bit Rate Switch (BRS)		1
+ * Error Status Indicator (ESI)		1
+ * Data length code (DLC)		4
+ * Data field				0...512
+ * Stuff Bit Count (SBC)		0...16: 4 20...64:5
+ * CRC					0...16: 17 20...64:21
+ * CRC delimiter (CD)			1
+ * ACK slot (AS)			1
+ * ACK delimiter (AD)			1
+ * End-of-frame (EOF)			7
+ * Inter frame spacing			3
+ *
+ * assuming CRC21, rounded up and ignoring bitstuffing
+ */
+#define CANFD_FRAME_OVERHEAD_EFF DIV_ROUND_UP(80, 8)
+
+/*
+ * Maximum size of a Classical CAN frame
+ * (rounded up and ignoring bitstuffing)
+ */
+#define CAN_FRAME_LEN_MAX (CAN_FRAME_OVERHEAD_EFF + CAN_MAX_DLEN)
+
+/*
+ * Maximum size of a CAN-FD frame
+ * (rounded up and ignoring bitstuffing)
+ */
+#define CANFD_FRAME_LEN_MAX (CANFD_FRAME_OVERHEAD_EFF + CANFD_MAX_DLEN)
+
+/*
+ * can_cc_dlc2len(value) - convert a given data length code (dlc) of a
+ * Classical CAN frame into a valid data length of max. 8 bytes.
+ *
+ * To be used in the CAN netdriver receive path to ensure conformance with
+ * ISO 11898-1 Chapter 8.4.2.3 (DLC field)
+ */
+#define can_cc_dlc2len(dlc)	(min_t(u8, (dlc), CAN_MAX_DLEN))
+
+/* helper to get the data length code (DLC) for Classical CAN raw DLC access */
+static inline u8 can_get_cc_dlc(const struct can_frame *cf, const u32 ctrlmode)
+{
+	/* return len8_dlc as dlc value only if all conditions apply */
+	if ((ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC) &&
+	    (cf->len == CAN_MAX_DLEN) &&
+	    (cf->len8_dlc > CAN_MAX_DLEN && cf->len8_dlc <= CAN_MAX_RAW_DLC))
+		return cf->len8_dlc;
+
+	/* return the payload length as dlc value */
+	return cf->len;
+}
+
+/* helper to set len and len8_dlc value for Classical CAN raw DLC access */
+static inline void can_frame_set_cc_len(struct can_frame *cf, const u8 dlc,
+					const u32 ctrlmode)
+{
+	/* the caller already ensured that dlc is a value from 0 .. 15 */
+	if (ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC && dlc > CAN_MAX_DLEN)
+		cf->len8_dlc = dlc;
+
+	/* limit the payload length 'len' to CAN_MAX_DLEN */
+	cf->len = can_cc_dlc2len(dlc);
+}
+
+/* get data length from raw data length code (DLC) */
+u8 can_fd_dlc2len(u8 dlc);
+
+/* map the sanitized data length to an appropriate data length code */
+u8 can_fd_len2dlc(u8 len);
+
+/* calculate the CAN Frame length in bytes of a given skb */
+unsigned int can_skb_get_frame_len(const struct sk_buff *skb);
+
+/* map the data length to an appropriate data link layer length */
+static inline u8 canfd_sanitize_len(u8 len)
+{
+	return can_fd_dlc2len(can_fd_len2dlc(len));
+}
+
+#endif /* !_CAN_LENGTH_H */

include/linux/can/rx-offload.h

@@ -44,7 +44,8 @@ int can_rx_offload_irq_offload_fifo(struct can_rx_offload *offload);
 int can_rx_offload_queue_sorted(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 idx, u32 timestamp,
+					 unsigned int *frame_len_ptr);
 int can_rx_offload_queue_tail(struct can_rx_offload *offload,
 			      struct sk_buff *skb);
 void can_rx_offload_del(struct can_rx_offload *offload);

include/linux/can/skb.h

@@ -16,6 +16,20 @@
 #include <linux/can.h>
 #include <net/sock.h>
 
+void can_flush_echo_skb(struct net_device *dev);
+int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
+		     unsigned int idx, unsigned int frame_len);
+struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx,
+				   u8 *len_ptr, unsigned int *frame_len_ptr);
+unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx,
+			      unsigned int *frame_len_ptr);
+void can_free_echo_skb(struct net_device *dev, unsigned int idx);
+struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
+struct sk_buff *alloc_canfd_skb(struct net_device *dev,
+				struct canfd_frame **cfd);
+struct sk_buff *alloc_can_err_skb(struct net_device *dev,
+				  struct can_frame **cf);
+
 /*
  * The struct can_skb_priv is used to transport additional information along
  * with the stored struct can(fd)_frame that can not be contained in existing
@@ -29,11 +43,13 @@
  * struct can_skb_priv - private additional data inside CAN sk_buffs
  * @ifindex:	ifindex of the first interface the CAN frame appeared on
  * @skbcnt:	atomic counter to have an unique id together with skb pointer
+ * @frame_len:	length of CAN frame in data link layer
  * @cf:		align to the following CAN frame at skb->data
  */
 struct can_skb_priv {
 	int ifindex;
 	int skbcnt;
+	unsigned int frame_len;
 	struct can_frame cf[];
 };
 
@@ -74,4 +90,68 @@ static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
 	return nskb;
 }
 
+/* Check for outgoing skbs that have not been created by the CAN subsystem */
+static inline bool can_skb_headroom_valid(struct net_device *dev,
+					  struct sk_buff *skb)
+{
+	/* af_packet creates a headroom of HH_DATA_MOD bytes which is fine */
+	if (WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct can_skb_priv)))
+		return false;
+
+	/* af_packet does not apply CAN skb specific settings */
+	if (skb->ip_summed == CHECKSUM_NONE) {
+		/* init headroom */
+		can_skb_prv(skb)->ifindex = dev->ifindex;
+		can_skb_prv(skb)->skbcnt = 0;
+
+		skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+		/* perform proper loopback on capable devices */
+		if (dev->flags & IFF_ECHO)
+			skb->pkt_type = PACKET_LOOPBACK;
+		else
+			skb->pkt_type = PACKET_HOST;
+
+		skb_reset_mac_header(skb);
+		skb_reset_network_header(skb);
+		skb_reset_transport_header(skb);
+	}
+
+	return true;
+}
+
+/* Drop a given socketbuffer if it does not contain a valid CAN frame. */
+static inline bool can_dropped_invalid_skb(struct net_device *dev,
+					  struct sk_buff *skb)
+{
+	const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
+
+	if (skb->protocol == htons(ETH_P_CAN)) {
+		if (unlikely(skb->len != CAN_MTU ||
+			     cfd->len > CAN_MAX_DLEN))
+			goto inval_skb;
+	} else if (skb->protocol == htons(ETH_P_CANFD)) {
+		if (unlikely(skb->len != CANFD_MTU ||
+			     cfd->len > CANFD_MAX_DLEN))
+			goto inval_skb;
+	} else
+		goto inval_skb;
+
+	if (!can_skb_headroom_valid(dev, skb))
+		goto inval_skb;
+
+	return false;
+
+inval_skb:
+	kfree_skb(skb);
+	dev->stats.tx_dropped++;
+	return true;
+}
+
+static inline bool can_is_canfd_skb(const struct sk_buff *skb)
+{
+	/* the CAN specific type of skb is identified by its data length */
+	return skb->len == CANFD_MTU;
+}
+
 #endif /* !_CAN_SKB_H */