/* * bus.c - bus driver management * * Copyright (c) 2002-3 Patrick Mochel * Copyright (c) 2002-3 Open Source Development Labs * * This file is released under the GPLv2 * */ #include <linux/config.h> #include <linux/device.h> #include <linux/module.h> #include <linux/errno.h> #include <linux/init.h> #include <linux/string.h> #include "base.h" #include "power/power.h" #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr) #define to_bus(obj) container_of(obj, struct bus_type, subsys.kset.kobj) /* * sysfs bindings for drivers */ #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr) #define to_driver(obj) container_of(obj, struct device_driver, kobj) static ssize_t drv_attr_show(struct kobject * kobj, struct attribute * attr, char * buf) { struct driver_attribute * drv_attr = to_drv_attr(attr); struct device_driver * drv = to_driver(kobj); ssize_t ret = -EIO; if (drv_attr->show) ret = drv_attr->show(drv, buf); return ret; } static ssize_t drv_attr_store(struct kobject * kobj, struct attribute * attr, const char * buf, size_t count) { struct driver_attribute * drv_attr = to_drv_attr(attr); struct device_driver * drv = to_driver(kobj); ssize_t ret = -EIO; if (drv_attr->store) ret = drv_attr->store(drv, buf, count); return ret; } static struct sysfs_ops driver_sysfs_ops = { .show = drv_attr_show, .store = drv_attr_store, }; static void driver_release(struct kobject * kobj) { struct device_driver * drv = to_driver(kobj); complete(&drv->unloaded); } static struct kobj_type ktype_driver = { .sysfs_ops = &driver_sysfs_ops, .release = driver_release, }; /* * sysfs bindings for buses */ static ssize_t bus_attr_show(struct kobject * kobj, struct attribute * attr, char * buf) { struct bus_attribute * bus_attr = to_bus_attr(attr); struct bus_type * bus = to_bus(kobj); ssize_t ret = 0; if (bus_attr->show) ret = bus_attr->show(bus, buf); return ret; } static ssize_t bus_attr_store(struct kobject * kobj, struct attribute * attr, const char * buf, size_t count) { struct bus_attribute * bus_attr = to_bus_attr(attr); struct bus_type * bus = to_bus(kobj); ssize_t ret = 0; if (bus_attr->store) ret = bus_attr->store(bus, buf, count); return ret; } static struct sysfs_ops bus_sysfs_ops = { .show = bus_attr_show, .store = bus_attr_store, }; int bus_create_file(struct bus_type * bus, struct bus_attribute * attr) { int error; if (get_bus(bus)) { error = sysfs_create_file(&bus->subsys.kset.kobj, &attr->attr); put_bus(bus); } else error = -EINVAL; return error; } void bus_remove_file(struct bus_type * bus, struct bus_attribute * attr) { if (get_bus(bus)) { sysfs_remove_file(&bus->subsys.kset.kobj, &attr->attr); put_bus(bus); } } static struct kobj_type ktype_bus = { .sysfs_ops = &bus_sysfs_ops, }; decl_subsys(bus, &ktype_bus, NULL); #ifdef CONFIG_HOTPLUG /* Manually detach a device from its associated driver. */ static int driver_helper(struct device *dev, void *data) { const char *name = data; if (strcmp(name, dev->bus_id) == 0) return 1; return 0; } static ssize_t driver_unbind(struct device_driver *drv, const char *buf, size_t count) { struct bus_type *bus = get_bus(drv->bus); struct device *dev; int err = -ENODEV; dev = bus_find_device(bus, NULL, (void *)buf, driver_helper); if (dev && dev->driver == drv) { if (dev->parent) /* Needed for USB */ down(&dev->parent->sem); device_release_driver(dev); if (dev->parent) up(&dev->parent->sem); err = count; } put_device(dev); put_bus(bus); return err; } static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind); /* * Manually attach a device to a driver. * Note: the driver must want to bind to the device, * it is not possible to override the driver's id table. */ static ssize_t driver_bind(struct device_driver *drv, const char *buf, size_t count) { struct bus_type *bus = get_bus(drv->bus); struct device *dev; int err = -ENODEV; dev = bus_find_device(bus, NULL, (void *)buf, driver_helper); if (dev && dev->driver == NULL) { if (dev->parent) /* Needed for USB */ down(&dev->parent->sem); down(&dev->sem); err = driver_probe_device(drv, dev); up(&dev->sem); if (dev->parent) up(&dev->parent->sem); } put_device(dev); put_bus(bus); return err; } static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind); #endif static struct device * next_device(struct klist_iter * i) { struct klist_node * n = klist_next(i); return n ? container_of(n, struct device, knode_bus) : NULL; } /** * bus_for_each_dev - device iterator. * @bus: bus type. * @start: device to start iterating from. * @data: data for the callback. * @fn: function to be called for each device. * * Iterate over @bus's list of devices, and call @fn for each, * passing it @data. If @start is not NULL, we use that device to * begin iterating from. * * We check the return of @fn each time. If it returns anything * other than 0, we break out and return that value. * * NOTE: The device that returns a non-zero value is not retained * in any way, nor is its refcount incremented. If the caller needs * to retain this data, it should do, and increment the reference * count in the supplied callback. */ int bus_for_each_dev(struct bus_type * bus, struct device * start, void * data, int (*fn)(struct device *, void *)) { struct klist_iter i; struct device * dev; int error = 0; if (!bus) return -EINVAL; klist_iter_init_node(&bus->klist_devices, &i, (start ? &start->knode_bus : NULL)); while ((dev = next_device(&i)) && !error) error = fn(dev, data); klist_iter_exit(&i); return error; } /** * bus_find_device - device iterator for locating a particular device. * @bus: bus type * @start: Device to begin with * @data: Data to pass to match function * @match: Callback function to check device * * This is similar to the bus_for_each_dev() function above, but it * returns a reference to a device that is 'found' for later use, as * determined by the @match callback. * * The callback should return 0 if the device doesn't match and non-zero * if it does. If the callback returns non-zero, this function will * return to the caller and not iterate over any more devices. */ struct device * bus_find_device(struct bus_type *bus, struct device *start, void *data, int (*match)(struct device *, void *)) { struct klist_iter i; struct device *dev; if (!bus) return NULL; klist_iter_init_node(&bus->klist_devices, &i, (start ? &start->knode_bus : NULL)); while ((dev = next_device(&i))) if (match(dev, data) && get_device(dev)) break; klist_iter_exit(&i); return dev; } static struct device_driver * next_driver(struct klist_iter * i) { struct klist_node * n = klist_next(i); return n ? container_of(n, struct device_driver, knode_bus) : NULL; } /** * bus_for_each_drv - driver iterator * @bus: bus we're dealing with. * @start: driver to start iterating on. * @data: data to pass to the callback. * @fn: function to call for each driver. * * This is nearly identical to the device iterator above. * We iterate over each driver that belongs to @bus, and call * @fn for each. If @fn returns anything but 0, we break out * and return it. If @start is not NULL, we use it as the head * of the list. * * NOTE: we don't return the driver that returns a non-zero * value, nor do we leave the reference count incremented for that * driver. If the caller needs to know that info, it must set it * in the callback. It must also be sure to increment the refcount * so it doesn't disappear before returning to the caller. */ int bus_for_each_drv(struct bus_type * bus, struct device_driver * start, void * data, int (*fn)(struct device_driver *, void *)) { struct klist_iter i; struct device_driver * drv; int error = 0; if (!bus) return -EINVAL; klist_iter_init_node(&bus->klist_drivers, &i, start ? &start->knode_bus : NULL); while ((drv = next_driver(&i)) && !error) error = fn(drv, data); klist_iter_exit(&i); return error; } static int device_add_attrs(struct bus_type * bus, struct device * dev) { int error = 0; int i; if (bus->dev_attrs) { for (i = 0; attr_name(bus->dev_attrs[i]); i++) { error = device_create_file(dev,&bus->dev_attrs[i]); if (error) goto Err; } } Done: return error; Err: while (--i >= 0) device_remove_file(dev,&bus->dev_attrs[i]); goto Done; } static void device_remove_attrs(struct bus_type * bus, struct device * dev) { int i; if (bus->dev_attrs) { for (i = 0; attr_name(bus->dev_attrs[i]); i++) device_remove_file(dev,&bus->dev_attrs[i]); } } /** * bus_add_device - add device to bus * @dev: device being added * * - Add the device to its bus's list of devices. * - Try to attach to driver. * - Create link to device's physical location. */ int bus_add_device(struct device * dev) { struct bus_type * bus = get_bus(dev->bus); int error = 0; if (bus) { pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id); device_attach(dev); klist_add_tail(&dev->knode_bus, &bus->klist_devices); error = device_add_attrs(bus, dev); if (!error) { sysfs_create_link(&bus->devices.kobj, &dev->kobj, dev->bus_id); sysfs_create_link(&dev->kobj, &dev->bus->subsys.kset.kobj, "bus"); } } return error; } /** * bus_remove_device - remove device from bus * @dev: device to be removed * * - Remove symlink from bus's directory. * - Delete device from bus's list. * - Detach from its driver. * - Drop reference taken in bus_add_device(). */ void bus_remove_device(struct device * dev) { if (dev->bus) { sysfs_remove_link(&dev->kobj, "bus"); sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id); device_remove_attrs(dev->bus, dev); klist_remove(&dev->knode_bus); pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id); device_release_driver(dev); put_bus(dev->bus); } } static int driver_add_attrs(struct bus_type * bus, struct device_driver * drv) { int error = 0; int i; if (bus->drv_attrs) { for (i = 0; attr_name(bus->drv_attrs[i]); i++) { error = driver_create_file(drv, &bus->drv_attrs[i]); if (error) goto Err; } } Done: return error; Err: while (--i >= 0) driver_remove_file(drv, &bus->drv_attrs[i]); goto Done; } static void driver_remove_attrs(struct bus_type * bus, struct device_driver * drv) { int i; if (bus->drv_attrs) { for (i = 0; attr_name(bus->drv_attrs[i]); i++) driver_remove_file(drv, &bus->drv_attrs[i]); } } #ifdef CONFIG_HOTPLUG /* * Thanks to drivers making their tables __devinit, we can't allow manual * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled. */ static void add_bind_files(struct device_driver *drv) { driver_create_file(drv, &driver_attr_unbind); driver_create_file(drv, &driver_attr_bind); } static void remove_bind_files(struct device_driver *drv) { driver_remove_file(drv, &driver_attr_bind); driver_remove_file(drv, &driver_attr_unbind); } #else static inline void add_bind_files(struct device_driver *drv) {} static inline void remove_bind_files(struct device_driver *drv) {} #endif /** * bus_add_driver - Add a driver to the bus. * @drv: driver. * */ int bus_add_driver(struct device_driver * drv) { struct bus_type * bus = get_bus(drv->bus); int error = 0; if (bus) { pr_debug("bus %s: add driver %s\n", bus->name, drv->name); error = kobject_set_name(&drv->kobj, "%s", drv->name); if (error) { put_bus(bus); return error; } drv->kobj.kset = &bus->drivers; if ((error = kobject_register(&drv->kobj))) { put_bus(bus); return error; } driver_attach(drv); klist_add_tail(&drv->knode_bus, &bus->klist_drivers); module_add_driver(drv->owner, drv); driver_add_attrs(bus, drv); add_bind_files(drv); } return error; } /** * bus_remove_driver - delete driver from bus's knowledge. * @drv: driver. * * Detach the driver from the devices it controls, and remove * it from its bus's list of drivers. Finally, we drop the reference * to the bus we took in bus_add_driver(). */ void bus_remove_driver(struct device_driver * drv) { if (drv->bus) { remove_bind_files(drv); driver_remove_attrs(drv->bus, drv); klist_remove(&drv->knode_bus); pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name); driver_detach(drv); module_remove_driver(drv); kobject_unregister(&drv->kobj); put_bus(drv->bus); } } /* Helper for bus_rescan_devices's iter */ static int bus_rescan_devices_helper(struct device *dev, void *data) { if (!dev->driver) { if (dev->parent) /* Needed for USB */ down(&dev->parent->sem); device_attach(dev); if (dev->parent) up(&dev->parent->sem); } return 0; } /** * bus_rescan_devices - rescan devices on the bus for possible drivers * @bus: the bus to scan. * * This function will look for devices on the bus with no driver * attached and rescan it against existing drivers to see if it matches * any by calling device_attach() for the unbound devices. */ void bus_rescan_devices(struct bus_type * bus) { bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper); } /** * device_reprobe - remove driver for a device and probe for a new driver * @dev: the device to reprobe * * This function detaches the attached driver (if any) for the given * device and restarts the driver probing process. It is intended * to use if probing criteria changed during a devices lifetime and * driver attachment should change accordingly. */ void device_reprobe(struct device *dev) { if (dev->driver) { if (dev->parent) /* Needed for USB */ down(&dev->parent->sem); device_release_driver(dev); if (dev->parent) up(&dev->parent->sem); } bus_rescan_devices_helper(dev, NULL); } EXPORT_SYMBOL_GPL(device_reprobe); struct bus_type * get_bus(struct bus_type * bus) { return bus ? container_of(subsys_get(&bus->subsys), struct bus_type, subsys) : NULL; } void put_bus(struct bus_type * bus) { subsys_put(&bus->subsys); } /** * find_bus - locate bus by name. * @name: name of bus. * * Call kset_find_obj() to iterate over list of buses to * find a bus by name. Return bus if found. * * Note that kset_find_obj increments bus' reference count. */ struct bus_type * find_bus(char * name) { struct kobject * k = kset_find_obj(&bus_subsys.kset, name); return k ? to_bus(k) : NULL; } /** * bus_add_attrs - Add default attributes for this bus. * @bus: Bus that has just been registered. */ static int bus_add_attrs(struct bus_type * bus) { int error = 0; int i; if (bus->bus_attrs) { for (i = 0; attr_name(bus->bus_attrs[i]); i++) { if ((error = bus_create_file(bus,&bus->bus_attrs[i]))) goto Err; } } Done: return error; Err: while (--i >= 0) bus_remove_file(bus,&bus->bus_attrs[i]); goto Done; } static void bus_remove_attrs(struct bus_type * bus) { int i; if (bus->bus_attrs) { for (i = 0; attr_name(bus->bus_attrs[i]); i++) bus_remove_file(bus,&bus->bus_attrs[i]); } } static void klist_devices_get(struct klist_node *n) { struct device *dev = container_of(n, struct device, knode_bus); get_device(dev); } static void klist_devices_put(struct klist_node *n) { struct device *dev = container_of(n, struct device, knode_bus); put_device(dev); } static void klist_drivers_get(struct klist_node *n) { struct device_driver *drv = container_of(n, struct device_driver, knode_bus); get_driver(drv); } static void klist_drivers_put(struct klist_node *n) { struct device_driver *drv = container_of(n, struct device_driver, knode_bus); put_driver(drv); } /** * bus_register - register a bus with the system. * @bus: bus. * * Once we have that, we registered the bus with the kobject * infrastructure, then register the children subsystems it has: * the devices and drivers that belong to the bus. */ int bus_register(struct bus_type * bus) { int retval; retval = kobject_set_name(&bus->subsys.kset.kobj, "%s", bus->name); if (retval) goto out; subsys_set_kset(bus, bus_subsys); retval = subsystem_register(&bus->subsys); if (retval) goto out; kobject_set_name(&bus->devices.kobj, "devices"); bus->devices.subsys = &bus->subsys; retval = kset_register(&bus->devices); if (retval) goto bus_devices_fail; kobject_set_name(&bus->drivers.kobj, "drivers"); bus->drivers.subsys = &bus->subsys; bus->drivers.ktype = &ktype_driver; retval = kset_register(&bus->drivers); if (retval) goto bus_drivers_fail; klist_init(&bus->klist_devices, klist_devices_get, klist_devices_put); klist_init(&bus->klist_drivers, klist_drivers_get, klist_drivers_put); bus_add_attrs(bus); pr_debug("bus type '%s' registered\n", bus->name); return 0; bus_drivers_fail: kset_unregister(&bus->devices); bus_devices_fail: subsystem_unregister(&bus->subsys); out: return retval; } /** * bus_unregister - remove a bus from the system * @bus: bus. * * Unregister the child subsystems and the bus itself. * Finally, we call put_bus() to release the refcount */ void bus_unregister(struct bus_type * bus) { pr_debug("bus %s: unregistering\n", bus->name); bus_remove_attrs(bus); kset_unregister(&bus->drivers); kset_unregister(&bus->devices); subsystem_unregister(&bus->subsys); } int __init buses_init(void) { return subsystem_register(&bus_subsys); } EXPORT_SYMBOL_GPL(bus_for_each_dev); EXPORT_SYMBOL_GPL(bus_find_device); EXPORT_SYMBOL_GPL(bus_for_each_drv); EXPORT_SYMBOL_GPL(bus_add_device); EXPORT_SYMBOL_GPL(bus_remove_device); EXPORT_SYMBOL_GPL(bus_register); EXPORT_SYMBOL_GPL(bus_unregister); EXPORT_SYMBOL_GPL(bus_rescan_devices); EXPORT_SYMBOL_GPL(get_bus); EXPORT_SYMBOL_GPL(put_bus); EXPORT_SYMBOL_GPL(find_bus); EXPORT_SYMBOL_GPL(bus_create_file); EXPORT_SYMBOL_GPL(bus_remove_file);