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.

Suggested-by: Saravana Kannan <saravanak@google.com>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Tested-by: Hiago De Franco <hiago.franco@toradex.com> # Colibri iMX8X
Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> # TI AM62A,Xilinx ZynqMP ZCU106
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20250701114733.636510-6-ulf.hansson@linaro.org

diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
index 93d71164fc560a684607415e311b605ffd21142d..a41f5f91e87f3d8027fa6193da0c31187379f057 100644 (file)
--- a/drivers/pmdomain/core.c
+++ b/drivers/pmdomain/core.c
@@ -27,6 +27,16 @@
 /* Provides a unique ID for each genpd device */
 static DEFINE_IDA(genpd_ida);
 
+/* The bus for genpd_providers. */
+static const struct bus_type genpd_provider_bus_type = {
+       .name           = "genpd_provider",
+};
+
+/* 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)         \
@@ -2262,6 +2272,8 @@ 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);
@@ -3360,16 +3372,55 @@ 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_sync_state(struct device *dev)
+{
+}
+
+static struct device_driver genpd_provider_drv = {
+       .name = "genpd_provider",
+       .bus = &genpd_provider_bus_type,
+       .probe = genpd_provider_probe,
+       .sync_state = genpd_provider_sync_state,
+       .suppress_bind_attrs = true,
+};
+
 static int __init genpd_bus_init(void)
 {
        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)
-               return ret;
+               goto err_prov_bus;
+
+       ret = driver_register(&genpd_provider_drv);
+       if (ret)
+               goto err_bus;
 
        genpd_bus_registered = true;
        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);