// SPDX-License-Identifier: GPL-2.0-only
/*
 * CAN driver for esd electronics gmbh CAN-USB/2, CAN-USB/3 and CAN-USB/Micro
 *
 * Copyright (C) 2010-2012 esd electronic system design gmbh, Matthias Fuchs <socketcan@esd.eu>
 * Copyright (C) 2022-2024 esd electronics gmbh, Frank Jungclaus <frank.jungclaus@esd.eu>
 */

#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/error.h>
#include <linux/err.h>
#include <linux/ethtool.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/units.h>
#include <linux/usb.h>

MODULE_AUTHOR("Matthias Fuchs <socketcan@esd.eu>");
MODULE_AUTHOR("Frank Jungclaus <frank.jungclaus@esd.eu>");
MODULE_DESCRIPTION("CAN driver for esd electronics gmbh CAN-USB/2, CAN-USB/3 and CAN-USB/Micro interfaces");
MODULE_LICENSE("GPL v2");

/* USB vendor and product ID */
#define ESD_USB_ESDGMBH_VENDOR_ID       0x0ab4
#define ESD_USB_CANUSB2_PRODUCT_ID      0x0010
#define ESD_USB_CANUSBM_PRODUCT_ID      0x0011
#define ESD_USB_CANUSB3_PRODUCT_ID      0x0014

/* CAN controller clock frequencies */
#define ESD_USB_2_CAN_CLOCK     (60 * MEGA) /* Hz */
#define ESD_USB_M_CAN_CLOCK     (36 * MEGA) /* Hz */
#define ESD_USB_3_CAN_CLOCK     (80 * MEGA) /* Hz */

/* Maximum number of CAN nets */
#define ESD_USB_MAX_NETS        2

/* USB commands */
#define ESD_USB_CMD_VERSION             1 /* also used for VERSION_REPLY */
#define ESD_USB_CMD_CAN_RX              2 /* device to host only */
#define ESD_USB_CMD_CAN_TX              3 /* also used for TX_DONE */
#define ESD_USB_CMD_SETBAUD             4 /* also used for SETBAUD_REPLY */
#define ESD_USB_CMD_TS                  5 /* also used for TS_REPLY */
#define ESD_USB_CMD_IDADD               6 /* also used for IDADD_REPLY */

/* esd CAN message flags - dlc field */
#define ESD_USB_RTR     BIT(4)
#define ESD_USB_NO_BRS  BIT(4)
#define ESD_USB_ESI     BIT(5)
#define ESD_USB_FD      BIT(7)

/* esd CAN message flags - id field */
#define ESD_USB_EXTID   BIT(29)
#define ESD_USB_EVENT   BIT(30)
#define ESD_USB_IDMASK  GENMASK(28, 0)

/* esd CAN event ids */
#define ESD_USB_EV_CAN_ERROR_EXT        2 /* CAN controller specific diagnostic data */

/* baudrate message flags */
#define ESD_USB_LOM     BIT(30) /* Listen Only Mode */
#define ESD_USB_UBR     BIT(31) /* User Bit Rate (controller BTR) in bits 0..27 */
#define ESD_USB_NO_BAUDRATE     GENMASK(30, 0) /* bit rate unconfigured */

/* bit timing esd CAN-USB */
#define ESD_USB_2_TSEG1_SHIFT   16
#define ESD_USB_2_TSEG2_SHIFT   20
#define ESD_USB_2_SJW_SHIFT     14
#define ESD_USB_M_SJW_SHIFT     24
#define ESD_USB_TRIPLE_SAMPLES  BIT(23)

/* Transmitter Delay Compensation */
#define ESD_USB_3_TDC_MODE_AUTO 0

/* esd IDADD message */
#define ESD_USB_ID_ENABLE       BIT(7)
#define ESD_USB_MAX_ID_SEGMENT  64

/* SJA1000 ECC register (emulated by usb firmware) */
#define ESD_USB_SJA1000_ECC_SEG         GENMASK(4, 0)
#define ESD_USB_SJA1000_ECC_DIR         BIT(5)
#define ESD_USB_SJA1000_ECC_ERR         BIT(2, 1)
#define ESD_USB_SJA1000_ECC_BIT         0x00
#define ESD_USB_SJA1000_ECC_FORM        BIT(6)
#define ESD_USB_SJA1000_ECC_STUFF       BIT(7)
#define ESD_USB_SJA1000_ECC_MASK        GENMASK(7, 6)

/* esd bus state event codes */
#define ESD_USB_BUSSTATE_MASK   GENMASK(7, 6)
#define ESD_USB_BUSSTATE_WARN   BIT(6)
#define ESD_USB_BUSSTATE_ERRPASSIVE     BIT(7)
#define ESD_USB_BUSSTATE_BUSOFF GENMASK(7, 6)

#define ESD_USB_RX_BUFFER_SIZE          1024
#define ESD_USB_MAX_RX_URBS             4
#define ESD_USB_MAX_TX_URBS             16 /* must be power of 2 */

/* Modes for CAN-USB/3, to be used for esd_usb_3_set_baudrate_msg_x.mode */
#define ESD_USB_3_BAUDRATE_MODE_DISABLE         0 /* remove from bus */
#define ESD_USB_3_BAUDRATE_MODE_INDEX           1 /* ESD (CiA) bit rate idx */
#define ESD_USB_3_BAUDRATE_MODE_BTR_CTRL        2 /* BTR values (controller)*/
#define ESD_USB_3_BAUDRATE_MODE_BTR_CANONICAL   3 /* BTR values (canonical) */
#define ESD_USB_3_BAUDRATE_MODE_NUM             4 /* numerical bit rate */
#define ESD_USB_3_BAUDRATE_MODE_AUTOBAUD        5 /* autobaud */

/* Flags for CAN-USB/3, to be used for esd_usb_3_set_baudrate_msg_x.flags */
#define ESD_USB_3_BAUDRATE_FLAG_FD      BIT(0) /* enable CAN FD mode */
#define ESD_USB_3_BAUDRATE_FLAG_LOM     BIT(1) /* enable listen only mode */
#define ESD_USB_3_BAUDRATE_FLAG_STM     BIT(2) /* enable self test mode */
#define ESD_USB_3_BAUDRATE_FLAG_TRS     BIT(3) /* enable triple sampling */
#define ESD_USB_3_BAUDRATE_FLAG_TXP     BIT(4) /* enable transmit pause */

struct esd_usb_header_msg {
        u8 len; /* total message length in 32bit words */
        u8 cmd;
        u8 rsvd[2];
};

struct esd_usb_version_msg {
        u8 len; /* total message length in 32bit words */
        u8 cmd;
        u8 rsvd;
        u8 flags;
        __le32 drv_version;
};

struct esd_usb_version_reply_msg {
        u8 len; /* total message length in 32bit words */
        u8 cmd;
        u8 nets;
        u8 features;
        __le32 version;
        u8 name[16];
        __le32 rsvd;
        __le32 ts;
};

struct esd_usb_rx_msg {
        u8 len; /* total message length in 32bit words */
        u8 cmd;
        u8 net;
        u8 dlc;
        __le32 ts;
        __le32 id; /* upper 3 bits contain flags */
        union {
                u8 data[CAN_MAX_DLEN];
                u8 data_fd[CANFD_MAX_DLEN];
                struct {
                        u8 status; /* CAN Controller Status */
                        u8 ecc;    /* Error Capture Register */
                        u8 rec;    /* RX Error Counter */
                        u8 tec;    /* TX Error Counter */
                } ev_can_err_ext;  /* For ESD_EV_CAN_ERROR_EXT */
        };
};

struct esd_usb_tx_msg {
        u8 len; /* total message length in 32bit words */
        u8 cmd;
        u8 net;
        u8 dlc;
        u32 hnd;        /* opaque handle, not used by device */
        __le32 id; /* upper 3 bits contain flags */
        union {
                u8 data[CAN_MAX_DLEN];
                u8 data_fd[CANFD_MAX_DLEN];
        };
};

struct esd_usb_tx_done_msg {
        u8 len; /* total message length in 32bit words */
        u8 cmd;
        u8 net;
        u8 status;
        u32 hnd;        /* opaque handle, not used by device */
        __le32 ts;
};

struct esd_usb_id_filter_msg {
        u8 len; /* total message length in 32bit words */
        u8 cmd;
        u8 net;
        u8 option;
        __le32 mask[ESD_USB_MAX_ID_SEGMENT + 1]; /* +1 for 29bit extended IDs */
};

struct esd_usb_set_baudrate_msg {
        u8 len; /* total message length in 32bit words */
        u8 cmd;
        u8 net;
        u8 rsvd;
        __le32 baud;
};

/* CAN-USB/3 baudrate configuration, used for nominal as well as for data bit rate */
struct esd_usb_3_baudrate_cfg {
        __le16 brp;     /* bit rate pre-scaler */
        __le16 tseg1;   /* time segment before sample point */
        __le16 tseg2;   /* time segment after sample point */
        __le16 sjw;     /* synchronization jump Width */
};

/* In principle, the esd CAN-USB/3 supports Transmitter Delay Compensation (TDC),
 * but currently only the automatic TDC mode is supported by this driver.
 * An implementation for manual TDC configuration will follow.
 *
 * For information about struct esd_usb_3_tdc_cfg, see
 * NTCAN Application Developers Manual, 6.2.25 NTCAN_TDC_CFG + related chapters
 * https://esd.eu/fileadmin/esd/docs/manuals/NTCAN_Part1_Function_API_Manual_en_56.pdf
 */
struct esd_usb_3_tdc_cfg {
        u8 tdc_mode;    /* transmitter delay compensation mode  */
        u8 ssp_offset;  /* secondary sample point offset in mtq */
        s8 ssp_shift;   /* secondary sample point shift in mtq */
        u8 tdc_filter;  /* TDC filter in mtq */
};

/* Extended version of the above set_baudrate_msg for a CAN-USB/3
 * to define the CAN bit timing configuration of the CAN controller in
 * CAN FD mode as well as in Classical CAN mode.
 *
 * The payload of this command is a NTCAN_BAUDRATE_X structure according to
 * esd electronics gmbh, NTCAN Application Developers Manual, 6.2.15 NTCAN_BAUDRATE_X
 * https://esd.eu/fileadmin/esd/docs/manuals/NTCAN_Part1_Function_API_Manual_en_56.pdf
 */
struct esd_usb_3_set_baudrate_msg_x {
        u8 len; /* total message length in 32bit words */
        u8 cmd;
        u8 net;
        u8 rsvd;        /*reserved */
        /* Payload ... */
        __le16 mode;    /* mode word, see ESD_USB_3_BAUDRATE_MODE_xxx */
        __le16 flags;   /* control flags, see ESD_USB_3_BAUDRATE_FLAG_xxx */
        struct esd_usb_3_tdc_cfg tdc;   /* TDC configuration */
        struct esd_usb_3_baudrate_cfg nom;      /* nominal bit rate */
        struct esd_usb_3_baudrate_cfg data;     /* data bit rate */
};

/* Main message type used between library and application */
union __packed esd_usb_msg {
        struct esd_usb_header_msg hdr;
        struct esd_usb_version_msg version;
        struct esd_usb_version_reply_msg version_reply;
        struct esd_usb_rx_msg rx;
        struct esd_usb_tx_msg tx;
        struct esd_usb_tx_done_msg txdone;
        struct esd_usb_set_baudrate_msg setbaud;
        struct esd_usb_3_set_baudrate_msg_x setbaud_x;
        struct esd_usb_id_filter_msg filter;
};

static struct usb_device_id esd_usb_table[] = {
        {USB_DEVICE(ESD_USB_ESDGMBH_VENDOR_ID, ESD_USB_CANUSB2_PRODUCT_ID)},
        {USB_DEVICE(ESD_USB_ESDGMBH_VENDOR_ID, ESD_USB_CANUSBM_PRODUCT_ID)},
        {USB_DEVICE(ESD_USB_ESDGMBH_VENDOR_ID, ESD_USB_CANUSB3_PRODUCT_ID)},
        {}
};
MODULE_DEVICE_TABLE(usb, esd_usb_table);

struct esd_usb_net_priv;

struct esd_tx_urb_context {
        struct esd_usb_net_priv *priv;
        u32 echo_index;
};

struct esd_usb {
        struct usb_device *udev;
        struct esd_usb_net_priv *nets[ESD_USB_MAX_NETS];

        struct usb_anchor rx_submitted;

        unsigned int rx_pipe;
        unsigned int tx_pipe;

        int net_count;
        u32 version;
        int rxinitdone;
        int in_usb_disconnect;
        void *rxbuf[ESD_USB_MAX_RX_URBS];
        dma_addr_t rxbuf_dma[ESD_USB_MAX_RX_URBS];
};

struct esd_usb_net_priv {
        struct can_priv can; /* must be the first member */

        atomic_t active_tx_jobs;
        struct usb_anchor tx_submitted;
        struct esd_tx_urb_context tx_contexts[ESD_USB_MAX_TX_URBS];

        struct esd_usb *usb;
        struct net_device *netdev;
        int index;
        u8 old_state;
        struct can_berr_counter bec;
};

static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
                             union esd_usb_msg *msg)
{
        struct net_device_stats *stats = &priv->netdev->stats;
        struct can_frame *cf;
        struct sk_buff *skb;
        u32 id = le32_to_cpu(msg->rx.id) & ESD_USB_IDMASK;

        if (id == ESD_USB_EV_CAN_ERROR_EXT) {
                u8 state = msg->rx.ev_can_err_ext.status;
                u8 ecc = msg->rx.ev_can_err_ext.ecc;

                priv->bec.rxerr = msg->rx.ev_can_err_ext.rec;
                priv->bec.txerr = msg->rx.ev_can_err_ext.tec;

                netdev_dbg(priv->netdev,
                           "CAN_ERR_EV_EXT: dlc=%#02x state=%02x ecc=%02x rec=%02x tec=%02x\n",
                           msg->rx.dlc, state, ecc,
                           priv->bec.rxerr, priv->bec.txerr);

                /* if berr-reporting is off, only pass through on state change ... */
                if (!(priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING) &&
                    state == priv->old_state)
                        return;

                skb = alloc_can_err_skb(priv->netdev, &cf);
                if (!skb)
                        stats->rx_dropped++;

                if (state != priv->old_state) {
                        enum can_state tx_state, rx_state;
                        enum can_state new_state = CAN_STATE_ERROR_ACTIVE;

                        priv->old_state = state;

                        switch (state & ESD_USB_BUSSTATE_MASK) {
                        case ESD_USB_BUSSTATE_BUSOFF:
                                new_state = CAN_STATE_BUS_OFF;
                                can_bus_off(priv->netdev);
                                break;
                        case ESD_USB_BUSSTATE_WARN:
                                new_state = CAN_STATE_ERROR_WARNING;
                                break;
                        case ESD_USB_BUSSTATE_ERRPASSIVE:
                                new_state = CAN_STATE_ERROR_PASSIVE;
                                break;
                        default:
                                new_state = CAN_STATE_ERROR_ACTIVE;
                                priv->bec.txerr = 0;
                                priv->bec.rxerr = 0;
                                break;
                        }

                        if (new_state != priv->can.state) {
                                tx_state = (priv->bec.txerr >= priv->bec.rxerr) ? new_state : 0;
                                rx_state = (priv->bec.txerr <= priv->bec.rxerr) ? new_state : 0;
                                can_change_state(priv->netdev, cf,
                                                 tx_state, rx_state);
                        }
                } else if (skb) {
                        priv->can.can_stats.bus_error++;
                        stats->rx_errors++;

                        cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;

                        switch (ecc & ESD_USB_SJA1000_ECC_MASK) {
                        case ESD_USB_SJA1000_ECC_BIT:
                                cf->data[2] |= CAN_ERR_PROT_BIT;
                                break;
                        case ESD_USB_SJA1000_ECC_FORM:
                                cf->data[2] |= CAN_ERR_PROT_FORM;
                                break;
                        case ESD_USB_SJA1000_ECC_STUFF:
                                cf->data[2] |= CAN_ERR_PROT_STUFF;
                                break;
                        default:
                                break;
                        }

                        /* Error occurred during transmission? */
                        if (!(ecc & ESD_USB_SJA1000_ECC_DIR))
                                cf->data[2] |= CAN_ERR_PROT_TX;

                        /* Bit stream position in CAN frame as the error was detected */
                        cf->data[3] = ecc & ESD_USB_SJA1000_ECC_SEG;
                }

                if (skb) {
                        cf->can_id |= CAN_ERR_CNT;
                        cf->data[6] = priv->bec.txerr;
                        cf->data[7] = priv->bec.rxerr;

                        netif_rx(skb);
                }
        }
}

static void esd_usb_rx_can_msg(struct esd_usb_net_priv *priv,
                               union esd_usb_msg *msg)
{
        struct net_device_stats *stats = &priv->netdev->stats;
        struct can_frame *cf;
        struct canfd_frame *cfd;
        struct sk_buff *skb;
        u32 id;
        u8 len;

        if (!netif_device_present(priv->netdev))
                return;

        id = le32_to_cpu(msg->rx.id);

        if (id & ESD_USB_EVENT) {
                esd_usb_rx_event(priv, msg);
        } else {
                if (msg->rx.dlc & ESD_USB_FD) {
                        skb = alloc_canfd_skb(priv->netdev, &cfd);
                } else {
                        skb = alloc_can_skb(priv->netdev, &cf);
                        cfd = (struct canfd_frame *)cf;
                }

                if (skb == NULL) {
                        stats->rx_dropped++;
                        return;
                }

                cfd->can_id = id & ESD_USB_IDMASK;

                if (msg->rx.dlc & ESD_USB_FD) {
                        /* masking by 0x0F is already done within can_fd_dlc2len() */
                        cfd->len = can_fd_dlc2len(msg->rx.dlc);
                        len = cfd->len;
                        if ((msg->rx.dlc & ESD_USB_NO_BRS) == 0)
                                cfd->flags |= CANFD_BRS;
                        if (msg->rx.dlc & ESD_USB_ESI)
                                cfd->flags |= CANFD_ESI;
                } else {
                        can_frame_set_cc_len(cf, msg->rx.dlc & ~ESD_USB_RTR, priv->can.ctrlmode);
                        len = cf->len;
                        if (msg->rx.dlc & ESD_USB_RTR) {
                                cf->can_id |= CAN_RTR_FLAG;
                                len = 0;
                        }
                }

                if (id & ESD_USB_EXTID)
                        cfd->can_id |= CAN_EFF_FLAG;

                memcpy(cfd->data, msg->rx.data_fd, len);
                stats->rx_bytes += len;
                stats->rx_packets++;

                netif_rx(skb);
        }
}

static void esd_usb_tx_done_msg(struct esd_usb_net_priv *priv,
                                union esd_usb_msg *msg)
{
        struct net_device_stats *stats = &priv->netdev->stats;
        struct net_device *netdev = priv->netdev;
        struct esd_tx_urb_context *context;

        if (!netif_device_present(netdev))
                return;

        context = &priv->tx_contexts[msg->txdone.hnd & (ESD_USB_MAX_TX_URBS - 1)];

        if (!msg->txdone.status) {
                stats->tx_packets++;
                stats->tx_bytes += can_get_echo_skb(netdev, context->echo_index,
                                                    NULL);
        } else {
                stats->tx_errors++;
                can_free_echo_skb(netdev, context->echo_index, NULL);
        }

        /* Release context */
        context->echo_index = ESD_USB_MAX_TX_URBS;
        atomic_dec(&priv->active_tx_jobs);

        netif_wake_queue(netdev);
}

static void esd_usb_read_bulk_callback(struct urb *urb)
{
        struct esd_usb *dev = urb->context;
        int err;
        int pos = 0;
        int i;

        switch (urb->status) {
        case 0: /* success */
                break;

        case -ENOENT:
        case -EPIPE:
        case -EPROTO:
        case -ESHUTDOWN:
                return;

        default:
                dev_info(dev->udev->dev.parent,
                         "Rx URB aborted (%pe)\n", ERR_PTR(urb->status));
                goto resubmit_urb;
        }

        while (pos < urb->actual_length) {
                union esd_usb_msg *msg;

                msg = (union esd_usb_msg *)(urb->transfer_buffer + pos);

                switch (msg->hdr.cmd) {
                case ESD_USB_CMD_CAN_RX:
                        if (msg->rx.net >= dev->net_count) {
                                dev_err(dev->udev->dev.parent, "format error\n");
                                break;
                        }

                        esd_usb_rx_can_msg(dev->nets[msg->rx.net], msg);
                        break;

                case ESD_USB_CMD_CAN_TX:
                        if (msg->txdone.net >= dev->net_count) {
                                dev_err(dev->udev->dev.parent, "format error\n");
                                break;
                        }

                        esd_usb_tx_done_msg(dev->nets[msg->txdone.net],
                                            msg);
                        break;
                }

                pos += msg->hdr.len * sizeof(u32); /* convert to # of bytes */

                if (pos > urb->actual_length) {
                        dev_err(dev->udev->dev.parent, "format error\n");
                        break;
                }
        }

resubmit_urb:
        usb_fill_bulk_urb(urb, dev->udev, dev->rx_pipe,
                          urb->transfer_buffer, ESD_USB_RX_BUFFER_SIZE,
                          esd_usb_read_bulk_callback, dev);

        usb_anchor_urb(urb, &dev->rx_submitted);

        err = usb_submit_urb(urb, GFP_ATOMIC);
        if (!err)
                return;

        usb_unanchor_urb(urb);

        if (err == -ENODEV) {
                for (i = 0; i < dev->net_count; i++) {
                        if (dev->nets[i])
                                netif_device_detach(dev->nets[i]->netdev);
                }
        } else {
                dev_err(dev->udev->dev.parent,
                        "failed resubmitting read bulk urb: %pe\n", ERR_PTR(err));
        }
}

/* callback for bulk IN urb */
static void esd_usb_write_bulk_callback(struct urb *urb)
{
        struct esd_tx_urb_context *context = urb->context;
        struct esd_usb_net_priv *priv;
        struct net_device *netdev;
        size_t size = sizeof(union esd_usb_msg);

        WARN_ON(!context);

        priv = context->priv;
        netdev = priv->netdev;

        /* free up our allocated buffer */
        usb_free_coherent(urb->dev, size,
                          urb->transfer_buffer, urb->transfer_dma);

        if (!netif_device_present(netdev))
                return;

        if (urb->status)
                netdev_info(netdev, "Tx URB aborted (%pe)\n", ERR_PTR(urb->status));

        netif_trans_update(netdev);
}

static ssize_t firmware_show(struct device *d,
                             struct device_attribute *attr, char *buf)
{
        struct usb_interface *intf = to_usb_interface(d);
        struct esd_usb *dev = usb_get_intfdata(intf);

        return sprintf(buf, "%d.%d.%d\n",
                       (dev->version >> 12) & 0xf,
                       (dev->version >> 8) & 0xf,
                       dev->version & 0xff);
}
static DEVICE_ATTR_RO(firmware);

static ssize_t hardware_show(struct device *d,
                             struct device_attribute *attr, char *buf)
{
        struct usb_interface *intf = to_usb_interface(d);
        struct esd_usb *dev = usb_get_intfdata(intf);

        return sprintf(buf, "%d.%d.%d\n",
                       (dev->version >> 28) & 0xf,
                       (dev->version >> 24) & 0xf,
                       (dev->version >> 16) & 0xff);
}
static DEVICE_ATTR_RO(hardware);

static ssize_t nets_show(struct device *d,
                         struct device_attribute *attr, char *buf)
{
        struct usb_interface *intf = to_usb_interface(d);
        struct esd_usb *dev = usb_get_intfdata(intf);

        return sprintf(buf, "%d", dev->net_count);
}
static DEVICE_ATTR_RO(nets);

static int esd_usb_send_msg(struct esd_usb *dev, union esd_usb_msg *msg)
{
        int actual_length;

        return usb_bulk_msg(dev->udev, dev->tx_pipe, msg,
                            msg->hdr.len * sizeof(u32), /* convert to # of bytes */
                            &actual_length,
                            1000);
}

static int esd_usb_wait_msg(struct esd_usb *dev,
                            union esd_usb_msg *msg)
{
        int actual_length;

        return usb_bulk_msg(dev->udev, dev->rx_pipe, msg,
                            sizeof(*msg), &actual_length, 1000);
}

static int esd_usb_setup_rx_urbs(struct esd_usb *dev)
{
        int i, err = 0;

        if (dev->rxinitdone)
                return 0;

        for (i = 0; i < ESD_USB_MAX_RX_URBS; i++) {
                struct urb *urb = NULL;
                u8 *buf = NULL;
                dma_addr_t buf_dma;

                /* create a URB, and a buffer for it */
                urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!urb) {
                        err = -ENOMEM;
                        break;
                }

                buf = usb_alloc_coherent(dev->udev, ESD_USB_RX_BUFFER_SIZE, GFP_KERNEL,
                                         &buf_dma);
                if (!buf) {
                        dev_warn(dev->udev->dev.parent,
                                 "No memory left for USB buffer\n");
                        err = -ENOMEM;
                        goto freeurb;
                }

                urb->transfer_dma = buf_dma;

                usb_fill_bulk_urb(urb, dev->udev, dev->rx_pipe,
                                  buf, ESD_USB_RX_BUFFER_SIZE,
                                  esd_usb_read_bulk_callback, dev);
                urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
                usb_anchor_urb(urb, &dev->rx_submitted);

                err = usb_submit_urb(urb, GFP_KERNEL);
                if (err) {
                        usb_unanchor_urb(urb);
                        usb_free_coherent(dev->udev, ESD_USB_RX_BUFFER_SIZE, buf,
                                          urb->transfer_dma);
                        goto freeurb;
                }

                dev->rxbuf[i] = buf;
                dev->rxbuf_dma[i] = buf_dma;

freeurb:
                /* Drop reference, USB core will take care of freeing it */
                usb_free_urb(urb);
                if (err)
                        break;
        }

        /* Did we submit any URBs */
        if (i == 0) {
                dev_err(dev->udev->dev.parent, "couldn't setup read URBs\n");
                return err;
        }

        /* Warn if we've couldn't transmit all the URBs */
        if (i < ESD_USB_MAX_RX_URBS) {
                dev_warn(dev->udev->dev.parent,
                         "rx performance may be slow\n");
        }

        dev->rxinitdone = 1;
        return 0;
}

/* Start interface */
static int esd_usb_start(struct esd_usb_net_priv *priv)
{
        struct esd_usb *dev = priv->usb;
        struct net_device *netdev = priv->netdev;
        union esd_usb_msg *msg;
        int err, i;

        msg = kmalloc_obj(*msg);
        if (!msg) {
                err = -ENOMEM;
                goto out;
        }

        /* Enable all IDs
         * The IDADD message takes up to 64 32 bit bitmasks (2048 bits).
         * Each bit represents one 11 bit CAN identifier. A set bit
         * enables reception of the corresponding CAN identifier. A cleared
         * bit disabled this identifier. An additional bitmask value
         * following the CAN 2.0A bits is used to enable reception of
         * extended CAN frames. Only the LSB of this final mask is checked
         * for the complete 29 bit ID range. The IDADD message also allows
         * filter configuration for an ID subset. In this case you can add
         * the number of the starting bitmask (0..64) to the filter.option
         * field followed by only some bitmasks.
         */
        msg->hdr.cmd = ESD_USB_CMD_IDADD;
        msg->hdr.len = sizeof(struct esd_usb_id_filter_msg) / sizeof(u32); /* # of 32bit words */
        msg->filter.net = priv->index;
        msg->filter.option = ESD_USB_ID_ENABLE; /* start with segment 0 */
        for (i = 0; i < ESD_USB_MAX_ID_SEGMENT; i++)
                msg->filter.mask[i] = cpu_to_le32(GENMASK(31, 0));
        /* enable 29bit extended IDs */
        msg->filter.mask[ESD_USB_MAX_ID_SEGMENT] = cpu_to_le32(BIT(0));

        err = esd_usb_send_msg(dev, msg);
        if (err)
                goto out;

        err = esd_usb_setup_rx_urbs(dev);
        if (err)
                goto out;

        priv->can.state = CAN_STATE_ERROR_ACTIVE;

out:
        if (err == -ENODEV)
                netif_device_detach(netdev);
        if (err)
                netdev_err(netdev, "couldn't start device: %pe\n", ERR_PTR(err));

        kfree(msg);
        return err;
}

static void unlink_all_urbs(struct esd_usb *dev)
{
        struct esd_usb_net_priv *priv;
        int i, j;

        usb_kill_anchored_urbs(&dev->rx_submitted);

        for (i = 0; i < ESD_USB_MAX_RX_URBS; ++i)
                usb_free_coherent(dev->udev, ESD_USB_RX_BUFFER_SIZE,
                                  dev->rxbuf[i], dev->rxbuf_dma[i]);

        for (i = 0; i < dev->net_count; i++) {
                priv = dev->nets[i];
                if (priv) {
                        usb_kill_anchored_urbs(&priv->tx_submitted);
                        atomic_set(&priv->active_tx_jobs, 0);

                        for (j = 0; j < ESD_USB_MAX_TX_URBS; j++)
                                priv->tx_contexts[j].echo_index = ESD_USB_MAX_TX_URBS;
                }
        }
}

static int esd_usb_open(struct net_device *netdev)
{
        struct esd_usb_net_priv *priv = netdev_priv(netdev);
        int err;

        /* common open */
        err = open_candev(netdev);
        if (err)
                return err;

        /* finally start device */
        err = esd_usb_start(priv);
        if (err) {
                close_candev(netdev);
                return err;
        }

        netif_start_queue(netdev);

        return 0;
}

static netdev_tx_t esd_usb_start_xmit(struct sk_buff *skb,
                                      struct net_device *netdev)
{
        struct esd_usb_net_priv *priv = netdev_priv(netdev);
        struct esd_usb *dev = priv->usb;
        struct esd_tx_urb_context *context = NULL;
        struct net_device_stats *stats = &netdev->stats;
        struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
        union esd_usb_msg *msg;
        struct urb *urb;
        u8 *buf;
        int i, err;
        int ret = NETDEV_TX_OK;
        size_t size = sizeof(union esd_usb_msg);

        if (can_dev_dropped_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) {
                stats->tx_dropped++;
                dev_kfree_skb(skb);
                goto nourbmem;
        }

        buf = usb_alloc_coherent(dev->udev, size, GFP_ATOMIC,
                                 &urb->transfer_dma);
        if (!buf) {
                netdev_err(netdev, "No memory left for USB buffer\n");
                stats->tx_dropped++;
                dev_kfree_skb(skb);
                goto nobufmem;
        }

        msg = (union esd_usb_msg *)buf;

        /* minimal length as # of 32bit words */
        msg->hdr.len = offsetof(struct esd_usb_tx_msg, data) / sizeof(u32);
        msg->hdr.cmd = ESD_USB_CMD_CAN_TX;
        msg->tx.net = priv->index;

        if (can_is_canfd_skb(skb)) {
                msg->tx.dlc = can_fd_len2dlc(cfd->len);
                msg->tx.dlc |= ESD_USB_FD;

                if ((cfd->flags & CANFD_BRS) == 0)
                        msg->tx.dlc |= ESD_USB_NO_BRS;
        } else {
                msg->tx.dlc = can_get_cc_dlc((struct can_frame *)cfd, priv->can.ctrlmode);

                if (cfd->can_id & CAN_RTR_FLAG)
                        msg->tx.dlc |= ESD_USB_RTR;
        }

        msg->tx.id = cpu_to_le32(cfd->can_id & CAN_ERR_MASK);

        if (cfd->can_id & CAN_EFF_FLAG)
                msg->tx.id |= cpu_to_le32(ESD_USB_EXTID);

        memcpy(msg->tx.data_fd, cfd->data, cfd->len);

        /* round up, then divide by 4 to add the payload length as # of 32bit words */
        msg->hdr.len += DIV_ROUND_UP(cfd->len, sizeof(u32));

        for (i = 0; i < ESD_USB_MAX_TX_URBS; i++) {
                if (priv->tx_contexts[i].echo_index == ESD_USB_MAX_TX_URBS) {
                        context = &priv->tx_contexts[i];
                        break;
                }
        }

        /* This may never happen */
        if (!context) {
                netdev_warn(netdev, "couldn't find free context\n");
                ret = NETDEV_TX_BUSY;
                goto releasebuf;
        }

        context->priv = priv;
        context->echo_index = i;

        /* hnd must not be 0 - MSB is stripped in txdone handling */
        msg->tx.hnd = BIT(31) | i; /* returned in TX done message */

        usb_fill_bulk_urb(urb, dev->udev, dev->tx_pipe, buf,
                          msg->hdr.len * sizeof(u32), /* convert to # of bytes */
                          esd_usb_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, 0);

        atomic_inc(&priv->active_tx_jobs);

        /* Slow down tx path */
        if (atomic_read(&priv->active_tx_jobs) >= ESD_USB_MAX_TX_URBS)
                netif_stop_queue(netdev);

        err = usb_submit_urb(urb, GFP_ATOMIC);
        if (err) {
                can_free_echo_skb(netdev, context->echo_index, NULL);

                atomic_dec(&priv->active_tx_jobs);
                usb_unanchor_urb(urb);

                stats->tx_dropped++;

                if (err == -ENODEV)
                        netif_device_detach(netdev);
                else
                        netdev_warn(netdev, "failed tx_urb %pe\n", ERR_PTR(err));

                goto releasebuf;
        }

        netif_trans_update(netdev);

        /* Release our reference to this URB, the USB core will eventually free
         * it entirely.
         */
        usb_free_urb(urb);

        return NETDEV_TX_OK;

releasebuf:
        usb_free_coherent(dev->udev, size, buf, urb->transfer_dma);

nobufmem:
        usb_free_urb(urb);

nourbmem:
        return ret;
}

/* Stop interface */
static int esd_usb_stop(struct esd_usb_net_priv *priv)
{
        union esd_usb_msg *msg;
        int err;
        int i;

        msg = kmalloc_obj(*msg);
        if (!msg)
                return -ENOMEM;

        /* Disable all IDs (see esd_usb_start()) */
        msg->hdr.cmd = ESD_USB_CMD_IDADD;
        msg->hdr.len = sizeof(struct esd_usb_id_filter_msg) / sizeof(u32);/* # of 32bit words */
        msg->filter.net = priv->index;
        msg->filter.option = ESD_USB_ID_ENABLE; /* start with segment 0 */
        for (i = 0; i <= ESD_USB_MAX_ID_SEGMENT; i++)
                msg->filter.mask[i] = 0;
        err = esd_usb_send_msg(priv->usb, msg);
        if (err < 0) {
                netdev_err(priv->netdev, "sending idadd message failed: %pe\n", ERR_PTR(err));
                goto bail;
        }

        /* set CAN controller to reset mode */
        msg->hdr.len = sizeof(struct esd_usb_set_baudrate_msg) / sizeof(u32); /* # of 32bit words */
        msg->hdr.cmd = ESD_USB_CMD_SETBAUD;
        msg->setbaud.net = priv->index;
        msg->setbaud.rsvd = 0;
        msg->setbaud.baud = cpu_to_le32(ESD_USB_NO_BAUDRATE);
        err = esd_usb_send_msg(priv->usb, msg);
        if (err < 0)
                netdev_err(priv->netdev, "sending setbaud message failed: %pe\n", ERR_PTR(err));

bail:
        kfree(msg);

        return err;
}

static int esd_usb_close(struct net_device *netdev)
{
        struct esd_usb_net_priv *priv = netdev_priv(netdev);
        int err = 0;

        if (!priv->usb->in_usb_disconnect) {
                /* It's moot to try this in usb_disconnect()! */
                err = esd_usb_stop(priv);
        }

        priv->can.state = CAN_STATE_STOPPED;

        netif_stop_queue(netdev);

        close_candev(netdev);

        return err;
}

static const struct net_device_ops esd_usb_netdev_ops = {
        .ndo_open = esd_usb_open,
        .ndo_stop = esd_usb_close,
        .ndo_start_xmit = esd_usb_start_xmit,
};

static const struct ethtool_ops esd_usb_ethtool_ops = {
        .get_ts_info = ethtool_op_get_ts_info,
};

static const struct can_bittiming_const esd_usb_2_bittiming_const = {
        .name = "esd_usb_2",
        .tseg1_min = 1,
        .tseg1_max = 16,
        .tseg2_min = 1,
        .tseg2_max = 8,
        .sjw_max = 4,
        .brp_min = 1,
        .brp_max = 1024,
        .brp_inc = 1,
};

static int esd_usb_2_set_bittiming(struct net_device *netdev)
{
        const struct can_bittiming_const *btc = &esd_usb_2_bittiming_const;
        struct esd_usb_net_priv *priv = netdev_priv(netdev);
        struct can_bittiming *bt = &priv->can.bittiming;
        union esd_usb_msg *msg;
        int err;
        u32 canbtr;
        int sjw_shift;

        canbtr = ESD_USB_UBR;
        if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
                canbtr |= ESD_USB_LOM;

        canbtr |= (bt->brp - 1) & (btc->brp_max - 1);

        if (le16_to_cpu(priv->usb->udev->descriptor.idProduct) ==
            ESD_USB_CANUSBM_PRODUCT_ID)
                sjw_shift = ESD_USB_M_SJW_SHIFT;
        else
                sjw_shift = ESD_USB_2_SJW_SHIFT;

        canbtr |= ((bt->sjw - 1) & (btc->sjw_max - 1))
                << sjw_shift;
        canbtr |= ((bt->prop_seg + bt->phase_seg1 - 1)
                   & (btc->tseg1_max - 1))
                << ESD_USB_2_TSEG1_SHIFT;
        canbtr |= ((bt->phase_seg2 - 1) & (btc->tseg2_max - 1))
                << ESD_USB_2_TSEG2_SHIFT;
        if (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
                canbtr |= ESD_USB_TRIPLE_SAMPLES;

        msg = kmalloc_obj(*msg);
        if (!msg)
                return -ENOMEM;

        msg->hdr.len = sizeof(struct esd_usb_set_baudrate_msg) / sizeof(u32); /* # of 32bit words */
        msg->hdr.cmd = ESD_USB_CMD_SETBAUD;
        msg->setbaud.net = priv->index;
        msg->setbaud.rsvd = 0;
        msg->setbaud.baud = cpu_to_le32(canbtr);

        netdev_dbg(netdev, "setting BTR=%#x\n", canbtr);

        err = esd_usb_send_msg(priv->usb, msg);

        kfree(msg);
        return err;
}

/* Nominal bittiming constants, see
 * Microchip SAM E70/S70/V70/V71, Data Sheet, Rev. G - 07/2022
 * 48.6.8 MCAN Nominal Bit Timing and Prescaler Register
 */
static const struct can_bittiming_const esd_usb_3_nom_bittiming_const = {
        .name = "esd_usb_3",
        .tseg1_min = 2,
        .tseg1_max = 256,
        .tseg2_min = 2,
        .tseg2_max = 128,
        .sjw_max = 128,
        .brp_min = 1,
        .brp_max = 512,
        .brp_inc = 1,
};

/* Data bittiming constants, see
 * Microchip SAM E70/S70/V70/V71, Data Sheet, Rev. G - 07/2022
 * 48.6.4 MCAN Data Bit Timing and Prescaler Register
 */
static const struct can_bittiming_const esd_usb_3_data_bittiming_const = {
        .name = "esd_usb_3",
        .tseg1_min = 2,
        .tseg1_max = 32,
        .tseg2_min = 1,
        .tseg2_max = 16,
        .sjw_max = 8,
        .brp_min = 1,
        .brp_max = 32,
        .brp_inc = 1,
};

static int esd_usb_3_set_bittiming(struct net_device *netdev)
{
        const struct can_bittiming_const *nom_btc = &esd_usb_3_nom_bittiming_const;
        const struct can_bittiming_const *data_btc = &esd_usb_3_data_bittiming_const;
        struct esd_usb_net_priv *priv = netdev_priv(netdev);
        struct can_bittiming *nom_bt = &priv->can.bittiming;
        struct can_bittiming *data_bt = &priv->can.fd.data_bittiming;
        struct esd_usb_3_set_baudrate_msg_x *baud_x;
        union esd_usb_msg *msg;
        u16 flags = 0;
        int err;

        msg = kmalloc_obj(*msg);
        if (!msg)
                return -ENOMEM;

        baud_x = &msg->setbaud_x;

        /* Canonical is the most reasonable mode for SocketCAN on CAN-USB/3 ... */
        baud_x->mode = cpu_to_le16(ESD_USB_3_BAUDRATE_MODE_BTR_CANONICAL);

        if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
                flags |= ESD_USB_3_BAUDRATE_FLAG_LOM;

        baud_x->nom.brp = cpu_to_le16(nom_bt->brp & (nom_btc->brp_max - 1));
        baud_x->nom.sjw = cpu_to_le16(nom_bt->sjw & (nom_btc->sjw_max - 1));
        baud_x->nom.tseg1 = cpu_to_le16((nom_bt->prop_seg + nom_bt->phase_seg1)
                                        & (nom_btc->tseg1_max - 1));
        baud_x->nom.tseg2 = cpu_to_le16(nom_bt->phase_seg2 & (nom_btc->tseg2_max - 1));

        if (priv->can.ctrlmode & CAN_CTRLMODE_FD) {
                baud_x->data.brp = cpu_to_le16(data_bt->brp & (data_btc->brp_max - 1));
                baud_x->data.sjw = cpu_to_le16(data_bt->sjw & (data_btc->sjw_max - 1));
                baud_x->data.tseg1 = cpu_to_le16((data_bt->prop_seg + data_bt->phase_seg1)
                                                 & (data_btc->tseg1_max - 1));
                baud_x->data.tseg2 = cpu_to_le16(data_bt->phase_seg2 & (data_btc->tseg2_max - 1));
                flags |= ESD_USB_3_BAUDRATE_FLAG_FD;
        }

        /* Currently this driver only supports the automatic TDC mode */
        baud_x->tdc.tdc_mode = ESD_USB_3_TDC_MODE_AUTO;
        baud_x->tdc.ssp_offset = 0;
        baud_x->tdc.ssp_shift = 0;
        baud_x->tdc.tdc_filter = 0;

        baud_x->flags = cpu_to_le16(flags);
        baud_x->net = priv->index;
        baud_x->rsvd = 0;

        /* set len as # of 32bit words */
        msg->hdr.len = sizeof(struct esd_usb_3_set_baudrate_msg_x) / sizeof(u32);
        msg->hdr.cmd = ESD_USB_CMD_SETBAUD;

        netdev_dbg(netdev,
                   "ctrlmode=%#x/%#x, esd-net=%u, esd-mode=%#x, esd-flags=%#x\n",
                   priv->can.ctrlmode, priv->can.ctrlmode_supported,
                   priv->index, le16_to_cpu(baud_x->mode), flags);

        err = esd_usb_send_msg(priv->usb, msg);

        kfree(msg);
        return err;
}

static int esd_usb_get_berr_counter(const struct net_device *netdev,
                                    struct can_berr_counter *bec)
{
        struct esd_usb_net_priv *priv = netdev_priv(netdev);

        bec->txerr = priv->bec.txerr;
        bec->rxerr = priv->bec.rxerr;

        return 0;
}

static int esd_usb_set_mode(struct net_device *netdev, enum can_mode mode)
{
        switch (mode) {
        case CAN_MODE_START:
                netif_wake_queue(netdev);
                break;

        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int esd_usb_probe_one_net(struct usb_interface *intf, int index)
{
        struct esd_usb *dev = usb_get_intfdata(intf);
        struct net_device *netdev;
        struct esd_usb_net_priv *priv;
        int err = 0;
        int i;

        netdev = alloc_candev(sizeof(*priv), ESD_USB_MAX_TX_URBS);
        if (!netdev) {
                dev_err(&intf->dev, "couldn't alloc candev\n");
                err = -ENOMEM;
                goto done;
        }

        priv = netdev_priv(netdev);

        init_usb_anchor(&priv->tx_submitted);
        atomic_set(&priv->active_tx_jobs, 0);

        for (i = 0; i < ESD_USB_MAX_TX_URBS; i++)
                priv->tx_contexts[i].echo_index = ESD_USB_MAX_TX_URBS;

        priv->usb = dev;
        priv->netdev = netdev;
        priv->index = index;

        priv->can.state = CAN_STATE_STOPPED;
        priv->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY |
                CAN_CTRLMODE_CC_LEN8_DLC |
                CAN_CTRLMODE_BERR_REPORTING;

        switch (le16_to_cpu(dev->udev->descriptor.idProduct)) {
        case ESD_USB_CANUSB3_PRODUCT_ID:
                priv->can.clock.freq = ESD_USB_3_CAN_CLOCK;
                priv->can.ctrlmode_supported |= CAN_CTRLMODE_FD;
                priv->can.bittiming_const = &esd_usb_3_nom_bittiming_const;
                priv->can.fd.data_bittiming_const = &esd_usb_3_data_bittiming_const;
                priv->can.do_set_bittiming = esd_usb_3_set_bittiming;
                priv->can.fd.do_set_data_bittiming = esd_usb_3_set_bittiming;
                break;

        case ESD_USB_CANUSBM_PRODUCT_ID:
                priv->can.clock.freq = ESD_USB_M_CAN_CLOCK;
                priv->can.bittiming_const = &esd_usb_2_bittiming_const;
                priv->can.do_set_bittiming = esd_usb_2_set_bittiming;
                break;

        case ESD_USB_CANUSB2_PRODUCT_ID:
        default:
                priv->can.clock.freq = ESD_USB_2_CAN_CLOCK;
                priv->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
                priv->can.bittiming_const = &esd_usb_2_bittiming_const;
                priv->can.do_set_bittiming = esd_usb_2_set_bittiming;
                break;
        }

        priv->can.do_set_mode = esd_usb_set_mode;
        priv->can.do_get_berr_counter = esd_usb_get_berr_counter;

        netdev->flags |= IFF_ECHO; /* we support local echo */

        netdev->netdev_ops = &esd_usb_netdev_ops;
        netdev->ethtool_ops = &esd_usb_ethtool_ops;

        SET_NETDEV_DEV(netdev, &intf->dev);
        netdev->dev_id = index;

        err = register_candev(netdev);
        if (err) {
                dev_err(&intf->dev, "couldn't register CAN device: %pe\n", ERR_PTR(err));
                free_candev(netdev);
                err = -ENOMEM;
                goto done;
        }

        dev->nets[index] = priv;
        netdev_info(netdev, "registered\n");

done:
        return err;
}

/* probe function for new USB devices
 *
 * check version information and number of available
 * CAN interfaces
 */
static int esd_usb_probe(struct usb_interface *intf,
                         const struct usb_device_id *id)
{
        struct usb_endpoint_descriptor *ep_in, *ep_out;
        struct esd_usb *dev;
        union esd_usb_msg *msg;
        int i, err;

        err = usb_find_common_endpoints(intf->cur_altsetting, &ep_in, &ep_out,
                                        NULL, NULL);
        if (err)
                return err;

        dev = kzalloc_obj(*dev);
        if (!dev) {
                err = -ENOMEM;
                goto done;
        }

        dev->udev = interface_to_usbdev(intf);
        dev->rx_pipe = usb_rcvbulkpipe(dev->udev, ep_in->bEndpointAddress);
        dev->tx_pipe = usb_sndbulkpipe(dev->udev, ep_out->bEndpointAddress);

        init_usb_anchor(&dev->rx_submitted);

        usb_set_intfdata(intf, dev);

        msg = kmalloc_obj(*msg);
        if (!msg) {
                err = -ENOMEM;
                goto free_msg;
        }

        /* query number of CAN interfaces (nets) */
        msg->hdr.cmd = ESD_USB_CMD_VERSION;
        msg->hdr.len = sizeof(struct esd_usb_version_msg) / sizeof(u32); /* # of 32bit words */
        msg->version.rsvd = 0;
        msg->version.flags = 0;
        msg->version.drv_version = 0;

        err = esd_usb_send_msg(dev, msg);
        if (err < 0) {
                dev_err(&intf->dev, "sending version message failed\n");
                goto free_msg;
        }

        err = esd_usb_wait_msg(dev, msg);
        if (err < 0) {
                dev_err(&intf->dev, "no version message answer\n");
                goto free_msg;
        }

        dev->net_count = (int)msg->version_reply.nets;
        dev->version = le32_to_cpu(msg->version_reply.version);

        if (device_create_file(&intf->dev, &dev_attr_firmware))
                dev_err(&intf->dev,
                        "Couldn't create device file for firmware\n");

        if (device_create_file(&intf->dev, &dev_attr_hardware))
                dev_err(&intf->dev,
                        "Couldn't create device file for hardware\n");

        if (device_create_file(&intf->dev, &dev_attr_nets))
                dev_err(&intf->dev,
                        "Couldn't create device file for nets\n");

        /* do per device probing */
        for (i = 0; i < dev->net_count; i++)
                esd_usb_probe_one_net(intf, i);

free_msg:
        kfree(msg);
        if (err)
                kfree(dev);
done:
        return err;
}

/* called by the usb core when the device is removed from the system */
static void esd_usb_disconnect(struct usb_interface *intf)
{
        struct esd_usb *dev = usb_get_intfdata(intf);
        struct net_device *netdev;
        int i;

        device_remove_file(&intf->dev, &dev_attr_firmware);
        device_remove_file(&intf->dev, &dev_attr_hardware);
        device_remove_file(&intf->dev, &dev_attr_nets);

        usb_set_intfdata(intf, NULL);

        if (dev) {
                dev->in_usb_disconnect = 1;
                for (i = 0; i < dev->net_count; i++) {
                        if (dev->nets[i]) {
                                netdev = dev->nets[i]->netdev;
                                netdev_info(netdev, "unregister\n");
                                unregister_netdev(netdev);
                        }
                }
                unlink_all_urbs(dev);
                for (i = 0; i < dev->net_count; i++) {
                        if (dev->nets[i])
                                free_candev(dev->nets[i]->netdev);
                }
                kfree(dev);
        }
}

/* usb specific object needed to register this driver with the usb subsystem */
static struct usb_driver esd_usb_driver = {
        .name = KBUILD_MODNAME,
        .probe = esd_usb_probe,
        .disconnect = esd_usb_disconnect,
        .id_table = esd_usb_table,
};

module_usb_driver(esd_usb_driver);