Wolfgang Grandegger wrote:
Hi Matthias,
Matthias Fuchs wrote:
Hi Wolfgang,
Wolfgang Grandegger wrote:
You have to define the real CAN system clock, which is 16/2 = 8 Mhz for
most SJA 1000 hardware even if the oscillator is running at 16 MHz. I
will add some reasonable note to rtcan_dev.h
Is there any special reason for this? Wouldn't it be more meaningful
to pass the SJA1000 externally applied clock frequency? I can imagine
that others will also run into this issue as Jan and I did yesterday ;-)
The frequency is used to calculate reasonable bit-timing parameters, not
only for SJA 1000. It's used in a similar way in the Linux socket CAN
driver.
But the value passed via module parameter "clock" could be the more
meaning full clock frequency for SJA 1000 drivers, of course.
Then we will soon have to discuss how to deal with a rtcan_isa
derivative that uses ioremapped memory instead of ports (naming,
separation or integration).
We could add a generic device similar to ISA (or extend ISA
accordingly).
The SJA1000 isa driver is very simple - and so is the modified version
for the memory mapped SJA1000. I think that merging both ways of
access to the SJA1000 into a single driver will make the code much
more dirty. I would prefer different source files (= different drivers).
I agree.
It would be a compromise to add support for boards that use some kind
of indirect addressing to access the SJA1000 (address + data register)
into the isa and mem versions of the driver.
Fine if this could be done in a generic way. We also should add a
generic PCI driver sooner than later.
One more proposal: I think many (old) ISA drivers name the module
parameter for the ISA io port "io" instead of "isa". For the memory
mapped SJA1000 driver, I'd like to call the parameter "mem".
Well, I cannot remember why I used the name "isa". Common is "io" or
"port" or "ioport", indeed. "io" and "mem" or "ioport" and "iomem" would
be fine for me.
Wolfgang.
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