On Mon, 15 Dec 2008, Timur Tabi wrote:
ksi@koi8.net wrote:
On Mon, 15 Dec 2008, Wolfgang Denk wrote:
Are you going to implement support for multiple I2C busses on some
boards?
I'm working on something like this now so it would be nice to
coordinate our
efforts somehow...
Yes, my goal is to add low-level i2c functions that take an i2c bus as a parameter. So instead of
i2c_set_bus_num(1); i2c_read(...);
you can do
i2c_read(1, ...)
or something like that. My goal is to eliminate i2c_set_bus_num() and everything related to it.
It sounds like we're working on something very similar. This is very low-priority for me, though.
That looks similar. But why do you want to remove i2c_set_bus_num()? I think it would be less work to keep it. This way you can leave 90% or so of existing I2C code unchanged by setting bus number to 0 at init. In your case you will have to find each and every call to i2c_read... and change it to the new format that includes bus number in parameters list.
My idea is to have global bus number variable in a single place and a single i2c_set_bus_num() that can be excluded for most boards with a single bus with #ifdef...
Then, we could use some kind of array of I2C structures each containing pointers to appropriate i2c-{read,write,probe,init}() functions with generic i2c functions just calling those pointers using bus number as index into that array.
That would allow for unlimited number of different adapters for any board. Initial code for initializing such an array would have to go into each and every $(BOARD).c board specific file.
We could even make some default #ifdef'd structure that would've included automagically if something like CONFIG_I2C_MULTIBUS was not defined thus making most of the boards (actually almost all of them) work without modifications.
Please let me know what you think...
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