--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/* Fintek F81604 USB-to-2CAN controller driver.
+ *
+ * Copyright (C) 2023 Ji-Ze Hong (Peter Hong) <peter_hong@fintek.com.tw>
+ */
+#include <linux/bitfield.h>
+#include <linux/netdevice.h>
+#include <linux/units.h>
+#include <linux/usb.h>
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+#include <linux/can/platform/sja1000.h>
+
+#include <asm-generic/unaligned.h>
+
+/* vendor and product id */
+#define F81604_VENDOR_ID 0x2c42
+#define F81604_PRODUCT_ID 0x1709
+#define F81604_CAN_CLOCK (12 * MEGA)
+#define F81604_MAX_DEV 2
+#define F81604_SET_DEVICE_RETRY 10
+
+#define F81604_USB_TIMEOUT 2000
+#define F81604_SET_GET_REGISTER 0xA0
+#define F81604_PORT_OFFSET 0x1000
+#define F81604_MAX_RX_URBS 4
+
+#define F81604_CMD_DATA 0x00
+
+#define F81604_DLC_LEN_MASK GENMASK(3, 0)
+#define F81604_DLC_EFF_BIT BIT(7)
+#define F81604_DLC_RTR_BIT BIT(6)
+
+#define F81604_SFF_SHIFT 5
+#define F81604_EFF_SHIFT 3
+
+#define F81604_BRP_MASK GENMASK(5, 0)
+#define F81604_SJW_MASK GENMASK(7, 6)
+
+#define F81604_SEG1_MASK GENMASK(3, 0)
+#define F81604_SEG2_MASK GENMASK(6, 4)
+
+#define F81604_CLEAR_ALC 0
+#define F81604_CLEAR_ECC 1
+#define F81604_CLEAR_OVERRUN 2
+
+/* device setting */
+#define F81604_CTRL_MODE_REG 0x80
+#define F81604_TX_ONESHOT (0x03 << 3)
+#define F81604_TX_NORMAL (0x01 << 3)
+#define F81604_RX_AUTO_RELEASE_BUF BIT(1)
+#define F81604_INT_WHEN_CHANGE BIT(0)
+
+#define F81604_TERMINATOR_REG 0x105
+#define F81604_CAN0_TERM BIT(2)
+#define F81604_CAN1_TERM BIT(3)
+
+#define F81604_TERMINATION_DISABLED CAN_TERMINATION_DISABLED
+#define F81604_TERMINATION_ENABLED 120
+
+/* SJA1000 registers - manual section 6.4 (Pelican Mode) */
+#define F81604_SJA1000_MOD 0x00
+#define F81604_SJA1000_CMR 0x01
+#define F81604_SJA1000_IR 0x03
+#define F81604_SJA1000_IER 0x04
+#define F81604_SJA1000_ALC 0x0B
+#define F81604_SJA1000_ECC 0x0C
+#define F81604_SJA1000_RXERR 0x0E
+#define F81604_SJA1000_TXERR 0x0F
+#define F81604_SJA1000_ACCC0 0x10
+#define F81604_SJA1000_ACCM0 0x14
+#define F81604_MAX_FILTER_CNT 4
+
+/* Common registers - manual section 6.5 */
+#define F81604_SJA1000_BTR0 0x06
+#define F81604_SJA1000_BTR1 0x07
+#define F81604_SJA1000_BTR1_SAMPLE_TRIPLE BIT(7)
+#define F81604_SJA1000_OCR 0x08
+#define F81604_SJA1000_CDR 0x1F
+
+/* mode register */
+#define F81604_SJA1000_MOD_RM 0x01
+#define F81604_SJA1000_MOD_LOM 0x02
+#define F81604_SJA1000_MOD_STM 0x04
+
+/* commands */
+#define F81604_SJA1000_CMD_CDO 0x08
+
+/* interrupt sources */
+#define F81604_SJA1000_IRQ_BEI 0x80
+#define F81604_SJA1000_IRQ_ALI 0x40
+#define F81604_SJA1000_IRQ_EPI 0x20
+#define F81604_SJA1000_IRQ_DOI 0x08
+#define F81604_SJA1000_IRQ_EI 0x04
+#define F81604_SJA1000_IRQ_TI 0x02
+#define F81604_SJA1000_IRQ_RI 0x01
+#define F81604_SJA1000_IRQ_ALL 0xFF
+#define F81604_SJA1000_IRQ_OFF 0x00
+
+/* status register content */
+#define F81604_SJA1000_SR_BS 0x80
+#define F81604_SJA1000_SR_ES 0x40
+#define F81604_SJA1000_SR_TCS 0x08
+
+/* ECC register */
+#define F81604_SJA1000_ECC_SEG 0x1F
+#define F81604_SJA1000_ECC_DIR 0x20
+#define F81604_SJA1000_ECC_BIT 0x00
+#define F81604_SJA1000_ECC_FORM 0x40
+#define F81604_SJA1000_ECC_STUFF 0x80
+#define F81604_SJA1000_ECC_MASK 0xc0
+
+/* ALC register */
+#define F81604_SJA1000_ALC_MASK 0x1f
+
+/* table of devices that work with this driver */
+static const struct usb_device_id f81604_table[] = {
+       { USB_DEVICE(F81604_VENDOR_ID, F81604_PRODUCT_ID) },
+       {} /* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, f81604_table);
+
+static const struct ethtool_ops f81604_ethtool_ops = {
+       .get_ts_info = ethtool_op_get_ts_info,
+};
+
+static const u16 f81604_termination[] = { F81604_TERMINATION_DISABLED,
+                                         F81604_TERMINATION_ENABLED };
+
+struct f81604_priv {
+       struct net_device *netdev[F81604_MAX_DEV];
+};
+
+struct f81604_port_priv {
+       struct can_priv can;
+       struct net_device *netdev;
+       struct sk_buff *echo_skb;
+
+       unsigned long clear_flags;
+       struct work_struct clear_reg_work;
+
+       struct usb_device *dev;
+       struct usb_interface *intf;
+
+       struct usb_anchor urbs_anchor;
+};
+
+/* Interrupt endpoint data format:
+ *     Byte 0: Status register.
+ *     Byte 1: Interrupt register.
+ *     Byte 2: Interrupt enable register.
+ *     Byte 3: Arbitration lost capture(ALC) register.
+ *     Byte 4: Error code capture(ECC) register.
+ *     Byte 5: Error warning limit register.
+ *     Byte 6: RX error counter register.
+ *     Byte 7: TX error counter register.
+ *     Byte 8: Reserved.
+ */
+struct f81604_int_data {
+       u8 sr;
+       u8 isrc;
+       u8 ier;
+       u8 alc;
+       u8 ecc;
+       u8 ewlr;
+       u8 rxerr;
+       u8 txerr;
+       u8 val;
+} __packed __aligned(4);
+
+struct f81604_sff {
+       __be16 id;
+       u8 data[CAN_MAX_DLEN];
+} __packed __aligned(2);
+
+struct f81604_eff {
+       __be32 id;
+       u8 data[CAN_MAX_DLEN];
+} __packed __aligned(2);
+
+struct f81604_can_frame {
+       u8 cmd;
+
+       /* According for F81604 DLC define:
+        *      bit 3~0: data length (0~8)
+        *      bit6: is RTR flag.
+        *      bit7: is EFF frame.
+        */
+       u8 dlc;
+
+       union {
+               struct f81604_sff sff;
+               struct f81604_eff eff;
+       };
+} __packed __aligned(2);
+
+static const u8 bulk_in_addr[F81604_MAX_DEV] = { 2, 4 };
+static const u8 bulk_out_addr[F81604_MAX_DEV] = { 1, 3 };
+static const u8 int_in_addr[F81604_MAX_DEV] = { 1, 3 };
+
+static int f81604_write(struct usb_device *dev, u16 reg, u8 data)
+{
+       int ret;
+
+       ret = usb_control_msg_send(dev, 0, F81604_SET_GET_REGISTER,
+                                  USB_TYPE_VENDOR | USB_DIR_OUT, 0, reg,
+                                  &data, sizeof(data), F81604_USB_TIMEOUT,
+                                  GFP_KERNEL);
+       if (ret)
+               dev_err(&dev->dev, "%s: reg: %x data: %x failed: %pe\n",
+                       __func__, reg, data, ERR_PTR(ret));
+
+       return ret;
+}
+
+static int f81604_read(struct usb_device *dev, u16 reg, u8 *data)
+{
+       int ret;
+
+       ret = usb_control_msg_recv(dev, 0, F81604_SET_GET_REGISTER,
+                                  USB_TYPE_VENDOR | USB_DIR_IN, 0, reg, data,
+                                  sizeof(*data), F81604_USB_TIMEOUT,
+                                  GFP_KERNEL);
+
+       if (ret < 0)
+               dev_err(&dev->dev, "%s: reg: %x failed: %pe\n", __func__, reg,
+                       ERR_PTR(ret));
+
+       return ret;
+}
+
+static int f81604_update_bits(struct usb_device *dev, u16 reg, u8 mask,
+                             u8 data)
+{
+       int ret;
+       u8 tmp;
+
+       ret = f81604_read(dev, reg, &tmp);
+       if (ret)
+               return ret;
+
+       tmp &= ~mask;
+       tmp |= (mask & data);
+
+       return f81604_write(dev, reg, tmp);
+}
+
+static int f81604_sja1000_write(struct f81604_port_priv *priv, u16 reg,
+                               u8 data)
+{
+       int port = priv->netdev->dev_port;
+       int real_reg;
+
+       real_reg = reg + F81604_PORT_OFFSET * port + F81604_PORT_OFFSET;
+       return f81604_write(priv->dev, real_reg, data);
+}
+
+static int f81604_sja1000_read(struct f81604_port_priv *priv, u16 reg,
+                              u8 *data)
+{
+       int port = priv->netdev->dev_port;
+       int real_reg;
+
+       real_reg = reg + F81604_PORT_OFFSET * port + F81604_PORT_OFFSET;
+       return f81604_read(priv->dev, real_reg, data);
+}
+
+static int f81604_set_reset_mode(struct f81604_port_priv *priv)
+{
+       int ret, i;
+       u8 tmp;
+
+       /* disable interrupts */
+       ret = f81604_sja1000_write(priv, F81604_SJA1000_IER,
+                                  F81604_SJA1000_IRQ_OFF);
+       if (ret)
+               return ret;
+
+       for (i = 0; i < F81604_SET_DEVICE_RETRY; i++) {
+               ret = f81604_sja1000_read(priv, F81604_SJA1000_MOD, &tmp);
+               if (ret)
+                       return ret;
+
+               /* check reset bit */
+               if (tmp & F81604_SJA1000_MOD_RM) {
+                       priv->can.state = CAN_STATE_STOPPED;
+                       return 0;
+               }
+
+               /* reset chip */
+               ret = f81604_sja1000_write(priv, F81604_SJA1000_MOD,
+                                          F81604_SJA1000_MOD_RM);
+               if (ret)
+                       return ret;
+       }
+
+       return -EPERM;
+}
+
+static int f81604_set_normal_mode(struct f81604_port_priv *priv)
+{
+       u8 tmp, ier = 0;
+       u8 mod_reg = 0;
+       int ret, i;
+
+       for (i = 0; i < F81604_SET_DEVICE_RETRY; i++) {
+               ret = f81604_sja1000_read(priv, F81604_SJA1000_MOD, &tmp);
+               if (ret)
+                       return ret;
+
+               /* check reset bit */
+               if ((tmp & F81604_SJA1000_MOD_RM) == 0) {
+                       priv->can.state = CAN_STATE_ERROR_ACTIVE;
+                       /* enable interrupts, RI handled by bulk-in */
+                       ier = F81604_SJA1000_IRQ_ALL & ~F81604_SJA1000_IRQ_RI;
+                       if (!(priv->can.ctrlmode &
+                             CAN_CTRLMODE_BERR_REPORTING))
+                               ier &= ~F81604_SJA1000_IRQ_BEI;
+
+                       return f81604_sja1000_write(priv, F81604_SJA1000_IER,
+                                                   ier);
+               }
+
+               /* set chip to normal mode */
+               if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
+                       mod_reg |= F81604_SJA1000_MOD_LOM;
+               if (priv->can.ctrlmode & CAN_CTRLMODE_PRESUME_ACK)
+                       mod_reg |= F81604_SJA1000_MOD_STM;
+
+               ret = f81604_sja1000_write(priv, F81604_SJA1000_MOD, mod_reg);
+               if (ret)
+                       return ret;
+       }
+
+       return -EPERM;
+}
+
+static int f81604_chipset_init(struct f81604_port_priv *priv)
+{
+       int i, ret;
+
+       /* set clock divider and output control register */
+       ret = f81604_sja1000_write(priv, F81604_SJA1000_CDR,
+                                  CDR_CBP | CDR_PELICAN);
+       if (ret)
+               return ret;
+
+       /* set acceptance filter (accept all) */
+       for (i = 0; i < F81604_MAX_FILTER_CNT; ++i) {
+               ret = f81604_sja1000_write(priv, F81604_SJA1000_ACCC0 + i, 0);
+               if (ret)
+                       return ret;
+       }
+
+       for (i = 0; i < F81604_MAX_FILTER_CNT; ++i) {
+               ret = f81604_sja1000_write(priv, F81604_SJA1000_ACCM0 + i,
+                                          0xFF);
+               if (ret)
+                       return ret;
+       }
+
+       return f81604_sja1000_write(priv, F81604_SJA1000_OCR,
+                                   OCR_TX0_PUSHPULL | OCR_TX1_PUSHPULL |
+                                           OCR_MODE_NORMAL);
+}
+
+static void f81604_process_rx_packet(struct net_device *netdev,
+                                    struct f81604_can_frame *frame)
+{
+       struct net_device_stats *stats = &netdev->stats;
+       struct can_frame *cf;
+       struct sk_buff *skb;
+
+       if (frame->cmd != F81604_CMD_DATA)
+               return;
+
+       skb = alloc_can_skb(netdev, &cf);
+       if (!skb) {
+               stats->rx_dropped++;
+               return;
+       }
+
+       cf->len = can_cc_dlc2len(frame->dlc & F81604_DLC_LEN_MASK);
+
+       if (frame->dlc & F81604_DLC_EFF_BIT) {
+               cf->can_id = get_unaligned_be32(&frame->eff.id) >>
+                            F81604_EFF_SHIFT;
+               cf->can_id |= CAN_EFF_FLAG;
+
+               if (!(frame->dlc & F81604_DLC_RTR_BIT))
+                       memcpy(cf->data, frame->eff.data, cf->len);
+       } else {
+               cf->can_id = get_unaligned_be16(&frame->sff.id) >>
+                            F81604_SFF_SHIFT;
+
+               if (!(frame->dlc & F81604_DLC_RTR_BIT))
+                       memcpy(cf->data, frame->sff.data, cf->len);
+       }
+
+       if (frame->dlc & F81604_DLC_RTR_BIT)
+               cf->can_id |= CAN_RTR_FLAG;
+       else
+               stats->rx_bytes += cf->len;
+
+       stats->rx_packets++;
+       netif_rx(skb);
+}
+
+static void f81604_read_bulk_callback(struct urb *urb)
+{
+       struct f81604_can_frame *frame = urb->transfer_buffer;
+       struct net_device *netdev = urb->context;
+       int ret;
+
+       if (!netif_device_present(netdev))
+               return;
+
+       if (urb->status)
+               netdev_info(netdev, "%s: URB aborted %pe\n", __func__,
+                           ERR_PTR(urb->status));
+
+       switch (urb->status) {
+       case 0: /* success */
+               break;
+
+       case -ENOENT:
+       case -EPIPE:
+       case -EPROTO:
+       case -ESHUTDOWN:
+               return;
+
+       default:
+               goto resubmit_urb;
+       }
+
+       if (urb->actual_length != sizeof(*frame)) {
+               netdev_warn(netdev, "URB length %u not equal to %zu\n",
+                           urb->actual_length, sizeof(*frame));
+               goto resubmit_urb;
+       }
+
+       f81604_process_rx_packet(netdev, frame);
+
+resubmit_urb:
+       ret = usb_submit_urb(urb, GFP_ATOMIC);
+       if (ret == -ENODEV)
+               netif_device_detach(netdev);
+       else if (ret)
+               netdev_err(netdev,
+                          "%s: failed to resubmit read bulk urb: %pe\n",
+                          __func__, ERR_PTR(ret));
+}
+
+static void f81604_handle_tx(struct f81604_port_priv *priv,
+                            struct f81604_int_data *data)
+{
+       struct net_device *netdev = priv->netdev;
+       struct net_device_stats *stats = &netdev->stats;
+
+       /* transmission buffer released */
+       if (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT &&
+           !(data->sr & F81604_SJA1000_SR_TCS)) {
+               stats->tx_errors++;
+               can_free_echo_skb(netdev, 0, NULL);
+       } else {
+               /* transmission complete */
+               stats->tx_bytes += can_get_echo_skb(netdev, 0, NULL);
+               stats->tx_packets++;
+       }
+
+       netif_wake_queue(netdev);
+}
+
+static void f81604_handle_can_bus_errors(struct f81604_port_priv *priv,
+                                        struct f81604_int_data *data)
+{
+       enum can_state can_state = priv->can.state;
+       struct net_device *netdev = priv->netdev;
+       struct net_device_stats *stats = &netdev->stats;
+       struct can_frame *cf;
+       struct sk_buff *skb;
+
+       /* Note: ALC/ECC will not auto clear by read here, must be cleared by
+        * read register (via clear_reg_work).
+        */
+
+       skb = alloc_can_err_skb(netdev, &cf);
+       if (skb) {
+               cf->can_id |= CAN_ERR_CNT;
+               cf->data[6] = data->txerr;
+               cf->data[7] = data->rxerr;
+       }
+
+       if (data->isrc & F81604_SJA1000_IRQ_DOI) {
+               /* data overrun interrupt */
+               netdev_dbg(netdev, "data overrun interrupt\n");
+
+               if (skb) {
+                       cf->can_id |= CAN_ERR_CRTL;
+                       cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+               }
+
+               stats->rx_over_errors++;
+               stats->rx_errors++;
+
+               set_bit(F81604_CLEAR_OVERRUN, &priv->clear_flags);
+       }
+
+       if (data->isrc & F81604_SJA1000_IRQ_EI) {
+               /* error warning interrupt */
+               netdev_dbg(netdev, "error warning interrupt\n");
+
+               if (data->sr & F81604_SJA1000_SR_BS)
+                       can_state = CAN_STATE_BUS_OFF;
+               else if (data->sr & F81604_SJA1000_SR_ES)
+                       can_state = CAN_STATE_ERROR_WARNING;
+               else
+                       can_state = CAN_STATE_ERROR_ACTIVE;
+       }
+
+       if (data->isrc & F81604_SJA1000_IRQ_BEI) {
+               /* bus error interrupt */
+               netdev_dbg(netdev, "bus error interrupt\n");
+
+               priv->can.can_stats.bus_error++;
+               stats->rx_errors++;
+
+               if (skb) {
+                       cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
+
+                       /* set error type */
+                       switch (data->ecc & F81604_SJA1000_ECC_MASK) {
+                       case F81604_SJA1000_ECC_BIT:
+                               cf->data[2] |= CAN_ERR_PROT_BIT;
+                               break;
+                       case F81604_SJA1000_ECC_FORM:
+                               cf->data[2] |= CAN_ERR_PROT_FORM;
+                               break;
+                       case F81604_SJA1000_ECC_STUFF:
+                               cf->data[2] |= CAN_ERR_PROT_STUFF;
+                               break;
+                       default:
+                               break;
+                       }
+
+                       /* set error location */
+                       cf->data[3] = data->ecc & F81604_SJA1000_ECC_SEG;
+
+                       /* Error occurred during transmission? */
+                       if ((data->ecc & F81604_SJA1000_ECC_DIR) == 0)
+                               cf->data[2] |= CAN_ERR_PROT_TX;
+               }
+
+               set_bit(F81604_CLEAR_ECC, &priv->clear_flags);
+       }
+
+       if (data->isrc & F81604_SJA1000_IRQ_EPI) {
+               if (can_state == CAN_STATE_ERROR_PASSIVE)
+                       can_state = CAN_STATE_ERROR_WARNING;
+               else
+                       can_state = CAN_STATE_ERROR_PASSIVE;
+
+               /* error passive interrupt */
+               netdev_dbg(netdev, "error passive interrupt: %d\n", can_state);
+       }
+
+       if (data->isrc & F81604_SJA1000_IRQ_ALI) {
+               /* arbitration lost interrupt */
+               netdev_dbg(netdev, "arbitration lost interrupt\n");
+
+               priv->can.can_stats.arbitration_lost++;
+
+               if (skb) {
+                       cf->can_id |= CAN_ERR_LOSTARB;
+                       cf->data[0] = data->alc & F81604_SJA1000_ALC_MASK;
+               }
+
+               set_bit(F81604_CLEAR_ALC, &priv->clear_flags);
+       }
+
+       if (can_state != priv->can.state) {
+               enum can_state tx_state, rx_state;
+
+               tx_state = data->txerr >= data->rxerr ? can_state : 0;
+               rx_state = data->txerr <= data->rxerr ? can_state : 0;
+
+               can_change_state(netdev, cf, tx_state, rx_state);
+
+               if (can_state == CAN_STATE_BUS_OFF)
+                       can_bus_off(netdev);
+       }
+
+       if (priv->clear_flags)
+               schedule_work(&priv->clear_reg_work);
+
+       if (skb)
+               netif_rx(skb);
+}
+
+static void f81604_read_int_callback(struct urb *urb)
+{
+       struct f81604_int_data *data = urb->transfer_buffer;
+       struct net_device *netdev = urb->context;
+       struct f81604_port_priv *priv;
+       int ret;
+
+       priv = netdev_priv(netdev);
+
+       if (!netif_device_present(netdev))
+               return;
+
+       if (urb->status)
+               netdev_info(netdev, "%s: Int URB aborted: %pe\n", __func__,
+                           ERR_PTR(urb->status));
+
+       switch (urb->status) {
+       case 0: /* success */
+               break;
+
+       case -ENOENT:
+       case -EPIPE:
+       case -EPROTO:
+       case -ESHUTDOWN:
+               return;
+
+       default:
+               goto resubmit_urb;
+       }
+
+       /* handle Errors */
+       if (data->isrc & (F81604_SJA1000_IRQ_DOI | F81604_SJA1000_IRQ_EI |
+                         F81604_SJA1000_IRQ_BEI | F81604_SJA1000_IRQ_EPI |
+                         F81604_SJA1000_IRQ_ALI))
+               f81604_handle_can_bus_errors(priv, data);
+
+       /* handle TX */
+       if (priv->can.state != CAN_STATE_BUS_OFF &&
+           (data->isrc & F81604_SJA1000_IRQ_TI))
+               f81604_handle_tx(priv, data);
+
+resubmit_urb:
+       ret = usb_submit_urb(urb, GFP_ATOMIC);
+       if (ret == -ENODEV)
+               netif_device_detach(netdev);
+       else if (ret)
+               netdev_err(netdev, "%s: failed to resubmit int urb: %pe\n",
+                          __func__, ERR_PTR(ret));
+}
+
+static void f81604_unregister_urbs(struct f81604_port_priv *priv)
+{
+       usb_kill_anchored_urbs(&priv->urbs_anchor);
+}
+
+static int f81604_register_urbs(struct f81604_port_priv *priv)
+{
+       struct net_device *netdev = priv->netdev;
+       struct f81604_int_data *int_data;
+       int id = netdev->dev_port;
+       struct urb *int_urb;
+       int rx_urb_cnt;
+       int ret;
+
+       for (rx_urb_cnt = 0; rx_urb_cnt < F81604_MAX_RX_URBS; ++rx_urb_cnt) {
+               struct f81604_can_frame *frame;
+               struct urb *rx_urb;
+
+               rx_urb = usb_alloc_urb(0, GFP_KERNEL);
+               if (!rx_urb) {
+                       ret = -ENOMEM;
+                       break;
+               }
+
+               frame = kmalloc(sizeof(*frame), GFP_KERNEL);
+               if (!frame) {
+                       usb_free_urb(rx_urb);
+                       ret = -ENOMEM;
+                       break;
+               }
+
+               usb_fill_bulk_urb(rx_urb, priv->dev,
+                                 usb_rcvbulkpipe(priv->dev, bulk_in_addr[id]),
+                                 frame, sizeof(*frame),
+                                 f81604_read_bulk_callback, netdev);
+
+               rx_urb->transfer_flags |= URB_FREE_BUFFER;
+               usb_anchor_urb(rx_urb, &priv->urbs_anchor);
+
+               ret = usb_submit_urb(rx_urb, GFP_KERNEL);
+               if (ret) {
+                       usb_unanchor_urb(rx_urb);
+                       usb_free_urb(rx_urb);
+                       break;
+               }
+
+               /* Drop reference, USB core will take care of freeing it */
+               usb_free_urb(rx_urb);
+       }
+
+       if (rx_urb_cnt == 0) {
+               netdev_warn(netdev, "%s: submit rx urb failed: %pe\n",
+                           __func__, ERR_PTR(ret));
+
+               goto error;
+       }
+
+       int_urb = usb_alloc_urb(0, GFP_KERNEL);
+       if (!int_urb) {
+               ret = -ENOMEM;
+               goto error;
+       }
+
+       int_data = kmalloc(sizeof(*int_data), GFP_KERNEL);
+       if (!int_data) {
+               usb_free_urb(int_urb);
+               ret = -ENOMEM;
+               goto error;
+       }
+
+       usb_fill_int_urb(int_urb, priv->dev,
+                        usb_rcvintpipe(priv->dev, int_in_addr[id]), int_data,
+                        sizeof(*int_data), f81604_read_int_callback, netdev,
+                        1);
+
+       int_urb->transfer_flags |= URB_FREE_BUFFER;
+       usb_anchor_urb(int_urb, &priv->urbs_anchor);
+
+       ret = usb_submit_urb(int_urb, GFP_KERNEL);
+       if (ret) {
+               usb_unanchor_urb(int_urb);
+               usb_free_urb(int_urb);
+
+               netdev_warn(netdev, "%s: submit int urb failed: %pe\n",
+                           __func__, ERR_PTR(ret));
+               goto error;
+       }
+
+       /* Drop reference, USB core will take care of freeing it */
+       usb_free_urb(int_urb);
+
+       return 0;
+
+error:
+       f81604_unregister_urbs(priv);
+       return ret;
+}
+
+static int f81604_start(struct net_device *netdev)
+{
+       struct f81604_port_priv *priv = netdev_priv(netdev);
+       int ret;
+       u8 mode;
+       u8 tmp;
+
+       mode = F81604_RX_AUTO_RELEASE_BUF | F81604_INT_WHEN_CHANGE;
+
+       /* Set TR/AT mode */
+       if (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT)
+               mode |= F81604_TX_ONESHOT;
+       else
+               mode |= F81604_TX_NORMAL;
+
+       ret = f81604_sja1000_write(priv, F81604_CTRL_MODE_REG, mode);
+       if (ret)
+               return ret;
+
+       /* set reset mode */
+       ret = f81604_set_reset_mode(priv);
+       if (ret)
+               return ret;
+
+       ret = f81604_chipset_init(priv);
+       if (ret)
+               return ret;
+
+       /* Clear error counters and error code capture */
+       ret = f81604_sja1000_write(priv, F81604_SJA1000_TXERR, 0);
+       if (ret)
+               return ret;
+
+       ret = f81604_sja1000_write(priv, F81604_SJA1000_RXERR, 0);
+       if (ret)
+               return ret;
+
+       /* Read clear for ECC/ALC/IR register */
+       ret = f81604_sja1000_read(priv, F81604_SJA1000_ECC, &tmp);
+       if (ret)
+               return ret;
+
+       ret = f81604_sja1000_read(priv, F81604_SJA1000_ALC, &tmp);
+       if (ret)
+               return ret;
+
+       ret = f81604_sja1000_read(priv, F81604_SJA1000_IR, &tmp);
+       if (ret)
+               return ret;
+
+       ret = f81604_register_urbs(priv);
+       if (ret)
+               return ret;
+
+       ret = f81604_set_normal_mode(priv);
+       if (ret) {
+               f81604_unregister_urbs(priv);
+               return ret;
+       }
+
+       return 0;
+}
+
+static int f81604_set_bittiming(struct net_device *dev)
+{
+       struct f81604_port_priv *priv = netdev_priv(dev);
+       struct can_bittiming *bt = &priv->can.bittiming;
+       u8 btr0, btr1;
+       int ret;
+
+       btr0 = FIELD_PREP(F81604_BRP_MASK, bt->brp - 1) |
+              FIELD_PREP(F81604_SJW_MASK, bt->sjw - 1);
+
+       btr1 = FIELD_PREP(F81604_SEG1_MASK,
+                         bt->prop_seg + bt->phase_seg1 - 1) |
+              FIELD_PREP(F81604_SEG2_MASK, bt->phase_seg2 - 1);
+
+       if (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
+               btr1 |= F81604_SJA1000_BTR1_SAMPLE_TRIPLE;
+
+       ret = f81604_sja1000_write(priv, F81604_SJA1000_BTR0, btr0);
+       if (ret) {
+               netdev_warn(dev, "%s: Set BTR0 failed: %pe\n", __func__,
+                           ERR_PTR(ret));
+               return ret;
+       }
+
+       ret = f81604_sja1000_write(priv, F81604_SJA1000_BTR1, btr1);
+       if (ret) {
+               netdev_warn(dev, "%s: Set BTR1 failed: %pe\n", __func__,
+                           ERR_PTR(ret));
+               return ret;
+       }
+
+       return 0;
+}
+
+static int f81604_set_mode(struct net_device *netdev, enum can_mode mode)
+{
+       int ret;
+
+       switch (mode) {
+       case CAN_MODE_START:
+               ret = f81604_start(netdev);
+               if (!ret && netif_queue_stopped(netdev))
+                       netif_wake_queue(netdev);
+               break;
+
+       default:
+               ret = -EOPNOTSUPP;
+       }
+
+       return ret;
+}
+
+static void f81604_write_bulk_callback(struct urb *urb)
+{
+       struct net_device *netdev = urb->context;
+
+       if (!netif_device_present(netdev))
+               return;
+
+       if (urb->status)
+               netdev_info(netdev, "%s: Tx URB error: %pe\n", __func__,
+                           ERR_PTR(urb->status));
+}
+
+static void f81604_clear_reg_work(struct work_struct *work)
+{
+       struct f81604_port_priv *priv;
+       u8 tmp;
+
+       priv = container_of(work, struct f81604_port_priv, clear_reg_work);
+
+       /* dummy read for clear Arbitration lost capture(ALC) register. */
+       if (test_and_clear_bit(F81604_CLEAR_ALC, &priv->clear_flags))
+               f81604_sja1000_read(priv, F81604_SJA1000_ALC, &tmp);
+
+       /* dummy read for clear Error code capture(ECC) register. */
+       if (test_and_clear_bit(F81604_CLEAR_ECC, &priv->clear_flags))
+               f81604_sja1000_read(priv, F81604_SJA1000_ECC, &tmp);
+
+       /* dummy write for clear data overrun flag. */
+       if (test_and_clear_bit(F81604_CLEAR_OVERRUN, &priv->clear_flags))
+               f81604_sja1000_write(priv, F81604_SJA1000_CMR,
+                                    F81604_SJA1000_CMD_CDO);
+}
+
+static netdev_tx_t f81604_start_xmit(struct sk_buff *skb,
+                                    struct net_device *netdev)
+{
+       struct can_frame *cf = (struct can_frame *)skb->data;
+       struct f81604_port_priv *priv = netdev_priv(netdev);
+       struct net_device_stats *stats = &netdev->stats;
+       struct f81604_can_frame *frame;
+       struct urb *write_urb;
+       int ret;
+
+       if (can_dev_dropped_skb(netdev, skb))
+               return NETDEV_TX_OK;
+
+       netif_stop_queue(netdev);
+
+       write_urb = usb_alloc_urb(0, GFP_ATOMIC);
+       if (!write_urb)
+               goto nomem_urb;
+
+       frame = kzalloc(sizeof(*frame), GFP_ATOMIC);
+       if (!frame)
+               goto nomem_buf;
+
+       usb_fill_bulk_urb(write_urb, priv->dev,
+                         usb_sndbulkpipe(priv->dev,
+                                         bulk_out_addr[netdev->dev_port]),
+                         frame, sizeof(*frame), f81604_write_bulk_callback,
+                         priv->netdev);
+
+       write_urb->transfer_flags |= URB_FREE_BUFFER;
+
+       frame->cmd = F81604_CMD_DATA;
+       frame->dlc = cf->len;
+
+       if (cf->can_id & CAN_RTR_FLAG)
+               frame->dlc |= F81604_DLC_RTR_BIT;
+
+       if (cf->can_id & CAN_EFF_FLAG) {
+               u32 id = (cf->can_id & CAN_EFF_MASK) << F81604_EFF_SHIFT;
+
+               put_unaligned_be32(id, &frame->eff.id);
+
+               frame->dlc |= F81604_DLC_EFF_BIT;
+
+               if (!(cf->can_id & CAN_RTR_FLAG))
+                       memcpy(&frame->eff.data, cf->data, cf->len);
+       } else {
+               u32 id = (cf->can_id & CAN_SFF_MASK) << F81604_SFF_SHIFT;
+
+               put_unaligned_be16(id, &frame->sff.id);
+
+               if (!(cf->can_id & CAN_RTR_FLAG))
+                       memcpy(&frame->sff.data, cf->data, cf->len);
+       }
+
+       can_put_echo_skb(skb, netdev, 0, 0);
+
+       ret = usb_submit_urb(write_urb, GFP_ATOMIC);
+       if (ret) {
+               netdev_err(netdev, "%s: failed to resubmit tx bulk urb: %pe\n",
+                          __func__, ERR_PTR(ret));
+
+               can_free_echo_skb(netdev, 0, NULL);
+               stats->tx_dropped++;
+               stats->tx_errors++;
+
+               if (ret == -ENODEV)
+                       netif_device_detach(netdev);
+               else
+                       netif_wake_queue(netdev);
+       }
+
+       /* let usb core take care of this urb */
+       usb_free_urb(write_urb);
+
+       return NETDEV_TX_OK;
+
+nomem_buf:
+       usb_free_urb(write_urb);
+
+nomem_urb:
+       dev_kfree_skb(skb);
+       stats->tx_dropped++;
+       stats->tx_errors++;
+       netif_wake_queue(netdev);
+
+       return NETDEV_TX_OK;
+}
+
+static int f81604_get_berr_counter(const struct net_device *netdev,
+                                  struct can_berr_counter *bec)
+{
+       struct f81604_port_priv *priv = netdev_priv(netdev);
+       u8 txerr, rxerr;
+       int ret;
+
+       ret = f81604_sja1000_read(priv, F81604_SJA1000_TXERR, &txerr);
+       if (ret)
+               return ret;
+
+       ret = f81604_sja1000_read(priv, F81604_SJA1000_RXERR, &rxerr);
+       if (ret)
+               return ret;
+
+       bec->txerr = txerr;
+       bec->rxerr = rxerr;
+
+       return 0;
+}
+
+/* Open USB device */
+static int f81604_open(struct net_device *netdev)
+{
+       int ret;
+
+       ret = open_candev(netdev);
+       if (ret)
+               return ret;
+
+       ret = f81604_start(netdev);
+       if (ret) {
+               if (ret == -ENODEV)
+                       netif_device_detach(netdev);
+
+               close_candev(netdev);
+               return ret;
+       }
+
+       netif_start_queue(netdev);
+       return 0;
+}
+
+/* Close USB device */
+static int f81604_close(struct net_device *netdev)
+{
+       struct f81604_port_priv *priv = netdev_priv(netdev);
+
+       f81604_set_reset_mode(priv);
+
+       netif_stop_queue(netdev);
+       cancel_work_sync(&priv->clear_reg_work);
+       close_candev(netdev);
+
+       f81604_unregister_urbs(priv);
+
+       return 0;
+}
+
+static const struct net_device_ops f81604_netdev_ops = {
+       .ndo_open = f81604_open,
+       .ndo_stop = f81604_close,
+       .ndo_start_xmit = f81604_start_xmit,
+       .ndo_change_mtu = can_change_mtu,
+};
+
+static const struct can_bittiming_const f81604_bittiming_const = {
+       .name = KBUILD_MODNAME,
+       .tseg1_min = 1,
+       .tseg1_max = 16,
+       .tseg2_min = 1,
+       .tseg2_max = 8,
+       .sjw_max = 4,
+       .brp_min = 1,
+       .brp_max = 64,
+       .brp_inc = 1,
+};
+
+/* Called by the usb core when driver is unloaded or device is removed */
+static void f81604_disconnect(struct usb_interface *intf)
+{
+       struct f81604_priv *priv = usb_get_intfdata(intf);
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(priv->netdev); ++i) {
+               if (!priv->netdev[i])
+                       continue;
+
+               unregister_netdev(priv->netdev[i]);
+               free_candev(priv->netdev[i]);
+       }
+}
+
+static int __f81604_set_termination(struct usb_device *dev, int idx, u16 term)
+{
+       u8 mask, data = 0;
+
+       if (idx == 0)
+               mask = F81604_CAN0_TERM;
+       else
+               mask = F81604_CAN1_TERM;
+
+       if (term)
+               data = mask;
+
+       return f81604_update_bits(dev, F81604_TERMINATOR_REG, mask, data);
+}
+
+static int f81604_set_termination(struct net_device *netdev, u16 term)
+{
+       struct f81604_port_priv *port_priv = netdev_priv(netdev);
+
+       ASSERT_RTNL();
+
+       return __f81604_set_termination(port_priv->dev, netdev->dev_port,
+                                       term);
+}
+
+static int f81604_probe(struct usb_interface *intf,
+                       const struct usb_device_id *id)
+{
+       struct usb_device *dev = interface_to_usbdev(intf);
+       struct net_device *netdev;
+       struct f81604_priv *priv;
+       int i, ret;
+
+       priv = devm_kzalloc(&intf->dev, sizeof(*priv), GFP_KERNEL);
+       if (!priv)
+               return -ENOMEM;
+
+       usb_set_intfdata(intf, priv);
+
+       for (i = 0; i < ARRAY_SIZE(priv->netdev); ++i) {
+               ret = __f81604_set_termination(dev, i, 0);
+               if (ret) {
+                       dev_err(&intf->dev,
+                               "Setting termination of CH#%d failed: %pe\n",
+                               i, ERR_PTR(ret));
+                       return ret;
+               }
+       }
+
+       for (i = 0; i < ARRAY_SIZE(priv->netdev); ++i) {
+               struct f81604_port_priv *port_priv;
+
+               netdev = alloc_candev(sizeof(*port_priv), 1);
+               if (!netdev) {
+                       dev_err(&intf->dev, "Couldn't alloc candev: %d\n", i);
+                       ret = -ENOMEM;
+
+                       goto failure_cleanup;
+               }
+
+               port_priv = netdev_priv(netdev);
+
+               INIT_WORK(&port_priv->clear_reg_work, f81604_clear_reg_work);
+               init_usb_anchor(&port_priv->urbs_anchor);
+
+               port_priv->intf = intf;
+               port_priv->dev = dev;
+               port_priv->netdev = netdev;
+               port_priv->can.clock.freq = F81604_CAN_CLOCK;
+
+               port_priv->can.termination_const = f81604_termination;
+               port_priv->can.termination_const_cnt =
+                       ARRAY_SIZE(f81604_termination);
+               port_priv->can.bittiming_const = &f81604_bittiming_const;
+               port_priv->can.do_set_bittiming = f81604_set_bittiming;
+               port_priv->can.do_set_mode = f81604_set_mode;
+               port_priv->can.do_set_termination = f81604_set_termination;
+               port_priv->can.do_get_berr_counter = f81604_get_berr_counter;
+               port_priv->can.ctrlmode_supported =
+                       CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_3_SAMPLES |
+                       CAN_CTRLMODE_ONE_SHOT | CAN_CTRLMODE_BERR_REPORTING |
+                       CAN_CTRLMODE_PRESUME_ACK;
+
+               netdev->ethtool_ops = &f81604_ethtool_ops;
+               netdev->netdev_ops = &f81604_netdev_ops;
+               netdev->flags |= IFF_ECHO;
+               netdev->dev_port = i;
+
+               SET_NETDEV_DEV(netdev, &intf->dev);
+
+               ret = register_candev(netdev);
+               if (ret) {
+                       netdev_err(netdev, "register CAN device failed: %pe\n",
+                                  ERR_PTR(ret));
+                       free_candev(netdev);
+
+                       goto failure_cleanup;
+               }
+
+               priv->netdev[i] = netdev;
+       }
+
+       return 0;
+
+failure_cleanup:
+       f81604_disconnect(intf);
+       return ret;
+}
+
+static struct usb_driver f81604_driver = {
+       .name = KBUILD_MODNAME,
+       .probe = f81604_probe,
+       .disconnect = f81604_disconnect,
+       .id_table = f81604_table,
+};
+
+module_usb_driver(f81604_driver);
+
+MODULE_AUTHOR("Ji-Ze Hong (Peter Hong) <peter_hong@fintek.com.tw>");
+MODULE_DESCRIPTION("Fintek F81604 USB to 2xCANBUS");
+MODULE_LICENSE("GPL");