diff options
Diffstat (limited to 'drivers/base/bus.c')
| -rw-r--r-- | drivers/base/bus.c | 1385 |
1 files changed, 1385 insertions, 0 deletions
diff --git a/drivers/base/bus.c b/drivers/base/bus.c new file mode 100644 index 0000000000..84a21084d6 --- /dev/null +++ b/drivers/base/bus.c @@ -0,0 +1,1385 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * bus.c - bus driver management + * + * Copyright (c) 2002-3 Patrick Mochel + * Copyright (c) 2002-3 Open Source Development Labs + * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de> + * Copyright (c) 2007 Novell Inc. + * Copyright (c) 2023 Greg Kroah-Hartman <gregkh@linuxfoundation.org> + */ + +#include <linux/async.h> +#include <linux/device/bus.h> +#include <linux/device.h> +#include <linux/module.h> +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/string.h> +#include <linux/mutex.h> +#include <linux/sysfs.h> +#include "base.h" +#include "power/power.h" + +/* /sys/devices/system */ +static struct kset *system_kset; + +/* /sys/bus */ +static struct kset *bus_kset; + +#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr) + +/* + * sysfs bindings for drivers + */ + +#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr) + +#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \ + struct driver_attribute driver_attr_##_name = \ + __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) + +static int __must_check bus_rescan_devices_helper(struct device *dev, + void *data); + +/** + * bus_to_subsys - Turn a struct bus_type into a struct subsys_private + * + * @bus: pointer to the struct bus_type to look up + * + * The driver core internals needs to work on the subsys_private structure, not + * the external struct bus_type pointer. This function walks the list of + * registered busses in the system and finds the matching one and returns the + * internal struct subsys_private that relates to that bus. + * + * Note, the reference count of the return value is INCREMENTED if it is not + * NULL. A call to subsys_put() must be done when finished with the pointer in + * order for it to be properly freed. + */ +static struct subsys_private *bus_to_subsys(const struct bus_type *bus) +{ + struct subsys_private *sp = NULL; + struct kobject *kobj; + + if (!bus || !bus_kset) + return NULL; + + spin_lock(&bus_kset->list_lock); + + if (list_empty(&bus_kset->list)) + goto done; + + list_for_each_entry(kobj, &bus_kset->list, entry) { + struct kset *kset = container_of(kobj, struct kset, kobj); + + sp = container_of_const(kset, struct subsys_private, subsys); + if (sp->bus == bus) + goto done; + } + sp = NULL; +done: + sp = subsys_get(sp); + spin_unlock(&bus_kset->list_lock); + return sp; +} + +static const struct bus_type *bus_get(const struct bus_type *bus) +{ + struct subsys_private *sp = bus_to_subsys(bus); + + if (sp) + return bus; + return NULL; +} + +static void bus_put(const struct bus_type *bus) +{ + struct subsys_private *sp = bus_to_subsys(bus); + + /* two puts are required as the call to bus_to_subsys incremented it again */ + subsys_put(sp); + subsys_put(sp); +} + +static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr, + char *buf) +{ + struct driver_attribute *drv_attr = to_drv_attr(attr); + struct driver_private *drv_priv = to_driver(kobj); + ssize_t ret = -EIO; + + if (drv_attr->show) + ret = drv_attr->show(drv_priv->driver, 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 driver_private *drv_priv = to_driver(kobj); + ssize_t ret = -EIO; + + if (drv_attr->store) + ret = drv_attr->store(drv_priv->driver, buf, count); + return ret; +} + +static const struct sysfs_ops driver_sysfs_ops = { + .show = drv_attr_show, + .store = drv_attr_store, +}; + +static void driver_release(struct kobject *kobj) +{ + struct driver_private *drv_priv = to_driver(kobj); + + pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__); + kfree(drv_priv); +} + +static const struct kobj_type driver_ktype = { + .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 subsys_private *subsys_priv = to_subsys_private(kobj); + ssize_t ret = 0; + + if (bus_attr->show) + ret = bus_attr->show(subsys_priv->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 subsys_private *subsys_priv = to_subsys_private(kobj); + ssize_t ret = 0; + + if (bus_attr->store) + ret = bus_attr->store(subsys_priv->bus, buf, count); + return ret; +} + +static const struct sysfs_ops bus_sysfs_ops = { + .show = bus_attr_show, + .store = bus_attr_store, +}; + +int bus_create_file(const struct bus_type *bus, struct bus_attribute *attr) +{ + struct subsys_private *sp = bus_to_subsys(bus); + int error; + + if (!sp) + return -EINVAL; + + error = sysfs_create_file(&sp->subsys.kobj, &attr->attr); + + subsys_put(sp); + return error; +} +EXPORT_SYMBOL_GPL(bus_create_file); + +void bus_remove_file(const struct bus_type *bus, struct bus_attribute *attr) +{ + struct subsys_private *sp = bus_to_subsys(bus); + + if (!sp) + return; + + sysfs_remove_file(&sp->subsys.kobj, &attr->attr); + subsys_put(sp); +} +EXPORT_SYMBOL_GPL(bus_remove_file); + +static void bus_release(struct kobject *kobj) +{ + struct subsys_private *priv = to_subsys_private(kobj); + + lockdep_unregister_key(&priv->lock_key); + kfree(priv); +} + +static const struct kobj_type bus_ktype = { + .sysfs_ops = &bus_sysfs_ops, + .release = bus_release, +}; + +static int bus_uevent_filter(const struct kobject *kobj) +{ + const struct kobj_type *ktype = get_ktype(kobj); + + if (ktype == &bus_ktype) + return 1; + return 0; +} + +static const struct kset_uevent_ops bus_uevent_ops = { + .filter = bus_uevent_filter, +}; + +/* Manually detach a device from its associated driver. */ +static ssize_t unbind_store(struct device_driver *drv, const char *buf, + size_t count) +{ + const struct bus_type *bus = bus_get(drv->bus); + struct device *dev; + int err = -ENODEV; + + dev = bus_find_device_by_name(bus, NULL, buf); + if (dev && dev->driver == drv) { + device_driver_detach(dev); + err = count; + } + put_device(dev); + bus_put(bus); + return err; +} +static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store); + +/* + * 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 bind_store(struct device_driver *drv, const char *buf, + size_t count) +{ + const struct bus_type *bus = bus_get(drv->bus); + struct device *dev; + int err = -ENODEV; + + dev = bus_find_device_by_name(bus, NULL, buf); + if (dev && driver_match_device(drv, dev)) { + err = device_driver_attach(drv, dev); + if (!err) { + /* success */ + err = count; + } + } + put_device(dev); + bus_put(bus); + return err; +} +static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store); + +static ssize_t drivers_autoprobe_show(const struct bus_type *bus, char *buf) +{ + struct subsys_private *sp = bus_to_subsys(bus); + int ret; + + if (!sp) + return -EINVAL; + + ret = sysfs_emit(buf, "%d\n", sp->drivers_autoprobe); + subsys_put(sp); + return ret; +} + +static ssize_t drivers_autoprobe_store(const struct bus_type *bus, + const char *buf, size_t count) +{ + struct subsys_private *sp = bus_to_subsys(bus); + + if (!sp) + return -EINVAL; + + if (buf[0] == '0') + sp->drivers_autoprobe = 0; + else + sp->drivers_autoprobe = 1; + + subsys_put(sp); + return count; +} + +static ssize_t drivers_probe_store(const struct bus_type *bus, + const char *buf, size_t count) +{ + struct device *dev; + int err = -EINVAL; + + dev = bus_find_device_by_name(bus, NULL, buf); + if (!dev) + return -ENODEV; + if (bus_rescan_devices_helper(dev, NULL) == 0) + err = count; + put_device(dev); + return err; +} + +static struct device *next_device(struct klist_iter *i) +{ + struct klist_node *n = klist_next(i); + struct device *dev = NULL; + struct device_private *dev_prv; + + if (n) { + dev_prv = to_device_private_bus(n); + dev = dev_prv->device; + } + return dev; +} + +/** + * 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 so, and increment the reference + * count in the supplied callback. + */ +int bus_for_each_dev(const struct bus_type *bus, struct device *start, + void *data, int (*fn)(struct device *, void *)) +{ + struct subsys_private *sp = bus_to_subsys(bus); + struct klist_iter i; + struct device *dev; + int error = 0; + + if (!sp) + return -EINVAL; + + klist_iter_init_node(&sp->klist_devices, &i, + (start ? &start->p->knode_bus : NULL)); + while (!error && (dev = next_device(&i))) + error = fn(dev, data); + klist_iter_exit(&i); + subsys_put(sp); + return error; +} +EXPORT_SYMBOL_GPL(bus_for_each_dev); + +/** + * 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(const struct bus_type *bus, + struct device *start, const void *data, + int (*match)(struct device *dev, const void *data)) +{ + struct subsys_private *sp = bus_to_subsys(bus); + struct klist_iter i; + struct device *dev; + + if (!sp) + return NULL; + + klist_iter_init_node(&sp->klist_devices, &i, + (start ? &start->p->knode_bus : NULL)); + while ((dev = next_device(&i))) + if (match(dev, data) && get_device(dev)) + break; + klist_iter_exit(&i); + subsys_put(sp); + return dev; +} +EXPORT_SYMBOL_GPL(bus_find_device); + +static struct device_driver *next_driver(struct klist_iter *i) +{ + struct klist_node *n = klist_next(i); + struct driver_private *drv_priv; + + if (n) { + drv_priv = container_of(n, struct driver_private, knode_bus); + return drv_priv->driver; + } + return 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(const struct bus_type *bus, struct device_driver *start, + void *data, int (*fn)(struct device_driver *, void *)) +{ + struct subsys_private *sp = bus_to_subsys(bus); + struct klist_iter i; + struct device_driver *drv; + int error = 0; + + if (!sp) + return -EINVAL; + + klist_iter_init_node(&sp->klist_drivers, &i, + start ? &start->p->knode_bus : NULL); + while ((drv = next_driver(&i)) && !error) + error = fn(drv, data); + klist_iter_exit(&i); + subsys_put(sp); + return error; +} +EXPORT_SYMBOL_GPL(bus_for_each_drv); + +/** + * bus_add_device - add device to bus + * @dev: device being added + * + * - Add device's bus attributes. + * - Create links to device's bus. + * - Add the device to its bus's list of devices. + */ +int bus_add_device(struct device *dev) +{ + struct subsys_private *sp = bus_to_subsys(dev->bus); + int error; + + if (!sp) { + /* + * This is a normal operation for many devices that do not + * have a bus assigned to them, just say that all went + * well. + */ + return 0; + } + + /* + * Reference in sp is now incremented and will be dropped when + * the device is removed from the bus + */ + + pr_debug("bus: '%s': add device %s\n", sp->bus->name, dev_name(dev)); + + error = device_add_groups(dev, sp->bus->dev_groups); + if (error) + goto out_put; + + error = sysfs_create_link(&sp->devices_kset->kobj, &dev->kobj, dev_name(dev)); + if (error) + goto out_groups; + + error = sysfs_create_link(&dev->kobj, &sp->subsys.kobj, "subsystem"); + if (error) + goto out_subsys; + + klist_add_tail(&dev->p->knode_bus, &sp->klist_devices); + return 0; + +out_subsys: + sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev)); +out_groups: + device_remove_groups(dev, sp->bus->dev_groups); +out_put: + subsys_put(sp); + return error; +} + +/** + * bus_probe_device - probe drivers for a new device + * @dev: device to probe + * + * - Automatically probe for a driver if the bus allows it. + */ +void bus_probe_device(struct device *dev) +{ + struct subsys_private *sp = bus_to_subsys(dev->bus); + struct subsys_interface *sif; + + if (!sp) + return; + + if (sp->drivers_autoprobe) + device_initial_probe(dev); + + mutex_lock(&sp->mutex); + list_for_each_entry(sif, &sp->interfaces, node) + if (sif->add_dev) + sif->add_dev(dev, sif); + mutex_unlock(&sp->mutex); + subsys_put(sp); +} + +/** + * bus_remove_device - remove device from bus + * @dev: device to be removed + * + * - Remove device from all interfaces. + * - Remove symlink from bus' 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) +{ + struct subsys_private *sp = bus_to_subsys(dev->bus); + struct subsys_interface *sif; + + if (!sp) + return; + + mutex_lock(&sp->mutex); + list_for_each_entry(sif, &sp->interfaces, node) + if (sif->remove_dev) + sif->remove_dev(dev, sif); + mutex_unlock(&sp->mutex); + + sysfs_remove_link(&dev->kobj, "subsystem"); + sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev)); + device_remove_groups(dev, dev->bus->dev_groups); + if (klist_node_attached(&dev->p->knode_bus)) + klist_del(&dev->p->knode_bus); + + pr_debug("bus: '%s': remove device %s\n", + dev->bus->name, dev_name(dev)); + device_release_driver(dev); + + /* + * Decrement the reference count twice, once for the bus_to_subsys() + * call in the start of this function, and the second one from the + * reference increment in bus_add_device() + */ + subsys_put(sp); + subsys_put(sp); +} + +static int __must_check add_bind_files(struct device_driver *drv) +{ + int ret; + + ret = driver_create_file(drv, &driver_attr_unbind); + if (ret == 0) { + ret = driver_create_file(drv, &driver_attr_bind); + if (ret) + driver_remove_file(drv, &driver_attr_unbind); + } + return ret; +} + +static void remove_bind_files(struct device_driver *drv) +{ + driver_remove_file(drv, &driver_attr_bind); + driver_remove_file(drv, &driver_attr_unbind); +} + +static BUS_ATTR_WO(drivers_probe); +static BUS_ATTR_RW(drivers_autoprobe); + +static int add_probe_files(const struct bus_type *bus) +{ + int retval; + + retval = bus_create_file(bus, &bus_attr_drivers_probe); + if (retval) + goto out; + + retval = bus_create_file(bus, &bus_attr_drivers_autoprobe); + if (retval) + bus_remove_file(bus, &bus_attr_drivers_probe); +out: + return retval; +} + +static void remove_probe_files(const struct bus_type *bus) +{ + bus_remove_file(bus, &bus_attr_drivers_autoprobe); + bus_remove_file(bus, &bus_attr_drivers_probe); +} + +static ssize_t uevent_store(struct device_driver *drv, const char *buf, + size_t count) +{ + int rc; + + rc = kobject_synth_uevent(&drv->p->kobj, buf, count); + return rc ? rc : count; +} +static DRIVER_ATTR_WO(uevent); + +/** + * bus_add_driver - Add a driver to the bus. + * @drv: driver. + */ +int bus_add_driver(struct device_driver *drv) +{ + struct subsys_private *sp = bus_to_subsys(drv->bus); + struct driver_private *priv; + int error = 0; + + if (!sp) + return -EINVAL; + + /* + * Reference in sp is now incremented and will be dropped when + * the driver is removed from the bus + */ + pr_debug("bus: '%s': add driver %s\n", sp->bus->name, drv->name); + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) { + error = -ENOMEM; + goto out_put_bus; + } + klist_init(&priv->klist_devices, NULL, NULL); + priv->driver = drv; + drv->p = priv; + priv->kobj.kset = sp->drivers_kset; + error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL, + "%s", drv->name); + if (error) + goto out_unregister; + + klist_add_tail(&priv->knode_bus, &sp->klist_drivers); + if (sp->drivers_autoprobe) { + error = driver_attach(drv); + if (error) + goto out_del_list; + } + module_add_driver(drv->owner, drv); + + error = driver_create_file(drv, &driver_attr_uevent); + if (error) { + printk(KERN_ERR "%s: uevent attr (%s) failed\n", + __func__, drv->name); + } + error = driver_add_groups(drv, sp->bus->drv_groups); + if (error) { + /* How the hell do we get out of this pickle? Give up */ + printk(KERN_ERR "%s: driver_add_groups(%s) failed\n", + __func__, drv->name); + } + + if (!drv->suppress_bind_attrs) { + error = add_bind_files(drv); + if (error) { + /* Ditto */ + printk(KERN_ERR "%s: add_bind_files(%s) failed\n", + __func__, drv->name); + } + } + + return 0; + +out_del_list: + klist_del(&priv->knode_bus); +out_unregister: + kobject_put(&priv->kobj); + /* drv->p is freed in driver_release() */ + drv->p = NULL; +out_put_bus: + subsys_put(sp); + 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) +{ + struct subsys_private *sp = bus_to_subsys(drv->bus); + + if (!sp) + return; + + pr_debug("bus: '%s': remove driver %s\n", sp->bus->name, drv->name); + + if (!drv->suppress_bind_attrs) + remove_bind_files(drv); + driver_remove_groups(drv, sp->bus->drv_groups); + driver_remove_file(drv, &driver_attr_uevent); + klist_remove(&drv->p->knode_bus); + driver_detach(drv); + module_remove_driver(drv); + kobject_put(&drv->p->kobj); + + /* + * Decrement the reference count twice, once for the bus_to_subsys() + * call in the start of this function, and the second one from the + * reference increment in bus_add_driver() + */ + subsys_put(sp); + subsys_put(sp); +} + +/* Helper for bus_rescan_devices's iter */ +static int __must_check bus_rescan_devices_helper(struct device *dev, + void *data) +{ + int ret = 0; + + if (!dev->driver) { + if (dev->parent && dev->bus->need_parent_lock) + device_lock(dev->parent); + ret = device_attach(dev); + if (dev->parent && dev->bus->need_parent_lock) + device_unlock(dev->parent); + } + return ret < 0 ? ret : 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. + */ +int bus_rescan_devices(const struct bus_type *bus) +{ + return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper); +} +EXPORT_SYMBOL_GPL(bus_rescan_devices); + +/** + * 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. + */ +int device_reprobe(struct device *dev) +{ + if (dev->driver) + device_driver_detach(dev); + return bus_rescan_devices_helper(dev, NULL); +} +EXPORT_SYMBOL_GPL(device_reprobe); + +static void klist_devices_get(struct klist_node *n) +{ + struct device_private *dev_prv = to_device_private_bus(n); + struct device *dev = dev_prv->device; + + get_device(dev); +} + +static void klist_devices_put(struct klist_node *n) +{ + struct device_private *dev_prv = to_device_private_bus(n); + struct device *dev = dev_prv->device; + + put_device(dev); +} + +static ssize_t bus_uevent_store(const struct bus_type *bus, + const char *buf, size_t count) +{ + struct subsys_private *sp = bus_to_subsys(bus); + int ret; + + if (!sp) + return -EINVAL; + + ret = kobject_synth_uevent(&sp->subsys.kobj, buf, count); + subsys_put(sp); + + if (ret) + return ret; + return count; +} +/* + * "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO() + * here, but can not use it as earlier in the file we have + * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store + * function name. + */ +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) +{ + int retval; + struct subsys_private *priv; + struct kobject *bus_kobj; + struct lock_class_key *key; + + priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->bus = bus; + + BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier); + + bus_kobj = &priv->subsys.kobj; + retval = kobject_set_name(bus_kobj, "%s", bus->name); + if (retval) + goto out; + + bus_kobj->kset = bus_kset; + bus_kobj->ktype = &bus_ktype; + priv->drivers_autoprobe = 1; + + retval = kset_register(&priv->subsys); + if (retval) + goto out; + + retval = bus_create_file(bus, &bus_attr_uevent); + if (retval) + goto bus_uevent_fail; + + priv->devices_kset = kset_create_and_add("devices", NULL, bus_kobj); + if (!priv->devices_kset) { + retval = -ENOMEM; + 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; + } + + INIT_LIST_HEAD(&priv->interfaces); + key = &priv->lock_key; + lockdep_register_key(key); + __mutex_init(&priv->mutex, "subsys mutex", key); + 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; + + retval = sysfs_create_groups(bus_kobj, bus->bus_groups); + if (retval) + goto bus_groups_fail; + + pr_debug("bus: '%s': registered\n", bus->name); + return 0; + +bus_groups_fail: + remove_probe_files(bus); +bus_probe_files_fail: + kset_unregister(priv->drivers_kset); +bus_drivers_fail: + kset_unregister(priv->devices_kset); +bus_devices_fail: + bus_remove_file(bus, &bus_attr_uevent); +bus_uevent_fail: + kset_unregister(&priv->subsys); +out: + kfree(priv); + return retval; +} +EXPORT_SYMBOL_GPL(bus_register); + +/** + * bus_unregister - remove a bus from the system + * @bus: bus. + * + * Unregister the child subsystems and the bus itself. + * Finally, we call bus_put() to release the refcount + */ +void bus_unregister(const struct bus_type *bus) +{ + struct subsys_private *sp = bus_to_subsys(bus); + struct kobject *bus_kobj; + + if (!sp) + return; + + pr_debug("bus: '%s': unregistering\n", bus->name); + if (sp->dev_root) + device_unregister(sp->dev_root); + + bus_kobj = &sp->subsys.kobj; + sysfs_remove_groups(bus_kobj, bus->bus_groups); + remove_probe_files(bus); + bus_remove_file(bus, &bus_attr_uevent); + + kset_unregister(sp->drivers_kset); + kset_unregister(sp->devices_kset); + kset_unregister(&sp->subsys); + subsys_put(sp); +} +EXPORT_SYMBOL_GPL(bus_unregister); + +int bus_register_notifier(const struct bus_type *bus, struct notifier_block *nb) +{ + struct subsys_private *sp = bus_to_subsys(bus); + int retval; + + if (!sp) + return -EINVAL; + + retval = blocking_notifier_chain_register(&sp->bus_notifier, nb); + subsys_put(sp); + return retval; +} +EXPORT_SYMBOL_GPL(bus_register_notifier); + +int bus_unregister_notifier(const struct bus_type *bus, struct notifier_block *nb) +{ + struct subsys_private *sp = bus_to_subsys(bus); + int retval; + + if (!sp) + return -EINVAL; + retval = blocking_notifier_chain_unregister(&sp->bus_notifier, nb); + subsys_put(sp); + return retval; +} +EXPORT_SYMBOL_GPL(bus_unregister_notifier); + +void bus_notify(struct device *dev, enum bus_notifier_event value) +{ + struct subsys_private *sp = bus_to_subsys(dev->bus); + + if (!sp) + return; + + blocking_notifier_call_chain(&sp->bus_notifier, value, dev); + subsys_put(sp); +} + +struct kset *bus_get_kset(const struct bus_type *bus) +{ + struct subsys_private *sp = bus_to_subsys(bus); + struct kset *kset; + + if (!sp) + return NULL; + + kset = &sp->subsys; + subsys_put(sp); + + return kset; +} +EXPORT_SYMBOL_GPL(bus_get_kset); + +/* + * Yes, this forcibly breaks the klist abstraction temporarily. It + * just wants to sort the klist, not change reference counts and + * take/drop locks rapidly in the process. It does all this while + * holding the lock for the list, so objects can't otherwise be + * added/removed while we're swizzling. + */ +static void device_insertion_sort_klist(struct device *a, struct list_head *list, + int (*compare)(const struct device *a, + const struct device *b)) +{ + struct klist_node *n; + struct device_private *dev_prv; + struct device *b; + + list_for_each_entry(n, list, n_node) { + dev_prv = to_device_private_bus(n); + b = dev_prv->device; + if (compare(a, b) <= 0) { + list_move_tail(&a->p->knode_bus.n_node, + &b->p->knode_bus.n_node); + return; + } + } + list_move_tail(&a->p->knode_bus.n_node, list); +} + +void bus_sort_breadthfirst(struct bus_type *bus, + int (*compare)(const struct device *a, + const struct device *b)) +{ + struct subsys_private *sp = bus_to_subsys(bus); + LIST_HEAD(sorted_devices); + struct klist_node *n, *tmp; + struct device_private *dev_prv; + struct device *dev; + struct klist *device_klist; + + if (!sp) + return; + device_klist = &sp->klist_devices; + + spin_lock(&device_klist->k_lock); + list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) { + dev_prv = to_device_private_bus(n); + dev = dev_prv->device; + device_insertion_sort_klist(dev, &sorted_devices, compare); + } + list_splice(&sorted_devices, &device_klist->k_list); + spin_unlock(&device_klist->k_lock); + subsys_put(sp); +} +EXPORT_SYMBOL_GPL(bus_sort_breadthfirst); + +struct subsys_dev_iter { + struct klist_iter ki; + const struct device_type *type; +}; + +/** + * subsys_dev_iter_init - initialize subsys device iterator + * @iter: subsys iterator to initialize + * @sp: the subsys private (i.e. bus) we wanna iterate over + * @start: the device to start iterating from, if any + * @type: device_type of the devices to iterate over, NULL for all + * + * Initialize subsys iterator @iter such that it iterates over devices + * of @subsys. If @start is set, the list iteration will start there, + * otherwise if it is NULL, the iteration starts at the beginning of + * the list. + */ +static void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct subsys_private *sp, + struct device *start, const struct device_type *type) +{ + struct klist_node *start_knode = NULL; + + if (start) + start_knode = &start->p->knode_bus; + klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode); + iter->type = type; +} + +/** + * subsys_dev_iter_next - iterate to the next device + * @iter: subsys iterator to proceed + * + * Proceed @iter to the next device and return it. Returns NULL if + * iteration is complete. + * + * The returned device is referenced and won't be released till + * iterator is proceed to the next device or exited. The caller is + * free to do whatever it wants to do with the device including + * calling back into subsys code. + */ +static struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter) +{ + struct klist_node *knode; + struct device *dev; + + for (;;) { + knode = klist_next(&iter->ki); + if (!knode) + return NULL; + dev = to_device_private_bus(knode)->device; + if (!iter->type || iter->type == dev->type) + return dev; + } +} + +/** + * subsys_dev_iter_exit - finish iteration + * @iter: subsys iterator to finish + * + * Finish an iteration. Always call this function after iteration is + * complete whether the iteration ran till the end or not. + */ +static void subsys_dev_iter_exit(struct subsys_dev_iter *iter) +{ + klist_iter_exit(&iter->ki); +} + +int subsys_interface_register(struct subsys_interface *sif) +{ + struct subsys_private *sp; + struct subsys_dev_iter iter; + struct device *dev; + + if (!sif || !sif->subsys) + return -ENODEV; + + sp = bus_to_subsys(sif->subsys); + if (!sp) + return -EINVAL; + + /* + * Reference in sp is now incremented and will be dropped when + * the interface is removed from the bus + */ + + mutex_lock(&sp->mutex); + list_add_tail(&sif->node, &sp->interfaces); + if (sif->add_dev) { + subsys_dev_iter_init(&iter, sp, NULL, NULL); + while ((dev = subsys_dev_iter_next(&iter))) + sif->add_dev(dev, sif); + subsys_dev_iter_exit(&iter); + } + mutex_unlock(&sp->mutex); + + return 0; +} +EXPORT_SYMBOL_GPL(subsys_interface_register); + +void subsys_interface_unregister(struct subsys_interface *sif) +{ + struct subsys_private *sp; + struct subsys_dev_iter iter; + struct device *dev; + + if (!sif || !sif->subsys) + return; + + sp = bus_to_subsys(sif->subsys); + if (!sp) + return; + + mutex_lock(&sp->mutex); + list_del_init(&sif->node); + if (sif->remove_dev) { + subsys_dev_iter_init(&iter, sp, NULL, NULL); + while ((dev = subsys_dev_iter_next(&iter))) + sif->remove_dev(dev, sif); + subsys_dev_iter_exit(&iter); + } + mutex_unlock(&sp->mutex); + + /* + * Decrement the reference count twice, once for the bus_to_subsys() + * call in the start of this function, and the second one from the + * reference increment in subsys_interface_register() + */ + subsys_put(sp); + subsys_put(sp); +} +EXPORT_SYMBOL_GPL(subsys_interface_unregister); + +static void system_root_device_release(struct device *dev) +{ + kfree(dev); +} + +static int subsys_register(struct bus_type *subsys, + const struct attribute_group **groups, + struct kobject *parent_of_root) +{ + struct subsys_private *sp; + struct device *dev; + int err; + + err = bus_register(subsys); + if (err < 0) + return err; + + sp = bus_to_subsys(subsys); + if (!sp) { + err = -EINVAL; + goto err_sp; + } + + dev = kzalloc(sizeof(struct device), GFP_KERNEL); + if (!dev) { + err = -ENOMEM; + goto err_dev; + } + + err = dev_set_name(dev, "%s", subsys->name); + if (err < 0) + goto err_name; + + dev->kobj.parent = parent_of_root; + dev->groups = groups; + dev->release = system_root_device_release; + + err = device_register(dev); + if (err < 0) + goto err_dev_reg; + + sp->dev_root = dev; + subsys_put(sp); + return 0; + +err_dev_reg: + put_device(dev); + dev = NULL; +err_name: + kfree(dev); +err_dev: + subsys_put(sp); +err_sp: + bus_unregister(subsys); + return err; +} + +/** + * subsys_system_register - register a subsystem at /sys/devices/system/ + * @subsys: system subsystem + * @groups: default attributes for the root device + * + * All 'system' subsystems have a /sys/devices/system/<name> root device + * with the name of the subsystem. The root device can carry subsystem- + * wide attributes. All registered devices are below this single root + * device and are named after the subsystem with a simple enumeration + * number appended. The registered devices are not explicitly named; + * only 'id' in the device needs to be set. + * + * Do not use this interface for anything new, it exists for compatibility + * with bad ideas only. New subsystems should use plain subsystems; and + * add the subsystem-wide attributes should be added to the subsystem + * directory itself and not some create fake root-device placed in + * /sys/devices/system/<name>. + */ +int subsys_system_register(struct bus_type *subsys, + const struct attribute_group **groups) +{ + return subsys_register(subsys, groups, &system_kset->kobj); +} +EXPORT_SYMBOL_GPL(subsys_system_register); + +/** + * subsys_virtual_register - register a subsystem at /sys/devices/virtual/ + * @subsys: virtual subsystem + * @groups: default attributes for the root device + * + * All 'virtual' subsystems have a /sys/devices/system/<name> root device + * with the name of the subystem. The root device can carry subsystem-wide + * attributes. All registered devices are below this single root device. + * There's no restriction on device naming. This is for kernel software + * constructs which need sysfs interface. + */ +int subsys_virtual_register(struct bus_type *subsys, + const struct attribute_group **groups) +{ + struct kobject *virtual_dir; + + virtual_dir = virtual_device_parent(NULL); + if (!virtual_dir) + return -ENOMEM; + + return subsys_register(subsys, groups, virtual_dir); +} +EXPORT_SYMBOL_GPL(subsys_virtual_register); + +/** + * driver_find - locate driver on a bus by its name. + * @name: name of the driver. + * @bus: bus to scan for the driver. + * + * Call kset_find_obj() to iterate over list of drivers on + * a bus to find driver by name. Return driver if found. + * + * This routine provides no locking to prevent the driver it returns + * from being unregistered or unloaded while the caller is using it. + * The caller is responsible for preventing this. + */ +struct device_driver *driver_find(const char *name, const struct bus_type *bus) +{ + struct subsys_private *sp = bus_to_subsys(bus); + struct kobject *k; + struct driver_private *priv; + + if (!sp) + return NULL; + + k = kset_find_obj(sp->drivers_kset, name); + subsys_put(sp); + if (!k) + return NULL; + + priv = to_driver(k); + + /* Drop reference added by kset_find_obj() */ + kobject_put(k); + return priv->driver; +} +EXPORT_SYMBOL_GPL(driver_find); + +/* + * Warning, the value could go to "removed" instantly after calling this function, so be very + * careful when calling it... + */ +bool bus_is_registered(const struct bus_type *bus) +{ + struct subsys_private *sp = bus_to_subsys(bus); + bool is_initialized = false; + + if (sp) { + is_initialized = true; + subsys_put(sp); + } + return is_initialized; +} + +/** + * bus_get_dev_root - return a pointer to the "device root" of a bus + * @bus: bus to return the device root of. + * + * If a bus has a "device root" structure, return it, WITH THE REFERENCE + * COUNT INCREMENTED. + * + * Note, when finished with the device, a call to put_device() is required. + * + * If the device root is not present (or bus is not a valid pointer), NULL + * will be returned. + */ +struct device *bus_get_dev_root(const struct bus_type *bus) +{ + struct subsys_private *sp = bus_to_subsys(bus); + struct device *dev_root; + + if (!sp) + return NULL; + + dev_root = get_device(sp->dev_root); + subsys_put(sp); + return dev_root; +} +EXPORT_SYMBOL_GPL(bus_get_dev_root); + +int __init buses_init(void) +{ + bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL); + if (!bus_kset) + return -ENOMEM; + + system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj); + if (!system_kset) + return -ENOMEM; + + return 0; +} |