/*
* 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_dev(node) container_of(node, struct device, bus_list)
#define to_drv(node) container_of(node, struct device_driver, kobj.entry)
#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 = 0;
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 = 0;
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);
static int __bus_for_each_dev(struct bus_type *bus, struct device *start,
void *data, int (*fn)(struct device *, void *))
{
struct list_head *head;
struct device *dev;
int error = 0;
if (!(bus = get_bus(bus)))
return -EINVAL;
head = &bus->devices.list;
dev = list_prepare_entry(start, head, bus_list);
list_for_each_entry_continue(dev, head, bus_list) {
get_device(dev);
error = fn(dev, data);
put_device(dev);
if (error)
break;
}
put_bus(bus);
return error;
}
static int __bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
void * data, int (*fn)(struct device_driver *, void *))
{
struct list_head *head;
struct device_driver *drv;
int error = 0;
if (!(bus = get_bus(bus)))
return -EINVAL;
head = &bus->drivers.list;
drv = list_prepare_entry(start, head, kobj.entry);
list_for_each_entry_continue(drv, head, kobj.entry) {
get_driver(drv);
error = fn(drv, data);
put_driver(drv);
if (error)
break;
}
put_bus(bus);
return error;
}
/**
* 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 *))
{
int ret;
down_read(&bus->subsys.rwsem);
ret = __bus_for_each_dev(bus, start, data, fn);
up_read(&bus->subsys.rwsem);
return ret;
}
/**
* 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 *))
{
int ret;
down_read(&bus->subsys.rwsem);
ret = __bus_for_each_drv(bus, start, data, fn);
up_read(&bus->subsys.rwsem);
return ret;
}
/**
* device_bind_driver - bind a driver to one device.
* @dev: device.
*
* Allow manual attachment of a driver to a device.
* Caller must have already set @dev->driver.
*
* Note that this does not modify the bus reference count
* nor take the bus's rwsem. Please verify those are accounted
* for before calling this. (It is ok to call with no other effort
* from a driver's probe() method.)
*/
void device_bind_driver(struct device * dev)
{
pr_debug("bound device '%s' to driver '%s'\n",
dev->bus_id, dev->driver->name);
list_add_tail(&dev->driver_list, &dev->driver->devices);
sysfs_create_link(&dev->driver->kobj, &dev->kobj,
kobject_name(&dev->kobj));
sysfs_create_link(&dev->kobj, &dev->driver->kobj, "driver");
}
/**
* driver_probe_device - attempt to bind device & driver.
* @drv: driver.
* @dev: device.
*
* First, we call the bus's match function, if one present, which
* should compare the device IDs the driver supports with the
* device IDs of the device. Note we don't do this ourselves
* because we don't know the format of the ID structures, nor what
* is to be considered a match and what is not.
*
* If we find a match, we call @drv->probe(@dev) if it exists, and
* call device_bind_driver() above.
*/
int driver_probe_device(struct device_driver * drv, struct device * dev)
{
if (drv->bus->match && !drv->bus->match(dev, drv))
return -ENODEV;
dev->driver = drv;
if (drv->probe) {
int error = drv->probe(dev);
if (error) {
dev->driver = NULL;
return error;
}
}
device_bind_driver(dev);
return 0;
}
/**
* device_attach - try to attach device to a driver.
* @dev: device.
*
* Walk the list of drivers that the bus has and call
* driver_probe_device() for each pair. If a compatible
* pair is found, break out and return.
*/
int device_attach(struct device * dev)
{
struct bus_type * bus = dev->bus;
struct list_head * entry;
int error;
if (dev->driver) {
device_bind_driver(dev);
return 1;
}
if (bus->match) {
list_for_each(entry, &bus->drivers.list) {
struct device_driver * drv = to_drv(entry);
error = driver_probe_device(drv, dev);
if (!error)
/* success, driver matched */
return 1;
if (error != -ENODEV && error != -ENXIO)
/* driver matched but the probe failed */
printk(KERN_WARNING
"%s: probe of %s failed with error %d\n",
drv->name, dev->bus_id, error);
}
}
return 0;
}
/**
* driver_attach - try to bind driver to devices.
* @drv: driver.
*
* Walk the list of devices that the bus has on it and try to
* match the driver with each one. If driver_probe_device()
* returns 0 and the @dev->driver is set, we've found a
* compatible pair.
*
* Note that we ignore the -ENODEV error from driver_probe_device(),
* since it's perfectly valid for a driver not to bind to any devices.
*/
void driver_attach(struct device_driver * drv)
{
struct bus_type * bus = drv->bus;
struct list_head * entry;
int error;
if (!bus->match)
return;
list_for_each(entry, &bus->devices.list) {
struct device * dev = container_of(entry, struct device, bus_list);
if (!dev->driver) {
error = driver_probe_device(drv, dev);
if (error && (error != -ENODEV))
/* driver matched but the probe failed */
printk(KERN_WARNING
"%s: probe of %s failed with error %d\n",
drv->name, dev->bus_id, error);
}
}
}
/**
* device_release_driver - manually detach device from driver.
* @dev: device.
*
* Manually detach device from driver.
* Note that this is called without incrementing the bus
* reference count nor taking the bus's rwsem. Be sure that
* those are accounted for before calling this function.
*/
void device_release_driver(struct device * dev)
{
struct device_driver * drv = dev->driver;
if (drv) {
sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
sysfs_remove_link(&dev->kobj, "driver");
list_del_init(&dev->driver_list);
if (drv->remove)
drv->remove(dev);
dev->driver = NULL;
}
}
/**
* driver_detach - detach driver from all devices it controls.
* @drv: driver.
*/
static void driver_detach(struct device_driver * drv)
{
while (!list_empty(&drv->devices)) {
struct device * dev = container_of(drv->devices.next, struct device, driver_list);
device_release_driver(dev);
}
}
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) {
down_write(&dev->bus->subsys.rwsem);
pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id);
list_add_tail(&dev->bus_list, &dev->bus->devices.list);
device_attach(dev);
up_write(&dev->bus->subsys.rwsem);
device_add_attrs(bus, dev);
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);
down_write(&dev->bus->subsys.rwsem);
pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
device_release_driver(dev);
list_del_init(&dev->bus_list);
up_write(&dev->bus->subsys.rwsem);
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]);
}
}
/**
* 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;
}
down_write(&bus->subsys.rwsem);
driver_attach(drv);
up_write(&bus->subsys.rwsem);
module_add_driver(drv->owner, drv);
driver_add_attrs(bus, 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) {
driver_remove_attrs(drv->bus, drv);
down_write(&drv->bus->subsys.rwsem);
pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name);
driver_detach(drv);
up_write(&drv->bus->subsys.rwsem);
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)
{
int *count = data;
if (!dev->driver && device_attach(dev))
(*count)++;
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. Calls device_attach(). Returns the number of devices
* that were sucessfully bound to a driver.
*/
int bus_rescan_devices(struct bus_type * bus)
{
int count = 0;
down_write(&bus->subsys.rwsem);
__bus_for_each_dev(bus, NULL, &count, bus_rescan_devices_helper);
up_write(&bus->subsys.rwsem);
return count;
}
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]);
}
}
/**
* 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;
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_for_each_drv);
EXPORT_SYMBOL_GPL(driver_probe_device);
EXPORT_SYMBOL_GPL(device_bind_driver);
EXPORT_SYMBOL_GPL(device_release_driver);
EXPORT_SYMBOL_GPL(device_attach);
EXPORT_SYMBOL_GPL(driver_attach);
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);
