Thank you for all the help it seems I have everything working and am able to
hit sub 20uS accuracy. Is there any concern with my HR timer ISR interrupting
a currently pending CAN message that is only partially done, thus sending my
packet in "the middle" of another one? Or is each packet in the can driver
sent as an atomic event?
If you are curious, here were my initial results:
(1584977760.000001) can0 00050F93 [6] 00 02 5F D7 78 5E
(1584977761.999995) can0 00050F93 [6] 00 02 61 D7 78 5E
(1584977763.999993) can0 00050F93 [6] 00 02 63 D7 78 5E
(1584977766.000002) can0 00050F93 [6] 00 02 65 D7 78 5E
(1584977767.999996) can0 00050F93 [6] 00 02 67 D7 78 5E
(1584977769.999999) can0 00050F93 [6] 00 02 69 D7 78 5E
(1584977772.000002) can0 00050F93 [6] 00 02 6B D7 78 5E
(1584977774.000001) can0 00050F93 [6] 00 02 6D D7 78 5E
(1584977776.000000) can0 00050F93 [6] 00 02 6F D7 78 5E
(1584977778.000000) can0 00050F93 [6] 00 02 71 D7 78 5E
(1584977779.999997) can0 00050F93 [6] 00 02 73 D7 78 5E
(1584977781.999999) can0 00050F93 [6] 00 02 75 D7 78 5E
(1584977783.999996) can0 00050F93 [6] 00 02 77 D7 78 5E
(1584977786.000022) can0 00050F93 [6] 00 02 79 D7 78 5E
(1584977788.000000) can0 00050F93 [6] 00 02 7B D7 78 5E
And my current functioning code:
int SendCanTime(struct timespec *tsCurrentTime) {
struct can_frame frame;
struct can_frame *cf = &frame;
struct sk_buff *skb;
int thetime = tsCurrentTime->tv_sec;
struct net_device *dev;
int err;
// Find the netdevice named can0
dev = __dev_get_by_name(&init_net,"can0");
if (!dev)
return -ENXIO;
// Create skb
skb = alloc_can_skb(dev, &cf);
if (!skb) {
dev_put(dev);
return 1;
}
skb->dev = dev;
// Set up can frame
cf->can_id = 0x00050F93 | CAN_EFF_FLAG;
cf->can_dlc = 6;
cf->data[0] = 0x00;
cf->data[1] = 0x02;
memcpy(cf->data+2, &thetime, sizeof(int));
err = can_send(skb, 1);
if(err) {
dev_put(skb->dev);
return 1;
}
return 0;
}
^
^
On Sun, Mar 22, 2020 at 1:55 PM Oliver Hartkopp <socketcan@xxxxxxxxxxxx> wrote:
>
>
>
> On 22/03/2020 19.03, Robert Barrows wrote:
> > Thank you for all the direction Oliver, I think I am on the correct path,
> > but now have can_send returning with a "-1" (ERESTART). I used raw_sendmsg
> > as a template for this and cut out (hopefully) unneeded code, but I am
> > concerned I cut out something I needed. Would you mind taking another look?
> >
> > Thanks.
> >
> > int SendCanTime(struct timespec *tsCurrentTime) {
> >
> > struct sk_buff *skb;
> > struct can_frame *frame = kmalloc(sizeof (struct can_frame), GFP_KERNEL);
> > struct net_device *dev;
> > int err = 0;
> > int thetime = tsCurrentTime->tv_sec;
> >
> > // Set up can frame
> > frame->can_id = 0x00050F93 | CAN_EFF_FLAG;
> > frame->can_dlc = 6;
> > frame->data[0] = 0x00;
> > frame->data[1] = 0x02;
> > memcpy(frame->data+2, &thetime, sizeof(int));
> >
> > // Find the netdevice named can0
> > read_lock(&dev_base_lock);
> > dev = first_net_device(&init_net);
> > while (!strcmp(dev->name, "can0")) {
> > printk(KERN_INFO "found [%s]\n", dev->name);
> > dev = next_net_device(dev);
> > }
> > read_unlock(&dev_base_lock);
>
> What does this return when you don't have can0 in the system??
>
> You should use
> __dev_get_by_name()
> here.
> https://elixir.bootlin.com/linux/latest/source/net/core/dev.c#L762
>
> And check for success :-)
>
>
> >
> > if (!dev)
> > return -ENXIO;
> >
> > // Create skb
> > skb = alloc_can_skb(dev, &frame);
> > if (!skb)
> > goto put_dev;
> >
> > skb->dev = dev;
> >
> > err = can_send(skb, 0);
> >
> > dev_put(dev);
> >
> > if (err)
> > goto send_failed;
> >
> > return 0;
> >
> > //kfree_skb(skb);
> > put_dev:
> > dev_put(dev);
> > send_failed:
> > return err;
> >
> > }
> > ^
> >
