/*
* 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 restart;
}
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;
restart:
dev_dbg(dev->dev.parent, "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)
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;
}
/* 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);
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");
