can: CAN Network device driver and Netlink interface

	  This driver can also be built as a module.  If so, the module

	  will be called vcan.

config CAN_DEV

	tristate "Platform CAN drivers with Netlink support"

	depends on CAN

	default Y

	---help---

	  Enables the common framework for platform CAN drivers with Netlink

	  support. This is the standard library for CAN drivers.

	  If unsure, say Y.

config CAN_CALC_BITTIMING

	bool "CAN bit-timing calculation"

	depends on CAN_DEV

	default Y

	---help---

	  If enabled, CAN bit-timing parameters will be calculated for the

	  bit-rate specified via Netlink argument "bitrate" when the device

	  get started. This works fine for the most common CAN controllers

	  with standard bit-rates but may fail for exotic bit-rates or CAN

	  source clock frequencies. Disabling saves some space, but then the

	  bit-timing parameters must be specified directly using the Netlink

	  arguments "tq", "prop_seg", "phase_seg1", "phase_seg2" and "sjw".

	  If unsure, say Y.

config CAN_DEBUG_DEVICES

	bool "CAN devices debugging messages"

	depends on CAN

#

obj-$(CONFIG_CAN_VCAN)		+= vcan.o

obj-$(CONFIG_CAN_DEV)		+= can-dev.o

can-dev-y			:= dev.o

ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG

/*

 * 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");