can: dev: can-calc-bit-timing(): better sample point calculation

[mirror_ubuntu-artful-kernel.git] / drivers / net / can / dev.c

/*
 * Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
 * Copyright (C) 2006 Andrey Volkov, Varma Electronics
 * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the version 2 of the GNU General Public License
 * as published by the Free Software Foundation
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/skb.h>
#include <linux/can/netlink.h>
#include <linux/can/led.h>
#include <net/rtnetlink.h>

#define MOD_DESC "CAN device driver interface"

MODULE_DESCRIPTION(MOD_DESC);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");

/* CAN DLC to real data length conversion helpers */

static const u8 dlc2len[] = {0, 1, 2, 3, 4, 5, 6, 7,
                             8, 12, 16, 20, 24, 32, 48, 64};

/* get data length from can_dlc with sanitized can_dlc */
u8 can_dlc2len(u8 can_dlc)
{
        return dlc2len[can_dlc & 0x0F];
}
EXPORT_SYMBOL_GPL(can_dlc2len);

static const u8 len2dlc[] = {0, 1, 2, 3, 4, 5, 6, 7, 8,         /* 0 - 8 */
                             9, 9, 9, 9,                        /* 9 - 12 */
                             10, 10, 10, 10,                    /* 13 - 16 */
                             11, 11, 11, 11,                    /* 17 - 20 */
                             12, 12, 12, 12,                    /* 21 - 24 */
                             13, 13, 13, 13, 13, 13, 13, 13,    /* 25 - 32 */
                             14, 14, 14, 14, 14, 14, 14, 14,    /* 33 - 40 */
                             14, 14, 14, 14, 14, 14, 14, 14,    /* 41 - 48 */
                             15, 15, 15, 15, 15, 15, 15, 15,    /* 49 - 56 */
                             15, 15, 15, 15, 15, 15, 15, 15};   /* 57 - 64 */

/* map the sanitized data length to an appropriate data length code */
u8 can_len2dlc(u8 len)
{
        if (unlikely(len > 64))
                return 0xF;

        return len2dlc[len];
}
EXPORT_SYMBOL_GPL(can_len2dlc);

#ifdef CONFIG_CAN_CALC_BITTIMING
#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
#define CAN_CALC_SYNC_SEG 1

/*
 * Bit-timing calculation derived from:
 *
 * Code based on LinCAN sources and H8S2638 project
 * Copyright 2004-2006 Pavel Pisa - DCE FELK CVUT cz
 * Copyright 2005      Stanislav Marek
 * email: pisa@cmp.felk.cvut.cz
 *
 * Calculates proper bit-timing parameters for a specified bit-rate
 * and sample-point, which can then be used to set the bit-timing
 * registers of the CAN controller. You can find more information
 * in the header file linux/can/netlink.h.
 */
static int can_update_sample_point(const struct can_bittiming_const *btc,
                          unsigned int sample_point_nominal, unsigned int tseg,
                          unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,
                          unsigned int *sample_point_error_ptr)
{
        unsigned int sample_point_error, best_sample_point_error = UINT_MAX;
        unsigned int sample_point, best_sample_point = 0;
        unsigned int tseg1, tseg2;
        int i;

        for (i = 0; i <= 1; i++) {
                tseg2 = tseg + CAN_CALC_SYNC_SEG - (sample_point_nominal * (tseg + CAN_CALC_SYNC_SEG)) / 1000 - i;
                tseg2 = clamp(tseg2, btc->tseg2_min, btc->tseg2_max);
                tseg1 = tseg - tseg2;
                if (tseg1 > btc->tseg1_max) {
                        tseg1 = btc->tseg1_max;
                        tseg2 = tseg - tseg1;
                }

                sample_point = 1000 * (tseg + CAN_CALC_SYNC_SEG - tseg2) / (tseg + CAN_CALC_SYNC_SEG);
                sample_point_error = abs(sample_point_nominal - sample_point);

                if ((sample_point <= sample_point_nominal) && (sample_point_error < best_sample_point_error)) {
                        best_sample_point = sample_point;
                        best_sample_point_error = sample_point_error;
                        *tseg1_ptr = tseg1;
                        *tseg2_ptr = tseg2;
                }
        }

        if (sample_point_error_ptr)
                *sample_point_error_ptr = best_sample_point_error;

        return best_sample_point;
}

static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
                              const struct can_bittiming_const *btc)
{
        struct can_priv *priv = netdev_priv(dev);
        unsigned int bitrate;                   /* current bitrate */
        unsigned int bitrate_error;             /* difference between current and nominal value */
        unsigned int best_bitrate_error = UINT_MAX;
        unsigned int sample_point_error;        /* difference between current and nominal value */
        unsigned int best_sample_point_error = UINT_MAX;
        unsigned int sample_point_nominal;      /* nominal sample point */
        unsigned int best_tseg = 0;             /* current best value for tseg */
        unsigned int best_brp = 0;              /* current best value for brp */
        unsigned int brp, tsegall, tseg, tseg1 = 0, tseg2 = 0;
        u64 v64;

        /* Use CiA recommended sample points */
        if (bt->sample_point) {
                sample_point_nominal = bt->sample_point;
        } else {
                if (bt->bitrate > 800000)
                        sample_point_nominal = 750;
                else if (bt->bitrate > 500000)
                        sample_point_nominal = 800;
                else
                        sample_point_nominal = 875;
        }

        /* tseg even = round down, odd = round up */
        for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1;
             tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {
                tsegall = CAN_CALC_SYNC_SEG + tseg / 2;

                /* Compute all possible tseg choices (tseg=tseg1+tseg2) */
                brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;

                /* choose brp step which is possible in system */
                brp = (brp / btc->brp_inc) * btc->brp_inc;
                if ((brp < btc->brp_min) || (brp > btc->brp_max))
                        continue;

                bitrate = priv->clock.freq / (brp * tsegall);
                bitrate_error = abs(bt->bitrate - bitrate);

                /* tseg brp biterror */
                if (bitrate_error > best_bitrate_error)
                        continue;

                /* reset sample point error if we have a better bitrate */
                if (bitrate_error < best_bitrate_error)
                        best_sample_point_error = UINT_MAX;

                can_update_sample_point(btc, sample_point_nominal, tseg / 2, &tseg1, &tseg2, &sample_point_error);
                if (sample_point_error > best_sample_point_error)
                        continue;

                best_sample_point_error = sample_point_error;
                best_bitrate_error = bitrate_error;
                best_tseg = tseg / 2;
                best_brp = brp;

                if (bitrate_error == 0 && sample_point_error == 0)
                        break;
        }

        if (best_bitrate_error) {
                /* Error in one-tenth of a percent */
                v64 = (u64)best_bitrate_error * 1000;
                do_div(v64, bt->bitrate);
                bitrate_error = (u32)v64;
                if (bitrate_error > CAN_CALC_MAX_ERROR) {
                        netdev_err(dev,
                                   "bitrate error %d.%d%% too high\n",
                                   bitrate_error / 10, bitrate_error % 10);
                        return -EDOM;
                }
                netdev_warn(dev, "bitrate error %d.%d%%\n",
                            bitrate_error / 10, bitrate_error % 10);
        }

        /* real sample point */
        bt->sample_point = can_update_sample_point(btc, sample_point_nominal, best_tseg,
                                          &tseg1, &tseg2, NULL);

        v64 = (u64)best_brp * 1000 * 1000 * 1000;
        do_div(v64, priv->clock.freq);
        bt->tq = (u32)v64;
        bt->prop_seg = tseg1 / 2;
        bt->phase_seg1 = tseg1 - bt->prop_seg;
        bt->phase_seg2 = tseg2;

        /* check for sjw user settings */
        if (!bt->sjw || !btc->sjw_max) {
                bt->sjw = 1;
        } else {
                /* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */
                if (bt->sjw > btc->sjw_max)
                        bt->sjw = btc->sjw_max;
                /* bt->sjw must not be higher than tseg2 */
                if (tseg2 < bt->sjw)
                        bt->sjw = tseg2;
        }

        bt->brp = best_brp;

        /* real bitrate */
        bt->bitrate = priv->clock.freq / (bt->brp * (CAN_CALC_SYNC_SEG + tseg1 + tseg2));

        return 0;
}
#else /* !CONFIG_CAN_CALC_BITTIMING */
static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
                              const struct can_bittiming_const *btc)
{
        netdev_err(dev, "bit-timing calculation not available\n");
        return -EINVAL;
}
#endif /* CONFIG_CAN_CALC_BITTIMING */

/*
 * Checks the validity of the specified bit-timing parameters prop_seg,
 * phase_seg1, phase_seg2 and sjw and tries to determine the bitrate
 * prescaler value brp. You can find more information in the header
 * file linux/can/netlink.h.
 */
static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt,
                               const struct can_bittiming_const *btc)
{
        struct can_priv *priv = netdev_priv(dev);
        int tseg1, alltseg;
        u64 brp64;

        tseg1 = bt->prop_seg + bt->phase_seg1;
        if (!bt->sjw)
                bt->sjw = 1;
        if (bt->sjw > btc->sjw_max ||
            tseg1 < btc->tseg1_min || tseg1 > btc->tseg1_max ||
            bt->phase_seg2 < btc->tseg2_min || bt->phase_seg2 > btc->tseg2_max)
                return -ERANGE;

        brp64 = (u64)priv->clock.freq * (u64)bt->tq;
        if (btc->brp_inc > 1)
                do_div(brp64, btc->brp_inc);
        brp64 += 500000000UL - 1;
        do_div(brp64, 1000000000UL); /* the practicable BRP */
        if (btc->brp_inc > 1)
                brp64 *= btc->brp_inc;
        bt->brp = (u32)brp64;

        if (bt->brp < btc->brp_min || bt->brp > btc->brp_max)
                return -EINVAL;

        alltseg = bt->prop_seg + bt->phase_seg1 + bt->phase_seg2 + 1;
        bt->bitrate = priv->clock.freq / (bt->brp * alltseg);
        bt->sample_point = ((tseg1 + 1) * 1000) / alltseg;

        return 0;
}

static int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,
                             const struct can_bittiming_const *btc)
{
        int err;

        /* Check if the CAN device has bit-timing parameters */
        if (!btc)
                return -EOPNOTSUPP;

        /*
         * Depending on the given can_bittiming parameter structure the CAN
         * timing parameters are calculated based on the provided bitrate OR
         * alternatively the CAN timing parameters (tq, prop_seg, etc.) are
         * provided directly which are then checked and fixed up.
         */
        if (!bt->tq && bt->bitrate)
                err = can_calc_bittiming(dev, bt, btc);
        else if (bt->tq && !bt->bitrate)
                err = can_fixup_bittiming(dev, bt, btc);
        else
                err = -EINVAL;

        return err;
}

static void can_update_state_error_stats(struct net_device *dev,
                                         enum can_state new_state)
{
        struct can_priv *priv = netdev_priv(dev);

        if (new_state <= priv->state)
                return;

        switch (new_state) {
        case CAN_STATE_ERROR_WARNING:
                priv->can_stats.error_warning++;
                break;
        case CAN_STATE_ERROR_PASSIVE:
                priv->can_stats.error_passive++;
                break;
        case CAN_STATE_BUS_OFF:
                priv->can_stats.bus_off++;
                break;
        default:
                break;
        }
}

static int can_tx_state_to_frame(struct net_device *dev, enum can_state state)
{
        switch (state) {
        case CAN_STATE_ERROR_ACTIVE:
                return CAN_ERR_CRTL_ACTIVE;
        case CAN_STATE_ERROR_WARNING:
                return CAN_ERR_CRTL_TX_WARNING;
        case CAN_STATE_ERROR_PASSIVE:
                return CAN_ERR_CRTL_TX_PASSIVE;
        default:
                return 0;
        }
}

static int can_rx_state_to_frame(struct net_device *dev, enum can_state state)
{
        switch (state) {
        case CAN_STATE_ERROR_ACTIVE:
                return CAN_ERR_CRTL_ACTIVE;
        case CAN_STATE_ERROR_WARNING:
                return CAN_ERR_CRTL_RX_WARNING;
        case CAN_STATE_ERROR_PASSIVE:
                return CAN_ERR_CRTL_RX_PASSIVE;
        default:
                return 0;
        }
}

void can_change_state(struct net_device *dev, struct can_frame *cf,
                      enum can_state tx_state, enum can_state rx_state)
{
        struct can_priv *priv = netdev_priv(dev);
        enum can_state new_state = max(tx_state, rx_state);

        if (unlikely(new_state == priv->state)) {
                netdev_warn(dev, "%s: oops, state did not change", __func__);
                return;
        }

        netdev_dbg(dev, "New error state: %d\n", new_state);

        can_update_state_error_stats(dev, new_state);
        priv->state = new_state;

        if (unlikely(new_state == CAN_STATE_BUS_OFF)) {
                cf->can_id |= CAN_ERR_BUSOFF;
                return;
        }

        cf->can_id |= CAN_ERR_CRTL;
        cf->data[1] |= tx_state >= rx_state ?
                       can_tx_state_to_frame(dev, tx_state) : 0;
        cf->data[1] |= tx_state <= rx_state ?
                       can_rx_state_to_frame(dev, rx_state) : 0;
}
EXPORT_SYMBOL_GPL(can_change_state);

/*
 * Local echo of CAN messages
 *
 * CAN network devices *should* support a local echo functionality
 * (see Documentation/networking/can.txt). To test the handling of CAN
 * interfaces that do not support the local echo both driver types are
 * implemented. In the case that the driver does not support the echo
 * the IFF_ECHO remains clear in dev->flags. This causes the PF_CAN core
 * to perform the echo as a fallback solution.
 */
static void can_flush_echo_skb(struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        int i;

        for (i = 0; i < priv->echo_skb_max; i++) {
                if (priv->echo_skb[i]) {
                        kfree_skb(priv->echo_skb[i]);
                        priv->echo_skb[i] = NULL;
                        stats->tx_dropped++;
                        stats->tx_aborted_errors++;
                }
        }
}

/*
 * Put the skb on the stack to be looped backed locally lateron
 *
 * The function is typically called in the start_xmit function
 * of the device driver. The driver must protect access to
 * priv->echo_skb, if necessary.
 */
void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
                      unsigned int idx)
{
        struct can_priv *priv = netdev_priv(dev);

        BUG_ON(idx >= priv->echo_skb_max);

        /* check flag whether this packet has to be looped back */
        if (!(dev->flags & IFF_ECHO) || skb->pkt_type != PACKET_LOOPBACK ||
            (skb->protocol != htons(ETH_P_CAN) &&
             skb->protocol != htons(ETH_P_CANFD))) {
                kfree_skb(skb);
                return;
        }

        if (!priv->echo_skb[idx]) {

                skb = can_create_echo_skb(skb);
                if (!skb)
                        return;

                /* make settings for echo to reduce code in irq context */
                skb->pkt_type = PACKET_BROADCAST;
                skb->ip_summed = CHECKSUM_UNNECESSARY;
                skb->dev = dev;

                /* save this skb for tx interrupt echo handling */
                priv->echo_skb[idx] = skb;
        } else {
                /* locking problem with netif_stop_queue() ?? */
                netdev_err(dev, "%s: BUG! echo_skb is occupied!\n", __func__);
                kfree_skb(skb);
        }
}
EXPORT_SYMBOL_GPL(can_put_echo_skb);

/*
 * Get the skb from the stack and loop it back locally
 *
 * The function is typically called when the TX done interrupt
 * is handled in the device driver. The driver must protect
 * access to priv->echo_skb, if necessary.
 */
unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx)
{
        struct can_priv *priv = netdev_priv(dev);

        BUG_ON(idx >= priv->echo_skb_max);

        if (priv->echo_skb[idx]) {
                struct sk_buff *skb = priv->echo_skb[idx];
                struct can_frame *cf = (struct can_frame *)skb->data;
                u8 dlc = cf->can_dlc;

                netif_rx(priv->echo_skb[idx]);
                priv->echo_skb[idx] = NULL;

                return dlc;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(can_get_echo_skb);

/*
  * Remove the skb from the stack and free it.
  *
  * The function is typically called when TX failed.
  */
void can_free_echo_skb(struct net_device *dev, unsigned int idx)
{
        struct can_priv *priv = netdev_priv(dev);

        BUG_ON(idx >= priv->echo_skb_max);

        if (priv->echo_skb[idx]) {
                dev_kfree_skb_any(priv->echo_skb[idx]);
                priv->echo_skb[idx] = NULL;
        }
}
EXPORT_SYMBOL_GPL(can_free_echo_skb);

/*
 * CAN device restart for bus-off recovery
 */
static void can_restart(unsigned long data)
{
        struct net_device *dev = (struct net_device *)data;
        struct can_priv *priv = netdev_priv(dev);
        struct net_device_stats *stats = &dev->stats;
        struct sk_buff *skb;
        struct can_frame *cf;
        int err;

        BUG_ON(netif_carrier_ok(dev));

        /*
         * No synchronization needed because the device is bus-off and
         * no messages can come in or go out.
         */
        can_flush_echo_skb(dev);

        /* send restart message upstream */
        skb = alloc_can_err_skb(dev, &cf);
        if (skb == NULL) {
                err = -ENOMEM;
                goto restart;
        }
        cf->can_id |= CAN_ERR_RESTARTED;

        netif_rx(skb);

        stats->rx_packets++;
        stats->rx_bytes += cf->can_dlc;

restart:
        netdev_dbg(dev, "restarted\n");
        priv->can_stats.restarts++;

        /* Now restart the device */
        err = priv->do_set_mode(dev, CAN_MODE_START);

        netif_carrier_on(dev);
        if (err)
                netdev_err(dev, "Error %d during restart", err);
}

int can_restart_now(struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);

        /*
         * A manual restart is only permitted if automatic restart is
         * disabled and the device is in the bus-off state
         */
        if (priv->restart_ms)
                return -EINVAL;
        if (priv->state != CAN_STATE_BUS_OFF)
                return -EBUSY;

        /* Runs as soon as possible in the timer context */
        mod_timer(&priv->restart_timer, jiffies);

        return 0;
}

/*
 * CAN bus-off
 *
 * This functions should be called when the device goes bus-off to
 * tell the netif layer that no more packets can be sent or received.
 * If enabled, a timer is started to trigger bus-off recovery.
 */
void can_bus_off(struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);

        netdev_dbg(dev, "bus-off\n");

        netif_carrier_off(dev);

        if (priv->restart_ms)
                mod_timer(&priv->restart_timer,
                          jiffies + (priv->restart_ms * HZ) / 1000);
}
EXPORT_SYMBOL_GPL(can_bus_off);

static void can_setup(struct net_device *dev)
{
        dev->type = ARPHRD_CAN;
        dev->mtu = CAN_MTU;
        dev->hard_header_len = 0;
        dev->addr_len = 0;
        dev->tx_queue_len = 10;

        /* New-style flags. */
        dev->flags = IFF_NOARP;
        dev->features = NETIF_F_HW_CSUM;
}

struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)
{
        struct sk_buff *skb;

        skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
                               sizeof(struct can_frame));
        if (unlikely(!skb))
                return NULL;

        skb->protocol = htons(ETH_P_CAN);
        skb->pkt_type = PACKET_BROADCAST;
        skb->ip_summed = CHECKSUM_UNNECESSARY;

        skb_reset_mac_header(skb);
        skb_reset_network_header(skb);
        skb_reset_transport_header(skb);

        can_skb_reserve(skb);
        can_skb_prv(skb)->ifindex = dev->ifindex;
        can_skb_prv(skb)->skbcnt = 0;

        *cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
        memset(*cf, 0, sizeof(struct can_frame));

        return skb;
}
EXPORT_SYMBOL_GPL(alloc_can_skb);

struct sk_buff *alloc_canfd_skb(struct net_device *dev,
                                struct canfd_frame **cfd)
{
        struct sk_buff *skb;

        skb = netdev_alloc_skb(dev, sizeof(struct can_skb_priv) +
                               sizeof(struct canfd_frame));
        if (unlikely(!skb))
                return NULL;

        skb->protocol = htons(ETH_P_CANFD);
        skb->pkt_type = PACKET_BROADCAST;
        skb->ip_summed = CHECKSUM_UNNECESSARY;

        skb_reset_mac_header(skb);
        skb_reset_network_header(skb);
        skb_reset_transport_header(skb);

        can_skb_reserve(skb);
        can_skb_prv(skb)->ifindex = dev->ifindex;
        can_skb_prv(skb)->skbcnt = 0;

        *cfd = (struct canfd_frame *)skb_put(skb, sizeof(struct canfd_frame));
        memset(*cfd, 0, sizeof(struct canfd_frame));

        return skb;
}
EXPORT_SYMBOL_GPL(alloc_canfd_skb);

struct sk_buff *alloc_can_err_skb(struct net_device *dev, struct can_frame **cf)
{
        struct sk_buff *skb;

        skb = alloc_can_skb(dev, cf);
        if (unlikely(!skb))
                return NULL;

        (*cf)->can_id = CAN_ERR_FLAG;
        (*cf)->can_dlc = CAN_ERR_DLC;

        return skb;
}
EXPORT_SYMBOL_GPL(alloc_can_err_skb);

/*
 * Allocate and setup space for the CAN network device
 */
struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max)
{
        struct net_device *dev;
        struct can_priv *priv;
        int size;

        if (echo_skb_max)
                size = ALIGN(sizeof_priv, sizeof(struct sk_buff *)) +
                        echo_skb_max * sizeof(struct sk_buff *);
        else
                size = sizeof_priv;

        dev = alloc_netdev(size, "can%d", NET_NAME_UNKNOWN, can_setup);
        if (!dev)
                return NULL;

        priv = netdev_priv(dev);

        if (echo_skb_max) {
                priv->echo_skb_max = echo_skb_max;
                priv->echo_skb = (void *)priv +
                        ALIGN(sizeof_priv, sizeof(struct sk_buff *));
        }

        priv->state = CAN_STATE_STOPPED;

        init_timer(&priv->restart_timer);

        return dev;
}
EXPORT_SYMBOL_GPL(alloc_candev);

/*
 * Free space of the CAN network device
 */
void free_candev(struct net_device *dev)
{
        free_netdev(dev);
}
EXPORT_SYMBOL_GPL(free_candev);

/*
 * changing MTU and control mode for CAN/CANFD devices
 */
int can_change_mtu(struct net_device *dev, int new_mtu)
{
        struct can_priv *priv = netdev_priv(dev);

        /* Do not allow changing the MTU while running */
        if (dev->flags & IFF_UP)
                return -EBUSY;

        /* allow change of MTU according to the CANFD ability of the device */
        switch (new_mtu) {
        case CAN_MTU:
                /* 'CANFD-only' controllers can not switch to CAN_MTU */
                if (priv->ctrlmode_static & CAN_CTRLMODE_FD)
                        return -EINVAL;

                priv->ctrlmode &= ~CAN_CTRLMODE_FD;
                break;

        case CANFD_MTU:
                /* check for potential CANFD ability */
                if (!(priv->ctrlmode_supported & CAN_CTRLMODE_FD) &&
                    !(priv->ctrlmode_static & CAN_CTRLMODE_FD))
                        return -EINVAL;

                priv->ctrlmode |= CAN_CTRLMODE_FD;
                break;

        default:
                return -EINVAL;
        }

        dev->mtu = new_mtu;
        return 0;
}
EXPORT_SYMBOL_GPL(can_change_mtu);

/*
 * Common open function when the device gets opened.
 *
 * This function should be called in the open function of the device
 * driver.
 */
int open_candev(struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);

        if (!priv->bittiming.bitrate) {
                netdev_err(dev, "bit-timing not yet defined\n");
                return -EINVAL;
        }

        /* For CAN FD the data bitrate has to be >= the arbitration bitrate */
        if ((priv->ctrlmode & CAN_CTRLMODE_FD) &&
            (!priv->data_bittiming.bitrate ||
             (priv->data_bittiming.bitrate < priv->bittiming.bitrate))) {
                netdev_err(dev, "incorrect/missing data bit-timing\n");
                return -EINVAL;
        }

        /* Switch carrier on if device was stopped while in bus-off state */
        if (!netif_carrier_ok(dev))
                netif_carrier_on(dev);

        setup_timer(&priv->restart_timer, can_restart, (unsigned long)dev);

        return 0;
}
EXPORT_SYMBOL_GPL(open_candev);

/*
 * Common close function for cleanup before the device gets closed.
 *
 * This function should be called in the close function of the device
 * driver.
 */
void close_candev(struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);

        del_timer_sync(&priv->restart_timer);
        can_flush_echo_skb(dev);
}
EXPORT_SYMBOL_GPL(close_candev);

/*
 * CAN netlink interface
 */
static const struct nla_policy can_policy[IFLA_CAN_MAX + 1] = {
        [IFLA_CAN_STATE]        = { .type = NLA_U32 },
        [IFLA_CAN_CTRLMODE]     = { .len = sizeof(struct can_ctrlmode) },
        [IFLA_CAN_RESTART_MS]   = { .type = NLA_U32 },
        [IFLA_CAN_RESTART]      = { .type = NLA_U32 },
        [IFLA_CAN_BITTIMING]    = { .len = sizeof(struct can_bittiming) },
        [IFLA_CAN_BITTIMING_CONST]
                                = { .len = sizeof(struct can_bittiming_const) },
        [IFLA_CAN_CLOCK]        = { .len = sizeof(struct can_clock) },
        [IFLA_CAN_BERR_COUNTER] = { .len = sizeof(struct can_berr_counter) },
        [IFLA_CAN_DATA_BITTIMING]
                                = { .len = sizeof(struct can_bittiming) },
        [IFLA_CAN_DATA_BITTIMING_CONST]
                                = { .len = sizeof(struct can_bittiming_const) },
};

static int can_validate(struct nlattr *tb[], struct nlattr *data[])
{
        bool is_can_fd = false;

        /* Make sure that valid CAN FD configurations always consist of
         * - nominal/arbitration bittiming
         * - data bittiming
         * - control mode with CAN_CTRLMODE_FD set
         */

        if (data[IFLA_CAN_CTRLMODE]) {
                struct can_ctrlmode *cm = nla_data(data[IFLA_CAN_CTRLMODE]);

                is_can_fd = cm->flags & cm->mask & CAN_CTRLMODE_FD;
        }

        if (is_can_fd) {
                if (!data[IFLA_CAN_BITTIMING] || !data[IFLA_CAN_DATA_BITTIMING])
                        return -EOPNOTSUPP;
        }

        if (data[IFLA_CAN_DATA_BITTIMING]) {
                if (!is_can_fd || !data[IFLA_CAN_BITTIMING])
                        return -EOPNOTSUPP;
        }

        return 0;
}

static int can_changelink(struct net_device *dev,
                          struct nlattr *tb[], struct nlattr *data[])
{
        struct can_priv *priv = netdev_priv(dev);
        int err;

        /* We need synchronization with dev->stop() */
        ASSERT_RTNL();

        if (data[IFLA_CAN_BITTIMING]) {
                struct can_bittiming bt;

                /* Do not allow changing bittiming while running */
                if (dev->flags & IFF_UP)
                        return -EBUSY;
                memcpy(&bt, nla_data(data[IFLA_CAN_BITTIMING]), sizeof(bt));
                err = can_get_bittiming(dev, &bt, priv->bittiming_const);
                if (err)
                        return err;
                memcpy(&priv->bittiming, &bt, sizeof(bt));

                if (priv->do_set_bittiming) {
                        /* Finally, set the bit-timing registers */
                        err = priv->do_set_bittiming(dev);
                        if (err)
                                return err;
                }
        }

        if (data[IFLA_CAN_CTRLMODE]) {
                struct can_ctrlmode *cm;
                u32 ctrlstatic;
                u32 maskedflags;

                /* Do not allow changing controller mode while running */
                if (dev->flags & IFF_UP)
                        return -EBUSY;
                cm = nla_data(data[IFLA_CAN_CTRLMODE]);
                ctrlstatic = priv->ctrlmode_static;
                maskedflags = cm->flags & cm->mask;

                /* check whether provided bits are allowed to be passed */
                if (cm->mask & ~(priv->ctrlmode_supported | ctrlstatic))
                        return -EOPNOTSUPP;

                /* do not check for static fd-non-iso if 'fd' is disabled */
                if (!(maskedflags & CAN_CTRLMODE_FD))
                        ctrlstatic &= ~CAN_CTRLMODE_FD_NON_ISO;

                /* make sure static options are provided by configuration */
                if ((maskedflags & ctrlstatic) != ctrlstatic)
                        return -EOPNOTSUPP;

                /* clear bits to be modified and copy the flag values */
                priv->ctrlmode &= ~cm->mask;
                priv->ctrlmode |= maskedflags;

                /* CAN_CTRLMODE_FD can only be set when driver supports FD */
                if (priv->ctrlmode & CAN_CTRLMODE_FD)
                        dev->mtu = CANFD_MTU;
                else
                        dev->mtu = CAN_MTU;
        }

        if (data[IFLA_CAN_RESTART_MS]) {
                /* Do not allow changing restart delay while running */
                if (dev->flags & IFF_UP)
                        return -EBUSY;
                priv->restart_ms = nla_get_u32(data[IFLA_CAN_RESTART_MS]);
        }

        if (data[IFLA_CAN_RESTART]) {
                /* Do not allow a restart while not running */
                if (!(dev->flags & IFF_UP))
                        return -EINVAL;
                err = can_restart_now(dev);
                if (err)
                        return err;
        }

        if (data[IFLA_CAN_DATA_BITTIMING]) {
                struct can_bittiming dbt;

                /* Do not allow changing bittiming while running */
                if (dev->flags & IFF_UP)
                        return -EBUSY;
                memcpy(&dbt, nla_data(data[IFLA_CAN_DATA_BITTIMING]),
                       sizeof(dbt));
                err = can_get_bittiming(dev, &dbt, priv->data_bittiming_const);
                if (err)
                        return err;
                memcpy(&priv->data_bittiming, &dbt, sizeof(dbt));

                if (priv->do_set_data_bittiming) {
                        /* Finally, set the bit-timing registers */
                        err = priv->do_set_data_bittiming(dev);
                        if (err)
                                return err;
                }
        }

        return 0;
}

static size_t can_get_size(const struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);
        size_t size = 0;

        if (priv->bittiming.bitrate)                            /* IFLA_CAN_BITTIMING */
                size += nla_total_size(sizeof(struct can_bittiming));
        if (priv->bittiming_const)                              /* IFLA_CAN_BITTIMING_CONST */
                size += nla_total_size(sizeof(struct can_bittiming_const));
        size += nla_total_size(sizeof(struct can_clock));       /* IFLA_CAN_CLOCK */
        size += nla_total_size(sizeof(u32));                    /* IFLA_CAN_STATE */
        size += nla_total_size(sizeof(struct can_ctrlmode));    /* IFLA_CAN_CTRLMODE */
        size += nla_total_size(sizeof(u32));                    /* IFLA_CAN_RESTART_MS */
        if (priv->do_get_berr_counter)                          /* IFLA_CAN_BERR_COUNTER */
                size += nla_total_size(sizeof(struct can_berr_counter));
        if (priv->data_bittiming.bitrate)                       /* IFLA_CAN_DATA_BITTIMING */
                size += nla_total_size(sizeof(struct can_bittiming));
        if (priv->data_bittiming_const)                         /* IFLA_CAN_DATA_BITTIMING_CONST */
                size += nla_total_size(sizeof(struct can_bittiming_const));

        return size;
}

static int can_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);
        struct can_ctrlmode cm = {.flags = priv->ctrlmode};
        struct can_berr_counter bec;
        enum can_state state = priv->state;

        if (priv->do_get_state)
                priv->do_get_state(dev, &state);

        if ((priv->bittiming.bitrate &&
             nla_put(skb, IFLA_CAN_BITTIMING,
                     sizeof(priv->bittiming), &priv->bittiming)) ||

            (priv->bittiming_const &&
             nla_put(skb, IFLA_CAN_BITTIMING_CONST,
                     sizeof(*priv->bittiming_const), priv->bittiming_const)) ||

            nla_put(skb, IFLA_CAN_CLOCK, sizeof(priv->clock), &priv->clock) ||
            nla_put_u32(skb, IFLA_CAN_STATE, state) ||
            nla_put(skb, IFLA_CAN_CTRLMODE, sizeof(cm), &cm) ||
            nla_put_u32(skb, IFLA_CAN_RESTART_MS, priv->restart_ms) ||

            (priv->do_get_berr_counter &&
             !priv->do_get_berr_counter(dev, &bec) &&
             nla_put(skb, IFLA_CAN_BERR_COUNTER, sizeof(bec), &bec)) ||

            (priv->data_bittiming.bitrate &&
             nla_put(skb, IFLA_CAN_DATA_BITTIMING,
                     sizeof(priv->data_bittiming), &priv->data_bittiming)) ||

            (priv->data_bittiming_const &&
             nla_put(skb, IFLA_CAN_DATA_BITTIMING_CONST,
                     sizeof(*priv->data_bittiming_const),
                     priv->data_bittiming_const)))
                return -EMSGSIZE;

        return 0;
}

static size_t can_get_xstats_size(const struct net_device *dev)
{
        return sizeof(struct can_device_stats);
}

static int can_fill_xstats(struct sk_buff *skb, const struct net_device *dev)
{
        struct can_priv *priv = netdev_priv(dev);

        if (nla_put(skb, IFLA_INFO_XSTATS,
                    sizeof(priv->can_stats), &priv->can_stats))
                goto nla_put_failure;
        return 0;

nla_put_failure:
        return -EMSGSIZE;
}

static int can_newlink(struct net *src_net, struct net_device *dev,
                       struct nlattr *tb[], struct nlattr *data[])
{
        return -EOPNOTSUPP;
}

static struct rtnl_link_ops can_link_ops __read_mostly = {
        .kind           = "can",
        .maxtype        = IFLA_CAN_MAX,
        .policy         = can_policy,
        .setup          = can_setup,
        .validate       = can_validate,
        .newlink        = can_newlink,
        .changelink     = can_changelink,
        .get_size       = can_get_size,
        .fill_info      = can_fill_info,
        .get_xstats_size = can_get_xstats_size,
        .fill_xstats    = can_fill_xstats,
};

/*
 * Register the CAN network device
 */
int register_candev(struct net_device *dev)
{
        dev->rtnl_link_ops = &can_link_ops;
        return register_netdev(dev);
}
EXPORT_SYMBOL_GPL(register_candev);

/*
 * Unregister the CAN network device
 */
void unregister_candev(struct net_device *dev)
{
        unregister_netdev(dev);
}
EXPORT_SYMBOL_GPL(unregister_candev);

/*
 * Test if a network device is a candev based device
 * and return the can_priv* if so.
 */
struct can_priv *safe_candev_priv(struct net_device *dev)
{
        if ((dev->type != ARPHRD_CAN) || (dev->rtnl_link_ops != &can_link_ops))
                return NULL;

        return netdev_priv(dev);
}
EXPORT_SYMBOL_GPL(safe_candev_priv);

static __init int can_dev_init(void)
{
        int err;

        can_led_notifier_init();

        err = rtnl_link_register(&can_link_ops);
        if (!err)
                printk(KERN_INFO MOD_DESC "\n");

        return err;
}
module_init(can_dev_init);

static __exit void can_dev_exit(void)
{
        rtnl_link_unregister(&can_link_ops);

        can_led_notifier_exit();
}
module_exit(can_dev_exit);

MODULE_ALIAS_RTNL_LINK("can");