[RFC V2 0/4] prototype: switch I2C IP cores at runtime

[RFC V2 0/4] prototype: switch I2C IP cores at runtime

[Wolfram Sang]

Some SoC (like Renesas RCar Gen2) have different I2C IP cores with different
feature sets. This is an experimental patch series to let those different IP
cores access the same I2C bus at runtime. Finally, we have some code to talk
about :) Unlike previous sketched versions, this one does not require a
remove/probe-cycle of I2C bus drivers which would mean complete
reinitialization of all connected I2C clients. However, the first two patches
need serious discussion. So, have a look if you are interested...

Please have a look at the individual patches for changes since last version.
This is mainly code improvements and rebase to v4.0-rc4 for easier testing and
to keep discussion alive :) These patches are only sent to the sh-list for now.
I'd like to have consensus here before involving people from the outside.


Wolfram Sang (4):
  pinctrl: allow to unselect a state
  i2c: mux: add function to reparent a mux
  ARM: shmobile: r8a7790: lager: add i2c-demuxer to dts
  i2c: mux: demux-pinctrl: add driver

 .../devicetree/bindings/i2c/i2c-demux-pinctrl.txt  |  79 ++++++++
 arch/arm/boot/dts/r8a7790-lager.dts                |  66 +++++--
 drivers/i2c/i2c-mux.c                              |   8 +
 drivers/i2c/muxes/Kconfig                          |   6 +
 drivers/i2c/muxes/Makefile                         |   2 +
 drivers/i2c/muxes/i2c-demux-pinctrl.c              | 220 +++++++++++++++++++++
 drivers/pinctrl/core.c                             |  34 ++--
 include/linux/i2c-mux.h                            |   2 +
 include/linux/pinctrl/consumer.h                   |   5 +
 9 files changed, 391 insertions(+), 31 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt
 create mode 100644 drivers/i2c/muxes/i2c-demux-pinctrl.c

-- 
2.1.4

Re: [RFC V2 0/4] prototype: switch I2C IP cores at runtime

[Magnus Damm]

Hi Wolfram,

On Tue, Mar 17, 2015 at 4:15 PM, Wolfram Sang <wsa@the-dreams.de> wrote:
> Some SoC (like Renesas RCar Gen2) have different I2C IP cores with different
> feature sets. This is an experimental patch series to let those different IP
> cores access the same I2C bus at runtime. Finally, we have some code to talk
> about :) Unlike previous sketched versions, this one does not require a
> remove/probe-cycle of I2C bus drivers which would mean complete
> reinitialization of all connected I2C clients. However, the first two patches
> need serious discussion. So, have a look if you are interested...
>
> Please have a look at the individual patches for changes since last version.
> This is mainly code improvements and rebase to v4.0-rc4 for easier testing and
> to keep discussion alive :) These patches are only sent to the sh-list for now.
> I'd like to have consensus here before involving people from the outside.

Thanks. I think this looks rather clean myself!

This approach would also in theory allow using a GPIO bitbang driver
as one alternative I2C master, right?

If so then I'm happy because we can then keep a single DTB and yet
generic distro-kernels should be able to include GPIO bitbang support
in their kernels but may exclude other variants of I2C master
controller drivers.

Cheers,

/ magnus