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Message-Id: <20260122-pmdomain-hierarchy-onecell-v5-1-76855ec856bd@baylibre.com>
Date: Thu, 22 Jan 2026 17:14:00 -0800
From: "Kevin Hilman (TI)" <khilman@...libre.com>
To: Ulf Hansson <ulf.hansson@...aro.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Sudeep Holla <sudeep.holla@....com>,
Cristian Marussi <cristian.marussi@....com>
Cc: devicetree@...r.kernel.org, linux-pm@...r.kernel.org,
arm-scmi@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Subject: [PATCH RFC v5 1/2] pmdomain: core: support domain hierarchy via
power-domain-map
Add of_genpd_[add|remove]_subdomain_map() helper functions to support
hierarchical PM domains defined by using power-domains-map
property (c.f. nexus node maps in DT spec, section 2.5.1).
This enables PM domain providers with #power-domain-cells > 0 to
establish subdomain relationships via the power-domain-map property,
which was not previously possible.
These new helper functions:
- uses an OF helper to iterate to over entries in power-domain-map
- For each mapped entry: extracts child specifier, resolves parent phandle,
extracts parent specifier args, and establishes subdomain relationship
- Calls genpd_[add|remove]_subdomain() with proper gpd_list_lock mutex protection
Example from k3-am62l.dtsi:
scmi_pds: protocol@11 {
#power-domain-cells = <1>;
power-domain-map = <15 &MAIN_PD>, /* TIMER0 */
<19 &WKUP_PD>; /* WKUP_TIMER0 */
};
MAIN_PD: power-controller-main {
#power-domain-cells = <0>;
};
WKUP_PD: power-controller-main {
#power-domain-cells = <0>;
};
This allows SCMI power domain 15 to become a subdomain of MAIN_PD, and
domain 19 to become a subdomain of WKUP_PD.
Signed-off-by: Kevin Hilman (TI) <khilman@...libre.com>
---
drivers/pmdomain/core.c | 160 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/pm_domain.h | 16 ++++++++++++++++
2 files changed, 176 insertions(+)
diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
index bf82775f6a67..cee7fbbda829 100644
--- a/drivers/pmdomain/core.c
+++ b/drivers/pmdomain/core.c
@@ -3556,6 +3556,166 @@ static struct device_driver genpd_provider_drv = {
.suppress_bind_attrs = true,
};
+/**
+ * of_genpd_remove_subdomain_map - Remove subdomain relationships from map
+ *
+ * @np: pointer to parent node containing map property
+ * @data: pointer to PM domain onecell data
+ *
+ * Iterate over entries in a power-domain-map, and remove the subdomain
+ * relationships that were previously established by of_genpd_add_subdomain_map().
+ * This allows cleanup during driver removal or error handling.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+int of_genpd_remove_subdomain_map(struct device_node *np,
+ struct genpd_onecell_data *data)
+{
+ struct generic_pm_domain *genpd, *parent_genpd;
+ struct of_phandle_args child_args, parent_args;
+ int index = 0;
+ int ret = 0;
+ u32 child_index;
+
+ if (!np || !data)
+ return -EINVAL;
+
+ /* Iterate through power-domain-map entries using the OF helper */
+ while (!of_parse_map_iter(np, "power-domain", &index,
+ &child_args, &parent_args)) {
+ /* Extract the child domain index from the child specifier */
+ if (child_args.args_count < 1) {
+ of_node_put(parent_args.np);
+ continue;
+ }
+ child_index = child_args.args[0];
+
+ /* Validate child domain index */
+ if (child_index >= data->num_domains) {
+ of_node_put(parent_args.np);
+ continue;
+ }
+
+ genpd = data->domains[child_index];
+ if (!genpd) {
+ of_node_put(parent_args.np);
+ continue;
+ }
+
+ /* Get parent power domain from provider */
+ mutex_lock(&gpd_list_lock);
+
+ parent_genpd = genpd_get_from_provider(&parent_args);
+ if (IS_ERR(parent_genpd)) {
+ mutex_unlock(&gpd_list_lock);
+ of_node_put(parent_args.np);
+ dev_warn(&genpd->dev, "failed to get parent domain for removal\n");
+ continue;
+ }
+
+ /* Remove subdomain relationship */
+ ret = pm_genpd_remove_subdomain(parent_genpd, genpd);
+ mutex_unlock(&gpd_list_lock);
+ of_node_put(parent_args.np);
+
+ if (ret)
+ dev_warn(&genpd->dev, "failed to remove as subdomain of %s: %d\n",
+ parent_genpd->name, ret);
+ else
+ dev_dbg(&genpd->dev, "removed as subdomain of %s\n",
+ parent_genpd->name);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(of_genpd_remove_subdomain_map);
+
+/**
+ * of_genpd_add_subdomain_map - Parse and map child PM domains
+ *
+ * @np: pointer to parent node containing map property
+ * @data: pointer to PM domain onecell data
+ *
+ * Iterate over entries in a power-domain-map, and add them as
+ * children of the parent domain. If any child fails to be added,
+ * all previously added children are removed to maintain atomicity.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+int of_genpd_add_subdomain_map(struct device_node *np,
+ struct genpd_onecell_data *data)
+{
+ struct generic_pm_domain *genpd, *parent_genpd;
+ struct of_phandle_args child_args, parent_args;
+ int index = 0;
+ int ret = 0;
+ u32 child_index;
+
+ if (!np || !data)
+ return -EINVAL;
+
+ /* Iterate through power-domain-map entries using the OF helper */
+ while (!of_parse_map_iter(np, "power-domain", &index,
+ &child_args, &parent_args)) {
+ /* Extract the child domain index from the child specifier */
+ if (child_args.args_count < 1) {
+ of_node_put(parent_args.np);
+ ret = -EINVAL;
+ goto cleanup;
+ }
+ child_index = child_args.args[0];
+
+ /* Validate child domain index */
+ if (child_index >= data->num_domains) {
+ of_node_put(parent_args.np);
+ pr_debug("map's child index (%u) > number of domains (%u). Skipping.\n",
+ child_index, data->num_domains);
+ ret = -EINVAL;
+ goto cleanup;
+ }
+
+ genpd = data->domains[child_index];
+ if (!genpd) {
+ of_node_put(parent_args.np);
+ continue;
+ }
+
+ /* Get parent power domain from provider and establish subdomain relationship */
+ mutex_lock(&gpd_list_lock);
+
+ parent_genpd = genpd_get_from_provider(&parent_args);
+ if (IS_ERR(parent_genpd)) {
+ mutex_unlock(&gpd_list_lock);
+ of_node_put(parent_args.np);
+ ret = PTR_ERR(parent_genpd);
+ dev_err(&genpd->dev, "failed to get parent domain: %d\n", ret);
+ goto cleanup;
+ }
+
+ ret = genpd_add_subdomain(parent_genpd, genpd);
+ mutex_unlock(&gpd_list_lock);
+ of_node_put(parent_args.np);
+
+ if (ret) {
+ dev_err(&genpd->dev, "failed to add as subdomain of %s: %d\n",
+ parent_genpd->name, ret);
+ goto cleanup;
+ }
+
+ dev_dbg(&genpd->dev, "added as subdomain of %s\n",
+ parent_genpd->name);
+ }
+
+ return 0;
+
+cleanup:
+ /* Remove all successfully added subdomains using the removal function */
+ pr_err("rolling back child map additions due to error: %d\n", ret);
+ of_genpd_remove_subdomain_map(np, data);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(of_genpd_add_subdomain_map);
+
static int __init genpd_bus_init(void)
{
int ret;
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 93ba0143ca47..3baf224e4f24 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -463,6 +463,10 @@ int of_genpd_add_subdomain(const struct of_phandle_args *parent_spec,
int of_genpd_remove_subdomain(const struct of_phandle_args *parent_spec,
const struct of_phandle_args *subdomain_spec);
struct generic_pm_domain *of_genpd_remove_last(struct device_node *np);
+int of_genpd_add_subdomain_map(struct device_node *np,
+ struct genpd_onecell_data *data);
+int of_genpd_remove_subdomain_map(struct device_node *np,
+ struct genpd_onecell_data *data);
int of_genpd_parse_idle_states(struct device_node *dn,
struct genpd_power_state **states, int *n);
void of_genpd_sync_state(struct device_node *np);
@@ -505,6 +509,18 @@ static inline int of_genpd_remove_subdomain(const struct of_phandle_args *parent
return -ENODEV;
}
+static inline int of_genpd_add_subdomain_map(struct device_node *np,
+ struct genpd_onecell_data *data)
+{
+ return -ENODEV;
+}
+
+static inline int of_genpd_remove_subdomain_map(struct device_node *np,
+ struct genpd_onecell_data *data)
+{
+ return -ENODEV;
+}
+
static inline int of_genpd_parse_idle_states(struct device_node *dn,
struct genpd_power_state **states, int *n)
{
--
2.51.0
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