diff options
Diffstat (limited to 'drivers/base')
| -rw-r--r-- | drivers/base/base.h | 2 | ||||
| -rw-r--r-- | drivers/base/bus.c | 67 |
2 files changed, 56 insertions, 13 deletions
diff --git a/drivers/base/base.h b/drivers/base/base.h index a5b7abc10ff0..21c7d244f8aa 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -27,6 +27,7 @@ * @drivers_autoprobe: gate whether new devices are automatically attached to * registered drivers, or new drivers automatically attach * to existing devices. + * @no_drivers: gate whether drivers can be registered. * @bus: pointer back to the struct bus_type that this structure is associated * with. * @dev_root: Default device to use as the parent. @@ -51,6 +52,7 @@ struct subsys_private { struct klist klist_drivers; struct blocking_notifier_head bus_notifier; unsigned int drivers_autoprobe:1; + unsigned int no_drivers:1; const struct bus_type *bus; struct device *dev_root; diff --git a/drivers/base/bus.c b/drivers/base/bus.c index d17bd91490ee..d89333806a4e 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -738,6 +738,11 @@ int bus_add_driver(struct device_driver *drv) if (!sp) return -EINVAL; + if (sp->no_drivers) { + error = -ENXIO; + goto out_put_bus; + } + /* * Reference in sp is now incremented and will be dropped when * the driver is removed from the bus @@ -930,15 +935,7 @@ static ssize_t bus_uevent_store(const struct bus_type *bus, static struct bus_attribute bus_attr_uevent = __ATTR(uevent, 0200, NULL, bus_uevent_store); -/** - * bus_register - register a driver-core subsystem - * @bus: bus to register - * - * Once we have that, we register the bus with the kobject - * infrastructure, then register the children subsystems it has: - * the devices and drivers that belong to the subsystem. - */ -int bus_register(const struct bus_type *bus) +static int bus_register_internal(const struct bus_type *bus, bool use_drivers) { int retval; struct subsys_private *priv; @@ -960,7 +957,8 @@ int bus_register(const struct bus_type *bus) bus_kobj->kset = bus_kset; bus_kobj->ktype = &bus_ktype; - priv->drivers_autoprobe = 1; + priv->drivers_autoprobe = use_drivers; + priv->no_drivers = !use_drivers; retval = kset_register(&priv->subsys); if (retval) @@ -976,6 +974,10 @@ int bus_register(const struct bus_type *bus) goto bus_devices_fail; } + /* + * Create the drivers kset even if use_drivers is unset to prevent some + * older versions of systemd from failing. + */ priv->drivers_kset = kset_create_and_add("drivers", NULL, bus_kobj); if (!priv->drivers_kset) { retval = -ENOMEM; @@ -989,9 +991,11 @@ int bus_register(const struct bus_type *bus) klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put); klist_init(&priv->klist_drivers, NULL, NULL); - retval = add_probe_files(bus); - if (retval) - goto bus_probe_files_fail; + if (use_drivers) { + retval = add_probe_files(bus); + if (retval) + goto bus_probe_files_fail; + } retval = sysfs_create_groups(bus_kobj, bus->bus_groups); if (retval) @@ -1016,9 +1020,41 @@ out: kfree(priv); return retval; } + +/** + * bus_register - register a driver-core subsystem + * @bus: bus to register + * + * Once we have that, we register the bus with the kobject + * infrastructure, then register the children subsystems it has: + * the devices and drivers that belong to the subsystem. + */ +int bus_register(const struct bus_type *bus) +{ + return bus_register_internal(bus, true); +} EXPORT_SYMBOL_GPL(bus_register); /** + * companion_bus_register - register a companion bus type + * @bus: companion bus to register + * + * A companion bus is a bus without drivers. Devices that belong to it can be + * bound to other devices as their "companions" and represent interfaces that + * can be used by the drivers of those other devices. They may also be used for + * the enumeration of those other devices. + * + * The ACPI bus is a specific example of a companion bus. + * + * Registering a companion bus is like registering a regular bus except that it + * skips the creation of sysfs interfaces related to drivers for @bus. + */ +int companion_bus_register(const struct bus_type *bus) +{ + return bus_register_internal(bus, false); +} + +/** * bus_unregister - remove a bus from the system * @bus: bus. * @@ -1415,6 +1451,11 @@ struct device_driver *driver_find(const char *name, const struct bus_type *bus) if (!sp) return NULL; + if (sp->no_drivers) { + subsys_put(sp); + return NULL; + } + k = kset_find_obj(sp->drivers_kset, name); subsys_put(sp); if (!k) |