Re: CAN Driver

[Marc Kleine-Budde <mkl@pengutronix.de>]

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Hello,

I've put the linux-can mailinglist on Cc.

On 12/06/2012 08:35 AM, Puneet Sharma wrote:
> Can you guide me how to implement system wide per CAN device
> filterting in driver code.

Here is my old mail with some thoughts:

From my point of view it should become a per device callback, which you
(admin, i.e. the root user) can set when the device is down. You have to
extend the CAN netlink interface [1].

Each device should identify what kind and how many hardware filters it
supports:
a) mask+id
b) just id
c) ...
Analogue to ctrlmode [2][3].

The requested filers are transferred into the kernel via netlink, but
you have to figure out how to encode a variable length list (netfilter
has probably a solution for this). Then the code in can_changelink() [4]
should check if the transferred filter is supported on that hardware.
Then, during open the driver should code the filters into hardware, on
at91 it should be done in at91_setup_mailboxes [5][6].

Marc

[1] http://lxr.free-electrons.com/source/drivers/net/can/dev.c#L585
[2] http://lxr.free-electrons.com/source/include/linux/can/netlink.h#L81
[3] http://lxr.free-electrons.com/source/drivers/net/can/dev.c#L724
[4] http://lxr.free-electrons.com/source/drivers/net/can/dev.c#L633
[5] http://lxr.free-electrons.com/source/drivers/net/can/at91_can.c#L418
[6] http://lxr.free-electrons.com/source/drivers/net/can/at91_can.c#L336

> We also want to test CAN controller in u-boot. Can you help me out to
> write some test cases which can test the CAN controller on a basic
> level.

If you just want to do testing, I suggest, don't do it in u-boot. I
think it's more complicated to port a CAN driver to u-boot, than to boot
linux and do the tests there.

Marc
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