pmdomain: core: Set the required dev for a required OPP during genpd attach

JIRA: https://issues.redhat.com/browse/RHEL-75956

commit e130ca9
Author: Ulf Hansson <ulf.hansson@linaro.org>
Date:   Wed Oct 2 14:22:27 2024 +0200

    pmdomain: core: Set the required dev for a required OPP during genpd attach

    In the single PM domain case there is no need for platform code to specify
    the index of the corresponding required OPP in DT, as the index must be
    zero. This allows us to assign a required dev for the required OPP from
    genpd, while attaching a device to its PM domain.

    In this way, we can remove some of the genpd specific code in the OPP core
    for the single PM domain case. Although, this cleanup is made from a
    subsequent change.

    Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
    Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
    Link: https://lore.kernel.org/r/20241002122232.194245-7-ulf.hansson@linaro.org

Signed-off-by: José Expósito <jexposit@redhat.com>

Author: jexposit

drivers/pmdomain/core.c

@@ -1727,6 +1727,7 @@ static void genpd_free_dev_data(struct device *dev,
 
 	spin_unlock_irq(&dev->power.lock);
 
+	dev_pm_opp_clear_config(gpd_data->opp_token);
 	kfree(gpd_data->td);
 	kfree(gpd_data);
 	dev_pm_put_subsys_data(dev);
@@ -2903,6 +2904,29 @@ static void genpd_dev_pm_sync(struct device *dev)
 	genpd_queue_power_off_work(pd);
 }
 
+static int genpd_set_required_opp_dev(struct device *dev,
+				      struct device *base_dev)
+{
+	struct dev_pm_opp_config config = {
+		.required_dev = dev,
+	};
+	int ret;
+
+	/* Limit support to non-providers for now. */
+	if (of_property_present(base_dev->of_node, "#power-domain-cells"))
+		return 0;
+
+	if (!dev_pm_opp_of_has_required_opp(base_dev))
+		return 0;
+
+	ret = dev_pm_opp_set_config(base_dev, &config);
+	if (ret < 0)
+		return ret;
+
+	dev_gpd_data(dev)->opp_token = ret;
+	return 0;
+}
+
 static int genpd_set_required_opp(struct device *dev, unsigned int index)
 {
 	int ret, pstate;
@@ -2927,7 +2951,8 @@ static int genpd_set_required_opp(struct device *dev, unsigned int index)
 }
 
 static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
-				 unsigned int index, bool power_on)
+				 unsigned int index, unsigned int num_domains,
+				 bool power_on)
 {
 	struct of_phandle_args pd_args;
 	struct generic_pm_domain *pd;
@@ -2959,6 +2984,17 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
 	dev->pm_domain->detach = genpd_dev_pm_detach;
 	dev->pm_domain->sync = genpd_dev_pm_sync;
 
+	/*
+	 * For a single PM domain the index of the required OPP must be zero, so
+	 * let's try to assign a required dev in that case. In the multiple PM
+	 * domains case, we need platform code to specify the index.
+	 */
+	if (num_domains == 1) {
+		ret = genpd_set_required_opp_dev(dev, base_dev);
+		if (ret)
+			goto err;
+	}
+
 	ret = genpd_set_required_opp(dev, index);
 	if (ret)
 		goto err;
@@ -3013,7 +3049,7 @@ int genpd_dev_pm_attach(struct device *dev)
 				       "#power-domain-cells") != 1)
 		return 0;
 
-	return __genpd_dev_pm_attach(dev, dev, 0, true);
+	return __genpd_dev_pm_attach(dev, dev, 0, 1, true);
 }
 EXPORT_SYMBOL_GPL(genpd_dev_pm_attach);
 
@@ -3066,7 +3102,7 @@ struct device *genpd_dev_pm_attach_by_id(struct device *dev,
 	}
 
 	/* Try to attach the device to the PM domain at the specified index. */
-	ret = __genpd_dev_pm_attach(virt_dev, dev, index, false);
+	ret = __genpd_dev_pm_attach(virt_dev, dev, index, num_domains, false);
 	if (ret < 1) {
 		device_unregister(virt_dev);
 		return ret ? ERR_PTR(ret) : NULL;

include/linux/pm_domain.h

@@ -258,6 +258,7 @@ struct generic_pm_domain_data {
 	unsigned int performance_state;
 	unsigned int default_pstate;
 	unsigned int rpm_pstate;
+	unsigned int opp_token;
 	bool hw_mode;
 	void *data;
 };