[PATCH v1 02/13] pmdomain: mediatek: Refactor bus protection regmaps retrieval

[Fei Shao]

On Mon, Jun 23, 2025 at 8:02 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno at collabora.com> wrote:
>
> In preparation to add support for new generation SoCs like MT8196,
> MT6991 and other variants, which require to set bus protection on
> different busses than the ones found on legacy chips, and to also
> simplify and reduce memory footprint of this driver, refactor the
> mechanism to retrieve and use the bus protection regmaps.
>
> This is done by removing the three pointers to struct regmap from
> struct scpsys_domain (allocated for each power domain) and moving
> them to the main struct scpsys (allocated per driver instance) as
> an array of pointers to regmap named **bus_prot.
>
> That deprecates the old devicetree properties to grab phandles to
> the three predefined busses (infracfg, infracfg-nao and smi) and
> replaces it with a new property "mediatek,bus-protection" that is
> meant to be an array of phandles holding the same busses where
> required (for now - for legacy SoCs).
>
> The new bus protection phandles are indexed by the bus_prot_index
> member of struct scpsys, used to map "bus type" (ex.: infra, smi,
> etc) to the specific *bus_prot[x] element.
>
> While the old per-power-domain regmap pointers were removed, the
> support for old devicetree was retained by still checking if the
> new property (in DT) and new-style declaration (in SoC specific
> platform data) are both present at probe time.
>
> If those are not present, a lookup for the old properties will be
> done in all of the children of the power controller, and pointers
> to regmaps will be retrieved with the old properties, but then
> will be internally remapped to follow the new style regmap anyway
> as to let this driver benefit of the memory footprint reduction.
>
> Finally, it was necessary to change macros in mtk-pm-domains.h and
> in mt8365-pm-domains.h to make use of the new style bus protection
> declaration, as the actual HW block is now recognized not by flags
> but by its own scpsys_bus_prot_block enumeration.
>
> The BUS_PROT_(STA)_COMPONENT_{INFRA,INFRA_NAO,SMI} flags were also
> removed since they are now unused, and because that enumeration was
> initially meant to vary the logic of bus protection and not the bus
> where work is performed, anyway!
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>
> ---

<snip>

>
> +static int scpsys_get_bus_protection_legacy(struct device *dev, struct scpsys *scpsys)
> +{
> +       const u8 bp_blocks[3] = {
> +               BUS_PROT_BLOCK_INFRA, BUS_PROT_BLOCK_SMI, BUS_PROT_BLOCK_INFRA_NAO
> +       };
> +       struct device_node *np = dev->of_node;
> +       struct device_node *node, *smi_np;
> +       int num_regmaps = 0, i, j;
> +       struct regmap *regmap[3];
> +
> +       /*
> +        * Legacy code retrieves a maximum of three bus protection handles:
> +        * some may be optional, or may not be, so the array of bp blocks
> +        * that is normally passed in as platform data must be dynamically
> +        * built in this case.
> +        *
> +        * Here, try to retrieve all of the regmaps that the legacy code
> +        * supported and then count the number of the ones that are present,
> +        * this makes it then possible to allocate the array of bus_prot
> +        * regmaps and convert all to the new style handling.
> +        */
> +       node = of_find_node_with_property(np, "mediatek,infracfg");
> +       if (node) {
> +               regmap[0] = syscon_regmap_lookup_by_phandle(node, "mediatek,infracfg");
> +               of_node_put(node);
> +               num_regmaps++;
> +               if (IS_ERR(regmap[0]))
> +                       return dev_err_probe(dev, PTR_ERR(regmap[0]),
> +                                            "%pOF: failed to get infracfg regmap\n",
> +                                            node);
> +       } else {
> +               regmap[0] = NULL;
> +       }
> +
> +       node = of_find_node_with_property(np, "mediatek,smi");
> +       if (node) {
> +               smi_np = of_parse_phandle(node, "mediatek,smi", 0);
> +               of_node_put(node);
> +               if (!smi_np)
> +                       return -ENODEV;
> +
> +               regmap[1] = device_node_to_regmap(smi_np);
> +               num_regmaps++;
> +               of_node_put(smi_np);
> +               if (IS_ERR(regmap[1]))
> +                       return dev_err_probe(dev, PTR_ERR(regmap[1]),
> +                                            "%pOF: failed to get SMI regmap\n",
> +                                            node);
> +       } else {
> +               regmap[1] = NULL;
> +       }
> +
> +       node = of_find_node_with_property(np, "mediatek,infracfg-nao");
> +       if (node) {
> +               regmap[2] = syscon_regmap_lookup_by_phandle(node, "mediatek,infracfg-nao");
> +               num_regmaps++;
> +               of_node_put(node);
> +               if (IS_ERR(regmap[2]))
> +                       return dev_err_probe(dev, PTR_ERR(regmap[2]),
> +                                            "%pOF: failed to get infracfg regmap\n",
> +                                            node);
> +       } else {
> +               regmap[2] = NULL;
> +       }
> +
> +       scpsys->bus_prot = devm_kmalloc_array(dev, num_regmaps,
> +                                             sizeof(*scpsys->bus_prot), GFP_KERNEL);
> +       if (!scpsys->bus_prot)
> +               return -ENOMEM;
> +
> +       for (i = 0, j = 0; i < num_regmaps; i++) {

Did you mean BUS_PROT_BLOCK_COUNT?
Consider a case where only regmap[2] is configured.

Regards,
Fei

> +               enum scpsys_bus_prot_block bp_type;
> +
> +               if (!regmap[i])
> +                       continue;
> +
> +               bp_type = bp_blocks[i];
> +               scpsys->bus_prot_index[bp_type] = j;
> +               scpsys->bus_prot[j] = regmap[i];
> +
> +               j++;
> +       }
> +
> +       return 0;
> +}
> +

<snip>