[PATCH v5 4/7] can: Add Nuvoton NCT6694 CAN support

[Ming Yu <a0282524688@gmail.com>]

This driver supports Socket CANfd functionality for NCT6694 MFD
device based on USB interface.

Signed-off-by: Ming Yu <a0282524688@gmail.com>
---
 MAINTAINERS                         |   1 +
 drivers/net/can/usb/Kconfig         |  10 +
 drivers/net/can/usb/Makefile        |   1 +
 drivers/net/can/usb/nct6694_canfd.c | 856 ++++++++++++++++++++++++++++
 4 files changed, 868 insertions(+)
 create mode 100644 drivers/net/can/usb/nct6694_canfd.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 4e72f749cdf2..6e9b78202d6f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16724,6 +16724,7 @@ S:	Supported
 F:	drivers/gpio/gpio-nct6694.c
 F:	drivers/i2c/busses/i2c-nct6694.c
 F:	drivers/mfd/nct6694.c
+F:	drivers/net/can/usb/nct6694_canfd.c
 F:	include/linux/mfd/nct6694.h
 
 NVIDIA (rivafb and nvidiafb) FRAMEBUFFER DRIVER
diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
index 9dae0c71a2e1..53254012cdc4 100644
--- a/drivers/net/can/usb/Kconfig
+++ b/drivers/net/can/usb/Kconfig
@@ -133,6 +133,16 @@ config CAN_MCBA_USB
 	  This driver supports the CAN BUS Analyzer interface
 	  from Microchip (http://www.microchip.com/development-tools/).
 
+config CAN_NCT6694
+	tristate "Nuvoton NCT6694 Socket CANfd support"
+	depends on MFD_NCT6694
+	help
+	  If you say yes to this option, support will be included for Nuvoton
+	  NCT6694, a USB device to socket CANfd controller.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called nct6694_canfd.
+
 config CAN_PEAK_USB
 	tristate "PEAK PCAN-USB/USB Pro interfaces for CAN 2.0b/CAN-FD"
 	help
diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
index 8b11088e9a59..fcafb1ac262e 100644
--- a/drivers/net/can/usb/Makefile
+++ b/drivers/net/can/usb/Makefile
@@ -11,5 +11,6 @@ obj-$(CONFIG_CAN_F81604) += f81604.o
 obj-$(CONFIG_CAN_GS_USB) += gs_usb.o
 obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb/
 obj-$(CONFIG_CAN_MCBA_USB) += mcba_usb.o
+obj-$(CONFIG_CAN_NCT6694) += nct6694_canfd.o
 obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
 obj-$(CONFIG_CAN_UCAN) += ucan.o
diff --git a/drivers/net/can/usb/nct6694_canfd.c b/drivers/net/can/usb/nct6694_canfd.c
new file mode 100644
index 000000000000..7a15c39021ff
--- /dev/null
+++ b/drivers/net/can/usb/nct6694_canfd.c
@@ -0,0 +1,856 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Nuvoton NCT6694 Socket CANfd driver based on USB interface.
+ *
+ * Copyright (C) 2024 Nuvoton Technology Corp.
+ */
+
+#include <linux/can/dev.h>
+#include <linux/can/rx-offload.h>
+#include <linux/ethtool.h>
+#include <linux/irqdomain.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/nct6694.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/platform_device.h>
+
+#define DRVNAME "nct6694-can"
+
+/*
+ * 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_CAN_MOD			0x05
+
+/* Command 00h - CAN Setting and Initialization */
+#define NCT6694_CAN_SETTING		0x00
+#define NCT6694_CAN_SETTING_SEL(idx)	(idx ? 0x01 : 0x00)
+#define NCT6694_CAN_SETTING_CTRL1_MON	BIT(0)
+#define NCT6694_CAN_SETTING_CTRL1_NISO	BIT(1)
+#define NCT6694_CAN_SETTING_CTRL1_LBCK	BIT(2)
+
+/* Command 01h - CAN Information */
+#define NCT6694_CAN_INFORMATION		0x01
+#define NCT6694_CAN_INFORMATION_SEL	0x00
+
+/* Command 02h - CAN Event */
+#define NCT6694_CAN_EVENT		0x02
+#define NCT6694_CAN_EVENT_SEL(idx, mask)	\
+	((idx ? 0x80 : 0x00) | ((mask) & 0xFF))
+#define NCT6694_CAN_EVENT_ERR		BIT(0)
+#define NCT6694_CAN_EVENT_STATUS	BIT(1)
+#define NCT6694_CAN_EVENT_TX_EVT	BIT(2)
+#define NCT6694_CAN_EVENT_RX_EVT	BIT(3)
+#define NCT6694_CAN_EVENT_REC		BIT(4)
+#define NCT6694_CAN_EVENT_TEC		BIT(5)
+#define NCT6694_CAN_EVENT_MASK		GENMASK(3, 0)
+#define NCT6694_CAN_EVT_TX_FIFO_EMPTY	BIT(7)	/* Read-clear */
+#define NCT6694_CAN_EVT_RX_DATA_LOST	BIT(5)	/* Read-clear */
+#define NCT6694_CAN_EVT_RX_HALF_FULL	BIT(6)	/* Read-clear */
+#define NCT6694_CAN_EVT_RX_DATA_IN	BIT(7)	/* Read-clear*/
+
+/* Command 10h - CAN Deliver */
+#define NCT6694_CAN_DELIVER		0x10
+#define NCT6694_CAN_DELIVER_SEL(buf_cnt)	\
+	((buf_cnt) & 0xFF)
+
+/* Command 11h - CAN Receive */
+#define NCT6694_CAN_RECEIVE		0x11
+#define NCT6694_CAN_RECEIVE_SEL(idx, buf_cnt)	\
+	((idx ? 0x80 : 0x00) | ((buf_cnt) & 0xFF))
+
+#define NCT6694_CAN_FRAME_TAG_CAN0	0xC0
+#define NCT6694_CAN_FRAME_TAG_CAN1	0xC1
+#define NCT6694_CAN_FRAME_FLAG_EFF	BIT(0)
+#define NCT6694_CAN_FRAME_FLAG_RTR	BIT(1)
+#define NCT6694_CAN_FRAME_FLAG_FD	BIT(2)
+#define NCT6694_CAN_FRAME_FLAG_BRS	BIT(3)
+#define NCT6694_CAN_FRAME_FLAG_ERR	BIT(4)
+
+#define NCT6694_NAPI_WEIGHT		32
+
+enum nct6694_event_err {
+	NCT6694_CAN_EVT_ERR_NO_ERROR = 0,
+	NCT6694_CAN_EVT_ERR_CRC_ERROR,
+	NCT6694_CAN_EVT_ERR_STUFF_ERROR,
+	NCT6694_CAN_EVT_ERR_ACK_ERROR,
+	NCT6694_CAN_EVT_ERR_FORM_ERROR,
+	NCT6694_CAN_EVT_ERR_BIT_ERROR,
+	NCT6694_CAN_EVT_ERR_TIMEOUT_ERROR,
+	NCT6694_CAN_EVT_ERR_UNKNOWN_ERROR,
+};
+
+enum nct6694_event_status {
+	NCT6694_CAN_EVT_STS_ERROR_ACTIVE = 0,
+	NCT6694_CAN_EVT_STS_ERROR_PASSIVE,
+	NCT6694_CAN_EVT_STS_BUS_OFF,
+	NCT6694_CAN_EVT_STS_WARNING,
+};
+
+struct __packed nct6694_can_setting {
+	__le32 nbr;
+	__le32 dbr;
+	u8 active;
+	u8 reserved[3];
+	__le16 ctrl1;
+	__le16 ctrl2;
+	__le32 nbtp;
+	__le32 dbtp;
+};
+
+struct __packed nct6694_can_information {
+	u8 tx_fifo_cnt;
+	u8 rx_fifo_cnt;
+	u8 reserved[2];
+	__le32 can_clk;
+};
+
+struct __packed nct6694_can_event {
+	u8 err;
+	u8 status;
+	u8 tx_evt;
+	u8 rx_evt;
+	u8 rec;
+	u8 tec;
+	u8 reserved[2];
+};
+
+struct __packed nct6694_can_frame {
+	u8 tag;
+	u8 flag;
+	u8 reserved;
+	u8 length;
+	__le32 id;
+	u8 data[64];
+};
+
+union __packed nct6694_can_tx {
+	struct nct6694_can_frame frame;
+	struct nct6694_can_setting setting;
+};
+
+union __packed nct6694_can_rx {
+	struct nct6694_can_event event[2];
+	struct nct6694_can_frame frame;
+	struct nct6694_can_information info;
+};
+
+struct nct6694_can_priv {
+	struct can_priv can;	/* must be the first member */
+	struct can_rx_offload offload;
+	struct net_device *ndev;
+	struct nct6694 *nct6694;
+	struct mutex lock;
+	struct sk_buff *tx_skb;
+	struct workqueue_struct *wq;
+	struct work_struct tx_work;
+	union nct6694_can_tx *tx;
+	union nct6694_can_rx *rx;
+	unsigned char can_idx;
+};
+
+static inline struct nct6694_can_priv *rx_offload_to_priv(struct can_rx_offload *offload)
+{
+	return container_of(offload, struct nct6694_can_priv, offload);
+}
+
+static const struct can_bittiming_const nct6694_can_bittiming_nominal_const = {
+	.name = DRVNAME,
+	.tseg1_min = 2,
+	.tseg1_max = 256,
+	.tseg2_min = 2,
+	.tseg2_max = 128,
+	.sjw_max = 128,
+	.brp_min = 1,
+	.brp_max = 511,
+	.brp_inc = 1,
+};
+
+static const struct can_bittiming_const nct6694_can_bittiming_data_const = {
+	.name = DRVNAME,
+	.tseg1_min = 1,
+	.tseg1_max = 32,
+	.tseg2_min = 1,
+	.tseg2_max = 16,
+	.sjw_max = 16,
+	.brp_min = 1,
+	.brp_max = 31,
+	.brp_inc = 1,
+};
+
+static void nct6694_can_rx_offload(struct can_rx_offload *offload,
+				   struct sk_buff *skb)
+{
+	struct nct6694_can_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_can_handle_lost_msg(struct net_device *ndev)
+{
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+	struct can_frame *cf;
+	struct sk_buff *skb;
+
+	netdev_err(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_can_rx_offload(&priv->offload, skb);
+}
+
+static void nct6694_can_rx(struct net_device *ndev, u8 rx_evt)
+{
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+	struct nct6694_can_frame *frame = &priv->rx->frame;
+	struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_CAN_MOD,
+		.cmd = NCT6694_CAN_RECEIVE,
+		.sel = NCT6694_CAN_RECEIVE_SEL(priv->can_idx, 1),
+		.len = cpu_to_le16(sizeof(*frame))
+	};
+	struct canfd_frame *cfd;
+	struct can_frame *cf;
+	struct sk_buff *skb;
+	int ret;
+
+	ret = nct6694_read_msg(priv->nct6694, &cmd_hd, frame);
+	if (ret)
+		return;
+
+	if (frame->flag & NCT6694_CAN_FRAME_FLAG_FD) {
+		skb = alloc_canfd_skb(priv->ndev, &cfd);
+		if (!skb)
+			return;
+
+		cfd->can_id = le32_to_cpu(frame->id);
+		cfd->len = frame->length;
+		if (frame->flag & NCT6694_CAN_FRAME_FLAG_EFF)
+			cfd->can_id |= CAN_EFF_FLAG;
+		if (frame->flag & NCT6694_CAN_FRAME_FLAG_BRS)
+			cfd->flags |= CANFD_BRS;
+		if (frame->flag & NCT6694_CAN_FRAME_FLAG_ERR)
+			cfd->flags |= CANFD_ESI;
+
+		memcpy(cfd->data, frame->data, cfd->len);
+	} else {
+		skb = alloc_can_skb(priv->ndev, &cf);
+		if (!skb)
+			return;
+
+		cf->can_id = le32_to_cpu(frame->id);
+		cf->len = frame->length;
+		if (frame->flag & NCT6694_CAN_FRAME_FLAG_EFF)
+			cf->can_id |= CAN_EFF_FLAG;
+		if (frame->flag & NCT6694_CAN_FRAME_FLAG_RTR)
+			cf->can_id |= CAN_RTR_FLAG;
+
+		memcpy(cf->data, frame->data, cf->len);
+	}
+
+	nct6694_can_rx_offload(&priv->offload, skb);
+}
+
+static void nct6694_can_clean(struct net_device *ndev)
+{
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+
+	if (priv->tx_skb || netif_queue_stopped(ndev))
+		ndev->stats.tx_errors++;
+	dev_kfree_skb(priv->tx_skb);
+	priv->tx_skb = NULL;
+}
+
+static int nct6694_can_get_berr_counter(const struct net_device *ndev,
+					struct can_berr_counter *bec)
+{
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+	struct nct6694_can_event *evt = priv->rx->event;
+	struct nct6694_cmd_header cmd_hd;
+	u8 mask = NCT6694_CAN_EVENT_REC | NCT6694_CAN_EVENT_TEC;
+	int ret;
+
+	guard(mutex)(&priv->lock);
+
+	cmd_hd = (struct nct6694_cmd_header) {
+		.mod = NCT6694_CAN_MOD,
+		.cmd = NCT6694_CAN_EVENT,
+		.sel = NCT6694_CAN_EVENT_SEL(priv->can_idx, mask),
+		.len = cpu_to_le16(sizeof(priv->rx->event))
+	};
+
+	ret = nct6694_read_msg(priv->nct6694, &cmd_hd, evt);
+	if (ret < 0)
+		return ret;
+
+	bec->rxerr = evt[priv->can_idx].rec;
+	bec->txerr = evt[priv->can_idx].tec;
+
+	return 0;
+}
+
+static void nct6694_can_handle_state_change(struct net_device *ndev,
+					    u8 status)
+{
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+	enum can_state new_state = priv->can.state;
+	enum can_state rx_state, tx_state;
+	struct can_berr_counter bec;
+	struct can_frame *cf;
+	struct sk_buff *skb;
+
+	nct6694_can_get_berr_counter(ndev, &bec);
+	can_state_get_by_berr_counter(ndev, &bec, &tx_state, &rx_state);
+
+	switch (status) {
+	case NCT6694_CAN_EVT_STS_ERROR_ACTIVE:
+		new_state = CAN_STATE_ERROR_ACTIVE;
+		break;
+	case NCT6694_CAN_EVT_STS_ERROR_PASSIVE:
+		new_state = CAN_STATE_ERROR_PASSIVE;
+		break;
+	case NCT6694_CAN_EVT_STS_BUS_OFF:
+		new_state = CAN_STATE_BUS_OFF;
+		break;
+	case NCT6694_CAN_EVT_STS_WARNING:
+		new_state = CAN_STATE_ERROR_WARNING;
+		break;
+	default:
+		netdev_err(ndev, "Receive unknown CAN status event.\n");
+		return;
+	}
+
+	/* state hasn't changed */
+	if (new_state == priv->can.state)
+		return;
+
+	skb = alloc_can_err_skb(ndev, &cf);
+
+	tx_state = bec.txerr >= bec.rxerr ? new_state : 0;
+	rx_state = bec.txerr <= bec.rxerr ? new_state : 0;
+	can_change_state(ndev, cf, tx_state, rx_state);
+
+	if (new_state == CAN_STATE_BUS_OFF) {
+		can_bus_off(ndev);
+	} else if (skb) {
+		cf->can_id |= CAN_ERR_CNT;
+		cf->data[6] = bec.txerr;
+		cf->data[7] = bec.rxerr;
+	}
+
+	nct6694_can_rx_offload(&priv->offload, skb);
+}
+
+static void nct6694_handle_bus_err(struct net_device *ndev, u8 bus_err)
+{
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+	struct can_frame *cf;
+	struct sk_buff *skb;
+
+	if (bus_err == NCT6694_CAN_EVT_ERR_NO_ERROR)
+		return;
+
+	priv->can.can_stats.bus_error++;
+
+	skb = alloc_can_err_skb(ndev, &cf);
+	if (skb)
+		cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
+
+	switch (bus_err) {
+	case NCT6694_CAN_EVT_ERR_CRC_ERROR:
+		netdev_dbg(ndev, "CRC error\n");
+		ndev->stats.rx_errors++;
+		if (skb)
+			cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ;
+		break;
+
+	case NCT6694_CAN_EVT_ERR_STUFF_ERROR:
+		netdev_dbg(ndev, "Stuff error\n");
+		ndev->stats.rx_errors++;
+		if (skb)
+			cf->data[2] |= CAN_ERR_PROT_STUFF;
+		break;
+
+	case NCT6694_CAN_EVT_ERR_ACK_ERROR:
+		netdev_dbg(ndev, "Ack error\n");
+		ndev->stats.tx_errors++;
+		if (skb) {
+			cf->can_id |= CAN_ERR_ACK;
+			cf->data[2] |= CAN_ERR_PROT_TX;
+		}
+		break;
+
+	case NCT6694_CAN_EVT_ERR_FORM_ERROR:
+		netdev_dbg(ndev, "Form error\n");
+		ndev->stats.rx_errors++;
+		if (skb)
+			cf->data[2] |= CAN_ERR_PROT_FORM;
+		break;
+
+	case NCT6694_CAN_EVT_ERR_BIT_ERROR:
+		netdev_dbg(ndev, "Bit error\n");
+		ndev->stats.tx_errors++;
+		if (skb)
+			cf->data[2] |= CAN_ERR_PROT_TX | CAN_ERR_PROT_BIT;
+		break;
+
+	default:
+		break;
+	}
+
+	nct6694_can_rx_offload(&priv->offload, skb);
+}
+
+static void nct6694_can_tx_irq(struct net_device *ndev)
+{
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+
+	guard(mutex)(&priv->lock);
+	stats->tx_bytes += can_get_echo_skb(ndev, 0, NULL);
+	stats->tx_packets++;
+	netif_wake_queue(ndev);
+}
+
+static irqreturn_t nct6694_can_irq(int irq, void *data)
+{
+	struct net_device *ndev = data;
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+	struct nct6694_can_event *evt = priv->rx->event;
+	struct nct6694_cmd_header cmd_hd;
+	u8 tx_evt, rx_evt, bus_err, can_status;
+	u8 mask_sts = NCT6694_CAN_EVENT_MASK;
+	irqreturn_t handled = IRQ_NONE;
+	int can_idx = priv->can_idx;
+	int ret;
+
+	scoped_guard(mutex, &priv->lock) {
+		cmd_hd = (struct nct6694_cmd_header) {
+			.mod = NCT6694_CAN_MOD,
+			.cmd = NCT6694_CAN_EVENT,
+			.sel = NCT6694_CAN_EVENT_SEL(priv->can_idx, mask_sts),
+			.len = cpu_to_le16(sizeof(priv->rx->event))
+		};
+
+		ret = nct6694_read_msg(priv->nct6694, &cmd_hd, evt);
+		if (ret < 0)
+			return handled;
+
+		tx_evt = evt[can_idx].tx_evt;
+		rx_evt = evt[can_idx].rx_evt;
+		bus_err = evt[can_idx].err;
+		can_status = evt[can_idx].status;
+	}
+
+	if (rx_evt & NCT6694_CAN_EVT_RX_DATA_IN) {
+		nct6694_can_rx(ndev, rx_evt);
+		handled = IRQ_HANDLED;
+	}
+
+	if (rx_evt & NCT6694_CAN_EVT_RX_DATA_LOST) {
+		nct6694_can_handle_lost_msg(ndev);
+		handled = IRQ_HANDLED;
+	}
+
+	if (can_status) {
+		nct6694_can_handle_state_change(ndev, can_status);
+		handled = IRQ_HANDLED;
+	}
+
+	if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING) {
+		nct6694_handle_bus_err(ndev, bus_err);
+		handled = IRQ_HANDLED;
+	}
+
+	if (handled)
+		can_rx_offload_threaded_irq_finish(&priv->offload);
+
+	if (tx_evt & NCT6694_CAN_EVT_TX_FIFO_EMPTY)
+		nct6694_can_tx_irq(ndev);
+
+	return handled;
+}
+
+static void nct6694_can_tx(struct net_device *ndev)
+{
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+	struct nct6694_can_frame *frame = &priv->tx->frame;
+	struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_CAN_MOD,
+		.cmd = NCT6694_CAN_DELIVER,
+		.sel = NCT6694_CAN_DELIVER_SEL(1),
+		.len = cpu_to_le16(sizeof(*frame))
+	};
+	struct net_device_stats *stats = &ndev->stats;
+	struct sk_buff *skb = priv->tx_skb;
+	struct canfd_frame *cfd;
+	struct can_frame *cf;
+	u32 txid;
+	int err;
+
+	memset(frame, 0, sizeof(*frame));
+
+	if (priv->can_idx == 0)
+		frame->tag = NCT6694_CAN_FRAME_TAG_CAN0;
+	else
+		frame->tag = NCT6694_CAN_FRAME_TAG_CAN1;
+
+	if (can_is_canfd_skb(skb)) {
+		cfd = (struct canfd_frame *)priv->tx_skb->data;
+
+		if (cfd->flags & CANFD_BRS)
+			frame->flag |= NCT6694_CAN_FRAME_FLAG_BRS;
+
+		if (cfd->can_id & CAN_EFF_FLAG) {
+			txid = cfd->can_id & CAN_EFF_MASK;
+			frame->flag |= NCT6694_CAN_FRAME_FLAG_EFF;
+		} else {
+			txid = cfd->can_id & CAN_SFF_MASK;
+		}
+		frame->flag |= NCT6694_CAN_FRAME_FLAG_FD;
+		frame->id = cpu_to_le32(txid);
+		frame->length = cfd->len;
+
+		memcpy(frame->data, cfd->data, cfd->len);
+	} else {
+		cf = (struct can_frame *)priv->tx_skb->data;
+
+		if (cf->can_id & CAN_RTR_FLAG)
+			frame->flag |= NCT6694_CAN_FRAME_FLAG_RTR;
+
+		if (cf->can_id & CAN_EFF_FLAG) {
+			txid = cf->can_id & CAN_EFF_MASK;
+			frame->flag |= NCT6694_CAN_FRAME_FLAG_EFF;
+		} else {
+			txid = cf->can_id & CAN_SFF_MASK;
+		}
+		frame->id = cpu_to_le32(txid);
+		frame->length = cf->len;
+
+		memcpy(frame->data, cf->data, cf->len);
+	}
+
+	err = nct6694_write_msg(priv->nct6694, &cmd_hd, frame);
+	if (err) {
+		netdev_err(ndev, "%s: Tx FIFO full!\n", __func__);
+		can_free_echo_skb(ndev, 0, NULL);
+		stats->tx_dropped++;
+		stats->tx_errors++;
+		netif_wake_queue(ndev);
+	}
+}
+
+static void nct6694_can_tx_work(struct work_struct *work)
+{
+	struct nct6694_can_priv *priv = container_of(work,
+						     struct nct6694_can_priv,
+						     tx_work);
+	struct net_device *ndev = priv->ndev;
+
+	guard(mutex)(&priv->lock);
+
+	if (priv->tx_skb) {
+		if (priv->can.state == CAN_STATE_BUS_OFF) {
+			nct6694_can_clean(ndev);
+		} else {
+			nct6694_can_tx(ndev);
+			can_put_echo_skb(priv->tx_skb, ndev, 0, 0);
+			priv->tx_skb = NULL;
+		}
+	}
+}
+
+static netdev_tx_t nct6694_can_start_xmit(struct sk_buff *skb,
+					  struct net_device *ndev)
+{
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+
+	if (can_dev_dropped_skb(ndev, skb))
+		return NETDEV_TX_OK;
+
+	if (priv->tx_skb) {
+		netdev_err(ndev, "hard_xmit called while tx busy\n");
+		return NETDEV_TX_BUSY;
+	}
+
+	netif_stop_queue(ndev);
+	priv->tx_skb = skb;
+	queue_work(priv->wq, &priv->tx_work);
+
+	return NETDEV_TX_OK;
+}
+
+static int nct6694_can_start(struct net_device *ndev)
+{
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+	struct nct6694_can_setting *setting = &priv->tx->setting;
+	struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_CAN_MOD,
+		.cmd = NCT6694_CAN_SETTING,
+		.sel = NCT6694_CAN_SETTING_SEL(priv->can_idx),
+		.len = cpu_to_le16(sizeof(*setting))
+	};
+	const struct can_bittiming *n_bt = &priv->can.bittiming;
+	const struct can_bittiming *d_bt = &priv->can.data_bittiming;
+	int ret;
+
+	guard(mutex)(&priv->lock);
+
+	memset(setting, 0, sizeof(*setting));
+	setting->nbr = cpu_to_le32(n_bt->bitrate);
+	setting->dbr = cpu_to_le32(d_bt->bitrate);
+
+	if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
+		setting->ctrl1 |= cpu_to_le16(NCT6694_CAN_SETTING_CTRL1_MON);
+
+	if ((priv->can.ctrlmode & CAN_CTRLMODE_FD) &&
+	    priv->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)
+		setting->ctrl1 |= cpu_to_le16(NCT6694_CAN_SETTING_CTRL1_NISO);
+
+	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
+		setting->ctrl1 |= cpu_to_le16(NCT6694_CAN_SETTING_CTRL1_LBCK);
+
+	ret = nct6694_write_msg(priv->nct6694, &cmd_hd, setting);
+	if (ret)
+		return ret;
+
+	priv->can.state = CAN_STATE_ERROR_ACTIVE;
+
+	return ret;
+}
+
+static int nct6694_can_stop(struct net_device *ndev)
+{
+	struct nct6694_can_priv *priv = netdev_priv(ndev);
+
+	netif_stop_queue(ndev);
+	free_irq(ndev->irq, ndev);
+	destroy_workqueue(priv->wq);
+	priv->wq = NULL;
+	nct6694_can_clean(ndev);
+	priv->can.state = CAN_STATE_STOPPED;
+	can_rx_offload_disable(&priv->offload);
+	close_candev(ndev);
+
+	return 0;
+}
+
+static int nct6694_can_set_mode(struct net_device *ndev, enum can_mode mode)
+{
+	switch (mode) {
+	case CAN_MODE_START:
+		nct6694_can_clean(ndev);
+		nct6694_can_start(ndev);
+		netif_wake_queue(ndev);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int nct6694_can_open(struct net_device *ndev)
+{
+	struct nct6694_can_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_can_irq, IRQF_ONESHOT,
+				   "nct6694_can", ndev);
+	if (ret) {
+		netdev_err(ndev, "Failed to request IRQ\n");
+		goto close_candev;
+	}
+
+	priv->wq = alloc_ordered_workqueue("%s-nct6694_wq",
+					   WQ_FREEZABLE | WQ_MEM_RECLAIM,
+					   ndev->name);
+	if (!priv->wq) {
+		ret = -ENOMEM;
+		goto free_irq;
+	}
+
+	priv->tx_skb = NULL;
+
+	ret = nct6694_can_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);
+close_candev:
+	can_rx_offload_disable(&priv->offload);
+	close_candev(ndev);
+	return ret;
+}
+
+static const struct net_device_ops nct6694_can_netdev_ops = {
+	.ndo_open = nct6694_can_open,
+	.ndo_stop = nct6694_can_stop,
+	.ndo_start_xmit = nct6694_can_start_xmit,
+	.ndo_change_mtu = can_change_mtu,
+};
+
+static const struct ethtool_ops nct6694_can_ethtool_ops = {
+	.get_ts_info = ethtool_op_get_ts_info,
+};
+
+static int nct6694_can_get_clock(struct nct6694_can_priv *priv)
+{
+	struct nct6694_can_information *info = &priv->rx->info;
+	struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_CAN_MOD,
+		.cmd = NCT6694_CAN_INFORMATION,
+		.sel = NCT6694_CAN_INFORMATION_SEL,
+		.len = cpu_to_le16(sizeof(*info))
+	};
+	int ret;
+
+	ret = nct6694_read_msg(priv->nct6694, &cmd_hd, info);
+	if (ret)
+		return ret;
+
+	return le32_to_cpu(info->can_clk);
+}
+
+static int nct6694_can_probe(struct platform_device *pdev)
+{
+	const struct mfd_cell *cell = mfd_get_cell(pdev);
+	struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
+	struct nct6694_can_priv *priv;
+	struct net_device *ndev;
+	int ret, irq, can_clk;
+
+	irq = irq_create_mapping(nct6694->domain,
+				 NCT6694_IRQ_CAN1 + cell->id);
+	if (!irq)
+		return irq;
+
+	ndev = alloc_candev(sizeof(struct nct6694_can_priv), 1);
+	if (!ndev)
+		return -ENOMEM;
+
+	ndev->irq = irq;
+	ndev->flags |= IFF_ECHO;
+	ndev->netdev_ops = &nct6694_can_netdev_ops;
+	ndev->ethtool_ops = &nct6694_can_ethtool_ops;
+
+	priv = netdev_priv(ndev);
+	priv->nct6694 = nct6694;
+	priv->ndev = ndev;
+
+	priv->tx = devm_kzalloc(&pdev->dev, sizeof(union nct6694_can_tx),
+				GFP_KERNEL);
+	if (!priv->tx) {
+		ret = -ENOMEM;
+		goto free_candev;
+	}
+
+	priv->rx = devm_kzalloc(&pdev->dev, sizeof(union nct6694_can_rx),
+				GFP_KERNEL);
+	if (!priv->rx) {
+		ret = -ENOMEM;
+		goto free_candev;
+	}
+
+	can_clk = nct6694_can_get_clock(priv);
+	if (can_clk < 0) {
+		ret = dev_err_probe(&pdev->dev, can_clk,
+				    "Failed to get clock\n");
+		goto free_candev;
+	}
+
+	devm_mutex_init(&pdev->dev, &priv->lock);
+	INIT_WORK(&priv->tx_work, nct6694_can_tx_work);
+
+	priv->can_idx = cell->id;
+	priv->can.state = CAN_STATE_STOPPED;
+	priv->can.clock.freq = can_clk;
+	priv->can.bittiming_const = &nct6694_can_bittiming_nominal_const;
+	priv->can.data_bittiming_const = &nct6694_can_bittiming_data_const;
+	priv->can.do_set_mode = nct6694_can_set_mode;
+	priv->can.do_get_berr_counter = nct6694_can_get_berr_counter;
+
+	priv->can.ctrlmode = CAN_CTRLMODE_FD;
+
+	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK		|
+				       CAN_CTRLMODE_LISTENONLY		|
+				       CAN_CTRLMODE_FD			|
+				       CAN_CTRLMODE_FD_NON_ISO		|
+				       CAN_CTRLMODE_BERR_REPORTING;
+
+	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 del_rx_offload;
+
+	return 0;
+
+del_rx_offload:
+	can_rx_offload_del(&priv->offload);
+free_candev:
+	free_candev(ndev);
+	return ret;
+}
+
+static void nct6694_can_remove(struct platform_device *pdev)
+{
+	struct nct6694_can_priv *priv = platform_get_drvdata(pdev);
+
+	cancel_work_sync(&priv->tx_work);
+	unregister_candev(priv->ndev);
+	can_rx_offload_del(&priv->offload);
+	free_candev(priv->ndev);
+}
+
+static struct platform_driver nct6694_can_driver = {
+	.driver = {
+		.name	= DRVNAME,
+	},
+	.probe		= nct6694_can_probe,
+	.remove		= nct6694_can_remove,
+};
+
+module_platform_driver(nct6694_can_driver);
+
+MODULE_DESCRIPTION("USB-CAN FD driver for NCT6694");
+MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:nct6694-can");
-- 
2.34.1