Re: [PATCH v2 0/4] hw/i2c: Adds pca954x i2c mux switch device

[Corey Minyard <cminyard@mvista.com>]

On Fri, Apr 09, 2021 at 09:25:41AM -0700, Patrick Venture wrote:
> The i2c mux device pca954x implements two devices:
>  - the pca9546 and pca9548.
> 
> v2:
>  - the core i2c bus now calls a match method on each i2c child, which
>  by default will only check for a match against itself.
>  - the pca954x device overrides the i2c device match method to search
>  the children for each of its buses that are active.
>  - the pca954x device now owns an i2c bus for each channel, allowing
>  the normal device model to attach devices to the channels.

I like this design.  Avoiding hacking into the bus code is a bonus.

Can these devices really have multiple channels enabled at the same
time?  That seems strange, but I guess that could be useful.

I'm not sure if you need to add a vmstate structure for this.  In
general most new devices have them; if it's ever included on an x86
system (or a system with vmstate transfer capability, probably more than
x86) that will become an issue.  I'm not sure what the expectations are,
though.

-corey

> 
> Patrick Venture (4):
>   hw/i2c: name I2CNode list in I2CBus
>   hw/i2c: add match method for device search
>   hw/i2c: move search to i2c_scan_bus method
>   hw/i2c: add pca954x i2c-mux switch
> 
>  MAINTAINERS                      |   6 +
>  hw/i2c/Kconfig                   |   4 +
>  hw/i2c/core.c                    |  55 ++++--
>  hw/i2c/i2c_mux_pca954x.c         | 290 +++++++++++++++++++++++++++++++
>  hw/i2c/meson.build               |   1 +
>  hw/i2c/trace-events              |   5 +
>  include/hw/i2c/i2c.h             |  16 +-
>  include/hw/i2c/i2c_mux_pca954x.h |  19 ++
>  8 files changed, 382 insertions(+), 14 deletions(-)
>  create mode 100644 hw/i2c/i2c_mux_pca954x.c
>  create mode 100644 include/hw/i2c/i2c_mux_pca954x.h
> 
> -- 
> 2.31.1.295.g9ea45b61b8-goog
>