linux-kernel - [PATCH v4 3/3] clk: qcom: Support attaching GDSCs to multiple parents

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Message-Id: <20241127-b4-linux-next-24-11-18-clock-multiple-power-domains-v4-3-4348d40cb635@linaro.org>
Date: Wed, 27 Nov 2024 15:53:56 +0000
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Bjorn Andersson <andersson@...nel.org>, 
 Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Subject: [PATCH v4 3/3] clk: qcom: Support attaching GDSCs to multiple
 parents

When a clock-controller has multiple power-domains we need to attach
parent GDSCs in that clock-controller as subdomains of each of the
power-domains.

Testing on the x1e80100 reference shows that both power-domains need to be
switched on for the GDSCs in the clock-controller to work. Some open
questions remain.

1. Should there be a hirearchy of power-domains in the clock-controller.
2. If there should be no hirearchy should the parent GDSC inside the
   clock-controller attach to each power-domain in the clock-controller.
3. If there are multiple parent GDSCs in a clock-controller do we attach
   those top-level GDSCs to each controller power-domain.
4. Finally should performance-states be applied equally across those
   power-domains.

It may be if we see more clock-controllers with multiple power-domains that
some mixture of these questions will need to be implemented for specific
hardware. Right now the approach taken here is to attach the
clock-controller GDSC parent to each clock-controller power-domain.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
---
 drivers/clk/qcom/common.c |  1 +
 drivers/clk/qcom/gdsc.c   | 35 +++++++++++++++++++++++++++++++++++
 drivers/clk/qcom/gdsc.h   |  1 +
 3 files changed, 37 insertions(+)

diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c
index 7727295c57c8f6672d46d2380e1ff5ec2ac68d42..58a8397eefe51da237a4285d4e7cee967e19948f 100644
--- a/drivers/clk/qcom/common.c
+++ b/drivers/clk/qcom/common.c
@@ -338,6 +338,7 @@ int qcom_cc_really_probe(struct device *dev,
 		scd->dev = dev;
 		scd->scs = desc->gdscs;
 		scd->num = desc->num_gdscs;
+		scd->pd_list = cc->pd_list;
 		ret = gdsc_register(scd, &reset->rcdev, regmap);
 		if (ret)
 			return ret;
diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
index 4fc6f957d0b846cc90e50ef243f23a7a27e66899..cb4afa6d584899f3dafa380d5e01be6de9711737 100644
--- a/drivers/clk/qcom/gdsc.c
+++ b/drivers/clk/qcom/gdsc.c
@@ -506,6 +506,36 @@ static int gdsc_init(struct gdsc *sc)
 	return ret;
 }
 
+static int gdsc_add_subdomain_list(struct dev_pm_domain_list *pd_list,
+				   struct generic_pm_domain *subdomain)
+{
+	int i, ret;
+
+	for (i = 0; i < pd_list->num_pds; i++) {
+		struct device *dev = pd_list->pd_devs[i];
+		struct generic_pm_domain *genpd = pd_to_genpd(dev->pm_domain);
+
+		ret = pm_genpd_add_subdomain(genpd, subdomain);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static void gdsc_remove_subdomain_list(struct dev_pm_domain_list *pd_list,
+				       struct generic_pm_domain *subdomain)
+{
+	int i;
+
+	for (i = 0; i < pd_list->num_pds; i++) {
+		struct device *dev = pd_list->pd_devs[i];
+		struct generic_pm_domain *genpd = pd_to_genpd(dev->pm_domain);
+
+		pm_genpd_remove_subdomain(genpd, subdomain);
+	}
+}
+
 int gdsc_register(struct gdsc_desc *desc,
 		  struct reset_controller_dev *rcdev, struct regmap *regmap)
 {
@@ -558,6 +588,9 @@ int gdsc_register(struct gdsc_desc *desc,
 			ret = pm_genpd_add_subdomain(scs[i]->parent, &scs[i]->pd);
 		else if (!IS_ERR_OR_NULL(dev->pm_domain))
 			ret = pm_genpd_add_subdomain(pd_to_genpd(dev->pm_domain), &scs[i]->pd);
+		else if (desc->pd_list)
+			ret = gdsc_add_subdomain_list(desc->pd_list, &scs[i]->pd);
+
 		if (ret)
 			return ret;
 	}
@@ -580,6 +613,8 @@ void gdsc_unregister(struct gdsc_desc *desc)
 			pm_genpd_remove_subdomain(scs[i]->parent, &scs[i]->pd);
 		else if (!IS_ERR_OR_NULL(dev->pm_domain))
 			pm_genpd_remove_subdomain(pd_to_genpd(dev->pm_domain), &scs[i]->pd);
+		else if (desc->pd_list)
+			gdsc_remove_subdomain_list(desc->pd_list, &scs[i]->pd);
 	}
 	of_genpd_del_provider(dev->of_node);
 }
diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
index 1e2779b823d1c8ca077c9b4cd0a0dbdf5f9457ef..dd843e86c05b2f30e6d9e978681580016333839d 100644
--- a/drivers/clk/qcom/gdsc.h
+++ b/drivers/clk/qcom/gdsc.h
@@ -80,6 +80,7 @@ struct gdsc_desc {
 	struct device *dev;
 	struct gdsc **scs;
 	size_t num;
+	struct dev_pm_domain_list *pd_list;
 };
 
 #ifdef CONFIG_QCOM_GDSC

-- 
2.45.2