clk: qcom: gdsc: enable optional power domain support

On sm8250 dispcc and videocc registers are powered up by the MMCX power
domain. Currently we use a regulator to enable this domain on demand,
however this has some consequences, as genpd code is not reentrant.

Make gdsc code also use pm_runtime calls to ensure that registers are
accessible during the gdsc_enable/gdsc_disable operations.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210829154757.784699-6-dmitry.baryshkov@linaro.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

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_runtime.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
 #include <linux/reset-controller.h>
@@ -50,6 +51,22 @@ enum gdsc_status {
 	GDSC_ON
 };
 
+static int gdsc_pm_runtime_get(struct gdsc *sc)
+{
+	if (!sc->dev)
+		return 0;
+
+	return pm_runtime_resume_and_get(sc->dev);
+}
+
+static int gdsc_pm_runtime_put(struct gdsc *sc)
+{
+	if (!sc->dev)
+		return 0;
+
+	return pm_runtime_put_sync(sc->dev);
+}
+
 /* Returns 1 if GDSC status is status, 0 if not, and < 0 on error */
 static int gdsc_check_status(struct gdsc *sc, enum gdsc_status status)
 {
@@ -232,9 +249,8 @@ static void gdsc_retain_ff_on(struct gdsc *sc)
 	regmap_update_bits(sc->regmap, sc->gdscr, mask, mask);
 }
 
-static int gdsc_enable(struct generic_pm_domain *domain)
+static int _gdsc_enable(struct gdsc *sc)
 {
-	struct gdsc *sc = domain_to_gdsc(domain);
 	int ret;
 
 	if (sc->pwrsts == PWRSTS_ON)
@@ -290,11 +306,22 @@ static int gdsc_enable(struct generic_pm_domain *domain)
 	return 0;
 }
 
-static int gdsc_disable(struct generic_pm_domain *domain)
+static int gdsc_enable(struct generic_pm_domain *domain)
 {
 	struct gdsc *sc = domain_to_gdsc(domain);
 	int ret;
 
+	ret = gdsc_pm_runtime_get(sc);
+	if (ret)
+		return ret;
+
+	return _gdsc_enable(sc);
+}
+
+static int _gdsc_disable(struct gdsc *sc)
+{
+	int ret;
+
 	if (sc->pwrsts == PWRSTS_ON)
 		return gdsc_assert_reset(sc);
 
@@ -329,6 +356,18 @@ static int gdsc_disable(struct generic_pm_domain *domain)
 	return 0;
 }
 
+static int gdsc_disable(struct generic_pm_domain *domain)
+{
+	struct gdsc *sc = domain_to_gdsc(domain);
+	int ret;
+
+	ret = _gdsc_disable(sc);
+
+	gdsc_pm_runtime_put(sc);
+
+	return ret;
+}
+
 static int gdsc_init(struct gdsc *sc)
 {
 	u32 mask, val;
@@ -443,6 +482,8 @@ int gdsc_register(struct gdsc_desc *desc,
 	for (i = 0; i < num; i++) {
 		if (!scs[i])
 			continue;
+		if (pm_runtime_enabled(dev))
+			scs[i]->dev = dev;
 		scs[i]->regmap = regmap;
 		scs[i]->rcdev = rcdev;
 		ret = gdsc_init(scs[i]);
@@ -457,6 +498,8 @@ int gdsc_register(struct gdsc_desc *desc,
 			continue;
 		if (scs[i]->parent)
 			pm_genpd_add_subdomain(scs[i]->parent, &scs[i]->pd);
+		else if (!IS_ERR_OR_NULL(dev->pm_domain))
+			pm_genpd_add_subdomain(pd_to_genpd(dev->pm_domain), &scs[i]->pd);
 	}
 
 	return of_genpd_add_provider_onecell(dev->of_node, data);
@@ -475,6 +518,8 @@ void gdsc_unregister(struct gdsc_desc *desc)
 			continue;
 		if (scs[i]->parent)
 			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);
 	}
 	of_genpd_del_provider(dev->of_node);
 }

drivers/clk/qcom/gdsc.h

@@ -25,6 +25,7 @@ struct reset_controller_dev;
  * @resets: ids of resets associated with this gdsc
  * @reset_count: number of @resets
  * @rcdev: reset controller
+ * @dev: the device holding the GDSC, used for pm_runtime calls
  */
 struct gdsc {
 	struct generic_pm_domain	pd;
@@ -58,6 +59,7 @@ struct gdsc {
 
 	const char 			*supply;
 	struct regulator		*rsupply;
+	struct device			*dev;
 };
 
 struct gdsc_desc {