Re: [PATCH v2 4/4] hw/i2c: add pca954x i2c-mux switch

[Philippe Mathieu-Daudé]

Hi Patrick,

On 4/9/21 6:25 PM, Patrick Venture wrote:
> The pca954x is an i2c mux, and this adds support for two variants of
> this device: the pca9546 and pca9548.
> 
> This device is very common on BMCs to route a different channel to each
> PCIe i2c bus downstream from the BMC.
> 
> Signed-off-by: Patrick Venture <venture@google.com>
> Reviewed-by: Hao Wu <wuhaotsh@google.com>
> Reviewed-by: Havard Skinnemoen <hskinnemoen@google.com>
> ---
>  MAINTAINERS                      |   6 +
>  hw/i2c/Kconfig                   |   4 +
>  hw/i2c/i2c_mux_pca954x.c         | 290 +++++++++++++++++++++++++++++++
>  hw/i2c/meson.build               |   1 +
>  hw/i2c/trace-events              |   5 +
>  include/hw/i2c/i2c_mux_pca954x.h |  19 ++
>  6 files changed, 325 insertions(+)
>  create mode 100644 hw/i2c/i2c_mux_pca954x.c
>  create mode 100644 include/hw/i2c/i2c_mux_pca954x.h

> diff --git a/hw/i2c/Kconfig b/hw/i2c/Kconfig
> index 09642a6dcb..8d120a25d5 100644
> --- a/hw/i2c/Kconfig
> +++ b/hw/i2c/Kconfig
> @@ -28,3 +28,7 @@ config IMX_I2C
>  config MPC_I2C
>      bool
>      select I2C
> +
> +config PCA954X
> +    bool
> +    select I2C

Do you have a circular dependency when also using:

       depends on I2C

?

> +static void pca954x_realize(DeviceState *dev, Error **errp)
> +{
> +    Pca954xState *s = PCA954X(dev);
> +    Pca954xClass *c = PCA954X_GET_CLASS(s);
> +    int i;
> +
> +    /* SMBus modules. Cannot fail. */
> +    for (i = 0; i < c->nchans; i++) {
> +        Object *obj = OBJECT(&s->channel[i]);
> +        sysbus_realize(SYS_BUS_DEVICE(obj), &error_abort);

No need to cast to Object:

           sysbus_realize(SYS_BUS_DEVICE(&s->channel[i]), &error_abort);

> +    }
> +}