linux-kernel - [PATCH 04/11] pmdomain: core: Add a bus and a driver for genpd providers

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Message-ID: <20250417142513.312939-5-ulf.hansson@linaro.org>
Date: Thu, 17 Apr 2025 16:25:02 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Saravana Kannan <saravanak@...gle.com>,
	Stephen Boyd <sboyd@...nel.org>,
	linux-pm@...r.kernel.org
Cc: "Rafael J . Wysocki" <rafael@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Michael Grzeschik <m.grzeschik@...gutronix.de>,
	Bjorn Andersson <andersson@...nel.org>,
	Abel Vesa <abel.vesa@...aro.org>,
	Devarsh Thakkar <devarsht@...v0571a.ent.ti.com>,
	Peng Fan <peng.fan@....nxp.com>,
	Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
	Johan Hovold <johan@...nel.org>,
	Maulik Shah <maulik.shah@....qualcomm.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 04/11] pmdomain: core: Add a bus and a driver for genpd providers

When we create a genpd via pm_genpd_init() we are initializing a
corresponding struct device for it, but we don't add the device to any
bus_type. It has not really been needed as the device is used as cookie to
help us manage OPP tables.

However, to prepare to make better use of the device let's add a new genpd
provider bus_type and a corresponding genpd provider driver. Subsequent
changes will make use of this.

Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
---
 drivers/pmdomain/core.c | 89 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 88 insertions(+), 1 deletion(-)

diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
index 035b65563947..da51a61a974c 100644
--- a/drivers/pmdomain/core.c
+++ b/drivers/pmdomain/core.c
@@ -27,6 +27,11 @@
 /* Provides a unique ID for each genpd device */
 static DEFINE_IDA(genpd_ida);
 
+/* The parent for genpd_provider devices. */
+static struct device genpd_provider_bus = {
+	.init_name = "genpd_provider",
+};
+
 #define GENPD_RETRY_MAX_MS	250		/* Approximate */
 
 #define GENPD_DEV_CALLBACK(genpd, type, callback, dev)		\
@@ -44,6 +49,14 @@ static DEFINE_IDA(genpd_ida);
 static LIST_HEAD(gpd_list);
 static DEFINE_MUTEX(gpd_list_lock);
 
+#define to_genpd_provider_drv(d) container_of(d, struct genpd_provider_drv, drv)
+
+struct genpd_provider_drv {
+	struct device_driver drv;
+	int (*probe)(struct device *dev);
+	void (*remove)(struct device *dev);
+};
+
 struct genpd_lock_ops {
 	void (*lock)(struct generic_pm_domain *genpd);
 	void (*lock_nested)(struct generic_pm_domain *genpd, int depth);
@@ -2225,6 +2238,26 @@ static int genpd_set_default_power_state(struct generic_pm_domain *genpd)
 	return 0;
 }
 
+static int genpd_provider_bus_probe(struct device *dev)
+{
+	struct genpd_provider_drv *drv = to_genpd_provider_drv(dev->driver);
+
+	return drv->probe(dev);
+}
+
+static void genpd_provider_bus_remove(struct device *dev)
+{
+	struct genpd_provider_drv *drv = to_genpd_provider_drv(dev->driver);
+
+	drv->remove(dev);
+}
+
+static const struct bus_type genpd_provider_bus_type = {
+	.name		= "genpd_provider",
+	.probe		= genpd_provider_bus_probe,
+	.remove		= genpd_provider_bus_remove,
+};
+
 static void genpd_provider_release(struct device *dev)
 {
 	/* nothing to be done here */
@@ -2262,6 +2295,8 @@ static int genpd_alloc_data(struct generic_pm_domain *genpd)
 	genpd->gd = gd;
 	device_initialize(&genpd->dev);
 	genpd->dev.release = genpd_provider_release;
+	genpd->dev.bus = &genpd_provider_bus_type;
+	genpd->dev.parent = &genpd_provider_bus;
 
 	if (!genpd_is_dev_name_fw(genpd)) {
 		dev_set_name(&genpd->dev, "%s", genpd->name);
@@ -3355,9 +3390,61 @@ int of_genpd_parse_idle_states(struct device_node *dn,
 }
 EXPORT_SYMBOL_GPL(of_genpd_parse_idle_states);
 
+static int genpd_provider_probe(struct device *dev)
+{
+	return 0;
+}
+
+static void genpd_provider_remove(struct device *dev)
+{
+}
+
+static void genpd_provider_sync_state(struct device *dev)
+{
+}
+
+static struct genpd_provider_drv genpd_provider_drv = {
+	.drv = {
+		.name = "genpd_provider",
+		.bus = &genpd_provider_bus_type,
+		.sync_state = genpd_provider_sync_state,
+		.suppress_bind_attrs = true,
+	},
+	.probe = genpd_provider_probe,
+	.remove = genpd_provider_remove,
+};
+
 static int __init genpd_bus_init(void)
 {
-	return bus_register(&genpd_bus_type);
+	int ret;
+
+	ret = device_register(&genpd_provider_bus);
+	if (ret) {
+		put_device(&genpd_provider_bus);
+		return ret;
+	}
+
+	ret = bus_register(&genpd_provider_bus_type);
+	if (ret)
+		goto err_dev;
+
+	ret = bus_register(&genpd_bus_type);
+	if (ret)
+		goto err_prov_bus;
+
+	ret = driver_register(&genpd_provider_drv.drv);
+	if (ret)
+		goto err_bus;
+
+	return 0;
+
+err_bus:
+	bus_unregister(&genpd_bus_type);
+err_prov_bus:
+	bus_unregister(&genpd_provider_bus_type);
+err_dev:
+	device_unregister(&genpd_provider_bus);
+	return ret;
 }
 core_initcall(genpd_bus_init);
 
-- 
2.43.0