Re: [PATCH v7 3/6] reset: mchp: sparx5: Map cpu-syscon locally in case of LAN966x

[Steen Hegelund <steen.hegelund@xxxxxxxxxxxxx>]

Hi Herve,

On Thu, 2024-10-03 at 10:16 +0200, Herve Codina wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you
> know the content is safe
> 
> In the LAN966x PCI device use case, the syscon API cannot be used as
> it does not support device removal [1]. A syscon device is a core
> "system" device and not a device available in some addon boards and
> so,
> it is not supposed to be removed. The syscon API follows this
> assumption
> but this assumption is no longer valid in the LAN966x use case.
> 
> In order to avoid the use of the syscon API and so, support for
> removal,
> use a local mapping of the syscon device.
> 
> Link:
> https://lore.kernel.org/all/20240923100741.11277439@xxxxxxxxxxx/ [1]
> Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
> ---
>  drivers/reset/reset-microchip-sparx5.c | 35
> +++++++++++++++++++++++++-
>  1 file changed, 34 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/reset/reset-microchip-sparx5.c
> b/drivers/reset/reset-microchip-sparx5.c
> index 636e85c388b0..48a62d5da78d 100644
> --- a/drivers/reset/reset-microchip-sparx5.c
> +++ b/drivers/reset/reset-microchip-sparx5.c
> @@ -62,6 +62,28 @@ static const struct reset_control_ops
> sparx5_reset_ops = {
>         .reset = sparx5_reset_noop,
>  };
> 
> +static const struct regmap_config mchp_lan966x_syscon_regmap_config
> = {
> +       .reg_bits = 32,
> +       .val_bits = 32,
> +       .reg_stride = 4,
> +};
> +
> +static struct regmap *mchp_lan966x_syscon_to_regmap(struct device
> *dev,
> +                                                   struct
> device_node *syscon_np)
> +{
> +       struct regmap_config regmap_config =
> mchp_lan966x_syscon_regmap_config;
> +       resource_size_t size;
> +       void __iomem *base;
> +
> +       base = devm_of_iomap(dev, syscon_np, 0, &size);
> +       if (IS_ERR(base))
> +               return ERR_CAST(base);
> +
> +       regmap_config.max_register = size - 4;
> +
> +       return devm_regmap_init_mmio(dev, base, &regmap_config);
> +}
> +
>  static int mchp_sparx5_map_syscon(struct platform_device *pdev, char
> *name,
>                                   struct regmap **target)
>  {
> @@ -72,7 +94,18 @@ static int mchp_sparx5_map_syscon(struct
> platform_device *pdev, char *name,
>         syscon_np = of_parse_phandle(pdev->dev.of_node, name, 0);
>         if (!syscon_np)
>                 return -ENODEV;
> -       regmap = syscon_node_to_regmap(syscon_np);
> +
> +       /*
> +        * The syscon API doesn't support syscon device removal.
> +        * When used in LAN966x PCI device, the cpu-syscon device
> needs to be
> +        * removed when the PCI device is removed.
> +        * In case of LAN966x, map the syscon device locally to
> support the
> +        * device removal.
> +        */
> +       if (of_device_is_compatible(pdev->dev.of_node,
> "microchip,lan966x-switch-reset"))
> +               regmap = mchp_lan966x_syscon_to_regmap(&pdev->dev,
> syscon_np);
> +       else
> +               regmap = syscon_node_to_regmap(syscon_np);
>         of_node_put(syscon_np);
>         if (IS_ERR(regmap)) {
>                 err = PTR_ERR(regmap);
> --
> 2.46.1
> 

This looks good to me.

Reviewed-by: Steen Hegelund <Steen.Hegelund@xxxxxxxxxxxxx>

BR
Steen