PM / Domains: Store the provider in the PM domain structure

It is possible that a device has more than one provider of PM domains
and to support the removal of a PM domain by provider, it is necessary
to store a reference to the provider in the PM domain structure.
Therefore, store a reference to the firmware node handle in the PM
domain structure and populate it when providers (only device-tree based
providers are currently supported by PM domains) are registered.

Please note that when removing PM domains, it is necessary to verify
that the PM domain provider has been removed from the list of providers
before the PM domain can be removed. To do this add another member to
the PM domain structure that indicates if the provider is present and
set this member accordingly when providers are added and removed.

Initialise the 'provider' and 'has_provider' members of the
generic_pm_domain structure when a PM domains is added by calling
pm_genpd_init().
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/domain.c

@@ -1306,6 +1306,8 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
 	genpd->device_count = 0;
 	genpd->max_off_time_ns = -1;
 	genpd->max_off_time_changed = true;
+	genpd->provider = NULL;
+	genpd->has_provider = false;
 	genpd->domain.ops.runtime_suspend = genpd_runtime_suspend;
 	genpd->domain.ops.runtime_resume = genpd_runtime_resume;
 	genpd->domain.ops.prepare = pm_genpd_prepare;
@@ -1491,6 +1493,11 @@ int of_genpd_add_provider_simple(struct device_node *np,
 	if (pm_genpd_present(genpd))
 		ret = genpd_add_provider(np, genpd_xlate_simple, genpd);
 
+	if (!ret) {
+		genpd->provider = &np->fwnode;
+		genpd->has_provider = true;
+	}
+
 	mutex_unlock(&gpd_list_lock);
 
 	return ret;
@@ -1506,7 +1513,7 @@ int of_genpd_add_provider_onecell(struct device_node *np,
 				  struct genpd_onecell_data *data)
 {
 	unsigned int i;
-	int ret;
+	int ret = -EINVAL;
 
 	if (!np || !data)
 		return -EINVAL;
@@ -1514,13 +1521,26 @@ int of_genpd_add_provider_onecell(struct device_node *np,
 	mutex_lock(&gpd_list_lock);
 
 	for (i = 0; i < data->num_domains; i++) {
-		if (!pm_genpd_present(data->domains[i])) {
-			mutex_unlock(&gpd_list_lock);
-			return -EINVAL;
-		}
+		if (!pm_genpd_present(data->domains[i]))
+			goto error;
+
+		data->domains[i]->provider = &np->fwnode;
+		data->domains[i]->has_provider = true;
 	}
 
 	ret = genpd_add_provider(np, genpd_xlate_onecell, data);
+	if (ret < 0)
+		goto error;
+
+	mutex_unlock(&gpd_list_lock);
+
+	return 0;
+
+error:
+	while (i--) {
+		data->domains[i]->provider = NULL;
+		data->domains[i]->has_provider = false;
+	}
 
 	mutex_unlock(&gpd_list_lock);
 
@@ -1535,10 +1555,21 @@ EXPORT_SYMBOL_GPL(of_genpd_add_provider_onecell);
 void of_genpd_del_provider(struct device_node *np)
 {
 	struct of_genpd_provider *cp;
+	struct generic_pm_domain *gpd;
 
+	mutex_lock(&gpd_list_lock);
 	mutex_lock(&of_genpd_mutex);
 	list_for_each_entry(cp, &of_genpd_providers, link) {
 		if (cp->node == np) {
+			/*
+			 * For each PM domain associated with the
+			 * provider, set the 'has_provider' to false
+			 * so that the PM domain can be safely removed.
+			 */
+			list_for_each_entry(gpd, &gpd_list, gpd_list_node)
+				if (gpd->provider == &np->fwnode)
+					gpd->has_provider = false;
+
 			list_del(&cp->link);
 			of_node_put(cp->node);
 			kfree(cp);
@@ -1546,6 +1577,7 @@ void of_genpd_del_provider(struct device_node *np)
 		}
 	}
 	mutex_unlock(&of_genpd_mutex);
+	mutex_unlock(&gpd_list_lock);
 }
 EXPORT_SYMBOL_GPL(of_genpd_del_provider);
 

include/linux/pm_domain.h

@@ -51,6 +51,8 @@ struct generic_pm_domain {
 	struct mutex lock;
 	struct dev_power_governor *gov;
 	struct work_struct power_off_work;
+	struct fwnode_handle *provider;	/* Identity of the domain provider */
+	bool has_provider;
 	const char *name;
 	atomic_t sd_count;	/* Number of subdomains with power "on" */
 	enum gpd_status status;	/* Current state of the domain */