can: usb_8dev: Add support for USB2CAN interface from 8 devices

Add device driver for USB2CAN interface from "8 devices" (http://www.8devices.com).

changes since v10:
* small cleanups

changes since v9:
* fixed syslog messages
* fixed crc error number
* increased MAX_RX_URBS and MAX_TX_URBS

changes since v8:
* remove all sysfs files

changes since v7:
* add sysfs documentation
* fix minor styling issue
* fixed can state for passive mode
* changed handling for crc errors

changes since v6:
* changed some variable types to big endian equivalent
* small cleanups

changes since v5:
* unlock mutex on error

changes since v4:
* removed FSF address
* renamed struct usb_8dev
* removed unused variable free_slots
* replaced some _to_cpu functions with pointer equivalent
* fix return value for usb_8dev_set_mode
* handle can errors with separate function
* fix overrun error handling
* rewrite error handling for usb_8dev_start_xmit
* fix urb submit in usb_8dev_start
* various small fixes

Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Tested-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Bernd Krumboeck <krumboeck@universalnet.at>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

3 files changed, 1029 insertions, 0 deletions

diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
index acba33d1e2b0..fc96a3d83ebe 100644
--- a/drivers/net/can/usb/Kconfig
+++ b/drivers/net/can/usb/Kconfig
@@ -48,4 +48,10 @@ config CAN_PEAK_USB
           This driver supports the PCAN-USB and PCAN-USB Pro adapters
           from PEAK-System Technik (http://www.peak-system.com).
 
+config CAN_8DEV_USB
+        tristate "8 devices USB2CAN interface"
+        ---help---
+          This driver supports the USB2CAN interface
+          from 8 devices (http://www.8devices.com).
+
 endmenu
diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
index 80a2ee41fd61..becef460a91a 100644
--- a/drivers/net/can/usb/Makefile
+++ b/drivers/net/can/usb/Makefile
@@ -6,5 +6,6 @@ obj-$(CONFIG_CAN_EMS_USB) += ems_usb.o
 obj-$(CONFIG_CAN_ESD_USB2) += esd_usb2.o
 obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb.o
 obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
+obj-$(CONFIG_CAN_8DEV_USB) += usb_8dev.o
 
 ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
diff --git a/drivers/net/can/usb/usb_8dev.c b/drivers/net/can/usb/usb_8dev.c
new file mode 100644
index 000000000000..a9e73fa4ad0f
--- /dev/null
+++ b/drivers/net/can/usb/usb_8dev.c
@@ -0,0 +1,1022 @@
+/*
+ * CAN driver for "8 devices" USB2CAN converter
+ *
+ * Copyright (C) 2012 Bernd Krumboeck (krumboeck@universalnet.at)
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.
+ *
+ * This driver is inspired by the 3.2.0 version of drivers/net/can/usb/ems_usb.c
+ * and drivers/net/can/usb/esd_usb2.c
+ *
+ * Many thanks to Gerhard Bertelsmann (info@gerhard-bertelsmann.de)
+ * for testing and fixing this driver. Also many thanks to "8 devices",
+ * who were very cooperative and answered my questions.
+ */
+
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/usb.h>
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+
+/* driver constants */
+#define MAX_RX_URBS                     20
+#define MAX_TX_URBS                     20
+#define RX_BUFFER_SIZE                  64
+
+/* vendor and product id */
+#define USB_8DEV_VENDOR_ID              0x0483
+#define USB_8DEV_PRODUCT_ID             0x1234
+
+/* endpoints */
+enum usb_8dev_endpoint {
+        USB_8DEV_ENDP_DATA_RX = 1,
+        USB_8DEV_ENDP_DATA_TX,
+        USB_8DEV_ENDP_CMD_RX,
+        USB_8DEV_ENDP_CMD_TX
+};
+
+/* device CAN clock */
+#define USB_8DEV_ABP_CLOCK              32000000
+
+/* setup flags */
+#define USB_8DEV_SILENT                 0x01
+#define USB_8DEV_LOOPBACK               0x02
+#define USB_8DEV_DISABLE_AUTO_RESTRANS  0x04
+#define USB_8DEV_STATUS_FRAME           0x08
+
+/* commands */
+enum usb_8dev_cmd {
+        USB_8DEV_RESET = 1,
+        USB_8DEV_OPEN,
+        USB_8DEV_CLOSE,
+        USB_8DEV_SET_SPEED,
+        USB_8DEV_SET_MASK_FILTER,
+        USB_8DEV_GET_STATUS,
+        USB_8DEV_GET_STATISTICS,
+        USB_8DEV_GET_SERIAL,
+        USB_8DEV_GET_SOFTW_VER,
+        USB_8DEV_GET_HARDW_VER,
+        USB_8DEV_RESET_TIMESTAMP,
+        USB_8DEV_GET_SOFTW_HARDW_VER
+};
+
+/* command options */
+#define USB_8DEV_BAUD_MANUAL            0x09
+#define USB_8DEV_CMD_START              0x11
+#define USB_8DEV_CMD_END                0x22
+
+#define USB_8DEV_CMD_SUCCESS            0
+#define USB_8DEV_CMD_ERROR              255
+
+#define USB_8DEV_CMD_TIMEOUT            1000
+
+/* frames */
+#define USB_8DEV_DATA_START             0x55
+#define USB_8DEV_DATA_END               0xAA
+
+#define USB_8DEV_TYPE_CAN_FRAME         0
+#define USB_8DEV_TYPE_ERROR_FRAME       3
+
+#define USB_8DEV_EXTID                  0x01
+#define USB_8DEV_RTR                    0x02
+#define USB_8DEV_ERR_FLAG               0x04
+
+/* status */
+#define USB_8DEV_STATUSMSG_OK           0x00  /* Normal condition. */
+#define USB_8DEV_STATUSMSG_OVERRUN      0x01  /* Overrun occured when sending */
+#define USB_8DEV_STATUSMSG_BUSLIGHT     0x02  /* Error counter has reached 96 */
+#define USB_8DEV_STATUSMSG_BUSHEAVY     0x03  /* Error count. has reached 128 */
+#define USB_8DEV_STATUSMSG_BUSOFF       0x04  /* Device is in BUSOFF */
+#define USB_8DEV_STATUSMSG_STUFF        0x20  /* Stuff Error */
+#define USB_8DEV_STATUSMSG_FORM         0x21  /* Form Error */
+#define USB_8DEV_STATUSMSG_ACK          0x23  /* Ack Error */
+#define USB_8DEV_STATUSMSG_BIT0         0x24  /* Bit1 Error */
+#define USB_8DEV_STATUSMSG_BIT1         0x25  /* Bit0 Error */
+#define USB_8DEV_STATUSMSG_CRC          0x27  /* CRC Error */
+
+#define USB_8DEV_RP_MASK                0x7F  /* Mask for Receive Error Bit */
+
+
+/* table of devices that work with this driver */
+static const struct usb_device_id usb_8dev_table[] = {
+        { USB_DEVICE(USB_8DEV_VENDOR_ID, USB_8DEV_PRODUCT_ID) },
+        { }                                     /* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, usb_8dev_table);
+
+struct usb_8dev_tx_urb_context {
+        struct usb_8dev_priv *priv;
+
+        u32 echo_index;
+        u8 dlc;
+};
+
+/* Structure to hold all of our device specific stuff */
+struct usb_8dev_priv {
+        struct can_priv can; /* must be the first member */
+
+        struct sk_buff *echo_skb[MAX_TX_URBS];
+
+        struct usb_device *udev;
+        struct net_device *netdev;
+
+        atomic_t active_tx_urbs;
+        struct usb_anchor tx_submitted;
+        struct usb_8dev_tx_urb_context tx_contexts[MAX_TX_URBS];
+
+        struct usb_anchor rx_submitted;
+
+        struct can_berr_counter bec;
+
+        u8 *cmd_msg_buffer;
+
+        struct mutex usb_8dev_cmd_lock;
+
+};
+
+/* tx frame */
+struct __packed usb_8dev_tx_msg {
+        u8 begin;
+        u8 flags;       /* RTR and EXT_ID flag */
+        __be32 id;      /* upper 3 bits not used */
+        u8 dlc;         /* data length code 0-8 bytes */
+        u8 data[8];     /* 64-bit data */
+        u8 end;
+};
+
+/* rx frame */
+struct __packed usb_8dev_rx_msg {
+        u8 begin;
+        u8 type;                /* frame type */
+        u8 flags;               /* RTR and EXT_ID flag */
+        __be32 id;              /* upper 3 bits not used */
+        u8 dlc;                 /* data length code 0-8 bytes */
+        u8 data[8];             /* 64-bit data */
+        __be32 timestamp;       /* 32-bit timestamp */
+        u8 end;
+};
+
+/* command frame */
+struct __packed usb_8dev_cmd_msg {
+        u8 begin;
+        u8 channel;     /* unkown - always 0 */
+        u8 command;     /* command to execute */
+        u8 opt1;        /* optional parameter / return value */
+        u8 opt2;        /* optional parameter 2 */
+        u8 data[10];    /* optional parameter and data */
+        u8 end;
+};
+
+static int usb_8dev_send_cmd_msg(struct usb_8dev_priv *priv, u8 *msg, int size)
+{
+        int actual_length;
+
+        return usb_bulk_msg(priv->udev,
+                            usb_sndbulkpipe(priv->udev, USB_8DEV_ENDP_CMD_TX),
+                            msg, size, &actual_length, USB_8DEV_CMD_TIMEOUT);
+}
+
+static int usb_8dev_wait_cmd_msg(struct usb_8dev_priv *priv, u8 *msg, int size,
+                                int *actual_length)
+{
+        return usb_bulk_msg(priv->udev,
+                            usb_rcvbulkpipe(priv->udev, USB_8DEV_ENDP_CMD_RX),
+                            msg, size, actual_length, USB_8DEV_CMD_TIMEOUT);
+}
+
+/* Send command to device and receive result.
+ * Command was successful when opt1 = 0.
+ */
+static int usb_8dev_send_cmd(struct usb_8dev_priv *priv,
+                             struct usb_8dev_cmd_msg *out,
+                             struct usb_8dev_cmd_msg *in)
+{
+        int err;
+        int num_bytes_read;
+        struct net_device *netdev;
+
+        netdev = priv->netdev;
+
+        out->begin = USB_8DEV_CMD_START;
+        out->end = USB_8DEV_CMD_END;
+
+        mutex_lock(&priv->usb_8dev_cmd_lock);
+
+        memcpy(priv->cmd_msg_buffer, out,
+                sizeof(struct usb_8dev_cmd_msg));
+
+        err = usb_8dev_send_cmd_msg(priv, priv->cmd_msg_buffer,
+                                    sizeof(struct usb_8dev_cmd_msg));
+        if (err < 0) {
+                netdev_err(netdev, "sending command message failed\n");
+                goto failed;
+        }
+
+        err = usb_8dev_wait_cmd_msg(priv, priv->cmd_msg_buffer,
+                                    sizeof(struct usb_8dev_cmd_msg),
+                                    &num_bytes_read);
+        if (err < 0) {
+                netdev_err(netdev, "no command message answer\n");
+                goto failed;
+        }
+
+        memcpy(in, priv->cmd_msg_buffer, sizeof(struct usb_8dev_cmd_msg));
+
+        if (in->begin != USB_8DEV_CMD_START || in->end != USB_8DEV_CMD_END ||
+                        num_bytes_read != 16 || in->opt1 != 0)
+                err = -EPROTO;
+
+failed:
+        mutex_unlock(&priv->usb_8dev_cmd_lock);
+        return err;
+}
+
+/* Send open command to device */
+static int usb_8dev_cmd_open(struct usb_8dev_priv *priv)
+{
+        struct can_bittiming *bt = &priv->can.bittiming;
+        struct usb_8dev_cmd_msg outmsg;
+        struct usb_8dev_cmd_msg inmsg;
+        u32 ctrlmode = priv->can.ctrlmode;
+        u32 flags = USB_8DEV_STATUS_FRAME;
+        __be32 beflags;
+        __be16 bebrp;
+
+        memset(&outmsg, 0, sizeof(outmsg));
+        outmsg.command = USB_8DEV_OPEN;
+        outmsg.opt1 = USB_8DEV_BAUD_MANUAL;
+        outmsg.data[0] = bt->prop_seg + bt->phase_seg1;
+        outmsg.data[1] = bt->phase_seg2;
+        outmsg.data[2] = bt->sjw;
+
+        /* BRP */
+        bebrp = cpu_to_be16((u16)bt->brp);
+        memcpy(&outmsg.data[3], &bebrp, sizeof(bebrp));
+
+        /* flags */
+        if (ctrlmode & CAN_CTRLMODE_LOOPBACK)
+                flags |= USB_8DEV_LOOPBACK;
+        if (ctrlmode & CAN_CTRLMODE_LISTENONLY)
+                flags |= USB_8DEV_SILENT;
+        if (ctrlmode & CAN_CTRLMODE_ONE_SHOT)
+                flags |= USB_8DEV_DISABLE_AUTO_RESTRANS;
+
+        beflags = cpu_to_be32(flags);
+        memcpy(&outmsg.data[5], &beflags, sizeof(beflags));
+
+        return usb_8dev_send_cmd(priv, &outmsg, &inmsg);
+}
+
+/* Send close command to device */
+static int usb_8dev_cmd_close(struct usb_8dev_priv *priv)
+{
+        struct usb_8dev_cmd_msg inmsg;
+        struct usb_8dev_cmd_msg outmsg = {
+                .channel = 0,
+                .command = USB_8DEV_CLOSE,
+                .opt1 = 0,
+                .opt2 = 0
+        };
+
+        return usb_8dev_send_cmd(priv, &outmsg, &inmsg);
+}
+
+/* Get firmware and hardware version */
+static int usb_8dev_cmd_version(struct usb_8dev_priv *priv, u32 *res)
+{
+        struct usb_8dev_cmd_msg inmsg;
+        struct usb_8dev_cmd_msg outmsg = {
+                .channel = 0,
+                .command = USB_8DEV_GET_SOFTW_HARDW_VER,
+                .opt1 = 0,
+                .opt2 = 0
+        };
+
+        int err = usb_8dev_send_cmd(priv, &outmsg, &inmsg);
+        if (err)
+                return err;
+
+        *res = be32_to_cpup((__be32 *)inmsg.data);
+
+        return err;
+}
+
+/* Set network device mode
+ *
+ * Maybe we should leave this function empty, because the device
+ * set mode variable with open command.
+ */
+static int usb_8dev_set_mode(struct net_device *netdev, enum can_mode mode)
+{
+        struct usb_8dev_priv *priv = netdev_priv(netdev);
+        int err = 0;
+
+        switch (mode) {
+        case CAN_MODE_START:
+                err = usb_8dev_cmd_open(priv);
+                if (err)
+                        netdev_warn(netdev, "couldn't start device");
+                break;
+
+        default:
+                return -EOPNOTSUPP;
+        }
+
+        return err;
+}
+
+/* Read error/status frames */
+static void usb_8dev_rx_err_msg(struct usb_8dev_priv *priv,
+                                struct usb_8dev_rx_msg *msg)
+{
+        struct can_frame *cf;
+        struct sk_buff *skb;
+        struct net_device_stats *stats = &priv->netdev->stats;
+
+        /* Error message:
+         * byte 0: Status
+         * byte 1: bit   7: Receive Passive
+         * byte 1: bit 0-6: Receive Error Counter
+         * byte 2: Transmit Error Counter
+         * byte 3: Always 0 (maybe reserved for future use)
+         */
+
+        u8 state = msg->data[0];
+        u8 rxerr = msg->data[1] & USB_8DEV_RP_MASK;
+        u8 txerr = msg->data[2];
+        int rx_errors = 0;
+        int tx_errors = 0;
+
+        skb = alloc_can_err_skb(priv->netdev, &cf);
+        if (!skb)
+                return;
+
+        switch (state) {
+        case USB_8DEV_STATUSMSG_OK:
+                priv->can.state = CAN_STATE_ERROR_ACTIVE;
+                cf->can_id |= CAN_ERR_PROT;
+                cf->data[2] = CAN_ERR_PROT_ACTIVE;
+                break;
+        case USB_8DEV_STATUSMSG_BUSOFF:
+                priv->can.state = CAN_STATE_BUS_OFF;
+                cf->can_id |= CAN_ERR_BUSOFF;
+                can_bus_off(priv->netdev);
+                break;
+        case USB_8DEV_STATUSMSG_OVERRUN:
+        case USB_8DEV_STATUSMSG_BUSLIGHT:
+        case USB_8DEV_STATUSMSG_BUSHEAVY:
+                cf->can_id |= CAN_ERR_CRTL;
+                break;
+        default:
+                priv->can.state = CAN_STATE_ERROR_WARNING;
+                cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
+                priv->can.can_stats.bus_error++;
+                break;
+        }
+
+        switch (state) {
+        case USB_8DEV_STATUSMSG_OK:
+        case USB_8DEV_STATUSMSG_BUSOFF:
+                break;
+        case USB_8DEV_STATUSMSG_ACK:
+                cf->can_id |= CAN_ERR_ACK;
+                tx_errors = 1;
+                break;
+        case USB_8DEV_STATUSMSG_CRC:
+                cf->data[2] |= CAN_ERR_PROT_UNSPEC;
+                cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ |
+                               CAN_ERR_PROT_LOC_CRC_DEL;
+                rx_errors = 1;
+                break;
+        case USB_8DEV_STATUSMSG_BIT0:
+                cf->data[2] |= CAN_ERR_PROT_BIT0;
+                tx_errors = 1;
+                break;
+        case USB_8DEV_STATUSMSG_BIT1:
+                cf->data[2] |= CAN_ERR_PROT_BIT1;
+                tx_errors = 1;
+                break;
+        case USB_8DEV_STATUSMSG_FORM:
+                cf->data[2] |= CAN_ERR_PROT_FORM;
+                rx_errors = 1;
+                break;
+        case USB_8DEV_STATUSMSG_STUFF:
+                cf->data[2] |= CAN_ERR_PROT_STUFF;
+                rx_errors = 1;
+                break;
+        case USB_8DEV_STATUSMSG_OVERRUN:
+                cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+                stats->rx_over_errors++;
+                rx_errors = 1;
+                break;
+        case USB_8DEV_STATUSMSG_BUSLIGHT:
+                priv->can.state = CAN_STATE_ERROR_WARNING;
+                cf->data[1] = (txerr > rxerr) ?
+                        CAN_ERR_CRTL_TX_WARNING :
+                        CAN_ERR_CRTL_RX_WARNING;
+                priv->can.can_stats.error_warning++;
+                break;
+        case USB_8DEV_STATUSMSG_BUSHEAVY:
+                priv->can.state = CAN_STATE_ERROR_PASSIVE;
+                cf->data[1] = (txerr > rxerr) ?
+                        CAN_ERR_CRTL_TX_PASSIVE :
+                        CAN_ERR_CRTL_RX_PASSIVE;
+                priv->can.can_stats.error_passive++;
+                break;
+        default:
+                netdev_warn(priv->netdev,
+                            "Unknown status/error message (%d)\n", state);
+                break;
+        }
+
+        if (tx_errors) {
+                cf->data[2] |= CAN_ERR_PROT_TX;
+                stats->tx_errors++;
+        }
+
+        if (rx_errors)
+                stats->rx_errors++;
+
+        cf->data[6] = txerr;
+        cf->data[7] = rxerr;
+
+        priv->bec.txerr = txerr;
+        priv->bec.rxerr = rxerr;
+
+        netif_rx(skb);
+
+        stats->rx_packets++;
+        stats->rx_bytes += cf->can_dlc;
+}
+
+/* Read data and status frames */
+static void usb_8dev_rx_can_msg(struct usb_8dev_priv *priv,
+                                struct usb_8dev_rx_msg *msg)
+{
+        struct can_frame *cf;
+        struct sk_buff *skb;
+        struct net_device_stats *stats = &priv->netdev->stats;
+
+        if (msg->type == USB_8DEV_TYPE_ERROR_FRAME &&
+                   msg->flags == USB_8DEV_ERR_FLAG) {
+                usb_8dev_rx_err_msg(priv, msg);
+        } else if (msg->type == USB_8DEV_TYPE_CAN_FRAME) {
+                skb = alloc_can_skb(priv->netdev, &cf);
+                if (!skb)
+                        return;
+
+                cf->can_id = be32_to_cpu(msg->id);
+                cf->can_dlc = get_can_dlc(msg->dlc & 0xF);
+
+                if (msg->flags & USB_8DEV_EXTID)
+                        cf->can_id |= CAN_EFF_FLAG;
+
+                if (msg->flags & USB_8DEV_RTR)
+                        cf->can_id |= CAN_RTR_FLAG;
+                else
+                        memcpy(cf->data, msg->data, cf->can_dlc);
+
+                netif_rx(skb);
+
+                stats->rx_packets++;
+                stats->rx_bytes += cf->can_dlc;
+        } else {
+                netdev_warn(priv->netdev, "frame type %d unknown",
+                         msg->type);
+        }
+
+}
+
+/* Callback for reading data from device
+ *
+ * Check urb status, call read function and resubmit urb read operation.
+ */
+static void usb_8dev_read_bulk_callback(struct urb *urb)
+{
+        struct usb_8dev_priv *priv = urb->context;
+        struct net_device *netdev;
+        int retval;
+        int pos = 0;
+
+        netdev = priv->netdev;
+
+        if (!netif_device_present(netdev))
+                return;
+
+        switch (urb->status) {
+        case 0: /* success */
+                break;
+
+        case -ENOENT:
+        case -ESHUTDOWN:
+                return;
+
+        default:
+                netdev_info(netdev, "Rx URB aborted (%d)\n",
+                         urb->status);
+                goto resubmit_urb;
+        }
+
+        while (pos < urb->actual_length) {
+                struct usb_8dev_rx_msg *msg;
+
+                if (pos + sizeof(struct usb_8dev_rx_msg) > urb->actual_length) {
+                        netdev_err(priv->netdev, "format error\n");
+                        break;
+                }
+
+                msg = (struct usb_8dev_rx_msg *)(urb->transfer_buffer + pos);
+                usb_8dev_rx_can_msg(priv, msg);
+
+                pos += sizeof(struct usb_8dev_rx_msg);
+        }
+
+resubmit_urb:
+        usb_fill_bulk_urb(urb, priv->udev,
+                          usb_rcvbulkpipe(priv->udev, USB_8DEV_ENDP_DATA_RX),
+                          urb->transfer_buffer, RX_BUFFER_SIZE,
+                          usb_8dev_read_bulk_callback, priv);
+
+        retval = usb_submit_urb(urb, GFP_ATOMIC);
+
+        if (retval == -ENODEV)
+                netif_device_detach(netdev);
+        else if (retval)
+                netdev_err(netdev,
+                        "failed resubmitting read bulk urb: %d\n", retval);
+}
+
+/* Callback handler for write operations
+ *
+ * Free allocated buffers, check transmit status and
+ * calculate statistic.
+ */
+static void usb_8dev_write_bulk_callback(struct urb *urb)
+{
+        struct usb_8dev_tx_urb_context *context = urb->context;
+        struct usb_8dev_priv *priv;
+        struct net_device *netdev;
+
+        BUG_ON(!context);
+
+        priv = context->priv;
+        netdev = priv->netdev;
+
+        /* free up our allocated buffer */
+        usb_free_coherent(urb->dev, urb->transfer_buffer_length,
+                          urb->transfer_buffer, urb->transfer_dma);
+
+        atomic_dec(&priv->active_tx_urbs);
+
+        if (!netif_device_present(netdev))
+                return;
+
+        if (urb->status)
+                netdev_info(netdev, "Tx URB aborted (%d)\n",
+                         urb->status);
+
+        netdev->stats.tx_packets++;
+        netdev->stats.tx_bytes += context->dlc;
+
+        can_get_echo_skb(netdev, context->echo_index);
+
+        /* Release context */
+        context->echo_index = MAX_TX_URBS;
+
+        netif_wake_queue(netdev);
+}
+
+/* Send data to device */
+static netdev_tx_t usb_8dev_start_xmit(struct sk_buff *skb,
+                                      struct net_device *netdev)
+{
+        struct usb_8dev_priv *priv = netdev_priv(netdev);
+        struct net_device_stats *stats = &netdev->stats;
+        struct can_frame *cf = (struct can_frame *) skb->data;
+        struct usb_8dev_tx_msg *msg;
+        struct urb *urb;
+        struct usb_8dev_tx_urb_context *context = NULL;
+        u8 *buf;
+        int i, err;
+        size_t size = sizeof(struct usb_8dev_tx_msg);
+
+        if (can_dropped_invalid_skb(netdev, skb))
+                return NETDEV_TX_OK;
+
+        /* create a URB, and a buffer for it, and copy the data to the URB */
+        urb = usb_alloc_urb(0, GFP_ATOMIC);
+        if (!urb) {
+                netdev_err(netdev, "No memory left for URBs\n");
+                goto nomem;
+        }
+
+        buf = usb_alloc_coherent(priv->udev, size, GFP_ATOMIC,
+                                 &urb->transfer_dma);
+        if (!buf) {
+                netdev_err(netdev, "No memory left for USB buffer\n");
+                goto nomembuf;
+        }
+
+        memset(buf, 0, size);
+
+        msg = (struct usb_8dev_tx_msg *)buf;
+        msg->begin = USB_8DEV_DATA_START;
+        msg->flags = 0x00;
+
+        if (cf->can_id & CAN_RTR_FLAG)
+                msg->flags |= USB_8DEV_RTR;
+
+        if (cf->can_id & CAN_EFF_FLAG)
+                msg->flags |= USB_8DEV_EXTID;
+
+        msg->id = cpu_to_be32(cf->can_id & CAN_ERR_MASK);
+        msg->dlc = cf->can_dlc;
+        memcpy(msg->data, cf->data, cf->can_dlc);
+        msg->end = USB_8DEV_DATA_END;
+
+        for (i = 0; i < MAX_TX_URBS; i++) {
+                if (priv->tx_contexts[i].echo_index == MAX_TX_URBS) {
+                        context = &priv->tx_contexts[i];
+                        break;
+                }
+        }
+
+        /* May never happen! When this happens we'd more URBs in flight as
+         * allowed (MAX_TX_URBS).
+         */
+        if (!context)
+                goto nofreecontext;
+
+        context->priv = priv;
+        context->echo_index = i;
+        context->dlc = cf->can_dlc;
+
+        usb_fill_bulk_urb(urb, priv->udev,
+                          usb_sndbulkpipe(priv->udev, USB_8DEV_ENDP_DATA_TX),
+                          buf, size, usb_8dev_write_bulk_callback, context);
+        urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+        usb_anchor_urb(urb, &priv->tx_submitted);
+
+        can_put_echo_skb(skb, netdev, context->echo_index);
+
+        atomic_inc(&priv->active_tx_urbs);
+
+        err = usb_submit_urb(urb, GFP_ATOMIC);
+        if (unlikely(err))
+                goto failed;
+        else if (atomic_read(&priv->active_tx_urbs) >= MAX_TX_URBS)
+                /* Slow down tx path */
+                netif_stop_queue(netdev);
+
+        /* Release our reference to this URB, the USB core will eventually free
+         * it entirely.
+         */
+        usb_free_urb(urb);
+
+        return NETDEV_TX_OK;
+
+nofreecontext:
+        usb_unanchor_urb(urb);
+        usb_free_coherent(priv->udev, size, buf, urb->transfer_dma);
+
+        netdev_warn(netdev, "couldn't find free context");
+
+        return NETDEV_TX_BUSY;
+
+failed:
+        can_free_echo_skb(netdev, context->echo_index);
+
+        usb_unanchor_urb(urb);
+        usb_free_coherent(priv->udev, size, buf, urb->transfer_dma);
+
+        atomic_dec(&priv->active_tx_urbs);
+
+        if (err == -ENODEV)
+                netif_device_detach(netdev);
+        else
+                netdev_warn(netdev, "failed tx_urb %d\n", err);
+
+nomembuf:
+        usb_free_urb(urb);
+
+nomem:
+        dev_kfree_skb(skb);
+        stats->tx_dropped++;
+
+        return NETDEV_TX_OK;
+}
+
+static int usb_8dev_get_berr_counter(const struct net_device *netdev,
+                                     struct can_berr_counter *bec)
+{
+        struct usb_8dev_priv *priv = netdev_priv(netdev);
+
+        bec->txerr = priv->bec.txerr;
+        bec->rxerr = priv->bec.rxerr;
+
+        return 0;
+}
+
+/* Start USB device */
+static int usb_8dev_start(struct usb_8dev_priv *priv)
+{
+        struct net_device *netdev = priv->netdev;
+        int err, i;
+
+        for (i = 0; i < MAX_RX_URBS; i++) {
+                struct urb *urb = NULL;
+                u8 *buf;
+
+                /* create a URB, and a buffer for it */
+                urb = usb_alloc_urb(0, GFP_KERNEL);
+                if (!urb) {
+                        netdev_err(netdev, "No memory left for URBs\n");
+                        err = -ENOMEM;
+                        break;
+                }
+
+                buf = usb_alloc_coherent(priv->udev, RX_BUFFER_SIZE, GFP_KERNEL,
+                                         &urb->transfer_dma);
+                if (!buf) {
+                        netdev_err(netdev, "No memory left for USB buffer\n");
+                        usb_free_urb(urb);
+                        err = -ENOMEM;
+                        break;
+                }
+
+                usb_fill_bulk_urb(urb, priv->udev,
+                                  usb_rcvbulkpipe(priv->udev,
+                                                  USB_8DEV_ENDP_DATA_RX),
+                                  buf, RX_BUFFER_SIZE,
+                                  usb_8dev_read_bulk_callback, priv);
+                urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+                usb_anchor_urb(urb, &priv->rx_submitted);
+
+                err = usb_submit_urb(urb, GFP_KERNEL);
+                if (err) {
+                        usb_unanchor_urb(urb);
+                        usb_free_coherent(priv->udev, RX_BUFFER_SIZE, buf,
+                                          urb->transfer_dma);
+                        break;
+                }
+
+                /* Drop reference, USB core will take care of freeing it */
+                usb_free_urb(urb);
+        }
+
+        /* Did we submit any URBs */
+        if (i == 0) {
+                netdev_warn(netdev, "couldn't setup read URBs\n");
+                return err;
+        }
+
+        /* Warn if we've couldn't transmit all the URBs */
+        if (i < MAX_RX_URBS)
+                netdev_warn(netdev, "rx performance may be slow\n");
+
+        err = usb_8dev_cmd_open(priv);
+        if (err)
+                goto failed;
+
+        priv->can.state = CAN_STATE_ERROR_ACTIVE;
+
+        return 0;
+
+failed:
+        if (err == -ENODEV)
+                netif_device_detach(priv->netdev);
+
+        netdev_warn(netdev, "couldn't submit control: %d\n", err);
+
+        return err;
+}
+
+/* Open USB device */
+static int usb_8dev_open(struct net_device *netdev)
+{
+        struct usb_8dev_priv *priv = netdev_priv(netdev);
+        int err;
+
+        /* common open */
+        err = open_candev(netdev);
+        if (err)
+                return err;
+
+        /* finally start device */
+        err = usb_8dev_start(priv);
+        if (err) {
+                if (err == -ENODEV)
+                        netif_device_detach(priv->netdev);
+
+                netdev_warn(netdev, "couldn't start device: %d\n",
+                         err);
+
+                close_candev(netdev);
+
+                return err;
+        }
+
+        netif_start_queue(netdev);
+
+        return 0;
+}
+
+static void unlink_all_urbs(struct usb_8dev_priv *priv)
+{
+        int i;
+
+        usb_kill_anchored_urbs(&priv->rx_submitted);
+
+        usb_kill_anchored_urbs(&priv->tx_submitted);
+        atomic_set(&priv->active_tx_urbs, 0);
+
+        for (i = 0; i < MAX_TX_URBS; i++)
+                priv->tx_contexts[i].echo_index = MAX_TX_URBS;
+}
+
+/* Close USB device */
+static int usb_8dev_close(struct net_device *netdev)
+{
+        struct usb_8dev_priv *priv = netdev_priv(netdev);
+        int err = 0;
+
+        /* Send CLOSE command to CAN controller */
+        err = usb_8dev_cmd_close(priv);
+        if (err)
+                netdev_warn(netdev, "couldn't stop device");
+
+        priv->can.state = CAN_STATE_STOPPED;
+
+        netif_stop_queue(netdev);
+
+        /* Stop polling */
+        unlink_all_urbs(priv);
+
+        close_candev(netdev);
+
+        return err;
+}
+
+static const struct net_device_ops usb_8dev_netdev_ops = {
+        .ndo_open = usb_8dev_open,
+        .ndo_stop = usb_8dev_close,
+        .ndo_start_xmit = usb_8dev_start_xmit,
+};
+
+static const struct can_bittiming_const usb_8dev_bittiming_const = {
+        .name = "usb_8dev",
+        .tseg1_min = 1,
+        .tseg1_max = 16,
+        .tseg2_min = 1,
+        .tseg2_max = 8,
+        .sjw_max = 4,
+        .brp_min = 1,
+        .brp_max = 1024,
+        .brp_inc = 1,
+};
+
+/* Probe USB device
+ *
+ * Check device and firmware.
+ * Set supported modes and bittiming constants.
+ * Allocate some memory.
+ */
+static int usb_8dev_probe(struct usb_interface *intf,
+                         const struct usb_device_id *id)
+{
+        struct net_device *netdev;
+        struct usb_8dev_priv *priv;
+        int i, err = -ENOMEM;
+        u32 version;
+        char buf[18];
+        struct usb_device *usbdev = interface_to_usbdev(intf);
+
+        /* product id looks strange, better we also check iProduct string */
+        if (usb_string(usbdev, usbdev->descriptor.iProduct, buf,
+                       sizeof(buf)) > 0 && strcmp(buf, "USB2CAN converter")) {
+                dev_info(&usbdev->dev, "ignoring: not an USB2CAN converter\n");
+                return -ENODEV;
+        }
+
+        netdev = alloc_candev(sizeof(struct usb_8dev_priv), MAX_TX_URBS);
+        if (!netdev) {
+                dev_err(&intf->dev, "Couldn't alloc candev\n");
+                return -ENOMEM;
+        }
+
+        priv = netdev_priv(netdev);
+
+        priv->udev = usbdev;
+        priv->netdev = netdev;
+
+        priv->can.state = CAN_STATE_STOPPED;
+        priv->can.clock.freq = USB_8DEV_ABP_CLOCK;
+        priv->can.bittiming_const = &usb_8dev_bittiming_const;
+        priv->can.do_set_mode = usb_8dev_set_mode;
+        priv->can.do_get_berr_counter = usb_8dev_get_berr_counter;
+        priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
+                                      CAN_CTRLMODE_LISTENONLY |
+                                      CAN_CTRLMODE_ONE_SHOT;
+
+        netdev->netdev_ops = &usb_8dev_netdev_ops;
+
+        netdev->flags |= IFF_ECHO; /* we support local echo */
+
+        init_usb_anchor(&priv->rx_submitted);
+
+        init_usb_anchor(&priv->tx_submitted);
+        atomic_set(&priv->active_tx_urbs, 0);
+
+        for (i = 0; i < MAX_TX_URBS; i++)
+                priv->tx_contexts[i].echo_index = MAX_TX_URBS;
+
+        priv->cmd_msg_buffer = kzalloc(sizeof(struct usb_8dev_cmd_msg),
+                                      GFP_KERNEL);
+        if (!priv->cmd_msg_buffer) {
+                netdev_err(netdev, "Couldn't alloc Tx buffer\n");
+                goto cleanup_candev;
+        }
+
+        usb_set_intfdata(intf, priv);
+
+        SET_NETDEV_DEV(netdev, &intf->dev);
+
+        mutex_init(&priv->usb_8dev_cmd_lock);
+
+        err = register_candev(netdev);
+        if (err) {
+                netdev_err(netdev,
+                        "couldn't register CAN device: %d\n", err);
+                goto cleanup_cmd_msg_buffer;
+        }
+
+        err = usb_8dev_cmd_version(priv, &version);
+        if (err) {
+                netdev_err(netdev, "can't get firmware version\n");
+                goto cleanup_cmd_msg_buffer;
+        } else {
+                netdev_info(netdev,
+                         "firmware: %d.%d, hardware: %d.%d\n",
+                         (version>>24) & 0xff, (version>>16) & 0xff,
+                         (version>>8) & 0xff, version & 0xff);
+        }
+
+        return 0;
+
+cleanup_cmd_msg_buffer:
+        kfree(priv->cmd_msg_buffer);
+
+cleanup_candev:
+        free_candev(netdev);
+
+        return err;
+
+}
+
+/* Called by the usb core when driver is unloaded or device is removed */
+static void usb_8dev_disconnect(struct usb_interface *intf)
+{
+        struct usb_8dev_priv *priv = usb_get_intfdata(intf);
+
+        usb_set_intfdata(intf, NULL);
+
+        if (priv) {
+                netdev_info(priv->netdev, "device disconnected\n");
+
+                unregister_netdev(priv->netdev);
+                free_candev(priv->netdev);
+
+                unlink_all_urbs(priv);
+        }
+
+}
+
+static struct usb_driver usb_8dev_driver = {
+        .name =         "usb_8dev",
+        .probe =        usb_8dev_probe,
+        .disconnect =   usb_8dev_disconnect,
+        .id_table =     usb_8dev_table,
+};
+
+module_usb_driver(usb_8dev_driver);
+
+MODULE_AUTHOR("Bernd Krumboeck <krumboeck@universalnet.at>");
+MODULE_DESCRIPTION("CAN driver for 8 devices USB2CAN interfaces");
+MODULE_LICENSE("GPL v2");