xref: /openbmc/linux/drivers/net/can/usb/f81604.c (revision 278002edb19bce2c628fafb0af936e77000f3a5b)

// 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++;

		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) {
			stats->tx_errors++;
			if (skb)
				cf->data[2] |= CAN_ERR_PROT_TX;
		} else {
			stats->rx_errors++;
		}

		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");