// SPDX-License-Identifier: GPL-2.0-only
/* CAN driver for Geschwister Schneider USB/CAN devices
 * and bytewerk.org candleLight USB CAN interfaces.
 *
 * Copyright (C) 2013-2016 Geschwister Schneider Technologie-,
 * Entwicklungs- und Vertriebs UG (Haftungsbeschränkt).
 * Copyright (C) 2016 Hubert Denkmair
 * Copyright (c) 2023 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
 *
 * Many thanks to all socketcan devs!
 */

#include <linux/bitfield.h>
#include <linux/clocksource.h>
#include <linux/ethtool.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/signal.h>
#include <linux/timecounter.h>
#include <linux/units.h>
#include <linux/usb.h>
#include <linux/workqueue.h>

#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/error.h>
#include <linux/can/rx-offload.h>

/* Device specific constants */
#define USB_GS_USB_1_VENDOR_ID 0x1d50
#define USB_GS_USB_1_PRODUCT_ID 0x606f

#define USB_CANDLELIGHT_VENDOR_ID 0x1209
#define USB_CANDLELIGHT_PRODUCT_ID 0x2323

#define USB_CES_CANEXT_FD_VENDOR_ID 0x1cd2
#define USB_CES_CANEXT_FD_PRODUCT_ID 0x606f

#define USB_ABE_CANDEBUGGER_FD_VENDOR_ID 0x16d0
#define USB_ABE_CANDEBUGGER_FD_PRODUCT_ID 0x10b8

#define USB_XYLANTA_SAINT3_VENDOR_ID 0x16d0
#define USB_XYLANTA_SAINT3_PRODUCT_ID 0x0f30

#define USB_CANNECTIVITY_VENDOR_ID 0x1209
#define USB_CANNECTIVITY_PRODUCT_ID 0xca01

/* Timestamp 32 bit timer runs at 1 MHz (1 µs tick). Worker accounts
 * for timer overflow (will be after ~71 minutes)
 */
#define GS_USB_TIMESTAMP_TIMER_HZ (1 * HZ_PER_MHZ)
#define GS_USB_TIMESTAMP_WORK_DELAY_SEC 1800
static_assert(GS_USB_TIMESTAMP_WORK_DELAY_SEC <
              CYCLECOUNTER_MASK(32) / GS_USB_TIMESTAMP_TIMER_HZ / 2);

/* Device specific constants */
enum gs_usb_breq {
        GS_USB_BREQ_HOST_FORMAT = 0,
        GS_USB_BREQ_BITTIMING,
        GS_USB_BREQ_MODE,
        GS_USB_BREQ_BERR,
        GS_USB_BREQ_BT_CONST,
        GS_USB_BREQ_DEVICE_CONFIG,
        GS_USB_BREQ_TIMESTAMP,
        GS_USB_BREQ_IDENTIFY,
        GS_USB_BREQ_GET_USER_ID,
        GS_USB_BREQ_QUIRK_CANTACT_PRO_DATA_BITTIMING = GS_USB_BREQ_GET_USER_ID,
        GS_USB_BREQ_SET_USER_ID,
        GS_USB_BREQ_DATA_BITTIMING,
        GS_USB_BREQ_BT_CONST_EXT,
        GS_USB_BREQ_SET_TERMINATION,
        GS_USB_BREQ_GET_TERMINATION,
        GS_USB_BREQ_GET_STATE,
};

enum gs_can_mode {
        /* reset a channel. turns it off */
        GS_CAN_MODE_RESET = 0,
        /* starts a channel */
        GS_CAN_MODE_START
};

enum gs_can_state {
        GS_CAN_STATE_ERROR_ACTIVE = 0,
        GS_CAN_STATE_ERROR_WARNING,
        GS_CAN_STATE_ERROR_PASSIVE,
        GS_CAN_STATE_BUS_OFF,
        GS_CAN_STATE_STOPPED,
        GS_CAN_STATE_SLEEPING
};

enum gs_can_identify_mode {
        GS_CAN_IDENTIFY_OFF = 0,
        GS_CAN_IDENTIFY_ON
};

enum gs_can_termination_state {
        GS_CAN_TERMINATION_STATE_OFF = 0,
        GS_CAN_TERMINATION_STATE_ON
};

#define GS_USB_TERMINATION_DISABLED CAN_TERMINATION_DISABLED
#define GS_USB_TERMINATION_ENABLED 120

/* data types passed between host and device */

/* The firmware on the original USB2CAN by Geschwister Schneider
 * Technologie Entwicklungs- und Vertriebs UG exchanges all data
 * between the host and the device in host byte order. This is done
 * with the struct gs_host_config::byte_order member, which is sent
 * first to indicate the desired byte order.
 *
 * The widely used open source firmware candleLight doesn't support
 * this feature and exchanges the data in little endian byte order.
 */
struct gs_host_config {
        __le32 byte_order;
} __packed;

struct gs_device_config {
        u8 reserved1;
        u8 reserved2;
        u8 reserved3;
        u8 icount;
        __le32 sw_version;
        __le32 hw_version;
} __packed;

#define GS_CAN_MODE_NORMAL 0
#define GS_CAN_MODE_LISTEN_ONLY BIT(0)
#define GS_CAN_MODE_LOOP_BACK BIT(1)
#define GS_CAN_MODE_TRIPLE_SAMPLE BIT(2)
#define GS_CAN_MODE_ONE_SHOT BIT(3)
#define GS_CAN_MODE_HW_TIMESTAMP BIT(4)
/* GS_CAN_FEATURE_IDENTIFY BIT(5) */
/* GS_CAN_FEATURE_USER_ID BIT(6) */
#define GS_CAN_MODE_PAD_PKTS_TO_MAX_PKT_SIZE BIT(7)
#define GS_CAN_MODE_FD BIT(8)
/* GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX BIT(9) */
/* GS_CAN_FEATURE_BT_CONST_EXT BIT(10) */
/* GS_CAN_FEATURE_TERMINATION BIT(11) */
#define GS_CAN_MODE_BERR_REPORTING BIT(12)
/* GS_CAN_FEATURE_GET_STATE BIT(13) */

struct gs_device_mode {
        __le32 mode;
        __le32 flags;
} __packed;

struct gs_device_state {
        __le32 state;
        __le32 rxerr;
        __le32 txerr;
} __packed;

struct gs_device_bittiming {
        __le32 prop_seg;
        __le32 phase_seg1;
        __le32 phase_seg2;
        __le32 sjw;
        __le32 brp;
} __packed;

struct gs_identify_mode {
        __le32 mode;
} __packed;

struct gs_device_termination_state {
        __le32 state;
} __packed;

#define GS_CAN_FEATURE_LISTEN_ONLY BIT(0)
#define GS_CAN_FEATURE_LOOP_BACK BIT(1)
#define GS_CAN_FEATURE_TRIPLE_SAMPLE BIT(2)
#define GS_CAN_FEATURE_ONE_SHOT BIT(3)
#define GS_CAN_FEATURE_HW_TIMESTAMP BIT(4)
#define GS_CAN_FEATURE_IDENTIFY BIT(5)
#define GS_CAN_FEATURE_USER_ID BIT(6)
#define GS_CAN_FEATURE_PAD_PKTS_TO_MAX_PKT_SIZE BIT(7)
#define GS_CAN_FEATURE_FD BIT(8)
#define GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX BIT(9)
#define GS_CAN_FEATURE_BT_CONST_EXT BIT(10)
#define GS_CAN_FEATURE_TERMINATION BIT(11)
#define GS_CAN_FEATURE_BERR_REPORTING BIT(12)
#define GS_CAN_FEATURE_GET_STATE BIT(13)
#define GS_CAN_FEATURE_MASK GENMASK(13, 0)

/* internal quirks - keep in GS_CAN_FEATURE space for now */

/* CANtact Pro original firmware:
 * BREQ DATA_BITTIMING overlaps with GET_USER_ID
 */
#define GS_CAN_FEATURE_QUIRK_BREQ_CANTACT_PRO BIT(31)

struct gs_device_bt_const {
        __le32 feature;
        __le32 fclk_can;
        __le32 tseg1_min;
        __le32 tseg1_max;
        __le32 tseg2_min;
        __le32 tseg2_max;
        __le32 sjw_max;
        __le32 brp_min;
        __le32 brp_max;
        __le32 brp_inc;
} __packed;

struct gs_device_bt_const_extended {
        __le32 feature;
        __le32 fclk_can;
        __le32 tseg1_min;
        __le32 tseg1_max;
        __le32 tseg2_min;
        __le32 tseg2_max;
        __le32 sjw_max;
        __le32 brp_min;
        __le32 brp_max;
        __le32 brp_inc;

        __le32 dtseg1_min;
        __le32 dtseg1_max;
        __le32 dtseg2_min;
        __le32 dtseg2_max;
        __le32 dsjw_max;
        __le32 dbrp_min;
        __le32 dbrp_max;
        __le32 dbrp_inc;
} __packed;

#define GS_CAN_FLAG_OVERFLOW BIT(0)
#define GS_CAN_FLAG_FD BIT(1)
#define GS_CAN_FLAG_BRS BIT(2)
#define GS_CAN_FLAG_ESI BIT(3)

struct classic_can {
        u8 data[8];
} __packed;

struct classic_can_ts {
        u8 data[8];
        __le32 timestamp_us;
} __packed;

struct classic_can_quirk {
        u8 data[8];
        u8 quirk;
} __packed;

struct canfd {
        u8 data[64];
} __packed;

struct canfd_ts {
        u8 data[64];
        __le32 timestamp_us;
} __packed;

struct canfd_quirk {
        u8 data[64];
        u8 quirk;
} __packed;

/* struct gs_host_frame::echo_id == GS_HOST_FRAME_ECHO_ID_RX indicates
 * a regular RX'ed CAN frame
 */
#define GS_HOST_FRAME_ECHO_ID_RX 0xffffffff

struct gs_host_frame {
        struct_group(header,
                u32 echo_id;
                __le32 can_id;

                u8 can_dlc;
                u8 channel;
                u8 flags;
                u8 reserved;
        );

        union {
                DECLARE_FLEX_ARRAY(struct classic_can, classic_can);
                DECLARE_FLEX_ARRAY(struct classic_can_ts, classic_can_ts);
                DECLARE_FLEX_ARRAY(struct classic_can_quirk, classic_can_quirk);
                DECLARE_FLEX_ARRAY(struct canfd, canfd);
                DECLARE_FLEX_ARRAY(struct canfd_ts, canfd_ts);
                DECLARE_FLEX_ARRAY(struct canfd_quirk, canfd_quirk);
        };
} __packed;
/* The GS USB devices make use of the same flags and masks as in
 * linux/can.h and linux/can/error.h, and no additional mapping is necessary.
 */

/* Only send a max of GS_MAX_TX_URBS frames per channel at a time. */
#define GS_MAX_TX_URBS 10
/* Only launch a max of GS_MAX_RX_URBS usb requests at a time. */
#define GS_MAX_RX_URBS 30
#define GS_NAPI_WEIGHT 32

struct gs_tx_context {
        struct gs_can *dev;
        unsigned int echo_id;
};

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

        struct can_rx_offload offload;
        struct gs_usb *parent;

        struct net_device *netdev;
        struct usb_device *udev;

        struct can_bittiming_const bt_const, data_bt_const;
        unsigned int channel;   /* channel number */

        u32 feature;
        unsigned int hf_size_tx;

        /* This lock prevents a race condition between xmit and receive. */
        spinlock_t tx_ctx_lock;
        struct gs_tx_context tx_context[GS_MAX_TX_URBS];

        struct usb_anchor tx_submitted;
        atomic_t active_tx_urbs;
};

/* usb interface struct */
struct gs_usb {
        struct usb_anchor rx_submitted;
        struct usb_device *udev;

        /* time counter for hardware timestamps */
        struct cyclecounter cc;
        struct timecounter tc;
        spinlock_t tc_lock; /* spinlock to guard access tc->cycle_last */
        struct delayed_work timestamp;

        unsigned int hf_size_rx;
        u8 active_channels;
        u8 channel_cnt;

        unsigned int pipe_in;
        unsigned int pipe_out;
        struct gs_can *canch[] __counted_by(channel_cnt);
};

/* 'allocate' a tx context.
 * returns a valid tx context or NULL if there is no space.
 */
static struct gs_tx_context *gs_alloc_tx_context(struct gs_can *dev)
{
        int i = 0;
        unsigned long flags;

        spin_lock_irqsave(&dev->tx_ctx_lock, flags);

        for (; i < GS_MAX_TX_URBS; i++) {
                if (dev->tx_context[i].echo_id == GS_MAX_TX_URBS) {
                        dev->tx_context[i].echo_id = i;
                        spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
                        return &dev->tx_context[i];
                }
        }

        spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
        return NULL;
}

/* releases a tx context
 */
static void gs_free_tx_context(struct gs_tx_context *txc)
{
        txc->echo_id = GS_MAX_TX_URBS;
}

/* Get a tx context by id.
 */
static struct gs_tx_context *gs_get_tx_context(struct gs_can *dev,
                                               unsigned int id)
{
        unsigned long flags;

        if (id < GS_MAX_TX_URBS) {
                spin_lock_irqsave(&dev->tx_ctx_lock, flags);
                if (dev->tx_context[id].echo_id == id) {
                        spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
                        return &dev->tx_context[id];
                }
                spin_unlock_irqrestore(&dev->tx_ctx_lock, flags);
        }
        return NULL;
}

static int gs_cmd_reset(struct gs_can *dev)
{
        struct gs_device_mode dm = {
                .mode = cpu_to_le32(GS_CAN_MODE_RESET),
        };

        return usb_control_msg_send(dev->udev, 0, GS_USB_BREQ_MODE,
                                    USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                    dev->channel, 0, &dm, sizeof(dm), 1000,
                                    GFP_KERNEL);
}

static inline int gs_usb_get_timestamp(const struct gs_usb *parent,
                                       u32 *timestamp_p)
{
        __le32 timestamp;
        int rc;

        rc = usb_control_msg_recv(parent->udev, 0, GS_USB_BREQ_TIMESTAMP,
                                  USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                  0, 0,
                                  &timestamp, sizeof(timestamp),
                                  USB_CTRL_GET_TIMEOUT,
                                  GFP_KERNEL);
        if (rc)
                return rc;

        *timestamp_p = le32_to_cpu(timestamp);

        return 0;
}

static u64 gs_usb_timestamp_read(struct cyclecounter *cc) __must_hold(&dev->tc_lock)
{
        struct gs_usb *parent = container_of(cc, struct gs_usb, cc);
        u32 timestamp = 0;
        int err;

        lockdep_assert_held(&parent->tc_lock);

        /* drop lock for synchronous USB transfer */
        spin_unlock_bh(&parent->tc_lock);
        err = gs_usb_get_timestamp(parent, &timestamp);
        spin_lock_bh(&parent->tc_lock);
        if (err)
                dev_err(&parent->udev->dev,
                        "Error %d while reading timestamp. HW timestamps may be inaccurate.",
                        err);

        return timestamp;
}

static void gs_usb_timestamp_work(struct work_struct *work)
{
        struct delayed_work *delayed_work = to_delayed_work(work);
        struct gs_usb *parent;

        parent = container_of(delayed_work, struct gs_usb, timestamp);
        spin_lock_bh(&parent->tc_lock);
        timecounter_read(&parent->tc);
        spin_unlock_bh(&parent->tc_lock);

        schedule_delayed_work(&parent->timestamp,
                              GS_USB_TIMESTAMP_WORK_DELAY_SEC * HZ);
}

static void gs_usb_skb_set_timestamp(struct gs_can *dev,
                                     struct sk_buff *skb, u32 timestamp)
{
        struct skb_shared_hwtstamps *hwtstamps = skb_hwtstamps(skb);
        struct gs_usb *parent = dev->parent;
        u64 ns;

        spin_lock_bh(&parent->tc_lock);
        ns = timecounter_cyc2time(&parent->tc, timestamp);
        spin_unlock_bh(&parent->tc_lock);

        hwtstamps->hwtstamp = ns_to_ktime(ns);
}

static void gs_usb_timestamp_init(struct gs_usb *parent)
{
        struct cyclecounter *cc = &parent->cc;

        cc->read = gs_usb_timestamp_read;
        cc->mask = CYCLECOUNTER_MASK(32);
        cc->shift = 32 - bits_per(NSEC_PER_SEC / GS_USB_TIMESTAMP_TIMER_HZ);
        cc->mult = clocksource_hz2mult(GS_USB_TIMESTAMP_TIMER_HZ, cc->shift);

        spin_lock_init(&parent->tc_lock);
        spin_lock_bh(&parent->tc_lock);
        timecounter_init(&parent->tc, &parent->cc, ktime_get_real_ns());
        spin_unlock_bh(&parent->tc_lock);

        INIT_DELAYED_WORK(&parent->timestamp, gs_usb_timestamp_work);
        schedule_delayed_work(&parent->timestamp,
                              GS_USB_TIMESTAMP_WORK_DELAY_SEC * HZ);
}

static void gs_usb_timestamp_stop(struct gs_usb *parent)
{
        cancel_delayed_work_sync(&parent->timestamp);
}

static void gs_update_state(struct gs_can *dev, struct can_frame *cf)
{
        struct can_device_stats *can_stats = &dev->can.can_stats;

        if (cf->can_id & CAN_ERR_RESTARTED) {
                dev->can.state = CAN_STATE_ERROR_ACTIVE;
                can_stats->restarts++;
        } else if (cf->can_id & CAN_ERR_BUSOFF) {
                dev->can.state = CAN_STATE_BUS_OFF;
                can_stats->bus_off++;
        } else if (cf->can_id & CAN_ERR_CRTL) {
                if ((cf->data[1] & CAN_ERR_CRTL_TX_WARNING) ||
                    (cf->data[1] & CAN_ERR_CRTL_RX_WARNING)) {
                        dev->can.state = CAN_STATE_ERROR_WARNING;
                        can_stats->error_warning++;
                } else if ((cf->data[1] & CAN_ERR_CRTL_TX_PASSIVE) ||
                           (cf->data[1] & CAN_ERR_CRTL_RX_PASSIVE)) {
                        dev->can.state = CAN_STATE_ERROR_PASSIVE;
                        can_stats->error_passive++;
                } else {
                        dev->can.state = CAN_STATE_ERROR_ACTIVE;
                }
        }
}

static u32 gs_usb_set_timestamp(struct gs_can *dev, struct sk_buff *skb,
                                const struct gs_host_frame *hf)
{
        u32 timestamp;

        if (hf->flags & GS_CAN_FLAG_FD)
                timestamp = le32_to_cpu(hf->canfd_ts->timestamp_us);
        else
                timestamp = le32_to_cpu(hf->classic_can_ts->timestamp_us);

        if (skb)
                gs_usb_skb_set_timestamp(dev, skb, timestamp);

        return timestamp;
}

static void gs_usb_rx_offload(struct gs_can *dev, struct sk_buff *skb,
                              const struct gs_host_frame *hf)
{
        struct can_rx_offload *offload = &dev->offload;
        int rc;

        if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP) {
                const u32 ts = gs_usb_set_timestamp(dev, skb, hf);

                rc = can_rx_offload_queue_timestamp(offload, skb, ts);
        } else {
                rc = can_rx_offload_queue_tail(offload, skb);
        }

        if (rc)
                dev->netdev->stats.rx_fifo_errors++;
}

static unsigned int
gs_usb_get_echo_skb(struct gs_can *dev, struct sk_buff *skb,
                    const struct gs_host_frame *hf)
{
        struct can_rx_offload *offload = &dev->offload;
        const u32 echo_id = hf->echo_id;
        unsigned int len;

        if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP) {
                const u32 ts = gs_usb_set_timestamp(dev, skb, hf);

                len = can_rx_offload_get_echo_skb_queue_timestamp(offload, echo_id,
                                                                  ts, NULL);
        } else {
                len = can_rx_offload_get_echo_skb_queue_tail(offload, echo_id,
                                                             NULL);
        }

        return len;
}

static unsigned int
gs_usb_get_minimum_rx_length(const struct gs_can *dev, const struct gs_host_frame *hf,
                             unsigned int *data_length_p)
{
        unsigned int minimum_length, data_length = 0;

        if (hf->flags & GS_CAN_FLAG_FD) {
                if (hf->echo_id == GS_HOST_FRAME_ECHO_ID_RX)
                        data_length = can_fd_dlc2len(hf->can_dlc);

                if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
                        /* timestamp follows data field of max size */
                        minimum_length = struct_size(hf, canfd_ts, 1);
                else
                        minimum_length = sizeof(hf->header) + data_length;
        } else {
                if (hf->echo_id == GS_HOST_FRAME_ECHO_ID_RX &&
                    !(hf->can_id & cpu_to_le32(CAN_RTR_FLAG)))
                        data_length = can_cc_dlc2len(hf->can_dlc);

                if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
                        /* timestamp follows data field of max size */
                        minimum_length = struct_size(hf, classic_can_ts, 1);
                else
                        minimum_length = sizeof(hf->header) + data_length;
        }

        *data_length_p = data_length;
        return minimum_length;
}

static void gs_usb_receive_bulk_callback(struct urb *urb)
{
        struct gs_usb *parent = urb->context;
        struct gs_can *dev;
        struct net_device *netdev = NULL;
        int rc;
        struct net_device_stats *stats;
        struct gs_host_frame *hf = urb->transfer_buffer;
        unsigned int minimum_length, data_length;
        struct gs_tx_context *txc;
        struct can_frame *cf;
        struct canfd_frame *cfd;
        struct sk_buff *skb;

        BUG_ON(!parent);

        switch (urb->status) {
        case 0: /* success */
                break;
        case -ENOENT:
        case -ESHUTDOWN:
                return;
        default:
                /* do not resubmit aborted urbs. eg: when device goes down */
                return;
        }

        minimum_length = sizeof(hf->header);
        if (urb->actual_length < minimum_length) {
                dev_err_ratelimited(&parent->udev->dev,
                                    "short read (actual_length=%u, minimum_length=%u)\n",
                                    urb->actual_length, minimum_length);

                goto resubmit_urb;
        }

        /* device reports out of range channel id */
        if (hf->channel >= parent->channel_cnt)
                goto device_detach;

        dev = parent->canch[hf->channel];

        netdev = dev->netdev;
        stats = &netdev->stats;

        if (!netif_device_present(netdev))
                return;

        if (!netif_running(netdev))
                goto resubmit_urb;

        minimum_length = gs_usb_get_minimum_rx_length(dev, hf, &data_length);
        if (urb->actual_length < minimum_length) {
                stats->rx_errors++;
                stats->rx_length_errors++;

                if (net_ratelimit())
                        netdev_err(netdev,
                                   "short read (actual_length=%u, minimum_length=%u)\n",
                                   urb->actual_length, minimum_length);

                goto resubmit_urb;
        }

        if (hf->echo_id == GS_HOST_FRAME_ECHO_ID_RX) { /* normal rx */
                if (hf->flags & GS_CAN_FLAG_FD) {
                        skb = alloc_canfd_skb(netdev, &cfd);
                        if (!skb)
                                return;

                        cfd->can_id = le32_to_cpu(hf->can_id);
                        cfd->len = data_length;
                        if (hf->flags & GS_CAN_FLAG_BRS)
                                cfd->flags |= CANFD_BRS;
                        if (hf->flags & GS_CAN_FLAG_ESI)
                                cfd->flags |= CANFD_ESI;

                        memcpy(cfd->data, hf->canfd->data, data_length);
                } else {
                        skb = alloc_can_skb(netdev, &cf);
                        if (!skb)
                                return;

                        cf->can_id = le32_to_cpu(hf->can_id);
                        can_frame_set_cc_len(cf, hf->can_dlc, dev->can.ctrlmode);

                        memcpy(cf->data, hf->classic_can->data, data_length);

                        /* ERROR frames tell us information about the controller */
                        if (le32_to_cpu(hf->can_id) & CAN_ERR_FLAG)
                                gs_update_state(dev, cf);
                }

                gs_usb_rx_offload(dev, skb, hf);
        } else { /* echo_id == hf->echo_id */
                if (hf->echo_id >= GS_MAX_TX_URBS) {
                        netdev_err(netdev,
                                   "Unexpected out of range echo id %u\n",
                                   hf->echo_id);
                        goto resubmit_urb;
                }

                txc = gs_get_tx_context(dev, hf->echo_id);

                /* bad devices send bad echo_ids. */
                if (!txc) {
                        netdev_err(netdev,
                                   "Unexpected unused echo id %u\n",
                                   hf->echo_id);
                        goto resubmit_urb;
                }

                skb = dev->can.echo_skb[hf->echo_id];
                stats->tx_packets++;
                stats->tx_bytes += gs_usb_get_echo_skb(dev, skb, hf);
                gs_free_tx_context(txc);

                atomic_dec(&dev->active_tx_urbs);

                netif_wake_queue(netdev);
        }

        if (hf->flags & GS_CAN_FLAG_OVERFLOW) {
                stats->rx_over_errors++;
                stats->rx_errors++;

                skb = alloc_can_err_skb(netdev, &cf);
                if (!skb)
                        goto resubmit_urb;

                cf->can_id |= CAN_ERR_CRTL;
                cf->len = CAN_ERR_DLC;
                cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;

                gs_usb_rx_offload(dev, skb, hf);
        }

        can_rx_offload_irq_finish(&dev->offload);

resubmit_urb:
        usb_fill_bulk_urb(urb, parent->udev,
                          parent->pipe_in,
                          hf, parent->hf_size_rx,
                          gs_usb_receive_bulk_callback, parent);

        usb_anchor_urb(urb, &parent->rx_submitted);

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

        usb_unanchor_urb(urb);

        /* USB failure take down all interfaces */
        if (rc == -ENODEV) {
device_detach:
                for (rc = 0; rc < parent->channel_cnt; rc++) {
                        if (parent->canch[rc])
                                netif_device_detach(parent->canch[rc]->netdev);
                }
        } else if (rc != -ESHUTDOWN && net_ratelimit()) {
                netdev_info(netdev, "failed to re-submit IN URB: %pe\n",
                            ERR_PTR(rc));
        }
}

static int gs_usb_set_bittiming(struct gs_can *dev)
{
        struct can_bittiming *bt = &dev->can.bittiming;
        struct gs_device_bittiming dbt = {
                .prop_seg = cpu_to_le32(bt->prop_seg),
                .phase_seg1 = cpu_to_le32(bt->phase_seg1),
                .phase_seg2 = cpu_to_le32(bt->phase_seg2),
                .sjw = cpu_to_le32(bt->sjw),
                .brp = cpu_to_le32(bt->brp),
        };

        /* request bit timings */
        return usb_control_msg_send(dev->udev, 0, GS_USB_BREQ_BITTIMING,
                                    USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                    dev->channel, 0, &dbt, sizeof(dbt), 1000,
                                    GFP_KERNEL);
}

static int gs_usb_set_data_bittiming(struct gs_can *dev)
{
        struct can_bittiming *bt = &dev->can.fd.data_bittiming;
        struct gs_device_bittiming dbt = {
                .prop_seg = cpu_to_le32(bt->prop_seg),
                .phase_seg1 = cpu_to_le32(bt->phase_seg1),
                .phase_seg2 = cpu_to_le32(bt->phase_seg2),
                .sjw = cpu_to_le32(bt->sjw),
                .brp = cpu_to_le32(bt->brp),
        };
        u8 request = GS_USB_BREQ_DATA_BITTIMING;

        if (dev->feature & GS_CAN_FEATURE_QUIRK_BREQ_CANTACT_PRO)
                request = GS_USB_BREQ_QUIRK_CANTACT_PRO_DATA_BITTIMING;

        /* request data bit timings */
        return usb_control_msg_send(dev->udev, 0, request,
                                    USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                    dev->channel, 0, &dbt, sizeof(dbt), 1000,
                                    GFP_KERNEL);
}

static void gs_usb_xmit_callback(struct urb *urb)
{
        struct gs_tx_context *txc = urb->context;
        struct gs_can *dev = txc->dev;
        struct net_device *netdev = dev->netdev;

        if (!urb->status)
                return;

        if (urb->status != -ESHUTDOWN && net_ratelimit())
                netdev_info(netdev, "failed to xmit URB %u: %pe\n",
                            txc->echo_id, ERR_PTR(urb->status));

        netdev->stats.tx_dropped++;
        netdev->stats.tx_errors++;

        can_free_echo_skb(netdev, txc->echo_id, NULL);
        gs_free_tx_context(txc);
        atomic_dec(&dev->active_tx_urbs);

        netif_wake_queue(netdev);
}

static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
                                     struct net_device *netdev)
{
        struct gs_can *dev = netdev_priv(netdev);
        struct net_device_stats *stats = &dev->netdev->stats;
        struct urb *urb;
        struct gs_host_frame *hf;
        struct can_frame *cf;
        struct canfd_frame *cfd;
        int rc;
        unsigned int idx;
        struct gs_tx_context *txc;

        if (can_dev_dropped_skb(netdev, skb))
                return NETDEV_TX_OK;

        /* find an empty context to keep track of transmission */
        txc = gs_alloc_tx_context(dev);
        if (!txc)
                return NETDEV_TX_BUSY;

        /* create a URB, and a buffer for it */
        urb = usb_alloc_urb(0, GFP_ATOMIC);
        if (!urb)
                goto nomem_urb;

        hf = kmalloc(dev->hf_size_tx, GFP_ATOMIC);
        if (!hf)
                goto nomem_hf;

        idx = txc->echo_id;

        if (idx >= GS_MAX_TX_URBS) {
                netdev_err(netdev, "Invalid tx context %u\n", idx);
                goto badidx;
        }

        hf->echo_id = idx;
        hf->channel = dev->channel;
        hf->flags = 0;
        hf->reserved = 0;

        if (can_is_canfd_skb(skb)) {
                cfd = (struct canfd_frame *)skb->data;

                hf->can_id = cpu_to_le32(cfd->can_id);
                hf->can_dlc = can_fd_len2dlc(cfd->len);
                hf->flags |= GS_CAN_FLAG_FD;
                if (cfd->flags & CANFD_BRS)
                        hf->flags |= GS_CAN_FLAG_BRS;
                if (cfd->flags & CANFD_ESI)
                        hf->flags |= GS_CAN_FLAG_ESI;

                memcpy(hf->canfd->data, cfd->data, cfd->len);
        } else {
                cf = (struct can_frame *)skb->data;

                hf->can_id = cpu_to_le32(cf->can_id);
                hf->can_dlc = can_get_cc_dlc(cf, dev->can.ctrlmode);

                memcpy(hf->classic_can->data, cf->data, cf->len);
        }

        usb_fill_bulk_urb(urb, dev->udev,
                          dev->parent->pipe_out,
                          hf, dev->hf_size_tx,
                          gs_usb_xmit_callback, txc);

        urb->transfer_flags |= URB_FREE_BUFFER;
        usb_anchor_urb(urb, &dev->tx_submitted);

        can_put_echo_skb(skb, netdev, idx, 0);

        atomic_inc(&dev->active_tx_urbs);

        rc = usb_submit_urb(urb, GFP_ATOMIC);
        if (unlikely(rc)) {                     /* usb send failed */
                atomic_dec(&dev->active_tx_urbs);

                can_free_echo_skb(netdev, idx, NULL);
                gs_free_tx_context(txc);

                usb_unanchor_urb(urb);

                if (rc == -ENODEV) {
                        netif_device_detach(netdev);
                } else {
                        netdev_err(netdev, "usb_submit failed (err=%d)\n", rc);
                        stats->tx_dropped++;
                }
        } else {
                /* Slow down tx path */
                if (atomic_read(&dev->active_tx_urbs) >= GS_MAX_TX_URBS)
                        netif_stop_queue(netdev);
        }

        /* let usb core take care of this urb */
        usb_free_urb(urb);

        return NETDEV_TX_OK;

badidx:
        kfree(hf);
nomem_hf:
        usb_free_urb(urb);

nomem_urb:
        gs_free_tx_context(txc);
        dev_kfree_skb(skb);
        stats->tx_dropped++;
        return NETDEV_TX_OK;
}

static int gs_can_open(struct net_device *netdev)
{
        struct gs_can *dev = netdev_priv(netdev);
        struct gs_usb *parent = dev->parent;
        struct gs_device_mode dm = {
                .mode = cpu_to_le32(GS_CAN_MODE_START),
        };
        struct gs_host_frame *hf;
        struct urb *urb = NULL;
        u32 ctrlmode;
        u32 flags = 0;
        int rc, i;

        rc = open_candev(netdev);
        if (rc)
                return rc;

        ctrlmode = dev->can.ctrlmode;
        if (ctrlmode & CAN_CTRLMODE_FD) {
                if (dev->feature & GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX)
                        dev->hf_size_tx = struct_size(hf, canfd_quirk, 1);
                else
                        dev->hf_size_tx = struct_size(hf, canfd, 1);
        } else {
                if (dev->feature & GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX)
                        dev->hf_size_tx = struct_size(hf, classic_can_quirk, 1);
                else
                        dev->hf_size_tx = struct_size(hf, classic_can, 1);
        }

        can_rx_offload_enable(&dev->offload);

        if (!parent->active_channels) {
                if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
                        gs_usb_timestamp_init(parent);

                for (i = 0; i < GS_MAX_RX_URBS; i++) {
                        u8 *buf;

                        /* alloc rx urb */
                        urb = usb_alloc_urb(0, GFP_KERNEL);
                        if (!urb) {
                                rc = -ENOMEM;
                                goto out_usb_kill_anchored_urbs;
                        }

                        /* alloc rx buffer */
                        buf = kmalloc(dev->parent->hf_size_rx,
                                      GFP_KERNEL);
                        if (!buf) {
                                rc = -ENOMEM;
                                goto out_usb_free_urb;
                        }

                        /* fill, anchor, and submit rx urb */
                        usb_fill_bulk_urb(urb,
                                          dev->udev,
                                          dev->parent->pipe_in,
                                          buf,
                                          dev->parent->hf_size_rx,
                                          gs_usb_receive_bulk_callback, parent);
                        urb->transfer_flags |= URB_FREE_BUFFER;

                        usb_anchor_urb(urb, &parent->rx_submitted);

                        rc = usb_submit_urb(urb, GFP_KERNEL);
                        if (rc) {
                                if (rc == -ENODEV)
                                        netif_device_detach(dev->netdev);

                                netdev_err(netdev,
                                           "usb_submit_urb() failed, error %pe\n",
                                           ERR_PTR(rc));

                                goto out_usb_unanchor_urb;
                        }

                        /* Drop reference,
                         * USB core will take care of freeing it
                         */
                        usb_free_urb(urb);
                }
        }

        /* flags */
        if (ctrlmode & CAN_CTRLMODE_LOOPBACK)
                flags |= GS_CAN_MODE_LOOP_BACK;

        if (ctrlmode & CAN_CTRLMODE_LISTENONLY)
                flags |= GS_CAN_MODE_LISTEN_ONLY;

        if (ctrlmode & CAN_CTRLMODE_3_SAMPLES)
                flags |= GS_CAN_MODE_TRIPLE_SAMPLE;

        if (ctrlmode & CAN_CTRLMODE_ONE_SHOT)
                flags |= GS_CAN_MODE_ONE_SHOT;

        if (ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
                flags |= GS_CAN_MODE_BERR_REPORTING;

        if (ctrlmode & CAN_CTRLMODE_FD)
                flags |= GS_CAN_MODE_FD;

        /* if hardware supports timestamps, enable it */
        if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
                flags |= GS_CAN_MODE_HW_TIMESTAMP;

        rc = gs_usb_set_bittiming(dev);
        if (rc) {
                netdev_err(netdev, "failed to set bittiming: %pe\n", ERR_PTR(rc));
                goto out_usb_kill_anchored_urbs;
        }

        if (ctrlmode & CAN_CTRLMODE_FD) {
                rc = gs_usb_set_data_bittiming(dev);
                if (rc) {
                        netdev_err(netdev, "failed to set data bittiming: %pe\n", ERR_PTR(rc));
                        goto out_usb_kill_anchored_urbs;
                }
        }

        /* finally start device */
        dev->can.state = CAN_STATE_ERROR_ACTIVE;
        dm.flags = cpu_to_le32(flags);
        rc = usb_control_msg_send(dev->udev, 0, GS_USB_BREQ_MODE,
                                  USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                  dev->channel, 0, &dm, sizeof(dm), 1000,
                                  GFP_KERNEL);
        if (rc) {
                netdev_err(netdev, "Couldn't start device (err=%d)\n", rc);
                dev->can.state = CAN_STATE_STOPPED;

                goto out_usb_kill_anchored_urbs;
        }

        parent->active_channels++;
        if (!(dev->can.ctrlmode & CAN_CTRLMODE_LISTENONLY))
                netif_start_queue(netdev);

        return 0;

out_usb_unanchor_urb:
        usb_unanchor_urb(urb);
out_usb_free_urb:
        usb_free_urb(urb);
out_usb_kill_anchored_urbs:
        if (!parent->active_channels) {
                usb_kill_anchored_urbs(&parent->rx_submitted);

                if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
                        gs_usb_timestamp_stop(parent);
        }

        can_rx_offload_disable(&dev->offload);
        close_candev(netdev);

        return rc;
}

static int gs_usb_get_state(const struct net_device *netdev,
                            struct can_berr_counter *bec,
                            enum can_state *state)
{
        struct gs_can *dev = netdev_priv(netdev);
        struct gs_device_state ds;
        int rc;

        rc = usb_control_msg_recv(dev->udev, 0, GS_USB_BREQ_GET_STATE,
                                  USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                  dev->channel, 0,
                                  &ds, sizeof(ds),
                                  USB_CTRL_GET_TIMEOUT,
                                  GFP_KERNEL);
        if (rc)
                return rc;

        if (le32_to_cpu(ds.state) >= CAN_STATE_MAX)
                return -EOPNOTSUPP;

        *state = le32_to_cpu(ds.state);
        bec->txerr = le32_to_cpu(ds.txerr);
        bec->rxerr = le32_to_cpu(ds.rxerr);

        return 0;
}

static int gs_usb_can_get_berr_counter(const struct net_device *netdev,
                                       struct can_berr_counter *bec)
{
        enum can_state state;

        return gs_usb_get_state(netdev, bec, &state);
}

static int gs_can_close(struct net_device *netdev)
{
        int rc;
        struct gs_can *dev = netdev_priv(netdev);
        struct gs_usb *parent = dev->parent;

        netif_stop_queue(netdev);

        /* Stop polling */
        parent->active_channels--;
        if (!parent->active_channels) {
                usb_kill_anchored_urbs(&parent->rx_submitted);

                if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
                        gs_usb_timestamp_stop(parent);
        }

        /* Stop sending URBs */
        usb_kill_anchored_urbs(&dev->tx_submitted);
        atomic_set(&dev->active_tx_urbs, 0);

        dev->can.state = CAN_STATE_STOPPED;

        /* reset the device */
        gs_cmd_reset(dev);

        /* reset tx contexts */
        for (rc = 0; rc < GS_MAX_TX_URBS; rc++) {
                dev->tx_context[rc].dev = dev;
                dev->tx_context[rc].echo_id = GS_MAX_TX_URBS;
        }

        can_rx_offload_disable(&dev->offload);

        /* close the netdev */
        close_candev(netdev);

        return 0;
}

static int gs_can_hwtstamp_get(struct net_device *netdev,
                               struct kernel_hwtstamp_config *cfg)
{
        const struct gs_can *dev = netdev_priv(netdev);

        if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
                return can_hwtstamp_get(netdev, cfg);

        return -EOPNOTSUPP;
}

static int gs_can_hwtstamp_set(struct net_device *netdev,
                               struct kernel_hwtstamp_config *cfg,
                               struct netlink_ext_ack *extack)
{
        const struct gs_can *dev = netdev_priv(netdev);

        if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
                return can_hwtstamp_set(netdev, cfg, extack);

        return -EOPNOTSUPP;
}

static const struct net_device_ops gs_usb_netdev_ops = {
        .ndo_open = gs_can_open,
        .ndo_stop = gs_can_close,
        .ndo_start_xmit = gs_can_start_xmit,
        .ndo_hwtstamp_get = gs_can_hwtstamp_get,
        .ndo_hwtstamp_set = gs_can_hwtstamp_set,
};

static int gs_usb_set_identify(struct net_device *netdev, bool do_identify)
{
        struct gs_can *dev = netdev_priv(netdev);
        struct gs_identify_mode imode;

        if (do_identify)
                imode.mode = cpu_to_le32(GS_CAN_IDENTIFY_ON);
        else
                imode.mode = cpu_to_le32(GS_CAN_IDENTIFY_OFF);

        return usb_control_msg_send(dev->udev, 0, GS_USB_BREQ_IDENTIFY,
                                    USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                    dev->channel, 0, &imode, sizeof(imode), 100,
                                    GFP_KERNEL);
}

/* blink LED's for finding the this interface */
static int gs_usb_set_phys_id(struct net_device *netdev,
                              enum ethtool_phys_id_state state)
{
        const struct gs_can *dev = netdev_priv(netdev);
        int rc = 0;

        if (!(dev->feature & GS_CAN_FEATURE_IDENTIFY))
                return -EOPNOTSUPP;

        switch (state) {
        case ETHTOOL_ID_ACTIVE:
                rc = gs_usb_set_identify(netdev, GS_CAN_IDENTIFY_ON);
                break;
        case ETHTOOL_ID_INACTIVE:
                rc = gs_usb_set_identify(netdev, GS_CAN_IDENTIFY_OFF);
                break;
        default:
                break;
        }

        return rc;
}

static int gs_usb_get_ts_info(struct net_device *netdev,
                              struct kernel_ethtool_ts_info *info)
{
        struct gs_can *dev = netdev_priv(netdev);

        /* report if device supports HW timestamps */
        if (dev->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
                return can_ethtool_op_get_ts_info_hwts(netdev, info);

        return ethtool_op_get_ts_info(netdev, info);
}

static const struct ethtool_ops gs_usb_ethtool_ops = {
        .set_phys_id = gs_usb_set_phys_id,
        .get_ts_info = gs_usb_get_ts_info,
};

static int gs_usb_get_termination(struct net_device *netdev, u16 *term)
{
        struct gs_can *dev = netdev_priv(netdev);
        struct gs_device_termination_state term_state;
        int rc;

        rc = usb_control_msg_recv(dev->udev, 0, GS_USB_BREQ_GET_TERMINATION,
                                  USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                  dev->channel, 0,
                                  &term_state, sizeof(term_state), 1000,
                                  GFP_KERNEL);
        if (rc)
                return rc;

        if (term_state.state == cpu_to_le32(GS_CAN_TERMINATION_STATE_ON))
                *term = GS_USB_TERMINATION_ENABLED;
        else
                *term = GS_USB_TERMINATION_DISABLED;

        return 0;
}

static int gs_usb_set_termination(struct net_device *netdev, u16 term)
{
        struct gs_can *dev = netdev_priv(netdev);
        struct gs_device_termination_state term_state;

        if (term == GS_USB_TERMINATION_ENABLED)
                term_state.state = cpu_to_le32(GS_CAN_TERMINATION_STATE_ON);
        else
                term_state.state = cpu_to_le32(GS_CAN_TERMINATION_STATE_OFF);

        return usb_control_msg_send(dev->udev, 0, GS_USB_BREQ_SET_TERMINATION,
                                    USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                    dev->channel, 0,
                                    &term_state, sizeof(term_state), 1000,
                                    GFP_KERNEL);
}

static const u16 gs_usb_termination_const[] = {
        GS_USB_TERMINATION_DISABLED,
        GS_USB_TERMINATION_ENABLED
};

static struct gs_can *gs_make_candev(unsigned int channel,
                                     struct usb_interface *intf,
                                     struct gs_device_config *dconf)
{
        struct gs_can *dev;
        struct net_device *netdev;
        int rc;
        struct gs_device_bt_const_extended bt_const_extended;
        struct gs_device_bt_const bt_const;
        u32 feature;

        /* fetch bit timing constants */
        rc = usb_control_msg_recv(interface_to_usbdev(intf), 0,
                                  GS_USB_BREQ_BT_CONST,
                                  USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                  channel, 0, &bt_const, sizeof(bt_const), 1000,
                                  GFP_KERNEL);

        if (rc) {
                dev_err(&intf->dev,
                        "Couldn't get bit timing const for channel %d (%pe)\n",
                        channel, ERR_PTR(rc));
                return ERR_PTR(rc);
        }

        /* create netdev */
        netdev = alloc_candev(sizeof(struct gs_can), GS_MAX_TX_URBS);
        if (!netdev) {
                dev_err(&intf->dev, "Couldn't allocate candev\n");
                return ERR_PTR(-ENOMEM);
        }

        dev = netdev_priv(netdev);

        netdev->netdev_ops = &gs_usb_netdev_ops;
        netdev->ethtool_ops = &gs_usb_ethtool_ops;

        netdev->flags |= IFF_ECHO; /* we support full roundtrip echo */
        netdev->dev_id = channel;
        netdev->dev_port = channel;

        /* dev setup */
        strcpy(dev->bt_const.name, KBUILD_MODNAME);
        dev->bt_const.tseg1_min = le32_to_cpu(bt_const.tseg1_min);
        dev->bt_const.tseg1_max = le32_to_cpu(bt_const.tseg1_max);
        dev->bt_const.tseg2_min = le32_to_cpu(bt_const.tseg2_min);
        dev->bt_const.tseg2_max = le32_to_cpu(bt_const.tseg2_max);
        dev->bt_const.sjw_max = le32_to_cpu(bt_const.sjw_max);
        dev->bt_const.brp_min = le32_to_cpu(bt_const.brp_min);
        dev->bt_const.brp_max = le32_to_cpu(bt_const.brp_max);
        dev->bt_const.brp_inc = le32_to_cpu(bt_const.brp_inc);

        dev->udev = interface_to_usbdev(intf);
        dev->netdev = netdev;
        dev->channel = channel;

        init_usb_anchor(&dev->tx_submitted);
        atomic_set(&dev->active_tx_urbs, 0);
        spin_lock_init(&dev->tx_ctx_lock);
        for (rc = 0; rc < GS_MAX_TX_URBS; rc++) {
                dev->tx_context[rc].dev = dev;
                dev->tx_context[rc].echo_id = GS_MAX_TX_URBS;
        }

        /* can setup */
        dev->can.state = CAN_STATE_STOPPED;
        dev->can.clock.freq = le32_to_cpu(bt_const.fclk_can);
        dev->can.bittiming_const = &dev->bt_const;

        dev->can.ctrlmode_supported = CAN_CTRLMODE_CC_LEN8_DLC;

        feature = le32_to_cpu(bt_const.feature);
        dev->feature = FIELD_GET(GS_CAN_FEATURE_MASK, feature);
        if (feature & GS_CAN_FEATURE_LISTEN_ONLY)
                dev->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;

        if (feature & GS_CAN_FEATURE_LOOP_BACK)
                dev->can.ctrlmode_supported |= CAN_CTRLMODE_LOOPBACK;

        if (feature & GS_CAN_FEATURE_TRIPLE_SAMPLE)
                dev->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;

        if (feature & GS_CAN_FEATURE_ONE_SHOT)
                dev->can.ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT;

        if (feature & GS_CAN_FEATURE_FD) {
                dev->can.ctrlmode_supported |= CAN_CTRLMODE_FD;
                /* The data bit timing will be overwritten, if
                 * GS_CAN_FEATURE_BT_CONST_EXT is set.
                 */
                dev->can.fd.data_bittiming_const = &dev->bt_const;
        }

        if (feature & GS_CAN_FEATURE_TERMINATION) {
                rc = gs_usb_get_termination(netdev, &dev->can.termination);
                if (rc) {
                        dev->feature &= ~GS_CAN_FEATURE_TERMINATION;

                        dev_info(&intf->dev,
                                 "Disabling termination support for channel %d (%pe)\n",
                                 channel, ERR_PTR(rc));
                } else {
                        dev->can.termination_const = gs_usb_termination_const;
                        dev->can.termination_const_cnt = ARRAY_SIZE(gs_usb_termination_const);
                        dev->can.do_set_termination = gs_usb_set_termination;
                }
        }

        if (feature & GS_CAN_FEATURE_BERR_REPORTING)
                dev->can.ctrlmode_supported |= CAN_CTRLMODE_BERR_REPORTING;

        if (feature & GS_CAN_FEATURE_GET_STATE)
                dev->can.do_get_berr_counter = gs_usb_can_get_berr_counter;

        /* The CANtact Pro from LinkLayer Labs is based on the
         * LPC54616 µC, which is affected by the NXP LPC USB transfer
         * erratum. However, the current firmware (version 2) doesn't
         * set the GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX bit. Set the
         * feature GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX to workaround
         * this issue.
         *
         * For the GS_USB_BREQ_DATA_BITTIMING USB control message the
         * CANtact Pro firmware uses a request value, which is already
         * used by the candleLight firmware for a different purpose
         * (GS_USB_BREQ_GET_USER_ID). Set the feature
         * GS_CAN_FEATURE_QUIRK_BREQ_CANTACT_PRO to workaround this
         * issue.
         */
        if (dev->udev->descriptor.idVendor == cpu_to_le16(USB_GS_USB_1_VENDOR_ID) &&
            dev->udev->descriptor.idProduct == cpu_to_le16(USB_GS_USB_1_PRODUCT_ID) &&
            dev->udev->manufacturer && dev->udev->product &&
            !strcmp(dev->udev->manufacturer, "LinkLayer Labs") &&
            !strcmp(dev->udev->product, "CANtact Pro") &&
            (le32_to_cpu(dconf->sw_version) <= 2))
                dev->feature |= GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX |
                        GS_CAN_FEATURE_QUIRK_BREQ_CANTACT_PRO;

        /* GS_CAN_FEATURE_IDENTIFY is only supported for sw_version > 1 */
        if (!(le32_to_cpu(dconf->sw_version) > 1 &&
              feature & GS_CAN_FEATURE_IDENTIFY))
                dev->feature &= ~GS_CAN_FEATURE_IDENTIFY;

        /* fetch extended bit timing constants if device has feature
         * GS_CAN_FEATURE_FD and GS_CAN_FEATURE_BT_CONST_EXT
         */
        if (feature & GS_CAN_FEATURE_FD &&
            feature & GS_CAN_FEATURE_BT_CONST_EXT) {
                rc = usb_control_msg_recv(interface_to_usbdev(intf), 0,
                                          GS_USB_BREQ_BT_CONST_EXT,
                                          USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                          channel, 0, &bt_const_extended,
                                          sizeof(bt_const_extended),
                                          1000, GFP_KERNEL);
                if (rc) {
                        dev_err(&intf->dev,
                                "Couldn't get extended bit timing const for channel %d (%pe)\n",
                                channel, ERR_PTR(rc));
                        goto out_free_candev;
                }

                strcpy(dev->data_bt_const.name, KBUILD_MODNAME);
                dev->data_bt_const.tseg1_min = le32_to_cpu(bt_const_extended.dtseg1_min);
                dev->data_bt_const.tseg1_max = le32_to_cpu(bt_const_extended.dtseg1_max);
                dev->data_bt_const.tseg2_min = le32_to_cpu(bt_const_extended.dtseg2_min);
                dev->data_bt_const.tseg2_max = le32_to_cpu(bt_const_extended.dtseg2_max);
                dev->data_bt_const.sjw_max = le32_to_cpu(bt_const_extended.dsjw_max);
                dev->data_bt_const.brp_min = le32_to_cpu(bt_const_extended.dbrp_min);
                dev->data_bt_const.brp_max = le32_to_cpu(bt_const_extended.dbrp_max);
                dev->data_bt_const.brp_inc = le32_to_cpu(bt_const_extended.dbrp_inc);

                dev->can.fd.data_bittiming_const = &dev->data_bt_const;
        }

        can_rx_offload_add_manual(netdev, &dev->offload, GS_NAPI_WEIGHT);
        SET_NETDEV_DEV(netdev, &intf->dev);

        rc = register_candev(dev->netdev);
        if (rc) {
                dev_err(&intf->dev,
                        "Couldn't register candev for channel %d (%pe)\n",
                        channel, ERR_PTR(rc));
                goto out_can_rx_offload_del;
        }

        return dev;

out_can_rx_offload_del:
        can_rx_offload_del(&dev->offload);
out_free_candev:
        free_candev(dev->netdev);
        return ERR_PTR(rc);
}

static void gs_destroy_candev(struct gs_can *dev)
{
        unregister_candev(dev->netdev);
        can_rx_offload_del(&dev->offload);
        free_candev(dev->netdev);
}

static int gs_usb_probe(struct usb_interface *intf,
                        const struct usb_device_id *id)
{
        struct usb_device *udev = interface_to_usbdev(intf);
        struct usb_endpoint_descriptor *ep_in, *ep_out;
        struct gs_host_frame *hf;
        struct gs_usb *parent;
        struct gs_host_config hconf = {
                .byte_order = cpu_to_le32(0x0000beef),
        };
        struct gs_device_config dconf;
        unsigned int icount, i;
        int rc;

        rc = usb_find_common_endpoints(intf->cur_altsetting,
                                       &ep_in, &ep_out, NULL, NULL);
        if (rc) {
                dev_err(&intf->dev, "Required endpoints not found\n");
                return rc;
        }

        /* send host config */
        rc = usb_control_msg_send(udev, 0,
                                  GS_USB_BREQ_HOST_FORMAT,
                                  USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                  1, intf->cur_altsetting->desc.bInterfaceNumber,
                                  &hconf, sizeof(hconf), 1000,
                                  GFP_KERNEL);
        if (rc) {
                dev_err(&intf->dev, "Couldn't send data format (err=%d)\n", rc);
                return rc;
        }

        /* read device config */
        rc = usb_control_msg_recv(udev, 0,
                                  GS_USB_BREQ_DEVICE_CONFIG,
                                  USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                  1, intf->cur_altsetting->desc.bInterfaceNumber,
                                  &dconf, sizeof(dconf), 1000,
                                  GFP_KERNEL);
        if (rc) {
                dev_err(&intf->dev, "Couldn't get device config: (err=%d)\n",
                        rc);
                return rc;
        }

        icount = dconf.icount + 1;
        dev_info(&intf->dev, "Configuring for %u interfaces\n", icount);

        if (icount > type_max(parent->channel_cnt)) {
                dev_err(&intf->dev,
                        "Driver cannot handle more that %u CAN interfaces\n",
                        type_max(parent->channel_cnt));
                return -EINVAL;
        }

        parent = kzalloc_flex(*parent, canch, icount);
        if (!parent)
                return -ENOMEM;

        parent->channel_cnt = icount;

        init_usb_anchor(&parent->rx_submitted);

        usb_set_intfdata(intf, parent);
        parent->udev = udev;

        /* store the detected endpoints */
        parent->pipe_in = usb_rcvbulkpipe(parent->udev, ep_in->bEndpointAddress);
        parent->pipe_out = usb_sndbulkpipe(parent->udev, ep_out->bEndpointAddress);

        for (i = 0; i < icount; i++) {
                unsigned int hf_size_rx = 0;

                parent->canch[i] = gs_make_candev(i, intf, &dconf);
                if (IS_ERR_OR_NULL(parent->canch[i])) {
                        /* save error code to return later */
                        rc = PTR_ERR(parent->canch[i]);

                        /* on failure destroy previously created candevs */
                        icount = i;
                        for (i = 0; i < icount; i++)
                                gs_destroy_candev(parent->canch[i]);

                        usb_kill_anchored_urbs(&parent->rx_submitted);
                        kfree(parent);
                        return rc;
                }
                parent->canch[i]->parent = parent;

                /* set RX packet size based on FD and if hardware
                 * timestamps are supported.
                 */
                if (parent->canch[i]->can.ctrlmode_supported & CAN_CTRLMODE_FD) {
                        if (parent->canch[i]->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
                                hf_size_rx = struct_size(hf, canfd_ts, 1);
                        else
                                hf_size_rx = struct_size(hf, canfd, 1);
                } else {
                        if (parent->canch[i]->feature & GS_CAN_FEATURE_HW_TIMESTAMP)
                                hf_size_rx = struct_size(hf, classic_can_ts, 1);
                        else
                                hf_size_rx = struct_size(hf, classic_can, 1);
                }
                parent->hf_size_rx = max(parent->hf_size_rx, hf_size_rx);
        }

        return 0;
}

static void gs_usb_disconnect(struct usb_interface *intf)
{
        struct gs_usb *parent = usb_get_intfdata(intf);
        unsigned int i;

        usb_set_intfdata(intf, NULL);

        if (!parent) {
                dev_err(&intf->dev, "Disconnect (nodata)\n");
                return;
        }

        for (i = 0; i < parent->channel_cnt; i++)
                if (parent->canch[i])
                        gs_destroy_candev(parent->canch[i]);

        kfree(parent);
}

static const struct usb_device_id gs_usb_table[] = {
        { USB_DEVICE_INTERFACE_NUMBER(USB_GS_USB_1_VENDOR_ID,
                                      USB_GS_USB_1_PRODUCT_ID, 0) },
        { USB_DEVICE_INTERFACE_NUMBER(USB_CANDLELIGHT_VENDOR_ID,
                                      USB_CANDLELIGHT_PRODUCT_ID, 0) },
        { USB_DEVICE_INTERFACE_NUMBER(USB_CES_CANEXT_FD_VENDOR_ID,
                                      USB_CES_CANEXT_FD_PRODUCT_ID, 0) },
        { USB_DEVICE_INTERFACE_NUMBER(USB_ABE_CANDEBUGGER_FD_VENDOR_ID,
                                      USB_ABE_CANDEBUGGER_FD_PRODUCT_ID, 0) },
        { USB_DEVICE_INTERFACE_NUMBER(USB_XYLANTA_SAINT3_VENDOR_ID,
                                      USB_XYLANTA_SAINT3_PRODUCT_ID, 0) },
        { USB_DEVICE_INTERFACE_NUMBER(USB_CANNECTIVITY_VENDOR_ID,
                                      USB_CANNECTIVITY_PRODUCT_ID, 0) },
        {} /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, gs_usb_table);

static struct usb_driver gs_usb_driver = {
        .name = KBUILD_MODNAME,
        .probe = gs_usb_probe,
        .disconnect = gs_usb_disconnect,
        .id_table = gs_usb_table,
};

module_usb_driver(gs_usb_driver);

MODULE_AUTHOR("Maximilian Schneider <mws@schneidersoft.net>");
MODULE_DESCRIPTION(
"Socket CAN device driver for Geschwister Schneider Technologie-, "
"Entwicklungs- und Vertriebs UG. USB2.0 to CAN interfaces\n"
"and bytewerk.org candleLight USB CAN interfaces.");
MODULE_LICENSE("GPL v2");