On 12/11/2012 06:57 PM, Bernd Krumboeck wrote:
> Add device driver for USB2CAN interface from "8 devices" 
> (http://www.8devices.com).
> 
> 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
> 
> Signed-off-by: Bernd Krumboeck <krumbo...@universalnet.at>

Looks quite good, some nitpicks inline.

Marc

> ---
>  drivers/net/can/usb/Kconfig    |    6 +
>  drivers/net/can/usb/Makefile   |    1 +
>  drivers/net/can/usb/usb_8dev.c | 1096 
> ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 1103 insertions(+)
>  create mode 100644 drivers/net/can/usb/usb_8dev.c
> 
> diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
> index a4e4bee..2162233 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 80a2ee4..becef46 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 0000000..2b0d848
> --- /dev/null
> +++ b/drivers/net/can/usb/usb_8dev.c
> @@ -0,0 +1,1096 @@
> +/*
> + * CAN driver for "8 devices" USB2CAN converter
> + *
> + * Copyright (C) 2012 Bernd Krumboeck (krumbo...@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 (i...@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                  10
> +#define MAX_TX_URBS                  10
> +#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
> +};
> +
> +/* bittiming constants */
> +#define USB_8DEV_ABP_CLOCK           32000000
> +#define USB_8DEV_BAUD_MANUAL         0x09
> +#define USB_8DEV_TSEG1_MIN           1
> +#define USB_8DEV_TSEG1_MAX           16
> +#define USB_8DEV_TSEG2_MIN           1
> +#define USB_8DEV_TSEG2_MAX           8
> +#define USB_8DEV_SJW_MAX             4
> +#define USB_8DEV_BRP_MIN             1
> +#define USB_8DEV_BRP_MAX             1024
> +#define USB_8DEV_BRP_INC             1
> +
> +/* 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
> +};
> +
> +#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               0x26  /* 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 flags = 0;
> +     u32 beflags;
> +     u16 bebrp;
> +     u32 ctrlmode = priv->can.ctrlmode;
> +

drop the "= 0" from the flags and move this:
        flags = USB_8DEV_STATUS_FRAME;

here

> +     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;
> +
> +     flags |= USB_8DEV_STATUS_FRAME;

and move the flags block down, just before copying the flags to the outmsg.

> +
> +     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 */
> +     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
> +             };

Please move the } one tab to the left.

> +
> +     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
> +             };

Please move the } one tab to the left.

> +
> +     int err = usb_8dev_send_cmd(priv, &outmsg, &inmsg);
> +     if (err)
> +             return err;
> +
> +     *res = be32_to_cpup((u32 *)inmsg.data);

__be32 instead of u32

> +
> +     return err;
> +}
> +
> +/* Get firmware version */
> +static ssize_t show_firmware(struct device *d, struct device_attribute *attr,
> +                          char *buf)
> +{
> +     struct usb_interface *intf = to_usb_interface(d);
> +     struct usb_8dev_priv *priv = usb_get_intfdata(intf);
> +     u16 result;
> +     struct usb_8dev_cmd_msg inmsg;
> +     struct usb_8dev_cmd_msg outmsg = {
> +             .channel = 0,
> +             .command = USB_8DEV_GET_SOFTW_VER,
> +             .opt1 = 0,
> +             .opt2 = 0
> +             };

Please move the } one tab to the left.

> +
> +     int err = usb_8dev_send_cmd(priv, &outmsg, &inmsg);
> +     if (err)
> +             return -EIO;
> +
> +     result = be16_to_cpup((u16 *)inmsg.data);

__be16

> +
> +     return sprintf(buf, "%d.%d\n", (u8)(result>>8), (u8)result);
> +}
> +
> +/* Get hardware version */
> +static ssize_t show_hardware(struct device *d, struct device_attribute *attr,
> +                          char *buf)
> +{
> +     struct usb_interface *intf = to_usb_interface(d);
> +     struct usb_8dev_priv *priv = usb_get_intfdata(intf);
> +     u16 result;
> +     struct usb_8dev_cmd_msg inmsg;
> +     struct usb_8dev_cmd_msg outmsg = {
> +             .channel = 0,
> +             .command = USB_8DEV_GET_HARDW_VER,
> +             .opt1 = 0,
> +             .opt2 = 0
> +             };

Please move the } one tab to the left.

> +
> +     int err = usb_8dev_send_cmd(priv, &outmsg, &inmsg);
> +     if (err)
> +             return -EIO;
> +
> +     result = be16_to_cpup((u16 *)inmsg.data);

__be16

> +
> +     return sprintf(buf, "%d.%d\n", (u8)(result>>8), (u8)result);
> +}
> +
> +static DEVICE_ATTR(firmware, S_IRUGO, show_firmware, NULL);
> +static DEVICE_ATTR(hardware, S_IRUGO, show_hardware, NULL);
> +
> +/*
> + * 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_ACK:
> +             cf->can_id |= CAN_ERR_ACK;
> +             tx_errors = 1;
> +             break;
> +     case USB_8DEV_STATUSMSG_CRC:
> +             cf->data[2] |= CAN_ERR_PROT_BIT;
> +             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_WARNING;
> +             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_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 if (msg->type == USB_8DEV_TYPE_ERROR_FRAME &&
> +                msg->flags == USB_8DEV_ERR_FLAG) {
> +             usb_8dev_rx_err_msg(priv, msg);
> +     } else {
> +             netdev_warn(priv->netdev, "frame type %d unknown",
> +                      msg->type);
> +     }
> +
> +}

The rx_can_msg function looks really nice now. It would look even
better, if you handle the errors first, then handle the normal packet, e.g.:
{

        if (msg->type == USB_8DEV_TYPE_ERROR_FRAME &&
                msg->flags == USB_8DEV_ERR_FLAG) {
                usb_8dev_rx_err_msg(priv, msg);
                return;
        } else if (msg->type != USB_8DEV_TYPE_CAN_FRAME) {
                netdev_warn(priv->netdev, "frame type %d unknown",
                        msg->type);
                return;
        }

        /* do rx here */

}

> +
> +/*
> + * 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 = USB_8DEV_TSEG1_MIN,
> +     .tseg1_max = USB_8DEV_TSEG1_MAX,
> +     .tseg2_min = USB_8DEV_TSEG2_MIN,
> +     .tseg2_max = USB_8DEV_TSEG2_MAX,
> +     .sjw_max = USB_8DEV_SJW_MAX,
> +     .brp_min = USB_8DEV_BRP_MIN,
> +     .brp_max = USB_8DEV_BRP_MAX,
> +     .brp_inc = USB_8DEV_BRP_INC,
> +};
> +
> +/*
> + * 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);
> +     }
> +
> +     if (device_create_file(&intf->dev, &dev_attr_firmware))
> +             netdev_err(netdev,
> +                     "Couldn't create device file for firmware\n");
> +
> +     if (device_create_file(&intf->dev, &dev_attr_hardware))
> +             netdev_err(netdev,
> +                     "Couldn't create device file for hardware\n");
> +
> +     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);
> +
> +     device_remove_file(&intf->dev, &dev_attr_firmware);
> +     device_remove_file(&intf->dev, &dev_attr_hardware);
> +
> +     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 <krumbo...@universalnet.at>");
> +MODULE_DESCRIPTION("CAN driver for 8 devices USB2CAN interfaces");
> +MODULE_LICENSE("GPL v2");
> 


-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |

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