Merge branch 'experimental/acpi-driver-work' into bleeding-edge * experimental/acpi-driver-work: ACPI: Documentation: Remove driver-api/acpi/acpi-drivers.rst ACPI: scan: Set power.no_pm for all struct acpi_device objects driver core/ACPI: Make it possible to register a fake bus type ACPI: bus: Eliminate struct acpi_driver
diff --git a/Documentation/driver-api/acpi/acpi-drivers.rst b/Documentation/driver-api/acpi/acpi-drivers.rst deleted file mode 100644 index 376b6d8..0000000 --- a/Documentation/driver-api/acpi/acpi-drivers.rst +++ /dev/null
@@ -1,80 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0 -.. include:: <isonum.txt> - -========================================= -Why using ACPI drivers is not a good idea -========================================= - -:Copyright: |copy| 2026, Intel Corporation - -:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com> - -Even though binding drivers directly to struct acpi_device objects, also -referred to as "ACPI device nodes", allows basic functionality to be provided -at least in some cases, there are problems with it, related to general -consistency, sysfs layout, power management operation ordering, and code -cleanliness. - -First of all, ACPI device nodes represent firmware entities rather than -hardware and in many cases they provide auxiliary information on devices -enumerated independently (like PCI devices or CPUs). It is therefore generally -questionable to assign resources to them because the entities represented by -them do not decode addresses in the memory or I/O address spaces and do not -generate interrupts or similar (all of that is done by hardware). - -Second, as a general rule, a struct acpi_device can only be a parent of another -struct acpi_device. If that is not the case, the location of the child device -in the device hierarchy is at least confusing and it may not be straightforward -to identify the piece of hardware providing functionality represented by it. -However, binding a driver directly to an ACPI device node may cause that to -happen if the given driver registers input devices or wakeup sources under it, -for example. - -Next, using system suspend and resume callbacks directly on ACPI device nodes -is also questionable because it may cause ordering problems to appear. Namely, -ACPI device nodes are registered before enumerating hardware corresponding to -them and they land on the PM list in front of the majority of other device -objects. Consequently, the execution ordering of their PM callbacks may be -different from what is generally expected. Also, in general, dependencies -returned by _DEP objects do not affect ACPI device nodes themselves, but the -"physical" devices associated with them, which potentially is one more source -of inconsistency related to treating ACPI device nodes as "real" device -representation. - -All of the above means that binding drivers to ACPI device nodes should -generally be avoided and so struct acpi_driver objects should not be used. - -Moreover, a device ID is necessary to bind a driver directly to an ACPI device -node, but device IDs are not generally associated with all of them. Some of -them contain alternative information allowing the corresponding pieces of -hardware to be identified, for example represented by an _ADR object return -value, and device IDs are not used in those cases. In consequence, confusingly -enough, binding an ACPI driver to an ACPI device node may even be impossible. - -When that happens, the piece of hardware corresponding to the given ACPI device -node is represented by another device object, like a struct pci_dev, and the -ACPI device node is the "ACPI companion" of that device, accessible through its -fwnode pointer used by the ACPI_COMPANION() macro. The ACPI companion holds -additional information on the device configuration and possibly some "recipes" -on device manipulation in the form of AML (ACPI Machine Language) bytecode -provided by the platform firmware. Thus the role of the ACPI device node is -similar to the role of a struct device_node on a system where Device Tree is -used for platform description. - -For consistency, this approach has been extended to the cases in which ACPI -device IDs are used. Namely, in those cases, an additional device object is -created to represent the piece of hardware corresponding to a given ACPI device -node. By default, it is a platform device, but it may also be a PNP device, a -CPU device, or another type of device, depending on what the given piece of -hardware actually is. There are even cases in which multiple devices are -"backed" or "accompanied" by one ACPI device node (e.g. ACPI device nodes -corresponding to GPUs that may provide firmware interfaces for backlight -brightness control in addition to GPU configuration information). - -This means that it really should never be necessary to bind a driver directly to -an ACPI device node because there is a "proper" device object representing the -corresponding piece of hardware that can be bound to by a "proper" driver using -the given ACPI device node as the device's ACPI companion. Thus, in principle, -there is no reason to use ACPI drivers and if they all were replaced with other -driver types (for example, platform drivers), some code could be dropped and -some complexity would go away.
diff --git a/Documentation/driver-api/acpi/index.rst b/Documentation/driver-api/acpi/index.rst index 2b10d83..ace0008 100644 --- a/Documentation/driver-api/acpi/index.rst +++ b/Documentation/driver-api/acpi/index.rst
@@ -7,4 +7,3 @@ linuxized-acpica scan_handlers - acpi-drivers
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c index b0e7181a..448e4c6 100644 --- a/drivers/acpi/bus.c +++ b/drivers/acpi/bus.c
@@ -620,41 +620,6 @@ static void acpi_bus_notify(acpi_handle handle, u32 type, void *data) acpi_evaluate_ost(handle, type, ACPI_OST_SC_NON_SPECIFIC_FAILURE, NULL); } -static void acpi_notify_device(acpi_handle handle, u32 event, void *data) -{ - struct acpi_device *device = data; - struct acpi_driver *acpi_drv = to_acpi_driver(device->dev.driver); - - acpi_drv->ops.notify(device, event); -} - -static int acpi_device_install_notify_handler(struct acpi_device *device, - struct acpi_driver *acpi_drv) -{ - u32 type = acpi_drv->flags & ACPI_DRIVER_ALL_NOTIFY_EVENTS ? - ACPI_ALL_NOTIFY : ACPI_DEVICE_NOTIFY; - acpi_status status; - - status = acpi_install_notify_handler(device->handle, type, - acpi_notify_device, device); - if (ACPI_FAILURE(status)) - return -EINVAL; - - return 0; -} - -static void acpi_device_remove_notify_handler(struct acpi_device *device, - struct acpi_driver *acpi_drv) -{ - u32 type = acpi_drv->flags & ACPI_DRIVER_ALL_NOTIFY_EVENTS ? - ACPI_ALL_NOTIFY : ACPI_DEVICE_NOTIFY; - - acpi_remove_notify_handler(device->handle, type, - acpi_notify_device); - - acpi_os_wait_events_complete(); -} - int acpi_dev_install_notify_handler(struct acpi_device *adev, u32 handler_type, acpi_notify_handler handler, void *context) @@ -1122,123 +1087,16 @@ bool acpi_driver_match_device(struct device *dev, EXPORT_SYMBOL_GPL(acpi_driver_match_device); /* -------------------------------------------------------------------------- - ACPI Driver Management - -------------------------------------------------------------------------- */ - -/** - * __acpi_bus_register_driver - register a driver with the ACPI bus - * @driver: driver being registered - * @owner: owning module/driver - * - * Registers a driver with the ACPI bus. Searches the namespace for all - * devices that match the driver's criteria and binds. Returns zero for - * success or a negative error status for failure. - */ -int __acpi_bus_register_driver(struct acpi_driver *driver, struct module *owner) -{ - if (acpi_disabled) - return -ENODEV; - driver->drv.name = driver->name; - driver->drv.bus = &acpi_bus_type; - driver->drv.owner = owner; - - return driver_register(&driver->drv); -} - -EXPORT_SYMBOL(__acpi_bus_register_driver); - -/** - * acpi_bus_unregister_driver - unregisters a driver with the ACPI bus - * @driver: driver to unregister - * - * Unregisters a driver with the ACPI bus. Searches the namespace for all - * devices that match the driver's criteria and unbinds. - */ -void acpi_bus_unregister_driver(struct acpi_driver *driver) -{ - driver_unregister(&driver->drv); -} - -EXPORT_SYMBOL(acpi_bus_unregister_driver); - -/* -------------------------------------------------------------------------- ACPI Bus operations -------------------------------------------------------------------------- */ -static int acpi_bus_match(struct device *dev, const struct device_driver *drv) -{ - struct acpi_device *acpi_dev = to_acpi_device(dev); - const struct acpi_driver *acpi_drv = to_acpi_driver(drv); - - return acpi_dev->flags.match_driver - && !acpi_match_device_ids(acpi_dev, acpi_drv->ids); -} - static int acpi_device_uevent(const struct device *dev, struct kobj_uevent_env *env) { return __acpi_device_uevent_modalias(to_acpi_device(dev), env); } -static int acpi_device_probe(struct device *dev) -{ - struct acpi_device *acpi_dev = to_acpi_device(dev); - struct acpi_driver *acpi_drv = to_acpi_driver(dev->driver); - int ret; - - if (acpi_dev->handler && !acpi_is_pnp_device(acpi_dev)) - return -EINVAL; - - if (!acpi_drv->ops.add) - return -ENOSYS; - - ret = acpi_drv->ops.add(acpi_dev); - if (ret) { - acpi_dev->driver_data = NULL; - return ret; - } - - pr_debug("Driver [%s] successfully bound to device [%s]\n", - acpi_drv->name, acpi_dev->pnp.bus_id); - - if (acpi_drv->ops.notify) { - ret = acpi_device_install_notify_handler(acpi_dev, acpi_drv); - if (ret) { - if (acpi_drv->ops.remove) - acpi_drv->ops.remove(acpi_dev); - - acpi_dev->driver_data = NULL; - return ret; - } - } - - pr_debug("Found driver [%s] for device [%s]\n", acpi_drv->name, - acpi_dev->pnp.bus_id); - - get_device(dev); - return 0; -} - -static void acpi_device_remove(struct device *dev) -{ - struct acpi_device *acpi_dev = to_acpi_device(dev); - struct acpi_driver *acpi_drv = to_acpi_driver(dev->driver); - - if (acpi_drv->ops.notify) - acpi_device_remove_notify_handler(acpi_dev, acpi_drv); - - if (acpi_drv->ops.remove) - acpi_drv->ops.remove(acpi_dev); - - acpi_dev->driver_data = NULL; - - put_device(dev); -} - const struct bus_type acpi_bus_type = { .name = "acpi", - .match = acpi_bus_match, - .probe = acpi_device_probe, - .remove = acpi_device_remove, .uevent = acpi_device_uevent, }; @@ -1542,7 +1400,7 @@ static int __init acpi_bus_init(void) */ acpi_root_dir = proc_mkdir(ACPI_BUS_FILE_ROOT, NULL); - result = bus_register(&acpi_bus_type); + result = bus_register_fake(&acpi_bus_type); if (!result) return 0;
diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c index d4131c1..23a4e20 100644 --- a/drivers/acpi/power.c +++ b/drivers/acpi/power.c
@@ -954,7 +954,6 @@ struct acpi_device *acpi_add_power_resource(acpi_handle handle) INIT_LIST_HEAD(&resource->list_node); INIT_LIST_HEAD(&resource->dependents); device->power.state = ACPI_STATE_UNKNOWN; - device->flags.match_driver = true; /* Evaluate the object to get the system level and resource order. */ status = acpi_evaluate_object(handle, NULL, NULL, &buffer);
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index 075798d..e5de106 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c
@@ -273,13 +273,9 @@ static int acpi_scan_check_and_detach(struct acpi_device *adev, void *p) } } - adev->flags.match_driver = false; - if (handler) { - if (handler->detach) - handler->detach(adev); - } else { - device_release_driver(&adev->dev); - } + if (handler && handler->detach) + handler->detach(adev); + /* * Most likely, the device is going away, so put it into D3cold before * that. @@ -1815,13 +1811,13 @@ void acpi_init_device_object(struct acpi_device *device, acpi_handle handle, device->dev.release = release; device->dev.bus = &acpi_bus_type; device->dev.groups = acpi_groups; + device_set_pm_not_required(&device->dev); fwnode_init(&device->fwnode, &acpi_device_fwnode_ops); acpi_set_device_status(device, ACPI_STA_DEFAULT); acpi_device_get_busid(device); acpi_set_pnp_ids(handle, &device->pnp, type); acpi_init_properties(device); acpi_bus_get_flags(device); - device->flags.match_driver = false; device->flags.initialized = true; device->flags.enumeration_by_parent = acpi_device_enumeration_by_parent(device); @@ -2375,16 +2371,11 @@ static int acpi_bus_attach(struct acpi_device *device, void *first_pass) if (ret < 0) return 0; - device->flags.match_driver = true; if (ret > 0 && !device->flags.enumeration_by_parent) { acpi_device_set_enumerated(device); goto ok; } - ret = device_attach(&device->dev); - if (ret < 0) - return 0; - if (device->pnp.type.platform_id || device->pnp.type.backlight || device->flags.enumeration_by_parent) acpi_default_enumeration(device);
diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 8b6722f..2bd3c9c 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c
@@ -728,7 +728,7 @@ int bus_add_driver(struct device_driver *drv) struct driver_private *priv; int error = 0; - if (!sp) + if (!sp || !sp->drivers_kset) return -EINVAL; /* @@ -923,15 +923,7 @@ 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 has_drivers) { int retval; struct subsys_private *priv; @@ -953,7 +945,7 @@ 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 = has_drivers; retval = kset_register(&priv->subsys); if (retval) @@ -969,10 +961,12 @@ int bus_register(const struct bus_type *bus) goto bus_devices_fail; } - priv->drivers_kset = kset_create_and_add("drivers", NULL, bus_kobj); - if (!priv->drivers_kset) { - retval = -ENOMEM; - goto bus_drivers_fail; + if (has_drivers) { + priv->drivers_kset = kset_create_and_add("drivers", NULL, bus_kobj); + if (!priv->drivers_kset) { + retval = -ENOMEM; + goto bus_drivers_fail; + } } INIT_LIST_HEAD(&priv->interfaces); @@ -982,9 +976,11 @@ 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 (has_drivers) { + retval = add_probe_files(bus); + if (retval) + goto bus_probe_files_fail; + } retval = sysfs_create_groups(bus_kobj, bus->bus_groups); if (retval) @@ -1009,6 +1005,28 @@ int bus_register(const struct bus_type *bus) kfree(priv); return retval; } + +/** + * bus_register_fake - register a "fake" bus type without drivers + * @bus: bus to register + */ +int bus_register_fake(const struct bus_type *bus) +{ + return bus_register_internal(bus, false); +} + +/** + * 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); /** @@ -1405,7 +1423,7 @@ struct device_driver *driver_find(const char *name, const struct bus_type *bus) struct kobject *k; struct driver_private *priv; - if (!sp) + if (!sp || !sp->drivers_kset) return NULL; k = kset_find_obj(sp->drivers_kset, name);
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h index 7e57f96..46b12c2 100644 --- a/include/acpi/acpi_bus.h +++ b/include/acpi/acpi_bus.h
@@ -108,7 +108,6 @@ enum acpi_bus_device_type { ACPI_BUS_DEVICE_TYPE_COUNT }; -struct acpi_driver; struct acpi_device; /* @@ -159,32 +158,6 @@ struct acpi_hotplug_context { }; /* - * ACPI Driver - * ----------- - */ - -typedef int (*acpi_op_add) (struct acpi_device * device); -typedef void (*acpi_op_remove) (struct acpi_device *device); -typedef void (*acpi_op_notify) (struct acpi_device * device, u32 event); - -struct acpi_device_ops { - acpi_op_add add; - acpi_op_remove remove; - acpi_op_notify notify; -}; - -#define ACPI_DRIVER_ALL_NOTIFY_EVENTS 0x1 /* system AND device events */ - -struct acpi_driver { - char name[80]; - char class[80]; - const struct acpi_device_id *ids; /* Supported Hardware IDs */ - unsigned int flags; - struct acpi_device_ops ops; - struct device_driver drv; -}; - -/* * ACPI Device * ----------- */ @@ -207,7 +180,6 @@ struct acpi_device_flags { u32 removable:1; u32 ejectable:1; u32 power_manageable:1; - u32 match_driver:1; u32 initialized:1; u32 visited:1; u32 hotplug_notify:1; @@ -217,7 +189,7 @@ struct acpi_device_flags { u32 cca_seen:1; u32 enumeration_by_parent:1; u32 honor_deps:1; - u32 reserved:18; + u32 reserved:19; }; /* File System */ @@ -566,7 +538,6 @@ static inline void *acpi_driver_data(struct acpi_device *d) } #define to_acpi_device(d) container_of(d, struct acpi_device, dev) -#define to_acpi_driver(d) container_of_const(d, struct acpi_driver, drv) static inline struct acpi_device *acpi_dev_parent(struct acpi_device *adev) { @@ -672,13 +643,6 @@ void acpi_scan_lock_release(void); void acpi_lock_hp_context(void); void acpi_unlock_hp_context(void); int acpi_scan_add_handler(struct acpi_scan_handler *handler); -/* - * use a macro to avoid include chaining to get THIS_MODULE - */ -#define acpi_bus_register_driver(drv) \ - __acpi_bus_register_driver(drv, THIS_MODULE) -int __acpi_bus_register_driver(struct acpi_driver *driver, struct module *owner); -void acpi_bus_unregister_driver(struct acpi_driver *driver); int acpi_bus_scan(acpi_handle handle); void acpi_bus_trim(struct acpi_device *start); acpi_status acpi_bus_get_ejd(acpi_handle handle, acpi_handle * ejd); @@ -692,18 +656,6 @@ static inline bool acpi_device_enumerated(struct acpi_device *adev) return adev && adev->flags.initialized && adev->flags.visited; } -/** - * module_acpi_driver(acpi_driver) - Helper macro for registering an ACPI driver - * @__acpi_driver: acpi_driver struct - * - * Helper macro for ACPI drivers which do not do anything special in module - * init/exit. This eliminates a lot of boilerplate. Each module may only - * use this macro once, and calling it replaces module_init() and module_exit() - */ -#define module_acpi_driver(__acpi_driver) \ - module_driver(__acpi_driver, acpi_bus_register_driver, \ - acpi_bus_unregister_driver) - /* * Bind physical devices with ACPI devices */
diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h index c1b463c..c98ebca 100644 --- a/include/linux/device/bus.h +++ b/include/linux/device/bus.h
@@ -113,6 +113,7 @@ struct bus_type { bool need_parent_lock; }; +int __must_check bus_register_fake(const struct bus_type *bus); int __must_check bus_register(const struct bus_type *bus); void bus_unregister(const struct bus_type *bus);