Re: [RFC v5 net-next 02/13] mfd: ocelot: offer an interface for MFD children to get regmaps

Lee Jones
2021-12-29T15:24:07Z

On Sat, 18 Dec 2021, Colin Foster wrote:

> Child devices need to get a regmap from a resource struct, specifically
> from the MFD parent. The MFD parent has the interface to the hardware
> layer, which could be I2C, SPI, PCIe, etc.
>
> This is somewhat a hack... ideally child devices would interface with the
> struct device* directly, by way of a function like
> devm_get_regmap_from_resource which would be akin to
> devm_get_and_ioremap_resource. A less ideal option would be to interface
> directly with MFD to get a regmap from the parent.
>
> This solution is even less ideal than both of the two suggestions, so is
> intentionally left in a separate commit after the initial MFD addition.
>
> Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
> ---
> drivers/mfd/ocelot-core.c | 9 +++++++++
> include/soc/mscc/ocelot.h | 12 ++++++++++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/drivers/mfd/ocelot-core.c b/drivers/mfd/ocelot-core.c
> index a65619a8190b..09132ea52760 100644
> --- a/drivers/mfd/ocelot-core.c
> +++ b/drivers/mfd/ocelot-core.c
> @@ -94,6 +94,15 @@ static struct regmap *ocelot_mfd_regmap_init(struct ocelot_mfd_core *core,
> return regmap;
> }
>
> +struct regmap *ocelot_mfd_get_regmap_from_resource(struct device *dev,
> + const struct resource *res)
> +{
> + struct ocelot_mfd_core *core = dev_get_drvdata(dev);
> +
> + return ocelot_mfd_regmap_init(core, res);
> +}
> +EXPORT_SYMBOL(ocelot_mfd_get_regmap_from_resource);

This is almost certainly not the right way to do whatever it is you're
trying to do!

Please don't try to upstream "somewhat a hack"s into the Mainline
kernel.

--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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