[U-Boot-Users] multiple i2c controllers

Wolfgang Denk wd at denx.de
Thu Sep 2 23:20:54 CEST 2004


Dear Andy,

in message <2acbd3e404090213583c7c9e6 at mail.gmail.com> you wrote:
> I've been looking into adding support for a system that has 2 i2c
> controllers accessible by the processor to u-boot.  Has anyone done
> something like this?  Does u-boot's current i2c infrastructure support
> the idea of two separate i2c busses?

No, this is not supported yet. But I think it should be  possible  to
add this in a compatible way.

For example, we could use a notation of "[bus:]chip" addresses so the
existing commands in the i2* family will continue to work on  systems
with  a single I2C bus, and on multi-bus systems you just add the bus
number to the device address separated by a colon.  For  example,  to
address  the  device  with  chip address 0x50 on bus 1 you would type
"imd 1:50 ..."; omitting the bus specifier would access  the  default
I2C bus. For simplicity, we can define that this is the same as bus 0
always.  If you have time to play around, you could add a default bus
environment variable.

This would also work for example with the eeprom command; we could use
the "bus:" extension in the offset part, like:

	eeprom read 100000 1:400 100

What do you think?

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
There is is no reason for any individual to have a computer in  their
home.      -- Ken Olsen (President of Digital Equipment Corporation),
              Convention of the World Future Society, in Boston, 1977




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