can-dev: implement len8_dlc in some CAN USB adapters for testing

index 3a097c240e5a..fab6ed073e45 100644
@@ -330,10 +330,13 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
 			return;
 
 		cf->can_id = hf->can_id;
 
 		cf->len = can_get_cc_len(hf->len);
+		cf->len8_dlc = can_get_len8_dlc(dev->can.ctrlmode, cf->len,
+						hf->len);
+
 		memcpy(cf->data, hf->data, 8);
 
 		/* ERROR frames tell us information about the controller */
 		if (hf->can_id & CAN_ERR_FLAG)
 			gs_update_state(dev, cf);

@@ -502,11 +505,12 @@ static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
 	hf->channel = dev->channel;
 
 	cf = (struct can_frame *)skb->data;
 
 	hf->can_id = cf->can_id;
-	hf->len = cf->len;
+	hf->len = can_get_cc_dlc(dev->can.ctrlmode, cf->len, cf->len8_dlc);
+
 	memcpy(hf->data, cf->data, cf->len);
 
 	usb_fill_bulk_urb(urb, dev->udev,
 			  usb_sndbulkpipe(dev->udev, GSUSB_ENDPOINT_OUT),
 			  hf,

@@ -856,11 +860,11 @@ static struct gs_can *gs_make_candev(unsigned int channel,
 	dev->can.state = CAN_STATE_STOPPED;
 	dev->can.clock.freq = bt_const->fclk_can;
 	dev->can.bittiming_const = &dev->bt_const;
 	dev->can.do_set_bittiming = gs_usb_set_bittiming;
 
-	dev->can.ctrlmode_supported = 0;
+	dev->can.ctrlmode_supported = CAN_CTRLMODE_CC_LEN8_DLC;
 
 	if (bt_const->feature & GS_CAN_FEATURE_LISTEN_ONLY)
 		dev->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;
 
 	if (bt_const->feature & GS_CAN_FEATURE_LOOP_BACK)

index abecb77e34f2..105a17dc8075 100644
@@ -733,10 +733,12 @@ static int pcan_usb_decode_data(struct pcan_usb_msg_context *mc, u8 status_len)
 
 		cf->can_id = le16_to_cpu(tmp16) >> 5;
 	}
 
 	cf->len = can_get_cc_len(rec_len);
+	cf->len8_dlc = can_get_len8_dlc(mc->pdev->dev.can.ctrlmode, cf->len,
+					rec_len);
 
 	/* Only first packet timestamp is a word */
 	if (pcan_usb_decode_ts(mc, !mc->rec_ts_idx))
 		goto decode_failed;
 

@@ -836,11 +838,12 @@ static int pcan_usb_encode_msg(struct peak_usb_device *dev, struct sk_buff *skb,
 	obuf[1] = 1;
 
 	pc = obuf + PCAN_USB_MSG_HEADER_LEN;
 
 	/* status/len byte */
-	*pc = cf->len;
+	*pc = can_get_cc_dlc(dev->can.ctrlmode, cf->len, cf->len8_dlc);
+
 	if (cf->can_id & CAN_RTR_FLAG)
 		*pc |= PCAN_USB_STATUSLEN_RTR;
 
 	/* can id */
 	if (cf->can_id & CAN_EFF_FLAG) {

@@ -990,11 +993,12 @@ static const struct can_bittiming_const pcan_usb_const = {
 const struct peak_usb_adapter pcan_usb = {
 	.name = "PCAN-USB",
 	.device_id = PCAN_USB_PRODUCT_ID,
 	.ctrl_count = 1,
 	.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY |
-			      CAN_CTRLMODE_BERR_REPORTING,
+			      CAN_CTRLMODE_BERR_REPORTING |
+			      CAN_CTRLMODE_CC_LEN8_DLC,
 	.clock = {
 		.freq = PCAN_USB_CRYSTAL_HZ / 2 ,
 	},
 	.bittiming_const = &pcan_usb_const,
 

index 3e875cdbadac..bd90ce8c3f15 100644
@@ -492,16 +492,21 @@ static int pcan_usb_fd_decode_canmsg(struct pcan_usb_fd_if *usb_if,
 		if (rx_msg_flags & PUCAN_MSG_ERROR_STATE_IND)
 			cfd->flags |= CANFD_ESI;
 
 		cfd->len = can_dlc2len(pucan_msg_get_dlc(rm));
 	} else {
+		struct can_frame *cf;
+
 		/* CAN 2.0 frame case */
 		skb = alloc_can_skb(netdev, (struct can_frame **)&cfd);
 		if (!skb)
 			return -ENOMEM;
 
 		cfd->len = can_get_cc_len(pucan_msg_get_dlc(rm));
+		cf = (struct can_frame *)cfd;
+		cf->len8_dlc = can_get_len8_dlc(dev->can.ctrlmode, cf->len,
+						pucan_msg_get_dlc(rm));
 	}
 
 	cfd->can_id = le32_to_cpu(rm->can_id);
 
 	if (rx_msg_flags & PUCAN_MSG_EXT_ID)

@@ -764,12 +769,14 @@ static int pcan_usb_fd_encode_msg(struct peak_usb_device *dev,
 			tx_msg_flags |= PUCAN_MSG_BITRATE_SWITCH;
 
 		if (cfd->flags & CANFD_ESI)
 			tx_msg_flags |= PUCAN_MSG_ERROR_STATE_IND;
 	} else {
+		struct can_frame *cf = (struct can_frame *)cfd;
+
 		/* CAND 2.0 frames */
-		len = cfd->len;
+		len = can_get_cc_dlc(dev->can.ctrlmode, cf->len, cf->len8_dlc);
 
 		if (cfd->can_id & CAN_RTR_FLAG)
 			tx_msg_flags |= PUCAN_MSG_RTR;
 	}
 

@@ -1033,11 +1040,11 @@ static const struct can_bittiming_const pcan_usb_fd_data_const = {
 
 const struct peak_usb_adapter pcan_usb_fd = {
 	.name = "PCAN-USB FD",
 	.device_id = PCAN_USBFD_PRODUCT_ID,
 	.ctrl_count = PCAN_USBFD_CHANNEL_COUNT,
-	.ctrlmode_supported = CAN_CTRLMODE_FD |
+	.ctrlmode_supported = CAN_CTRLMODE_FD | CAN_CTRLMODE_CC_LEN8_DLC |
 			CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY,
 	.clock = {
 		.freq = PCAN_UFD_CRYSTAL_HZ,
 	},
 	.bittiming_const = &pcan_usb_fd_const,

@@ -1105,11 +1112,11 @@ static const struct can_bittiming_const pcan_usb_chip_data_const = {
 
 const struct peak_usb_adapter pcan_usb_chip = {
 	.name = "PCAN-Chip USB",
 	.device_id = PCAN_USBCHIP_PRODUCT_ID,
 	.ctrl_count = PCAN_USBFD_CHANNEL_COUNT,
-	.ctrlmode_supported = CAN_CTRLMODE_FD |
+	.ctrlmode_supported = CAN_CTRLMODE_FD | CAN_CTRLMODE_CC_LEN8_DLC |
 		CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY,
 	.clock = {
 		.freq = PCAN_UFD_CRYSTAL_HZ,
 	},
 	.bittiming_const = &pcan_usb_chip_const,

@@ -1177,11 +1184,11 @@ static const struct can_bittiming_const pcan_usb_pro_fd_data_const = {
 
 const struct peak_usb_adapter pcan_usb_pro_fd = {
 	.name = "PCAN-USB Pro FD",
 	.device_id = PCAN_USBPROFD_PRODUCT_ID,
 	.ctrl_count = PCAN_USBPROFD_CHANNEL_COUNT,
-	.ctrlmode_supported = CAN_CTRLMODE_FD |
+	.ctrlmode_supported = CAN_CTRLMODE_FD | CAN_CTRLMODE_CC_LEN8_DLC |
 			CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY,
 	.clock = {
 		.freq = PCAN_UFD_CRYSTAL_HZ,
 	},
 	.bittiming_const = &pcan_usb_pro_fd_const,

@@ -1249,11 +1256,11 @@ static const struct can_bittiming_const pcan_usb_x6_data_const = {
 
 const struct peak_usb_adapter pcan_usb_x6 = {
 	.name = "PCAN-USB X6",
 	.device_id = PCAN_USBX6_PRODUCT_ID,
 	.ctrl_count = PCAN_USBPROFD_CHANNEL_COUNT,
-	.ctrlmode_supported = CAN_CTRLMODE_FD |
+	.ctrlmode_supported = CAN_CTRLMODE_FD | CAN_CTRLMODE_CC_LEN8_DLC |
 			CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY,
 	.clock = {
 		.freq = PCAN_UFD_CRYSTAL_HZ,
 	},
 	.bittiming_const = &pcan_usb_x6_const,

index 8aedb2ba37fb..e15650c0663e 100644
@@ -469,10 +469,12 @@ static void usb_8dev_rx_can_msg(struct usb_8dev_priv *priv,
 		if (!skb)
 			return;
 
 		cf->can_id = be32_to_cpu(msg->id);
 		cf->len = can_get_cc_len(msg->dlc & 0xF);
+		cf->len8_dlc = can_get_len8_dlc(priv->can.ctrlmode, cf->len,
+						msg->dlc & 0xF);
 
 		if (msg->flags & USB_8DEV_EXTID)
 			cf->can_id |= CAN_EFF_FLAG;
 
 		if (msg->flags & USB_8DEV_RTR)

@@ -635,11 +637,11 @@ static netdev_tx_t usb_8dev_start_xmit(struct sk_buff *skb,
 
 	if (cf->can_id & CAN_EFF_FLAG)
 		msg->flags |= USB_8DEV_EXTID;
 
 	msg->id = cpu_to_be32(cf->can_id & CAN_ERR_MASK);
-	msg->dlc = cf->len;
+	msg->dlc = can_get_cc_dlc(priv->can.ctrlmode, cf->len, cf->len8_dlc);
 	memcpy(msg->data, cf->data, cf->len);
 	msg->end = USB_8DEV_DATA_END;
 
 	for (i = 0; i < MAX_TX_URBS; i++) {
 		if (priv->tx_contexts[i].echo_index == MAX_TX_URBS) {

@@ -925,12 +927,13 @@ static int usb_8dev_probe(struct usb_interface *intf,
 	priv->can.clock.freq = USB_8DEV_ABP_CLOCK;
 	priv->can.bittiming_const = &usb_8dev_bittiming_const;
 	priv->can.do_set_mode = usb_8dev_set_mode;
 	priv->can.do_get_berr_counter = usb_8dev_get_berr_counter;
 	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
-				      CAN_CTRLMODE_LISTENONLY |
-				      CAN_CTRLMODE_ONE_SHOT;
+				       CAN_CTRLMODE_LISTENONLY |
+				       CAN_CTRLMODE_ONE_SHOT |
+				       CAN_CTRLMODE_CC_LEN8_DLC;
 
 	netdev->netdev_ops = &usb_8dev_netdev_ops;
 
 	netdev->flags |= IFF_ECHO; /* we support local echo */
 

index 45018fbad35f..dd7cc705c81a 100644
@@ -168,10 +168,25 @@ 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;
 }
 
+static inline u8 can_check_len8_dlc(u32 ctrlmode, u8 len, u8 dlc, u8 ret)
+{
+	/* return value for len8_dlc only if all conditions apply */
+	if ((ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC) &&
+	    (len == CAN_MAX_DLEN) &&
+	    (dlc > CAN_MAX_DLEN && dlc <= CAN_MAX_RAW_DLC))
+		ret = dlc;
+
+	/* no valid len8_dlc value -> return provided default value */
+	return ret;
+}
+
+#define can_get_len8_dlc(cm, len, dlc) can_check_len8_dlc(cm, len, dlc, 0)
+#define can_get_cc_dlc(cm, len, dlc) can_check_len8_dlc(cm, len, dlc, len)
+
 /* helper to define static CAN controller features at device creation time */
 static inline void can_set_static_ctrlmode(struct net_device *dev,
 					   u32 static_mode)
 {
 	struct can_priv *priv = netdev_priv(dev);