Date:   Fri, 17 Mar 2023 14:15:53 +0100
From:   Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
To:     "Ji-Ze Hong (Peter Hong)" <peter_hong@fintek.com.tw>
Cc:     wg@grandegger.com, mkl@pengutronix.de, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
        mailhol.vincent@wanadoo.fr, frank.jungclaus@esd.eu,
        linux-kernel@vger.kernel.org, linux-can@vger.kernel.org,
        netdev@vger.kernel.org, hpeter+linux_kernel@gmail.com
Subject: Re: [PATCH] can: usb: f81604: add Fintek F81604 support
Message-ID: <ZBRoCVHV3S3ugEoO@localhost.localdomain>
References: <20230317093352.3979-1-peter_hong@fintek.com.tw>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
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In-Reply-To: <20230317093352.3979-1-peter_hong@fintek.com.tw>
Precedence: bulk

On Fri, Mar 17, 2023 at 05:33:52PM +0800, Ji-Ze Hong (Peter Hong) wrote:
> This patch add support for Fintek USB to 2CAN controller support.
> 
> Signed-off-by: Ji-Ze Hong (Peter Hong) <peter_hong@fintek.com.tw>
> ---
>  drivers/net/can/usb/Kconfig  |    9 +
>  drivers/net/can/usb/Makefile |    1 +
>  drivers/net/can/usb/f81604.c | 1215 ++++++++++++++++++++++++++++++++++
>  3 files changed, 1225 insertions(+)
>  create mode 100644 drivers/net/can/usb/f81604.c
> 
> diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
> index 445504ababce..381547939c39 100644
> --- a/drivers/net/can/usb/Kconfig
> +++ b/drivers/net/can/usb/Kconfig
> @@ -147,4 +147,13 @@ config CAN_UCAN
>  	          from Theobroma Systems like the A31-ÂľQ7 and the RK3399-Q7
>  	          (https://www.theobroma-systems.com/rk3399-q7)
>  
Hi,

I am not familiar with CAN, so only style review :)

> +config CAN_F81604
> +	tristate "Fintek F81604 USB to 2CAN interface"
> +	help
> +	  This driver supports the Fintek F81604 USB to 2CAN interface.
> +	  The device can support CAN2.0A/B protocol and also support
> +	  2 output pins to control external terminator (optional).
> +
> +	  (see also https://www.fintek.com.tw).
> +
>  endmenu
> diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
> index 1ea16be5743b..9de0305a5cce 100644
> --- a/drivers/net/can/usb/Makefile
> +++ b/drivers/net/can/usb/Makefile
> @@ -12,3 +12,4 @@ obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb/
>  obj-$(CONFIG_CAN_MCBA_USB) += mcba_usb.o
>  obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
>  obj-$(CONFIG_CAN_UCAN) += ucan.o
> +obj-$(CONFIG_CAN_F81604) += f81604.o
> diff --git a/drivers/net/can/usb/f81604.c b/drivers/net/can/usb/f81604.c
> new file mode 100644
> index 000000000000..166f5789247e
> --- /dev/null
> +++ b/drivers/net/can/usb/f81604.c
> @@ -0,0 +1,1215 @@
> +// 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/netdevice.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>
> +
> +/* vendor and product id */
> +#define F81604_VENDOR_ID 0x2c42
> +#define F81604_PRODUCT_ID 0x1709
> +#define F81604_MAX_DEV 2
> +
> +#define F81604_USB_MAX_RETRY 10
> +#define F81604_USB_TIMEOUT 2000
> +#define F81604_SET_GET_REGISTER 0xA0
> +#define F81604_PORT_OFFSET 0x1000
> +
> +#define F81604_BULK_SIZE 64
> +#define F81604_INT_SIZE 16
> +#define F81604_DATA_SIZE 14
> +#define F81604_MAX_RX_URBS 4
> +
> +#define F81604_CMD_OFFSET 0x00
> +#define F81604_CMD_DATA 0x00
> +
> +#define F81604_DLC_OFFSET 0x01
> +#define F81604_LEN_MASK 0x0f
> +#define F81604_EFF_BIT BIT(7)
> +#define F81604_RTR_BIT BIT(6)
> +
> +#define F81604_ID1_OFFSET 0x02
> +#define F81604_ID2_OFFSET 0x03
> +#define F81604_ID3_OFFSET 0x04
> +#define F81604_ID4_OFFSET 0x05
> +
> +#define F81604_SFF_DATA_OFFSET 0x04
> +#define F81604_EFF_DATA_OFFSET 0x06
> +
> +/* device setting */
> +#define F81604_TX_ONESHOT (0x03 << 3)
> +#define F81604_TX_NORMAL (0x01 << 3)
> +#define F81604_RX_AUTO_RELEASE_BUF (0x01 << 1)
> +#define F81604_INT_WHEN_CHANGE (0x01 << 0)
> +
> +/* SJA1000 registers - manual section 6.4 (Pelican Mode) */
> +#define SJA1000_MOD 0x00
> +#define SJA1000_CMR 0x01
> +#define SJA1000_IR 0x03
> +#define SJA1000_IER 0x04
> +#define SJA1000_ALC 0x0B
> +#define SJA1000_ECC 0x0C
> +#define SJA1000_RXERR 0x0E
> +#define SJA1000_TXERR 0x0F
> +#define SJA1000_ACCC0 0x10
> +#define SJA1000_ACCC1 0x11
> +#define SJA1000_ACCC2 0x12
> +#define SJA1000_ACCC3 0x13
> +#define SJA1000_ACCM0 0x14
> +#define SJA1000_ACCM1 0x15
> +#define SJA1000_ACCM2 0x16
> +#define SJA1000_ACCM3 0x17
> +
> +/* Common registers - manual section 6.5 */
> +#define SJA1000_BTR0 0x06
> +#define SJA1000_BTR1 0x07
> +#define SJA1000_OCR 0x08
> +#define SJA1000_CDR 0x1F
> +
> +#define SJA1000_FI 0x10
> +#define SJA1000_SFF_BUF 0x13
> +#define SJA1000_EFF_BUF 0x15
> +
> +#define SJA1000_FI_FF 0x80
> +#define SJA1000_FI_RTR 0x40
> +
> +#define SJA1000_ID1 0x11
> +#define SJA1000_ID2 0x12
> +#define SJA1000_ID3 0x13
> +#define SJA1000_ID4 0x14
> +
> +/* mode register */
> +#define MOD_RM 0x01
> +#define MOD_LOM 0x02
> +#define MOD_STM 0x04
> +
> +/* commands */
> +#define CMD_CDO 0x08
> +
> +/* interrupt sources */
> +#define IRQ_BEI 0x80
> +#define IRQ_ALI 0x40
> +#define IRQ_EPI 0x20
> +#define IRQ_DOI 0x08
> +#define IRQ_EI 0x04
> +#define IRQ_TI 0x02
> +#define IRQ_RI 0x01
> +#define IRQ_ALL 0xFF
> +#define IRQ_OFF 0x00
> +
> +/* status register content */
> +#define SR_BS 0x80
> +#define SR_ES 0x40
> +#define SR_TS 0x20
> +#define SR_RS 0x10
> +#define SR_TCS 0x08
> +#define SR_TBS 0x04
> +#define SR_DOS 0x02
> +#define SR_RBS 0x01
> +
> +/* ECC register */
> +#define ECC_SEG 0x1F
> +#define ECC_DIR 0x20
> +#define ECC_BIT 0x00
> +#define ECC_FORM 0x40
> +#define ECC_STUFF 0x80
> +#define ECC_MASK 0xc0
> +
> +/* 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);
> +
> +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;
> +
> +	/* For synchronize need_clear_alc/need_clear_ecc in worker & interrupt
> +	 * callback.
> +	 */
> +	spinlock_t lock;
> +	bool need_clear_alc;
> +	bool need_clear_ecc;
> +
> +	struct work_struct handle_clear_reg_work;
> +	struct work_struct handle_clear_overrun_work;
> +
> +	struct usb_device *dev;
> +	struct usb_interface *intf;
> +
> +	struct urb *int_urb;
> +	u8 int_read_buffer[F81604_INT_SIZE];
> +
> +	struct urb *read_urb[F81604_MAX_RX_URBS];
> +	u8 bulk_read_buffer[F81604_MAX_RX_URBS][F81604_BULK_SIZE];
> +
> +	struct urb *write_urb;
> +	u8 bulk_write_buffer[F81604_DATA_SIZE];
> +
> +	u8 ocr;
> +	u8 cdr;
> +};
> +
> +static int f81604_set_register(struct usb_device *dev, u16 reg, u8 data)
> +{
> +	size_t count = F81604_USB_MAX_RETRY;
> +	int status;
> +
> +	while (count--) {
> +		status = usb_control_msg_send(dev, 0, F81604_SET_GET_REGISTER,
> +					      USB_TYPE_VENDOR | USB_DIR_OUT, 0,
> +					      reg, &data, sizeof(u8),
> +					      F81604_USB_TIMEOUT, GFP_KERNEL);
> +		if (!status)
> +			break;
> +	}
> +
> +	if (status) {
> +		dev_err(&dev->dev, "%s: reg: %x data: %x failed: %d\n",
> +			__func__, reg, data, status);
> +	}
The { and } aren't needed as inside if is only one line.

> +
> +	return status;
> +}
> +
> +static int f81604_get_register(struct usb_device *dev, u16 reg, u8 *data)
> +{
> +	size_t count = F81604_USB_MAX_RETRY;
> +	int status;
> +
> +	while (count--) {
> +		status = usb_control_msg_recv(dev, 0, F81604_SET_GET_REGISTER,
> +					      USB_TYPE_VENDOR | USB_DIR_IN, 0,
> +					      reg, data, sizeof(u8),
> +					      F81604_USB_TIMEOUT, GFP_KERNEL);
> +		if (!status)
> +			break;
> +	}
> +
> +	if (status < 0) {
> +		dev_err(&dev->dev, "%s: reg: %x failed: %d\n", __func__, reg,
> +			status);
> +	}
the same, and also if (status) is more preferable I think, and You also used it
previously.

> +
> +	return status;
> +}
> +
> +static int f81604_set_sja1000_register(struct usb_device *dev, u8 port,
> +				       u16 reg, u8 data)
> +{
> +	int real_reg;
> +
> +	real_reg = reg + F81604_PORT_OFFSET * port + F81604_PORT_OFFSET;
> +	return f81604_set_register(dev, real_reg, data);
> +}
> +
> +static int f81604_get_sja1000_register(struct usb_device *dev, u8 port,
> +				       u16 reg, u8 *data)
> +{
> +	int real_reg;
> +
> +	real_reg = reg + F81604_PORT_OFFSET * port + F81604_PORT_OFFSET;
> +	return f81604_get_register(dev, real_reg, data);
> +}
> +
> +static int f81604_set_reset_mode(struct net_device *netdev)
> +{
> +	struct f81604_port_priv *priv = netdev_priv(netdev);
> +	int status, i;
> +	u8 tmp;
> +
> +	/* disable interrupts */
> +	status = f81604_set_sja1000_register(priv->dev, netdev->dev_id,
> +					     SJA1000_IER, IRQ_OFF);
> +	if (status)
> +		return status;
> +
> +	for (i = 0; i < 100; i++) {
Why 100? Maybe define to name it somehow

> +		status = f81604_get_sja1000_register(priv->dev, netdev->dev_id,
> +						     SJA1000_MOD, &tmp);
> +		if (status)
> +			return status;
> +
> +		/* check reset bit */
> +		if (tmp & MOD_RM) {
> +			priv->can.state = CAN_STATE_STOPPED;
> +			return 0;
> +		}
> +
> +		/* reset chip */
> +		status = f81604_set_sja1000_register(priv->dev, netdev->dev_id,
> +						     SJA1000_MOD, MOD_RM);
> +		if (status)
> +			return status;
> +	}
> +
> +	netdev_err(netdev, "setting SJA1000 into reset mode failed!\n");
> +	return -EINVAL;
> +}
> +
> +static int f81604_set_normal_mode(struct net_device *netdev)
> +{
> +	struct f81604_port_priv *priv = netdev_priv(netdev);
> +	int status, i;
> +	u8 mod_reg_val = 0x00;
RCT, mod_reg should be one line above

> +	u8 ier = 0;
> +	u8 tmp;
> +
> +	for (i = 0; i < 100; i++) {
> +		status = f81604_get_sja1000_register(priv->dev, netdev->dev_id,
> +						     SJA1000_MOD, &tmp);
> +		if (status)
> +			return status;
> +
> +		/* check reset bit */
> +		if ((tmp & MOD_RM) == 0) {
> +			priv->can.state = CAN_STATE_ERROR_ACTIVE;
> +			/* enable interrupts, RI handled by bulk-in */
> +			if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
> +				ier = IRQ_ALL & ~IRQ_RI;
> +			else
> +				ier = IRQ_ALL & ~(IRQ_RI | IRQ_BEI);
> +
> +			status = f81604_set_sja1000_register(priv->dev,
> +							     netdev->dev_id,
> +							     SJA1000_IER,
> +							     ier);
> +
> +			return status;
> +		}
> +
> +		/* set chip to normal mode */
> +		if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
> +			mod_reg_val |= MOD_LOM;
> +		if (priv->can.ctrlmode & CAN_CTRLMODE_PRESUME_ACK)
> +			mod_reg_val |= MOD_STM;
> +
> +		status = f81604_set_sja1000_register(priv->dev, netdev->dev_id,
> +						     SJA1000_MOD, mod_reg_val);
> +		if (status)
> +			return status;
> +	}
> +
> +	netdev_err(netdev, "setting SJA1000 into normal mode failed!\n");
> +	return -EINVAL;
> +}
> +
> +static int f81604_chipset_init(struct net_device *netdev)
> +{
> +	struct f81604_port_priv *priv = netdev_priv(netdev);
> +	int status;
> +	int i;
> +
> +	/* set clock divider and output control register */
> +	status = f81604_set_sja1000_register(priv->dev, netdev->dev_id,
> +					     SJA1000_CDR,
> +					     priv->cdr | CDR_PELICAN);
> +	if (status)
> +		return status;
> +
> +	/* set acceptance filter (accept all) */
> +	for (i = 0; i < 4; ++i) {
4 is a number of filters?

> +		status = f81604_set_sja1000_register(priv->dev, netdev->dev_id,
> +						     SJA1000_ACCC0 + i, 0);
> +		if (status)
> +			return status;
> +	}
> +
> +	for (i = 0; i < 4; ++i) {
> +		status = f81604_set_sja1000_register(priv->dev, netdev->dev_id,
> +						     SJA1000_ACCM0 + i, 0xFF);
> +		if (status)
> +			return status;
> +	}
> +
> +	return f81604_set_sja1000_register(priv->dev, netdev->dev_id,
> +					   SJA1000_OCR,
> +					   priv->ocr | OCR_MODE_NORMAL);
> +}
> +
> +static void f81604_unregister_urbs(struct net_device *netdev)
> +{
> +	struct f81604_port_priv *priv = netdev_priv(netdev);
> +	int i;
> +
> +	usb_kill_urb(priv->write_urb);
> +
> +	for (i = 0; i < F81604_MAX_RX_URBS; ++i)
> +		usb_kill_urb(priv->read_urb[i]);
> +
> +	usb_kill_urb(priv->int_urb);
> +}
> +
> +static int f81604_register_urbs(struct net_device *netdev)
> +{
> +	struct f81604_port_priv *priv = netdev_priv(netdev);
> +	int status, i;
> +
> +	for (i = 0; i < F81604_MAX_RX_URBS; ++i) {
> +		status = usb_submit_urb(priv->read_urb[i], GFP_KERNEL);
> +		if (status) {
> +			netdev_warn(netdev, "%s: submit rx urb failed: %d\n",
> +				    __func__, status);
> +			return status;
Don't know usb subsytem, but shouldn't previously submitted urb be
killed?

> +		}
> +	}
> +
> +	status = usb_submit_urb(priv->int_urb, GFP_KERNEL);
> +	if (status) {
> +		netdev_warn(netdev, "%s: submit int urb failed: %d\n",
> +			    __func__, status);
> +		return status;
The same here

> +	}
> +
> +	return 0;
> +}
> +
> +static int f81604_start(struct net_device *netdev)
> +{
> +	struct f81604_port_priv *priv = netdev_priv(netdev);
> +	int status;
> +	u8 mode;
> +	u8 tmp;
> +
> +	f81604_unregister_urbs(netdev);
> +
> +	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;
> +
> +	status = f81604_set_sja1000_register(priv->dev, netdev->dev_id, 0x80,
> +					     mode);
> +	if (status)
> +		return status;
> +
> +	/* set reset mode */
> +	status = f81604_set_reset_mode(netdev);
> +	if (status)
> +		return status;
> +
> +	status = f81604_chipset_init(netdev);
> +	if (status)
> +		return status;
> +
> +	/* Clear error counters and error code capture */
> +	status = f81604_set_sja1000_register(priv->dev, netdev->dev_id,
> +					     SJA1000_TXERR, 0);
> +	if (status)
> +		return status;
> +
> +	status = f81604_set_sja1000_register(priv->dev, netdev->dev_id,
> +					     SJA1000_RXERR, 0);
> +	if (status)
> +		return status;
> +
> +	/* Read clear for ECC/ALC/IR register */
> +	status = f81604_get_sja1000_register(priv->dev, netdev->dev_id,
> +					     SJA1000_ECC, &tmp);
> +	if (status)
> +		return status;
> +
> +	status = f81604_get_sja1000_register(priv->dev, netdev->dev_id,
> +					     SJA1000_ALC, &tmp);
> +	if (status)
> +		return status;
> +
> +	status = f81604_get_sja1000_register(priv->dev, netdev->dev_id,
> +					     SJA1000_IR, &tmp);
> +	if (status)
> +		return status;
> +
> +	status = f81604_register_urbs(netdev);
> +	if (status)
> +		return status;
> +
> +	return f81604_set_normal_mode(netdev);
> +}
> +
> +static int f81604_set_bittiming(struct net_device *dev)
> +{
> +	struct f81604_port_priv *priv = netdev_priv(dev);
> +	struct can_bittiming *bt;
> +	int status = 0;
> +	u8 btr0, btr1;
> +
> +	bt = &priv->can.bittiming;
> +	btr0 = ((bt->brp - 1) & 0x3f) | (((bt->sjw - 1) & 0x3) << 6);
> +	btr1 = ((bt->prop_seg + bt->phase_seg1 - 1) & 0xf) |
> +	       (((bt->phase_seg2 - 1) & 0x7) << 4);
> +
> +	if (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
> +		btr1 |= 0x80;
> +
> +	netdev_info(dev, "BTR0=0x%02x BTR1=0x%02x\n", btr0, btr1);
> +
> +	status = f81604_set_sja1000_register(priv->dev, dev->dev_id,
> +					     SJA1000_BTR0, btr0);
> +	if (status) {
> +		netdev_warn(dev, "%s: Set BTR0 failed: %d\n", __func__,
> +			    status);
> +		return status;
> +	}
> +
> +	status = f81604_set_sja1000_register(priv->dev, dev->dev_id,
> +					     SJA1000_BTR1, btr1);
> +	if (status) {
> +		netdev_warn(dev, "%s: Set BTR1 failed: %d\n", __func__,
> +			    status);
> +		return status;
> +	}
> +
> +	return 0;
> +}
> +
> +static int f81604_set_mode(struct net_device *netdev, enum can_mode mode)
> +{
> +	int err;
> +
> +	switch (mode) {
> +	case CAN_MODE_START:
> +		err = f81604_start(netdev);
> +		if (!err && netif_queue_stopped(netdev))
> +			netif_wake_queue(netdev);
> +		break;
> +
> +	default:
> +		err = -EOPNOTSUPP;
> +	}
> +
> +	return err;
> +}
> +
> +static void f81604_process_rx_packet(struct urb *urb)
> +{
> +	struct net_device_stats *stats;
> +	struct net_device *netdev;
> +	struct can_frame *cf;
> +	struct sk_buff *skb;
> +	u8 *data;
> +	u8 *ptr;
> +	int i;
> +	int count;
RCT

> +
> +	netdev = urb->context;
> +	stats = &netdev->stats;
> +	data = urb->transfer_buffer;
netdev and data can be set in declaration

> +
> +	if (urb->actual_length % 14) {
> +		netdev_warn(netdev, "actual_length %% 14 != 0 (%d)\n",
> +			    urb->actual_length);
> +	} else if (!urb->actual_length) {
> +		netdev_warn(netdev, "actual_length = 0 (%d)\n",
> +			    urb->actual_length);
> +	}
if ()

else ()

{} aren't needed here

> +
> +	count = urb->actual_length / F81604_DATA_SIZE;
> +
> +	for (i = 0; i < count; ++i) {
> +		ptr = &data[i * F81604_DATA_SIZE];
> +
> +		if (ptr[F81604_CMD_OFFSET] != F81604_CMD_DATA)
> +			continue;
> +
> +		skb = alloc_can_skb(netdev, &cf);
> +		if (!skb) {
> +			netdev_warn(netdev, "%s: not enough memory", __func__);
> +			continue;
> +		}
> +
> +		cf->can_dlc = can_cc_dlc2len(ptr[F81604_DLC_OFFSET] & 0xF);
> +
> +		if (ptr[F81604_DLC_OFFSET] & F81604_EFF_BIT) {
> +			cf->can_id = (ptr[F81604_ID1_OFFSET] << 21) |
> +				     (ptr[F81604_ID2_OFFSET] << 13) |
> +				     (ptr[F81604_ID3_OFFSET] << 5) |
> +				     (ptr[F81604_ID4_OFFSET] >> 3);
> +			cf->can_id |= CAN_EFF_FLAG;
> +		} else {
> +			cf->can_id = (ptr[F81604_ID1_OFFSET] << 3) |
> +				     (ptr[F81604_ID2_OFFSET] >> 5);
> +		}
> +
> +		if (ptr[F81604_DLC_OFFSET] & F81604_RTR_BIT) {
> +			cf->can_id |= CAN_RTR_FLAG;
> +		} else if (ptr[F81604_DLC_OFFSET] & F81604_EFF_BIT) {
> +			memcpy(cf->data, &ptr[F81604_EFF_DATA_OFFSET],
> +			       cf->can_dlc);
> +		} else {
> +			memcpy(cf->data, &ptr[F81604_SFF_DATA_OFFSET],
> +			       cf->can_dlc);
> +		}
> +
> +		stats->rx_packets++;
> +		stats->rx_bytes += cf->can_dlc;
> +		netif_rx(skb);
> +	}
> +}
> +
> +static void f81604_read_bulk_callback(struct urb *urb)
> +{
> +	struct net_device *netdev;
> +	int status;
> +	u8 *data;
> +
> +	netdev = urb->context;
> +	data = urb->transfer_buffer;
netdev and data can be set in declaration

> +
> +	if (!netif_device_present(netdev))
> +		return;
> +
> +	switch (urb->status) {
> +	case 0: /* success */
> +		break;
> +
> +	case -ENOENT:
> +	case -EPIPE:
> +	case -EPROTO:
> +	case -ESHUTDOWN:
> +		netdev_info(netdev, "%s: URB aborted (%d)\n", __func__,
> +			    urb->status);
> +		return;
> +
> +	default:
> +		netdev_info(netdev, "%s: URB aborted (%d)\n", __func__,
> +			    urb->status);
> +		goto resubmit_urb;
> +	}
> +
> +	switch (data[F81604_CMD_OFFSET]) {
> +	case F81604_CMD_DATA:
> +		f81604_process_rx_packet(urb);
> +		break;
> +	default:
> +		netdev_err(netdev, "unknown header: %x, len: %d\n",
> +			   data[F81604_CMD_OFFSET], urb->actual_length);
> +		break;
> +	}
> +
> +resubmit_urb:
> +	status = usb_submit_urb(urb, GFP_ATOMIC);
> +	if (status == -ENODEV) {
> +		netif_device_detach(netdev);
> +	} else if (status) {
> +		netdev_err(netdev, "failed resubmitting read bulk urb: %d\n",
> +			   status);
> +	}
> +}
> +
> +static void f81604_write_bulk_callback(struct urb *urb)
> +{
> +	struct f81604_port_priv *priv;
> +	struct net_device *netdev;
> +	int r;
> +
> +	netdev = urb->context;
> +	priv = netdev_priv(netdev);
Can be set in declaration

> +
> +	if (!netif_device_present(netdev))
> +		return;
> +
> +	switch (urb->status) {
> +	case 0: /* success */
> +		break;
> +
> +	case -ENOENT:
> +	case -EPIPE:
> +	case -EPROTO:
> +	case -ESHUTDOWN:
> +	default:
> +		netdev_info(netdev, "Tx URB error (%d)\n", urb->status);
> +		return;
> +	}
if (urb->status) {
	...
}

> +
> +	r = can_get_echo_skb(netdev, 0, NULL);
> +	if (r)
> +		netdev_warn(netdev, "can_get_echo_skb() failed: %d\n", r);
> +}
> +
> +static void f81604_handle_clear_overrun_work(struct work_struct *work)
> +{
> +	struct f81604_port_priv *priv;
> +	struct net_device *netdev;
> +
> +	priv = container_of(work, struct f81604_port_priv,
> +			    handle_clear_overrun_work);
> +	netdev = priv->netdev;
> +
> +	f81604_set_sja1000_register(priv->dev, netdev->dev_id, SJA1000_CMR,
> +				    CMD_CDO);
> +}
> +
> +static void f81604_handle_clear_reg_work(struct work_struct *work)
> +{
> +	struct f81604_port_priv *priv;
> +	struct net_device *netdev;
> +	bool clear_ecc, clear_alc;
> +	unsigned long flags;
> +	u8 tmp;
> +
> +	priv = container_of(work, struct f81604_port_priv,
> +			    handle_clear_reg_work);
> +	netdev = priv->netdev;
> +
> +	spin_lock_irqsave(&priv->lock, flags);
> +	clear_alc = priv->need_clear_alc;
> +	clear_ecc = priv->need_clear_ecc;
> +	priv->need_clear_alc = false;
> +	priv->need_clear_ecc = false;
> +	spin_unlock_irqrestore(&priv->lock, flags);
> +
> +	if (clear_alc) {
> +		f81604_get_sja1000_register(priv->dev, netdev->dev_id,
> +					    SJA1000_ALC, &tmp);
> +	}
> +
> +	if (clear_ecc) {
> +		f81604_get_sja1000_register(priv->dev, netdev->dev_id,
> +					    SJA1000_ECC, &tmp);
> +	}
> +}
> +
> +static void f81604_read_int_callback(struct urb *urb)
> +{
> +	struct net_device_stats *stats;
> +	struct f81604_port_priv *priv;
> +	struct net_device *netdev;
> +	struct can_frame *cf;
> +	struct sk_buff *skb;
> +	enum can_state can_state;
> +	enum can_state rx_state, tx_state;
> +	u8 *data;
> +	u8 sr, isrc, alc, ecc;
> +	u8 rxerr, txerr;
> +	unsigned long flags;
> +	int status;
RCT

> +
> +	netdev = urb->context;
> +	priv = netdev_priv(netdev);
> +	stats = &netdev->stats;
> +	can_state = priv->can.state;
> +	data = urb->transfer_buffer;
> +
> +	if (!netif_device_present(netdev))
> +		return;
> +
> +	switch (urb->status) {
> +	case 0: /* success */
> +		break;
> +
> +	case -ENOENT:
> +	case -EPIPE:
> +	case -EPROTO:
> +	case -ESHUTDOWN:
> +		netdev_info(netdev, "%s: Int URB aborted (%d)\n", __func__,
> +			    urb->status);
> +		return;
> +
> +	default:
> +		netdev_info(netdev, "%s: Int URB aborted (%d)\n", __func__,
> +			    urb->status);
> +		goto resubmit_urb;
> +	}
> +
> +	/* Int EP Read data format: SR/IR/IER/ALC/ECC/EWLR/RXERR/TXERR/VAL
> +	 * Note: ALC/ECC will not auto clear by here, must to read clear by
> +	 * read register (via handle_clear_reg_work).
> +	 */
> +	sr = data[0];
> +	isrc = data[1];
> +	alc = data[3];
> +	ecc = data[4];
> +	rxerr = data[6];
> +	txerr = data[7];
> +
> +	/* handle can bus errors */
> +	if (isrc & (IRQ_DOI | IRQ_EI | IRQ_BEI | IRQ_EPI | IRQ_ALI)) {
> +		skb = alloc_can_err_skb(netdev, &cf);
> +		if (!skb) {
> +			netdev_warn(netdev,
> +				    "no memory to alloc_can_err_skb\n");
> +			goto resubmit_urb;
> +		}
> +
> +		cf->data[6] = txerr;
> +		cf->data[7] = rxerr;
> +
> +		if (isrc & IRQ_DOI) {
> +			/* data overrun interrupt */
> +			netdev_dbg(netdev, "data overrun interrupt\n");
> +			cf->can_id |= CAN_ERR_CRTL;
> +			cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
> +			stats->rx_over_errors++;
> +			stats->rx_errors++;
> +
> +			schedule_work(&priv->handle_clear_overrun_work);
> +		}
> +
> +		if (isrc & IRQ_EI) {
> +			/* error warning interrupt */
> +			netdev_dbg(netdev, "error warning interrupt\n");
> +
> +			if (sr & SR_BS)
> +				can_state = CAN_STATE_BUS_OFF;
> +			else if (sr & SR_ES)
> +				can_state = CAN_STATE_ERROR_WARNING;
> +			else
> +				can_state = CAN_STATE_ERROR_ACTIVE;
> +		}
> +
> +		if (isrc & IRQ_BEI) {
> +			/* bus error interrupt */
> +			netdev_dbg(netdev, "bus error interrupt\n");
> +
> +			priv->can.can_stats.bus_error++;
> +			stats->rx_errors++;
> +
> +			cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
> +
> +			/* set error type */
> +			switch (ecc & ECC_MASK) {
> +			case ECC_BIT:
> +				cf->data[2] |= CAN_ERR_PROT_BIT;
> +				break;
> +			case ECC_FORM:
> +				cf->data[2] |= CAN_ERR_PROT_FORM;
> +				break;
> +			case ECC_STUFF:
> +				cf->data[2] |= CAN_ERR_PROT_STUFF;
> +				break;
> +			default:
> +				break;
> +			}
> +
> +			/* set error location */
> +			cf->data[3] = ecc & ECC_SEG;
> +
> +			/* Error occurred during transmission? */
> +			if ((ecc & ECC_DIR) == 0)
> +				cf->data[2] |= CAN_ERR_PROT_TX;
> +
> +			spin_lock_irqsave(&priv->lock, flags);
> +			priv->need_clear_ecc = true;
> +			spin_unlock_irqrestore(&priv->lock, flags);
> +
> +			schedule_work(&priv->handle_clear_reg_work);
> +		}
> +
> +		if (isrc & 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: %x\n",
> +				   can_state);
> +		}
> +
> +		if (isrc & IRQ_ALI) {
> +			/* arbitration lost interrupt */
> +			netdev_dbg(netdev, "arbitration lost interrupt\n");
> +
> +			priv->can.can_stats.arbitration_lost++;
> +			stats->tx_errors++;
> +			cf->can_id |= CAN_ERR_LOSTARB;
> +			cf->data[0] = alc & 0x1f;
> +
> +			spin_lock_irqsave(&priv->lock, flags);
> +			priv->need_clear_alc = true;
> +			spin_unlock_irqrestore(&priv->lock, flags);
> +
> +			schedule_work(&priv->handle_clear_reg_work);
> +		}
> +
> +		if (can_state != priv->can.state) {
> +			tx_state = txerr >= rxerr ? can_state : 0;
> +			rx_state = txerr <= rxerr ? can_state : 0;
> +
> +			can_change_state(netdev, cf, tx_state, rx_state);
> +
> +			if (can_state == CAN_STATE_BUS_OFF)
> +				can_bus_off(netdev);
> +		}
> +
> +		stats->rx_packets++;
> +		stats->rx_bytes += cf->can_dlc;
> +		netif_rx(skb);
> +	}
> +
> +	/* handle TX */
> +	if ((isrc & IRQ_TI) && can_state != CAN_STATE_BUS_OFF) {
> +		/* transmission buffer released */
> +		if (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT &&
> +		    !(sr & 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);
> +	}
> +
> +resubmit_urb:
> +	status = usb_submit_urb(urb, GFP_ATOMIC);
> +	if (status) {
> +		netdev_err(netdev,
> +			   "%s: failed resubmitting int bulk urb: %d\n",
> +			   __func__, status);
> +
> +		if (status == -ENODEV)
> +			netif_device_detach(netdev);
> +	}
> +}
> +
> +static netdev_tx_t f81604_start_xmit(struct sk_buff *skb,
> +				     struct net_device *netdev)
> +{
> +	struct net_device_stats *stats;
> +	struct f81604_port_priv *priv;
> +	struct can_frame *cf;
> +	int status;
> +	u8 *ptr;
> +	u32 id;
> +
> +	priv = netdev_priv(netdev);
> +	cf = (struct can_frame *)skb->data;
> +	stats = &netdev->stats;
> +
> +	if (can_dropped_invalid_skb(netdev, skb))
> +		return NETDEV_TX_OK;
> +
> +	netif_stop_queue(netdev);
> +
> +	ptr = priv->bulk_write_buffer;
> +	memset(ptr, 0, F81604_DATA_SIZE);
> +
> +	ptr[0] = F81604_CMD_DATA;
> +	ptr[1] = min_t(u8, cf->can_dlc & 0xf, 8);
> +
> +	if (cf->can_id & CAN_EFF_FLAG) {
> +		id = (cf->can_id & CAN_ERR_MASK) << 3;
> +		ptr[1] |= F81604_EFF_BIT;
> +		ptr[2] = (id >> 24) & 0xff;
> +		ptr[3] = (id >> 16) & 0xff;
> +		ptr[4] = (id >> 8) & 0xff;
> +		ptr[5] = (id >> 0) & 0xff;
> +		memcpy(&ptr[6], cf->data, ptr[1]);
> +	} else {
> +		id = (cf->can_id & CAN_ERR_MASK) << 5;
> +		ptr[2] = (id >> 8) & 0xff;
> +		ptr[3] = (id >> 0) & 0xff;
> +		memcpy(&ptr[4], cf->data, ptr[1]);
> +	}
> +
> +	if (cf->can_id & CAN_RTR_FLAG)
> +		ptr[1] |= F81604_RTR_BIT;
> +
> +	can_put_echo_skb(skb, netdev, 0, 0);
> +
> +	status = usb_submit_urb(priv->write_urb, GFP_ATOMIC);
> +	if (status) {
> +		netdev_err(netdev, "%s: failed resubmitting tx bulk urb: %d\n",
> +			   __func__, status);
> +
> +		can_free_echo_skb(netdev, 0, NULL);
> +		stats->tx_dropped++;
> +
> +		if (status == -ENODEV)
> +			netif_device_detach(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);
> +	int status;
> +	u8 txerr;
> +	u8 rxerr;
> +
> +	status = f81604_get_sja1000_register(priv->dev, netdev->dev_id,
> +					     SJA1000_TXERR, &txerr);
> +	if (status)
> +		return status;
> +
> +	status = f81604_get_sja1000_register(priv->dev, netdev->dev_id,
> +					     SJA1000_RXERR, &rxerr);
> +	if (status)
> +		return status;
> +
> +	bec->txerr = txerr;
> +	bec->rxerr = rxerr;
> +
> +	return 0;
> +}
> +
> +static void f81604_remove_urbs(struct net_device *netdev)
> +{
> +	struct f81604_port_priv *priv = netdev_priv(netdev);
> +	int i;
> +
> +	for (i = 0; i < F81604_MAX_RX_URBS; ++i)
> +		usb_free_urb(priv->read_urb[i]);
> +
> +	usb_free_urb(priv->write_urb);
> +	usb_free_urb(priv->int_urb);
> +}
> +
> +static int f81604_prepare_urbs(struct net_device *netdev)
> +{
> +	static u8 bulk_in_addr[F81604_MAX_DEV] = { 0x82, 0x84 };
> +	static u8 bulk_out_addr[F81604_MAX_DEV] = { 0x01, 0x03 };
> +	static u8 int_in_addr[F81604_MAX_DEV] = { 0x81, 0x83 };
> +	struct f81604_port_priv *priv;
> +	int id;
> +	int i;
> +
> +	priv = netdev_priv(netdev);
> +	id = netdev->dev_id;
> +
> +	/* initialize to NULL for error recovery */
> +	for (i = 0; i < F81604_MAX_RX_URBS; ++i)
> +		priv->read_urb[i] = NULL;
> +
> +	priv->write_urb = NULL;
> +	priv->int_urb = NULL;
> +
> +	for (i = 0; i < F81604_MAX_RX_URBS; ++i) {
> +		priv->read_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
> +		if (!priv->read_urb[i])
> +			goto error;
> +
> +		usb_fill_bulk_urb(priv->read_urb[i], priv->dev,
> +				  usb_rcvbulkpipe(priv->dev, bulk_in_addr[id]),
> +				  priv->bulk_read_buffer[i], F81604_BULK_SIZE,
> +				  f81604_read_bulk_callback, netdev);
> +	}
> +
> +	priv->write_urb = usb_alloc_urb(0, GFP_KERNEL);
> +	if (!priv->write_urb)
> +		goto error;
> +
> +	usb_fill_bulk_urb(priv->write_urb, priv->dev,
> +			  usb_sndbulkpipe(priv->dev, bulk_out_addr[id]),
> +			  priv->bulk_write_buffer, F81604_DATA_SIZE,
> +			  f81604_write_bulk_callback, netdev);
> +
> +	priv->int_urb = usb_alloc_urb(0, GFP_KERNEL);
> +	if (!priv->int_urb)
> +		goto error;
> +
> +	usb_fill_int_urb(priv->int_urb, priv->dev,
> +			 usb_rcvintpipe(priv->dev, int_in_addr[id]),
> +			 priv->int_read_buffer, F81604_INT_SIZE,
> +			 f81604_read_int_callback, netdev, 1);
> +
> +	return 0;
> +
> +error:
> +	f81604_remove_urbs(netdev);
> +	return -ENOMEM;
> +}
> +
> +/* Open USB device */
> +static int f81604_open(struct net_device *netdev)
> +{
> +	int err;
> +
> +	err = f81604_prepare_urbs(netdev);
> +	if (err)
> +		return err;
> +
> +	err = open_candev(netdev);
> +	if (err)
> +		goto remove_urbs;
> +
> +	err = f81604_start(netdev);
> +	if (err)
> +		goto start_failed;
> +
> +	netif_start_queue(netdev);
> +	return 0;
> +
> +start_failed:
> +	if (err == -ENODEV)
> +		netif_device_detach(netdev);
> +
> +	close_candev(netdev);
> +
> +remove_urbs:
> +	f81604_remove_urbs(netdev);
> +
> +	return err;
> +}
> +
> +/* Close USB device */
> +static int f81604_close(struct net_device *netdev)
> +{
> +	struct f81604_port_priv *priv = netdev_priv(netdev);
> +
> +	f81604_set_reset_mode(netdev);
> +
> +	netif_stop_queue(netdev);
> +	cancel_work_sync(&priv->handle_clear_overrun_work);
> +	cancel_work_sync(&priv->handle_clear_reg_work);
> +	close_candev(netdev);
> +
> +	f81604_unregister_urbs(netdev);
> +	f81604_remove_urbs(netdev);
> +
> +	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 = "f81604",
> +	.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 < F81604_MAX_DEV; ++i) {
> +		if (!priv->netdev[i])
> +			continue;
> +
> +		unregister_netdev(priv->netdev[i]);
> +		free_candev(priv->netdev[i]);
> +	}
What about closing USB device? It is called brefore disconnect or it
should be done here?

> +}
> +
> +static int f81604_probe(struct usb_interface *intf,
> +			const struct usb_device_id *id)
> +{
> +	struct f81604_port_priv *port_priv;
> +	struct net_device *netdev;
> +	struct f81604_priv *priv;
> +	struct usb_device *dev;
> +	int i, err;
> +
> +	dev_info(&intf->dev, "Detected Fintek F81604 device.\n");
> +	dev_info(&intf->dev,
> +		 "Please download newest driver from Fintek website\n");
> +	dev_info(&intf->dev, "if you want to use customized functions.\n");
> +
> +	dev = interface_to_usbdev(intf);
> +
> +	priv = devm_kzalloc(&intf->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	usb_set_intfdata(intf, priv);
> +
> +	for (i = 0; i < F81604_MAX_DEV; ++i) {
> +		netdev = alloc_candev(sizeof(*port_priv), 1);
> +		if (!netdev) {
> +			dev_err(&intf->dev, "Couldn't alloc candev: %d\n", i);
> +			err = -ENOMEM;
> +
> +			goto failure_cleanup;
> +		}
> +
> +		port_priv = netdev_priv(netdev);
> +		netdev->dev_id = i;
> +
> +		spin_lock_init(&port_priv->lock);
> +		INIT_WORK(&port_priv->handle_clear_overrun_work,
> +			  f81604_handle_clear_overrun_work);
> +		INIT_WORK(&port_priv->handle_clear_reg_work,
> +			  f81604_handle_clear_reg_work);
> +
> +		port_priv->intf = intf;
> +		port_priv->dev = dev;
> +		port_priv->ocr = OCR_TX0_PUSHPULL | OCR_TX1_PUSHPULL;
> +		port_priv->cdr = CDR_CBP;
> +		port_priv->can.state = CAN_STATE_STOPPED;
> +		port_priv->can.clock.freq = 24000000 / 2;
> +
> +		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_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;
> +
> +		port_priv->can.ctrlmode_supported |= CAN_CTRLMODE_PRESUME_ACK;
> +		netdev->netdev_ops = &f81604_netdev_ops;
> +		netdev->flags |= IFF_ECHO;
> +
> +		SET_NETDEV_DEV(netdev, &intf->dev);
> +
> +		err = register_candev(netdev);
> +		if (err) {
> +			netdev_err(netdev,
> +				   "couldn't register CAN device: %d\n", err);
> +			free_candev(netdev);
> +
> +			goto failure_cleanup;
> +		}
> +
> +		port_priv->netdev = netdev;
> +		priv->netdev[i] = netdev;
> +
> +		dev_info(&intf->dev, "Channel #%d registered as %s\n", i,
> +			 netdev->name);
> +	}
> +
> +	return 0;
> +
> +failure_cleanup:
> +	f81604_disconnect(intf);
> +	return err;
> +}
> +
> +static struct usb_driver f81604_driver = {
> +	.name = "f81604",
> +	.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");
> -- 
> 2.17.1
>