can: mcba_usb: Add support for Microchip CAN BUS Analyzer

SocketCAN driver for Microchip CAN BUS Analyzer
(http://www.microchip.com/development-tools/)

Changes in v4:
- possible memory leak fixed in mcba_usb_write_bulk_callback
- LED support added
- failure handling in mcba_usb_probe improved
- C99 initializers for structs on stack

Changes in v3:
- improved/simplified CAN ID conversion
- functions for transmission of skb and cmd separated
- fixed/improved netif_stop_queue handling
- style/cosmetic corrections

Changes in v2:
- Termination handling reimplemented to fit new netlink API
(IFLA_CAN_TERMINATION)
- Bitrate handling reimplemented to fit new netlink API
(IFLA_CAN_BITRATE)
- CAN ID conversion refactored (changed from macro to inline functions)
- CAN DLC handling using get_can_dlc()
- Endianness handling for can_speed introduced
- Debugging removed
- Redundant error prints removed
- Style/cosmetic corrections (i.e. macro names, redefs, inits etc.)

Signed-off-by: Remigiusz Kołłątaj <remigiusz.kollataj@mobica.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

3 files changed, 911 insertions, 0 deletions

diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
index 8483a40e7e9e..2d0313eb31c0 100644
--- a/drivers/net/can/usb/Kconfig
+++ b/drivers/net/can/usb/Kconfig
@@ -81,4 +81,10 @@ config CAN_8DEV_USB
 	  This driver supports the USB2CAN interface
 	  from 8 devices (http://www.8devices.com).
 
+config CAN_MCBA_USB
+	tristate "Microchip CAN BUS Analyzer interface"
+	---help---
+	  This driver supports the CAN BUS Analyzer interface
+	  from Microchip (http://www.microchip.com/development-tools/).
+
 endmenu
diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
index a64cf983fb87..164453fd55d0 100644
--- a/drivers/net/can/usb/Makefile
+++ b/drivers/net/can/usb/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_CAN_GS_USB) += gs_usb.o
 obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb.o
 obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
 obj-$(CONFIG_CAN_8DEV_USB) += usb_8dev.o
+obj-$(CONFIG_CAN_MCBA_USB) += mcba_usb.o
diff --git a/drivers/net/can/usb/mcba_usb.c b/drivers/net/can/usb/mcba_usb.c
new file mode 100644
index 000000000000..7f0272558bef
--- /dev/null
+++ b/drivers/net/can/usb/mcba_usb.c
@@ -0,0 +1,904 @@
+/* SocketCAN driver for Microchip CAN BUS Analyzer Tool
+ *
+ * Copyright (C) 2017 Mobica Limited
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.
+ *
+ * This driver is inspired by the 4.6.2 version of net/can/usb/usb_8dev.c
+ */
+
+#include <asm/unaligned.h>
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+#include <linux/can/led.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/signal.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+/* vendor and product id */
+#define MCBA_MODULE_NAME "mcba_usb"
+#define MCBA_VENDOR_ID 0x04d8
+#define MCBA_PRODUCT_ID 0x0a30
+
+/* driver constants */
+#define MCBA_MAX_RX_URBS 20
+#define MCBA_MAX_TX_URBS 20
+#define MCBA_CTX_FREE MCBA_MAX_TX_URBS
+
+/* RX buffer must be bigger than msg size since at the
+ * beggining USB messages are stacked.
+ */
+#define MCBA_USB_RX_BUFF_SIZE 64
+#define MCBA_USB_TX_BUFF_SIZE (sizeof(struct mcba_usb_msg))
+
+/* MCBA endpoint numbers */
+#define MCBA_USB_EP_IN 1
+#define MCBA_USB_EP_OUT 1
+
+/* Microchip command id */
+#define MBCA_CMD_RECEIVE_MESSAGE 0xE3
+#define MBCA_CMD_I_AM_ALIVE_FROM_CAN 0xF5
+#define MBCA_CMD_I_AM_ALIVE_FROM_USB 0xF7
+#define MBCA_CMD_CHANGE_BIT_RATE 0xA1
+#define MBCA_CMD_TRANSMIT_MESSAGE_EV 0xA3
+#define MBCA_CMD_SETUP_TERMINATION_RESISTANCE 0xA8
+#define MBCA_CMD_READ_FW_VERSION 0xA9
+#define MBCA_CMD_NOTHING_TO_SEND 0xFF
+#define MBCA_CMD_TRANSMIT_MESSAGE_RSP 0xE2
+
+#define MCBA_VER_REQ_USB 1
+#define MCBA_VER_REQ_CAN 2
+
+#define MCBA_SIDL_EXID_MASK 0x8
+#define MCBA_DLC_MASK 0xf
+#define MCBA_DLC_RTR_MASK 0x40
+
+#define MCBA_CAN_STATE_WRN_TH 95
+#define MCBA_CAN_STATE_ERR_PSV_TH 127
+
+#define MCBA_TERMINATION_DISABLED CAN_TERMINATION_DISABLED
+#define MCBA_TERMINATION_ENABLED 120
+
+struct mcba_usb_ctx {
+	struct mcba_priv *priv;
+	u32 ndx;
+	u8 dlc;
+	bool can;
+};
+
+/* Structure to hold all of our device specific stuff */
+struct mcba_priv {
+	struct can_priv can; /* must be the first member */
+	struct sk_buff *echo_skb[MCBA_MAX_TX_URBS];
+	struct mcba_usb_ctx tx_context[MCBA_MAX_TX_URBS];
+	struct usb_device *udev;
+	struct net_device *netdev;
+	struct usb_anchor tx_submitted;
+	struct usb_anchor rx_submitted;
+	struct can_berr_counter bec;
+	bool usb_ka_first_pass;
+	bool can_ka_first_pass;
+	bool can_speed_check;
+	atomic_t free_ctx_cnt;
+};
+
+/* CAN frame */
+struct __packed mcba_usb_msg_can {
+	u8 cmd_id;
+	__be16 eid;
+	__be16 sid;
+	u8 dlc;
+	u8 data[8];
+	u8 timestamp[4];
+	u8 checksum;
+};
+
+/* command frame */
+struct __packed mcba_usb_msg {
+	u8 cmd_id;
+	u8 unused[18];
+};
+
+struct __packed mcba_usb_msg_ka_usb {
+	u8 cmd_id;
+	u8 termination_state;
+	u8 soft_ver_major;
+	u8 soft_ver_minor;
+	u8 unused[15];
+};
+
+struct __packed mcba_usb_msg_ka_can {
+	u8 cmd_id;
+	u8 tx_err_cnt;
+	u8 rx_err_cnt;
+	u8 rx_buff_ovfl;
+	u8 tx_bus_off;
+	__be16 can_bitrate;
+	__le16 rx_lost;
+	u8 can_stat;
+	u8 soft_ver_major;
+	u8 soft_ver_minor;
+	u8 debug_mode;
+	u8 test_complete;
+	u8 test_result;
+	u8 unused[4];
+};
+
+struct __packed mcba_usb_msg_change_bitrate {
+	u8 cmd_id;
+	__be16 bitrate;
+	u8 unused[16];
+};
+
+struct __packed mcba_usb_msg_termination {
+	u8 cmd_id;
+	u8 termination;
+	u8 unused[17];
+};
+
+struct __packed mcba_usb_msg_fw_ver {
+	u8 cmd_id;
+	u8 pic;
+	u8 unused[17];
+};
+
+static const struct usb_device_id mcba_usb_table[] = {
+	{ USB_DEVICE(MCBA_VENDOR_ID, MCBA_PRODUCT_ID) },
+	{} /* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, mcba_usb_table);
+
+static const u16 mcba_termination[] = { MCBA_TERMINATION_DISABLED,
+					MCBA_TERMINATION_ENABLED };
+
+static const u32 mcba_bitrate[] = { 20000,  33333,  50000,  80000,  83333,
+				    100000, 125000, 150000, 175000, 200000,
+				    225000, 250000, 275000, 300000, 500000,
+				    625000, 800000, 1000000 };
+
+static inline void mcba_init_ctx(struct mcba_priv *priv)
+{
+	int i = 0;
+
+	for (i = 0; i < MCBA_MAX_TX_URBS; i++) {
+		priv->tx_context[i].ndx = MCBA_CTX_FREE;
+		priv->tx_context[i].priv = priv;
+	}
+
+	atomic_set(&priv->free_ctx_cnt, ARRAY_SIZE(priv->tx_context));
+}
+
+static inline struct mcba_usb_ctx *mcba_usb_get_free_ctx(struct mcba_priv *priv,
+							 struct can_frame *cf)
+{
+	int i = 0;
+	struct mcba_usb_ctx *ctx = NULL;
+
+	for (i = 0; i < MCBA_MAX_TX_URBS; i++) {
+		if (priv->tx_context[i].ndx == MCBA_CTX_FREE) {
+			ctx = &priv->tx_context[i];
+			ctx->ndx = i;
+
+			if (cf) {
+				ctx->can = true;
+				ctx->dlc = cf->can_dlc;
+			} else {
+				ctx->can = false;
+				ctx->dlc = 0;
+			}
+
+			atomic_dec(&priv->free_ctx_cnt);
+			break;
+		}
+	}
+
+	if (!atomic_read(&priv->free_ctx_cnt))
+		/* That was the last free ctx. Slow down tx path */
+		netif_stop_queue(priv->netdev);
+
+	return ctx;
+}
+
+/* mcba_usb_free_ctx and mcba_usb_get_free_ctx are executed by different
+ * threads. The order of execution in below function is important.
+ */
+static inline void mcba_usb_free_ctx(struct mcba_usb_ctx *ctx)
+{
+	/* Increase number of free ctxs before freeing ctx */
+	atomic_inc(&ctx->priv->free_ctx_cnt);
+
+	ctx->ndx = MCBA_CTX_FREE;
+
+	/* Wake up the queue once ctx is marked free */
+	netif_wake_queue(ctx->priv->netdev);
+}
+
+static void mcba_usb_write_bulk_callback(struct urb *urb)
+{
+	struct mcba_usb_ctx *ctx = urb->context;
+	struct net_device *netdev;
+
+	WARN_ON(!ctx);
+
+	netdev = ctx->priv->netdev;
+
+	/* free up our allocated buffer */
+	usb_free_coherent(urb->dev, urb->transfer_buffer_length,
+			  urb->transfer_buffer, urb->transfer_dma);
+
+	if (ctx->can) {
+		if (!netif_device_present(netdev))
+			return;
+
+		netdev->stats.tx_packets++;
+		netdev->stats.tx_bytes += ctx->dlc;
+
+		can_led_event(netdev, CAN_LED_EVENT_TX);
+		can_get_echo_skb(netdev, ctx->ndx);
+	}
+
+	if (urb->status)
+		netdev_info(netdev, "Tx URB aborted (%d)\n", urb->status);
+
+	/* Release the context */
+	mcba_usb_free_ctx(ctx);
+}
+
+/* Send data to device */
+static netdev_tx_t mcba_usb_xmit(struct mcba_priv *priv,
+				 struct mcba_usb_msg *usb_msg,
+				 struct mcba_usb_ctx *ctx)
+{
+	struct urb *urb;
+	u8 *buf;
+	int err;
+
+	/* create a URB, and a buffer for it, and copy the data to the URB */
+	urb = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!urb)
+		return -ENOMEM;
+
+	buf = usb_alloc_coherent(priv->udev, MCBA_USB_TX_BUFF_SIZE, GFP_ATOMIC,
+				 &urb->transfer_dma);
+	if (!buf) {
+		err = -ENOMEM;
+		goto nomembuf;
+	}
+
+	memcpy(buf, usb_msg, MCBA_USB_TX_BUFF_SIZE);
+
+	usb_fill_bulk_urb(urb, priv->udev,
+			  usb_sndbulkpipe(priv->udev, MCBA_USB_EP_OUT), buf,
+			  MCBA_USB_TX_BUFF_SIZE, mcba_usb_write_bulk_callback,
+			  ctx);
+
+	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+	usb_anchor_urb(urb, &priv->tx_submitted);
+
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+	if (unlikely(err))
+		goto failed;
+
+	/* Release our reference to this URB, the USB core will eventually free
+	 * it entirely.
+	 */
+	usb_free_urb(urb);
+
+	return 0;
+
+failed:
+	usb_unanchor_urb(urb);
+	usb_free_coherent(priv->udev, MCBA_USB_TX_BUFF_SIZE, buf,
+			  urb->transfer_dma);
+
+	if (err == -ENODEV)
+		netif_device_detach(priv->netdev);
+	else
+		netdev_warn(priv->netdev, "failed tx_urb %d\n", err);
+
+nomembuf:
+	usb_free_urb(urb);
+
+	return err;
+}
+
+/* Send data to device */
+static netdev_tx_t mcba_usb_start_xmit(struct sk_buff *skb,
+				       struct net_device *netdev)
+{
+	struct mcba_priv *priv = netdev_priv(netdev);
+	struct can_frame *cf = (struct can_frame *)skb->data;
+	struct mcba_usb_ctx *ctx = NULL;
+	struct net_device_stats *stats = &priv->netdev->stats;
+	u16 sid;
+	int err;
+	struct mcba_usb_msg_can usb_msg = {
+		.cmd_id = MBCA_CMD_TRANSMIT_MESSAGE_EV
+	};
+
+	if (can_dropped_invalid_skb(netdev, skb))
+		return NETDEV_TX_OK;
+
+	ctx = mcba_usb_get_free_ctx(priv, cf);
+	if (!ctx)
+		return NETDEV_TX_BUSY;
+
+	can_put_echo_skb(skb, priv->netdev, ctx->ndx);
+
+	if (cf->can_id & CAN_EFF_FLAG) {
+		/* SIDH    | SIDL                 | EIDH   | EIDL
+		 * 28 - 21 | 20 19 18 x x x 17 16 | 15 - 8 | 7 - 0
+		 */
+		sid = MCBA_SIDL_EXID_MASK;
+		/* store 28-18 bits */
+		sid |= (cf->can_id & 0x1ffc0000) >> 13;
+		/* store 17-16 bits */
+		sid |= (cf->can_id & 0x30000) >> 16;
+		put_unaligned_be16(sid, &usb_msg.sid);
+
+		/* store 15-0 bits */
+		put_unaligned_be16(cf->can_id & 0xffff, &usb_msg.eid);
+	} else {
+		/* SIDH   | SIDL
+		 * 10 - 3 | 2 1 0 x x x x x
+		 */
+		put_unaligned_be16((cf->can_id & CAN_SFF_MASK) << 5,
+				   &usb_msg.sid);
+		usb_msg.eid = 0;
+	}
+
+	usb_msg.dlc = cf->can_dlc;
+
+	memcpy(usb_msg.data, cf->data, usb_msg.dlc);
+
+	if (cf->can_id & CAN_RTR_FLAG)
+		usb_msg.dlc |= MCBA_DLC_RTR_MASK;
+
+	err = mcba_usb_xmit(priv, (struct mcba_usb_msg *)&usb_msg, ctx);
+	if (err)
+		goto xmit_failed;
+
+	return NETDEV_TX_OK;
+
+xmit_failed:
+	can_free_echo_skb(priv->netdev, ctx->ndx);
+	mcba_usb_free_ctx(ctx);
+	dev_kfree_skb(skb);
+	stats->tx_dropped++;
+
+	return NETDEV_TX_OK;
+}
+
+/* Send cmd to device */
+static void mcba_usb_xmit_cmd(struct mcba_priv *priv,
+			      struct mcba_usb_msg *usb_msg)
+{
+	struct mcba_usb_ctx *ctx = NULL;
+	int err;
+
+	ctx = mcba_usb_get_free_ctx(priv, NULL);
+	if (!ctx) {
+		netdev_err(priv->netdev,
+			   "Lack of free ctx. Sending (%d) cmd aborted",
+			   usb_msg->cmd_id);
+
+		return;
+	}
+
+	err = mcba_usb_xmit(priv, usb_msg, ctx);
+	if (err)
+		netdev_err(priv->netdev, "Failed to send cmd (%d)",
+			   usb_msg->cmd_id);
+}
+
+static void mcba_usb_xmit_change_bitrate(struct mcba_priv *priv, u16 bitrate)
+{
+	struct mcba_usb_msg_change_bitrate usb_msg = {
+		.cmd_id = MBCA_CMD_CHANGE_BIT_RATE
+	};
+
+	put_unaligned_be16(bitrate, &usb_msg.bitrate);
+
+	mcba_usb_xmit_cmd(priv, (struct mcba_usb_msg *)&usb_msg);
+}
+
+static void mcba_usb_xmit_read_fw_ver(struct mcba_priv *priv, u8 pic)
+{
+	struct mcba_usb_msg_fw_ver usb_msg = {
+		.cmd_id = MBCA_CMD_READ_FW_VERSION,
+		.pic = pic
+	};
+
+	mcba_usb_xmit_cmd(priv, (struct mcba_usb_msg *)&usb_msg);
+}
+
+static void mcba_usb_process_can(struct mcba_priv *priv,
+				 struct mcba_usb_msg_can *msg)
+{
+	struct can_frame *cf;
+	struct sk_buff *skb;
+	struct net_device_stats *stats = &priv->netdev->stats;
+	u16 sid;
+
+	skb = alloc_can_skb(priv->netdev, &cf);
+	if (!skb)
+		return;
+
+	sid = get_unaligned_be16(&msg->sid);
+
+	if (sid & MCBA_SIDL_EXID_MASK) {
+		/* SIDH    | SIDL                 | EIDH   | EIDL
+		 * 28 - 21 | 20 19 18 x x x 17 16 | 15 - 8 | 7 - 0
+		 */
+		cf->can_id = CAN_EFF_FLAG;
+
+		/* store 28-18 bits */
+		cf->can_id |= (sid & 0xffe0) << 13;
+		/* store 17-16 bits */
+		cf->can_id |= (sid & 3) << 16;
+		/* store 15-0 bits */
+		cf->can_id |= get_unaligned_be16(&msg->eid);
+	} else {
+		/* SIDH   | SIDL
+		 * 10 - 3 | 2 1 0 x x x x x
+		 */
+		cf->can_id = (sid & 0xffe0) >> 5;
+	}
+
+	if (msg->dlc & MCBA_DLC_RTR_MASK)
+		cf->can_id |= CAN_RTR_FLAG;
+
+	cf->can_dlc = get_can_dlc(msg->dlc & MCBA_DLC_MASK);
+
+	memcpy(cf->data, msg->data, cf->can_dlc);
+
+	stats->rx_packets++;
+	stats->rx_bytes += cf->can_dlc;
+
+	can_led_event(priv->netdev, CAN_LED_EVENT_RX);
+	netif_rx(skb);
+}
+
+static void mcba_usb_process_ka_usb(struct mcba_priv *priv,
+				    struct mcba_usb_msg_ka_usb *msg)
+{
+	if (unlikely(priv->usb_ka_first_pass)) {
+		netdev_info(priv->netdev, "PIC USB version %hhu.%hhu\n",
+			    msg->soft_ver_major, msg->soft_ver_minor);
+
+		priv->usb_ka_first_pass = false;
+	}
+
+	if (msg->termination_state)
+		priv->can.termination = MCBA_TERMINATION_ENABLED;
+	else
+		priv->can.termination = MCBA_TERMINATION_DISABLED;
+}
+
+static u32 convert_can2host_bitrate(struct mcba_usb_msg_ka_can *msg)
+{
+	const u32 bitrate = get_unaligned_be16(&msg->can_bitrate);
+
+	if ((bitrate == 33) || (bitrate == 83))
+		return bitrate * 1000 + 333;
+	else
+		return bitrate * 1000;
+}
+
+static void mcba_usb_process_ka_can(struct mcba_priv *priv,
+				    struct mcba_usb_msg_ka_can *msg)
+{
+	if (unlikely(priv->can_ka_first_pass)) {
+		netdev_info(priv->netdev, "PIC CAN version %hhu.%hhu\n",
+			    msg->soft_ver_major, msg->soft_ver_minor);
+
+		priv->can_ka_first_pass = false;
+	}
+
+	if (unlikely(priv->can_speed_check)) {
+		const u32 bitrate = convert_can2host_bitrate(msg);
+
+		priv->can_speed_check = false;
+
+		if (bitrate != priv->can.bittiming.bitrate)
+			netdev_err(
+			    priv->netdev,
+			    "Wrong bitrate reported by the device (%u). Expected %u",
+			    bitrate, priv->can.bittiming.bitrate);
+	}
+
+	priv->bec.txerr = msg->tx_err_cnt;
+	priv->bec.rxerr = msg->rx_err_cnt;
+
+	if (msg->tx_bus_off)
+		priv->can.state = CAN_STATE_BUS_OFF;
+
+	else if ((priv->bec.txerr > MCBA_CAN_STATE_ERR_PSV_TH) ||
+		 (priv->bec.rxerr > MCBA_CAN_STATE_ERR_PSV_TH))
+		priv->can.state = CAN_STATE_ERROR_PASSIVE;
+
+	else if ((priv->bec.txerr > MCBA_CAN_STATE_WRN_TH) ||
+		 (priv->bec.rxerr > MCBA_CAN_STATE_WRN_TH))
+		priv->can.state = CAN_STATE_ERROR_WARNING;
+}
+
+static void mcba_usb_process_rx(struct mcba_priv *priv,
+				struct mcba_usb_msg *msg)
+{
+	switch (msg->cmd_id) {
+	case MBCA_CMD_I_AM_ALIVE_FROM_CAN:
+		mcba_usb_process_ka_can(priv,
+					(struct mcba_usb_msg_ka_can *)msg);
+		break;
+
+	case MBCA_CMD_I_AM_ALIVE_FROM_USB:
+		mcba_usb_process_ka_usb(priv,
+					(struct mcba_usb_msg_ka_usb *)msg);
+		break;
+
+	case MBCA_CMD_RECEIVE_MESSAGE:
+		mcba_usb_process_can(priv, (struct mcba_usb_msg_can *)msg);
+		break;
+
+	case MBCA_CMD_NOTHING_TO_SEND:
+		/* Side effect of communication between PIC_USB and PIC_CAN.
+		 * PIC_CAN is telling us that it has nothing to send
+		 */
+		break;
+
+	case MBCA_CMD_TRANSMIT_MESSAGE_RSP:
+		/* Transmission response from the device containing timestamp */
+		break;
+
+	default:
+		netdev_warn(priv->netdev, "Unsupported msg (0x%hhX)",
+			    msg->cmd_id);
+		break;
+	}
+}
+
+/* Callback for reading data from device
+ *
+ * Check urb status, call read function and resubmit urb read operation.
+ */
+static void mcba_usb_read_bulk_callback(struct urb *urb)
+{
+	struct mcba_priv *priv = urb->context;
+	struct net_device *netdev;
+	int retval;
+	int pos = 0;
+
+	netdev = priv->netdev;
+
+	if (!netif_device_present(netdev))
+		return;
+
+	switch (urb->status) {
+	case 0: /* success */
+		break;
+
+	case -ENOENT:
+	case -ESHUTDOWN:
+		return;
+
+	default:
+		netdev_info(netdev, "Rx URB aborted (%d)\n", urb->status);
+
+		goto resubmit_urb;
+	}
+
+	while (pos < urb->actual_length) {
+		struct mcba_usb_msg *msg;
+
+		if (pos + sizeof(struct mcba_usb_msg) > urb->actual_length) {
+			netdev_err(priv->netdev, "format error\n");
+			break;
+		}
+
+		msg = (struct mcba_usb_msg *)(urb->transfer_buffer + pos);
+		mcba_usb_process_rx(priv, msg);
+
+		pos += sizeof(struct mcba_usb_msg);
+	}
+
+resubmit_urb:
+
+	usb_fill_bulk_urb(urb, priv->udev,
+			  usb_rcvbulkpipe(priv->udev, MCBA_USB_EP_OUT),
+			  urb->transfer_buffer, MCBA_USB_RX_BUFF_SIZE,
+			  mcba_usb_read_bulk_callback, priv);
+
+	retval = usb_submit_urb(urb, GFP_ATOMIC);
+
+	if (retval == -ENODEV)
+		netif_device_detach(netdev);
+	else if (retval)
+		netdev_err(netdev, "failed resubmitting read bulk urb: %d\n",
+			   retval);
+}
+
+/* Start USB device */
+static int mcba_usb_start(struct mcba_priv *priv)
+{
+	struct net_device *netdev = priv->netdev;
+	int err, i;
+
+	mcba_init_ctx(priv);
+
+	for (i = 0; i < MCBA_MAX_RX_URBS; i++) {
+		struct urb *urb = NULL;
+		u8 *buf;
+
+		/* create a URB, and a buffer for it */
+		urb = usb_alloc_urb(0, GFP_KERNEL);
+		if (!urb) {
+			err = -ENOMEM;
+			break;
+		}
+
+		buf = usb_alloc_coherent(priv->udev, MCBA_USB_RX_BUFF_SIZE,
+					 GFP_KERNEL, &urb->transfer_dma);
+		if (!buf) {
+			netdev_err(netdev, "No memory left for USB buffer\n");
+			usb_free_urb(urb);
+			err = -ENOMEM;
+			break;
+		}
+
+		usb_fill_bulk_urb(urb, priv->udev,
+				  usb_rcvbulkpipe(priv->udev, MCBA_USB_EP_IN),
+				  buf, MCBA_USB_RX_BUFF_SIZE,
+				  mcba_usb_read_bulk_callback, priv);
+		urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+		usb_anchor_urb(urb, &priv->rx_submitted);
+
+		err = usb_submit_urb(urb, GFP_KERNEL);
+		if (err) {
+			usb_unanchor_urb(urb);
+			usb_free_coherent(priv->udev, MCBA_USB_RX_BUFF_SIZE,
+					  buf, urb->transfer_dma);
+			usb_free_urb(urb);
+			break;
+		}
+
+		/* Drop reference, USB core will take care of freeing it */
+		usb_free_urb(urb);
+	}
+
+	/* Did we submit any URBs */
+	if (i == 0) {
+		netdev_warn(netdev, "couldn't setup read URBs\n");
+		return err;
+	}
+
+	/* Warn if we've couldn't transmit all the URBs */
+	if (i < MCBA_MAX_RX_URBS)
+		netdev_warn(netdev, "rx performance may be slow\n");
+
+	mcba_usb_xmit_read_fw_ver(priv, MCBA_VER_REQ_USB);
+	mcba_usb_xmit_read_fw_ver(priv, MCBA_VER_REQ_CAN);
+
+	return err;
+}
+
+/* Open USB device */
+static int mcba_usb_open(struct net_device *netdev)
+{
+	struct mcba_priv *priv = netdev_priv(netdev);
+	int err;
+
+	/* common open */
+	err = open_candev(netdev);
+	if (err)
+		return err;
+
+	priv->can_speed_check = true;
+	priv->can.state = CAN_STATE_ERROR_ACTIVE;
+
+	can_led_event(netdev, CAN_LED_EVENT_OPEN);
+	netif_start_queue(netdev);
+
+	return 0;
+}
+
+static void mcba_urb_unlink(struct mcba_priv *priv)
+{
+	usb_kill_anchored_urbs(&priv->rx_submitted);
+	usb_kill_anchored_urbs(&priv->tx_submitted);
+}
+
+/* Close USB device */
+static int mcba_usb_close(struct net_device *netdev)
+{
+	struct mcba_priv *priv = netdev_priv(netdev);
+
+	priv->can.state = CAN_STATE_STOPPED;
+
+	netif_stop_queue(netdev);
+
+	/* Stop polling */
+	mcba_urb_unlink(priv);
+
+	close_candev(netdev);
+	can_led_event(netdev, CAN_LED_EVENT_STOP);
+
+	return 0;
+}
+
+/* Set network device mode
+ *
+ * Maybe we should leave this function empty, because the device
+ * set mode variable with open command.
+ */
+static int mcba_net_set_mode(struct net_device *netdev, enum can_mode mode)
+{
+	return 0;
+}
+
+static int mcba_net_get_berr_counter(const struct net_device *netdev,
+				     struct can_berr_counter *bec)
+{
+	struct mcba_priv *priv = netdev_priv(netdev);
+
+	bec->txerr = priv->bec.txerr;
+	bec->rxerr = priv->bec.rxerr;
+
+	return 0;
+}
+
+static const struct net_device_ops mcba_netdev_ops = {
+	.ndo_open = mcba_usb_open,
+	.ndo_stop = mcba_usb_close,
+	.ndo_start_xmit = mcba_usb_start_xmit,
+};
+
+/* Microchip CANBUS has hardcoded bittiming values by default.
+ * This function sends request via USB to change the speed and align bittiming
+ * values for presentation purposes only
+ */
+static int mcba_net_set_bittiming(struct net_device *netdev)
+{
+	struct mcba_priv *priv = netdev_priv(netdev);
+	const u16 bitrate_kbps = priv->can.bittiming.bitrate / 1000;
+
+	mcba_usb_xmit_change_bitrate(priv, bitrate_kbps);
+
+	return 0;
+}
+
+static int mcba_set_termination(struct net_device *netdev, u16 term)
+{
+	struct mcba_priv *priv = netdev_priv(netdev);
+	struct mcba_usb_msg_termination usb_msg = {
+		.cmd_id = MBCA_CMD_SETUP_TERMINATION_RESISTANCE
+	};
+
+	if (term == MCBA_TERMINATION_ENABLED)
+		usb_msg.termination = 1;
+	else
+		usb_msg.termination = 0;
+
+	mcba_usb_xmit_cmd(priv, (struct mcba_usb_msg *)&usb_msg);
+
+	return 0;
+}
+
+static int mcba_usb_probe(struct usb_interface *intf,
+			  const struct usb_device_id *id)
+{
+	struct net_device *netdev;
+	struct mcba_priv *priv;
+	int err = -ENOMEM;
+	struct usb_device *usbdev = interface_to_usbdev(intf);
+
+	netdev = alloc_candev(sizeof(struct mcba_priv), MCBA_MAX_TX_URBS);
+	if (!netdev) {
+		dev_err(&intf->dev, "Couldn't alloc candev\n");
+		return -ENOMEM;
+	}
+
+	priv = netdev_priv(netdev);
+
+	priv->udev = usbdev;
+	priv->netdev = netdev;
+	priv->usb_ka_first_pass = true;
+	priv->can_ka_first_pass = true;
+	priv->can_speed_check = false;
+
+	init_usb_anchor(&priv->rx_submitted);
+	init_usb_anchor(&priv->tx_submitted);
+
+	usb_set_intfdata(intf, priv);
+
+	/* Init CAN device */
+	priv->can.state = CAN_STATE_STOPPED;
+	priv->can.termination_const = mcba_termination;
+	priv->can.termination_const_cnt = ARRAY_SIZE(mcba_termination);
+	priv->can.bitrate_const = mcba_bitrate;
+	priv->can.bitrate_const_cnt = ARRAY_SIZE(mcba_bitrate);
+
+	priv->can.do_set_termination = mcba_set_termination;
+	priv->can.do_set_mode = mcba_net_set_mode;
+	priv->can.do_get_berr_counter = mcba_net_get_berr_counter;
+	priv->can.do_set_bittiming = mcba_net_set_bittiming;
+
+	netdev->netdev_ops = &mcba_netdev_ops;
+
+	netdev->flags |= IFF_ECHO; /* we support local echo */
+
+	SET_NETDEV_DEV(netdev, &intf->dev);
+
+	err = register_candev(netdev);
+	if (err) {
+		netdev_err(netdev, "couldn't register CAN device: %d\n", err);
+
+		goto cleanup_free_candev;
+	}
+
+	devm_can_led_init(netdev);
+
+	/* Start USB dev only if we have successfully registered CAN device */
+	err = mcba_usb_start(priv);
+	if (err) {
+		if (err == -ENODEV)
+			netif_device_detach(priv->netdev);
+
+		netdev_warn(netdev, "couldn't start device: %d\n", err);
+
+		goto cleanup_unregister_candev;
+	}
+
+	dev_info(&intf->dev, "Microchip CAN BUS analizer connected\n");
+
+	return 0;
+
+cleanup_unregister_candev:
+	unregister_candev(priv->netdev);
+
+cleanup_free_candev:
+	free_candev(netdev);
+
+	return err;
+}
+
+/* Called by the usb core when driver is unloaded or device is removed */
+static void mcba_usb_disconnect(struct usb_interface *intf)
+{
+	struct mcba_priv *priv = usb_get_intfdata(intf);
+
+	usb_set_intfdata(intf, NULL);
+
+	netdev_info(priv->netdev, "device disconnected\n");
+
+	unregister_candev(priv->netdev);
+	free_candev(priv->netdev);
+
+	mcba_urb_unlink(priv);
+}
+
+static struct usb_driver mcba_usb_driver = {
+	.name = MCBA_MODULE_NAME,
+	.probe = mcba_usb_probe,
+	.disconnect = mcba_usb_disconnect,
+	.id_table = mcba_usb_table,
+};
+
+module_usb_driver(mcba_usb_driver);
+
+MODULE_AUTHOR("Remigiusz Kołłątaj <remigiusz.kollataj@mobica.com>");
+MODULE_DESCRIPTION("SocketCAN driver for Microchip CAN BUS Analyzer Tool");
+MODULE_LICENSE("GPL v2");