2 * Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
3 * Copyright (C) 2006 Andrey Volkov, Varma Electronics
4 * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the version 2 of the GNU General Public License
8 * as published by the Free Software Foundation
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 #include <linux/module.h>
21 #include <linux/kernel.h>
22 #include <linux/slab.h>
23 #include <linux/netdevice.h>
24 #include <linux/if_arp.h>
25 #include <linux/can.h>
26 #include <linux/can/dev.h>
27 #include <linux/can/netlink.h>
28 #include <net/rtnetlink.h>
30 #define MOD_DESC "CAN device driver interface"
32 MODULE_DESCRIPTION(MOD_DESC
);
33 MODULE_LICENSE("GPL v2");
34 MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");
36 #ifdef CONFIG_CAN_CALC_BITTIMING
37 #define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
40 * Bit-timing calculation derived from:
42 * Code based on LinCAN sources and H8S2638 project
43 * Copyright 2004-2006 Pavel Pisa - DCE FELK CVUT cz
44 * Copyright 2005 Stanislav Marek
45 * email: pisa@cmp.felk.cvut.cz
47 * Calculates proper bit-timing parameters for a specified bit-rate
48 * and sample-point, which can then be used to set the bit-timing
49 * registers of the CAN controller. You can find more information
50 * in the header file linux/can/netlink.h.
52 static int can_update_spt(const struct can_bittiming_const
*btc
,
53 int sampl_pt
, int tseg
, int *tseg1
, int *tseg2
)
55 *tseg2
= tseg
+ 1 - (sampl_pt
* (tseg
+ 1)) / 1000;
56 if (*tseg2
< btc
->tseg2_min
)
57 *tseg2
= btc
->tseg2_min
;
58 if (*tseg2
> btc
->tseg2_max
)
59 *tseg2
= btc
->tseg2_max
;
60 *tseg1
= tseg
- *tseg2
;
61 if (*tseg1
> btc
->tseg1_max
) {
62 *tseg1
= btc
->tseg1_max
;
63 *tseg2
= tseg
- *tseg1
;
65 return 1000 * (tseg
+ 1 - *tseg2
) / (tseg
+ 1);
68 static int can_calc_bittiming(struct net_device
*dev
, struct can_bittiming
*bt
)
70 struct can_priv
*priv
= netdev_priv(dev
);
71 const struct can_bittiming_const
*btc
= priv
->bittiming_const
;
72 long rate
, best_rate
= 0;
73 long best_error
= 1000000000, error
= 0;
74 int best_tseg
= 0, best_brp
= 0, brp
= 0;
75 int tsegall
, tseg
= 0, tseg1
= 0, tseg2
= 0;
76 int spt_error
= 1000, spt
= 0, sampl_pt
;
79 if (!priv
->bittiming_const
)
82 /* Use CIA recommended sample points */
83 if (bt
->sample_point
) {
84 sampl_pt
= bt
->sample_point
;
86 if (bt
->bitrate
> 800000)
88 else if (bt
->bitrate
> 500000)
94 /* tseg even = round down, odd = round up */
95 for (tseg
= (btc
->tseg1_max
+ btc
->tseg2_max
) * 2 + 1;
96 tseg
>= (btc
->tseg1_min
+ btc
->tseg2_min
) * 2; tseg
--) {
97 tsegall
= 1 + tseg
/ 2;
98 /* Compute all possible tseg choices (tseg=tseg1+tseg2) */
99 brp
= priv
->clock
.freq
/ (tsegall
* bt
->bitrate
) + tseg
% 2;
100 /* chose brp step which is possible in system */
101 brp
= (brp
/ btc
->brp_inc
) * btc
->brp_inc
;
102 if ((brp
< btc
->brp_min
) || (brp
> btc
->brp_max
))
104 rate
= priv
->clock
.freq
/ (brp
* tsegall
);
105 error
= bt
->bitrate
- rate
;
106 /* tseg brp biterror */
109 if (error
> best_error
)
113 spt
= can_update_spt(btc
, sampl_pt
, tseg
/ 2,
115 error
= sampl_pt
- spt
;
118 if (error
> spt_error
)
122 best_tseg
= tseg
/ 2;
130 /* Error in one-tenth of a percent */
131 error
= (best_error
* 1000) / bt
->bitrate
;
132 if (error
> CAN_CALC_MAX_ERROR
) {
133 dev_err(dev
->dev
.parent
,
134 "bitrate error %ld.%ld%% too high\n",
135 error
/ 10, error
% 10);
138 dev_warn(dev
->dev
.parent
, "bitrate error %ld.%ld%%\n",
139 error
/ 10, error
% 10);
143 /* real sample point */
144 bt
->sample_point
= can_update_spt(btc
, sampl_pt
, best_tseg
,
147 v64
= (u64
)best_brp
* 1000000000UL;
148 do_div(v64
, priv
->clock
.freq
);
150 bt
->prop_seg
= tseg1
/ 2;
151 bt
->phase_seg1
= tseg1
- bt
->prop_seg
;
152 bt
->phase_seg2
= tseg2
;
156 bt
->bitrate
= priv
->clock
.freq
/ (bt
->brp
* (tseg1
+ tseg2
+ 1));
160 #else /* !CONFIG_CAN_CALC_BITTIMING */
161 static int can_calc_bittiming(struct net_device
*dev
, struct can_bittiming
*bt
)
163 dev_err(dev
->dev
.parent
, "bit-timing calculation not available\n");
166 #endif /* CONFIG_CAN_CALC_BITTIMING */
169 * Checks the validity of the specified bit-timing parameters prop_seg,
170 * phase_seg1, phase_seg2 and sjw and tries to determine the bitrate
171 * prescaler value brp. You can find more information in the header
172 * file linux/can/netlink.h.
174 static int can_fixup_bittiming(struct net_device
*dev
, struct can_bittiming
*bt
)
176 struct can_priv
*priv
= netdev_priv(dev
);
177 const struct can_bittiming_const
*btc
= priv
->bittiming_const
;
181 if (!priv
->bittiming_const
)
184 tseg1
= bt
->prop_seg
+ bt
->phase_seg1
;
187 if (bt
->sjw
> btc
->sjw_max
||
188 tseg1
< btc
->tseg1_min
|| tseg1
> btc
->tseg1_max
||
189 bt
->phase_seg2
< btc
->tseg2_min
|| bt
->phase_seg2
> btc
->tseg2_max
)
192 brp64
= (u64
)priv
->clock
.freq
* (u64
)bt
->tq
;
193 if (btc
->brp_inc
> 1)
194 do_div(brp64
, btc
->brp_inc
);
195 brp64
+= 500000000UL - 1;
196 do_div(brp64
, 1000000000UL); /* the practicable BRP */
197 if (btc
->brp_inc
> 1)
198 brp64
*= btc
->brp_inc
;
199 bt
->brp
= (u32
)brp64
;
201 if (bt
->brp
< btc
->brp_min
|| bt
->brp
> btc
->brp_max
)
204 alltseg
= bt
->prop_seg
+ bt
->phase_seg1
+ bt
->phase_seg2
+ 1;
205 bt
->bitrate
= priv
->clock
.freq
/ (bt
->brp
* alltseg
);
206 bt
->sample_point
= ((tseg1
+ 1) * 1000) / alltseg
;
211 int can_get_bittiming(struct net_device
*dev
, struct can_bittiming
*bt
)
213 struct can_priv
*priv
= netdev_priv(dev
);
216 /* Check if the CAN device has bit-timing parameters */
217 if (priv
->bittiming_const
) {
219 /* Non-expert mode? Check if the bitrate has been pre-defined */
221 /* Determine bit-timing parameters */
222 err
= can_calc_bittiming(dev
, bt
);
224 /* Check bit-timing params and calculate proper brp */
225 err
= can_fixup_bittiming(dev
, bt
);
234 * Local echo of CAN messages
236 * CAN network devices *should* support a local echo functionality
237 * (see Documentation/networking/can.txt). To test the handling of CAN
238 * interfaces that do not support the local echo both driver types are
239 * implemented. In the case that the driver does not support the echo
240 * the IFF_ECHO remains clear in dev->flags. This causes the PF_CAN core
241 * to perform the echo as a fallback solution.
243 static void can_flush_echo_skb(struct net_device
*dev
)
245 struct can_priv
*priv
= netdev_priv(dev
);
246 struct net_device_stats
*stats
= &dev
->stats
;
249 for (i
= 0; i
< priv
->echo_skb_max
; i
++) {
250 if (priv
->echo_skb
[i
]) {
251 kfree_skb(priv
->echo_skb
[i
]);
252 priv
->echo_skb
[i
] = NULL
;
254 stats
->tx_aborted_errors
++;
260 * Put the skb on the stack to be looped backed locally lateron
262 * The function is typically called in the start_xmit function
263 * of the device driver. The driver must protect access to
264 * priv->echo_skb, if necessary.
266 void can_put_echo_skb(struct sk_buff
*skb
, struct net_device
*dev
,
269 struct can_priv
*priv
= netdev_priv(dev
);
271 BUG_ON(idx
>= priv
->echo_skb_max
);
273 /* check flag whether this packet has to be looped back */
274 if (!(dev
->flags
& IFF_ECHO
) || skb
->pkt_type
!= PACKET_LOOPBACK
) {
279 if (!priv
->echo_skb
[idx
]) {
280 struct sock
*srcsk
= skb
->sk
;
282 if (atomic_read(&skb
->users
) != 1) {
283 struct sk_buff
*old_skb
= skb
;
285 skb
= skb_clone(old_skb
, GFP_ATOMIC
);
294 /* make settings for echo to reduce code in irq context */
295 skb
->protocol
= htons(ETH_P_CAN
);
296 skb
->pkt_type
= PACKET_BROADCAST
;
297 skb
->ip_summed
= CHECKSUM_UNNECESSARY
;
300 /* save this skb for tx interrupt echo handling */
301 priv
->echo_skb
[idx
] = skb
;
303 /* locking problem with netif_stop_queue() ?? */
304 dev_err(dev
->dev
.parent
, "%s: BUG! echo_skb is occupied!\n",
309 EXPORT_SYMBOL_GPL(can_put_echo_skb
);
312 * Get the skb from the stack and loop it back locally
314 * The function is typically called when the TX done interrupt
315 * is handled in the device driver. The driver must protect
316 * access to priv->echo_skb, if necessary.
318 void can_get_echo_skb(struct net_device
*dev
, unsigned int idx
)
320 struct can_priv
*priv
= netdev_priv(dev
);
322 BUG_ON(idx
>= priv
->echo_skb_max
);
324 if (priv
->echo_skb
[idx
]) {
325 netif_rx(priv
->echo_skb
[idx
]);
326 priv
->echo_skb
[idx
] = NULL
;
329 EXPORT_SYMBOL_GPL(can_get_echo_skb
);
332 * Remove the skb from the stack and free it.
334 * The function is typically called when TX failed.
336 void can_free_echo_skb(struct net_device
*dev
, unsigned int idx
)
338 struct can_priv
*priv
= netdev_priv(dev
);
340 BUG_ON(idx
>= priv
->echo_skb_max
);
342 if (priv
->echo_skb
[idx
]) {
343 kfree_skb(priv
->echo_skb
[idx
]);
344 priv
->echo_skb
[idx
] = NULL
;
347 EXPORT_SYMBOL_GPL(can_free_echo_skb
);
350 * CAN device restart for bus-off recovery
352 void can_restart(unsigned long data
)
354 struct net_device
*dev
= (struct net_device
*)data
;
355 struct can_priv
*priv
= netdev_priv(dev
);
356 struct net_device_stats
*stats
= &dev
->stats
;
358 struct can_frame
*cf
;
361 BUG_ON(netif_carrier_ok(dev
));
364 * No synchronization needed because the device is bus-off and
365 * no messages can come in or go out.
367 can_flush_echo_skb(dev
);
369 /* send restart message upstream */
370 skb
= alloc_can_err_skb(dev
, &cf
);
375 cf
->can_id
|= CAN_ERR_RESTARTED
;
380 stats
->rx_bytes
+= cf
->can_dlc
;
383 dev_dbg(dev
->dev
.parent
, "restarted\n");
384 priv
->can_stats
.restarts
++;
386 /* Now restart the device */
387 err
= priv
->do_set_mode(dev
, CAN_MODE_START
);
389 netif_carrier_on(dev
);
391 dev_err(dev
->dev
.parent
, "Error %d during restart", err
);
394 int can_restart_now(struct net_device
*dev
)
396 struct can_priv
*priv
= netdev_priv(dev
);
399 * A manual restart is only permitted if automatic restart is
400 * disabled and the device is in the bus-off state
402 if (priv
->restart_ms
)
404 if (priv
->state
!= CAN_STATE_BUS_OFF
)
407 /* Runs as soon as possible in the timer context */
408 mod_timer(&priv
->restart_timer
, jiffies
);
416 * This functions should be called when the device goes bus-off to
417 * tell the netif layer that no more packets can be sent or received.
418 * If enabled, a timer is started to trigger bus-off recovery.
420 void can_bus_off(struct net_device
*dev
)
422 struct can_priv
*priv
= netdev_priv(dev
);
424 dev_dbg(dev
->dev
.parent
, "bus-off\n");
426 netif_carrier_off(dev
);
427 priv
->can_stats
.bus_off
++;
429 if (priv
->restart_ms
)
430 mod_timer(&priv
->restart_timer
,
431 jiffies
+ (priv
->restart_ms
* HZ
) / 1000);
433 EXPORT_SYMBOL_GPL(can_bus_off
);
435 static void can_setup(struct net_device
*dev
)
437 dev
->type
= ARPHRD_CAN
;
438 dev
->mtu
= sizeof(struct can_frame
);
439 dev
->hard_header_len
= 0;
441 dev
->tx_queue_len
= 10;
443 /* New-style flags. */
444 dev
->flags
= IFF_NOARP
;
445 dev
->features
= NETIF_F_NO_CSUM
;
448 struct sk_buff
*alloc_can_skb(struct net_device
*dev
, struct can_frame
**cf
)
452 skb
= netdev_alloc_skb(dev
, sizeof(struct can_frame
));
456 skb
->protocol
= htons(ETH_P_CAN
);
457 skb
->pkt_type
= PACKET_BROADCAST
;
458 skb
->ip_summed
= CHECKSUM_UNNECESSARY
;
459 *cf
= (struct can_frame
*)skb_put(skb
, sizeof(struct can_frame
));
460 memset(*cf
, 0, sizeof(struct can_frame
));
464 EXPORT_SYMBOL_GPL(alloc_can_skb
);
466 struct sk_buff
*alloc_can_err_skb(struct net_device
*dev
, struct can_frame
**cf
)
470 skb
= alloc_can_skb(dev
, cf
);
474 (*cf
)->can_id
= CAN_ERR_FLAG
;
475 (*cf
)->can_dlc
= CAN_ERR_DLC
;
479 EXPORT_SYMBOL_GPL(alloc_can_err_skb
);
482 * Allocate and setup space for the CAN network device
484 struct net_device
*alloc_candev(int sizeof_priv
, unsigned int echo_skb_max
)
486 struct net_device
*dev
;
487 struct can_priv
*priv
;
491 size
= ALIGN(sizeof_priv
, sizeof(struct sk_buff
*)) +
492 echo_skb_max
* sizeof(struct sk_buff
*);
496 dev
= alloc_netdev(size
, "can%d", can_setup
);
500 priv
= netdev_priv(dev
);
503 priv
->echo_skb_max
= echo_skb_max
;
504 priv
->echo_skb
= (void *)priv
+
505 ALIGN(sizeof_priv
, sizeof(struct sk_buff
*));
508 priv
->state
= CAN_STATE_STOPPED
;
510 init_timer(&priv
->restart_timer
);
514 EXPORT_SYMBOL_GPL(alloc_candev
);
517 * Free space of the CAN network device
519 void free_candev(struct net_device
*dev
)
523 EXPORT_SYMBOL_GPL(free_candev
);
526 * Common open function when the device gets opened.
528 * This function should be called in the open function of the device
531 int open_candev(struct net_device
*dev
)
533 struct can_priv
*priv
= netdev_priv(dev
);
535 if (!priv
->bittiming
.tq
&& !priv
->bittiming
.bitrate
) {
536 dev_err(dev
->dev
.parent
, "bit-timing not yet defined\n");
540 /* Switch carrier on if device was stopped while in bus-off state */
541 if (!netif_carrier_ok(dev
))
542 netif_carrier_on(dev
);
544 setup_timer(&priv
->restart_timer
, can_restart
, (unsigned long)dev
);
548 EXPORT_SYMBOL_GPL(open_candev
);
551 * Common close function for cleanup before the device gets closed.
553 * This function should be called in the close function of the device
556 void close_candev(struct net_device
*dev
)
558 struct can_priv
*priv
= netdev_priv(dev
);
560 if (del_timer_sync(&priv
->restart_timer
))
562 can_flush_echo_skb(dev
);
564 EXPORT_SYMBOL_GPL(close_candev
);
567 * CAN netlink interface
569 static const struct nla_policy can_policy
[IFLA_CAN_MAX
+ 1] = {
570 [IFLA_CAN_STATE
] = { .type
= NLA_U32
},
571 [IFLA_CAN_CTRLMODE
] = { .len
= sizeof(struct can_ctrlmode
) },
572 [IFLA_CAN_RESTART_MS
] = { .type
= NLA_U32
},
573 [IFLA_CAN_RESTART
] = { .type
= NLA_U32
},
574 [IFLA_CAN_BITTIMING
] = { .len
= sizeof(struct can_bittiming
) },
575 [IFLA_CAN_BITTIMING_CONST
]
576 = { .len
= sizeof(struct can_bittiming_const
) },
577 [IFLA_CAN_CLOCK
] = { .len
= sizeof(struct can_clock
) },
578 [IFLA_CAN_BERR_COUNTER
] = { .len
= sizeof(struct can_berr_counter
) },
581 static int can_changelink(struct net_device
*dev
,
582 struct nlattr
*tb
[], struct nlattr
*data
[])
584 struct can_priv
*priv
= netdev_priv(dev
);
587 /* We need synchronization with dev->stop() */
590 if (data
[IFLA_CAN_CTRLMODE
]) {
591 struct can_ctrlmode
*cm
;
593 /* Do not allow changing controller mode while running */
594 if (dev
->flags
& IFF_UP
)
596 cm
= nla_data(data
[IFLA_CAN_CTRLMODE
]);
597 if (cm
->flags
& ~priv
->ctrlmode_supported
)
599 priv
->ctrlmode
&= ~cm
->mask
;
600 priv
->ctrlmode
|= cm
->flags
;
603 if (data
[IFLA_CAN_BITTIMING
]) {
604 struct can_bittiming bt
;
606 /* Do not allow changing bittiming while running */
607 if (dev
->flags
& IFF_UP
)
609 memcpy(&bt
, nla_data(data
[IFLA_CAN_BITTIMING
]), sizeof(bt
));
610 if ((!bt
.bitrate
&& !bt
.tq
) || (bt
.bitrate
&& bt
.tq
))
612 err
= can_get_bittiming(dev
, &bt
);
615 memcpy(&priv
->bittiming
, &bt
, sizeof(bt
));
617 if (priv
->do_set_bittiming
) {
618 /* Finally, set the bit-timing registers */
619 err
= priv
->do_set_bittiming(dev
);
625 if (data
[IFLA_CAN_RESTART_MS
]) {
626 /* Do not allow changing restart delay while running */
627 if (dev
->flags
& IFF_UP
)
629 priv
->restart_ms
= nla_get_u32(data
[IFLA_CAN_RESTART_MS
]);
632 if (data
[IFLA_CAN_RESTART
]) {
633 /* Do not allow a restart while not running */
634 if (!(dev
->flags
& IFF_UP
))
636 err
= can_restart_now(dev
);
644 static size_t can_get_size(const struct net_device
*dev
)
646 struct can_priv
*priv
= netdev_priv(dev
);
649 size
= nla_total_size(sizeof(u32
)); /* IFLA_CAN_STATE */
650 size
+= sizeof(struct can_ctrlmode
); /* IFLA_CAN_CTRLMODE */
651 size
+= nla_total_size(sizeof(u32
)); /* IFLA_CAN_RESTART_MS */
652 size
+= sizeof(struct can_bittiming
); /* IFLA_CAN_BITTIMING */
653 size
+= sizeof(struct can_clock
); /* IFLA_CAN_CLOCK */
654 if (priv
->do_get_berr_counter
) /* IFLA_CAN_BERR_COUNTER */
655 size
+= sizeof(struct can_berr_counter
);
656 if (priv
->bittiming_const
) /* IFLA_CAN_BITTIMING_CONST */
657 size
+= sizeof(struct can_bittiming_const
);
662 static int can_fill_info(struct sk_buff
*skb
, const struct net_device
*dev
)
664 struct can_priv
*priv
= netdev_priv(dev
);
665 struct can_ctrlmode cm
= {.flags
= priv
->ctrlmode
};
666 struct can_berr_counter bec
;
667 enum can_state state
= priv
->state
;
669 if (priv
->do_get_state
)
670 priv
->do_get_state(dev
, &state
);
671 NLA_PUT_U32(skb
, IFLA_CAN_STATE
, state
);
672 NLA_PUT(skb
, IFLA_CAN_CTRLMODE
, sizeof(cm
), &cm
);
673 NLA_PUT_U32(skb
, IFLA_CAN_RESTART_MS
, priv
->restart_ms
);
674 NLA_PUT(skb
, IFLA_CAN_BITTIMING
,
675 sizeof(priv
->bittiming
), &priv
->bittiming
);
676 NLA_PUT(skb
, IFLA_CAN_CLOCK
, sizeof(cm
), &priv
->clock
);
677 if (priv
->do_get_berr_counter
&& !priv
->do_get_berr_counter(dev
, &bec
))
678 NLA_PUT(skb
, IFLA_CAN_BERR_COUNTER
, sizeof(bec
), &bec
);
679 if (priv
->bittiming_const
)
680 NLA_PUT(skb
, IFLA_CAN_BITTIMING_CONST
,
681 sizeof(*priv
->bittiming_const
), priv
->bittiming_const
);
689 static size_t can_get_xstats_size(const struct net_device
*dev
)
691 return sizeof(struct can_device_stats
);
694 static int can_fill_xstats(struct sk_buff
*skb
, const struct net_device
*dev
)
696 struct can_priv
*priv
= netdev_priv(dev
);
698 NLA_PUT(skb
, IFLA_INFO_XSTATS
,
699 sizeof(priv
->can_stats
), &priv
->can_stats
);
707 static int can_newlink(struct net
*src_net
, struct net_device
*dev
,
708 struct nlattr
*tb
[], struct nlattr
*data
[])
713 static struct rtnl_link_ops can_link_ops __read_mostly
= {
715 .maxtype
= IFLA_CAN_MAX
,
716 .policy
= can_policy
,
718 .newlink
= can_newlink
,
719 .changelink
= can_changelink
,
720 .get_size
= can_get_size
,
721 .fill_info
= can_fill_info
,
722 .get_xstats_size
= can_get_xstats_size
,
723 .fill_xstats
= can_fill_xstats
,
727 * Register the CAN network device
729 int register_candev(struct net_device
*dev
)
731 dev
->rtnl_link_ops
= &can_link_ops
;
732 return register_netdev(dev
);
734 EXPORT_SYMBOL_GPL(register_candev
);
737 * Unregister the CAN network device
739 void unregister_candev(struct net_device
*dev
)
741 unregister_netdev(dev
);
743 EXPORT_SYMBOL_GPL(unregister_candev
);
745 static __init
int can_dev_init(void)
749 err
= rtnl_link_register(&can_link_ops
);
751 printk(KERN_INFO MOD_DESC
"\n");
755 module_init(can_dev_init
);
757 static __exit
void can_dev_exit(void)
759 rtnl_link_unregister(&can_link_ops
);
761 module_exit(can_dev_exit
);
763 MODULE_ALIAS_RTNL_LINK("can");