[U-Boot] [PATCH 0/3] Bring in new I2C framework

[Heiko Schocher <hs@denx.de>]

Hello Simon,

Simon Glass wrote:
> This series provides Heiko's upgraded I2C framework from a few years ago.
> I hope that we can bring this in and move boards over to it as time
> permits, rather than switching everything in one fell swoop which never
> happens.

Ok, lets try it!

> To show it working I have enabled it for Tegra in a very rough way. It
> seems fine with my limited testing.

Great! Thanks! Patches for other i2c drivers can be found here:

http://git.denx.de/?p=u-boot/u-boot-i2c.git;a=shortlog;h=refs/heads/multibus_v2_20111112

They just need a rebase and an update to your changes (and of course
some tests)

> In terms of changes, I have just fixed some checkpatch errors and fiddled
> with a couple of function signatures.
> 
> I will start a thread on the list with a few thoughts on this series
> at some point.

Ok, thanks. Here some thoughts comming in my mind:

- Why a "cur_adap" added in gd_t:
  - This points allways to the current used i2c adapter.
  - because gd_t is writeable when running in flash,
    complete multiadapter/multibus functionality is
    usable, when running in flash, which is needed for
    some SoCs.
  - using a pointer brings faster accesses to the i2c_adapter_t
    struct and saves some bytes here and there.

- init from a i2c controller:
  In current code all i2c controllers, as a precaution,
  getting initialized. In the new code, a i2c controller
  gets only initialized if it is used. This is done in
  i2c_set_bus_num().

  Also, with this approach, we can easy add in a second step,
  a i2c_deinit() function, called from i2c_set_bus_num(),
  so we can easy deactivate a no longer used controller.

- added "hw_adapnr" in i2c_adapter_t struct:
  when for example a CPU has more then one i2c controller
  we can use this variable to differentiate which
  controller the actual i2c adapter uses.

- Maybe we should add a base_addr field in struct i2c_adapter?
  This would help for SoCs, who have more then one identical
  controller, just differ in their base_addr...
  (Currently I made a function, or an array which returns
  the base_addr, dependend on "hw_adapnr"). We should drop
  this, and introduce a "base_addr" field.

[...]

bye,
Heiko
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