@@ -68,6 +68,21 @@ properties:
by the given provider should be subdomains of the domain specified
by this binding.
+ power-domains-child-ids:
+ $ref: /schemas/types.yaml#/definitions/uint32-array
+ description:
+ An array of child domain IDs that correspond to the power-domains
+ property. This property is only applicable to power domain providers
+ with #power-domain-cells > 0 (i.e., providers that supply multiple
+ power domains). It specifies which of the provider's child domains
+ should be associated with each parent domain listed in the power-domains
+ property. The number of elements in this array must match the number of
+ phandles in the power-domains property. Each element specifies the child
+ domain ID (index) that should be made a subdomain of the corresponding
+ parent domain. This enables hierarchical power domain structures where
+ different child domains from the same provider can have different
+ parent domains.
+
required:
- "#power-domain-cells"
@@ -133,3 +148,27 @@ examples:
min-residency-us = <7000>;
};
};
+
+ - |
+ // Example of power-domains-child-ids usage
+ MAIN_PD: main-power-controller {
+ compatible = "foo,main-power-controller";
+ #power-domain-cells = <0>;
+ };
+
+ WKUP_PD: wkup-power-controller {
+ compatible = "foo,wkup-power-controller";
+ #power-domain-cells = <0>;
+ };
+
+ scmi_pds: protocol@11 {
+ reg = <0x11>;
+ #power-domain-cells = <1>;
+ power-domains = <&MAIN_PD>, <&WKUP_PD>;
+ power-domains-child-ids = <15>, <19>;
+ };
+
+ // In the above example:
+ // - Child domain 15 (scmi_pds 15) becomes a subdomain of MAIN_PD
+ // - Child domain 19 (scmi_pds 19) becomes a subdomain of WKUP_PD
+ // - Other child domains (0-14, 16-18, 20+) have no parent relationship
@@ -2441,6 +2441,9 @@ static LIST_HEAD(of_genpd_providers);
/* Mutex to protect the list above. */
static DEFINE_MUTEX(of_genpd_mutex);
+static int of_genpd_parse_child_ids(struct device_node *np,
+ struct genpd_onecell_data *data);
+
/**
* genpd_xlate_simple() - Xlate function for direct node-domain mapping
* @genpdspec: OF phandle args to map into a PM domain
@@ -2635,6 +2638,14 @@ int of_genpd_add_provider_onecell(struct device_node *np,
if (ret < 0)
goto error;
+ /* Parse power-domains-child-ids property to establish parent-child relationships */
+ ret = of_genpd_parse_child_ids(np, data);
+ if (ret < 0 && ret != -ENOENT) {
+ pr_err("Failed to parse power-domains-child-ids for %pOF: %d\n", np, ret);
+ of_genpd_del_provider(np);
+ goto error;
+ }
+
return 0;
error:
@@ -2734,6 +2745,106 @@ static struct generic_pm_domain *genpd_get_from_provider(
return genpd;
}
+/**
+ * of_genpd_parse_child_ids() - Parse power-domains-child-ids property
+ * @np: Device node pointer associated with the PM domain provider.
+ * @data: Pointer to the onecell data associated with the PM domain provider.
+ *
+ * Parse the power-domains and power-domains-child-ids properties to establish
+ * parent-child relationships for PM domains. The power-domains property lists
+ * parent domains, and power-domains-child-ids lists which child domain IDs
+ * should be associated with each parent.
+ *
+ * Returns 0 on success, -ENOENT if properties don't exist, or negative error code.
+ */
+static int of_genpd_parse_child_ids(struct device_node *np,
+ struct genpd_onecell_data *data)
+{
+ struct of_phandle_args parent_args;
+ struct generic_pm_domain *parent_genpd, *child_genpd;
+ u32 *child_ids;
+ int num_parents, num_child_ids, i, ret;
+
+ /* Check if both properties exist */
+ num_parents = of_count_phandle_with_args(np, "power-domains", "#power-domain-cells");
+ if (num_parents <= 0)
+ return -ENOENT;
+
+ num_child_ids = of_property_count_u32_elems(np, "power-domains-child-ids");
+ if (num_child_ids <= 0)
+ return -ENOENT;
+
+ if (num_parents != num_child_ids) {
+ pr_err("power-domains (%d) and power-domains-child-ids (%d) count mismatch for %pOF\n",
+ num_parents, num_child_ids, np);
+ return -EINVAL;
+ }
+
+ child_ids = kcalloc(num_child_ids, sizeof(*child_ids), GFP_KERNEL);
+ if (!child_ids)
+ return -ENOMEM;
+
+ ret = of_property_read_u32_array(np, "power-domains-child-ids", child_ids, num_child_ids);
+ if (ret) {
+ pr_err("Failed to read power-domains-child-ids for %pOF: %d\n", np, ret);
+ goto out_free;
+ }
+
+ /* For each parent domain, establish parent-child relationship */
+ for (i = 0; i < num_parents; i++) {
+ ret = of_parse_phandle_with_args(np, "power-domains",
+ "#power-domain-cells", i, &parent_args);
+ if (ret) {
+ pr_err("Failed to parse parent domain %d for %pOF: %d\n", i, np, ret);
+ goto out_free;
+ }
+
+ /* Get the parent domain */
+ parent_genpd = genpd_get_from_provider(&parent_args);
+ of_node_put(parent_args.np);
+ if (IS_ERR(parent_genpd)) {
+ pr_err("Failed to get parent domain %d for %pOF: %ld\n",
+ i, np, PTR_ERR(parent_genpd));
+ ret = PTR_ERR(parent_genpd);
+ goto out_free;
+ }
+
+ /* Validate child ID is within bounds */
+ if (child_ids[i] >= data->num_domains) {
+ pr_err("Child ID %u out of bounds (max %u) for parent %d in %pOF\n",
+ child_ids[i], data->num_domains - 1, i, np);
+ ret = -EINVAL;
+ goto out_free;
+ }
+
+ /* Get the child domain */
+ child_genpd = data->domains[child_ids[i]];
+ if (!child_genpd) {
+ pr_err("Child domain %u is NULL for parent %d in %pOF\n",
+ child_ids[i], i, np);
+ ret = -EINVAL;
+ goto out_free;
+ }
+
+ /* Establish parent-child relationship */
+ ret = genpd_add_subdomain(parent_genpd, child_genpd);
+ if (ret) {
+ pr_err("Failed to add child domain %u to parent %d in %pOF: %d\n",
+ child_ids[i], i, np, ret);
+ goto out_free;
+ }
+
+ pr_debug("Added child domain %u (%s) to parent %s for %pOF\n",
+ child_ids[i], child_genpd->name, parent_genpd->name, np);
+ }
+
+ ret = 0;
+
+out_free:
+ kfree(child_ids);
+ return ret;
+}
+
/**
* of_genpd_add_device() - Add a device to an I/O PM domain
* @genpdspec: OF phandle args to use for look-up PM domain
Currently, PM domains can only support hierarchy for simple providers (e.g. ones with #power-domain-cells = 0). Add support for oncell providers as well by adding a new property `power-domains-child-ids` to describe the parent/child relationship. For example, an SCMI PM domain provider might be a subdomain of multiple parent domains. In this example, the parent domains are MAIN_PD and WKUP_PD: scmi_pds: protocol@11 { reg = <0x11>; #power-domain-cells = <1>; power-domains = <&MAIN_PD>, <&WKUP_PD>; power-domains-child-ids = <15>, <19>; }; With the new property, child domain 15 (scmi_pds 15) becomes a subdomain of MAIN_PD, and child domain 19 (scmi_pds 19) becomes a subdomain of WKUP_PD. Note: this idea was previously discussed on the arm-scmi mailing list[1] where this approach was proposed by Ulf. This is my initial attempt at implementing it for discussion. I'm definitely a noob at adding support new DT properties, so I got some help from an AI friend named Claude in writing this code, so feedback on the apprach is welcomed. [1] https://lore.kernel.org/arm-scmi/CAPDyKFo_P129sVirHHYjOQT+QUmpymcRJme9obzKJeRgO7B-1A@mail.gmail.com/ Signed-off-by: Kevin Hilman <khilman@baylibre.com> --- Documentation/devicetree/bindings/power/power-domain.yaml | 39 ++++++++++++++++++++++++++++++++ drivers/pmdomain/core.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 150 insertions(+) --- base-commit: 0ff41df1cb268fc69e703a08a57ee14ae967d0ca change-id: 20250528-pmdomain-hierarchy-onecell-a46fad47d855 Best regards,