Date:	Mon, 07 Sep 2009 13:06:39 +0200
From:	Sebastian Haas <haas@...-wuensche.com>
To:	Oliver Hartkopp <oliver@...tkopp.net>
CC:	Wolfgang Grandegger <wg@...ndegger.com>, Greg KH <greg@...ah.com>,
	Linux Netdev List <netdev@...r.kernel.org>,
	Felipe Balbi <me@...ipebalbi.com>
Subject: Re: Staging: cpc-usb CAN driver TODO list

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Okay, thanks for the tips. Lets see what I can create today.

Sebastian

Oliver Hartkopp schrieb:
> Wolfgang Grandegger wrote:
>> On 09/07/2009 10:01 AM, Sebastian Haas wrote:
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>>> Wolfgang,
>>>
>>> Wolfgang Grandegger schrieb:
>>>> Hi Sebastian,
>>>>
>>>> On 09/07/2009 07:56 AM, Sebastian Haas wrote:
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>>>>> Oliver,
>>>>>
>>>>> I'm not yet sure how to actually start the development. There is so
>>>>> much
>>>>> to do, and I've not much time to spend on this, unfortunately. Because
>>>>> of this I can't rewrite the whole driver on my own in order to get a
>>>>> Socket-CAN driver but I can provide support, review patches, rent
>>>>> devices and make tests here.
>>>>>
>>>>> Oliver, you are not familiar with USB and I'm not very familiar with
>>>>> CAN
>>>>> netdev internals, why not combining these twos. You are writing the CAN
>>>>> part and write the USB part.
>>>>>
>>>>> I'll also write a specification which contains any information you need
>>>>> to develop a CAN driver for the device (commands, sequences, error
>>>>> handling).
>>>> Alternatively, EMS Wuensche could also hire an expert doing the job ;-).
>>>> Note that we do a lot of Socket-CAN work in our free time, which is a
>>>> limited resource. Progress depends on funding to a certain extend.
>>> Money is also a limited resource. ;-)
>>>
>>> Let's become serious again, I know and respect that many of Socket-CAN
>>> and the Staging developers spend their free time working on it. We will
>>> of course work on the driver, but since we've not much time it may take
>>> several months. If someone wants to help, we would be very glad and
>>> happy to support the person as far as we can with devices, answers and
>>> tests.
>> OK, no problem. I really appreciate your support for Socket-CAN so far.
> 
> Indeed. Me too.
> 
> I tried to take a second look into cpc-usb_drv.c and i would suggest to remove
> all the procfs and the chardev stuff and then create a CAN netdev when you
> identified an USB node analogue to
> 
>         /* Detect available channels */
>         for (i = 0; i < EMS_PCMCIA_MAX_CHAN; i++) {
>                 dev = alloc_sja1000dev(0);
>                 if (dev == NULL) {
>                         err = -ENOMEM;
>                         goto failure_cleanup;
>                 }
> 
>                 card->net_dev[i] = dev;
>                 priv = netdev_priv(dev);
>                 priv->priv = card;
>                 SET_NETDEV_DEV(dev, &pdev->dev);
> 
> as you know from your ems_pcmcia.c driver
> 
> and
> 
> struct net_device *alloc_sja1000dev(int sizeof_priv)
> {
>         struct net_device *dev;
>         struct sja1000_priv *priv;
> 
>         dev = alloc_candev(sizeof(struct sja1000_priv) + sizeof_priv);
>         if (!dev)
>                 return NULL;
> 
>         priv = netdev_priv(dev);
> 
>         priv->dev = dev;
>         priv->can.bittiming_const = &sja1000_bittiming_const;
>         priv->can.do_set_bittiming = sja1000_set_bittiming;
>         priv->can.do_set_mode = sja1000_set_mode;
> 
>         if (sizeof_priv)
>                 priv->priv = (void *)priv + sizeof(struct sja1000_priv);
> 
>         return dev;
> }
> 
> as you know from the sja1000.c (which can probably be used for the
> LPC2119_PRODUCT_ID we should try to implement first).
> 
> Then we need something like this stuff
> 
> static const struct net_device_ops sja1000_netdev_ops = {
>         .ndo_open               = sja1000_open,
>         .ndo_stop               = sja1000_close,
>         .ndo_start_xmit         = sja1000_start_xmit,
> };
> 
> int register_sja1000dev(struct net_device *dev)
> {
>         if (!sja1000_probe_chip(dev))
>                 return -ENODEV;
> 
>         dev->netdev_ops = &sja1000_netdev_ops;
> 
>         dev->flags |= IFF_ECHO; /* we support local echo */
> 
>         set_reset_mode(dev);
>         chipset_init(dev);
> 
>         return register_candev(dev);
> }
> 
> from sja1000.c
> 
> And then we have an USB CAN node that has a belonging CAN netdevice (maybe
> there is something else we can look at that's used in other USB ethernet
> adapters).
> 
> I know from the PEAK USB driver at
> 
> http://www.peak-system.com/fileadmin/media/linux/files/peak-linux-driver.6.11.tar.gz
> 
> that i just needed to duplicate and modify the usb rx/tx stuff and redirect
> the CAN frames into the network stack. But this PEAK driver does not have a
> netlink configuration interface and can only be taken as a limited example ...
> 
> I assume, when the driver (cpc_usb.c or ems_usb.c analogue to the ems_pcmcia.c
> ?) is prepared as described above, one can go and connect the rx/tx dataflow
> and the netlink configuration.
> 
> Unfortunately i'm short of time the next two weeks but maybe you can start and
> create such a new C-file (probably based on ems_pcmcia.c) ?
> 
> Best regards,
> Oliver
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-- 
EMS Dr. Thomas Wuensche e.K.
Sonnenhang 3
85304 Ilmmuenster
HRA Neuburg a.d. Donau, HR-Nr. 70.106
Phone: +49-8441-490260
Fax  : +49-8441-81860
http://www.ems-wuensche.com
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