diff options
Diffstat (limited to 'drivers/net/can/dev.c')
| -rw-r--r-- | drivers/net/can/dev.c | 657 |
1 files changed, 657 insertions, 0 deletions
diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c new file mode 100644 index 0000000..52b0e7d --- /dev/null +++ b/drivers/net/can/dev.c @@ -0,0 +1,657 @@ +/* + * 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, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/netdevice.h> +#include <linux/if_arp.h> +#include <linux/can.h> +#include <linux/can/dev.h> +#include <linux/can/netlink.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>"); + +#ifdef CONFIG_CAN_CALC_BITTIMING +#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */ + +/* + * 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_spt(const struct can_bittiming_const *btc, + int sampl_pt, int tseg, int *tseg1, int *tseg2) +{ + *tseg2 = tseg + 1 - (sampl_pt * (tseg + 1)) / 1000; + if (*tseg2 < btc->tseg2_min) + *tseg2 = btc->tseg2_min; + if (*tseg2 > btc->tseg2_max) + *tseg2 = btc->tseg2_max; + *tseg1 = tseg - *tseg2; + if (*tseg1 > btc->tseg1_max) { + *tseg1 = btc->tseg1_max; + *tseg2 = tseg - *tseg1; + } + return 1000 * (tseg + 1 - *tseg2) / (tseg + 1); +} + +static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt) +{ + struct can_priv *priv = netdev_priv(dev); + const struct can_bittiming_const *btc = priv->bittiming_const; + long rate, best_rate = 0; + long best_error = 1000000000, error = 0; + int best_tseg = 0, best_brp = 0, brp = 0; + int tsegall, tseg = 0, tseg1 = 0, tseg2 = 0; + int spt_error = 1000, spt = 0, sampl_pt; + u64 v64; + + if (!priv->bittiming_const) + return -ENOTSUPP; + + /* Use CIA recommended sample points */ + if (bt->sample_point) { + sampl_pt = bt->sample_point; + } else { + if (bt->bitrate > 800000) + sampl_pt = 750; + else if (bt->bitrate > 500000) + sampl_pt = 800; + else + sampl_pt = 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 = 1 + tseg / 2; + /* Compute all possible tseg choices (tseg=tseg1+tseg2) */ + brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2; + /* chose 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; + rate = priv->clock.freq / (brp * tsegall); + error = bt->bitrate - rate; + /* tseg brp biterror */ + if (error < 0) + error = -error; + if (error > best_error) + continue; + best_error = error; + if (error == 0) { + spt = can_update_spt(btc, sampl_pt, tseg / 2, + &tseg1, &tseg2); + error = sampl_pt - spt; + if (error < 0) + error = -error; + if (error > spt_error) + continue; + spt_error = error; + } + best_tseg = tseg / 2; + best_brp = brp; + best_rate = rate; + if (error == 0) + break; + } + + if (best_error) { + /* Error in one-tenth of a percent */ + error = (best_error * 1000) / bt->bitrate; + if (error > CAN_CALC_MAX_ERROR) { + dev_err(dev->dev.parent, + "bitrate error %ld.%ld%% too high\n", + error / 10, error % 10); + return -EDOM; + } else { + dev_warn(dev->dev.parent, "bitrate error %ld.%ld%%\n", + error / 10, error % 10); + } + } + + /* real sample point */ + bt->sample_point = can_update_spt(btc, sampl_pt, best_tseg, + &tseg1, &tseg2); + + v64 = (u64)best_brp * 1000000000UL; + 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; + bt->sjw = 1; + bt->brp = best_brp; + /* real bit-rate */ + bt->bitrate = priv->clock.freq / (bt->brp * (tseg1 + tseg2 + 1)); + + return 0; +} +#else /* !CONFIG_CAN_CALC_BITTIMING */ +static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt) +{ + dev_err(dev->dev.parent, "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) +{ + struct can_priv *priv = netdev_priv(dev); + const struct can_bittiming_const *btc = priv->bittiming_const; + int tseg1, alltseg; + u64 brp64; + + if (!priv->bittiming_const) + return -ENOTSUPP; + + 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; +} + +int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt) +{ + struct can_priv *priv = netdev_priv(dev); + int err; + + /* Check if the CAN device has bit-timing parameters */ + if (priv->bittiming_const) { + + /* Non-expert mode? Check if the bitrate has been pre-defined */ + if (!bt->tq) + /* Determine bit-timing parameters */ + err = can_calc_bittiming(dev, bt); + else + /* Check bit-timing params and calculate proper brp */ + err = can_fixup_bittiming(dev, bt); + if (err) + return err; + } + + return 0; +} + +/* + * 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 < CAN_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, int idx) +{ + struct can_priv *priv = netdev_priv(dev); + + /* check flag whether this packet has to be looped back */ + if (!(dev->flags & IFF_ECHO) || skb->pkt_type != PACKET_LOOPBACK) { + kfree_skb(skb); + return; + } + + if (!priv->echo_skb[idx]) { + struct sock *srcsk = skb->sk; + + if (atomic_read(&skb->users) != 1) { + struct sk_buff *old_skb = skb; + + skb = skb_clone(old_skb, GFP_ATOMIC); + kfree_skb(old_skb); + if (!skb) + return; + } else + skb_orphan(skb); + + skb->sk = srcsk; + + /* make settings for echo to reduce code in irq context */ + skb->protocol = htons(ETH_P_CAN); + 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() ?? */ + dev_err(dev->dev.parent, "%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. + */ +void can_get_echo_skb(struct net_device *dev, int idx) +{ + struct can_priv *priv = netdev_priv(dev); + + if ((dev->flags & IFF_ECHO) && priv->echo_skb[idx]) { + netif_rx(priv->echo_skb[idx]); + priv->echo_skb[idx] = NULL; + } +} +EXPORT_SYMBOL_GPL(can_get_echo_skb); + +/* + * CAN device restart for bus-off recovery + */ +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 = dev_alloc_skb(sizeof(struct can_frame)); + if (skb == NULL) { + err = -ENOMEM; + goto out; + } + skb->dev = dev; + skb->protocol = htons(ETH_P_CAN); + cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame)); + memset(cf, 0, sizeof(struct can_frame)); + cf->can_id = CAN_ERR_FLAG | CAN_ERR_RESTARTED; + cf->can_dlc = CAN_ERR_DLC; + + netif_rx(skb); + + dev->last_rx = jiffies; + stats->rx_packets++; + stats->rx_bytes += cf->can_dlc; + + dev_dbg(dev->dev.parent, "restarted\n"); + priv->can_stats.restarts++; + + /* Now restart the device */ + err = priv->do_set_mode(dev, CAN_MODE_START); + +out: + netif_carrier_on(dev); + if (err) + dev_err(dev->dev.parent, "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); + + dev_dbg(dev->dev.parent, "bus-off\n"); + + netif_carrier_off(dev); + priv->can_stats.bus_off++; + + 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 = sizeof(struct can_frame); + 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_NO_CSUM; +} + +/* + * Allocate and setup space for the CAN network device + */ +struct net_device *alloc_candev(int sizeof_priv) +{ + struct net_device *dev; + struct can_priv *priv; + + dev = alloc_netdev(sizeof_priv, "can%d", can_setup); + if (!dev) + return NULL; + + priv = netdev_priv(dev); + + 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); + +/* + * 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.tq && !priv->bittiming.bitrate) { + dev_err(dev->dev.parent, "bit-timing not yet defined\n"); + return -EINVAL; + } + + setup_timer(&priv->restart_timer, can_restart, (unsigned long)dev); + + return 0; +} +EXPORT_SYMBOL(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); + + if (del_timer_sync(&priv->restart_timer)) + dev_put(dev); + 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) }, +}; + +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_CTRLMODE]) { + struct can_ctrlmode *cm; + + /* Do not allow changing controller mode while running */ + if (dev->flags & IFF_UP) + return -EBUSY; + cm = nla_data(data[IFLA_CAN_CTRLMODE]); + priv->ctrlmode &= ~cm->mask; + priv->ctrlmode |= cm->flags; + } + + 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)); + if ((!bt.bitrate && !bt.tq) || (bt.bitrate && bt.tq)) + return -EINVAL; + err = can_get_bittiming(dev, &bt); + 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_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; + } + + return 0; +} + +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}; + enum can_state state = priv->state; + + if (priv->do_get_state) + priv->do_get_state(dev, &state); + 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); + NLA_PUT(skb, IFLA_CAN_BITTIMING, + sizeof(priv->bittiming), &priv->bittiming); + NLA_PUT(skb, IFLA_CAN_CLOCK, sizeof(cm), &priv->clock); + if (priv->bittiming_const) + NLA_PUT(skb, IFLA_CAN_BITTIMING_CONST, + sizeof(*priv->bittiming_const), priv->bittiming_const); + + return 0; + +nla_put_failure: + return -EMSGSIZE; +} + +static int can_fill_xstats(struct sk_buff *skb, const struct net_device *dev) +{ + struct can_priv *priv = netdev_priv(dev); + + NLA_PUT(skb, IFLA_INFO_XSTATS, + sizeof(priv->can_stats), &priv->can_stats); + + return 0; + +nla_put_failure: + return -EMSGSIZE; +} + +static struct rtnl_link_ops can_link_ops __read_mostly = { + .kind = "can", + .maxtype = IFLA_CAN_MAX, + .policy = can_policy, + .setup = can_setup, + .changelink = can_changelink, + .fill_info = can_fill_info, + .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); + +static __init int can_dev_init(void) +{ + int err; + + 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); +} +module_exit(can_dev_exit); + +MODULE_ALIAS_RTNL_LINK("can"); |