drivers/net/can/usb/peak_usb/pcan_usb.c - arm/linux - Git at Google

 /*
  * CAN driver for PEAK System PCAN-USB adapter
  * Derived from the PCAN project file driver/src/pcan_usb.c
  *
  * Copyright (C) 2003-2010 PEAK System-Technik GmbH
  * Copyright (C) 2011-2012 Stephane Grosjean <s.grosjean@peak-system.com>
  *
  * Many thanks to Klaus Hitschler <klaus.hitschler@gmx.de>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published
  * by the Free Software Foundation; version 2 of the License.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * General Public License for more details.
  */
 #include <linux/netdevice.h>
 #include <linux/usb.h>
 #include <linux/module.h>

 #include <linux/can.h>
 #include <linux/can/dev.h>
 #include <linux/can/error.h>

 #include "pcan_usb_core.h"

 MODULE_SUPPORTED_DEVICE("PEAK-System PCAN-USB adapter");

 /* PCAN-USB Endpoints */
 #define PCAN_USB_EP_CMDOUT		1
 #define PCAN_USB_EP_CMDIN		(PCAN_USB_EP_CMDOUT | USB_DIR_IN)
 #define PCAN_USB_EP_MSGOUT		2
 #define PCAN_USB_EP_MSGIN		(PCAN_USB_EP_MSGOUT | USB_DIR_IN)

 /* PCAN-USB command struct */
 #define PCAN_USB_CMD_FUNC		0
 #define PCAN_USB_CMD_NUM		1
 #define PCAN_USB_CMD_ARGS		2
 #define PCAN_USB_CMD_ARGS_LEN		14
 #define PCAN_USB_CMD_LEN		(PCAN_USB_CMD_ARGS + \
 					 PCAN_USB_CMD_ARGS_LEN)

 /* PCAN-USB command timeout (ms.) */
 #define PCAN_USB_COMMAND_TIMEOUT	1000

 /* PCAN-USB startup timeout (ms.) */
 #define PCAN_USB_STARTUP_TIMEOUT	10

 /* PCAN-USB rx/tx buffers size */
 #define PCAN_USB_RX_BUFFER_SIZE		64
 #define PCAN_USB_TX_BUFFER_SIZE		64

 #define PCAN_USB_MSG_HEADER_LEN		2

 /* PCAN-USB adapter internal clock (MHz) */
 #define PCAN_USB_CRYSTAL_HZ		16000000

 /* PCAN-USB USB message record status/len field */
 #define PCAN_USB_STATUSLEN_TIMESTAMP	(1 << 7)
 #define PCAN_USB_STATUSLEN_INTERNAL	(1 << 6)
 #define PCAN_USB_STATUSLEN_EXT_ID	(1 << 5)
 #define PCAN_USB_STATUSLEN_RTR		(1 << 4)
 #define PCAN_USB_STATUSLEN_DLC		(0xf)

 /* PCAN-USB error flags */
 #define PCAN_USB_ERROR_TXFULL		0x01
 #define PCAN_USB_ERROR_RXQOVR		0x02
 #define PCAN_USB_ERROR_BUS_LIGHT	0x04
 #define PCAN_USB_ERROR_BUS_HEAVY	0x08
 #define PCAN_USB_ERROR_BUS_OFF		0x10
 #define PCAN_USB_ERROR_RXQEMPTY		0x20
 #define PCAN_USB_ERROR_QOVR		0x40
 #define PCAN_USB_ERROR_TXQFULL		0x80

 /* SJA1000 modes */
 #define SJA1000_MODE_NORMAL		0x00
 #define SJA1000_MODE_INIT		0x01

 /*
  * tick duration = 42.666 us =>
  * (tick_number * 44739243) >> 20 ~ (tick_number * 42666) / 1000
  * accuracy = 10^-7
  */
 #define PCAN_USB_TS_DIV_SHIFTER		20
 #define PCAN_USB_TS_US_PER_TICK		44739243

 /* PCAN-USB messages record types */
 #define PCAN_USB_REC_ERROR		1
 #define PCAN_USB_REC_ANALOG		2
 #define PCAN_USB_REC_BUSLOAD		3
 #define PCAN_USB_REC_TS			4
 #define PCAN_USB_REC_BUSEVT		5

 /* private to PCAN-USB adapter */
 struct pcan_usb {
 	struct peak_usb_device dev;
 	struct peak_time_ref time_ref;
 	struct timer_list restart_timer;
 };

 /* incoming message context for decoding */
 struct pcan_usb_msg_context {
 	u16 ts16;
 	u8 prev_ts8;
 	u8 *ptr;
 	u8 *end;
 	u8 rec_cnt;
 	u8 rec_idx;
 	u8 rec_data_idx;
 	struct net_device *netdev;
 	struct pcan_usb *pdev;
 };

 /*
  * send a command
  */
 static int pcan_usb_send_cmd(struct peak_usb_device *dev, u8 f, u8 n, u8 *p)
 {
 	int err;
 	int actual_length;

 	/* usb device unregistered? */
 	if (!(dev->state & PCAN_USB_STATE_CONNECTED))
 		return 0;

 	dev->cmd_buf[PCAN_USB_CMD_FUNC] = f;
 	dev->cmd_buf[PCAN_USB_CMD_NUM] = n;

 	if (p)
 		memcpy(dev->cmd_buf + PCAN_USB_CMD_ARGS,
 			p, PCAN_USB_CMD_ARGS_LEN);

 	err = usb_bulk_msg(dev->udev,
 			usb_sndbulkpipe(dev->udev, PCAN_USB_EP_CMDOUT),
 			dev->cmd_buf, PCAN_USB_CMD_LEN, &actual_length,
 			PCAN_USB_COMMAND_TIMEOUT);
 	if (err)
 		netdev_err(dev->netdev,
 			"sending cmd f=0x%x n=0x%x failure: %d\n",
 			f, n, err);
 	return err;
 }

 /*
  * send a command then wait for its response
  */
 static int pcan_usb_wait_rsp(struct peak_usb_device *dev, u8 f, u8 n, u8 *p)
 {
 	int err;
 	int actual_length;

 	/* usb device unregistered? */
 	if (!(dev->state & PCAN_USB_STATE_CONNECTED))
 		return 0;

 	/* first, send command */
 	err = pcan_usb_send_cmd(dev, f, n, NULL);
 	if (err)
 		return err;

 	err = usb_bulk_msg(dev->udev,
 		usb_rcvbulkpipe(dev->udev, PCAN_USB_EP_CMDIN),
 		dev->cmd_buf, PCAN_USB_CMD_LEN, &actual_length,
 		PCAN_USB_COMMAND_TIMEOUT);
 	if (err)
 		netdev_err(dev->netdev,
 			"waiting rsp f=0x%x n=0x%x failure: %d\n", f, n, err);
 	else if (p)
 		memcpy(p, dev->cmd_buf + PCAN_USB_CMD_ARGS,
 			PCAN_USB_CMD_ARGS_LEN);

 	return err;
 }

 static int pcan_usb_set_sja1000(struct peak_usb_device *dev, u8 mode)
 {
 	u8 args[PCAN_USB_CMD_ARGS_LEN] = {
 		[1] = mode,
 	};

 	return pcan_usb_send_cmd(dev, 9, 2, args);
 }

 static int pcan_usb_set_bus(struct peak_usb_device *dev, u8 onoff)
 {
 	u8 args[PCAN_USB_CMD_ARGS_LEN] = {
 		[0] = !!onoff,
 	};

 	return pcan_usb_send_cmd(dev, 3, 2, args);
 }

 static int pcan_usb_set_silent(struct peak_usb_device *dev, u8 onoff)
 {
 	u8 args[PCAN_USB_CMD_ARGS_LEN] = {
 		[0] = !!onoff,
 	};

 	return pcan_usb_send_cmd(dev, 3, 3, args);
 }

 static int pcan_usb_set_ext_vcc(struct peak_usb_device *dev, u8 onoff)
 {
 	u8 args[PCAN_USB_CMD_ARGS_LEN] = {
 		[0] = !!onoff,
 	};

 	return pcan_usb_send_cmd(dev, 10, 2, args);
 }

 /*
  * set bittiming value to can
  */
 static int pcan_usb_set_bittiming(struct peak_usb_device *dev,
 				  struct can_bittiming *bt)
 {
 	u8 args[PCAN_USB_CMD_ARGS_LEN];
 	u8 btr0, btr1;

 	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 (dev->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
 		btr1 |= 0x80;

 	netdev_info(dev->netdev, "setting BTR0=0x%02x BTR1=0x%02x\n",
 		btr0, btr1);

 	args[0] = btr1;
 	args[1] = btr0;

 	return pcan_usb_send_cmd(dev, 1, 2, args);
 }

 /*
  * init/reset can
  */
 static int pcan_usb_write_mode(struct peak_usb_device *dev, u8 onoff)
 {
 	int err;

 	err = pcan_usb_set_bus(dev, onoff);
 	if (err)
 		return err;

 	if (!onoff) {
 		err = pcan_usb_set_sja1000(dev, SJA1000_MODE_INIT);
 	} else {
 		/* the PCAN-USB needs time to init */
 		set_current_state(TASK_INTERRUPTIBLE);
 		schedule_timeout(msecs_to_jiffies(PCAN_USB_STARTUP_TIMEOUT));
 	}

 	return err;
 }

 /*
  * handle end of waiting for the device to reset
  */
 static void pcan_usb_restart(unsigned long arg)
 {
 	/* notify candev and netdev */
 	peak_usb_restart_complete((struct peak_usb_device *)arg);
 }

 /*
  * handle the submission of the restart urb
  */
 static void pcan_usb_restart_pending(struct urb *urb)
 {
 	struct pcan_usb *pdev = urb->context;

 	/* the PCAN-USB needs time to restart */
 	mod_timer(&pdev->restart_timer,
 			jiffies + msecs_to_jiffies(PCAN_USB_STARTUP_TIMEOUT));

 	/* can delete usb resources */
 	peak_usb_async_complete(urb);
 }

 /*
  * handle asynchronous restart
  */
 static int pcan_usb_restart_async(struct peak_usb_device *dev, struct urb *urb,
 				  u8 *buf)
 {
 	struct pcan_usb *pdev = container_of(dev, struct pcan_usb, dev);

 	if (timer_pending(&pdev->restart_timer))
 		return -EBUSY;

 	/* set bus on */
 	buf[PCAN_USB_CMD_FUNC] = 3;
 	buf[PCAN_USB_CMD_NUM] = 2;
 	buf[PCAN_USB_CMD_ARGS] = 1;

 	usb_fill_bulk_urb(urb, dev->udev,
 			usb_sndbulkpipe(dev->udev, PCAN_USB_EP_CMDOUT),
 			buf, PCAN_USB_CMD_LEN,
 			pcan_usb_restart_pending, pdev);

 	return usb_submit_urb(urb, GFP_ATOMIC);
 }

 /*
  * read serial number from device
  */
 static int pcan_usb_get_serial(struct peak_usb_device *dev, u32 *serial_number)
 {
 	u8 args[PCAN_USB_CMD_ARGS_LEN];
 	int err;

 	err = pcan_usb_wait_rsp(dev, 6, 1, args);
 	if (err) {
 		netdev_err(dev->netdev, "getting serial failure: %d\n", err);
 	} else if (serial_number) {
 		u32 tmp32;

 		memcpy(&tmp32, args, 4);
 		*serial_number = le32_to_cpu(tmp32);
 	}

 	return err;
 }

 /*
  * read device id from device
  */
 static int pcan_usb_get_device_id(struct peak_usb_device *dev, u32 *device_id)
 {
 	u8 args[PCAN_USB_CMD_ARGS_LEN];
 	int err;

 	err = pcan_usb_wait_rsp(dev, 4, 1, args);
 	if (err)
 		netdev_err(dev->netdev, "getting device id failure: %d\n", err);
 	else if (device_id)
 		*device_id = args[0];

 	return err;
 }

 /*
  * update current time ref with received timestamp
  */
 static int pcan_usb_update_ts(struct pcan_usb_msg_context *mc)
 {
 	u16 tmp16;

 	if ((mc->ptr+2) > mc->end)
 		return -EINVAL;

 	memcpy(&tmp16, mc->ptr, 2);

 	mc->ts16 = le16_to_cpu(tmp16);

 	if (mc->rec_idx > 0)
 		peak_usb_update_ts_now(&mc->pdev->time_ref, mc->ts16);
 	else
 		peak_usb_set_ts_now(&mc->pdev->time_ref, mc->ts16);

 	return 0;
 }

 /*
  * decode received timestamp
  */
 static int pcan_usb_decode_ts(struct pcan_usb_msg_context *mc, u8 first_packet)
 {
 	/* only 1st packet supplies a word timestamp */
 	if (first_packet) {
 		u16 tmp16;

 		if ((mc->ptr + 2) > mc->end)
 			return -EINVAL;

 		memcpy(&tmp16, mc->ptr, 2);
 		mc->ptr += 2;

 		mc->ts16 = le16_to_cpu(tmp16);
 		mc->prev_ts8 = mc->ts16 & 0x00ff;
 	} else {
 		u8 ts8;

 		if ((mc->ptr + 1) > mc->end)
 			return -EINVAL;

 		ts8 = *mc->ptr++;

 		if (ts8 < mc->prev_ts8)
 			mc->ts16 += 0x100;

 		mc->ts16 &= 0xff00;
 		mc->ts16 |= ts8;
 		mc->prev_ts8 = ts8;
 	}

 	return 0;
 }

 static int pcan_usb_decode_error(struct pcan_usb_msg_context *mc, u8 n,
 				 u8 status_len)
 {
 	struct sk_buff *skb;
 	struct can_frame *cf;
 	struct timeval tv;
 	enum can_state new_state;

 	/* ignore this error until 1st ts received */
 	if (n == PCAN_USB_ERROR_QOVR)
 		if (!mc->pdev->time_ref.tick_count)
 			return 0;

 	new_state = mc->pdev->dev.can.state;

 	switch (mc->pdev->dev.can.state) {
 	case CAN_STATE_ERROR_ACTIVE:
 		if (n & PCAN_USB_ERROR_BUS_LIGHT) {
 			new_state = CAN_STATE_ERROR_WARNING;
 			break;
 		}

 	case CAN_STATE_ERROR_WARNING:
 		if (n & PCAN_USB_ERROR_BUS_HEAVY) {
 			new_state = CAN_STATE_ERROR_PASSIVE;
 			break;
 		}
 		if (n & PCAN_USB_ERROR_BUS_OFF) {
 			new_state = CAN_STATE_BUS_OFF;
 			break;
 		}
 		if (n & (PCAN_USB_ERROR_RXQOVR | PCAN_USB_ERROR_QOVR)) {
 			/*
 			 * trick to bypass next comparison and process other
 			 * errors
 			 */
 			new_state = CAN_STATE_MAX;
 			break;
 		}
 		if ((n & PCAN_USB_ERROR_BUS_LIGHT) == 0) {
 			/* no error (back to active state) */
 			mc->pdev->dev.can.state = CAN_STATE_ERROR_ACTIVE;
 			return 0;
 		}
 		break;

 	case CAN_STATE_ERROR_PASSIVE:
 		if (n & PCAN_USB_ERROR_BUS_OFF) {
 			new_state = CAN_STATE_BUS_OFF;
 			break;
 		}
 		if (n & PCAN_USB_ERROR_BUS_LIGHT) {
 			new_state = CAN_STATE_ERROR_WARNING;
 			break;
 		}
 		if (n & (PCAN_USB_ERROR_RXQOVR | PCAN_USB_ERROR_QOVR)) {
 			/*
 			 * trick to bypass next comparison and process other
 			 * errors
 			 */
 			new_state = CAN_STATE_MAX;
 			break;
 		}

 		if ((n & PCAN_USB_ERROR_BUS_HEAVY) == 0) {
 			/* no error (back to active state) */
 			mc->pdev->dev.can.state = CAN_STATE_ERROR_ACTIVE;
 			return 0;
 		}
 		break;

 	default:
 		/* do nothing waiting for restart */
 		return 0;
 	}

 	/* donot post any error if current state didn't change */
 	if (mc->pdev->dev.can.state == new_state)
 		return 0;

 	/* allocate an skb to store the error frame */
 	skb = alloc_can_err_skb(mc->netdev, &cf);
 	if (!skb)
 		return -ENOMEM;

 	switch (new_state) {
 	case CAN_STATE_BUS_OFF:
 		cf->can_id |= CAN_ERR_BUSOFF;
 		can_bus_off(mc->netdev);
 		break;

 	case CAN_STATE_ERROR_PASSIVE:
 		cf->can_id |= CAN_ERR_CRTL;
 		cf->data[1] |= CAN_ERR_CRTL_TX_PASSIVE |
 			       CAN_ERR_CRTL_RX_PASSIVE;
 		mc->pdev->dev.can.can_stats.error_passive++;
 		break;

 	case CAN_STATE_ERROR_WARNING:
 		cf->can_id |= CAN_ERR_CRTL;
 		cf->data[1] |= CAN_ERR_CRTL_TX_WARNING |
 			       CAN_ERR_CRTL_RX_WARNING;
 		mc->pdev->dev.can.can_stats.error_warning++;
 		break;

 	default:
 		/* CAN_STATE_MAX (trick to handle other errors) */
 		cf->can_id |= CAN_ERR_CRTL;
 		cf->data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;
 		mc->netdev->stats.rx_over_errors++;
 		mc->netdev->stats.rx_errors++;

 		new_state = mc->pdev->dev.can.state;
 		break;
 	}

 	mc->pdev->dev.can.state = new_state;

 	if (status_len & PCAN_USB_STATUSLEN_TIMESTAMP) {
 		struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);

 		peak_usb_get_ts_tv(&mc->pdev->time_ref, mc->ts16, &tv);
 		hwts->hwtstamp = timeval_to_ktime(tv);
 	}

 	netif_rx(skb);
 	mc->netdev->stats.rx_packets++;
 	mc->netdev->stats.rx_bytes += cf->can_dlc;

 	return 0;
 }

 /*
  * decode non-data usb message
  */
 static int pcan_usb_decode_status(struct pcan_usb_msg_context *mc,
 				  u8 status_len)
 {
 	u8 rec_len = status_len & PCAN_USB_STATUSLEN_DLC;
 	u8 f, n;
 	int err;

 	/* check whether function and number can be read */
 	if ((mc->ptr + 2) > mc->end)
 		return -EINVAL;

 	f = mc->ptr[PCAN_USB_CMD_FUNC];
 	n = mc->ptr[PCAN_USB_CMD_NUM];
 	mc->ptr += PCAN_USB_CMD_ARGS;

 	if (status_len & PCAN_USB_STATUSLEN_TIMESTAMP) {
 		int err = pcan_usb_decode_ts(mc, !mc->rec_idx);

 		if (err)
 			return err;
 	}

 	switch (f) {
 	case PCAN_USB_REC_ERROR:
 		err = pcan_usb_decode_error(mc, n, status_len);
 		if (err)
 			return err;
 		break;

 	case PCAN_USB_REC_ANALOG:
 		/* analog values (ignored) */
 		rec_len = 2;
 		break;

 	case PCAN_USB_REC_BUSLOAD:
 		/* bus load (ignored) */
 		rec_len = 1;
 		break;

 	case PCAN_USB_REC_TS:
 		/* only timestamp */
 		if (pcan_usb_update_ts(mc))
 			return -EINVAL;
 		break;

 	case PCAN_USB_REC_BUSEVT:
 		/* error frame/bus event */
 		if (n & PCAN_USB_ERROR_TXQFULL)
 			netdev_dbg(mc->netdev, "device Tx queue full)\n");
 		break;
 	default:
 		netdev_err(mc->netdev, "unexpected function %u\n", f);
 		break;
 	}

 	if ((mc->ptr + rec_len) > mc->end)
 		return -EINVAL;

 	mc->ptr += rec_len;

 	return 0;
 }

 /*
  * decode data usb message
  */
 static int pcan_usb_decode_data(struct pcan_usb_msg_context *mc, u8 status_len)
 {
 	u8 rec_len = status_len & PCAN_USB_STATUSLEN_DLC;
 	struct sk_buff *skb;
 	struct can_frame *cf;
 	struct timeval tv;
 	struct skb_shared_hwtstamps *hwts;

 	skb = alloc_can_skb(mc->netdev, &cf);
 	if (!skb)
 		return -ENOMEM;

 	if (status_len & PCAN_USB_STATUSLEN_EXT_ID) {
 		u32 tmp32;

 		if ((mc->ptr + 4) > mc->end)
 			goto decode_failed;

 		memcpy(&tmp32, mc->ptr, 4);
 		mc->ptr += 4;

 		cf->can_id = le32_to_cpu(tmp32 >> 3) | CAN_EFF_FLAG;
 	} else {
 		u16 tmp16;

 		if ((mc->ptr + 2) > mc->end)
 			goto decode_failed;

 		memcpy(&tmp16, mc->ptr, 2);
 		mc->ptr += 2;

 		cf->can_id = le16_to_cpu(tmp16 >> 5);
 	}

 	cf->can_dlc = get_can_dlc(rec_len);

 	/* first data packet timestamp is a word */
 	if (pcan_usb_decode_ts(mc, !mc->rec_data_idx))
 		goto decode_failed;

 	/* read data */
 	memset(cf->data, 0x0, sizeof(cf->data));
 	if (status_len & PCAN_USB_STATUSLEN_RTR) {
 		cf->can_id |= CAN_RTR_FLAG;
 	} else {
 		if ((mc->ptr + rec_len) > mc->end)
 			goto decode_failed;

 		memcpy(cf->data, mc->ptr, cf->can_dlc);
 		mc->ptr += rec_len;
 	}

 	/* convert timestamp into kernel time */
 	peak_usb_get_ts_tv(&mc->pdev->time_ref, mc->ts16, &tv);
 	hwts = skb_hwtstamps(skb);
 	hwts->hwtstamp = timeval_to_ktime(tv);

 	/* push the skb */
 	netif_rx(skb);

 	/* update statistics */
 	mc->netdev->stats.rx_packets++;
 	mc->netdev->stats.rx_bytes += cf->can_dlc;

 	return 0;

 decode_failed:
 	dev_kfree_skb(skb);
 	return -EINVAL;
 }

 /*
  * process incoming message
  */
 static int pcan_usb_decode_msg(struct peak_usb_device *dev, u8 *ibuf, u32 lbuf)
 {
 	struct pcan_usb_msg_context mc = {
 		.rec_cnt = ibuf[1],
 		.ptr = ibuf + PCAN_USB_MSG_HEADER_LEN,
 		.end = ibuf + lbuf,
 		.netdev = dev->netdev,
 		.pdev = container_of(dev, struct pcan_usb, dev),
 	};
 	int err;

 	for (err = 0; mc.rec_idx < mc.rec_cnt && !err; mc.rec_idx++) {
 		u8 sl = *mc.ptr++;

 		/* handle status and error frames here */
 		if (sl & PCAN_USB_STATUSLEN_INTERNAL) {
 			err = pcan_usb_decode_status(&mc, sl);
 		/* handle normal can frames here */
 		} else {
 			err = pcan_usb_decode_data(&mc, sl);
 			mc.rec_data_idx++;
 		}
 	}

 	return err;
 }

 /*
  * process any incoming buffer
  */
 static int pcan_usb_decode_buf(struct peak_usb_device *dev, struct urb *urb)
 {
 	int err = 0;

 	if (urb->actual_length > PCAN_USB_MSG_HEADER_LEN) {
 		err = pcan_usb_decode_msg(dev, urb->transfer_buffer,
 			urb->actual_length);

 	} else if (urb->actual_length > 0) {
 		netdev_err(dev->netdev, "usb message length error (%u)\n",
 			urb->actual_length);
 		err = -EINVAL;
 	}

 	return err;
 }

 /*
  * process outgoing packet
  */
 static int pcan_usb_encode_msg(struct peak_usb_device *dev, struct sk_buff *skb,
 			       u8 *obuf, size_t *size)
 {
 	struct net_device *netdev = dev->netdev;
 	struct net_device_stats *stats = &netdev->stats;
 	struct can_frame *cf = (struct can_frame *)skb->data;
 	u8 *pc;

 	obuf[0] = 2;
 	obuf[1] = 1;

 	pc = obuf + PCAN_USB_MSG_HEADER_LEN;

 	/* status/len byte */
 	*pc = cf->can_dlc;
 	if (cf->can_id & CAN_RTR_FLAG)
 		*pc |= PCAN_USB_STATUSLEN_RTR;

 	/* can id */
 	if (cf->can_id & CAN_EFF_FLAG) {
 		__le32 tmp32 = cpu_to_le32((cf->can_id & CAN_ERR_MASK) << 3);

 		*pc |= PCAN_USB_STATUSLEN_EXT_ID;
 		memcpy(++pc, &tmp32, 4);
 		pc += 4;
 	} else {
 		__le16 tmp16 = cpu_to_le16((cf->can_id & CAN_ERR_MASK) << 5);

 		memcpy(++pc, &tmp16, 2);
 		pc += 2;
 	}

 	/* can data */
 	if (!(cf->can_id & CAN_RTR_FLAG)) {
 		memcpy(pc, cf->data, cf->can_dlc);
 		pc += cf->can_dlc;
 	}

 	obuf[(*size)-1] = (u8)(stats->tx_packets & 0xff);

 	return 0;
 }

 /*
  * start interface
  */
 static int pcan_usb_start(struct peak_usb_device *dev)
 {
 	struct pcan_usb *pdev = container_of(dev, struct pcan_usb, dev);

 	/* number of bits used in timestamps read from adapter struct */
 	peak_usb_init_time_ref(&pdev->time_ref, &pcan_usb);

 	/* if revision greater than 3, can put silent mode on/off */
 	if (dev->device_rev > 3) {
 		int err;

 		err = pcan_usb_set_silent(dev,
 				dev->can.ctrlmode & CAN_CTRLMODE_LISTENONLY);
 		if (err)
 			return err;
 	}

 	return pcan_usb_set_ext_vcc(dev, 0);
 }

 static int pcan_usb_init(struct peak_usb_device *dev)
 {
 	struct pcan_usb *pdev = container_of(dev, struct pcan_usb, dev);
 	u32 serial_number;
 	int err;

 	/* initialize a timer needed to wait for hardware restart */
 	init_timer(&pdev->restart_timer);
 	pdev->restart_timer.function = pcan_usb_restart;
 	pdev->restart_timer.data = (unsigned long)dev;

 	/*
 	 * explicit use of dev_xxx() instead of netdev_xxx() here:
 	 * information displayed are related to the device itself, not
 	 * to the canx netdevice.
 	 */
 	err = pcan_usb_get_serial(dev, &serial_number);
 	if (err) {
 		dev_err(dev->netdev->dev.parent,
 			"unable to read %s serial number (err %d)\n",
 			pcan_usb.name, err);
 		return err;
 	}

 	dev_info(dev->netdev->dev.parent,
 		 "PEAK-System %s adapter hwrev %u serial %08X (%u channel)\n",
 		 pcan_usb.name, dev->device_rev, serial_number,
 		 pcan_usb.ctrl_count);

 	return 0;
 }

 /*
  * probe function for new PCAN-USB usb interface
  */
 static int pcan_usb_probe(struct usb_interface *intf)
 {
 	struct usb_host_interface *if_desc;
 	int i;

 	if_desc = intf->altsetting;

 	/* check interface endpoint addresses */
 	for (i = 0; i < if_desc->desc.bNumEndpoints; i++) {
 		struct usb_endpoint_descriptor *ep = &if_desc->endpoint[i].desc;

 		switch (ep->bEndpointAddress) {
 		case PCAN_USB_EP_CMDOUT:
 		case PCAN_USB_EP_CMDIN:
 		case PCAN_USB_EP_MSGOUT:
 		case PCAN_USB_EP_MSGIN:
 			break;
 		default:
 			return -ENODEV;
 		}
 	}

 	return 0;
 }

 /*
  * describe the PCAN-USB adapter
  */
 struct peak_usb_adapter pcan_usb = {
 	.name = "PCAN-USB",
 	.device_id = PCAN_USB_PRODUCT_ID,
 	.ctrl_count = 1,
 	.clock = {
 		.freq = PCAN_USB_CRYSTAL_HZ / 2 ,
 	},
 	.bittiming_const = {
 		.name = "pcan_usb",
 		.tseg1_min = 1,
 		.tseg1_max = 16,
 		.tseg2_min = 1,
 		.tseg2_max = 8,
 		.sjw_max = 4,
 		.brp_min = 1,
 		.brp_max = 64,
 		.brp_inc = 1,
 	},

 	/* size of device private data */
 	.sizeof_dev_private = sizeof(struct pcan_usb),

 	/* timestamps usage */
 	.ts_used_bits = 16,
 	.ts_period = 24575, /* calibration period in ts. */
 	.us_per_ts_scale = PCAN_USB_TS_US_PER_TICK, /* us=(ts*scale) */
 	.us_per_ts_shift = PCAN_USB_TS_DIV_SHIFTER, /*  >> shift     */

 	/* give here messages in/out endpoints */
 	.ep_msg_in = PCAN_USB_EP_MSGIN,
 	.ep_msg_out = {PCAN_USB_EP_MSGOUT},

 	/* size of rx/tx usb buffers */
 	.rx_buffer_size = PCAN_USB_RX_BUFFER_SIZE,
 	.tx_buffer_size = PCAN_USB_TX_BUFFER_SIZE,

 	/* device callbacks */
 	.intf_probe = pcan_usb_probe,
 	.dev_init = pcan_usb_init,
 	.dev_set_bus = pcan_usb_write_mode,
 	.dev_set_bittiming = pcan_usb_set_bittiming,
 	.dev_get_device_id = pcan_usb_get_device_id,
 	.dev_decode_buf = pcan_usb_decode_buf,
 	.dev_encode_msg = pcan_usb_encode_msg,
 	.dev_start = pcan_usb_start,
 	.dev_restart_async = pcan_usb_restart_async,
 };
	/*
	* CAN driver for PEAK System PCAN-USB adapter
	* Derived from the PCAN project file driver/src/pcan_usb.c
	*
	* Copyright (C) 2003-2010 PEAK System-Technik GmbH
	* Copyright (C) 2011-2012 Stephane Grosjean <s.grosjean@peak-system.com>
	*
	* Many thanks to Klaus Hitschler <klaus.hitschler@gmx.de>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License as published
	* by the Free Software Foundation; version 2 of the License.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*/
	#include <linux/netdevice.h>
	#include <linux/usb.h>
	#include <linux/module.h>

	#include <linux/can.h>
	#include <linux/can/dev.h>
	#include <linux/can/error.h>

	#include "pcan_usb_core.h"

	MODULE_SUPPORTED_DEVICE("PEAK-System PCAN-USB adapter");

	/* PCAN-USB Endpoints */
	#define PCAN_USB_EP_CMDOUT 1
	#define PCAN_USB_EP_CMDIN (PCAN_USB_EP_CMDOUT \| USB_DIR_IN)
	#define PCAN_USB_EP_MSGOUT 2
	#define PCAN_USB_EP_MSGIN (PCAN_USB_EP_MSGOUT \| USB_DIR_IN)

	/* PCAN-USB command struct */
	#define PCAN_USB_CMD_FUNC 0
	#define PCAN_USB_CMD_NUM 1
	#define PCAN_USB_CMD_ARGS 2
	#define PCAN_USB_CMD_ARGS_LEN 14
	#define PCAN_USB_CMD_LEN (PCAN_USB_CMD_ARGS + \
	PCAN_USB_CMD_ARGS_LEN)

	/* PCAN-USB command timeout (ms.) */
	#define PCAN_USB_COMMAND_TIMEOUT 1000

	/* PCAN-USB startup timeout (ms.) */
	#define PCAN_USB_STARTUP_TIMEOUT 10

	/* PCAN-USB rx/tx buffers size */
	#define PCAN_USB_RX_BUFFER_SIZE 64
	#define PCAN_USB_TX_BUFFER_SIZE 64

	#define PCAN_USB_MSG_HEADER_LEN 2

	/* PCAN-USB adapter internal clock (MHz) */
	#define PCAN_USB_CRYSTAL_HZ 16000000

	/* PCAN-USB USB message record status/len field */
	#define PCAN_USB_STATUSLEN_TIMESTAMP (1 << 7)
	#define PCAN_USB_STATUSLEN_INTERNAL (1 << 6)
	#define PCAN_USB_STATUSLEN_EXT_ID (1 << 5)
	#define PCAN_USB_STATUSLEN_RTR (1 << 4)
	#define PCAN_USB_STATUSLEN_DLC (0xf)

	/* PCAN-USB error flags */
	#define PCAN_USB_ERROR_TXFULL 0x01
	#define PCAN_USB_ERROR_RXQOVR 0x02
	#define PCAN_USB_ERROR_BUS_LIGHT 0x04
	#define PCAN_USB_ERROR_BUS_HEAVY 0x08
	#define PCAN_USB_ERROR_BUS_OFF 0x10
	#define PCAN_USB_ERROR_RXQEMPTY 0x20
	#define PCAN_USB_ERROR_QOVR 0x40
	#define PCAN_USB_ERROR_TXQFULL 0x80

	/* SJA1000 modes */
	#define SJA1000_MODE_NORMAL 0x00
	#define SJA1000_MODE_INIT 0x01

	/*
	* tick duration = 42.666 us =>
	* (tick_number * 44739243) >> 20 ~ (tick_number * 42666) / 1000
	* accuracy = 10^-7
	*/
	#define PCAN_USB_TS_DIV_SHIFTER 20
	#define PCAN_USB_TS_US_PER_TICK 44739243

	/* PCAN-USB messages record types */
	#define PCAN_USB_REC_ERROR 1
	#define PCAN_USB_REC_ANALOG 2
	#define PCAN_USB_REC_BUSLOAD 3
	#define PCAN_USB_REC_TS 4
	#define PCAN_USB_REC_BUSEVT 5

	/* private to PCAN-USB adapter */
	struct pcan_usb {
	struct peak_usb_device dev;
	struct peak_time_ref time_ref;
	struct timer_list restart_timer;
	};

	/* incoming message context for decoding */
	struct pcan_usb_msg_context {
	u16 ts16;
	u8 prev_ts8;
	u8 *ptr;
	u8 *end;
	u8 rec_cnt;
	u8 rec_idx;
	u8 rec_data_idx;
	struct net_device *netdev;
	struct pcan_usb *pdev;
	};

	/*
	* send a command
	*/
	static int pcan_usb_send_cmd(struct peak_usb_device dev, u8 f, u8 n, u8 p)
	{
	int err;
	int actual_length;

	/* usb device unregistered? */
	if (!(dev->state & PCAN_USB_STATE_CONNECTED))
	return 0;

	dev->cmd_buf[PCAN_USB_CMD_FUNC] = f;
	dev->cmd_buf[PCAN_USB_CMD_NUM] = n;

	if (p)
	memcpy(dev->cmd_buf + PCAN_USB_CMD_ARGS,
	p, PCAN_USB_CMD_ARGS_LEN);

	err = usb_bulk_msg(dev->udev,
	usb_sndbulkpipe(dev->udev, PCAN_USB_EP_CMDOUT),
	dev->cmd_buf, PCAN_USB_CMD_LEN, &actual_length,
	PCAN_USB_COMMAND_TIMEOUT);
	if (err)
	netdev_err(dev->netdev,
	"sending cmd f=0x%x n=0x%x failure: %d\n",
	f, n, err);
	return err;
	}

	/*
	* send a command then wait for its response
	*/
	static int pcan_usb_wait_rsp(struct peak_usb_device dev, u8 f, u8 n, u8 p)
	{
	int err;
	int actual_length;

	/* usb device unregistered? */
	if (!(dev->state & PCAN_USB_STATE_CONNECTED))
	return 0;

	/* first, send command */
	err = pcan_usb_send_cmd(dev, f, n, NULL);
	if (err)
	return err;

	err = usb_bulk_msg(dev->udev,
	usb_rcvbulkpipe(dev->udev, PCAN_USB_EP_CMDIN),
	dev->cmd_buf, PCAN_USB_CMD_LEN, &actual_length,
	PCAN_USB_COMMAND_TIMEOUT);
	if (err)
	netdev_err(dev->netdev,
	"waiting rsp f=0x%x n=0x%x failure: %d\n", f, n, err);
	else if (p)
	memcpy(p, dev->cmd_buf + PCAN_USB_CMD_ARGS,
	PCAN_USB_CMD_ARGS_LEN);

	return err;
	}

	static int pcan_usb_set_sja1000(struct peak_usb_device *dev, u8 mode)
	{
	u8 args[PCAN_USB_CMD_ARGS_LEN] = {
	[1] = mode,
	};

	return pcan_usb_send_cmd(dev, 9, 2, args);
	}

	static int pcan_usb_set_bus(struct peak_usb_device *dev, u8 onoff)
	{
	u8 args[PCAN_USB_CMD_ARGS_LEN] = {
	[0] = !!onoff,
	};

	return pcan_usb_send_cmd(dev, 3, 2, args);
	}

	static int pcan_usb_set_silent(struct peak_usb_device *dev, u8 onoff)
	{
	u8 args[PCAN_USB_CMD_ARGS_LEN] = {
	[0] = !!onoff,
	};

	return pcan_usb_send_cmd(dev, 3, 3, args);
	}

	static int pcan_usb_set_ext_vcc(struct peak_usb_device *dev, u8 onoff)
	{
	u8 args[PCAN_USB_CMD_ARGS_LEN] = {
	[0] = !!onoff,
	};

	return pcan_usb_send_cmd(dev, 10, 2, args);
	}

	/*
	* set bittiming value to can
	*/
	static int pcan_usb_set_bittiming(struct peak_usb_device *dev,
	struct can_bittiming *bt)
	{
	u8 args[PCAN_USB_CMD_ARGS_LEN];
	u8 btr0, btr1;

	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 (dev->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
	btr1 \|= 0x80;

	netdev_info(dev->netdev, "setting BTR0=0x%02x BTR1=0x%02x\n",
	btr0, btr1);

	args[0] = btr1;
	args[1] = btr0;

	return pcan_usb_send_cmd(dev, 1, 2, args);
	}

	/*
	* init/reset can
	*/
	static int pcan_usb_write_mode(struct peak_usb_device *dev, u8 onoff)
	{
	int err;

	err = pcan_usb_set_bus(dev, onoff);
	if (err)
	return err;

	if (!onoff) {
	err = pcan_usb_set_sja1000(dev, SJA1000_MODE_INIT);
	} else {
	/* the PCAN-USB needs time to init */
	set_current_state(TASK_INTERRUPTIBLE);
	schedule_timeout(msecs_to_jiffies(PCAN_USB_STARTUP_TIMEOUT));
	}

	return err;
	}

	/*
	* handle end of waiting for the device to reset
	*/
	static void pcan_usb_restart(unsigned long arg)
	{
	/* notify candev and netdev */
	peak_usb_restart_complete((struct peak_usb_device *)arg);
	}

	/*
	* handle the submission of the restart urb
	*/
	static void pcan_usb_restart_pending(struct urb *urb)
	{
	struct pcan_usb *pdev = urb->context;

	/* the PCAN-USB needs time to restart */
	mod_timer(&pdev->restart_timer,
	jiffies + msecs_to_jiffies(PCAN_USB_STARTUP_TIMEOUT));

	/* can delete usb resources */
	peak_usb_async_complete(urb);
	}

	/*
	* handle asynchronous restart
	*/
	static int pcan_usb_restart_async(struct peak_usb_device dev, struct urb urb,
	u8 *buf)
	{
	struct pcan_usb *pdev = container_of(dev, struct pcan_usb, dev);

	if (timer_pending(&pdev->restart_timer))
	return -EBUSY;

	/* set bus on */
	buf[PCAN_USB_CMD_FUNC] = 3;
	buf[PCAN_USB_CMD_NUM] = 2;
	buf[PCAN_USB_CMD_ARGS] = 1;

	usb_fill_bulk_urb(urb, dev->udev,
	usb_sndbulkpipe(dev->udev, PCAN_USB_EP_CMDOUT),
	buf, PCAN_USB_CMD_LEN,
	pcan_usb_restart_pending, pdev);

	return usb_submit_urb(urb, GFP_ATOMIC);
	}

	/*
	* read serial number from device
	*/
	static int pcan_usb_get_serial(struct peak_usb_device dev, u32 serial_number)
	{
	u8 args[PCAN_USB_CMD_ARGS_LEN];
	int err;

	err = pcan_usb_wait_rsp(dev, 6, 1, args);
	if (err) {
	netdev_err(dev->netdev, "getting serial failure: %d\n", err);
	} else if (serial_number) {
	u32 tmp32;

	memcpy(&tmp32, args, 4);
	*serial_number = le32_to_cpu(tmp32);
	}

	return err;
	}

	/*
	* read device id from device
	*/
	static int pcan_usb_get_device_id(struct peak_usb_device dev, u32 device_id)
	{
	u8 args[PCAN_USB_CMD_ARGS_LEN];
	int err;

	err = pcan_usb_wait_rsp(dev, 4, 1, args);
	if (err)
	netdev_err(dev->netdev, "getting device id failure: %d\n", err);
	else if (device_id)
	*device_id = args[0];

	return err;
	}

	/*
	* update current time ref with received timestamp
	*/
	static int pcan_usb_update_ts(struct pcan_usb_msg_context *mc)
	{
	u16 tmp16;

	if ((mc->ptr+2) > mc->end)
	return -EINVAL;

	memcpy(&tmp16, mc->ptr, 2);

	mc->ts16 = le16_to_cpu(tmp16);

	if (mc->rec_idx > 0)
	peak_usb_update_ts_now(&mc->pdev->time_ref, mc->ts16);
	else
	peak_usb_set_ts_now(&mc->pdev->time_ref, mc->ts16);

	return 0;
	}

	/*
	* decode received timestamp
	*/
	static int pcan_usb_decode_ts(struct pcan_usb_msg_context *mc, u8 first_packet)
	{
	/* only 1st packet supplies a word timestamp */
	if (first_packet) {
	u16 tmp16;

	if ((mc->ptr + 2) > mc->end)
	return -EINVAL;

	memcpy(&tmp16, mc->ptr, 2);
	mc->ptr += 2;

	mc->ts16 = le16_to_cpu(tmp16);
	mc->prev_ts8 = mc->ts16 & 0x00ff;
	} else {
	u8 ts8;

	if ((mc->ptr + 1) > mc->end)
	return -EINVAL;

	ts8 = *mc->ptr++;

	if (ts8 < mc->prev_ts8)
	mc->ts16 += 0x100;

	mc->ts16 &= 0xff00;
	mc->ts16 \|= ts8;
	mc->prev_ts8 = ts8;
	}

	return 0;
	}

	static int pcan_usb_decode_error(struct pcan_usb_msg_context *mc, u8 n,
	u8 status_len)
	{
	struct sk_buff *skb;
	struct can_frame *cf;
	struct timeval tv;
	enum can_state new_state;

	/* ignore this error until 1st ts received */
	if (n == PCAN_USB_ERROR_QOVR)
	if (!mc->pdev->time_ref.tick_count)
	return 0;

	new_state = mc->pdev->dev.can.state;

	switch (mc->pdev->dev.can.state) {
	case CAN_STATE_ERROR_ACTIVE:
	if (n & PCAN_USB_ERROR_BUS_LIGHT) {
	new_state = CAN_STATE_ERROR_WARNING;
	break;
	}

	case CAN_STATE_ERROR_WARNING:
	if (n & PCAN_USB_ERROR_BUS_HEAVY) {
	new_state = CAN_STATE_ERROR_PASSIVE;
	break;
	}
	if (n & PCAN_USB_ERROR_BUS_OFF) {
	new_state = CAN_STATE_BUS_OFF;
	break;
	}
	if (n & (PCAN_USB_ERROR_RXQOVR \| PCAN_USB_ERROR_QOVR)) {
	/*
	* trick to bypass next comparison and process other
	* errors
	*/
	new_state = CAN_STATE_MAX;
	break;
	}
	if ((n & PCAN_USB_ERROR_BUS_LIGHT) == 0) {
	/* no error (back to active state) */
	mc->pdev->dev.can.state = CAN_STATE_ERROR_ACTIVE;
	return 0;
	}
	break;

	case CAN_STATE_ERROR_PASSIVE:
	if (n & PCAN_USB_ERROR_BUS_OFF) {
	new_state = CAN_STATE_BUS_OFF;
	break;
	}
	if (n & PCAN_USB_ERROR_BUS_LIGHT) {
	new_state = CAN_STATE_ERROR_WARNING;
	break;
	}
	if (n & (PCAN_USB_ERROR_RXQOVR \| PCAN_USB_ERROR_QOVR)) {
	/*
	* trick to bypass next comparison and process other
	* errors
	*/
	new_state = CAN_STATE_MAX;
	break;
	}

	if ((n & PCAN_USB_ERROR_BUS_HEAVY) == 0) {
	/* no error (back to active state) */
	mc->pdev->dev.can.state = CAN_STATE_ERROR_ACTIVE;
	return 0;
	}
	break;

	default:
	/* do nothing waiting for restart */
	return 0;
	}

	/* donot post any error if current state didn't change */
	if (mc->pdev->dev.can.state == new_state)
	return 0;

	/* allocate an skb to store the error frame */
	skb = alloc_can_err_skb(mc->netdev, &cf);
	if (!skb)
	return -ENOMEM;

	switch (new_state) {
	case CAN_STATE_BUS_OFF:
	cf->can_id \|= CAN_ERR_BUSOFF;
	can_bus_off(mc->netdev);
	break;

	case CAN_STATE_ERROR_PASSIVE:
	cf->can_id \|= CAN_ERR_CRTL;
	cf->data[1] \|= CAN_ERR_CRTL_TX_PASSIVE \|
	CAN_ERR_CRTL_RX_PASSIVE;
	mc->pdev->dev.can.can_stats.error_passive++;
	break;

	case CAN_STATE_ERROR_WARNING:
	cf->can_id \|= CAN_ERR_CRTL;
	cf->data[1] \|= CAN_ERR_CRTL_TX_WARNING \|
	CAN_ERR_CRTL_RX_WARNING;
	mc->pdev->dev.can.can_stats.error_warning++;
	break;

	default:
	/* CAN_STATE_MAX (trick to handle other errors) */
	cf->can_id \|= CAN_ERR_CRTL;
	cf->data[1] \|= CAN_ERR_CRTL_RX_OVERFLOW;
	mc->netdev->stats.rx_over_errors++;
	mc->netdev->stats.rx_errors++;

	new_state = mc->pdev->dev.can.state;
	break;
	}

	mc->pdev->dev.can.state = new_state;

	if (status_len & PCAN_USB_STATUSLEN_TIMESTAMP) {
	struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);

	peak_usb_get_ts_tv(&mc->pdev->time_ref, mc->ts16, &tv);
	hwts->hwtstamp = timeval_to_ktime(tv);
	}

	netif_rx(skb);
	mc->netdev->stats.rx_packets++;
	mc->netdev->stats.rx_bytes += cf->can_dlc;

	return 0;
	}

	/*
	* decode non-data usb message
	*/
	static int pcan_usb_decode_status(struct pcan_usb_msg_context *mc,
	u8 status_len)
	{
	u8 rec_len = status_len & PCAN_USB_STATUSLEN_DLC;
	u8 f, n;
	int err;

	/* check whether function and number can be read */
	if ((mc->ptr + 2) > mc->end)
	return -EINVAL;

	f = mc->ptr[PCAN_USB_CMD_FUNC];
	n = mc->ptr[PCAN_USB_CMD_NUM];
	mc->ptr += PCAN_USB_CMD_ARGS;

	if (status_len & PCAN_USB_STATUSLEN_TIMESTAMP) {
	int err = pcan_usb_decode_ts(mc, !mc->rec_idx);

	if (err)
	return err;
	}

	switch (f) {
	case PCAN_USB_REC_ERROR:
	err = pcan_usb_decode_error(mc, n, status_len);
	if (err)
	return err;
	break;

	case PCAN_USB_REC_ANALOG:
	/* analog values (ignored) */
	rec_len = 2;
	break;

	case PCAN_USB_REC_BUSLOAD:
	/* bus load (ignored) */
	rec_len = 1;
	break;

	case PCAN_USB_REC_TS:
	/* only timestamp */
	if (pcan_usb_update_ts(mc))
	return -EINVAL;
	break;

	case PCAN_USB_REC_BUSEVT:
	/* error frame/bus event */
	if (n & PCAN_USB_ERROR_TXQFULL)
	netdev_dbg(mc->netdev, "device Tx queue full)\n");
	break;
	default:
	netdev_err(mc->netdev, "unexpected function %u\n", f);
	break;
	}

	if ((mc->ptr + rec_len) > mc->end)
	return -EINVAL;

	mc->ptr += rec_len;

	return 0;
	}

	/*
	* decode data usb message
	*/
	static int pcan_usb_decode_data(struct pcan_usb_msg_context *mc, u8 status_len)
	{
	u8 rec_len = status_len & PCAN_USB_STATUSLEN_DLC;
	struct sk_buff *skb;
	struct can_frame *cf;
	struct timeval tv;
	struct skb_shared_hwtstamps *hwts;

	skb = alloc_can_skb(mc->netdev, &cf);
	if (!skb)
	return -ENOMEM;

	if (status_len & PCAN_USB_STATUSLEN_EXT_ID) {
	u32 tmp32;

	if ((mc->ptr + 4) > mc->end)
	goto decode_failed;

	memcpy(&tmp32, mc->ptr, 4);
	mc->ptr += 4;

	cf->can_id = le32_to_cpu(tmp32 >> 3) \| CAN_EFF_FLAG;
	} else {
	u16 tmp16;

	if ((mc->ptr + 2) > mc->end)
	goto decode_failed;

	memcpy(&tmp16, mc->ptr, 2);
	mc->ptr += 2;

	cf->can_id = le16_to_cpu(tmp16 >> 5);
	}

	cf->can_dlc = get_can_dlc(rec_len);

	/* first data packet timestamp is a word */
	if (pcan_usb_decode_ts(mc, !mc->rec_data_idx))
	goto decode_failed;

	/* read data */
	memset(cf->data, 0x0, sizeof(cf->data));
	if (status_len & PCAN_USB_STATUSLEN_RTR) {
	cf->can_id \|= CAN_RTR_FLAG;
	} else {
	if ((mc->ptr + rec_len) > mc->end)
	goto decode_failed;

	memcpy(cf->data, mc->ptr, cf->can_dlc);
	mc->ptr += rec_len;
	}

	/* convert timestamp into kernel time */
	peak_usb_get_ts_tv(&mc->pdev->time_ref, mc->ts16, &tv);
	hwts = skb_hwtstamps(skb);
	hwts->hwtstamp = timeval_to_ktime(tv);

	/* push the skb */
	netif_rx(skb);

	/* update statistics */
	mc->netdev->stats.rx_packets++;
	mc->netdev->stats.rx_bytes += cf->can_dlc;

	return 0;

	decode_failed:
	dev_kfree_skb(skb);
	return -EINVAL;
	}

	/*
	* process incoming message
	*/
	static int pcan_usb_decode_msg(struct peak_usb_device dev, u8 ibuf, u32 lbuf)
	{
	struct pcan_usb_msg_context mc = {
	.rec_cnt = ibuf[1],
	.ptr = ibuf + PCAN_USB_MSG_HEADER_LEN,
	.end = ibuf + lbuf,
	.netdev = dev->netdev,
	.pdev = container_of(dev, struct pcan_usb, dev),
	};
	int err;

	for (err = 0; mc.rec_idx < mc.rec_cnt && !err; mc.rec_idx++) {
	u8 sl = *mc.ptr++;

	/* handle status and error frames here */
	if (sl & PCAN_USB_STATUSLEN_INTERNAL) {
	err = pcan_usb_decode_status(&mc, sl);
	/* handle normal can frames here */
	} else {
	err = pcan_usb_decode_data(&mc, sl);
	mc.rec_data_idx++;
	}
	}

	return err;
	}

	/*
	* process any incoming buffer
	*/
	static int pcan_usb_decode_buf(struct peak_usb_device dev, struct urb urb)
	{
	int err = 0;

	if (urb->actual_length > PCAN_USB_MSG_HEADER_LEN) {
	err = pcan_usb_decode_msg(dev, urb->transfer_buffer,
	urb->actual_length);

	} else if (urb->actual_length > 0) {
	netdev_err(dev->netdev, "usb message length error (%u)\n",
	urb->actual_length);
	err = -EINVAL;
	}

	return err;
	}

	/*
	* process outgoing packet
	*/
	static int pcan_usb_encode_msg(struct peak_usb_device dev, struct sk_buff skb,
	u8 obuf, size_t size)
	{
	struct net_device *netdev = dev->netdev;
	struct net_device_stats *stats = &netdev->stats;
	struct can_frame cf = (struct can_frame )skb->data;
	u8 *pc;

	obuf[0] = 2;
	obuf[1] = 1;

	pc = obuf + PCAN_USB_MSG_HEADER_LEN;

	/* status/len byte */
	*pc = cf->can_dlc;
	if (cf->can_id & CAN_RTR_FLAG)
	*pc \|= PCAN_USB_STATUSLEN_RTR;

	/* can id */
	if (cf->can_id & CAN_EFF_FLAG) {
	__le32 tmp32 = cpu_to_le32((cf->can_id & CAN_ERR_MASK) << 3);

	*pc \|= PCAN_USB_STATUSLEN_EXT_ID;
	memcpy(++pc, &tmp32, 4);
	pc += 4;
	} else {
	__le16 tmp16 = cpu_to_le16((cf->can_id & CAN_ERR_MASK) << 5);

	memcpy(++pc, &tmp16, 2);
	pc += 2;
	}

	/* can data */
	if (!(cf->can_id & CAN_RTR_FLAG)) {
	memcpy(pc, cf->data, cf->can_dlc);
	pc += cf->can_dlc;
	}

	obuf[(*size)-1] = (u8)(stats->tx_packets & 0xff);

	return 0;
	}

	/*
	* start interface
	*/
	static int pcan_usb_start(struct peak_usb_device *dev)
	{
	struct pcan_usb *pdev = container_of(dev, struct pcan_usb, dev);

	/* number of bits used in timestamps read from adapter struct */
	peak_usb_init_time_ref(&pdev->time_ref, &pcan_usb);

	/* if revision greater than 3, can put silent mode on/off */
	if (dev->device_rev > 3) {
	int err;

	err = pcan_usb_set_silent(dev,
	dev->can.ctrlmode & CAN_CTRLMODE_LISTENONLY);
	if (err)
	return err;
	}

	return pcan_usb_set_ext_vcc(dev, 0);
	}

	static int pcan_usb_init(struct peak_usb_device *dev)
	{
	struct pcan_usb *pdev = container_of(dev, struct pcan_usb, dev);
	u32 serial_number;
	int err;

	/* initialize a timer needed to wait for hardware restart */
	init_timer(&pdev->restart_timer);
	pdev->restart_timer.function = pcan_usb_restart;
	pdev->restart_timer.data = (unsigned long)dev;

	/*
	* explicit use of dev_xxx() instead of netdev_xxx() here:
	* information displayed are related to the device itself, not
	* to the canx netdevice.
	*/
	err = pcan_usb_get_serial(dev, &serial_number);
	if (err) {
	dev_err(dev->netdev->dev.parent,
	"unable to read %s serial number (err %d)\n",
	pcan_usb.name, err);
	return err;
	}

	dev_info(dev->netdev->dev.parent,
	"PEAK-System %s adapter hwrev %u serial %08X (%u channel)\n",
	pcan_usb.name, dev->device_rev, serial_number,
	pcan_usb.ctrl_count);

	return 0;
	}

	/*
	* probe function for new PCAN-USB usb interface
	*/
	static int pcan_usb_probe(struct usb_interface *intf)
	{
	struct usb_host_interface *if_desc;
	int i;

	if_desc = intf->altsetting;

	/* check interface endpoint addresses */
	for (i = 0; i < if_desc->desc.bNumEndpoints; i++) {
	struct usb_endpoint_descriptor *ep = &if_desc->endpoint[i].desc;

	switch (ep->bEndpointAddress) {
	case PCAN_USB_EP_CMDOUT:
	case PCAN_USB_EP_CMDIN:
	case PCAN_USB_EP_MSGOUT:
	case PCAN_USB_EP_MSGIN:
	break;
	default:
	return -ENODEV;
	}
	}

	return 0;
	}

	/*
	* describe the PCAN-USB adapter
	*/
	struct peak_usb_adapter pcan_usb = {
	.name = "PCAN-USB",
	.device_id = PCAN_USB_PRODUCT_ID,
	.ctrl_count = 1,
	.clock = {
	.freq = PCAN_USB_CRYSTAL_HZ / 2 ,
	},
	.bittiming_const = {
	.name = "pcan_usb",
	.tseg1_min = 1,
	.tseg1_max = 16,
	.tseg2_min = 1,
	.tseg2_max = 8,
	.sjw_max = 4,
	.brp_min = 1,
	.brp_max = 64,
	.brp_inc = 1,
	},

	/* size of device private data */
	.sizeof_dev_private = sizeof(struct pcan_usb),

	/* timestamps usage */
	.ts_used_bits = 16,
	.ts_period = 24575, /* calibration period in ts. */
	.us_per_ts_scale = PCAN_USB_TS_US_PER_TICK, /* us=(tsscale) /
	.us_per_ts_shift = PCAN_USB_TS_DIV_SHIFTER, /* >> shift */

	/* give here messages in/out endpoints */
	.ep_msg_in = PCAN_USB_EP_MSGIN,
	.ep_msg_out = {PCAN_USB_EP_MSGOUT},

	/* size of rx/tx usb buffers */
	.rx_buffer_size = PCAN_USB_RX_BUFFER_SIZE,
	.tx_buffer_size = PCAN_USB_TX_BUFFER_SIZE,

	/* device callbacks */
	.intf_probe = pcan_usb_probe,
	.dev_init = pcan_usb_init,
	.dev_set_bus = pcan_usb_write_mode,
	.dev_set_bittiming = pcan_usb_set_bittiming,
	.dev_get_device_id = pcan_usb_get_device_id,
	.dev_decode_buf = pcan_usb_decode_buf,
	.dev_encode_msg = pcan_usb_encode_msg,
	.dev_start = pcan_usb_start,
	.dev_restart_async = pcan_usb_restart_async,
	};