On Sun, 7 Dec 2008, Wolfgang Denk wrote:
Dear ksi@koi8.net,
In message Pine.LNX.4.64ksi.0812062213500.4343@home-gw.koi8.net you wrote:
As for the SM502, it is a multi-function chip that has more than just
video.
I'm writing an I2C driver for it right now and I want to ask you guys
for
your opinion.
That's not new - the SM501 is pretty similar.
As a matter of fact, SM501 is an older, now nonexistent version of SM502. Its support in U-Boot is rudimentary. I'd rather removed that old sm501.c altogether and replaced it with a new sm502.c. That should work for old SM501 chips if there are still any in existence.
Support is much better in Linux kernel -- it is almost fully supported out of the box, video, USB, sound etc.
MPC8548 has _TWO_ I2C controllers and it is taken care of in fsl_i2c.c
by
defining a "bus number." There is a function that one uses to set a
bus for
consecutive operations with i2c_read() and friends (they do NOT take a
bus
number as a parameter.) That means one sets a bus and then all the operations are done on that bus until it is changed again.
That's the general idea, also for example for device handling: we set a current device (or bus) with one command, and then continue to use that.
This might be OK but it is definitely not portable and SOC-specific.
In my
I think the "this" here refers to the specific implementation, not the general approach, right?
Yes.
case I have a _THIRD_ I2C bus off of SM502... What do you think would
be a
best approach to address this:
a.) Rewrite _ALL_ I2C code to make those i2c_read() etc. functions to
take
an additional parameter, bus numberb.) Make a global var i2c_bus or something and add a global function
kinda
i2c_set_bus() so all i2c_read()/i2c_write() functions use thatvariable
c.) Add a third bus for SM502 I2C adapter to fsl_i2c.c (horrible hack)
d.) Make SM502 I2C a totally separate entity with its own set of
functions
(like sm502_i2c_read() etc.)Please tell what you think. I personally lean towards option b.) but I
might
be wrong :)
I agree.
OK, so I'll take that route.
And there is another useful part of SM502 that's begging for
implementation
-- USB controller with legacy KBD/Mouse support...
Feel free to submit patches :-)
Sure, but there are other things that must me done before that USB. I need Silicon Image Sil3124A SATA driver first :)
--- ****************************************************************** * KSI@home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * ******************************************************************