Message-Id: <20241024085922.133071-5-tmyu0@nuvoton.com>
Date: Thu, 24 Oct 2024 16:59:17 +0800
From: Ming Yu <a0282524688@...il.com>
To: tmyu0@...oton.com,
	lee@...nel.org,
	linus.walleij@...aro.org,
	brgl@...ev.pl,
	andi.shyti@...nel.org,
	mkl@...gutronix.de,
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	edumazet@...gle.com,
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	pabeni@...hat.com,
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	lars@...afoo.de,
	ukleinek@...nel.org,
	alexandre.belloni@...tlin.com
Cc: linux-kernel@...r.kernel.org,
	linux-gpio@...r.kernel.org,
	linux-i2c@...r.kernel.org,
	linux-can@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-watchdog@...r.kernel.org,
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Subject: [PATCH v1 4/9] can: Add Nuvoton NCT6694 CAN support

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

Signed-off-by: Ming Yu <tmyu0@...oton.com>
---
 MAINTAINERS                     |   1 +
 drivers/net/can/Kconfig         |  10 +
 drivers/net/can/Makefile        |   1 +
 drivers/net/can/nct6694_canfd.c | 843 ++++++++++++++++++++++++++++++++
 4 files changed, 855 insertions(+)
 create mode 100644 drivers/net/can/nct6694_canfd.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 1cc64f9f154a..eccd5e795daa 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16441,6 +16441,7 @@ S:	Supported
 F:	drivers/gpio/gpio-nct6694.c
 F:	drivers/i2c/busses/i2c-nct6694.c
 F:	drivers/mfd/nct6694.c
+F:	drivers/net/can/nct6694_canfd.c
 F:	include/linux/mfd/nct6694.h
 
 NVIDIA (rivafb and nvidiafb) FRAMEBUFFER DRIVER
diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
index cf989bea9aa3..569feda37731 100644
--- a/drivers/net/can/Kconfig
+++ b/drivers/net/can/Kconfig
@@ -200,6 +200,16 @@ config CAN_SUN4I
 	  To compile this driver as a module, choose M here: the module will
 	  be called sun4i_can.
 
+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_TI_HECC
 	depends on ARM
 	tristate "TI High End CAN Controller"
diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
index a71db2cfe990..825c011aead5 100644
--- a/drivers/net/can/Makefile
+++ b/drivers/net/can/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_CAN_JANZ_ICAN3)	+= janz-ican3.o
 obj-$(CONFIG_CAN_KVASER_PCIEFD)	+= kvaser_pciefd.o
 obj-$(CONFIG_CAN_MSCAN)		+= mscan/
 obj-$(CONFIG_CAN_M_CAN)		+= m_can/
+obj-$(CONFIG_CAN_NCT6694)	+= nct6604_canfd.o
 obj-$(CONFIG_CAN_PEAK_PCIEFD)	+= peak_canfd/
 obj-$(CONFIG_CAN_SJA1000)	+= sja1000/
 obj-$(CONFIG_CAN_SUN4I)		+= sun4i_can.o
diff --git a/drivers/net/can/nct6694_canfd.c b/drivers/net/can/nct6694_canfd.c
new file mode 100644
index 000000000000..d873a9fd656d
--- /dev/null
+++ b/drivers/net/can/nct6694_canfd.c
@@ -0,0 +1,843 @@
+// 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/kernel.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/mfd/core.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/nct6694.h>
+
+#define DRVNAME "nct6694-can"
+
+#define RX_QUATA        64
+
+/* Host interface */
+#define REQUEST_CAN_MOD			0x05
+
+/* Message Channel*/
+/* Command 00h */
+#define REQUEST_CAN_CMD0_LEN		0x18
+#define REQUEST_CAN_CMD0_OFFSET(idx)	(idx ? 0x0100 : 0x0000)
+#define CAN_NBR_IDX			0x00
+#define CAN_DBR_IDX			0x04
+#define CAN_CTRL1_IDX			0x0C
+#define CAN_CTRL1_MON			BIT(0)
+#define CAN_CTRL1_NISO			BIT(1)
+#define CAN_CTRL1_LBCK			BIT(2)
+
+/* Command 01h */
+#define REQUEST_CAN_CMD1_LEN		0x08
+#define REQUEST_CAN_CMD1_OFFSET		0x0001
+#define CAN_CLK_IDX			0x04
+#define CAN_CLK_LEN			0x04
+
+/* Command 02h */
+#define REQUEST_CAN_CMD2_LEN            0x10
+#define REQUEST_CAN_CMD2_OFFSET(idx, mask)			\
+	({ typeof(mask) mask_ = (mask);				\
+	   idx ? ((0x80 | (mask_ & 0xFF)) << 8 | 0x02) :	\
+		 ((0x00 | (mask_ & 0xFF)) << 8 | 0x02); })
+
+#define CAN_ERR_IDX(idx)		(idx ? 0x08 : 0x00)	/* Read-clear */
+#define CAN_STATUS_IDX(idx)		(idx ? 0x09 : 0x01)
+#define CAN_TX_EVT_IDX(idx)		(idx ? 0x0A : 0x02)
+#define CAN_RX_EVT_IDX(idx)		(idx ? 0x0B : 0x03)
+#define CAN_REC_IDX(idx)		(idx ? 0x0C : 0x04)
+#define CAN_TEC_IDX(idx)		(idx ? 0x0D : 0x05)
+#define CAN_EVENT_ERR			BIT(0)
+#define CAN_EVENT_STATUS		BIT(1)
+#define CAN_EVENT_TX_EVT		BIT(2)
+#define CAN_EVENT_RX_EVT		BIT(3)
+#define CAN_EVENT_REC			BIT(4)
+#define CAN_EVENT_TEC			BIT(5)
+#define CAN_EVENT_ERR_NO_ERROR		0x00	/* Read-clear */
+#define CAN_EVENT_ERR_CRC_ERROR		0x01	/* Read-clear */
+#define CAN_EVENT_ERR_STUFF_ERROR	0x02	/* Read-clear */
+#define CAN_EVENT_ERR_ACK_ERROR		0x03	/* Read-clear */
+#define CAN_EVENT_ERR_FORM_ERROR	0x04	/* Read-clear */
+#define CAN_EVENT_ERR_BIT_ERROR		0x05	/* Read-clear */
+#define CAN_EVENT_ERR_TIMEOUT_ERROR	0x06	/* Read-clear */
+#define CAN_EVENT_ERR_UNKNOWN_ERROR	0x07	/* Read-clear */
+#define CAN_EVENT_STATUS_ERROR_ACTIVE	0x00
+#define CAN_EVENT_STATUS_ERROR_PASSIVE	0x01
+#define CAN_EVENT_STATUS_BUS_OFF	0x02
+#define CAN_EVENT_STATUS_WARNING	0x03
+#define CAN_EVENT_TX_EVT_TX_FIFO_EMPTY	BIT(7)	/* Read-clear */
+#define CAN_EVENT_RX_EVT_DATA_LOST	BIT(5)	/* Read-clear */
+#define CAN_EVENT_RX_EVT_HALF_FULL	BIT(6)	/* Read-clear */
+#define CAN_EVENT_RX_EVT_DATA_IN	BIT(7)
+
+/* Command 10h */
+#define REQUEST_CAN_CMD10_LEN		0x90
+#define REQUEST_CAN_CMD10_OFFSET(buf_cnt)	\
+	(((buf_cnt) & 0xFF) << 8 | 0x10)
+#define CAN_TAG_IDX			0x00
+#define CAN_FLAG_IDX			0x01
+#define CAN_DLC_IDX			0x03
+#define CAN_ID_IDX			0x04
+#define CAN_DATA_IDX			0x08
+#define CAN_TAG_CAN0			0xC0
+#define CAN_TAG_CAN1			0xC1
+#define CAN_FLAG_EFF			BIT(0)
+#define CAN_FLAG_RTR			BIT(1)
+#define CAN_FLAG_FD			BIT(2)
+#define CAN_FLAG_BRS			BIT(3)
+#define CAN_FLAG_ERR			BIT(4)
+
+/* Command 11h */
+#define REQUEST_CAN_CMD11_LEN		0x90
+#define REQUEST_CAN_CMD11_OFFSET(idx, buf_cnt)			\
+	({ typeof(buf_cnt) buf_cnt_ = (buf_cnt);		\
+	   idx ? ((0x80 | (buf_cnt_ & 0xFF)) << 8 | 0x11) :	\
+		 ((0x00 | (buf_cnt_ & 0xFF)) << 8 | 0x11); })
+
+struct nct6694_canfd_priv {
+	struct can_priv can;	/* must be the first member */
+
+	struct nct6694 *nct6694;
+	struct net_device *ndev;
+	struct work_struct rx_work;
+	struct work_struct tx_work;
+	unsigned char data_buf[REQUEST_CAN_CMD10_LEN];
+	unsigned char can_idx;
+};
+
+static inline void set_buf16(void *buf, u16 u16_val)
+{
+	u8 *p = (u8 *)buf;
+
+	p[0] = u16_val & 0xFF;
+	p[1] = (u16_val >> 8) & 0xFF;
+}
+
+static inline void set_buf32(void *buf, u32 u32_val)
+{
+	u8 *p = (u8 *)buf;
+
+	p[0] = u32_val & 0xFF;
+	p[1] = (u32_val >> 8) & 0xFF;
+	p[2] = (u32_val >> 16) & 0xFF;
+	p[3] = (u32_val >> 24) & 0xFF;
+}
+
+static const struct can_bittiming_const nct6694_canfd_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_canfd_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_canfd_set_bittiming(struct net_device *ndev,
+					unsigned char *buf)
+{
+	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.data_bittiming;
+
+	set_buf32(&buf[CAN_NBR_IDX], n_bt->bitrate);
+	set_buf32(&buf[CAN_DBR_IDX], d_bt->bitrate);
+
+	pr_info("%s: can(%d): NBR = %d, DBR = %d\n", __func__, priv->can_idx,
+		n_bt->bitrate, d_bt->bitrate);
+}
+
+static int nct6694_canfd_start(struct net_device *ndev)
+{
+	int ret;
+	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
+	unsigned char buf[REQUEST_CAN_CMD0_LEN] = {0};
+	u16 temp = 0;
+
+	nct6694_canfd_set_bittiming(ndev, buf);
+
+	if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
+		temp |= CAN_CTRL1_MON;
+
+	if ((priv->can.ctrlmode & CAN_CTRLMODE_FD) &&
+	    priv->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)
+		temp |= CAN_CTRL1_NISO;
+
+	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
+		temp |= CAN_CTRL1_LBCK;
+
+	set_buf16(&buf[CAN_CTRL1_IDX], temp);
+
+	ret = nct6694_write_msg(priv->nct6694, REQUEST_CAN_MOD,
+				REQUEST_CAN_CMD0_OFFSET(priv->can_idx),
+				REQUEST_CAN_CMD0_LEN, buf);
+	if (ret < 0) {
+		pr_err("%s: Failed to set data bittiming\n", __func__);
+		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);
+
+	priv->can.state = CAN_STATE_STOPPED;
+}
+
+static int nct6694_canfd_set_mode(struct net_device *ndev, enum can_mode mode)
+{
+	switch (mode) {
+	case CAN_MODE_START:
+		nct6694_canfd_start(ndev);
+		netif_wake_queue(ndev);
+		break;
+
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+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);
+	unsigned char mask = CAN_EVENT_REC | CAN_EVENT_TEC;
+	unsigned char buf[REQUEST_CAN_CMD2_LEN] = {0};
+	int ret;
+
+	ret = nct6694_read_msg(priv->nct6694, REQUEST_CAN_MOD,
+			       REQUEST_CAN_CMD2_OFFSET(priv->can_idx, mask),
+			       REQUEST_CAN_CMD2_LEN, 0x00,
+			       REQUEST_CAN_CMD2_LEN, (unsigned char *)&buf);
+	if (ret < 0)
+		return -EINVAL;
+
+	bec->rxerr = buf[CAN_REC_IDX(priv->can_idx)];
+	bec->txerr = buf[CAN_TEC_IDX(priv->can_idx)];
+
+	return 0;
+}
+
+static int nct6694_canfd_open(struct net_device *ndev)
+{
+	int ret;
+
+	ret = open_candev(ndev);
+	if (ret)
+		return ret;
+
+	ret = nct6694_canfd_start(ndev);
+	if (ret) {
+		close_candev(ndev);
+		return ret;
+	}
+
+	netif_start_queue(ndev);
+
+	return 0;
+}
+
+static int nct6694_canfd_close(struct net_device *ndev)
+{
+	netif_stop_queue(ndev);
+	nct6694_canfd_stop(ndev);
+	close_candev(ndev);
+
+	return 0;
+}
+
+static netdev_tx_t nct6694_canfd_start_xmit(struct sk_buff *skb,
+					    struct net_device *ndev)
+{
+	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
+	struct nct6694 *nct6694 = priv->nct6694;
+	struct canfd_frame *cf = (struct canfd_frame *)skb->data;
+	struct net_device_stats *stats = &ndev->stats;
+	int can_idx = priv->can_idx;
+	u32 txid = 0;
+	int i;
+	unsigned int echo_byte;
+	u8 data_buf[REQUEST_CAN_CMD10_LEN] = {0};
+
+	if (can_dropped_invalid_skb(ndev, skb))
+		return NETDEV_TX_OK;
+
+	/*
+	 * No check for NCT66794 because the TX bit is read-clear
+	 * and may be read-cleared by other function
+	 * Just check the result of tx command.
+	 */
+	/* Check if the TX buffer is full */
+	netif_stop_queue(ndev);
+
+	if (can_idx == 0)
+		data_buf[CAN_TAG_IDX] = CAN_TAG_CAN0;
+	else
+		data_buf[CAN_TAG_IDX] = CAN_TAG_CAN1;
+
+	if (cf->can_id & CAN_EFF_FLAG) {
+		txid = cf->can_id & CAN_EFF_MASK;
+		/*
+		 * In case the Extended ID frame is transmitted, the
+		 * standard and extended part of the ID are swapped
+		 * in the register, so swap them back to send the
+		 * correct ID.
+		 */
+		data_buf[CAN_FLAG_IDX] |= CAN_FLAG_EFF;
+	} else {
+		txid = cf->can_id & CAN_SFF_MASK;
+	}
+
+	set_buf32(&data_buf[CAN_ID_IDX], txid);
+
+	data_buf[CAN_DLC_IDX] = cf->len;
+
+	if ((priv->can.ctrlmode & CAN_CTRLMODE_FD) && can_is_canfd_skb(skb)) {
+		data_buf[CAN_FLAG_IDX] |= CAN_FLAG_FD;
+		if (cf->flags & CANFD_BRS)
+			data_buf[CAN_FLAG_IDX] |= CAN_FLAG_BRS;
+	}
+
+	if (cf->can_id & CAN_RTR_FLAG)
+		data_buf[CAN_FLAG_IDX] |= CAN_FLAG_RTR;
+
+	/* set data to buf */
+	for (i = 0; i < cf->len; i++)
+		data_buf[CAN_DATA_IDX + i] = *(u8 *)(cf->data + i);
+
+	can_put_echo_skb(skb, ndev, 0, 0);
+
+	memcpy(priv->data_buf, data_buf, REQUEST_CAN_CMD10_LEN);
+	queue_work(nct6694->async_workqueue, &priv->tx_work);
+
+	stats->tx_bytes += cf->len;
+	stats->tx_packets++;
+	echo_byte = can_get_echo_skb(ndev, 0, NULL);
+
+	netif_wake_queue(ndev);
+
+	return NETDEV_TX_OK;
+}
+
+static void nct6694_canfd_tx_work(struct work_struct *work)
+{
+	struct nct6694_canfd_priv *priv;
+
+	priv = container_of(work, struct nct6694_canfd_priv, tx_work);
+
+	nct6694_write_msg(priv->nct6694, REQUEST_CAN_MOD,
+			  REQUEST_CAN_CMD10_OFFSET(1),
+			  REQUEST_CAN_CMD10_LEN,
+			  priv->data_buf);
+}
+
+static int nuv_canfd_handle_lost_msg(struct net_device *ndev)
+{
+	struct net_device_stats *stats = &ndev->stats;
+	struct sk_buff *skb;
+	struct can_frame *frame;
+
+	netdev_err(ndev, "RX FIFO overflow, message(s) lost.\n");
+
+	stats->rx_errors++;
+	stats->rx_over_errors++;
+
+	skb = alloc_can_err_skb(ndev, &frame);
+	if (unlikely(!skb))
+		return 0;
+
+	pr_info("%s: CAN_ERR_CRTL_RX_OVERFLOW\r\n", __func__);
+
+	frame->can_id |= CAN_ERR_CRTL;
+	frame->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+
+	netif_receive_skb(skb);
+
+	return 1;
+}
+
+static void nuv_canfd_read_fifo(struct net_device *ndev)
+{
+	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+	struct canfd_frame *cf;
+	struct sk_buff *skb;
+	int can_idx = priv->can_idx;
+	u32 id;
+	int ret;
+	u8 data_buf[REQUEST_CAN_CMD11_LEN] = {0};
+	u8 fd_format = 0;
+	int i;
+
+	ret = nct6694_read_msg(priv->nct6694, REQUEST_CAN_MOD,
+			       REQUEST_CAN_CMD11_OFFSET(can_idx, 1),
+			       REQUEST_CAN_CMD11_LEN, 0, REQUEST_CAN_CMD11_LEN,
+			       data_buf);
+	if (ret < 0)
+		return;
+
+	/* Check type of frame and create skb */
+	fd_format = data_buf[CAN_FLAG_IDX] & CAN_FLAG_FD;
+	if (fd_format)
+		skb = alloc_canfd_skb(ndev, &cf);
+	else
+		skb = alloc_can_skb(ndev, (struct can_frame **)&cf);
+
+	if (!skb) {
+		stats->rx_dropped++;
+		return;
+	}
+
+	cf->len = data_buf[CAN_DLC_IDX];
+
+	/* Get ID and set flag by its type(Standard ID format or Ext ID format) */
+	id = le32_to_cpu(*(u32 *)(&data_buf[CAN_ID_IDX]));
+	if (data_buf[CAN_FLAG_IDX] & CAN_FLAG_EFF) {
+		/*
+		 * In case the Extended ID frame is received, the standard
+		 * and extended part of the ID are swapped in the register,
+		 * so swap them back to obtain the correct ID.
+		 */
+		id |= CAN_EFF_FLAG;
+	}
+
+	cf->can_id = id;
+
+	/* Set ESI flag */
+	if (data_buf[CAN_FLAG_IDX] & CAN_FLAG_ERR) {
+		cf->flags |= CANFD_ESI;
+		netdev_dbg(ndev, "ESI Error\n");
+	}
+
+	/* Set RTR and BRS */
+	if (!fd_format && (data_buf[CAN_FLAG_IDX] & CAN_FLAG_RTR)) {
+		cf->can_id |= CAN_RTR_FLAG;
+	} else {
+		if (data_buf[CAN_FLAG_IDX] & CAN_FLAG_BRS)
+			cf->flags |= CANFD_BRS;
+
+		for (i = 0; i < cf->len; i++)
+			*(u8 *)(cf->data + i) = data_buf[CAN_DATA_IDX + i];
+	}
+
+	/* Remove the packet from FIFO */
+	stats->rx_packets++;
+	stats->rx_bytes += cf->len;
+	netif_receive_skb(skb);
+}
+
+static int nct6694_canfd_do_rx_poll(struct net_device *ndev, int quota)
+{
+	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
+	int can_idx = priv->can_idx;
+	u32 pkts = 0;
+	u8 data_buf_can_evt[REQUEST_CAN_CMD2_LEN] = {0};
+	u8 mask_rx = CAN_EVENT_RX_EVT;
+	u8 rx_evt;
+
+	for (;;) {
+		nct6694_read_msg(priv->nct6694, REQUEST_CAN_MOD,
+				 REQUEST_CAN_CMD2_OFFSET(can_idx, mask_rx),
+				 REQUEST_CAN_CMD2_LEN, 0,
+				 REQUEST_CAN_CMD2_LEN, data_buf_can_evt);
+
+		/* Handle lost messages when handling RX because it is read-cleared reg */
+		rx_evt = data_buf_can_evt[CAN_RX_EVT_IDX(can_idx)];
+		if (rx_evt & CAN_EVENT_RX_EVT_DATA_LOST)
+			nuv_canfd_handle_lost_msg(ndev);
+
+		/* No data */
+		if ((rx_evt & CAN_EVENT_RX_EVT_DATA_IN) == 0)
+			break;
+
+		if (quota <= 0)
+			break;
+
+		nuv_canfd_read_fifo(ndev);
+		quota--;
+		pkts++;
+	}
+
+	return pkts;
+}
+
+static int nct6694_canfd_handle_lec_err(struct net_device *ndev, u8 bus_err)
+{
+	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+	struct can_frame *cf;
+	struct sk_buff *skb;
+
+	if (bus_err == CAN_EVENT_ERR_NO_ERROR)
+		return 0;
+
+	priv->can.can_stats.bus_error++;
+	stats->rx_errors++;
+
+	/* Propagate the error condition to the CAN stack. */
+	skb = alloc_can_err_skb(ndev, &cf);
+
+	if (unlikely(!skb))
+		return 0;
+
+	/* Read the error counter register and check for new errors. */
+	cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
+
+	switch (bus_err) {
+	case CAN_EVENT_ERR_CRC_ERROR:
+		cf->data[3] = CAN_ERR_PROT_LOC_CRC_SEQ;
+		break;
+
+	case CAN_EVENT_ERR_STUFF_ERROR:
+		cf->data[2] |= CAN_ERR_PROT_STUFF;
+		break;
+
+	case CAN_EVENT_ERR_ACK_ERROR:
+		cf->data[3] = CAN_ERR_PROT_LOC_ACK;
+		break;
+
+	case CAN_EVENT_ERR_FORM_ERROR:
+		cf->data[2] |= CAN_ERR_PROT_FORM;
+		break;
+
+	case CAN_EVENT_ERR_BIT_ERROR:
+		cf->data[2] |= CAN_ERR_PROT_BIT |
+			       CAN_ERR_PROT_BIT0 |
+			       CAN_ERR_PROT_BIT1;
+		break;
+
+	case CAN_EVENT_ERR_TIMEOUT_ERROR:
+		cf->data[2] |= CAN_ERR_PROT_UNSPEC;
+		break;
+
+	case CAN_EVENT_ERR_UNKNOWN_ERROR:
+		cf->data[2] |= CAN_ERR_PROT_UNSPEC;
+		/*
+		 * It means 'unspecified'(the value is '0').
+		 * But it is not sure if it's ok to send an error package
+		 * without specific error bit.
+		 */
+		break;
+
+	default:
+		break;
+	}
+
+	/* Reset the error counter, ack the IRQ and re-enable the counter. */
+	stats->rx_packets++;
+	stats->rx_bytes += cf->can_dlc;
+	netif_receive_skb(skb);
+
+	return 1;
+}
+
+static int nct6694_canfd_handle_state_change(struct net_device *ndev,
+					     enum can_state new_state)
+{
+	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+	struct can_frame *cf;
+	struct sk_buff *skb;
+	struct can_berr_counter bec;
+
+	switch (new_state) {
+	case CAN_STATE_ERROR_ACTIVE:
+		/* error active state */
+		priv->can.can_stats.error_warning++;
+		priv->can.state = CAN_STATE_ERROR_ACTIVE;
+		break;
+	case CAN_STATE_ERROR_WARNING:
+		/* error warning state */
+		priv->can.can_stats.error_warning++;
+		priv->can.state = CAN_STATE_ERROR_WARNING;
+		break;
+	case CAN_STATE_ERROR_PASSIVE:
+		/* error passive state */
+		priv->can.can_stats.error_passive++;
+		priv->can.state = CAN_STATE_ERROR_PASSIVE;
+		break;
+	case CAN_STATE_BUS_OFF:
+		/* bus-off state */
+		priv->can.state = CAN_STATE_BUS_OFF;
+		priv->can.can_stats.bus_off++;
+		can_bus_off(ndev);
+		break;
+	default:
+		break;
+	}
+
+	/* propagate the error condition to the CAN stack */
+	skb = alloc_can_err_skb(ndev, &cf);
+	if (unlikely(!skb))
+		return 0;
+
+	nct6694_canfd_get_berr_counter(ndev, &bec);
+
+	switch (new_state) {
+	case CAN_STATE_ERROR_WARNING:
+		/* error warning state */
+		cf->can_id |= CAN_ERR_CRTL;
+		cf->data[1] = (bec.txerr > bec.rxerr) ? CAN_ERR_CRTL_TX_WARNING :
+							CAN_ERR_CRTL_RX_WARNING;
+		cf->data[6] = bec.txerr;
+		cf->data[7] = bec.rxerr;
+		break;
+	case CAN_STATE_ERROR_PASSIVE:
+		/* error passive state */
+		cf->can_id |= CAN_ERR_CRTL;
+		cf->data[1] |= CAN_ERR_CRTL_RX_PASSIVE;
+		if (bec.txerr > 127)
+			cf->data[1] |= CAN_ERR_CRTL_TX_PASSIVE;
+		cf->data[6] = bec.txerr;
+		cf->data[7] = bec.rxerr;
+		break;
+	case CAN_STATE_BUS_OFF:
+		/* bus-off state */
+		cf->can_id |= CAN_ERR_BUSOFF;
+		break;
+	default:
+		break;
+	}
+
+	stats->rx_packets++;
+	stats->rx_bytes += cf->can_dlc;
+	netif_receive_skb(skb);
+
+	return 1;
+}
+
+static int nct6694_canfd_handle_state_errors(struct net_device *ndev,
+					     u8 *can_evt_buf)
+{
+	struct nct6694_canfd_priv *priv = netdev_priv(ndev);
+	int can_idx = priv->can_idx;
+	int work_done = 0;
+	u8 can_status;
+
+	can_status = can_evt_buf[CAN_STATUS_IDX(can_idx)];
+
+	if (can_status == CAN_EVENT_STATUS_ERROR_ACTIVE &&
+	    priv->can.state != CAN_STATE_ERROR_ACTIVE) {
+		netdev_dbg(ndev, "Error, entered active state\n");
+		work_done += nct6694_canfd_handle_state_change(ndev,
+							       CAN_STATE_ERROR_ACTIVE);
+	}
+
+	if (can_status == CAN_EVENT_STATUS_WARNING &&
+	    priv->can.state != CAN_STATE_ERROR_WARNING) {
+		netdev_dbg(ndev, "Error, entered warning state\n");
+		work_done += nct6694_canfd_handle_state_change(ndev,
+							       CAN_STATE_ERROR_WARNING);
+	}
+
+	if (can_status == CAN_EVENT_STATUS_ERROR_PASSIVE &&
+	    priv->can.state != CAN_STATE_ERROR_PASSIVE) {
+		netdev_dbg(ndev, "Error, entered passive state\n");
+		work_done += nct6694_canfd_handle_state_change(ndev,
+							       CAN_STATE_ERROR_PASSIVE);
+	}
+
+	if (can_status == CAN_EVENT_STATUS_BUS_OFF &&
+	    priv->can.state != CAN_STATE_BUS_OFF) {
+		netdev_dbg(ndev, "Error, entered bus-off state\n");
+		work_done += nct6694_canfd_handle_state_change(ndev,
+							       CAN_STATE_BUS_OFF);
+	}
+
+	return work_done;
+}
+
+static void nct6694_canfd_rx_work(struct work_struct *work)
+{
+	struct nct6694_canfd_priv *priv;
+	struct net_device *ndev;
+	struct net_device_stats *stats;
+	int ret, can_idx;
+	int work_done = 0;
+	int quota = RX_QUATA;
+	u8 data_buf_can_evt[REQUEST_CAN_CMD2_LEN] = {0};
+	u8 bus_err;
+	u8 mask_sts = CAN_EVENT_ERR | CAN_EVENT_STATUS;
+
+	priv = container_of(work, struct nct6694_canfd_priv, rx_work);
+	ndev = priv->ndev;
+	can_idx = priv->can_idx;
+	stats = &ndev->stats;
+
+	ret = nct6694_read_msg(priv->nct6694, REQUEST_CAN_MOD,
+			       REQUEST_CAN_CMD2_OFFSET(can_idx, mask_sts),
+			       REQUEST_CAN_CMD2_LEN, 0, REQUEST_CAN_CMD2_LEN,
+			       data_buf_can_evt);
+	if (ret < 0)
+		return;
+
+	/* Handle bus state changes */
+	work_done += nct6694_canfd_handle_state_errors(ndev, data_buf_can_evt);
+
+	/* Handle lec errors on the bus */
+	if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING) {
+		bus_err = data_buf_can_evt[CAN_ERR_IDX(can_idx)];
+		work_done += nct6694_canfd_handle_lec_err(ndev, bus_err);
+	}
+
+	/*
+	 * Check data lost and handle normal messages on RX.
+	 * Don't check rx fifo-empty here because the data-lost bit in the same reg is read-cleared,
+	 * we handle it when handling rx event
+	 */
+
+	work_done += nct6694_canfd_do_rx_poll(ndev, quota - work_done);
+}
+
+static void nct6694_can_handler(void *private_data)
+{
+	struct nct6694_canfd_priv *priv = private_data;
+	struct nct6694 *nct6694 = priv->nct6694;
+
+	queue_work(nct6694->async_workqueue, &priv->rx_work);
+}
+
+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 int nct6694_canfd_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_canfd_priv *priv;
+	struct net_device *ndev;
+	unsigned int can_clk;
+	int ret;
+
+	ret = nct6694_read_msg(nct6694, REQUEST_CAN_MOD,
+			       REQUEST_CAN_CMD1_OFFSET,
+			       REQUEST_CAN_CMD1_LEN,
+			       CAN_CLK_IDX, CAN_CLK_LEN,
+			       (unsigned char *)&can_clk);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "%s: Failed to get can clock frequency: %pe\n",
+			__func__, ERR_PTR(ret));
+		return ret;
+	}
+
+	pr_info("can_clk = %d\n", le32_to_cpu(can_clk));
+
+	ndev = alloc_candev(sizeof(struct nct6694_canfd_priv), 1);
+	if (!ndev)
+		return -ENOMEM;
+
+	ndev->flags |= IFF_ECHO;
+	ndev->netdev_ops = &nct6694_canfd_netdev_ops;
+
+	priv = netdev_priv(ndev);
+	priv->nct6694 = nct6694;
+	priv->ndev = ndev;
+
+	ret = nct6694_register_handler(nct6694, CAN_IRQ_STATUS,
+				       nct6694_can_handler, priv);
+	if (ret) {
+		dev_err(&pdev->dev, "%s:  Failed to register handler: %pe\n",
+			__func__, ERR_PTR(ret));
+		free_candev(ndev);
+		return ret;
+	}
+
+	INIT_WORK(&priv->rx_work, nct6694_canfd_rx_work);
+	INIT_WORK(&priv->tx_work, nct6694_canfd_tx_work);
+
+	priv->can_idx = cell->id;
+	priv->can.state = CAN_STATE_STOPPED;
+	priv->can.clock.freq = le32_to_cpu(can_clk);
+	priv->can.bittiming_const = &nct6694_canfd_bittiming_nominal_const;
+	priv->can.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 = 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;
+
+	platform_set_drvdata(pdev, priv);
+	SET_NETDEV_DEV(priv->ndev, &pdev->dev);
+
+	ret = register_candev(priv->ndev);
+	if (ret) {
+		dev_err(&pdev->dev, "register_candev failed: %d\n", ret);
+		free_candev(ndev);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void nct6694_canfd_remove(struct platform_device *pdev)
+{
+	struct nct6694_canfd_priv *priv = platform_get_drvdata(pdev);
+
+	cancel_work_sync(&priv->rx_work);
+	unregister_candev(priv->ndev);
+	free_candev(priv->ndev);
+}
+
+static struct platform_driver nct6694_canfd_driver = {
+	.driver = {
+		.name	= DRVNAME,
+	},
+	.probe		= nct6694_canfd_probe,
+	.remove		= nct6694_canfd_remove,
+};
+
+static int __init nct6694_init(void)
+{
+	int err;
+
+	err = platform_driver_register(&nct6694_canfd_driver);
+	if (!err) {
+		if (err)
+			platform_driver_unregister(&nct6694_canfd_driver);
+	}
+
+	return err;
+}
+subsys_initcall(nct6694_init);
+
+static void __exit nct6694_exit(void)
+{
+	platform_driver_unregister(&nct6694_canfd_driver);
+}
+module_exit(nct6694_exit);
+
+MODULE_DESCRIPTION("USB-CAN FD driver for NCT6694");
+MODULE_AUTHOR("Ming Yu <tmyu0@...oton.com>");
+MODULE_LICENSE("GPL");
-- 
2.34.1

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