[U-Boot] [PATCH v2 2/3] sunxi: Complete i2c support for each supported platform

[Hans de Goede <hdegoede@redhat.com>]

Hi Simon and Paul,

On 05-04-15 22:56, Paul Kocialkowski wrote:
> Le dimanche 05 avril 2015 ? 12:31 -0600, Simon Glass a ?crit :
>> Hi Paul,
>>
>> On 4 April 2015 at 14:49, Paul Kocialkowski <contact@paulk.fr> wrote:
>>> Sunxi platforms come with at least 3 TWI (I2C) controllers and some platforms
>>> even have up to 5. This adds support for every controller on each supported
>>> platform, which is especially useful when using expansion ports on single-board-
>>> computers.
>>>
>>> Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
>>> ---
>>>   arch/arm/include/asm/arch-sunxi/cpu_sun4i.h |  7 +++
>>>   arch/arm/include/asm/arch-sunxi/gpio.h      | 15 +++++-
>>>   arch/arm/include/asm/arch-sunxi/i2c.h       | 13 +++++
>>>   board/sunxi/Kconfig                         | 31 ++++++++++++
>>>   board/sunxi/board.c                         | 75 ++++++++++++++++++++++++++++-
>>>   5 files changed, 138 insertions(+), 3 deletions(-)
>>>

<snip>

>>> diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
>>> index ccc2080..d3b5bad 100644
>>> --- a/board/sunxi/Kconfig
>>> +++ b/board/sunxi/Kconfig
>>> @@ -269,6 +269,37 @@ config USB2_VBUS_PIN
>>>          ---help---
>>>          See USB1_VBUS_PIN help text.
>>>
>>> +config I2C1_ENABLE
>>> +       bool "Enable I2C/TWI controller 1"
>>> +       default n
>>> +       ---help---
>>> +       This allows enabling I2C/TWI controller 1 by muxing its pins, enabling
>>> +       its clock and setting up the bus. This is especially useful on devices
>>> +       with slaves connected to the bus or with pins exposed through e.g. an
>>> +       expansion port/header.
>>> +
>>> +config I2C2_ENABLE
>>> +       bool "Enable I2C/TWI controller 2"
>>> +       default n
>>> +       ---help---
>>> +       See I2C1_ENABLE help text.
>>> +
>>> +if MACH_SUN6I || MACH_SUN7I
>>> +config I2C3_ENABLE
>>> +       bool "Enable I2C/TWI controller 3"
>>> +       default n
>>> +       ---help---
>>> +       See I2C1_ENABLE help text.
>>> +endif
>>> +
>>> +if MACH_SUN7I
>>> +config I2C4_ENABLE
>>> +       bool "Enable I2C/TWI controller 4"
>>> +       default n
>>> +       ---help---
>>> +       See I2C1_ENABLE help text.
>>> +endif
>>
>> It seems wrong to me to add these when they are already in the device
>> tree for the board. Can we not use that?
>
> Well, Hans has a point when saying that some users may use those pins as
> GPIO while some others may use the TWI/I2C functions, so it makes sense
> to make this configurable via Kconfig instead of being statically
> defined.
>
>> If you would rather wait until we have driver model I2C on sunxi
>> (mvtwsi, I think) then I'd be happy to do the conversion. It's pretty
>> easy.
>
> I would be happy to see U-Boot on sunxi use devicetree and driver model
> for TWI/I2C as well (provided users can still configure what busses to
> enable). Still, I'd like to see this getting merged as a short term
> solution.
>
>> How can we get sunxi moved over before there is an explosion of these
>> sorts of things (as we have already seen with video options)?

I fully support moving sunxi over the devicemodel + devicetree in my
mind the following steps need to be taken:

0) Get the devicemode usb patches merged in to u-boot-dm/next
    Then on top pf u-boot-dm/next:

1) Move all the sunxi boards over to use dm + dt like we're already
    doing for the pcduino

2) Start using dm for usb on sunxi

3) Enable ohci support on sunxi boards next to ehci

4) Move other stuff over on a step by step basis

Note that we will likely have a mix of Kconfig + devicetree for
quite a while though since certain things which we support in
u-boot are not supported in the kernel yet so they do not have
stable devicetree bindings yet, video being the big one here.

> I think Hans will know better (than myself) how to do this right.

Not really, other then having the the generic outline above in my head,
I do not really have much experience with the devicemodel in u-boot yet,
also I do not have all that much time to work one this, so help on
this from you would certainly be very welcome. I can answer any sunxi
questions you may have, and I believe it is safe to say that Simon
can answer any device-model questions you may have.

Regards,

Hans

p.s.

Paul I'm still fine with taking your i2c patchset upstream for now,
but I do agree with Simon that we need to move to the device model
and the sooner we do that the better.