From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Christian Gagneraud <chgans@gmail.com>,
linux-can <linux-can@vger.kernel.org>
Subject: Re: New USB driver, looking for advice
Date: Tue, 8 Dec 2020 15:59:43 +0100 [thread overview]
Message-ID: <a13ab81e-ad20-0405-6935-ecd748233bc5@pengutronix.de> (raw)
In-Reply-To: <CABxGUThzGkCerMBTuA95TCs49hjHg+O-u3Z_c8=RZGJ8bVQjRQ@mail.gmail.com>
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On 12/7/20 3:57 AM, Christian Gagneraud wrote:
> I'm looking at creating a new CAN driver for a USB device [1]. This device
> has a custom protocol over bulk endpoints. I was able to create a simple
> driver, based on usb-skeleton.c that allows to speak this protocol by opening
> a custom har device.
Do you already have code available somewhere?
> I've been looking at the current implementation in [2], I think my device is
> a bit special, you cannot read CAN frames w/o sending a 'read' command, so i
> need some sort of polling. AFAIK, the Linux USB stack provides that for me,
> except that the device won't read anything unless you send it a command.
I don't know if you have to implement the polling yourself or if there is a
polling helper. I'll ask my co-workers.
Is that a Interrupt Transfer Endpoint or a normal Bulk Endpoint?
> I have the feeling that current drivers are for devices that can
> return data by just scheduling read transfer.
Yes. Current drivers get notified by the device, if there is a CAN frame waiting.
> Anyone would have a clue on how these drivers work, and if my device
> is really that special?
Yes, your device is quite special :)
> Any hint, point out or reading pointers are much appreciated.
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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next prev parent reply other threads:[~2020-12-08 15:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-07 2:57 New USB driver, looking for advice Christian Gagneraud
2020-12-08 14:59 ` Marc Kleine-Budde [this message]
2020-12-09 11:03 ` Marc Kleine-Budde
2020-12-09 20:24 ` Christian Gagneraud
2020-12-10 7:36 ` Marc Kleine-Budde
2020-12-10 22:26 ` Christian Gagneraud
2020-12-11 8:39 ` Marc Kleine-Budde
2021-02-18 2:14 ` Christian Gagneraud
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