// 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 <[email protected]>
* Copyright (c) 2007 Novell Inc.
* Copyright (c) 2023 Greg Kroah-Hartman <[email protected]>
*/
#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);
/* return -EIO for reading a bus attribute without show() */
ssize_t ret = -EIO;
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);
/* return -EIO for writing a bus attribute without store() */
ssize_t ret = -EIO;
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,
device_match_t match)
{
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;
}
error = module_add_driver(drv->owner, drv);
if (error) {
printk(KERN_ERR "%s: failed to create module links for %s\n",
__func__, drv->name);
goto out_detach;
}
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_detach:
driver_detach(drv);
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);
/* Above kset_unregister() will kfree @priv */
priv = NULL;
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(const 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(const 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(const 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(const struct bus_type *subsys,
const struct attribute_group **groups)
{
struct kobject *virtual_dir;
virtual_dir = virtual_device_parent();
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) {
/* Do error handling here as devices_init() do */
kset_unregister(bus_kset);
bus_kset = NULL;
pr_err("%s: failed to create and add kset 'bus'\n", __func__);
return -ENOMEM;
}
return 0;
}
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