[RFC 2/4] clk: qcom: gdsc: enable external switchable power domain

[Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>]

Some GDSCs (SM8250's MDSS_GDSC for example) need switchable power domain
to be on to be able to access hardware registers. Use dev_pm/opp to
enable corresponding power domain.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
---
 drivers/clk/qcom/gdsc.c | 56 ++++++++++++++++++++++++++++++++++++++---
 drivers/clk/qcom/gdsc.h |  5 ++++
 2 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
index bfc4ac02f9ea..a522e062a79a 100644
--- a/drivers/clk/qcom/gdsc.c
+++ b/drivers/clk/qcom/gdsc.c
@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/ktime.h>
 #include <linux/pm_domain.h>
+#include <linux/pm_opp.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
 #include <linux/reset-controller.h>
@@ -110,13 +111,31 @@ static int gdsc_poll_status(struct gdsc *sc, enum gdsc_status status)
 	return -ETIMEDOUT;
 }
 
+int gdsc_toggle_on(struct gdsc *sc)
+{
+	if (sc->rsupply)
+		return regulator_enable(sc->rsupply);
+	if (sc->pd_dev)
+		return dev_pm_genpd_set_performance_state(sc->pd_dev, sc->pd_opp);
+	return 0;
+}
+
+int gdsc_toggle_off(struct gdsc *sc)
+{
+	if (sc->pd_dev)
+		return dev_pm_genpd_set_performance_state(sc->pd_dev, 0);
+	if (sc->rsupply)
+		return regulator_disable(sc->rsupply);
+	return 0;
+}
+
 static int gdsc_toggle_logic(struct gdsc *sc, enum gdsc_status status)
 {
 	int ret;
 	u32 val = (status == GDSC_ON) ? 0 : SW_COLLAPSE_MASK;
 
-	if (status == GDSC_ON && sc->rsupply) {
-		ret = regulator_enable(sc->rsupply);
+	if (status == GDSC_ON) {
+		ret = gdsc_toggle_on(sc);
 		if (ret < 0)
 			return ret;
 	}
@@ -153,8 +172,8 @@ static int gdsc_toggle_logic(struct gdsc *sc, enum gdsc_status status)
 	ret = gdsc_poll_status(sc, status);
 	WARN(ret, "%s status stuck at 'o%s'", sc->pd.name, status ? "ff" : "n");
 
-	if (!ret && status == GDSC_OFF && sc->rsupply) {
-		ret = regulator_disable(sc->rsupply);
+	if (!ret && status == GDSC_OFF) {
+		ret = gdsc_toggle_off(sc);
 		if (ret < 0)
 			return ret;
 	}
@@ -407,6 +426,27 @@ int gdsc_register(struct gdsc_desc *desc,
 			return PTR_ERR(scs[i]->rsupply);
 	}
 
+	for (i = 0; i < num; i++) {
+		if (!scs[i] || !scs[i]->domain)
+			continue;
+
+		scs[i]->pd_opp = of_get_required_opp_performance_state(dev->of_node, scs[i]->perf_idx);
+		if (scs[i]->pd_opp < 0)
+			return scs[i]->pd_opp;
+
+		scs[i]->pd_dev = dev_pm_domain_attach_by_name(dev, scs[i]->domain);
+		if (IS_ERR(scs[i]->pd_dev)) {
+			ret = PTR_ERR(scs[i]->pd_dev);
+			/* Single domain has been already attached, so reuse dev */
+			if (ret == -EEXIST) {
+				scs[i]->pd_dev = dev;
+			} else {
+				scs[i]->pd_dev = NULL;
+				goto pm_detach;
+			}
+		}
+	}
+
 	data->num_domains = num;
 	for (i = 0; i < num; i++) {
 		if (!scs[i])
@@ -428,6 +468,12 @@ int gdsc_register(struct gdsc_desc *desc,
 	}
 
 	return of_genpd_add_provider_onecell(dev->of_node, data);
+
+pm_detach:
+	for (i = 0; i < num; i++)
+		if (scs[i]->pd_dev)
+			dev_pm_domain_detach(scs[i]->pd_dev, false);
+	return ret;
 }
 
 void gdsc_unregister(struct gdsc_desc *desc)
@@ -443,6 +489,8 @@ void gdsc_unregister(struct gdsc_desc *desc)
 			continue;
 		if (scs[i]->parent)
 			pm_genpd_remove_subdomain(scs[i]->parent, &scs[i]->pd);
+		if (scs[i]->pd_dev && scs[i]->pd_dev != dev)
+			dev_pm_domain_detach(scs[i]->pd_dev, true);
 	}
 	of_genpd_del_provider(dev->of_node);
 }
diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
index bd537438c793..d58575f8f25f 100644
--- a/drivers/clk/qcom/gdsc.h
+++ b/drivers/clk/qcom/gdsc.h
@@ -57,6 +57,11 @@ struct gdsc {
 
 	const char 			*supply;
 	struct regulator		*rsupply;
+
+	const char			*domain;
+	unsigned int			perf_idx;
+	struct device			*pd_dev;
+	int				pd_opp;
 };
 
 struct gdsc_desc {
-- 
2.28.0