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// SPDX-License-Identifier: GPL-2.0
/* Nuvoton NCT6694 Socket CANfd driver based on USB interface.
 *
 * Copyright (C) 2025 Nuvoton Technology Corp.
 */

#include <linux/bitfield.h>
#include <linux/can/dev.h>
#include <linux/can/rx-offload.h>
#include <linux/ethtool.h>
#include <linux/idr.h>
#include <linux/irqdomain.h>
#include <linux/kernel.h>
#include <linux/mfd/nct6694.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/platform_device.h>

#define DEVICE_NAME "nct6694-canfd"

/* USB command module type for NCT6694 CANfd controller.
 * This defines the module type used for communication with the NCT6694
 * CANfd controller over the USB interface.
 */
#define NCT6694_CANFD_MOD			0x05

/* Command 00h - CAN Setting and Initialization */
#define NCT6694_CANFD_SETTING			0x00
#define NCT6694_CANFD_SETTING_ACTIVE_CTRL1	BIT(0)
#define NCT6694_CANFD_SETTING_ACTIVE_CTRL2	BIT(1)
#define NCT6694_CANFD_SETTING_ACTIVE_NBTP_DBTP	BIT(2)
#define NCT6694_CANFD_SETTING_CTRL1_MON		BIT(0)
#define NCT6694_CANFD_SETTING_CTRL1_NISO	BIT(1)
#define NCT6694_CANFD_SETTING_CTRL1_LBCK	BIT(2)
#define NCT6694_CANFD_SETTING_NBTP_NTSEG2	GENMASK(6, 0)
#define NCT6694_CANFD_SETTING_NBTP_NTSEG1	GENMASK(15, 8)
#define NCT6694_CANFD_SETTING_NBTP_NBRP		GENMASK(24, 16)
#define NCT6694_CANFD_SETTING_NBTP_NSJW		GENMASK(31, 25)
#define NCT6694_CANFD_SETTING_DBTP_DSJW		GENMASK(3, 0)
#define NCT6694_CANFD_SETTING_DBTP_DTSEG2	GENMASK(7, 4)
#define NCT6694_CANFD_SETTING_DBTP_DTSEG1	GENMASK(12, 8)
#define NCT6694_CANFD_SETTING_DBTP_DBRP		GENMASK(20, 16)
#define NCT6694_CANFD_SETTING_DBTP_TDC		BIT(23)

/* Command 01h - CAN Information */
#define NCT6694_CANFD_INFORMATION		0x01
#define NCT6694_CANFD_INFORMATION_SEL		0x00

/* Command 02h - CAN Event */
#define NCT6694_CANFD_EVENT			0x02
#define NCT6694_CANFD_EVENT_SEL(idx, mask)	\
	((idx ? 0x80 : 0x00) | ((mask) & 0x7F))

#define NCT6694_CANFD_EVENT_MASK		GENMASK(5, 0)
#define NCT6694_CANFD_EVT_TX_FIFO_EMPTY		BIT(7)	/* Read-clear */
#define NCT6694_CANFD_EVT_RX_DATA_LOST		BIT(5)	/* Read-clear */
#define NCT6694_CANFD_EVT_RX_DATA_IN		BIT(7)	/* Read-clear */

/* Command 10h - CAN Deliver */
#define NCT6694_CANFD_DELIVER			0x10
#define NCT6694_CANFD_DELIVER_SEL(buf_cnt)	\
	((buf_cnt) & 0xFF)

/* Command 11h - CAN Receive */
#define NCT6694_CANFD_RECEIVE			0x11
#define NCT6694_CANFD_RECEIVE_SEL(idx, buf_cnt)	\
	((idx ? 0x80 : 0x00) | ((buf_cnt) & 0x7F))

#define NCT6694_CANFD_FRAME_TAG(idx)		(0xC0 | (idx))
#define NCT6694_CANFD_FRAME_FLAG_EFF		BIT(0)
#define NCT6694_CANFD_FRAME_FLAG_RTR		BIT(1)
#define NCT6694_CANFD_FRAME_FLAG_FD		BIT(2)
#define NCT6694_CANFD_FRAME_FLAG_BRS		BIT(3)
#define NCT6694_CANFD_FRAME_FLAG_ERR		BIT(4)

#define NCT6694_NAPI_WEIGHT			32

enum nct6694_event_err {
	NCT6694_CANFD_EVT_ERR_NO_ERROR = 0,
	NCT6694_CANFD_EVT_ERR_CRC_ERROR,
	NCT6694_CANFD_EVT_ERR_STUFF_ERROR,
	NCT6694_CANFD_EVT_ERR_ACK_ERROR,
	NCT6694_CANFD_EVT_ERR_FORM_ERROR,
	NCT6694_CANFD_EVT_ERR_BIT_ERROR,
	NCT6694_CANFD_EVT_ERR_TIMEOUT_ERROR,
	NCT6694_CANFD_EVT_ERR_UNKNOWN_ERROR,
};

enum nct6694_event_status {
	NCT6694_CANFD_EVT_STS_ERROR_ACTIVE = 0,
	NCT6694_CANFD_EVT_STS_ERROR_PASSIVE,
	NCT6694_CANFD_EVT_STS_BUS_OFF,
	NCT6694_CANFD_EVT_STS_WARNING,
};

struct __packed nct6694_canfd_setting {
	__le32 nbr;
	__le32 dbr;
	u8 active;
	u8 reserved[3];
	__le16 ctrl1;
	__le16 ctrl2;
	__le32 nbtp;
	__le32 dbtp;
};

struct __packed nct6694_canfd_information {
	u8 tx_fifo_cnt;
	u8 rx_fifo_cnt;
	u8 reserved[2];
	__le32 can_clk;
};

struct __packed nct6694_canfd_event {
	u8 err;
	u8 status;
	u8 tx_evt;
	u8 rx_evt;
	u8 rec;
	u8 tec;
	u8 reserved[2];
};

struct __packed nct6694_canfd_frame {
	u8 tag;
	u8 flag;
	u8 reserved;
	u8 length;
	__le32 id;
	u8 data[CANFD_MAX_DLEN];
};

struct nct6694_canfd_priv {
	struct can_priv can;	/* must be the first member */
	struct can_rx_offload offload;
	struct net_device *ndev;
	struct nct6694 *nct6694;
	struct workqueue_struct *wq;
	struct work_struct tx_work;
	struct nct6694_canfd_frame tx;
	struct nct6694_canfd_frame rx;
	struct nct6694_canfd_event event[2];
	struct can_berr_counter bec;
};

static inline struct nct6694_canfd_priv *rx_offload_to_priv(struct can_rx_offload *offload)
{
	return container_of(offload, struct nct6694_canfd_priv, offload);
}

static const struct can_bittiming_const nct6694_canfd_bittiming_nominal_const = {
	.name = DEVICE_NAME,
	.tseg1_min = 1,
	.tseg1_max = 256,
	.tseg2_min = 1,
	.tseg2_max = 128,
	.sjw_max = 128,
	.brp_min = 1,
	.brp_max = 512,
	.brp_inc = 1,
};

static const struct can_bittiming_const nct6694_canfd_bittiming_data_const = {
	.name = DEVICE_NAME,
	.tseg1_min = 1,
	.tseg1_max = 32,
	.tseg2_min = 1,
	.tseg2_max = 16,
	.sjw_max = 16,
	.brp_min = 1,
	.brp_max = 32,
	.brp_inc = 1,
};

static void nct6694_canfd_rx_offload(struct can_rx_offload *offload,
				     struct sk_buff *skb)
{
	struct nct6694_canfd_priv *priv = rx_offload_to_priv(offload);
	int ret;

	ret = can_rx_offload_queue_tail(offload, skb);
	if (ret)
		priv->ndev->stats.rx_fifo_errors++;
}

static void nct6694_canfd_handle_lost_msg(struct net_device *ndev)
{
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
	struct net_device_stats *stats = &ndev->stats;
	struct can_frame *cf;
	struct sk_buff *skb;

	netdev_dbg(ndev, "RX FIFO overflow, message(s) lost.\n");

	stats->rx_errors++;
	stats->rx_over_errors++;

	skb = alloc_can_err_skb(ndev, &cf);
	if (!skb)
		return;

	cf->can_id |= CAN_ERR_CRTL;
	cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;

	nct6694_canfd_rx_offload(&priv->offload, skb);
}

static void nct6694_canfd_handle_rx(struct net_device *ndev, u8 rx_evt)
{
	struct net_device_stats *stats = &ndev->stats;
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
	struct nct6694_canfd_frame *frame = &priv->rx;
	const struct nct6694_cmd_header cmd_hd = {
		.mod = NCT6694_CANFD_MOD,
		.cmd = NCT6694_CANFD_RECEIVE,
		.sel = NCT6694_CANFD_RECEIVE_SEL(ndev->dev_port, 1),
		.len = cpu_to_le16(sizeof(*frame))
	};
	struct sk_buff *skb;
	int ret;

	ret = nct6694_read_msg(priv->nct6694, &cmd_hd, frame);
	if (ret)
		return;

	if (frame->flag & NCT6694_CANFD_FRAME_FLAG_FD) {
		struct canfd_frame *cfd;

		skb = alloc_canfd_skb(priv->ndev, &cfd);
		if (!skb) {
			stats->rx_dropped++;
			return;
		}

		cfd->can_id = le32_to_cpu(frame->id);
		cfd->len = canfd_sanitize_len(frame->length);
		if (frame->flag & NCT6694_CANFD_FRAME_FLAG_EFF)
			cfd->can_id |= CAN_EFF_FLAG;
		if (frame->flag & NCT6694_CANFD_FRAME_FLAG_BRS)
			cfd->flags |= CANFD_BRS;
		if (frame->flag & NCT6694_CANFD_FRAME_FLAG_ERR)
			cfd->flags |= CANFD_ESI;

		memcpy(cfd->data, frame->data, cfd->len);
	} else {
		struct can_frame *cf;

		skb = alloc_can_skb(priv->ndev, &cf);
		if (!skb) {
			stats->rx_dropped++;
			return;
		}

		cf->can_id = le32_to_cpu(frame->id);
		cf->len = can_cc_dlc2len(frame->length);
		if (frame->flag & NCT6694_CANFD_FRAME_FLAG_EFF)
			cf->can_id |= CAN_EFF_FLAG;

		if (frame->flag & NCT6694_CANFD_FRAME_FLAG_RTR)
			cf->can_id |= CAN_RTR_FLAG;
		else
			memcpy(cf->data, frame->data, cf->len);
	}

	nct6694_canfd_rx_offload(&priv->offload, skb);
}

static int nct6694_canfd_get_berr_counter(const struct net_device *ndev,
					  struct can_berr_counter *bec)
{
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);

	*bec = priv->bec;

	return 0;
}

static void nct6694_canfd_handle_state_change(struct net_device *ndev, u8 status)
{
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
	enum can_state new_state, rx_state, tx_state;
	struct can_berr_counter bec;
	struct can_frame *cf;
	struct sk_buff *skb;

	nct6694_canfd_get_berr_counter(ndev, &bec);
	can_state_get_by_berr_counter(ndev, &bec, &tx_state, &rx_state);

	new_state = max(tx_state, rx_state);

	/* state hasn't changed */
	if (new_state == priv->can.state)
		return;

	skb = alloc_can_err_skb(ndev, &cf);

	can_change_state(ndev, cf, tx_state, rx_state);

	if (new_state == CAN_STATE_BUS_OFF) {
		can_bus_off(ndev);
	} else if (cf) {
		cf->can_id |= CAN_ERR_CNT;
		cf->data[6] = bec.txerr;
		cf->data[7] = bec.rxerr;
	}

	if (skb)
		nct6694_canfd_rx_offload(&priv->offload, skb);
}

static void nct6694_canfd_handle_bus_err(struct net_device *ndev, u8 bus_err)
{
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
	struct can_frame *cf;
	struct sk_buff *skb;

	priv->can.can_stats.bus_error++;

	skb = alloc_can_err_skb(ndev, &cf);
	if (cf)
		cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;

	switch (bus_err) {
	case NCT6694_CANFD_EVT_ERR_CRC_ERROR:
		netdev_dbg(ndev, "CRC error\n");
		ndev->stats.rx_errors++;
		if (cf)
			cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ;
		break;

	case NCT6694_CANFD_EVT_ERR_STUFF_ERROR:
		netdev_dbg(ndev, "Stuff error\n");
		ndev->stats.rx_errors++;
		if (cf)
			cf->data[2] |= CAN_ERR_PROT_STUFF;
		break;

	case NCT6694_CANFD_EVT_ERR_ACK_ERROR:
		netdev_dbg(ndev, "Ack error\n");
		ndev->stats.tx_errors++;
		if (cf) {
			cf->can_id |= CAN_ERR_ACK;
			cf->data[2] |= CAN_ERR_PROT_TX;
		}
		break;

	case NCT6694_CANFD_EVT_ERR_FORM_ERROR:
		netdev_dbg(ndev, "Form error\n");
		ndev->stats.rx_errors++;
		if (cf)
			cf->data[2] |= CAN_ERR_PROT_FORM;
		break;

	case NCT6694_CANFD_EVT_ERR_BIT_ERROR:
		netdev_dbg(ndev, "Bit error\n");
		ndev->stats.tx_errors++;
		if (cf)
			cf->data[2] |= CAN_ERR_PROT_TX | CAN_ERR_PROT_BIT;
		break;

	default:
		break;
	}

	if (skb)
		nct6694_canfd_rx_offload(&priv->offload, skb);
}

static void nct6694_canfd_handle_tx(struct net_device *ndev)
{
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
	struct net_device_stats *stats = &ndev->stats;

	stats->tx_bytes += can_rx_offload_get_echo_skb_queue_tail(&priv->offload,
								  0, NULL);
	stats->tx_packets++;
	netif_wake_queue(ndev);
}

static irqreturn_t nct6694_canfd_irq(int irq, void *data)
{
	struct net_device *ndev = data;
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
	struct nct6694_canfd_event *event = &priv->event[ndev->dev_port];
	const struct nct6694_cmd_header cmd_hd = {
		.mod = NCT6694_CANFD_MOD,
		.cmd = NCT6694_CANFD_EVENT,
		.sel = NCT6694_CANFD_EVENT_SEL(ndev->dev_port, NCT6694_CANFD_EVENT_MASK),
		.len = cpu_to_le16(sizeof(priv->event))
	};
	irqreturn_t handled = IRQ_NONE;
	int ret;

	ret = nct6694_read_msg(priv->nct6694, &cmd_hd, priv->event);
	if (ret < 0)
		return handled;

	if (event->rx_evt & NCT6694_CANFD_EVT_RX_DATA_IN) {
		nct6694_canfd_handle_rx(ndev, event->rx_evt);
		handled = IRQ_HANDLED;
	}

	if (event->rx_evt & NCT6694_CANFD_EVT_RX_DATA_LOST) {
		nct6694_canfd_handle_lost_msg(ndev);
		handled = IRQ_HANDLED;
	}

	if (event->status) {
		nct6694_canfd_handle_state_change(ndev, event->status);
		handled = IRQ_HANDLED;
	}

	if (event->err != NCT6694_CANFD_EVT_ERR_NO_ERROR) {
		if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
			nct6694_canfd_handle_bus_err(ndev, event->err);
		handled = IRQ_HANDLED;
	}

	if (event->tx_evt & NCT6694_CANFD_EVT_TX_FIFO_EMPTY) {
		nct6694_canfd_handle_tx(ndev);
		handled = IRQ_HANDLED;
	}

	if (handled)
		can_rx_offload_threaded_irq_finish(&priv->offload);

	priv->bec.rxerr = event->rec;
	priv->bec.txerr = event->tec;

	return handled;
}

static void nct6694_canfd_tx_work(struct work_struct *work)
{
	struct nct6694_canfd_priv *priv = container_of(work,
						       struct nct6694_canfd_priv,
						       tx_work);
	struct nct6694_canfd_frame *frame = &priv->tx;
	struct net_device *ndev = priv->ndev;
	struct net_device_stats *stats = &ndev->stats;
	struct sk_buff *skb = priv->can.echo_skb[0];
	static const struct nct6694_cmd_header cmd_hd = {
		.mod = NCT6694_CANFD_MOD,
		.cmd = NCT6694_CANFD_DELIVER,
		.sel = NCT6694_CANFD_DELIVER_SEL(1),
		.len = cpu_to_le16(sizeof(*frame))
	};
	u32 txid;
	int err;

	memset(frame, 0, sizeof(*frame));

	frame->tag = NCT6694_CANFD_FRAME_TAG(ndev->dev_port);

	if (can_is_canfd_skb(skb)) {
		struct canfd_frame *cfd = (struct canfd_frame *)skb->data;

		if (cfd->flags & CANFD_BRS)
			frame->flag |= NCT6694_CANFD_FRAME_FLAG_BRS;

		if (cfd->can_id & CAN_EFF_FLAG) {
			txid = cfd->can_id & CAN_EFF_MASK;
			frame->flag |= NCT6694_CANFD_FRAME_FLAG_EFF;
		} else {
			txid = cfd->can_id & CAN_SFF_MASK;
		}
		frame->flag |= NCT6694_CANFD_FRAME_FLAG_FD;
		frame->id = cpu_to_le32(txid);
		frame->length = canfd_sanitize_len(cfd->len);

		memcpy(frame->data, cfd->data, frame->length);
	} else {
		struct can_frame *cf = (struct can_frame *)skb->data;

		if (cf->can_id & CAN_EFF_FLAG) {
			txid = cf->can_id & CAN_EFF_MASK;
			frame->flag |= NCT6694_CANFD_FRAME_FLAG_EFF;
		} else {
			txid = cf->can_id & CAN_SFF_MASK;
		}

		if (cf->can_id & CAN_RTR_FLAG)
			frame->flag |= NCT6694_CANFD_FRAME_FLAG_RTR;
		else
			memcpy(frame->data, cf->data, cf->len);

		frame->id = cpu_to_le32(txid);
		frame->length = cf->len;
	}

	err = nct6694_write_msg(priv->nct6694, &cmd_hd, frame);
	if (err) {
		can_free_echo_skb(ndev, 0, NULL);
		stats->tx_dropped++;
		stats->tx_errors++;
		netif_wake_queue(ndev);
	}
}

static netdev_tx_t nct6694_canfd_start_xmit(struct sk_buff *skb,
					    struct net_device *ndev)
{
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);

	if (can_dev_dropped_skb(ndev, skb))
		return NETDEV_TX_OK;

	netif_stop_queue(ndev);
	can_put_echo_skb(skb, ndev, 0, 0);
	queue_work(priv->wq, &priv->tx_work);

	return NETDEV_TX_OK;
}

static int nct6694_canfd_start(struct net_device *ndev)
{
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
	const struct can_bittiming *n_bt = &priv->can.bittiming;
	const struct can_bittiming *d_bt = &priv->can.fd.data_bittiming;
	struct nct6694_canfd_setting *setting __free(kfree) = NULL;
	const struct nct6694_cmd_header cmd_hd = {
		.mod = NCT6694_CANFD_MOD,
		.cmd = NCT6694_CANFD_SETTING,
		.sel = ndev->dev_port,
		.len = cpu_to_le16(sizeof(*setting))
	};
	u32 en_tdc;
	int ret;

	setting = kzalloc(sizeof(*setting), GFP_KERNEL);
	if (!setting)
		return -ENOMEM;

	if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
		setting->ctrl1 |= cpu_to_le16(NCT6694_CANFD_SETTING_CTRL1_MON);

	if (priv->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)
		setting->ctrl1 |= cpu_to_le16(NCT6694_CANFD_SETTING_CTRL1_NISO);

	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
		setting->ctrl1 |= cpu_to_le16(NCT6694_CANFD_SETTING_CTRL1_LBCK);

	/* Disable clock divider */
	setting->ctrl2 = 0;

	setting->nbtp = cpu_to_le32(FIELD_PREP(NCT6694_CANFD_SETTING_NBTP_NSJW,
					       n_bt->sjw - 1) |
				    FIELD_PREP(NCT6694_CANFD_SETTING_NBTP_NBRP,
					       n_bt->brp - 1) |
				    FIELD_PREP(NCT6694_CANFD_SETTING_NBTP_NTSEG2,
					       n_bt->phase_seg2 - 1) |
				    FIELD_PREP(NCT6694_CANFD_SETTING_NBTP_NTSEG1,
					       n_bt->prop_seg + n_bt->phase_seg1 - 1));

	if (d_bt->brp <= 2)
		en_tdc = NCT6694_CANFD_SETTING_DBTP_TDC;
	else
		en_tdc = 0;

	setting->dbtp = cpu_to_le32(FIELD_PREP(NCT6694_CANFD_SETTING_DBTP_DSJW,
					       d_bt->sjw - 1) |
				    FIELD_PREP(NCT6694_CANFD_SETTING_DBTP_DBRP,
					       d_bt->brp - 1) |
				    FIELD_PREP(NCT6694_CANFD_SETTING_DBTP_DTSEG2,
					       d_bt->phase_seg2 - 1) |
				    FIELD_PREP(NCT6694_CANFD_SETTING_DBTP_DTSEG1,
					       d_bt->prop_seg + d_bt->phase_seg1 - 1) |
				    en_tdc);

	setting->active = NCT6694_CANFD_SETTING_ACTIVE_CTRL1 |
			  NCT6694_CANFD_SETTING_ACTIVE_CTRL2 |
			  NCT6694_CANFD_SETTING_ACTIVE_NBTP_DBTP;

	ret = nct6694_write_msg(priv->nct6694, &cmd_hd, setting);
	if (ret)
		return ret;

	priv->can.state = CAN_STATE_ERROR_ACTIVE;

	return 0;
}

static void nct6694_canfd_stop(struct net_device *ndev)
{
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
	struct nct6694_canfd_setting *setting __free(kfree) = NULL;
	const struct nct6694_cmd_header cmd_hd = {
		.mod = NCT6694_CANFD_MOD,
		.cmd = NCT6694_CANFD_SETTING,
		.sel = ndev->dev_port,
		.len = cpu_to_le16(sizeof(*setting))
	};

	/* The NCT6694 cannot be stopped. To ensure safe operation and avoid
	 * interference, the control mode is set to Listen-Only mode. This
	 * mode allows the device to monitor bus activity without actively
	 * participating in communication.
	 */
	setting = kzalloc(sizeof(*setting), GFP_KERNEL);
	if (!setting)
		return;

	nct6694_read_msg(priv->nct6694, &cmd_hd, setting);
	setting->ctrl1 = cpu_to_le16(NCT6694_CANFD_SETTING_CTRL1_MON);
	setting->active = NCT6694_CANFD_SETTING_ACTIVE_CTRL1;
	nct6694_write_msg(priv->nct6694, &cmd_hd, setting);

	priv->can.state = CAN_STATE_STOPPED;
}

static int nct6694_canfd_close(struct net_device *ndev)
{
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);

	netif_stop_queue(ndev);
	nct6694_canfd_stop(ndev);
	destroy_workqueue(priv->wq);
	free_irq(ndev->irq, ndev);
	can_rx_offload_disable(&priv->offload);
	close_candev(ndev);
	return 0;
}

static int nct6694_canfd_set_mode(struct net_device *ndev, enum can_mode mode)
{
	int ret;

	switch (mode) {
	case CAN_MODE_START:
		ret = nct6694_canfd_start(ndev);
		if (ret)
			return ret;

		netif_wake_queue(ndev);
		break;

	default:
		return -EOPNOTSUPP;
	}

	return ret;
}

static int nct6694_canfd_open(struct net_device *ndev)
{
	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
	int ret;

	ret = open_candev(ndev);
	if (ret)
		return ret;

	can_rx_offload_enable(&priv->offload);

	ret = request_threaded_irq(ndev->irq, NULL,
				   nct6694_canfd_irq, IRQF_ONESHOT,
				   "nct6694_canfd", ndev);
	if (ret) {
		netdev_err(ndev, "Failed to request IRQ\n");
		goto can_rx_offload_disable;
	}

	priv->wq = alloc_ordered_workqueue("%s-nct6694_wq",
					   WQ_FREEZABLE | WQ_MEM_RECLAIM,
					   ndev->name);
	if (!priv->wq) {
		ret = -ENOMEM;
		goto free_irq;
	}

	ret = nct6694_canfd_start(ndev);
	if (ret)
		goto destroy_wq;

	netif_start_queue(ndev);

	return 0;

destroy_wq:
	destroy_workqueue(priv->wq);
free_irq:
	free_irq(ndev->irq, ndev);
can_rx_offload_disable:
	can_rx_offload_disable(&priv->offload);
	close_candev(ndev);
	return ret;
}

static const struct net_device_ops nct6694_canfd_netdev_ops = {
	.ndo_open = nct6694_canfd_open,
	.ndo_stop = nct6694_canfd_close,
	.ndo_start_xmit = nct6694_canfd_start_xmit,
	.ndo_change_mtu = can_change_mtu,
};

static const struct ethtool_ops nct6694_canfd_ethtool_ops = {
	.get_ts_info = ethtool_op_get_ts_info,
};

static int nct6694_canfd_get_clock(struct nct6694_canfd_priv *priv)
{
	struct nct6694_canfd_information *info __free(kfree) = NULL;
	static const struct nct6694_cmd_header cmd_hd = {
		.mod = NCT6694_CANFD_MOD,
		.cmd = NCT6694_CANFD_INFORMATION,
		.sel = NCT6694_CANFD_INFORMATION_SEL,
		.len = cpu_to_le16(sizeof(*info))
	};
	int ret;

	info = kzalloc(sizeof(*info), GFP_KERNEL);
	if (!info)
		return -ENOMEM;

	ret = nct6694_read_msg(priv->nct6694, &cmd_hd, info);
	if (ret)
		return ret;

	return le32_to_cpu(info->can_clk);
}

static int nct6694_canfd_probe(struct platform_device *pdev)
{
	struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
	struct nct6694_canfd_priv *priv;
	struct net_device *ndev;
	int port, irq, ret, can_clk;

	port = ida_alloc(&nct6694->canfd_ida, GFP_KERNEL);
	if (port < 0)
		return port;

	irq = irq_create_mapping(nct6694->domain,
				 NCT6694_IRQ_CAN0 + port);
	if (!irq) {
		ret = -EINVAL;
		goto free_ida;
	}

	ndev = alloc_candev(sizeof(struct nct6694_canfd_priv), 1);
	if (!ndev) {
		ret = -ENOMEM;
		goto dispose_irq;
	}

	ndev->irq = irq;
	ndev->flags |= IFF_ECHO;
	ndev->dev_port = port;
	ndev->netdev_ops = &nct6694_canfd_netdev_ops;
	ndev->ethtool_ops = &nct6694_canfd_ethtool_ops;

	priv = netdev_priv(ndev);
	priv->nct6694 = nct6694;
	priv->ndev = ndev;

	can_clk = nct6694_canfd_get_clock(priv);
	if (can_clk < 0) {
		ret = dev_err_probe(&pdev->dev, can_clk,
				    "Failed to get clock\n");
		goto free_candev;
	}

	INIT_WORK(&priv->tx_work, nct6694_canfd_tx_work);

	priv->can.clock.freq = can_clk;
	priv->can.bittiming_const = &nct6694_canfd_bittiming_nominal_const;
	priv->can.fd.data_bittiming_const = &nct6694_canfd_bittiming_data_const;
	priv->can.do_set_mode = nct6694_canfd_set_mode;
	priv->can.do_get_berr_counter = nct6694_canfd_get_berr_counter;
	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
		CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_BERR_REPORTING |
		CAN_CTRLMODE_FD_NON_ISO;

	ret = can_set_static_ctrlmode(ndev, CAN_CTRLMODE_FD);
	if (ret)
		goto free_candev;

	ret = can_rx_offload_add_manual(ndev, &priv->offload,
					NCT6694_NAPI_WEIGHT);
	if (ret) {
		dev_err_probe(&pdev->dev, ret, "Failed to add rx_offload\n");
		goto free_candev;
	}

	platform_set_drvdata(pdev, priv);
	SET_NETDEV_DEV(priv->ndev, &pdev->dev);

	ret = register_candev(priv->ndev);
	if (ret)
		goto rx_offload_del;

	return 0;

rx_offload_del:
	can_rx_offload_del(&priv->offload);
free_candev:
	free_candev(ndev);
dispose_irq:
	irq_dispose_mapping(irq);
free_ida:
	ida_free(&nct6694->canfd_ida, port);
	return ret;
}

static void nct6694_canfd_remove(struct platform_device *pdev)
{
	struct nct6694_canfd_priv *priv = platform_get_drvdata(pdev);
	struct nct6694 *nct6694 = priv->nct6694;
	struct net_device *ndev = priv->ndev;
	int port = ndev->dev_port;
	int irq = ndev->irq;

	unregister_candev(ndev);
	can_rx_offload_del(&priv->offload);
	free_candev(ndev);
	irq_dispose_mapping(irq);
	ida_free(&nct6694->canfd_ida, port);
}

static struct platform_driver nct6694_canfd_driver = {
	.driver = {
		.name	= DEVICE_NAME,
	},
	.probe		= nct6694_canfd_probe,
	.remove		= nct6694_canfd_remove,
};

module_platform_driver(nct6694_canfd_driver);

MODULE_DESCRIPTION("USB-CAN FD driver for NCT6694");
MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
MODULE_LICENSE("GPL");