// SPDX-License-Identifier: GPL-2.0
/*
* driver.c - centralized device 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.
*/
#include <linux/device/driver.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include "base.h"
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_driver(n);
dev = dev_prv->device;
}
return dev;
}
/**
* driver_set_override() - Helper to set or clear driver override.
* @dev: Device to change
* @override: Address of string to change (e.g. &device->driver_override);
* The contents will be freed and hold newly allocated override.
* @s: NUL-terminated string, new driver name to force a match, pass empty
* string to clear it ("" or "\n", where the latter is only for sysfs
* interface).
* @len: length of @s
*
* Helper to set or clear driver override in a device, intended for the cases
* when the driver_override field is allocated by driver/bus code.
*
* Returns: 0 on success or a negative error code on failure.
*/
int driver_set_override(struct device *dev, const char **override,
const char *s, size_t len)
{
const char *new, *old;
char *cp;
if (!override || !s)
return -EINVAL;
/*
* The stored value will be used in sysfs show callback (sysfs_emit()),
* which has a length limit of PAGE_SIZE and adds a trailing newline.
* Thus we can store one character less to avoid truncation during sysfs
* show.
*/
if (len >= (PAGE_SIZE - 1))
return -EINVAL;
/*
* Compute the real length of the string in case userspace sends us a
* bunch of \0 characters like python likes to do.
*/
len = strlen(s);
if (!len) {
/* Empty string passed - clear override */
device_lock(dev);
old = *override;
*override = NULL;
device_unlock(dev);
kfree(old);
return 0;
}
cp = strnchr(s, len, '\n');
if (cp)
len = cp - s;
new = kstrndup(s, len, GFP_KERNEL);
if (!new)
return -ENOMEM;
device_lock(dev);
old = *override;
if (cp != s) {
*override = new;
} else {
/* "\n" passed - clear override */
kfree(new);
*override = NULL;
}
device_unlock(dev);
kfree(old);
return 0;
}
EXPORT_SYMBOL_GPL(driver_set_override);
/**
* driver_for_each_device - Iterator for devices bound to a driver.
* @drv: Driver we're iterating.
* @start: Device to begin with
* @data: Data to pass to the callback.
* @fn: Function to call for each device.
*
* Iterate over the @drv's list of devices calling @fn for each one.
*/
int driver_for_each_device(struct device_driver *drv, struct device *start,
void *data, int (*fn)(struct device *, void *))
{
struct klist_iter i;
struct device *dev;
int error = 0;
if (!drv)
return -EINVAL;
klist_iter_init_node(&drv->p->klist_devices, &i,
start ? &start->p->knode_driver : NULL);
while (!error && (dev = next_device(&i)))
error = fn(dev, data);
klist_iter_exit(&i);
return error;
}
EXPORT_SYMBOL_GPL(driver_for_each_device);
/**
* driver_find_device - device iterator for locating a particular device.
* @drv: The device's driver
* @start: Device to begin with
* @data: Data to pass to match function
* @match: Callback function to check device
*
* This is similar to the driver_for_each_device() 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 *driver_find_device(const struct device_driver *drv,
struct device *start, const void *data,
device_match_t match)
{
struct klist_iter i;
struct device *dev;
if (!drv || !drv->p)
return NULL;
klist_iter_init_node(&drv->p->klist_devices, &i,
(start ? &start->p->knode_driver : NULL));
while ((dev = next_device(&i)))
if (match(dev, data) && get_device(dev))
break;
klist_iter_exit(&i);
return dev;
}
EXPORT_SYMBOL_GPL(driver_find_device);
/**
* driver_create_file - create sysfs file for driver.
* @drv: driver.
* @attr: driver attribute descriptor.
*/
int driver_create_file(const struct device_driver *drv,
const struct driver_attribute *attr)
{
int error;
if (drv)
error = sysfs_create_file(&drv->p->kobj, &attr->attr);
else
error = -EINVAL;
return error;
}
EXPORT_SYMBOL_GPL(driver_create_file);
/**
* driver_remove_file - remove sysfs file for driver.
* @drv: driver.
* @attr: driver attribute descriptor.
*/
void driver_remove_file(const struct device_driver *drv,
const struct driver_attribute *attr)
{
if (drv)
sysfs_remove_file(&drv->p->kobj, &attr->attr);
}
EXPORT_SYMBOL_GPL(driver_remove_file);
int driver_add_groups(const struct device_driver *drv,
const struct attribute_group **groups)
{
return sysfs_create_groups(&drv->p->kobj, groups);
}
void driver_remove_groups(const struct device_driver *drv,
const struct attribute_group **groups)
{
sysfs_remove_groups(&drv->p->kobj, groups);
}
/**
* driver_register - register driver with bus
* @drv: driver to register
*
* We pass off most of the work to the bus_add_driver() call,
* since most of the things we have to do deal with the bus
* structures.
*/
int driver_register(struct device_driver *drv)
{
int ret;
struct device_driver *other;
if (!bus_is_registered(drv->bus)) {
pr_err("Driver '%s' was unable to register with bus_type '%s' because the bus was not initialized.\n",
drv->name, drv->bus->name);
return -EINVAL;
}
if ((drv->bus->probe && drv->probe) ||
(drv->bus->remove && drv->remove) ||
(drv->bus->shutdown && drv->shutdown))
pr_warn("Driver '%s' needs updating - please use "
"bus_type methods\n", drv->name);
other = driver_find(drv->name, drv->bus);
if (other) {
pr_err("Error: Driver '%s' is already registered, "
"aborting...\n", drv->name);
return -EBUSY;
}
ret = bus_add_driver(drv);
if (ret)
return ret;
ret = driver_add_groups(drv, drv->groups);
if (ret) {
bus_remove_driver(drv);
return ret;
}
kobject_uevent(&drv->p->kobj, KOBJ_ADD);
deferred_probe_extend_timeout();
return ret;
}
EXPORT_SYMBOL_GPL(driver_register);
/**
* driver_unregister - remove driver from system.
* @drv: driver.
*
* Again, we pass off most of the work to the bus-level call.
*/
void driver_unregister(struct device_driver *drv)
{
if (!drv || !drv->p) {
WARN(1, "Unexpected driver unregister!\n");
return;
}
driver_remove_groups(drv, drv->groups);
bus_remove_driver(drv);
}
EXPORT_SYMBOL_GPL(driver_unregister);
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